YGIE 
 
 ■M fl Wjug iMir miMMMaaii HiiLUMJ ww uM WlW 
 
 HRtllMtS&FfcffMflf 
 
 N OTTER and FIRTH 
 
 
I »_>i-'fc.<^-' 
 
 -:¥. 
 
 
 PUBLIC 
 HEALTH 
 
 ART 
 

HYGIENE 
 
BY THE SAME AUTHORS 
 
 PRACTICAL DOMESTIC HYGIENE 
 With 84 Illustrations 
 
 Crown Sz'<?. 
 
 LONGMANS, GREEN AND CO, 
 
 LONDON, NEW YORK, BOMBAY, CALCUTTA, AND MADRAS 
 
H YGIEN 
 
 BY 
 
 J. LANE NOTTER 
 
 AND 
 
 R. H. FIRTH 
 
 WITH ILLUSTRATIONS 
 
 NINTH EDITION 
 
 LONGMANS, GREEN AND CO. 
 
 39 PATERNOSTER ROW, LONDON 
 
 FOURTH AVENUE AND 30th STREET, NEW YORK 
 BOMBAY, CALCUTTA, AND MADRAS 
 
 1921 
 
 All rights reserved 
 

 
 hmxw public* 
 
 HEALTH 
 LIBRARY 
 
PREFACE TO THE NINTH EDITION 
 
 In the preparation of this issue we have made no changes in 
 the general plan of the work, but have revised or rewritten all 
 sections where necessary to bring each up to date. Considerable 
 changes have been made in the sections dealing with the theory 
 of dietaries, the treatment of sewage, the infectious diseases and 
 sanitary law. A short section on the sanitation of camps has 
 been added to Chapter V., and a new chapter introduced dealing 
 with Child Welfare and School Hygiene. Owing to some recent 
 legislation, the chapter on sanitary law has been amplified and 
 placed abreast of the times. 
 
 In its new form, we hope that this manual will be found to 
 have retained its value as a plain and reliable guide to the pre- 
 vention of disease. 
 
 London, 
 
 January, 1921. 
 
 4S0726 
 
 a 2 
 
PREFACE TO THE FIRST EDITION 
 
 One of the most remarkable features in the educational move- 
 ment of the present day has been the increased effort to diffuse 
 a knowledge of the relations which exist between our health and 
 the air we breathe, the water and food we consume, the soil we 
 tread and the buildings we occupy. Known under the various 
 current names of Sanitary Science, Public Health or Hygiene, 
 this subject involves an acquaintance with such diverse sciences 
 as physics, chemistry, geology, engineering, architecture, meteoro- 
 logy, epidemiology, bacteriology and statistics. To these, 
 strictly speaking, may be added the study of the law or those 
 legal enactments which concern the sanitary well-being of 
 communities. 
 
 When, therefore, the publishers asked us to prepare a small 
 work on this many-sided subject, to form one of their Science 
 Manuals, such as would present its facts and principles fully, 
 briefly, and yet in simple language suitable for both non-profes- 
 sional and professional readers, we were early confronted with the 
 difficulty of deciding what to include and what to omit. 
 
 We have endeavoured to consider the general laws of health, 
 the causes of disease and the means of combating them, in the 
 simplest language, and, by divesting them, where possible, of 
 scientific technicalities, to make clear, even to non-scientific 
 readers, those great natural laws and processes upon which our 
 healthy life so much depends. While doing so, we have felt 
 bound to be not unmindful of the wants of others, desirous of 
 entering more fully into the study of what should be a great and 
 practical subject in our national education. The work is not 
 to be regarded as a substitute for the regular and more advanced 
 
viii PREFACE TO THE FIRST EDITION. 
 
 books which discuss the subject of hygiene in its many bearings, 
 but rather is intended as an introductory manual for the use of 
 junior students or others, preparatory to a more extended and 
 practical study of public health work. 
 
 As regards chemical analysis, we have only attempted to give 
 such details as appeared absolutely necessary in order to make 
 the book useful to those capable of appreciating the meaning and 
 value of results. For their practical application, laboratory 
 experience and instruction are essential. In order to encourage 
 uniformity of international knowledge, the metric system of 
 weights and measures is used. 
 
 In view of the increasing public interest taken in facts and 
 laws concerning Weather, Climates, and Vital Statistics, short 
 chapters have been given upon these subjects, in non-technical 
 language as far as possible. 
 
 For illustrating some part of the text, we are indebted to 
 Mr. L. Casella for the use of drawings of various meteorological 
 instruments, and to Mrs. Bruce for several original diagrams. In 
 order to further illustrate the text, use has been made of four 
 diagrams published by the Local Government Board in their 
 annual reports. 
 
 Woolston, Southampton, 
 1894. 
 
CONTENTS 
 
 CHAPTER I. 
 
 AIR. 
 
 PACK 
 
 The composition and physical properties of air — Nitrogen — Oxygen — 
 Carbonic acid — Watery vapour — Weight — Expansibility — Diffusi- 
 bility — The impurities of air — Ammonia — Nitric and nitrous 
 acids — Carbonic acid — Carbonic oxide — Carburetted hydrogen — 
 Sulphurous acid — Sulphuretted hydrogen — Suspended matters — 
 Sewer and marsh emanations — Impurities from brickfields and 
 cement works — The theory and practice of ventilation — Impurities 
 due to respiration and artificial lighting — Amount of fresh air 
 necessary — Cubic space — Natural ventilation — Artificial ventilation 
 — Warming and heating — Practical examination of air and venti- 
 lation — Estimation of carbonic acid, organic and suspended matters 
 in air I - 53 
 
 CHAPTER II. 
 
 WATER. 
 
 The composition and physical properties of water — Quantity of water 
 required — Rain water — Springs and Rivers — Wells — Collection and 
 storage — Distribution — Cisterns — Action of water on lead pipes — 
 Quality of water supplies — Hardness and Softness — Impurities of 
 water — Effects of drinking impure water — Purification of water — 
 Filters — Collection of samples for analysis — Physical examination 
 of water — Qualitative examination — Quantitative examination — 
 Standard solutions — Total solids — Chlorides — Hardness — Free 
 and albuminoid Ammonia — Nitrites — Nitrates — Oxygen consumed 
 — Dissolved oxygen — Estimation of Lead — Estimation of Iron — 
 Examination of suspended matter and deposit — Bacteriological 
 examination — Collection of samples — Quantitative examination — 
 Qualitative examination — Interpretation of the results of a water 
 analysis 54 - 128 
 
X CONTENTS. 
 
 CHAPTER III. 
 
 FOOD. 
 
 PAGE 
 
 The classification, nature, and uses of food stuffs — Proteins- Fats— Carbo- 
 hydrates — Mineral salts — Vegetable acids — Vitamines — Nutritive 
 value of food stuffs — Energy obtainable from food — Diets — Calcu- 
 lation of diets — Hours of eating — Digestibility and cooking of food 
 — Diseases attributable to food — Meat — Fish — Eggs — Milk — Butter 
 — Cheese — Vegetable foods — Wheat — Bread — Biscuits — Macaroni 
 and Vermicelli — Barley — Rye — Oats — Rice — Maize — Peas and 
 Beans — Potatoes — Arrowroots — Tapioca — Sago — Lemons — 
 Vinegar — Tea — Coffee — Chocolate — Aerated waters — Alcohol — 
 Beer — Wine — Brandy — Whisky — Rum — Gin 129-206 
 
 CHAPTER IV. 
 
 SOILS, SITES, AND BUILDINGS. 
 
 Origin of soils — Moisture, air, and heat of soils — Selection of sites — 
 
 Construction and planning of dwelling-houses — Walls — Roofs' — 
 
 Ceilings — Floors — Hot and cold water supplies — Artisan dwellings 
 
 — Water-closets — Slop-closets — Trough-closets — Middens — Tub and 
 
 Pail closets— Schools— Hospitals 207-245 
 
 CHAPTER V. 
 
 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 Disposal of house and town refuse — Destructors — Nature and composi- 
 tion of sewage — Removal of sewage — Soil-pipes — House-drains — 
 Traps — Waste-pipes — Examination of drains — Sewers — Sewer air 
 — Ventilation of sewers — Pneumatic methods of sewage removal — 
 Disposal of sewage — Discharge into the sea — Discharge into rivers 
 — Cesspools — Purification of sewage — Chemical treatment — Land 
 treatment — Biological methods — Comparison of different methods 
 — Standardization of sewage — Camp sanitation 246-283 
 
 CHAPTER VI. 
 
 PERSONAL HYGIENE. 
 
 Habits — Eating — Drinking — Smoking — Sleep — Washing and bathing — 
 Soap — Baths — Clothing— Wool — Furs — Leather — Feathers — Silk 
 — Cotton— Flax — Jute — Hemp — Coir — Indiarubber — Selection of 
 clothes and boots — Exercise — Calculation of work done . . 284-298 
 
CONTENTS. xi 
 
 - 
 
 CHAPTER VII. 
 
 CHILD WELFARE AND SCHOOL HYGIENE. 
 
 PAGK 
 
 Nature of the child welfare movement — Health visitors — Ante-natal 
 clinics — Child welfare centres — The school child — Medical inspec- 
 tion of school children — Schools in relation to infectious diseases — 
 The closure of schools 299-306 
 
 CHAPTER VIII. 
 
 INFECTION AND DISINFECTION. 
 
 Micro-organisms — Nature of the infective process — Incubation and incu- 
 bation periods of disease— Immunity and protection — Vaccination — 
 Means of infection — Anthrax — Chicken-pox — Cerebro-spinal fever 
 — Cholera — Epidemic diarrhoea — Diphtheria — Dysentery — Enteric 
 fever — Encephalitis and poliomyelitis — Erysipelas — Influenza — 
 Malaria — Measles — Mumps — Whooping cough — Mediterranean 
 fever — Plague — Rabies — Relapsing fever — Scarlet fever — Simple 
 continued fever — Small-pox — Value of vaccination as a protective 
 against small-pox — Tetanus — Tuberculosis — Typhus — Yellow fever 
 — Notification of infectious diseases — Isolation — Disinfection — 
 Fumigation — Practical disinfection 3°7~3^3 
 
 CHAPTER IX. 
 
 PARASITES. 
 
 Ringworm — Microsporon furfur — Oidium albicans — Amoeba dysenterise 
 — Trypanosomes — Spirochetes — Leishmania — Coccidium — Plas- 
 modium malarias — Piroplasma — Acarus scabiei — Pediculi, or lice — 
 Fleas and bugs — Guinea-worm — Filaria sanguinis hominis — An- 
 chylostoma — Trichina spiralis — Thread-worms — Round-worms — 
 Tricocephalus dispar — Bilharzia haematobia — Tapeworm — Taenia 
 solium — Taenia mediocanellata — Bothriocephalus latus — Taenia 
 echinococcus 364-378 
 
 CHAPTER X. 
 
 CLIMATE AND WEATHER. 
 
 Varieties of climate— Causes of climate — Effects of climate— Tempera- 
 ture and means of observing temperature — Kinds of thermometers — 
 Where placed and how read — Sunshine— Rainfall and rain-gauges 
 — Humidity — Hygrometers — Calculation of the dew point — Evapo- 
 ration — Winds, and methods of showing and recording wind 
 
xii CONTENTS. 
 
 PAGE 
 
 velocities and directions — Clouds — Atmospheric pressure — Con- 
 struction and reading of barometers — Isobars and principles of 
 weather forecasting — Cyclones — Secondary cyclones — V-shaped de- 
 pressions — Anti-cyclones — Wedge-shaped isobars — Cols — Straight 
 isobars 379-414 
 
 CHAPTER XI. 
 
 VITAL STATISTICS. 
 
 Importance of vital statistics — Population — Influence of age and sex 
 distribution upon statistical returns — Birth and Marriage rates — 
 Death-rates — Causes of death — Influence of occupation — Mean age 
 at death — Probable duration of life — Life-tables, their construction 
 and importance — Tests of longevity — Value of statistical facts — 
 Probable error 415-443 
 
 CHAPTER XII. 
 
 SANITARY LAW. 
 
 Local sanitary areas and authorities — Definitions — Byelaws and regula- 
 tions — Cleansing and scavenging — Sewers and disposal of sewage 
 — House drainage, water-closets, privies, etc. — Water supply — 
 Nuisances — Unsound food — Horse-flesh — Bake-houses — Shell-fish 
 — Milk supplies — Adulteration of food — Infectious diseases — Canal 
 boats — Vans and tents — Cellar dwellings — Common lodging-houses 
 — Factories and workshops — Offensive trades — Rag flock — 
 Slaughter-houses . 444-527 
 
 Appendix 529 
 
 Index 537 
 
HYGIENE 
 
 CHAPTER I 
 
 AIR. 
 
 We are all familiar with the fact that the earth is surrounded on 
 all sides with a gaseous envelope, the atmosphere (from the two 
 Greek words, oxilq^ smoke, and or^cupa, a globe), or, as it is more 
 commonly called, the air. 
 
 This air, when pure, is free from colour, taste, or smell, and 
 is really a mechanical mixture of gases, possessing the properties 
 of weight, expansion, and diffusibility. That the air we breathe 
 is not a chemical compound, but only a mechanical mixture, is 
 known by the facts that the gases of which the air is made up do 
 not exist in it in their proper combining proportions, and that 
 the relative amounts of these gases in the air cannot be expressed 
 by any chemical formula. Moreover, on mixing the gases of 
 which air is composed, together in the same proportions as they 
 exist in air, there is no manifestation either of heat, electricity, 
 or change of volume, such as would result were air a chemical 
 combination. 
 
 The Composition and Physical Properties of Air. 
 
 The chemical composition of the dry atmosphere or air in 
 ioo measures or volumes may be roughly taken as being 79 of 
 nitrogen and 21 of oxygen with a small proportion of carbon 
 dioxide. If the calculation be made by weight, there would be in 
 100 parts of dry air, roughly 77 of nitrogen and 23 of oxygen. 
 As an average of many examinations, the composition of pure air 
 appears to be as follows : — 
 
 By Volume. By Weight. 
 
 Nitrogen 79*02 . . 76-84 
 
 Oxygen 20*94 • • 23*10 
 
 Carbon dioxide .... 0*04 . , . 0*06 
 
 IOO'OO ioo*oo 
 
 a 
 
2 [ &IS. 
 
 Besides the above gases, the air always contains a certain 
 quantity of watery vapour, together with various impurities. 
 
 Nitrogen is the main constituent of our atmosphere, and 
 appears to act as a diluent of the oxygen, evidently reducing 
 its strength and rapidity of action, much as water is used to dilute 
 spirits or wine. It is probable that the nitrogen of the air may 
 serve to supply plants with a certain amount of nourishment in 
 the form of oxides of nitrogen, which are washed down out of the 
 air into the soil after storms or rain, but on this point as yet very 
 little is known. 
 
 Pure nitrogen is a colourless, tasteless, and inodorous gas : 
 it is quite incombustible and incapable of supporting either com- 
 bustion or life ; it is from this latter peculiarity that foreign 
 chemists call it azote, a word derived from the Greek, meaning 
 u no life." We English people call it nitrogen, because it is the 
 element which gives birth, so to speak, to nitre. 
 
 Nitrogen can be easily prepared from the air, by removing, 
 by means of phosphorus, the oxygen with which it is mixed. A 
 piece of common phosphorus is wiped dry and placed in a 
 small porcelain capsule floating on some water contained in a 
 dish. A light is applied to the phosphorus and the dish quickly 
 covered with a glass bell jar. The phosphorus having a great 
 liking for oxygen will burn until the last trace of that gas is 
 removed from the air under the bell jar, forming as it burns 
 white fumes of phosphorus pentoxide. These gradually become 
 dissolved in the water, forming in it meta-phosphoric acid, 
 while the water itself slowly rises in the dish to occupy the 
 space originally taken up by the air, leaving the empty space 
 above the water filled by a colourless gas which is almost pure 
 nitrogen. 
 
 Nitrogen may also be isolated from the atmosphere by passing 
 air slowly over red-hot copper, which absorbs the oxygen and 
 leaves the nitrogen. About i per cent, of what for many years 
 was considered nitrogen in the air, is now known to be an elemen- 
 tary gas called argon, in association with other inert gases such as 
 neon, helium, krypton and xenon. 
 
 Oxygen. — Although nitrogen practically constitutes four-fifths 
 of the atmosphere, the most important constituent of the air is 
 oxygen. This gas, which when pure is clear and colourless, is 
 necessary for all forms of life ; all animals, if deprived of it, dying 
 at once. It is also needed for every kind of combustion, such as 
 the burning of wood or coal, and is necessary for every kind of 
 light except the electric light. Oxygen exists in the air in a free 
 state, and is not chemically combined with the nitrogen of the 
 atmosphere, but only mixed with it. 
 
CHEMICAL COMPOSITION OF AIR. 3 
 
 Oxygen can be abstracted and recovered from the air by heating 
 various metallic oxides and peroxides. For example, red lead, 
 heated, gives off oxygen and leaves litharge or plumbic oxide : 
 thus 2Pb 3 4 = 6PbO + 2 . Similarly, by the alternate conversion 
 of a substance called baric oxide into a still higher oxide or 
 peroxide by heating it in air and afterwards decomposing it by 
 further heat, back to the original compound, a continuous process 
 for the production of oxygen is obtained; thus 2p>a0 2 =2BaO + 2 . 
 The reason of being able to do this is due to the fact that barium 
 oxide contains 137 parts by weight of the metal barium, combined 
 with 16 parts by weight of oxygen, and if heated in purified air 
 absorbs 16 parts more of oxygen forming the barium peroxide. If 
 the temperature be still further raised, the extra 16 parts of oxygen 
 are given off, and the barium peroxide returns once more to barium 
 oxide, and can be further utilized again for the absorption of more 
 oxygen from the air. 
 
 A modification of oxygen occurs in small traces in the atmo- 
 sphere, and is known by the name ozone. This is a gas of 
 probably great importance and is a kind of intensely strong 
 oxygen. It is very plentiful in fresh pure air, and least so in 
 places where there is much organic matter, or where men or 
 animals are crowded together. Ozone is a powerful oxidizing 
 agent, and is produced whenever an electrical discharge takes 
 place in air due to the conversion of some of the atmospheric 
 oxygen into the extremely active modification, ozone, which, 
 however, can be reconverted into ordinary oxygen by the action 
 of heat. Ozone may be readily recognized by its odour, which is 
 so pungent that one volume present in 2\ million volumes of air 
 is said to be easily detected by the sense of smell. It is specially 
 noticeable in country and sea air. 
 
 The most usual test for detecting traces of ozone in air is to 
 expose strips of blotting paper moistened with a mixture of 
 potassium iodide and starch, when if any ozone be present a blue 
 tint is produced owing to the decomposition of the iodide and 
 the formation of a potassium oxide and iodide of starch. This 
 tint, however, is not very reliable, as there are often traces of 
 other gases present in the air which give the same result. If such 
 be suspected, in order to be quite sure that it is ozone only which 
 has turned the paper blue, it is necessary to use a second test, 
 which is to soak red litmus paper with a very dilute solution of 
 the iodide of potassium. The potassium oxide produced causes 
 an alkaline reaction, and turns the red paper to blue. Although 
 small traces of ozone constitute a powerful agent for the purifi- 
 cation of the air from waste organic matter, in larger quantities it 
 acts as a violent irritant to the eyes and nose. 
 
4 AIR. 
 
 Carbon Dioxide. — Samples of air, no matter where collected, 
 always contain another gas besides nitrogen and oxygen, called 
 carbon dioxide, and this usually to the extent of about 4 volumes 
 in 10,000 of air. Carbon dioxide is a clear colourless gas contain- 
 ing 12 parts by weight of carbon combined with 32 by weight of 
 oxygen. It is produced when carbon, which forms the greater 
 part of coal, is burnt. The carbon unites with oxygen, their 
 union producing both light and heat with the giving off of carbon 
 dioxide gas. For this reason, it is the invariable product of 
 the burning of animal and vegetable matter in the air, and is 
 the choke-damp which collects in mines after an explosion. It 
 is also largely given off by men and animals, as well as from the 
 earth, more particularly in volcanic districts. Under the influence 
 of sunlight, plants breathe in carbon dioxide, retaining the carbon 
 and setting free the oxygen. In the dark, this action of plant life 
 is reversed, the oxygen being absorbed and carbon dioxide given 
 off. Carbon dioxide, or as it is sometimes called carbonic acid, 
 exists largely in Nature in combination, forming compounds 
 called carbonates. It is readily obtained by adding dilute hydro- 
 chloric acid to a form of calcium carbonate such as marble or 
 limestone contained in a flask, and so arranged that the escaping 
 gas can be collected into a suitable vessel. The acid acts upon 
 the calcium carbonate, forming calcium chloride, water and carbon 
 dioxide ; this latter escapes as a gas while the two former remain 
 behind. 
 
 Carbon dioxide is faintly acid in taste and smell, and behaves in 
 an exactly opposite manner to oxygen, inasmuch as it can neither 
 support life nor combustion. It is a very heavy gas, being just 
 22 times heavier than hydrogen, which is the lightest of all gases. 
 It is soluble in water, but the volume so dissolved depends 
 largely upon temperature and pressure. The amount of carbon 
 dioxide present in the air varies according to place and season. 
 From 0*36 to 0*4 part per 1000 of air is found in towns, while 
 in country districts and on the tops of hills or mountains, about 
 0*3 part per 1000 of air has been the average amount found in 
 the atmosphere. In inhabited rooms and stables, of course much 
 larger quantities have been found. To the extent of 0*4 part 
 in 1000 of air carbon dioxide is a normal constituent of our 
 atmosphere, and unless it exceed that quantity it cannot be 
 considered an impurity. 
 
 Watery Vapour is always present in air. The presence of 
 this in the atmosphere is due to the fact that water evaporates at 
 all temperatures, so that a slow but invisible escape of water 
 vapour is taking place from the earth's surface at all times into 
 the air space which encircles the globe. If we leave a dish full 
 
WATERY VAPOUR IN AIR. 5 
 
 of water exposed to the air, it sooner or later dries up, because 
 the water goes away slowly in the form of vapour. This phe- 
 nomenon is sometimes spoken of as the tension or elastic force 
 of aqueous vapour, and is such that it can be measured or stated 
 to exercise pressure equal to so many inches of mercury. The 
 amount of watery vapour which the air can take up varies with 
 the temperature of the air, the greater the temperature the greater 
 the amount of water vapour which can be taken up. This 
 explains why water dries up much quicker in warm weather than 
 in cold. Expressed mathematically, it can be said that while 
 the temperature advances in arithmetical progression, the power 
 of the air to retain vapour increases with the rapidity of a geome- 
 trical series having a ratio of two. When air contains the full 
 amount of watery vapour for the given temperature it is said to 
 be saturated; and in proportion as it is more or less removed 
 from the point of saturation, and not in proportion to the precise 
 amount of water it contains, is air said to be dry or moist. Thus 
 if air can hold ioo parts of moisture, but actually only holds 75 
 parts, it is said to be only three-quarters moist, or to have 75 per 
 cent, of humidity. The amount of moisture in the air can be 
 determined by causing a current of air to flow slowly through 
 tubes containing hygroscopic substances such as anhydrous cal- 
 cium chloride or pumice moistened with concentrated sulphuric 
 acid, which have the power of taking up or absorbing water, and 
 then by weighing to note the increase in weight which has taken 
 place, and knowing the exact volume of air which has been 
 passed through, calculating the moisture present as a percentage. 
 It is, however, more usual to determine the atmospheric moisture 
 by means of instruments called "hygrometers," particulars of 
 which are described in a subsequent chapter upon climate and 
 weather. 
 
 While the amount of watery vapour in the air has a considerable 
 effect upon the temperature of a place, its presence is abso- 
 lutely necessary for life. A perfectly dry air not only would 
 be unbearable, but would quickly prove fatal to both plants and 
 animals. As a rule, the atmosphere contains from 1 to ij per 
 cent, of water in a state of vapour, or from 50 to 75 per cent, of 
 the amount required for complete saturation. If the quantity be 
 much above or below these limits, the air is either unpleasantly 
 moist or dry. 
 
 The air being really nothing more than a mixture of gases, 
 behaves exactly as and has the properties of a gas ; that is to say, 
 it has weight, expansibility, and diffusibility. Like any solid or 
 liquid, the air has weig'ht. That this is the case is shown by the 
 fact that if a glass globe of known capacity be taken, exhausted 
 
6 AIR. 
 
 of all air by means of an air-pump and then weighed, its weight 
 then will be less than it would be if air were allowed to enter it. 
 If the capacity of the globe be known, the difference between the 
 two weights is the weight of that volume of air. By a modification 
 of this method, and the exercise of certain precautions, the weight, 
 not only of air, but of other gases, has been accurately determined. 
 
 Since the air has weight, it gives rise to pressure according 
 to the same laws as those by which the weights of liquids 
 produce pressure. If we imagine an upright cylinder, some miles 
 in height, full of air and resting upon the ground with its top closed, 
 and consider the air contained in the bottom ten feet of the 
 cylinder, we can readily realize that this lower portion of air must 
 support the weight of all the air above it, and transmit that weight 
 to the ground beneath it, and also to the curved sides of the 
 cylinder which contain it, and that in a direction at right angles 
 to the surface. Thus the pressure of the air in this imaginary 
 cylinder increases from the top of the column to its base, and is 
 equal to the weight of that column. 
 
 If we regard the atmosphere as a kind of fluid sea, some 
 40 miles in depth, surrounding the earth on all sides, we can 
 realize that it exercises the same pressure as if it were a liquid 
 of very small density. This pressure will be at right angles to 
 any surface, and will lessen as we ascend from, and increase as we 
 descend to, the level of the earth. Since experiments show that 
 the weight of 100 cubic inches of air is no less than 31 grains, 
 it will be easily understood that the whole earth's atmosphere, 
 which has been estimated to be not less than 40 miles in height, 
 really exercises a very great pressure upon the earth's surface. 
 The exact amount of this atmospheric pressure was first deter- 
 mined by an experiment made in 1643 by Torricelli, which 
 may be explained as follows : — A glass tube, closed at one 
 end, is taken, having an internal diameter of \ inch, and being 
 a yard long. After filling it quite full of mercury, and then 
 stopping up its open end firmly with the finger, turn it upside 
 down, and insert its open end into a vessel containing mercury. 
 As soon as the finger is removed, the mercury will be seen to fall 
 slowly in the tube, until, if the observation be made in the south 
 of England, it stands about 30 inches higher than the surface of 
 the mercury in the vessel. This vertical column of mercury will 
 remain at 30 inches, in height, because it is prevented from 
 falling any lower in the tube by the counterbalancing weight or 
 pressure, as it is called, of the air. If this same experiment be 
 performed on the top of a mountain or high land, the length or 
 height of the mercurial column supported by the air will be less 
 than 30 inches, because at elevated . places the height and 
 
WEIGHT OF THE AIR. 7 
 
 consequently counterbalancing weight of the atmosphere is less 
 than at places at a lower level. 
 
 By a law of hydrostatics, the heights of two columns of liquids 
 in communication with each other are inversely as their densities ; 
 hence it follows that the pressure of the atmosphere is equal to 
 the weight of a column of mercury, the height of which is 30 
 inches. If, however, the weight of the atmosphere diminishes, 
 which it does do in elevated places, the height of the column 
 which it can sustain must also diminish. In the foregoing 
 experiment, the sectional area of the tube may be taken to be 
 equal to one square inch, and since the height of the column of 
 mercury is 30 inches, the mercurial column is really one of 30 
 cubic inches. As a cubic inch of mercury weighs 343 3 \ grains, 
 or as near as possible half a pound, the pressure of that column 
 of mercury on each square inch of surface is equal to 14! pounds. 
 On a square foot, this would give a pressure of nearly a ton ; and 
 as the average superficial area of an ordinary man is 16 square 
 feet, the pressure supported by such a man amounts to nearly 
 16 tons. This at first sight seems an impossible burden, but the 
 effect of this enormous force is equalized by the contrary and 
 equal pressure of it in all directions upon the body surface, 
 whereby we are rendered totally unconscious of its existence. 
 The instruments used for measuring atmospheric pressure are 
 called barometers ; their varieties and special features are discussed 
 in a subsequent chapter. 
 
 Though the total weight of the atmosphere must always be 
 the same, still its density, and consequently the pressure which 
 it exerts, will vary according to local conditions. The most 
 prominent of these conditions are its temperature and its 
 degree of dryness. Like every other gas, air expands with 
 heat, and assuming no variation in pressure, this is at the 
 rate of 5J7 or 0*00203 of its volume for each degree Fahren- 
 heit; or 273 or ©'00367 for each degree Centigrade. For this 
 reason, a given volume of air at 50 F. is lighter than the 
 same volume at 40 F. ; and a cubic foot of air at o° C. would 
 weigh just twice as much as a cubic foot of air at 273 C. 
 Similarly, moist air is lighter than dry air. The reason of this is 
 as follows : — Air is really a mixture of 4 volumes of nitrogen 
 (atomic weight being 14) and 1 volume of oxygen (atomic 
 weight being 16). Each volume of air, therefore, is represented 
 
 by i 3_i = 14*4. Now, moist air is air, plus water, in a 
 
 gaseous or vaporous state ; but water itself is a compound of 2 
 volumes of hydrogen (atomic weight 1) and 1 volume of oxygen, 
 and as a compound gas s occupying 2 volumes, is represented by 
 
8 AIR. 
 
 - — — : = g. That is to say, a volume of dry air weighs 14*4 
 
 2 
 and one of water vapour only weighs 9. These variations in the 
 weight of hot or cold, dry or moist air are indicated by corre- 
 sponding fallings or risings of the barometer, and explain why 
 in England the barometer rises during dry easterly winds and 
 usually falls with the damp westerly winds. 
 
 The Expansibility of air, which plays a very important part 
 in the theory and practice of ventilation, as we shall see later on, 
 is really dependent upon two conditions ; namely, the pressure 
 under which it is, as expressed by the barometer, and the tempe- 
 rature at the time being. For a due appreciation of this power 
 of air to constantly change its volume, it is necessary to under- 
 stand and apply the two physical laws of Boyle and Charles. 
 The law of Boyle is, that " the temperature remaining the same, 
 the volume of a given quantity of air or gas is inversely as the 
 pressure which it bears." In other words, this means that if a 
 cubic foot of air is measured at 29 inches of barometric pressure, 
 to know what it would measure, were the pressure 30 inches, 
 it must be multiplied by 29 and divided by 30. Or, that a 
 quantity of air which exactly measured 1 cubic foot at 29 inches 
 of barometric pressure would only measure 0*96 cubic foot had 
 the pressure been 30 inches, because 1 x §§ = 0*96 cubic foot. 
 
 The law of Charles is, that " assuming no change in pressure, 
 any gas or air expands or contracts 5 g T ('00203) of its volume 
 for every degree it is above or below 32 F. in temperature." 
 If the temperature be on the centigrade scale, the ratio of 
 expansion or contraction is ■— (-00367) for each degree above 
 or below o° C. In other words, this means that 491 volumes 
 of air at 32 F. become 492 at 33 , 493 at 34 , and so on. 
 That is, as 491 plus or minus the given temperature is to 
 491 plus or minus the required temperature, so is the given 
 volume to the required volume. As an example, we can say 
 100 volumes at 30 F. will become 104*09 volumes at 50 F. : 
 because as 491 — 2 (489) : 491 + 18 (509) : : 100 : x - 104*09 
 volumes. 
 
 In actual practice, it is usually needed to make these two 
 calculations or corrections together. For instance, suppose in a 
 room with the temperature at 40 F. and the barometer at 30 
 inches, the volume of air was 1000 cubic feet, what would be the 
 volume of that same air were the temperature to be raised to 
 6o° F. and the pressure fall to 29 inches? Using the two 
 equations combined, as follows — 
 
 30 _, 401 + 28 . . m 
 
 — X — r- x 1000 = To?? cubic feet, 
 
 29 491 -j- 8 ' J 
 
EXPANSIBILITY OF THE AIR. 9 
 
 we get that, under these altered conditions of pressure and tem- 
 perature, what before measured iooo cubic feet now measures 
 1075 cubic feet, consequently the excess of 75 cubic feet would 
 escape out of the room. 
 
 It is only by rightly comprehending the great property of the 
 atmosphere to expand or contract according to the above-men- 
 tioned laws, that we can fully appreciate the causation or produc- 
 tion of those movements of the air over larger or smaller regions 
 which we in everyday life call winds or draughts. They are due 
 to the simple fact, as already explained, that w r hen over some 
 large tract of land the air is warmed by the sun, it expands and 
 rises, while from adjoining regions colder and heavier masses of 
 air rush in to take its place. Similar but smaller movements 
 of air, due to varying degrees of heat, density, and pressure, are 
 constantly going on in and about our houses. It is the same 
 cause which makes the warm air over a fire go up the chimney 
 to be replaced by fresh and colder air entering by windows, doors, 
 and cracks. Whenever a room or house is inhabited by human 
 beings or warmed by lights and fires, a constant expansion of air 
 is going on with an escape of the excess volume by the chimneys 
 and doors or windows. By this means the equilibrium between 
 one part of a dwelling and another is constantly being disturbed, 
 and the air rarely if ever allowed to be absolutely still even over 
 the most limited area. 
 
 From what has already been said, it will be gathered that, 
 while the atmosphere has several constituents, each of them has 
 its own particular weight ; that while the carbon dioxide is heavier 
 than the oxygen, this again is lieavier than the nitrogen, and the 
 water vapour is lighter still. There is, however, no formation of 
 layers of the various constituents of the air, that is the heaviest 
 at or near the ground and the lightest above. Owing to the 
 diffusion of gases under well-known laws, the various constituents 
 of the atmosphere tend to mix one with the other, with the result 
 that we find them equably distributed. 
 
 The Diffusibility of a gas is well and easily shown by the 
 following simple experiment: Take a U-shaped tube some 18 
 inches long, fix it at one end by a cork to a porous cell such as 
 is used in electric batteries, and then fill the tube nearly full with 
 some water. Next make some hydrogen, and fill with it a bell 
 jar. If this bell jar containing the hydrogen be quickly placed 
 over the porous pot, the hydrogen gas so rapidly diffuses through 
 the pores of the cell or pot into the tube that the water is at 
 once driven down, and spurts out at the open end. So, again, if 
 we take two globes, and, having filled the lower one with carbon 
 dioxide and the upper with hydrogen, connect them together by a 
 
10 AIR. 
 
 tube, although the hydrogen was in the upper globe, yet, after a 
 short time, half of it will have gone down into the lower globe 
 and half of the carbon dioxide will have ascended into the upper 
 one. Now we know carbon dioxide to be just 22 times as heavy 
 as hydrogen, yet the power of diffusion is so great that it has over- 
 come the enormous force of gravity. 
 
 The rate at which this intermingling of gases can occur is 
 largely influenced by their weights (densities). So much so that, 
 according to the law of Graham, it is enunciated that " the force 
 of diffusion is inversely as the square roots of the densities of 
 gases." Thus, if we take two vessels of equal size, the one con- 
 taining oxygen and the other hydrogen, and separate them by 
 means of a porous plug, we shall find diffusion take place, and 
 this will be in the proportion of 4 parts of the hydrogen into the 
 oxygen to every 1 part of the oxygen into the hydrogen. This 
 exact ratio of diffusion is explained by the fact that the density 
 of the hydrogen is 1 as compared with the 16 of oxygen, hence 
 the force of the diffusion is inversely as the square root of these 
 numbers — that is, it is inversely as 1 is to 4, or just four times 
 as great in the one which has one-sixteenth the density of the 
 other. 
 
 It is this faculty of diffusion, possessed by all gases, which is the 
 chief cause by which the composition of the air is kept constant, 
 and which causes the carbon dioxide formed so freely in our large 
 towns and cities by combustion and breathing to be rapidly 
 removed from where it is formed to other parts, where the pro- 
 cesses of vegetation and sunlight can break it up into carbon for 
 the food of plant life and oxygen for the use of men. It is this 
 remarkable action of the green colouring matter of plants, called 
 chlorophyll, upon carbon dioxide, which is the great compen- 
 sating agency at work for keeping down the tendency of carbon 
 dioxide to increase, and whereby Nature gets rid ot what practi- 
 cally is the chief impurity in the air, with the result that the 
 carbon dioxide in the atmosphere at the top of a mountain is in 
 much the same proportion as in the air at its foot — namely, that 
 it rarely reaches a proportion of more than 0*04 per cent., an 
 amount which is quite harmless to human life. Supplementary to 
 the power of gaseous diffusion, we have the action of winds, which 
 scatter and diffuse over a large area many impurities of the air 
 which would be very hurtful if confined to any limited space. In 
 a similar but lesser sense, dew, rain, and snow may be regarded as 
 helping in the constant purification and dispersion of atmospheric 
 impurities. 
 
IMPURITIES OF THE AIR. II 
 
 The Impurities of the Air. 
 
 Although the examination of pure air indicates it only to 
 consist of nitrogen, oxygen, a definite amount of carbon dioxide, 
 not exceeding C04 per cent., and some watery vapour, the 
 majority of samples of ordinary air betray the presence in them 
 of various impurities, notably traces of ammonia, nitric acid, 
 nitrous acid, various compounds of carbon — chiefly carbon 
 dioxide, carbon monoxide and carburetted hydrogen, — with a 
 greater or less amount of suspended matter, such as soot, dust, 
 epithelial cells, vegetable fibres, wool and silk fibres, particles 
 of sand, chalk, or iron, and the minute forms of life. These 
 impurities of air are mainly the results either of combustion, 
 respiration, emanations from sewers, marshes, or graveyards, or else 
 the contaminations given off by manufactures and trade processes. 
 
 Ammonia is a compound containing 14 parts by weight ot 
 nitrogen along with 3 parts by weight of hydrogen. It is a colour- 
 less gas, marked by an intensely pungent odour, and quite unable 
 to support combustion. Although traces are usually present in 
 most air samples, it rarely exists in the atmosphere in greater 
 amount than 3 parts in ten million, and is formed in the main from 
 the decomposition of decaying nitrogenous matter. When present, 
 ammonia is usually in combination with some acid, such as nitric 
 or carbonic. Being readily soluble in water, ammonia is quickly 
 washed out of the air by rain, and carried down into the soil, in 
 which it affords a valuable food for plants. Chemically, ammonia 
 represents the main part of what is called the organic matter in 
 the air, and if dissolved in water, yields the so-termed albumi- 
 noid ammonia. 
 
 Nitric and Nitrous Acids are probably derived by the air in 
 small quantities from decaying nitrogenous matter, while, too, a 
 certain amount is produced in the air by the direct combination 
 of oxygen and nitrogen during electrical disturbances. These 
 acids, like ammonia, are washed down by rains into the soil, and 
 there serve in the fertilization of various forms of vegetation. 
 
 Carbon Dioxide has already been shown to exist to a limited 
 extent in pure air. This limit has usually been placed at 0*04 per 
 cent, or 4 parts in 10,000 of air; but it is probable that this limit 
 is too high, and that in the purest airs the natural amount of carbon 
 dioxide does not exceed 0*3 per 1000 volumes. Any carbon 
 dioxide present in air, therefore, over- and above 0*04 per cent., 
 must be regarded strictly as an atmospheric impurity. This gas 
 we know to be largely given off into the air by men and animals 
 during breathing, by all processes of combustion or putrefaction, 
 
12 AIR. 
 
 and by certain kinds of soil ; it is increased by fogs, but lessened 
 by rain, winds, vegetation, and ventilation. The amount in the 
 air is consequently variable. 
 
 In some places the air often contains as much as from 2 to 5 
 parts' per 1000; on the other hand, the air in a London street on 
 a breezy day has been found to have as little as 0*36 per 1000. 
 Carbon dioxide in its pure form is fatal when present to the 
 extent of 75 parts per 1000, while 15 parts per 1000 gives rise to 
 giddiness, faintness, headache, and shortness of breath ; anything 
 below 10 parts per 1000 appears to produce no effect immediately 
 on health. In fatal quantities the action of carbon dioxide is that 
 of a narcotic poison producing insensibility and deep sleep. The 
 amount of carbon dioxide given off by respiration is estimated 
 by deducting the amount present in the outside air, or, what is 
 usually the same thing, 0*04 per cent, from the total carbon dioxide 
 present. Thus, if in a hospital ward or schoolroom the air was 
 found to contain 0*78 of carbon dioxide per 1000 parts of air, 
 deducting 0*4 as being normally present in the atmosphere, we 
 should have 0*38 part per 1000 as a carbon dioxide impurity due 
 to respiration and other causes. We are all familiar with the heavy 
 unpleasant smell or stuffy feeling present in all ill-ventilated or 
 crowded rooms. In connection with this it has been observed that 
 anything under 0*2 part per 1000 over and above the 0*4 usually 
 present in the air — that is, a total of o*6 per 1000 — is not asso- 
 ciated with any atmospheric impurity capable of being perceived 
 by the sense of smell. For this reason, this quantity is regarded 
 as unavoidable and harmless, and, as such, a permissible impurity. 
 The moment the carbon dioxide exceeds this quantity, the ac- 
 companying organic and impure matters present in the air become 
 perceptible — so much so that the following scale has been pro- 
 posed, namely, u rather close" = 0*4; "close" = o*6 (ro total); 
 " very close " = o*8 (1*2 total) ; beyond this amount the sense of 
 smell does not seem able to distinguish. The temperature and 
 degree of moistness of the air have an influence upon the readi- 
 ness with which the smell of organic impurities is perceived. In 
 order to correctly judge the extent of atmospheric foulness by the 
 sense of smell, it is necessary that the observer should have been 
 at least some half-hour or so in the outer or fresh air, as the 
 sense of smell is very rapidly dulled by foul air — so much so that 
 the occupants of rooms containing impure air are rarely aware of 
 its state. 
 
 Though the prolonged stay in crowded or ill-ventilated rooms 
 whose atmosphere is markedly impure, as evidenced by a high 
 ratio of carbon dioxide, is invariably associated with headaches, 
 faintness, giddiness, etc., it is not to any organic fouling of the 
 
• CARBON DIOXIDE IN THE AIR. 1 3 
 
 air, or even to the carbon dioxide itself that these ill effects are 
 due. The outcome of recent inquiries indicates that the main 
 cause of the evil results which follow the breathing of used air is 
 the increase of moisture and heat combined with a diminution of the 
 oxygen, which is so characteristic of the air of ill-ventilated spaces. 
 In Hill and Flack's experiments, eight adults were imprisoned in 
 a small chamber holding about 3 cubic metres of air, and kept 
 there until the C0 2 reached from 3 to 4 per cent, and the oxygen 
 had fallen to 17 per cent, and the moisture risen to 95 per cent. 
 Although the discomfort was severe, it was relieved to an astonish- 
 ing extent by simply whisking the air by fans, and so cooling the 
 bodies of the imprisoned persons ; still greater relief was secured 
 by cooling the air by means of cold water allowed to circulate 
 through an attached radiator. These experiences indicate the 
 discomfort to have been due, not to chemical impurities, but to 
 excessive heat and humidity. 
 
 The continuous breathing of an undoubtedly vitiated atmo- 
 sphere is not less hurtful to health. It induces a general lowering 
 of the vital processes, with loss of strength and nutrition, to say 
 nothing of an indirect influence towards both physical deteriora- 
 tion and general moral degradation. It is only too probable that 
 to this cause, as much as to defective feeding, must be attributed 
 the impaired vitality and health of many of the poorer inhabitants 
 of our crowded towns and villages. 
 
 While, of the carbon compounds found as impurities in air, 
 carbon dioxide represents the. main impurity due to respiration 
 and combustion, there are several other gaseous impurities con- 
 stantly added to the air as the result of the combustion of coal, 
 coke, coal gas, etc. Among them are carbon monoxide, car- 
 buretted hydrogen, sulphurous acid, and sulphuretted hydrogen. 
 
 Carbon Monoxide is a gas produced by the combustion of 
 carbon in an atmosphere of carbon dioxide, and is frequently 
 formed on the surface of charcoal stoves not exposed to air 
 currents. This gas is extremely noxious, less than 0*3 volumes 
 per cent, being able to produce poisonous symptoms, such as 
 dizziness, headache, confusion of ideas, with a feeling as if a tight 
 band encircled the forehead and temples. In extreme cases, this 
 gas causes suffocation by displacing the oxygen out of the red cor- 
 puscles in the blood. The presence of carbon monoxide is always 
 a sign of imperfect combustion, such as occurs when coke is 
 burnt in an open grate, and is especially apt to be generated by 
 cast-iron stoves. This appears to be due to the fact that a 
 portion of the carbon dioxide evolved during the combustion of 
 carbon is changed by heated iron into carbon monoxide, and 
 that heated iron, more particularly cast iron, while generating 
 
14 AIR. ' 
 
 and absorbing this gas by its internal surface, permits it to diffuse 
 continuously from its external surface into the surrounding air. 
 It is chiefly owing to this fact that the employment of stoves in 
 this country has never been regarded with favour. 
 
 Carburetted Hydrogen, though often present as an impurity 
 in air, as the result of combustion of coal, is a comparatively 
 harmless gas. It is often present in small quantities in mines, 
 and appears to do no harm. In large quantities, such as 300 
 parts per 1000, it seems to produce some poisonous symptoms, 
 such as vomiting and convulsions. From its occasional presence 
 in the air over marshes, this gas is often called " marsh gas." 
 Another name for it is " methane." 
 
 Sulphur Dioxide and sulphuretted hydrogen are, among other 
 impurities, added to air by combustion processes. The former 
 is a constant impurity in the air of coal and gas burning towns, 
 where it often exists in sufficient quantity as to redden, after a 
 few hours' exposure, moist blue litmus paper. The presence of 
 this gas in the air of large towns is one of the chief causes of the 
 difficulty experienced in cultivating shrubs or trees ; while, too, 
 when washed down by rain, it materially retards the growth of 
 grass. 
 
 Sulphuretted Hydrogen, which is a disagreeably smelling gas, 
 may be found in the neighbourhood of gasworks, chemical 
 factories, sewers, and marshes. In mines it often exists from 
 the decomposition of iron pyrites. As a rule, this gas has no 
 ill effects upon health, but a few cases have been reported, 
 in which the continued breathing of this gas has given rise 
 to serious symptoms. In acute cases, these appear to be 
 those of a narcotic and convulsive poison; while in chronic 
 cases, more of the nature of anaemia, diarrhoea, and general 
 sickness. 
 
 Suspended Matter. — The impurities of the air which we have 
 so far considered are only gases, and, on the whole, generally 
 diffused or distributed; but, besides these, there are certain 
 impurities which are more or less solid, and only exist at or 
 near the spot where the cause for them is to be found. We are 
 all familiar with the fact that, if a beam of sunlight pass through a 
 chink or crevice into a darkened room, its course is made visible 
 to us by some of the light being reflected by minute particles of 
 suspended matter. The particles which comprise this suspended 
 matter, or solid impurities of the air, are of the most varied nature : 
 some of them are inorganic, some organic, some absolutely harm- 
 less, some truly hurtful. Except in certain places, such as on 
 the top of mountains or out at sea, it is difficult to find any air 
 which is absolutely free from all suspended matter, while in towns 
 
SUSPENDED MATTER IN THE AIR. 1 5 
 
 and factories the atmosphere is usually heavily laden with many 
 solid particles. How far these suspended matters or impurities 
 in the air will affect our health, depends much upon their quality 
 or nature, and not so much on their mere quantity ; but this 
 latter, in some cases, is not a negligible point. Chief among 
 the inorganic suspended matters of the air will be found fine 
 grains or particles of sand, coal or carbon, clay, common salt, 
 and oxides of iron. As a rule, these solid inorganic suspended 
 matters of the air, consisting of dust of various kinds, though 
 extremely injurious to health if in excess, are only so by virtue 
 of their mechanical irritating influences upon the eyes and lungs. 
 It is their physical conditions as to roughness, angularity, or 
 smoothness, rather than their mere nature, which influences their 
 power for evil. Various affections of the lungs, notably phthisis, 
 or consumption, have been traced among classes of work-people 
 as being due to the breathing in by them, during work, of the 
 finer dust products of their particular trades or businesses. For 
 instance, among tin-miners lung disease is prevalent, owing to 
 the fine particles of tin-dust inhaled by these workers ; similarly, 
 the fine dust from iron mechanically irritates the air-passages, and 
 gives rise to considerable ill-health among needle-makers, saw- 
 grinders, and cutlers. So, too, among potters, a peculiar asthmatic 
 cough is often set up in consequence of the continued breathing 
 of the finer clay dust. The makers of cement, grindstones, 
 and certain kinds of glass suffer in the same way. In white-lead 
 works, the lead dust gives rise to colic amongst the workers, 
 while workers in copper and brass foundries are subject to a 
 special form of non-periodic ague, and among match-makers 
 the fumes and particles of phosphorus used in making matches, 
 when inhaled, are apt to give rise to disease of the maxillary 
 bones. 
 
 The organic suspended impurities of the air vary, even more 
 than the inorganic, with the locality, both in kind and number. 
 Among the more common are starch cells, pollen grains, and 
 minute seeds of plants, pieces of wood, fine fragments of flax, 
 wool, cotton, and silk, together with fatty particles, scales of hair 
 or skin, and germs of disease. The majority of these are, of 
 course, harmless. That the disease known as hay fever or summer 
 catarrh is produced in many by the pollen from grasses is too 
 familiar to be doubted. In the carding-rooms of cotton, flax, 
 wool, and silk factories the finest dust from off the special fabrics 
 is often so great and so irritating in nature in the atmosphere of 
 the work-rooms that considerable ill-health results to those em- 
 ployed in them. Though it is somewhat disgusting to think 
 that particles of fat and scales of hair or skin are floating 
 
1 6 AIR. 
 
 about in the air, that such is the case is none the less true, and 
 is, moreover, a not infrequent means of carrying disease from 
 one person to another. Thus pus cells from ulcers and sores 
 may give rise to a very infective form of inflammation of the 
 eyes or even erysipelas, and the dried particles of expectoration 
 from the lungs of those suffering from consumption, floating in 
 the air, can convey that disease to those compelled to breathe 
 such tainted atmosphere : in a similar way, infective matter from 
 those sick with smallpox, scarlet fever, or measles may carry 
 these diseases to the healthy. Though the germs of disease thus 
 capable of being carried from one person to another by floating 
 through the air can only doubtfully be supposed to find any 
 nourishment and actually grow in the air, there is a possible risk 
 of their being able to retain their vitality while thus suspended in 
 the atmosphere. How soon or how readily they may infect any 
 one depends upon the different degrees of resisting power of the 
 particular germs and of the individual who may inhale them. 
 
 Numerous experimental observations have indicated that from 
 i to 22 micro-organisms per litre of air are present in the atmo- 
 sphere of four-roomed houses in excess of those present in the 
 outside air, and that in very small tenements, consisting of only 
 one or two rooms, the excess is from 6 to 240 per litre of air. 
 Without attaching too much importance to the actual number of 
 micro-organisms found or present in the air, it appears that the 
 proportion between the moulds and bacteria present is a matter 
 of considerable interest. The ratio of bacteria to moulds increases 
 with vitiation of the air, because bacteria come principally from 
 the walls, floors, and occupants of a room, while the moulds come 
 principally from the outside. While in the outer air, the bacteria 
 may stand to moulds in the ratio of only 2*5 to 1, in four-roomed 
 houses the ratio is often 21 to 1, in single-room tenements 49 to 
 1, and in crowded and imperfectly ventilated public rooms, such 
 as school, as much as 132 to 1. Experience suggests that in a 
 properly ventilated space the bacteria should not exceed moulds 
 in a greater ratio than as 30 to 1, and that the total number of 
 micro-organisms should not exceed 20 per litre of air. 
 
 Sewage Emanations. — Air rendered impure by emanations 
 from sewage, whether from drains, sewers, or cesspools, is un- 
 doubtedly capable of giving rise to ill-health, mo-re especially in 
 the form of sore throats (diphtheritic or otherwise), diarrhoea, and 
 gastro-intestinal disturbance. The composition of such air is 
 such that its oxygen is lessened, its carbon dioxide increased, and 
 that there is much organic matter together with varying amounts 
 of sulphuretted hydrogen present. The numbers of micro-organ- 
 isms present in the suspended matter of such air is not always 
 
THEORY AND PRACTICE OF VENTILATION. \J 
 
 increased. How far the bad effect following exposure to sewage- 
 polluted atmosphere is due to any one individual impurity is 
 uncertain, but the evidence is strong that either some specific 
 poison is carried by sewer emanations to the general atmosphere, 
 or else their effect is powerfully to predispose to disease. It is 
 probable that sewer emanations differ largely in their specific 
 powers for evil, according as to whether the generating sewer be 
 adequately ventilated or not, as evidenced by the good health 
 enjoyed by men working in well-ventilated and well-constructed 
 sewers as compared with those employed in sewers which are ill- 
 ventilated and otherwise faulty. 
 
 Marsh Emanations. — Marshes have long had ill-repute owing 
 to the prevalence of malaria in their vicinity. In the light 
 of modern knowledge, this connection of malaria with marshes 
 depends, not upon any special emanations of gases, but upon the 
 fact that water-logged lands and marshes afford suitable breeding- 
 places for certain kinds of gnats, or mosquitoes, which are neces- 
 sary for the diffusion of the malarial micro-organism from man 
 to man. 
 
 The air of Brickfields and Cement Works, though usually 
 characterized by a distinct smell, cannot be shown to be sanitarily 
 impure. The exact cause of the odours prevalent is not known, 
 and though the air issuing from the chimneys of furnaces and 
 kilns is rapidly fatal, so rapidly is it diffused and diluted that at a 
 very short distance it is quite respirable. The chief evil of the 
 smoke and gases escaping into the air from cement works appears 
 to be its destructive effect upon all adjacent vegetation. 
 
 In former years, much atmospheric pollution occurred in the 
 neighbourhood of copper, alkali, and chemical works generally, 
 from the pouring out of fumes of sulphurous, sulphuric, and 
 hydrochloric acids, along with sulphuretted hydrogen and ammo- 
 nium sulphide. At the present day this has to a great extent 
 been remedied. 
 
 The Theory and Practice of Ventilation. 
 
 From the preceding pages we have learnt that, while the aver- 
 age composition of pure air is practically constant, the nature of 
 the impurities in the atmosphere is less so. In the ordinary sense 
 in which the term ventilation is used, we may regard it as the 
 removal or dilution of all the impurities which can collect in the 
 air of inhabited rooms. These impurities, we have seen, may be 
 derived from various sources, such as respiration, exhalations 
 from the skin, the combustion of fires and lights, the presence of 
 filth, dirt, or putrefying matter, and even the escape of emanations 
 
1 8 AIR. 
 
 from sewers, drain-pipes, and other impurities under or outside 
 our houses. 
 
 In practice, we may limit the term ventilation to the dilution 
 or removal, by a supply of pure air, of the products of respiration 
 and of combustion in ordinary dwellings, coupled in the case of 
 hospitals with the additional impurities resulting from the presence 
 of sick persons. For the removal of all other air impurities, ven- 
 tilation ought not to be required, because, strictly speaking, these 
 should be avoided by the exercise of due cleanliness and the 
 maintenance of a proper system of drains and sewers, combined, 
 moreover, with a general attention to the sanitary condition of 
 the neighbourhood of our houses. Before proceeding, however, 
 to determine how much fresh air is required for the above-named 
 purpose, and as to how this supply can be best attained, it is 
 necessary to inquire with some detail what are the precise amounts 
 of the impurities added to the air of our houses as the results of 
 both respiration and artificial lighting and warming. To a large 
 extent these latter may be ignored, as the products of the com- 
 bustion of coal, used in artificial heating, escape for the most part 
 by the flue of a stove or by the chimney of an open grate, and as 
 such, do not materially add to the contamination of the atmo- 
 sphere of a room ; it is therefore unnecessary to enter into any 
 great detail regarding them. 
 
 Impurities due to Respiration. — It will be a material aid to 
 our conception of the amounts of the impurities added to the air 
 by respiration, if we recall the facts that while the air breathed 
 into our lungs contains about 79 per cent, of nitrogen, 21 per 
 cent, of oxygen, and 4 parts in 10,000 of carbon dioxide, the air 
 breathed out by the lungs contains 79 per cent, of nitrogen, about 
 16 per cent, of oxygen, 3 to 4 per cent, of carbon dioxide gas, and 
 some i-|- per cent, of watery vapour, the remainder consisting of 
 organic matter. In other words, this means that the oxygen has 
 been lessened by about one-fourth, the carbon dioxide increased 
 just about one hundred times, with the watery vapour, ammonia, 
 and organic matter also increased. 
 
 A healthy adult man at rest breathes from 14 to 18 times a 
 minute, and allowing that at each inspiration 25 cubic inches of 
 air are taken in, the total quantity of air which passes into and 
 out of the lungs in the twenty-four hours is about 648,000 cubic 
 inches or 15*6 cubic feet in each hour. This amount is, however, 
 largely increased by exertion, and may, in the case of a man doing 
 great labour, reach as much as some 1,600,000 cubic inches in the 
 same time. If we assume that the expired air contains only 4 per 
 cent, of carbon dioxide, the average man at rest evolves nearly 16 
 cubic feet of this gas in the twenty-four hours, or o'66 cubic foot 
 
IMPURITIES DUE TO ARTIFICIAL LIGHTING. 1 9 
 
 per hour; during hard work the amount evolved is something 
 like 37 cubic feet in twenty-four hours, or say i*6 cubic foot 
 per hour. 
 
 The quantity of watery vapour given off from the body is 
 greatly influenced not only by the different degrees of muscular 
 exertion and repose, but also under the ever-changing degrees of 
 moisture of the atmosphere. Speaking roughly, 10 ozs. are given 
 off by the lungs and some 20 ozs. by the skin in the day. This 
 is equivalent to about 550 grains per hour. If we assume the 
 average temperature of occupied rooms to be 6o° F., this means 
 enough moisture is given off by the human body every hour suffi- 
 cient to saturate 90 cubic feet of air. It is this tendency to become 
 saturated with moisture from the lungs and skin that makes 
 the air of crowded and unventilated rooms so uncomfortable. 
 Carnelley's experiments show that for every part of carbon 
 dioxide found in the air, 27 volumes, or i*i part by weight of 
 moisture, have been given off by each person inhabiting the 
 room. 
 
 As already explained, although the carbon dioxide added to 
 the air by respiration and other processes is not of itself a 
 very great impurity, yet it occurs in such constant relationship 
 with the rise in temperature and moisture as to be taken and 
 accepted as the most convenient index of the amount of the 
 general impurities added to the air by respiration. The amount 
 of this gas, then, given off daily by an ordinary man in repose 
 may be taken to be some 16 cubic feet, or o - 66 cubic foot per 
 hour ; in light work it is about C95 cubic foot, and in harder 
 work from r'6 to 1*95 cubic foot per hour. In the case of females, 
 the figure is about 0*5 cubic foot, and for a child 0*3 cubic foot; 
 or, as an average for a mixed community, o'6 cubic foot may be 
 accepted. 
 
 Impurities due to Artificial Lighting. — Turning now to the 
 question of the precise amounts of impurity added to the air con- 
 sequent upon artificial lighting, we find that the chief sources of 
 light are candles, oil, and coal gas, and that the chief products of 
 the more or less complete combustion of these illuminants are 
 carbon dioxide and water, with the addition, in the case of gas, of 
 several products of the combustion of sulphur. Now, the unit 
 adopted in this country for the measurement of all lights is a sperm 
 candle of a size known as " sixes," burning 120 grains per hour, 
 and which gives a light known as " one candle power." Such a 
 candle, on analysis, is found to contain — 
 
 Carbon 8o*o per cent. 
 
 Hydrogen 13-0 ,, 
 
 Oxygen 6*6 „ 
 
20 AIR. 
 
 and on complete combustion yields equal volumes of carbon 
 dioxide and water to the air, namely, 0*41 cubic foot. 
 
 The French unit of light is the light given out by one Carcel 
 burner, and equals 9*3 English standard candles. 
 
 What is known as Vernon Harcourt's standard flame gives 
 a light equal to that of one English standard candle. It consists 
 of an air-gas flame, 2\ inches in height, rising from an opening 
 \ inch in diameter. The flame is that of a mixture of air and 
 pentane : 576 volumes of air being mixed with one of liquid 
 pentane at 6o° F. ; or, if both are in the form of gas, 20 
 of air to 7 of pentane. Pentane is a hydrocarbon occurring 
 in petroleum and in the light oil obtainable from Cannel 
 coal. 
 
 Although various kinds of oil have been employed for illu- 
 minating purposes, paraffin, owing to its cheapness and high 
 illuminating value, is the only one in extensive use. Ordinary 
 paraffin, on analysis, gives the following composition : — 
 
 Carbon 86 'O per cent. 
 
 Hydrogen i4'o ,, 
 
 When burnt in the better kinds of lamp, the average consumption 
 per candle power of this oil is just 62 grains per hour, giving off 
 on combustion in that time 0*28 cubic foot of carbon dioxide and 
 o*2 2 of a cubic foot of water vapour. Formerly, rape-seed or 
 colza oil was largely used for lamps, but now it is replaced by 
 the mineral oils, paraffin and petroleum. Colza oil is remarkably 
 safe, but is expensive, and needs a special lamp for its use, owing 
 to its viscid nature and the difficulty in getting it to ascend the 
 wick. 
 
 All oil-lamps should have a suitable reservoir for the oil. This 
 should always be made of metal and not of glass or china, as 
 these latter break easily and cause the oil to escape. The reser- 
 voir ought to hold at least half a pint of oil for each wick in the 
 lamp, ft should never be filled quite up to the top, nor be 
 allowed to burn quite dry. If too full, the oil may overflow and 
 catch fire ; or when burnt to the last drop, the smouldering wick 
 may set fire to an explosive mixture of oil-vapour and air which 
 tends to collect inside the empty and hot lamp. Much of the 
 success of oil-lamps depends upon the proper regulation of the 
 draught to th£ flame by the length of the chimney and the placing 
 of a suitable inlet for air through a perforated metal plate below. 
 These are points usually seen to by the makers. Defects of this 
 nature check complete combustion of the oil, and are the cause 
 of the lamp smelling. All lamps should be provided with a 
 patent extinguisher. 
 
IMPURITIES DUE TO ARTIFICIAL LIGHTING. 21 
 
 The chief popular illuminant is gas. Ordinary gas is obtained 
 by the destructive distillation of coal, free from contact with the 
 air, and consists of a mixture of several gases, varying largely, of 
 course, upon the kind of coal used and the methods of purifica- 
 tion. The following statement of the analysis of two London gases 
 made by Professor Lewes may be accepted as fairly representing 
 the composition of coal gas generally : — 
 
 South Metropolitan The Gaslight and 
 
 Gas Company. Coke Company. 
 
 Hydrogen 50*16 
 
 Saturated hydrocarbons . . 36 '25 
 
 Unsaturated ,, . . 3*50 
 
 Carbon monoxide . . . 56S 
 
 Carbon dioxide .... 000 
 
 Nitrogen 4- 10 
 
 Oxygen 0*31 
 
 53-36 
 3269 
 
 3'5* 
 7 05 
 o - 6i 
 2-50 
 021 
 
 IOO'OO ICO'OO 
 
 These constituents of coal gas may be divided into three 
 groups — the illuminants, the diluents, and the impurities. The 
 illuminants are hydrocarbon gases, more particularly ethylene or 
 olefiant gas, acetylene, and benzene vapour; they constitute 
 about 4 per cent, by volume of the coal gas, and are referred to 
 above as unsaturated hydrocarbons. The diluents are gases which, 
 without conferring much luminosity on coal gas when burnt, yet 
 serve the important purpose of diluting down the heavy hydro- 
 carbons, which by themselves would yield a smoky flame. They 
 are hydrogen, carbon monoxide, and saturated hydrocarbons such 
 as methane or marsh gas. The impurities consist of nitrogen, 
 derived from a little air getting into the retorts when opened for 
 the purpose of recharging, and of some carbon dioxide, and 
 traces of sulphur compounds, which may have escaped removal 
 in the purifiers. It is forbidden by law that gas contain any 
 trace of sulphuretted hydrogen. In future all gas will be sold to 
 the public and judged by its calorific value in terms of thermal 
 units produced by the combustion of one cubic foot of the gas 
 measured at 6o° F. under a pressure of 30 inches of mercury 
 and saturated with watery vapour. 
 
 Every cubic foot of ordinary coal gas yields on combustion 
 roughly 0*52 cubic foot of carbon dioxide and 1*3 cubic foot of 
 watery vapour ; whilst the lighting power of gas per cubic foot 
 depends upon the particular burner employed. 
 
 Speaking generally, there are two principal kinds of burners 
 in use, namely, the flat-flame and Bunsen burners. Flat-flame 
 burners are of two chief kinds, known respectively as the 
 fish-tail and the bat's-wing. The fish-tail (Fig. 1) consists of 
 
22 
 
 AIF. 
 
 an iron nipple perforated by two holes, drilled so that the jets 
 of gas are inclined towards each other at an angle of 90 . A flat 
 flame is thus produced, and somewhat resembling the tail of a 
 fish. The bat's-wing (Fig. 2) consists of a similar nipple perfo- 
 rated by a fine slit, giving a flat, fanlike flame. In the best forms 
 of all kinds of burners now in use, steatite or pottery tops are 
 employed. The common metal and steatite burners in use 
 permit the current of gas to strike against the orifice without any 
 control or regulation, but in the numerous patented forms of both 
 fish-tail or bat's-wing burner, a certain mechanical obstruction 
 or governor is inserted, which breaks or retards the gas current, 
 to ensure more complete combustion. The illuminating power 
 of a good fish-tail or bat's-wing burner equals 16 candles, with 
 an hourly consumption of something like 4 or 5 cubic feet of gas 
 per hour ; but the great majority of flat-flame burners in common 
 use of the size known as 4 or 5, and popularly supposed to 
 
 
 Fig. i. — Fish-tail burner. 
 
 Fig. 2. — Bat's-wing burner. 
 
 consume respectively 4 and 5 cubic feet of gas per hour, really 
 consume nearly double that amount of gas, and at the same time 
 yield an extremely low degree of light. 
 
 The actual products of combustion given off by gas will, of 
 course, vary much with the quality of the gas used and the com- 
 pleteness of the process. The usual products of the combustion 
 of gas are : carbon dioxide, carbon monoxide, compounds of 
 ammonia, watery vapour, and various compounds of sulphur. 
 These latter, if present, are particularly injurious to health, but there 
 is reason to believe that their existence in gas-lit rooms has been 
 much exaggerated. For every 100 cubic feet of gas consumed, 
 containing 20 grains of sulphur, there would be 0*032 of a cubic 
 foot of sulphur dioxide formed, while with an impurer gas contain- 
 ing 30 grains of sulphur per 100 cubic feet, the sulphur dioxide 
 resulting would amount to 0*048 cubic foot. Except under very 
 exceptional circumstances, ventilation would reduce these quanti- 
 ties in nearly the same ratio as the carbon dioxide, the total volume 
 of sulphur dioxide due to the combustion of the gas being reduced 
 to very minute traces. The presence of undue quantities of 
 
PRODUCTS OF THE COMBUSTION OF GAS. 
 
 23 
 
 sulphur dioxide in the air as the result of burning gas is chiefly 
 productive of injury to- health owing to the fact that by com- 
 bining with the moisture and oxygen present in the atmosphere it 
 becomes slowly converted into sulphuric acid. This contingency 
 is likely to be of rare occurrence in inhabited rooms, as it cannot 
 take place unless the percentage of water vapour present in the 
 air be at saturation point, an event of most unlikely occurrence. 
 
 If we adopt, as is usual, the amount of carbon dioxide yielded 
 as our measure of vitiation of the atmosphere, we find that each 
 cubic foot of gas burnt per hour on an average vitiates as much air 
 as would be rendered impure by the respiration of an individual ; 
 for, as has already been stated, an adult exhales o*6 cubic foot of 
 carbon dioxide per hour, and 1 cubic foot of ordinary gas yields 
 on combustion 0*52 cubic foot of carbon dioxide. 
 
 The relative amounts of oxygen removed from the air and 
 carbon dioxide and water vapour yielded by various forms of 
 artificial light in order to give an illumination equal to 1 6 candles, 
 is given in the following table, in which is also incorporated the 
 number of adults who would exhale the same amount of carbon 
 dioxide in the same time : — 
 
 
 Sperm 
 candles. 
 
 Paraffin oil. 
 
 Gas burned in 
 
 
 Flat-flame 
 burners. 
 
 Incandescent 
 gas-lights. 
 
 Amount burnt .... 
 Oxygen removed 
 Moisture produced . 
 Carbon dioxide produced . 
 Air vitiation equal to adults 
 
 1740 grs. 
 
 9*63 C. ft. 
 
 6-56 c. ft. 
 
 6-56 c. ft. 
 
 no 
 
 992 grs. 
 6*24 c. ft. 
 3'50 C. ft. 
 
 4 '45 c. ft. 
 7*5 
 
 5*5 c. ft. 
 6-50 c. ft. 
 7'35 c. ft. 
 3-50 c. ft. 
 5*o 
 
 3*o c. ft. 
 3'8 c. ft. 
 4*6 c. ft. 
 2'0 c. ft. 
 3'o 
 
 If we know, therefore, the amount of impairment and vitiation 
 of the atmosphere produced by one gas-burner, lamp, or candle, 
 it is easy to arrive at the relative contaminating effect which the 
 various artificial lights produce on the air of a dwelling-room. 
 It follows, therefore, that a system of ventilation designed for a 
 room when no artificial light is used, cannot be expected to be 
 successful when a number of candles, lamps, or gas-jets are burn- 
 ing. Although the contaminations, especially in the case of gas, 
 are very great, it is estimated that for their proper dilution the 
 amount of fresh air supply in relation to the carbon dioxide evolved 
 need not be so great in their case as for breath impurities, a 
 supply of 900 cubic feet of fresh air for every cubic foot of 
 
24 AIR. 
 
 carbon dioxide per hour, evolved by the light, being deemed 
 sufficient, and as every cubic foot of gas evolves 0*52 cubic foot 
 of carbon dioxide, it results that, for every cubic foot of coal-gas 
 burned, something like 450 cubic feet of fresh air should be 
 supplied per hour in addition to those needed to dilute the respi- 
 ratory impurities. 
 
 As judged by the rules already laid down that the vitiation of 
 the air of any limited space, such as a room, is measurable by 
 the heat and moisture and carbon dioxide generated, it appears 
 that candles are most injurious to health and comfort, oil-lamps 
 less so, and gas the least of all. Practical experience does not 
 bear this out, since the discomfort and sense of oppression felt 
 by the use of gas in rooms is much greater than that following 
 the use of oil or candles. The explanation of this discrepancy 
 between science and everyday life probably is that, in attempting 
 to light a room with either candles or oil, we are content with 
 much less intense, but a more localized, illumination than when 
 we employ gas. Say we have a room 16 feet long, 12 feet wide, 
 and 10 feet high, and requiring for proper illumination a light 
 equal to at least 32 candle-power. In such a room, if using 
 candles, we should in all likelihood be content with a couple of 
 candles placed near us to read or work, and not place 32 candles 
 in different places to give a diffused yet sufficient light. It is 
 obvious that with only two or three candles we should have less 
 air vitiation produced than if 32 were burning. 
 
 Illuminants not only yield actual impurities to the air, but also 
 heat it. The amount of light evolved depends entirely upon the 
 heat generated, simply because much of the light evolved is 
 dependent upon the incandescence or excessive heating of the 
 solid particles of carbon in the flame ; and the greater the tem- 
 perature to which these solid matters are raised the brighter the 
 light. This is one of the reasons why gas is tested by its 
 calorific value or in terms of thermal units. 
 
 The more recent improvements in gas-lighting have done 
 much to lessen the vitiation of the air by the products of com- 
 bustion in dwelling-houses : partly by ensuring a more complete 
 combustion of the gas and partly by arrangements for the rapid 
 removal of their engendered impurities. The former is secured 
 by arranging the burners upon the principle of the Bunsen burner, 
 in which, the gas being mixed with atmospheric air, the com- 
 bustion is nearly perfect, and consequently no unburnt particles 
 either of carbon or other matter escape unconsumed to foul 
 the air. The incandescent gas-light as now in the market is 
 based upon this principle, the light being derived from the in- 
 candescence or glow of a thin veil or mantle exposed to a Bunsen 
 
PRODUCTS OF THE COMBUSTION OF GAS. 2$ 
 
 flame. This light is very brilliant, economical in its consumption 
 of gas, and hygienically sound ; its practical defect is its great 
 whiteness and dazzling illuminating power. 
 
 Acetylene has come into some prominence lately as an illumi- 
 nant. It is derived from the interaction of water on calcium car- 
 bide. Compared with ordinary coal gas of 16 candle-power, 
 acetylene shows an illuminating power of 240 candles. Although 
 yielding a very brilliant light, the use of acetylene needs absolute 
 soundness of gas-fittings inside the house, as an escape of this 
 illuminant is liable to be accompanied by grave consequences. 
 When inhaled it acts forcibly and injuriously on the respiratory 
 functions of the haemoglobin of the blood, and within the limits 
 of 3 per cent, acetylene and 82 per cent, of air may lead to 
 explosions. 
 
 Some municipalities and gas companies have taken up the 
 use of so-called " water-gas." This is made by passing steam 
 through incandescent coke or anthracite coal ; it is further ren- 
 dered luminous for lighting purposes by a process known as 
 " carburetting," in which vaporized mineral oil is added to the 
 gas. Carburetted water-gas has a distinct smell like that of coal- 
 gas, and is usually highly charged with carbon monoxide, which 
 may amount to as much as 35 per cent. The particular danger 
 associated with the use of water-gas is that of poisoning by carbon 
 monoxide, and necessitates the use of most accurately made gas- 
 fittings. Dowson gas is a modified form of water-gas, and presents 
 the same disabilities. 
 
 The most hygienic form of light which can be imagined is, of 
 course, the electric incandescent lamp, which, other than giving 
 out some heat, yields no impurities to the air. The arc electric 
 light, which is unenclosed, is said to vitiate the air by the 
 formation of nitric acid, but even if so, its effects in this direction 
 are much less hurtful than gas, oil, or candles. 
 
 Quantity of Fresh Air needed. — Having now learnt something 
 of the impurities poured into the air of our homes as the result of 
 both respiration and artificial lighting, we have next to learn how 
 much fresh air is required to dilute and remove those impurities, 
 and how best this supply can be attained. 
 
 It has already been stated that an average adult exhales or 
 gives off to the air o* 6 cubic foot of carbon dioxide per hour, and 
 since anything below or just up to this amount of carbon dioxide 
 in' 1000 cubic feet of air in a room is indistinguishable by the 
 sense of smell from the ordinary outer or pure atmosphere, that 
 limit or amount of carbon dioxide can be regarded as the standard 
 of efficient ventilation. But 1000 cubic feet of pure air contain 
 0*4 cubic foot of carbon dioxide, therefore they can take up or 
 
26 AIR. 
 
 receive 0*2 cubic foot more of carbon dioxide and not contain an 
 excess over the standard limit of o*6 cubic foot. The quantity of 
 o'2 cubic foot of carbon dioxide per 1000 of air, or 0*0002 per 
 cubic foot of air, is commonly spoken of as the standard permissible 
 impurity. Based upon these facts, the late Professor de Chau- 
 mont suggested a very simple formula to determine the volume of 
 pure air requisite each hour to keep the carbon dioxide in the air 
 of any inhabited room at this limit of o'6 part per 1000 volumes. 
 Let A be the quantity of carbon dioxide given off per hour per 
 head. Let B be the proposed permissible maximum quantity of 
 carbon dioxide in the air of the room per 1000 cubic feet of air. 
 Let C be the amount of carbon dioxide present in 1000 cubic feet 
 of fresh air. Let D be the amount of fresh air required per head 
 each hour to maintain the standard quantity B, expressed in 
 
 thousands of cubic feet. Then ^ ~ = D, or ^ — = D, and 
 
 ±> — L/ a — 04 
 
 if we take B to be o'6 cubic foot per 1000 of air, we get the 
 
 o'6 o*6 
 
 formula to read thus : — — = D, or — = -z in thousands of 
 
 o*6 — 0*4 0*2 
 
 cubic feet of air needed each hour per head. 
 
 If it be the case of an individual doing light work in a room, 
 
 and giving off say 0*95 cubic foot of carbon dioxide per hour, we 
 
 should have A = 0*95, and the formula stands as — - — ^-- = D, 
 
 o'6 — o*4 
 
 or, in other words, D would equal 4750 cubic feet of fresh air 
 required hourly in order to keep the impurity down to the standard 
 limit. 
 
 The formula can be used in another way. Suppose the air 
 in a room has been found to contain i'a volume of carbon dioxide 
 per 1000 — that is, o*oot2 per cubic foot of air — and it is required 
 to know how many cubic feet of fresh air have been hourly 
 delivered per head. In this case, the actually observed air im- 
 purity, namely, 1*2, takes the place of the maximum permissible 
 
 impurity; that is, B now equals 1*2, hence we get -s-^-p = D, 
 
 o*6 _ o"6 
 
 or r2 __ — = D,or— = D. That is, 750 cubic feet of air 
 
 have been actually delivered per hour in the room. 
 
 By a transposition of the same formula we can calculate the 
 probable condition of the atmosphere of a room into which a 
 given quantity of air has been or is being supplied. The formula 
 
 would then stand thus : ^ + C = B. If in a room containing 
 
 5 persons, each giving off o'6 cubic foot of C0 2 hourly, we assume 
 
CALCULATIONS OF FRESH AIR NEEDED. 2J 
 
 1500 or 1 '5 thousand cubic feet of air to have been supplied per 
 
 c X 0*6 
 hour and to represent D, we get f- 0*4 = B, or B = 2*4 ; 
 
 %J 
 
 that is, 2 parts of carbon dioxide per 1000 of air will be present 
 in the air of the room over and above what is normally present in 
 the outer air. In some cases, of course, A would not be repre- 
 sented by o'6 cubic foot, as say, in the case of an adult man doing 
 hard work ; the amount of carbon dioxide given off by him per 
 hour would be as much as 1*96, or nearly 2 cubic feet, 
 and in the case of children, might be as low as 0*4 per hour. 
 The general statement, however, of the formula remains the 
 same. 
 
 A consideration of these facts indicates that if we wish to 
 keep the air of our homes at the standard degree of purity, it 
 should not contain more than o*6 part of carbon dioxide in 1000, 
 or 0*2 part in 1000 over the average in samples of ordinary air. 
 Further, in order to keep the carbon dioxide below o*6 part per 
 1000, it is necessary to change the atmosphere by supplying fresh 
 air, and this, as worked out, means a supply of 3000 cubic feet of 
 fresh air every hour for each person. The following table gives 
 the amounts of carbon dioxide given off by various persons per 
 hour under varying conditions, and, corresponding to them, the 
 quantities of fresh air theoretically needed : — 
 
 Adult male in very hard work . 
 ,, », in light work . 
 
 „ ,, at rest 
 
 CO 2 given off 
 
 per hour in 
 
 cubic feet. 
 
 I "96 
 
 Fresh air needed 
 hourly per head in 
 cubic feet. 
 . 9800 
 
 o'95 
 072 
 
 o'6o 
 
 • • .4750 
 . . 360O 
 . 3OOO 
 
 0*40 
 
 . 2000 
 
 o'6o 
 
 . 3000 
 
 Adult female at rest. 
 
 Children 
 
 Average of a mixed community 
 
 Carnelley, Haldane, and Anderson, basing their opinion not 
 only upon the average presence of carbon dioxide in the air, but 
 also upon the organic matter and number of micro-organisms, 
 proposed that instead of taking o'6 cubic foot of carbon dioxide 
 per 1000 as the limit, that the standard should be i*o for dwellings 
 and 1*3 for schools. 
 
 In mines as much as 6000 cubic feet per hour have been 
 proposed to ensure maximum energy in those working below 
 ground. In hospitals and for the sick generally, the maximum 
 amount of fresh air ought to be at least one-fourth more than 
 that allowed in health. If 3600 cubic feet per hour be accepted 
 as a general average supply for health, we may admit the needs 
 of the sick to be at least 4500 cubic feet per hour. 
 
 As regards the amount of fresh air required for animals, the 
 
28 AIR. 
 
 following table gives theoretical quantities of air as worked out 
 by various observers : — 
 
 Cubic feet per head Cubic feet 
 
 per hour. of space. 
 
 Cows 8000 
 
 Calves 3000 
 
 Horses 8000 
 
 Dogs 500 
 
 Pigs 3500 
 
 Cats 400 
 
 1600 
 600 
 
 1600 
 100 
 
 700 
 80 
 
 It is probable that these amounts are too small ; at least 25 
 cubic feet per pound of body weight ought to be supplied, as, 
 like 1 human beings, all animals thrive Best in well-ventilated 
 places. 
 
 Cubic Air-Space required. — Though theoretical considerations 
 may indicate that certain quantities of fresh air are needed per 
 hour per head in order to maintain the atmosphere at a degree of 
 sweetness compatible with health, yet when it comes to actual 
 practice, certain difficulties are met with. Experience shows that 
 under the ordinary climatic conditions of this country, the air 
 of a room cannot be changed more than three times an hour 
 without causing much inconvenience by draught. This means 
 that if we are to have 3000 cubic feet of fresh air each hour, 
 we must each have a cubic air-space of at least 1000 cubic feet. 
 If it be less than this, say, 100 cubic feet of space, then in order 
 to deliver 3000 cubic feet of air hourly, the renewal of air will 
 have to be thirty times in that period of time, and this we know, 
 owing to the formation of draughts, would be unbearable unless 
 the incoming air be warmed. At 6o° F. air, moving at the rate of 
 two feet per second, is barely perceptible ; at three feet it is more 
 so ; and above this it becomes a draught. At 70 F. the velocity 
 of the air-current can be even greater without being noticed. 
 The question arises, what then is the least amount of cubic space 
 through which the standard quantity of fresh air can be passed 
 without causing inconvenience from draught? By experiments 
 made with the best mechanical means and artificial heat, Petten- 
 kofer determined that in an air-space of 424 cubic feet, 2640 
 cubic feet of air could be drawn through in an hour without per- 
 ceptible draught ; this was equivalent to a change of air at the 
 rate of six times an hour. But in ordinary circumstances, and 
 without artificial methods of warming the incoming air, a renewal 
 of air in a room at the rate of six times an hour in this 
 climate could not be tolerated. In fact, a change of air three 
 or four times an hour is about as much as can be borne, and 
 
CUBIC SPACE. 29 
 
 this brings us to an original air-space of close upon 1000 
 cubic feet. Whatever the amount of air required hourly per 
 head, the cubic space per head should be in the proportion of 
 one-third this amount. The moment we attempt to ventilate a 
 small space, say 500 cubic feet, by ordinary or so-called natural 
 means of ventilation, the difficulties arise not so much from the 
 actual rate of movement of the general mass of air, as from the 
 velocity with which the air enters at the openings and the near- 
 ness and relative position of these to the persons occupying the 
 space. In order to supply 3000 cubic feet per hour, in each 
 minute ^-|f- = 50 cubic feet must enter, and in each second f$ 
 = 0*83 cubic foot. If the inlet opening be a square foot, the 
 velocity of a current that would introduce 0*83 cubic foot would 
 of course be 0*83 linear foot per second. Taking a room with 
 3300 cubic feet of air to be delivered per hour, and having an 
 inlet or opening of 12 square inches, the rate of movement of the 
 incoming air would be 10 feet per second, or nearly seven miles 
 per hour ; the room being so small, the rapid current of air could 
 not be broken up, diffused, and mixed with the larger mass in the 
 chamber sufficiently before striking its occupants and giving rise 
 to a feeling of draught. If, of course, the room were just double 
 the size, say 1000 cubic feet, or the apertures of inlet be enlarged, 
 the movement would be less felt ; but if the space be small, say 
 500 cubic feet, any enlargement of the inlets renders them alto- 
 gether too large in proportion to be practically allowable. 
 
 Even' with some artificial arrangements, experience goes to 
 show that in small spaces the air becomes much more impure 
 than in large ones ; the reason being that in small spaces, even 
 if large quantities of fresh air are being supplied, little uniform 
 diffusion occurs, as owing to the frequent establishment of direct 
 currents between inlets and outlets, large amounts of the fresh 
 air escape without being made use of; also that in small spaces 
 ventilation gets stopped much more readily than in larger ones, 
 and if this occur, the ratio of increase of impurities is far greater 
 in the small rooms than in the larger. 
 
 The amount of air-space which these theoretical considera- 
 tions indicate ought at least to be given to each adult, appears to 
 be not less than 1000 cubic feet, but this is undoubtedly much in 
 excess of what most people are able to get. Excellent as is the 
 standard laid down by de Chaumont, prolonged experience shows 
 it to be practically impossible of attainment in this country under 
 ordinary circumstances. We, therefore, are disposed to accept the 
 standard limit suggested by Carnelley as being one most likely to 
 meet ordinary conditions. If we take that as being a maximum 
 of i*o cubic foot of carbon dioxide per 1000 cubic feet of air, we 
 
30 AIR. 
 
 get a permissible respiratory impurity of 06 in place of 0*2 cubic 
 foot as suggested by de Chaumont. This means a need of 1000 
 cubic feet of fresh air each hour in place of 3000, and assuming 
 that the necessary change of air cannot be made oftener than 
 three times an hour, we find the minimum air-space for each adult 
 will then stand at about 350 cubic feet; this we find to be closely 
 in accord with present-day conditions. For humified weaving- 
 sheds and workshops, the regulations of the Home Office permit 
 a maximum of 9 volumes of carbon dioxide in 10,000 of air 
 when no gas is burning. This means a permissible respiratory 
 vitiation of 0*5 per 1000 of air. A departmental Committee, 
 dealing with the same subject, went so far as to recommend an 
 increase of permissible C0 2 to 12 volumes by day and 20 by 
 night with gas burning, for every 10,000 volumes of air. We 
 confess to grave doubts whether this reduction of ventilation 
 standards in places of this kind is wise, though we are fully alive 
 to the difficulties in the way of securing the lesser degrees of 
 vitiation as laid down by earlier writers on the subject. 
 
 In the majority of rooms occupied by the poorest classes, 
 the cubic space available for each occupant is rarely more than 
 250 cubic feet, while in the lodging-houses of the larger towns the 
 allowance is not more than 300 cubic feet. In elementary schools 
 the regulation minimum allowance is 100 to 120 cubic feet per head. 
 In factories and workshops, 250 cubic feet of air-space are required 
 per head during the day, and 400 cubic feet during overtime. 
 For soldiers in barracks, 600 cubic feet is the least space allowed. 
 In hospitals, the cubic space ought to be quite 1500 cubic feet, 
 if not nearly 2000 ; and the minimum floor-space 100 square 
 feet. In all rooms with more than one occupant, it is necessary 
 that a certain floor-space should be allotted to each person, for 
 the purpose of allowing currents of air to remove emanations 
 from one individual without interfering with his neighbour. For 
 this reason, in all cases, whether private houses, barracks, hospitals, 
 or other public buildings, a good rule is to secure as the lowest 
 limit of floor-space an area not less than one-twelfth of the cubic 
 space. Moreover, it is important to remember that mere height 
 in a room is of no advantage unless combined with means for 
 removing the heated air from the upper part, and that mere cubic 
 space cannot take the place of change or renewal of air, for even 
 the largest of air-spaces can only supply sufficient air for a limited 
 time, after which the same amount of fresh air must be supplied. 
 This 350 cubic feet of space for one adult would be sufficient if 
 the air in it were changed three times an hour, but in the absence 
 of any renewal, 350 cubic feet of air would only be sufficient for 
 one person for 20 minutes. Of course, it must not be overlooked 
 
NATURAL VENTILATION. 3 I 
 
 that the source from which supplies of fresh air are drawn must 
 be pure ; and that, notwithstanding the fact of the standard quan- 
 tity of air being delivered hourly per head, no claim could be 
 made in such case for the existence of proper ventilation if the 
 incoming volumes of air were in any way derived from contami- 
 nated or impure sources. In a similar way, attention needs to be 
 directed to the actual temperature of the air entering a chamber ; 
 in summer it may need to be cooled as much as it requires to 
 be warmed in winter, the reason being that the actual tempe- 
 rature of an air-current is the main factor in our appreciation of 
 its velocity. Owing to the fact that expired or foul air is warmer 
 and lighter than pure air, it tends to rise to the upper parts of a 
 room, for which reason, to ensure free ventilation, the outlets for 
 impure air should be at or near the highest point, and the inlets, 
 arranged so as not only to avoid draughts blowing upon the 
 occupants, but also to secure equal diffusion of the air, should all 
 be given an upward direction, whereby the tendency of the fresh 
 masses of air, particularly if cool, to fall to a lower level, is mini- 
 mized as far as possible. 
 
 We have already denned ventilation as the removal or dilution, 
 by a supply of pure air, of all the impurities which can collect in 
 the air of inhabited rooms or houses. The next matter which 
 demands consideration is how the ventilation of a room can be 
 secured. It is usual to class the different methods of securing 
 ventilation under two general heads : they are, the natural and the 
 artificial. Now, all the methods of spontaneous diffusion produced 
 by the unequal density of two columns of air, whether caused by 
 chimney draughts or otherwise, belong to the former class ; while 
 the various methods of ventilation by means of pumps, fans, 
 bellows, and various other contrivances, belong to the latter. 
 The principles which bring about both these methods of ventila- 
 tion are not difficult to understand, being based upon the action 
 of well-known physical laws, all of which were discussed when we 
 considered the physical properties of air. 
 
 Natural Ventilation. — This is carried on by the simple 
 agency of gaseous diffusion, winds, and the movements of air 
 caused by inequalities of temperature. We have seen that every 
 gas diffuses at a rate which is inversely proportional to the square 
 root of its density, and that while two gases of the same density 
 show little tendency to mix, two other gases of different weights 
 or densities would intermingle with great rapidity. For this 
 reason, the air of rooms, being usually warmer than that outside, 
 diffuses with rapidity through cracks and openings, and even 
 through porous materials, such as sandstone, bricks, mortar, and 
 mud. To such an extent is this the case that experiments have 
 
32 
 
 AIR. 
 
 shown that with a brick-and-mortar wall, a room containing 2700 
 cubic feet of air has its entire contents changed in an hour when 
 the inside temperature is 65 ° F. and the outside just freezing. 
 The amount of interchange between the inside and outside airs 
 of rooms rapidly lessens, the more the temperature of the inside 
 and outside agree one with the other ; this explains why a room 
 is often better ventilated in winter during a frost, with all its 
 windows and doors shut and with a good fire in the grate, than in 
 summer, with the windows wide open, and the inside and outside 
 temperatures nearly identical. As a ventilating power, diffusion 
 alone is found to be inadequate. 
 
 The action ot winds, as an agent in the production of natural 
 ventilation, is partly by what is called perflation, and partly by 
 aspiration. The wind is said to perflate if it pass freely through 
 open doors and windows into a room ; its ventilating action then 
 is immense, but much less so if a thorough current cannot be 
 obtained, as in narrow courts and alleys, or when pieces of 
 furniture, curtains, etc., block the way. Mention has already been 
 made of the ease with which air can pass through bricks, etc., but 
 the action of the wind in this respect is probably not so powerful 
 as generally believed. The ventilating power of winds by mere 
 perflation is irregular, owing to the uncertainty of the air move- 
 ments. 
 
 As illustrating the great aspirating power of the winds, as a 
 ventilating agent, we may refer to the fact that winds blowing 
 
 over the tops of chimneys or tubes cause 
 a current of air to flow at right angles to 
 themselves up the chimney or tube (Fig. 
 3) ; at the same time a similar wind can 
 and does impede ventilation by either 
 blowing against some opening or down 
 a chimney. This reverse action can, of 
 course, be obviated by placing a cowl or 
 other similar contrivance on the top of 
 the chimney. Many schemes of ventila- 
 Fig. 3.— Draught up the chim- tion fail owinsr to their havinsr been de- 
 
 ney caused by the wind blow- • -, ... °. ,•,,, j . ,i„ 
 
 ing over the top. signed with too little regard to the 
 
 diversities of wind force and direction. 
 The primary force, which produces not only winds but the 
 movement of all bodies of air, is the difference in their weights or 
 densities due to inequalities of temperature. If a column of air 
 contained in a tube or chimney be heated, it expands, and the 
 movements of this expanded air depend upon the following con- 
 siderations : (1) Upon the difference between the temperature of 
 the inside and outside airs. (2) Upon the area and other condi- 
 
 > Wind 
 
NATURAL VENTILATION. 33 
 
 tions of the openings through which warmed air can flow out and 
 the cooler air flow in. (3) Upon the height of the ascending 
 column of warm air. 
 
 If a column of air, say in a chimney, be 10 feet high, and 
 have its temperature raised by a fire in the grate below, 20 F. 
 above that of the air outside the chimney, then it will expand, 
 for reasons already explained, -—j, or as near as possible —^ of 
 its bulk; as a result its specific gravity or density would be 
 lessened, and it would require to be io~ feet or 10 feet 5 inches 
 high to balance a column of the outer air 10 feet high when the 
 temperature of the latter is 20 F. lower than the former ; but as 
 the height of the warmer column is exactly that of its containing 
 chimney, which is only 10 feet high, the colder or outer column 
 of air presses it up with a force proportionate to their difference 
 in weight, and with a velocity equal to that which would be 
 acquired by a body falling through a space equal to the difference 
 in height that the two columns would occupy, if of equal weight, 
 which in this case is 5 inches or 0*4 foot. 
 
 Now, by an application of the combined laws of gravity and 
 the acceleration of forces, we are able to express the velocity in 
 
 feet per second of a falling body by the formula V = V 2 ^» m 
 which g is the velocity given to a falling body by the accelerative 
 force of the earth's gravity; this, in our latitude, is 32*2 feet per 
 second; h is the height through which the body falls. This 
 formula, V = /J 2g/i, which is sometimes called Montgolfier's 
 formula, will then stand or read, V= v/2 X 32*2 X^; but that 
 portion of the formula V 2 x 32*2 equals 8*02, or practically 8. 
 Hence, we can simplify it and write V = 2>*J h, or say the velocity 
 of the falling body equals eight times the square root of the height 
 it falls. In the case we have supposed, 0*4 foot is the height of 
 the effective descent or fall of the heavy column of colder air • 
 hence, applying Montgolfier's formula, we can say 8^/0*4 = 5*056 
 feet per second, or 303 feet per minute, will be the velocity 
 with which the heated column of air would be drawn up the 
 chimney. Very often in its application to ventilation problems 
 the whole calculation is expressed by the formula being written 
 thus — 
 
 V = J 2ga(t - t)h, 
 
 in which the other symbols remaining as above, a is the co- 
 efficient of the expansion of air for each degree of temperature, 
 / the temperature of the heated column of air, and / that of the 
 colder. 
 
 Having ascertained the exact velocity of the air-current, this, 
 multiplied by the area of inlet, gives the cubical amount entering 
 
 c 
 
34 AIR - 
 
 the space. Supposing, in the above example, the opening or throat 
 of the chimney were one foot square, there would pass out or 
 up that chimney 303 cubic feet per minute. This rate of flow is, 
 however, subject to certain corrections, chiefly in consequence of 
 friction arising from angular deviations of the chimney or tube. 
 In straight tubes, the friction is found to be in all cases directly 
 as the length of the tube and inversely as the diameter. In 
 general practice, a deduction of from one-fourth to one-third of 
 the velocity is necessary to compensate for these influences, and 
 to obtain a true rate of outflow. 
 
 There are various other ways of determining the direction and 
 velocities of air-currents. Thus, by noting the direction of smoke 
 caused by burning pieces of velvet ; by floating hydrogen balloons 
 so weighted as to be of the same specific gravity as the air ; or, 
 if such be available, by means of an anemometer. This latter 
 is a very delicate instrument, consisting of four vanes attached 
 to a spindle, the revolutions of which are recorded on a dial. If 
 placed in an air-opening about § of the diameter from the side, 
 so as to obtain the mean velocity, the vanes are turned by the 
 direct action of the air-current, and the velocity calculated from 
 the linear movement as recorded on the dial-plate during some 
 given period of time ; this, multiplied by the sectional area of the 
 opening, gives the cubical delivery or discharge according as to 
 whether it be an inlet or an outlet. The actual velocity of air as 
 it flows in and out of a room should not exceed one or at most 
 two feet per second, simply because a low velocity is favourable to 
 uniform diffusion of any incoming air through the room, and 
 because a high velocity is apt to give the sensation of a draught. 
 As explained, some allowance must be made for friction, par- 
 ticularly in outlets, and here the velocity should not exceed 3 to 
 5 feet per second. The particular velocity in any given case will 
 naturally be regulated by the sizes given to the inlets and outlets, 
 and on the quantity of air needed as indicated by the precise 
 number of occupants, the amount of artificial lighting, and other 
 special causes of air vitiation. 
 
 Having in the preceding pages learnedl something of the 
 general laws and circumstances which govern the movements of 
 air, as well as considered the amount of air to be provided, it is 
 necessary now to discuss the various methods which have been 
 adopted or proposed to practically apply them. Of all the 
 methods of natural ventilation, the simplest and most obvious is 
 that of more or less open doors and windows ; but this arrange- 
 ment, except in the warmest summer weather, causes draughts, 
 and is unpleasant. To secure adequate perflation, all windows 
 should, if possible, be placed on opposite sides of a room, while, 
 
NATURAL VENTILATION. 35 
 
 too, each of such windows should be made to open at the top. 
 Owing to air flowing against the body, at or even slightly above 
 the. temperature of a room, causing a sensation of cold or draught, 
 it is necessary for comfort that air should be introduced and 
 removed from inhabited rooms at those parts where it will not 
 give rise to a sensible draught. In a large majority of houses, 
 particularly those of the poorer and middle classes, even in these 
 days, ventilation arrangements are either of the most crude and 
 haphazard kind, or else absolutely wanting altogether. The 
 greater number of living-rooms depend for their supply of fresh 
 air upon just so much as can find its way in through doors, 
 windows, or through cracks and crevices around and under doors 
 and windows, or even through the floor, and for the escape of foul 
 air, upon what goes up the chimney, if a fire be alight, or what can 
 get out through doors and windows ; the general result being 
 that either the chamber is so cold and draughty that no one can 
 live comfortably in it, or so hot, close, and stuffy, that health is 
 affected. 
 
 All ventilation methods aim at avoiding these results, by 
 providing, in the first place, inlets, or means of entrance for the 
 fresh air, and outlets, or means of escape for the foul or impure 
 air. It will be readily understood that all inlets or orifices by 
 which cold fresh air is admitted should be above the level of the 
 heads of those occupying a room, say 9 feet, and directed 
 upwards to the ceiling, while the actual current itself should be 
 as much broken up or dispersed as possible by means of trumpet- 
 shaped openings, the smaller apertures of which are towards the 
 outer air and the wider towards the room. If the inlets be 
 intended for delivering previously warmed air, then they should 
 discharge near the floor. The warming of air previous to its 
 entering a room by an inlet is conveniently done, either by 
 the use of an air-chamber placed behind a grate or stove, as 
 in Galton's stove, or by the passage of it over hot-water pipes. 
 
 As to outlets, since the escaping impure air is invariably warmer 
 than the incoming or fresh supply, the right place for them is 
 the top of the room, and in cases where the foul air is specially 
 warmed, as over ventilating gaslights, the connection of the 
 outlet tube with the chimney constitutes the best arrangement. 
 In all cases, these structural devices, whether as inlets or outlets, 
 should permit of their being kept free from dirt or otherwise getting 
 blocked up. 
 
 Among the many devices for inlets of fresh air is the simple 
 plan, suggested by Hinckes Bird, of raising the lower sash of a 
 window by an accurately fitting block of wood, whereby a corre- 
 sponding space is left between the meeting-rails in the middle of 
 
36 
 
 AIR. 
 
 the window, through which entering currents of fresh air are 
 directed up towards the ceiling (Fig. 4). With the same idea, 
 others have proposed double panes of glass, an open space being 
 left at the bottom of the outer and at the top of the inner one. 
 Similarly, a pane may be louvred, that is, strips of glass lying one 
 over the other, and fixed on to a frame, which, by means of a 
 
 Fig. 4.— Hinckes Bird's plan of window 
 ventilation. 
 
 Fig. 5. — Louvre ventilator. 
 
 lever, can be opened or shut at will (Fig. 5). Windows can be 
 so made that, when they open, they slope into the room, or they 
 can have a part of a pane to open or shut by a spring, as in Boyle's 
 or Cooper's ventilator (Fig. 6). 
 
 An excellent form of inlet is that known as Sherringham's 
 
 Fig. 6. — Cooper's 
 ventilator. 
 
 Fig. 7. — Sherringham valve. 
 
 valve (Fig. 7), which consists of an iron box so made that the air 
 enters from outside through a perforated brick or grating, and is 
 directed up towards the ceiling by means of a valve which can be 
 made to close or open by means of a balanced weight. The 
 inside area of the ventilator is larger than the outer, consequently 
 
NATURAL VENTILATION. 
 
 37 
 
 the air enters the room at a less velocity than at which it passed 
 through the outer wall or grating. Another plan, advocated 
 originally by Tobin of Leeds, is that of introducing the air 
 through horizontal shafts under the floor, and then delivering it 
 into the room through vertical tubes (Fig. 8), at different heights, 
 varying from 6 to 9 feet from the floor. The currents of air 
 issuing from these tubes ascend and then curve imperceptibly 
 downwards. For public buildings, like churches or halls, the 
 columns which support galleries may on this principle form 
 convenient inlet tubes. These 
 Tobin tubes are not very suitable 
 for ordinary houses and dwelling- 
 rooms, as they are difficult to keep 
 clean, and often become clogged up 
 by cobwebs, dirt, and dust. They, 
 moreover, do not readily become 
 or act as outlets when occasion 
 requires, which, being a conspicuous 
 feature of the Sherringham valve, 
 renders that form of ventilating 
 agent practically the most convenient 
 for everyday application. 
 
 Suitable inlets can be provided 
 by what are known as air-bricks, of 
 which probably the best types are 
 those of Ellison and of Jennings. 
 They are merely specially prepared 
 bricks perforated with a number of holes, so cut that the inner 
 aspects of the perforations have a larger diameter than the outer, 
 whereby the velocity of the entering air-current is lessened. 
 The wind blows through them, but with a variable movement. 
 In Jennings' air-brick, the perforations are directed upwards, 
 so that the entering air-current flows rather towards the ceiling 
 than down towards the floor. 
 
 With all or any of these simple ways of letting fresh air into 
 rooms, it is presumed that equal facilities are offered for the escape 
 of the foul air. In most rooms, particularly if a fire be alight, 
 this will be done largely by means of the chimney connected 
 with it, but in its absence may need be accomplished by special 
 outlets. The simplest form of outlet, other than a chimney, is a 
 special shaft from the ceiling to above the roof; this is the 
 principle adopted in the army for ventilating barrack-rooms and 
 hospitals, combined with arrangements for admitting warmed air. 
 The movement of air up such an outlet shaft will largely depend 
 upon the aspirating action of the wind over its top, and upon the 
 
 Fig. 8. — Tobin's ventilating system. 
 
38 
 
 AIR. 
 
 particular temperature inside it as compared with that of the 
 outer air. Owing to the uncertain and disturbing action of these 
 influences, these shafts do not always act as outlets, but in any 
 case facilitate a continuous change of air, whichever way they 
 happen to act. Down currents in such shafts can usually be 
 obviated by placing a cowl or valve on its upper orifice, or by 
 leading it up inside a chimney. 
 
 Frequently so-called ventilating gaslights are used as outlets, 
 in which the products of combustion, after being collected by 
 means of a cover or bell-glass, are carried off by a tube which is 
 itself often contained in a larger one. Owing to the heating of 
 the inner tube, the space surrounding it and between it and the 
 outer one acts as an extracting-shaft for foul air. In theatres and 
 other public buildings, advantage is taken of this method by 
 using the Sunlight gas-burners, which, in addition to lighting the 
 building, act as extraction-shafts for removing the polluted air. 
 
 Another arrangement, known as Arnott's valve (Fig. 9), is 
 designed to act as an outlet for foul air. It is usually placed in 
 the wall of a room near the ceiling, so as to open into the chimney. 
 The valve is so arranged as to swing towards the chimney, when 
 the pressure or draught of the air is from the room to the 
 chimney; but when the pressure is greater from the chimney to 
 
 the room the valve closes, 
 and thus prevents the escape 
 of smoke or air from the 
 chimney into the room. These 
 valves are sometimes objec- 
 tionable owing to the noise 
 they make. 
 
 An ingenious ventilator is 
 
 that of McKinnell's, which 
 
 consists of two tubes, one 
 
 up through the ceiling of a room ; 
 
 in between the two tubes, and by a 
 
 is dispersed. The inner, or outlet 
 
 Fig. 9. — Arnott's valve. 
 
 inside the other, carried 
 fresh air passes down 
 flange on the inner tube 
 
 tube, which is always made sufficiently large to equal in area 
 the inlet, projects well beyond the other, both above and below, 
 and effectively carries off foul or impure air. This is a very 
 useful method of ventilation under certain conditions, but, like 
 all others, is not universally applicable. On much the same 
 principle, ventilating cornices are made, which consist of a 
 double channel of perforated metal : by the lower channel cold 
 fresh air is brought into a room, while by the upper one the 
 fouled air is carried to the chimney or other outlet. Analogous 
 to this plan is that of carrying along the cornice of a room, on 
 
NATURAL VENTILATION. 39 
 
 three sides, a perforated inlet tube, while on the fourth side is a 
 similarly perforated outlet tube. 
 
 In other cases, by a like contrivance a fairly good cross- 
 ventilation can be secured by means of a series of transverse 
 ventilating boxes or tubes placed at regular intervals and close 
 to the ceiling. These, running across the room from wall to 
 wall, open into the outer air at each end by an air-brick. The 
 sides of these tubes are made of perforated zinc, and to prevent 
 the wind blowing right through, they are stopped or blocked 
 in the centre by a partition. According as to whether the wind 
 blows from one side or other, so one half becomes an inlet for 
 fresh air, which diffuses gently into the room through the 
 perforations, while the other half acts as an outlet for the fouled 
 air. 
 
 As regards the size of inlets and outlets, the conditions of 
 temperature are so variable that it would be impossible to fix on 
 a size that should be universally applicable ; as an average for this 
 country a size of 24 square inches per head for inlet, and the 
 same for outlet, seems calculated to meet common conditions ; 
 but arrangements should be made for enabling this to be lessened 
 or closed in very cold weather, or if the influence of strong winds 
 is too much felt. As a rule, the size of these openings should be 
 in proportion to the size of the room ; it is better to have openings 
 too small than too large, and while the inlets and outlets can be 
 usually of the same size, still no one individual inlet ought to 
 be larger in area than 60 square inches, nor an outlet more than 
 144 square inches. 
 
 Artificial Ventilation. — For the production of artificial venti- 
 lation, two systems are in use : namely, ventilation by extraction 
 and ventilation by propulsion. 
 
 The simplest example of ventilation by extraction is the 
 action of an ordinary fireplace, which, by heating a column of 
 air, causes its expansion, ascent, and replacement by another but 
 colder volume. The ventilation of theatres is largely carried out 
 by utilizing the central chandelier and all the gas-jets, which 
 being each placed under outlet tubes, by warming the vitiated 
 air, cause it to expand and escape up the tubes, which are so 
 arranged as to all unite and empty themselves into a single large 
 outlet, thus serving to carry off the products of both respiration 
 and combustion. Mines are largely ventilated by means of a 
 furnace at the foot of the upcast shaft, its supply of air being 
 drawn down another shaft and then made to pass through all the 
 workings on its way to the upcast by an ingenious arrangement 
 of doors and partitions. 
 
 As typical of an elaborate means for ventilating artificially a 
 
4-0 
 
 AIR. 
 
 large building may be mentioned the system employed in the 
 House of Commons. The system is a plenum one, coupled with 
 exhaust, a condition of working being that the inflow of air is 
 slightly in excess of that extracted. There are three air 
 intakes at the basement. At the initial point of entry the 
 air passes over heat radiators; these are for use during cold 
 weather. The air is drawn through wire screens, 20 meshes 
 to the linear inch, in front of which are water sprays. The 
 effect of this screen is to remove 60 per cent, of the suspended 
 bacteria, increase the humidity, wash out any fog, and give a 
 
 gl l >. :}.",".: - A > M >"."\ "\>M>A\WM>Ah 
 
 Q 
 
 U 
 
 S3- 
 
 i 
 
 -> a 
 
 Fig. 10 — Diagram of ventilating the Houses of Parliament. 
 
 definite cooling effect. The air supply then passes along a glazed 
 duct to the input fan, running at from too to 190 revolutions per 
 minute, and giving in that time from 20 to 60 thousand cubic feet 
 of air. Between the fan and water screen are special chambers or 
 air locks to prevent side leakage of undesirable air from the base- 
 ment corridors. From the fan the air passes along another duct 
 to a heating chamber, fitted with radiators. In time of fog, the 
 direct connection between the fan and the heating chamber is 
 closed and the air diverted so as to pass through a huge cotton- 
 wool screen which acts as a filter and removes the suspended 
 
ARTIFICIAL VENTILATION. 41 
 
 material of which a fog consists. In fog time, after being so 
 filtered, the air passes to the heating chamber. Between this 
 heating chamber and the debating chamber is an equalizing 
 chamber where the air is made equable in velocity and tem- 
 perature. 
 
 The control of the whole system is from this point. From 
 the equalizing chamber the air enters the debating chamber by the 
 perforated gangway floors and by apertures beneath the benches. 
 The vitiated air is extracted from the debating chamber through 
 apertures in the wall panels by means of an outflow fan, similar to 
 the input fan. The extracted air is discharged into a vertical shaft 
 fitted with a furnace. The outflow fan is connected also by 
 ducts and shutter valves with the lobbies, and can, if necessary, 
 extract wholly from these places. This is a flexible arrangement 
 whereby the whole system can be varied according to where the 
 members of the House happen to be. In addition, there are 64 
 sun gas-burners in the debating chamber, the draught from them 
 being sufficient to renew the contents of the chamber once an 
 hour. The ventilation of the gallery is on the same principle, 
 controlled by a separate series of ducts and a separate outflow fan. 
 
 In dwelling houses it has been proposed to have a central 
 chimney, into which the flues of all the fires shall open, and to 
 surround this with air-shafts from each room. It is supposed that, 
 if other inlets exist, there will be a current both up the chimney 
 and up the shaft running beside it. In all these cases it is 
 necessary that the workmanship be very exact, so that air shall 
 not reach the extracting shaft except through the tubes. 
 
 On board steamships, a similar plan is arranged, the upcast 
 being a space round the boilers and funnel ; and while a strong 
 current of air rushes up this space, air to feed it is directed down 
 the hatchways. The same method is turned to account in hotels 
 and public buildings by the utilization of hot-water pipes to cause 
 currents of air in suitable extraction-shafts. 
 
 As aids to extraction methods, various forms of cowls have 
 been invented, but no one of them can be recommended as being 
 absolutely successful. More successful is extraction by fans. A 
 paddle-wheel-shaped fan, inclosed in a chamber, is placed in the 
 roof of a building and conveniently driven by a small engine. By 
 the revolutions of the fan, the foul air is drawn up from the 
 apartments through ventilators placed near the ceiling into tubes, 
 and by them conducted to an open-air outlet above the fan. 
 Fresh-air inlets are of course provided near the floor levels of the 
 room so ventilnted. 
 
 In the case of ventilation by propulsion, the air is driven 
 mechanically by either bellows, pumps, or fans into proper 
 
42 AIR. 
 
 channels. This plan of artificial ventilation is more adapted for 
 factories and workshops than for ordinary houses. In the former, 
 besides for ordinary ventilation, currents of air are often required 
 to blow away dust or suspended matters, for which purpose the 
 openings need to be near the floor and not near the ceilings, as 
 for ordinary vitiated air. Strictly speaking, what is called the 
 propulsion method is an impulsion system, as by it fans are used 
 to propel air into a basement chamber, from whence, after being 
 heated over coils of hot-water pipes, it is carried by ducts to each 
 room separately. These ducts open some 7 feet above the floor 
 level, and as the velocity of the impelled air is considerable, it is 
 diffused near the ceiling, and moves down through the room im- 
 perceptibly, to finally escape at the floor into vertical outlet shafts 
 discharging at the roof. 
 
 Though much less common than extraction methods, venti- 
 lation by propulsion has the advantage of precision and ease and 
 certainty with which any given volume or required volume of air 
 can be treated or used ; it, however, is expensive. Owing to the 
 absence of control over the sources from which air is sucked in 
 extraction methods, due to the readiness with which air rushes in 
 at all available apertures, the supplies of air under these circum- 
 stances are occasionally drawn from objectionable places. With 
 care, however, provision can be made to either warm, cool, wash, 
 or filter the air at suitable points. 
 
 On the whole, the advantages of artificial ventilation are great, 
 being mainly due to its facility of management and constancy 
 under varying conditions. For factories, workshops, ships, and 
 wherever there is machinery, artificial ventilation, whether by 
 extraction or propulsion, is certainly the most economical and 
 convenient. On the other hand, public buildings, such as prisons, 
 theatres, and hotels, commonly require to be ventilated by some 
 mechanical arrangement based upon the utilization of all fires 
 and gas to work an exhaust-shaft. In private houses, the use of 
 ventilating grates and stoves, or some of the simpler plans of 
 ventilation, should suffice to keep the air pure, but no hard-and- 
 fast rule can be laid down, each case requiring to be considered 
 intelligently on its merits. 
 
 Warming and Heating. 
 
 This subject is very closely connected with ventilation, but for 
 its thorough comprehension some knowledge is necessary of the 
 laws of heat. Now, heat is distributed in three ways : these are 
 by radiation, by conduction, and by convection. 
 
 Radiation of heat is not only the most common but the most 
 
WARMING AND HEATING. 43 
 
 wasteful. This kind of heat is propagated in straight lines in all 
 directions with equal intensity, the effect lessening according to 
 the square of the distance ; thus, if the heat at one foot distance 
 from a fire be i, then at ten feet it will be one hundred times 
 less. If radiant heat fall on a solid body, it is reflected in the 
 same way as light, but some of the heat is absorbed, the amount 
 reflected and absorbed being in inverse proportion to one another, 
 and largely dependent upon the surface, colour, and nature of the 
 body. 
 
 Heat is conducted through all solids, but to a very limited 
 degree only by liquids and gases. The best heat conductors are 
 the metals, then stone, next wood, and least of all wool or silk. 
 Bodies which are good conductors rapidly give off their heat to 
 the surrounding air or to anything in contact with them ; in like 
 manner, if colder, they withdraw heat from other bodies. Porous 
 materials, like felt, are extremely bad conductors of heat. 
 
 The convection of heat is that mode in which heat is propa- 
 gated in liquids and gases, and is dependent upon that character- 
 istic of those bodies which allows the portions of them which 
 have been heated to expand and rise, their place being taken at 
 once by colder parts. A sort of circulation of the water or air is 
 set up, and the whole mass soon warmed. 
 
 Disregarding any particular variations in the source of heat, 
 that is, whether from coal, coke, wood, etc., we can say that the 
 principal methods of warming and heating houses or rooms may 
 be classed as either open fires, closed fires or stoves, and pipes 
 containing either heated air, hot water, or steam. 
 
 Open Fires. — Long-established custom and prejudice have 
 caused open fires to be the means of heating nine-tenths of the 
 houses in England, notwithstanding the fact that they are really 
 the most costly and imperfect means of heating, as evidenced by 
 the fact that they only render available 13 per cent, of the total 
 heat capable of being yielded by coal or coke, and only 6 per 
 cent, of that by wood, the rest being lost in the air, or escaping 
 as unconsumed carbon up the chimney. The actual heating 
 effect of open grates is most unequal in different parts of a room, 
 but on account of the cheerful light which they emit, and the 
 ventilation which they ensure, open fires will always be preferred 
 as the pleasantest and healthiest mode of heating. Following 
 Teale, the chief practical points to be aimed at in making open 
 fireplaces, may be summarized as follows : — (1) Use as little iron, 
 but as much fire-brick, as possible. (2) The back and sides 
 should be made of fire-brick. (3) The back of the fireplace 
 should lean or hang over the fire, while the throat of the 
 chimney should be contracted. (4) The bottom of the fire 
 
44 AIR - 
 
 should be deep, and placed low down near the floor. (5) All 
 slits in the bottom of the fire should be as narrow as possible. 
 (6) The bars in front should be narrow. (7) The space beneath 
 the fire should be closed in front by a close-fitting iron shield or 
 " economizer." The object of this latter point is to secure as 
 complete combustion as possible of the fuel at the bottom of the 
 fire by the exclusion of cold air. In the use of an ordinary open 
 fireplace, about one-eighth of the heat given off by the fuel 
 consumed is utilized on the air of the room. All open grates 
 should be made so as to have the fuel slowly and completely 
 consumed, while the draught up the chimney should not be in 
 excess of ventilation requirements. Most English grates con- 
 sume 8 lbs. of coal in an hour : for the combustion of each 
 pound of coal 300 cubic feet of air are needed ; .this means 
 2400 cubic feet hourly, but in actual practice something like 
 20,000, or even 40,000, cubic feet of air pass up the chimney ; in 
 which case,- supposing the room contains 4000 cubic feet of 
 space, the air in it gets changed from 5 to 10 times in the hour 
 according to the strength of the fire. If the incoming air were 
 warm, this liberal ventilation would be excellent ; but, unfortu- 
 nately, it rarely is so, but is in the main quite cold, finding 
 entrance through the floor, or by chinks round the windows or 
 beneath the door. 
 
 Stoves, as usually made, are of cast iron, and are essentially 
 apparatus for heating with a detached fire, so placed that the 
 products of combustion escape by an iron flue or chimney to the 
 outer air, while the main portion of the generated heat radiates in 
 all directions round the stove. At the lower part is usually a 
 draught-hole, by which the air necessary for combustion enters. 
 Owing to the less waste of heat by these means of warming than 
 by open grates, this mode of heating is the more economical, but 
 by no means so healthy as that by ordinary fireplaces, because 
 their ventilating power is so much less. Stoves are often objec- 
 tionable owing to their making the air hot and dry, but this can 
 be obviated usually by placing vessels of water upon them. They 
 often, too, emit a bad smell, due generally to the decomposition 
 of organic matter present in the air, by contact with the heated 
 sides of the stove and chimneys, or occasionally from the 
 diffusion of carbon monoxide and other gases through the 
 heated sides of the stove. These objections can in great measure 
 be obviated by the use of wrought iron, and having the joints 
 more securely riveted than is commonly the case ; or the stoves 
 may be lined with fire-brick and covered with tiles, as is seen in 
 the better class of houses on the Continent. 
 
 Gas, of later years, has come into very general use both for 
 
WARMING AND HEATING. 45 
 
 warming and cooking ; it is admirably adapted for the latter, 
 being not only cleanly but economical. For heating purposes, 
 it has not made the progress which its many advantages deserve, 
 probably owing to defective forms of stove used. Speaking 
 generally, there may be said to be three common forms of gas- 
 stove in general use : there are (i) reflector stoves, (2) con- 
 densing stoves, (3) asbestos or hollow-ball refractory fuel stoves. 
 
 The Reflector stove has usually a naked gas-flame, backed by 
 a glass or metal reflector. It is bright and cheerful-looking, but 
 gives out little heat, and unless provided with a flue — which more 
 often than not is not provided — very considerably adds to the 
 vitiation of the air. 
 
 Condensing stpves are those so constructed that the water 
 vapour, which is one of the products of gas combustion, is con- 
 densed by passing through upright tubes, and then caught in a 
 tray beneath. This condensed vapour naturally carries down 
 with it some if not all the sulphur products, but fails to remove 
 any of the carbon dioxide which, notwithstanding all statements to 
 the contrary, really escapes into the room. For this reason, this 
 stove always requires a flue ; unfortunately, its heating powers are 
 small. 
 
 Stoves fitted with asbestos fibre or refractory hollow-ball fuel, 
 and lighted by Bunsen or Argand burners, are relatively popular, 
 owing to the fact that the fuel is rendered incandescent, with a 
 close resemblance to the glow of an ordinary coal fire. These 
 stoves yield radiant heat only as a rule, though a few are made 
 with attached hot-air chambers, to give off heated currents of air. 
 These are in the main good stoves, but somewhat extravagant as 
 gas consumers, and always needing a flue to carry off products of 
 combustion, and which as well takes off much of the heat which 
 they produce as so much waste. 
 
 A notable improvement upon the various types of gas stove is 
 the gas radiator, in which the intense heat from a Kern flame is 
 translated into radiant heat by surrounding it with a perforated 
 fire-clay tube. The whole radiator consists of a number of these 
 tubes placed over Kern burners, each consuming two cubic feet 
 of gas per hour. The Kern burner is a modified Bunsen. Ex- 
 periments made with radiators of this type show that they give 
 a cheerful, healthy, radiant heat combined with economical con- 
 sumption of gas, and little or no deterioration of the air. Possibly, 
 as electricity comes into more general use, a more extended 
 employment of electric radiators for heating purposes will be a 
 feature of many houses. On sanitary grounds, electric radiators 
 are much to be recommended, as they emit heat without adding 
 to the atmosphere any of the ordinary products of combustion. 
 
46 
 
 AIR. 
 
 Oil Stoves. — Under some circumstances the use of oil stoves 
 affords a convenient means of heating rooms. Provided that the 
 combustion of the oil is complete, and that the ventilation is 
 sufficient for the ordinary effects of respiration, the use of oil 
 stoves for heating purposes may be advantageously employed. 
 Their efficiency is increased by placing over them a diffuser or 
 
 radiator, so as to distribute 
 the heated products ; care 
 needs also to be taken that 
 only the better kinds of 
 mineral oil are used. 
 
 Hot Air, obtained by 
 driving air over hot bricks or 
 pipes, is occasionally intro- 
 duced into rooms and public 
 buildings for heating purposes, 
 by means of mechanical ar- 
 rangements such as fans, as 
 used in artificial ventilation 
 methods. This is very efficient 
 as a way of combining warm- 
 ing with ventilation, but is 
 very costly. A modified ap- 
 plication of this method was 
 designed by Sir Douglas 
 Galton in the form of a stove, 
 in which the fire which warms 
 the room is also utilized to 
 supply warm air. The figure 
 shows the existence of an air- 
 chamber behind the grate, in 
 which the air is warmed by 
 the iron back, upon which 
 several broad iron flanges are 
 cast so as to obtain a large 
 surface of metal to give off 
 Fig. ii.— Elevation of Sir Douglas Gaiton's heat. The fresh air is ob- 
 
 duc?kndflue S C . ti0n ° f r °° m ' Sh °* ing ^ talned b y meanS ° f an inlet 
 
 flue from the outside, and, 
 after being warmed, is passed into the room near the ceiling by 
 the opening shown in the illustration. These stoves are in use 
 in the British army for warming and ventilating barrack-rooms 
 and hospital wards. 
 
 The chief objection to the use of hot air as a general means 
 of warming a room or dwelling lies in the fact that heated air 
 
 m — *- 
 
WARMING AND HEATING. 47 
 
 is often unpleasantly dry, and when so employed should be 
 moistened, or, if need be, purified by either filtration or 
 washing. 
 
 Steam or Hot Water is closely allied to hot air for warming 
 purposes. The ease with which all parts of a building can be 
 heated by pipes containing steam or hot water is obvious, and, 
 as applied to the needs of hotels, hospitals, churches, etc., is 
 practically supplanting all other methods of warming. In the 
 present day, steam is very little used for this purpose, since water, 
 at either high or low pressure, is so much more convenient and 
 cheaper. In low-pressure water systems the pipes are about 4 
 inches in diameter, and are always in a double row to allow 
 of the water circulating. The boiler in connection with it is 
 commonly placed in the basement of the building, and from its 
 upper part runs a main pipe, ending in branches, which extend 
 to the furthest end of the building ; these then return underneath 
 the others, unite into another single pipe, and then re-enter the 
 boiler at its bottom. The circulation of the water is dependent 
 upon the water, after being heated, being lighter than when cold, 
 and as such tending to rise to a higher level ; this having given 
 up its heat to the various rooms, returns cooled by the lower 
 pipe. 1 The heat of the pipes is controlled by a valve which can 
 be opened and closed at will. A feed-pipe from a supply cistern 
 enters the return pipe near the boiler, while an escape for air is 
 provided at the highest point of the system. In the high-pressure 
 system, such as Perkins's, water is heated to about 300 F., in a 
 portion of the pipes which pass through the furnace. This 
 system secures .a greater heat, but requires very careful manage- 
 ment, as any failure in the circulation would at once result in 
 an explosion. Under the low-pressure system, 5 feet of a 4-inch 
 pipe will warm 1000 cubic feet of air from 32 F. to 55 , and 12 
 feet will warm the same to 65°; but under the high-pressure, in 
 which the heating power is something like two-thirds more, a 
 proportionately less length of piping is required. 
 
 For calculating the necessary radiation for any given house or 
 building, the construction of such building must be considered 
 as to the kind of outside walls, their thickness and material. So, 
 too, the height of rooms will make a difference, while the ventila- 
 tion must be also taken into consideration, and provision made 
 to renew the air at least once an hour. The following general 
 rules are given by Lawler : — 
 
 1. Allow 1 square foot of direct steam radiation for each 
 3 square feet of glass. 
 
 2. Allow 1 square foot of direct steam radiation for each 30 
 square feet of exposed or outer wall. 
 
48 AIR. 
 
 3. Allow 1 square foot of direct steam radiation for each 100 
 feet of space or contents of room. 
 
 It requires more radiating surface for hot-water heating than 
 is necessary with steam, for the reason that the average tempe- 
 rature carried in a hot-water system is much lower than in a steam 
 system. In round numbers, it requires about 25 per cent, more 
 radiation surface for hot water than for steam. Lawler gives the 
 following general rules : — 
 
 1. Allow 1 square foot of direct hot-water radiation to 2 square 
 feet of glass. 
 
 2. Allow 1 square foot of direct hot-water radiation to 25 
 square feet of exposed wall. 
 
 3. Allow 1 square foot of direct hot-water radiation for each 
 75 cubic feet of air-space. 
 
 The Practical Examination of Air and Ventilation. 
 
 It has already been pointed out that the simplest test as to 
 whether the ventilation of a room or a house is sufficient or not, 
 is that of entering it from the external air, and noting the differ- 
 ence between the indoor air and the outside atmosphere in point 
 of freshness. This test, however, only gives approximate results, 
 and, in cases where more exactness is required, a more detailed 
 examination is necessary. This, in every case, may be con- 
 veniently made to include the following points : — 
 
 1. The actual amount of cubic space, the relative size and 
 position of inlets and outlets, and the amount of fresh air 
 supplied. 
 
 2. The chemical examination of the contained air for im- 
 purities. 
 
 3. The nature of the suspended impurities. 
 
 4. Facts concerning the temperature and moistness of the air. 
 The determination of the actual amount of cubic space is 
 
 merely a simple matter of measuring and calculation, combined 
 with the making of certain deductions for bedding, furniture, etc., 
 and irregularities in the shape of the space to be examined or 
 additions for the cubic contents of open recesses. For each 
 bedstead and bedding a general allowance of 10 cubic feet is 
 made, and for the body of each adult 3 cubic feet. If the room be 
 rectangular or regular in shape, its cubical contents will be obtained 
 by multiplying together the three dimensions of height, length, 
 and breadth; if the space be irregular in shape, with either 
 rectilinear or curved lines, it is usually most convenient to divide 
 it up into simple parts, such as either triangles or circles, as the 
 case may be, and calculate the cubical contents by one or more 
 
MEASUREMENT OF CUBIC SPACE. 
 
 49 
 
 of the following rules. It is generally more convenient, too, to 
 make the measurements in feet and decimals of a foot, than in 
 feet and inches. If square inches are used, they may be turned 
 into square feet by multiplying by 0007. 
 
 Area of a circle = square of the circumference X 0*0796 or 
 
 square of the diameter x 07854. 
 Circumference of a circle = diameter X 3'i4i6. 
 Diameter of a circle = circumference X o"3i83. 
 Area of an ellipse = the product of the long and short 
 
 diameters X 07854. 
 Area of a square = the square of one of the sides. 
 Area of a rectangle = the product of two adjacent sides. 
 Area of a triangle = altitude X \ base, or base X \ altitude. 
 Area of any figure bounded by straight lines = divide it into 
 
 triangles and take the sum of their areas. 
 Area of the segment of a circle = (§ X chord X height) 
 
 cube of altitude 
 
 + 
 
 solid triangle = area of a triangle 
 
 2 X chord 
 Cubic capacity of a 
 
 X altitude. 
 
 Cubic capacity of a cylinder = area of base X altitude. 
 Cubic capacity of a cone or pyramid = area of base X \ 
 
 altitude. 
 Cubic capacity of a dome = area of base x § altitude. 
 Cubic capacity of a sphere = cube of diameter x o # 5236. 
 
 Thus, supposing it were required to determine the cubic 
 capacity of a room 10 feet in height, and whose floor and ceiling 
 shape were as drawn 
 in Fig. 12, ABGCD. 
 By dividing it into 
 triangles and the seg- 
 ment of a circle, and 
 then measuring the 
 length of the various 
 dotted lines, its total 
 cubical capacity would 
 readily be obtained. A 
 Assuming AB to be 
 6 feet, BC to be 8 feet, 
 CD to be 6 feet, BD to be 10 feet, BE to be 7 feet, ED to be 
 3 feet, FD to be 9 feet, FA to be 4 feet, EC to be 4 feet, GH 
 to be 3 feet, and BF to be 5 feet, we get the cubical capacity of 
 each of the figures to be as follows : — 
 
 Fig. 12. 
 
50 AIR. 
 
 
 
 
 
 
 
 Cubic feet 
 
 ABF 
 
 • 
 
 • 
 
 . 4 x | X 10 
 
 
 
 = IOO 
 
 FBD 
 
 • 
 
 • 
 
 . 9 x I X io 
 
 
 
 = 225 
 
 EEC 
 
 • 
 
 • 
 
 . 7 x i x io 
 
 
 
 = I40 
 
 CED 
 
 • 
 
 • 
 
 . 3 x | x io 
 
 
 
 = 60 
 
 BGC 
 
 • 
 
 • - 
 
 . (§ x 8 x 3) + 
 
 27 
 
 2X8 
 
 X 
 
 IO = 177 
 
 This gives a total cubic capacity of . . 702 
 
 Having determined the total number of cubic feet, with all 
 deductions and additions, and dividing this sum by the number 
 of persons living in the room, the result is the cubic space per 
 head; whilst the total area of the floor-space divided by the 
 number of persons, gives the floor-space per head ; this we know 
 should be as near as possible ^ of tne cuoic s P ace - When this 
 has been done, the next thing is to count the various openings 
 in the room, and note the direction of movement of the air 
 through them. As a general rule, one-half of the openings will 
 be inlets and the other half outlets, but this is not always so ; 
 the actual condition of affairs will be best learnt by observing the 
 directions given to smoke disengaged by smouldering brown 
 paper, velvet, feathers, or even light balloons. The direction of 
 the air-currents ' being known, their rate of movement must be 
 determined either by an anemometer, if such be available, or by 
 calculation of the theoretical velocity as obtained by Montgolfier's 
 formula, allowance being made, of course, for friction. If the 
 ventilation is meant to be effectual when doors and windows are 
 shut, these should be closed during this examination. 
 
 It may be accepted as a good rule that the amount of air 
 issuing up a chimney or other large outlet is a far more reliable 
 index of the fresh air being supplied than the amount actually 
 ascertained to be entering through inlets ; in fact, the fresh air 
 supply can be rarely fairly estimated in any other way, as the air, 
 even in the best of built houses, enters through many chinks and 
 crevices, or even through porous walls themselves, in such a way 
 as to be beyond all absolute or accurate calculations. 
 
 Having, then, made these various preliminary inquiries, it may 
 be necessary to chemically examine the respired air itself, in which 
 case samples of the air must be taken at such times as will yield 
 fair evidence as to the efficiency or not of ventilation. Thus, in 
 the case of a bedroom, the sample yielded during daytime, with 
 no one in the room, would be no value as an index of the state of 
 the air during the night, when its usual occupants were sleeping 
 in it. Therefore all samples should be collected at an hour when 
 the greatest accumulation of impurities is likely to occur. For 
 
EXAMINATION OF AIR AND VENTILATION. 5 1 
 
 sleeping rooms this will usually be best secured at any hour 
 between midnight and 5 a.m. 
 
 For the collection of an air sample, the simplest method is to 
 obtain a glass jar or vessel, provided if possible with an india- 
 rubber cap or stopper, and capable of holding from half to one 
 gallon, and then accurately measure its capacity. If this be filled 
 with clean water, and, after emptying it in the room or air-space 
 it is desired to examine, the jar be then carefully closed with 
 either an indiarubber cap or stopper, the contents of the vessel 
 will be so much of the air required to be examined. Since the 
 amount of hurtful organic impurity in air increases or diminishes 
 with the quantity of carbon dioxide given off by persons inhabiting 
 any particular air-space, the estimation of this gas constitutes the 
 chief chemical examination required for ventilating purposes. 
 For its determination the following method, known as Petten- 
 kofer's, is at once the most simple and the most useful. 
 
 Estimation of Carbon Dioxide in Air. — Having filled a Win- 
 chester quart bottle, or other suitable vessel of known capacity, 
 with clean water, and emptied it in that part of the air-space it is 
 desired to examine, taking care to let it drain well, pour into it 
 60 c.c. of freshly prepared lime-water, and close it with an india- 
 rubber cap or stopper. Shake the air and the lime-water in the 
 bottle well up together, and allow to stand for half an hour or 
 so. During this time the carbon dioxide in the air within the 
 bottle will be absorbed by the lime-water, and its causticity or 
 alkalinity lessened. If the causticity of the lime-water be known 
 both before and after the experiment the amount of C0 2 can be 
 calculated that was present in the air of the jar. A solution of 
 crystallized oxalic acid is used to determine the causticity of this 
 lime. This is made by dissolving 2*84 grams of crystallized 
 oxalic acid and making the solution up to one litre with distilled 
 water. One cubic centimetre of this solution is equivalent to 
 o"5 c.c. of carbonic acid at standard temperature and pressure. 
 Take 30 c.c. of the original lime-water and by titration with the 
 oxalic acid solution determine the exact point of neutralization, 
 using either turmeric paper or phenolphthalein as the indicator. 
 Next determine the causticity or alkalinity of 30 c.c. of the lime- 
 water in the jar in precisely the same way by means of the oxalic 
 acid solution. Twice the difference between the two estimations 
 of alkalinity gives the amount lost by 60 c.c. of lime-water put 
 into the jar, and since each c.c. of oxalic acid solution is equivalent 
 to half a c.c. of carbon dioxide the amount of carbon dioxide in 
 the cubic centimetres in the jar, less 60, is readily determined. 
 
 Suppose, in a jar of a capacity of 4385 c.c, it is found that 
 30 c.c. of lime-water, after standing some while, lose alkalinity, 
 
52 ATR. 
 
 represented by 6 c.c. of the oxalic acid solution, equivalent to 
 3 c.c. of C0 2 , then for the 6o c.c. of lime-water put in the jar the 
 alkalinity lost is equal to 6 cubic centimetres of carbon dioxide. 
 The original capacity of the jar was 4385 c.c. and this less 60 c.c. 
 for the lime-water put in gives 4325 c.c. of air in which we have 
 found 6 c.c. of C0 2 or an amount equal to 1*38 c.c. of carbon 
 dioxide in 1000 c.c. of air. 
 
 If the air of the room be above or below 32 F., a correction 
 must be made by adding or deducting, as the case may be, 2 per 
 1000, or 0-002 for each volume. The reason of this correction 
 being required is because the ratio between weight and volume 
 of C0 2 as given above is only true for the precise temperature of 
 32 F., and consequently the volume of air must be corrected 
 for just so much as the heat of the air varies from that tempera- 
 ture. Suppose the temperature of the room, when the sample 
 of air was collected, had been 55 F., that is, 23 above the 
 standard of 32 , therefore 23 x 2 = 46 per 1000 of C0 2 must 
 be added to what has been shown above, simply because there 
 was that amount less of air in the jar at that particular temperature 
 than there would have been had the temperature at the time of 
 collection been at 32 ; the result of this correction means that 
 instead of 1 "38 parts of C0 2 per 1000 of air being present, the true 
 amount is 1*44 per 1000. 
 
 A further correction for barometric pressure may be made, if 
 the height of the place is much above sea-level, or if the barometei 
 read below the standard level of 29*92 inches ; the correction being 
 0*26 per cent, for each difference of ~ of a degree in pressure. 
 As a rule, however, this correction is very rarely required. 
 
 Estimation of Organic Impurities in Air — Besides the esti- 
 mation of carbon dioxide, the chemical examination of air, strictly 
 speaking, includes the determination of the organic matter and 
 the ammonia in it. To obtain a merely approximate idea of the 
 organic impurities, the air may be washed or drawn through a 
 very dilute solution of permanganate of potash, of a known 
 strength, and the result expressed as so many cubic feet of the 
 air which it takes to decolourize 1 mgm. of the permanganate. 
 The estimation of the ammonia in air is a still more delicate 
 process, and is performed by washing the air with ammonia free 
 water, and then estimating in the water the ammonia yielded by 
 the air ; the actual process is described in the following chapter 
 on water. As tests for the determination of various degrees of 
 respiratory impurity, both the estimation of the organic matter 
 capable of being oxidized by permanganate and of the ammonia 
 present, are quite subsidiary to that for determining the carbon 
 dioxide, and but rarely employed. 
 
EXAMINATION OF THE SUSPENDED MATTERS IN AIR. 53 
 
 Examination of the Suspended Matters in Air. — This will, 
 of course, be essentially microscopic. The suspended matters 
 contained in the air of any particular space or locality may be 
 conveniently collected by drawing the air through distilled water, 
 then, after allowing the suspended matters to subside, to examine 
 them under the microscope ; or the air may be drawn or sucked 
 into an exhausted receiver, through a fine aperture, so as to strike 
 upon a piece of glass moistened with glycerine, which, of course, 
 arrests the suspended matters. This is practically the plan of 
 Pouchet's aeroscope. 
 
 These methods are not sufficiently exact to secure bacteria, 
 moulds, or any of the smaller micro-organisms. Various instru- 
 ments have been proposed to enumerate and examine the more 
 minute micro-organisms in the air ; but, on the whole, the work 
 in this direction has been imperfectly successful. Perhaps the 
 best method is that with Hesse's instrument. He aspirates air 
 slowly through a wide horizontal glass tube, the interior of which, 
 after careful sterilization by heat and washing with alcohol, is 
 smeared or coated with nutrient gelatine. The air enters through 
 a hole at one end, and at such a slow speed as to allow all the 
 suspended particles to fall upon the gelatine before reaching the 
 other end. On being placed in favourable conditions, the various 
 micro-organisms grow upon the gelatine, and can be subsequently 
 examined as to their precise nature. As a rule, the bacteria are 
 much less plentiful than the moulds and fungi, but in air which 
 has been rendered impure by either respiration or by other effluvia, 
 the exact reverse is found to be the case. 
 
 In carrying out all inquiries as to ventilation, the various facts 
 connected with the temperature and moisture of the air need to 
 be ascertained. These observations will be best made by means 
 of thermometers to measure the heat, and by hygrometers to 
 estimate the amount of moisture present. Details regarding the 
 nature and use of these instruments will be more conveniently 
 given in a subsequent chapter upon meteorology and meteorolo- 
 gical instruments. 
 
 In a room, well ventilated and warmed, the temperature should 
 not fall below 6o° F., the moisture or humidity ought to range 
 between 72 and 77 per cent., while the carbon dioxide, as pre- 
 viously stated, should not exceed i'o part per 1000 volumes of air. 
 
54 WATER. 
 
 CHAPTER II. 
 
 WATER. 
 
 Water is found widely diffused in Nature, and enters into the 
 structure of plants and animals as well as nearly every tissue 
 of our bodies. As a solid, we meet with it in the form of snow 
 and ice ; as a liquid, in the sea, in streams, rivers, and lakes ; 
 while, as vapour, it forms one of the constituents of the atmo- 
 sphere, and of the breath which we exhale from our lungs. It is 
 by means of the water we take in with our food that the solid 
 portions of it are changed and dissolved, and its nutrient prin- 
 ciples enabled to enter into the blood, to enrich it, and thereby 
 build up the body tissues. The supply of water is, therefore, a 
 fundamental necessity, and health depends greatly upon a supply 
 of it, sufficient in quantity and pure in quality. 
 
 Water is a chemical compound, consisting 01 two atoms of 
 hydrogen with one of oxygen, and is formed whenever hydrogen 
 gas or a combustible substance containing hydrogen is burnt in 
 oxygen or atmospheric air. In its purest state it is free from 
 taste and smell, and, between 32 and 212 F., under ordinary 
 atmospheric pressure, is a transparent, tasteless, inodorous, and 
 almost colourless liquid. 
 
 In its liquid state, water is about 770 times more dense than 
 ordinary air, this density being actually at its maximum at 
 39° # 2 F. or 4 C. The density of water is always taken as the 
 standard of comparison in reference to the densities of other 
 liquids or solids. In this country the density of water at a 
 temperature of 6o° F., and at the standard pressure of the atmo- 
 sphere, 29*92 inches of mercury (760 mm.), is usually taken as unity, 
 but on the Continent the temperature of its maximum density is 
 more usually adopted, namely, 39°*2 F. or 4 C. ; if cooled below 
 or heated above this temperature, it expands. Some idea of the 
 weights of certain volumes of water, in terms of both our own 
 system of weights and measures and that of the metric system, 
 will be gathered from the following table : 
 
BOILING-POINT OF WATER. 
 
 55 
 
 Grains. 
 
 Cubic centi- 
 metres at 
 4° cent, as 
 grammes. 
 
 Cubic inches 
 at 6o c F. 
 
 Pounds. 
 
 Gallons at 
 6o° F. 
 
 Cubic feet 
 at 6o° F. 
 
 1 
 
 1 5 '432 
 252*456 
 7000 
 70000 
 
 436495 
 
 1 
 
 i6*3S6 
 
 454*345 
 
 4543 *45 8 
 28315 
 
 O 061 
 1 
 
 27*727 
 277*276 
 I728 
 
 1 
 
 IO 
 
 62*355 
 
 0*0002201 
 
 o*i 
 
 1 
 62355 
 
 0*0000353 
 
 0*016046 
 
 0*16046 
 
 1 
 
 Water possesses a certain amount of elasticity and compressi- 
 bility. This compressibility of water increases as its temperature 
 rises. Water has a high capacity for heat, but yet it is a very bad 
 conductor of heat. When water is heated from below, the heated 
 portions of it expand, and thus, becoming specifically lighter, tend 
 to rise to the surface, while the colder and denser parts of it sink 
 until they, in their turn, being heated, the whole mass acquires a 
 uniform temperature. 
 
 At a temperature of 32 F. or o° C, water becomes solid 
 or freezes, and at the same time suddenly expands; on freezing 
 1 volume becomes 1 '09082, an increase of nearly one-eleventh of 
 its volume, a fact which explains the reason why, during frosts, 
 frozen pipes burst or split, and why damp soils or rocks containing 
 moisture tend to crack during frost. This solid water or ice 
 has a less density than liquid water, its specific gravity being 
 0*91674, consequently ice always floats on the surface of the 
 water, and, since the density of water is greatest at 39°*2 F., or a 
 few degrees above that of freezing, it consequently follows that 
 such portions of it which are cooled below that point or freeze 
 remain at the surface, while the water just below remains a few 
 degrees warmer. 
 
 As already explained in the chapter on "Air," water evaporates 
 from its surface at all temperatures, and its vapour thus formed 
 has a density and tension determined by the temperature. Under 
 the ordinary pressure of the atmosphere, which has also been 
 explained as being equal to 29*92 inches of mercury, water boils 
 at a temperature of 2i2°F. or ioo°C, and is converted into 1672*5 
 times its own volume of vapour, or roughly 1 cubic inch of water 
 yields 1 cubic foot of steam. If the pressure be reduced to nearly 
 that of a vacuum, the boiling-point of water is nearly that of 
 32 F. or o° C. ; but if the pressure be increased, then the tem- 
 perature of the boiling-point is raised, as shown in the following 
 table ; — 
 
56 
 
 WATER. 
 
 Pressure, in 
 
 Temperature of 
 
 Pressure, in 
 
 Temperature of 
 
 atmospheres. 
 
 boiling-point. 
 
 atmospheres. 
 
 boiling-point. 
 
 
 F. 
 
 
 F. 
 
 I 
 
 212° 
 
 8 
 
 3417° 
 
 2 
 
 250-5° 
 
 10 
 
 35 8-8° 
 
 3 
 
 2757° 
 
 20 
 
 418-4° 
 
 4 
 
 293 7° 
 
 25 
 
 439"3° 
 
 5 
 
 307-6° 
 
 30 
 
 457-1° 
 
 6 
 
 320-3° 
 
 35 
 
 472-6° 
 
 7 
 
 3317° 
 
 40 
 
 510-6° 
 
 The boiling-point of water under the ordinary pressure of the 
 air is slightly influenced by the nature of the vessel in which it 
 is heated, and by the smoothness or roughness of its surface. 
 Thus in smooth vessels, like those of glass or porcelain, water 
 boils at a higher temperature than in those with a rough surface, 
 like iron. Water has a remarkable power of dissolving substances, 
 and there are but few substances which water cannot to some 
 extent dissolve. Generally the solubility of solid or liquid sub- 
 stances is increased in proportion as the temperature is raised, 
 but there are exceptions to this rule : in the case of gases, the 
 amount which water can dissolve is largely dependent upon 
 pressure ; and under ordinary pressure it is generally larger in 
 proportion as the temperature is lower. The watery solution of 
 solid substances and of certain liquids and gases have a higher 
 density than ordinary water, but, as a rule, the density of watery 
 solutions of liquids and gases is less than that of water. The 
 freezing-point of water solutions is lower than that of water, thus 
 sea water, which is largely a solution of various salts of magnesium, 
 sodium, and potassium, freezes less readily than fresh water. 
 The boiling-point of water is raised when it contains solid sub- 
 stances in solution, and this to an extent largely proportionate to 
 the amount of substances in solution. 
 
 The latent heat of water is 80 thermal units ; the change of 
 one pound of ice to one pound of water at the same temperature 
 requires as much heat as will raise one pound of water through 
 1 74' 2 F. or 79° C. This quantity of heat represents the latent 
 heat of the fusion of ice or the latent heat of water. 
 
 Quantity of Water required. — The amount oi water used 
 varies very much in different communities, being dependent on 
 the conditions of the place and population. The following are 
 the gross amounts used in some typical communities, for all pur- 
 poses, in gallons per head daily: London 32, Edinburgh 38, 
 Manchester 29, Liverpool 31, Leicester 17, Dublin 35, Glasgow 
 50, Berlin 15 J, Vienna 22, Paris 44. 
 
QUANTITY OF WATER REQUIRED. 57 
 
 Water is required for drinking and cooking purposes, for 
 personal ablution, for the washing of clothes, utensils, and 
 houses, for the cleansing of closets, and for flushing drains and 
 sewers ; these amounts are generally included under domestic 
 supplies. In towns, streets have to be watered, horses and cattle 
 supplied, provision made for extinguishing fires — public fountains 
 and trade purposes generally provided for. Roughly about fifteen 
 gallons per head a day are required for domestic purposes, and 
 about five gallons more for flushing drains and sewers — making 
 twenty gallons; the average for trade and public supplies in 
 towns may be taken at an additional ten gallons. The follow- 
 ing table gives in detail the approximate quantities usually 
 allowed : — 
 
 Gallons daily fear 
 one person. 
 
 Cooking o - 75 
 
 For drinking °*33 
 
 Baths 5*0 
 
 Share of house washing 3*0 
 
 Share of laundry washing 30 
 
 If a general bath add 4'0 
 
 Water-closets 6"o 
 
 Unavoidable waste 2*92 
 
 Total 25*0 
 
 For town purposes, etc 5*o 
 
 Add for manufacturing towns . . . 5*0 
 
 35 'o 
 
 An adult man will drink from 50 to 60 ounces daily, exclusive 
 of the amount of water contained in his so-called solid food; 
 but the quantity varies, depending upon the season of the year 
 and the occupation of the individual. Women and children 
 drink less water than men. With a constant supply in towns 
 there is no doubt considerable waste, and by due economy a 
 smaller quantity would suffice. 
 
 The amount required for animals varies, and depends, as in 
 the case of men, on the food, season, and exertion. During hot 
 weather horses need more water than with a cold season. The 
 following quantities approximate as closely as possible to the 
 amount required : — 
 
 Gallons. 
 
 Large oxen . . 6 
 
 Small oxen 5 
 
 Horses 8 
 
 Mules and ponies 6 
 
 Sheep or pigs 1 
 
 In the army, twenty gallons are allowed daily for each horse. 
 
58 WATER. 
 
 This amount includes that necessary for the washing of both 
 horses and carriages, and seems ample. 
 
 In hospitals a very much larger supply is required, and gene- 
 rally the amount used is double the ordinary supply, the average 
 being from 60 to 70 gallons per head daily. 
 
 Rain Water. — All natural water is derived from the rainfall. 
 From the surface of the sea and from the land, water rises, under 
 the influence of the sun's rays, in the form of invisible vapour ; 
 it forms clouds by being separated from the air, and descends 
 under changes of temperature in the form of rain, dew, mist, 
 snow, sleet, and hail. Part of this water is again evaporated, 
 part flows off in the form of streams and rivers, while part sinks 
 in through cracks and fissures into the earth until it reaches an 
 impermeable stratum, where it forms the ground water, and flows 
 beneath the surface of the ground at varying levels towards the 
 sea or nearest water-channel, or finds its way to the surface in the 
 form of springs. 
 
 Rain water varies with the purity of the atmosphere through 
 which it has passed, and if collected in clean vessels as it falls in 
 the open country, is usually very pure and wholesome. Near the 
 sea it may contain chlorides and sulphates, derived from the sea 
 itself. It is soft, owing to the absence of the salts of lime and 
 magnesia. 
 
 As rain descends through the air it takes up from the atmo- 
 sphere about 2$ c.c of gases per litre, of which about 34 per 
 cent, is oxygen, 64 per cent, nitrogen, and 2 per cent, carbon 
 dioxide. In addition, ammonia is usually present, and any sus- 
 pended matters whien may be floating in the air, so that before it 
 reaches any collecting surface it may have added to it as much as 
 two grains of solid matter in a gallon of water. The average solid 
 impurity in rain water throughout England is 2*4 grains in one 
 gallon of water. In inland districts, especially where large manu- 
 facturing works are carried on, these impurities may be increased 
 by the additions of sulphurous and sulphuric acids, and generally 
 with the products of coal combustion, which may be either sus- 
 pended or dissolved in the air. 
 
 Rain water is very frequently contaminated by impurities taken 
 up from the surfaces on which it falls; such impurities generally 
 consist of bird-droppings, decaying leaves, soot, and such' matters 
 as collect on the roofs of buildings ; if the water is acid it will 
 dissolve lead from the gutters, or zinc, should that metal be 
 present or the water be collected from galvanized iron buildings. 
 In order to prevent the suspended matters passing into the 
 storage tank, a rain-water separator is sometimes used. The 
 separator is made of zinc upon an iron frame, the centre part, 
 
RAIN WATER. 59 
 
 or cantor, being placed upon a pivot ; it directs into the lower 
 waste-pipe the first part of the rainfall, which washes away the 
 impurities from the roof. After a certain quantity (about one 
 gallon on each ioo square feet) has fallen, the separator cants 
 over, and turns the clean water into the storage tank. The 
 separator acts automatically. 
 
 The rainfall varies in different districts. On the east coast 
 of England it is about 20 inches annually, on the south coast 
 30 inches, and on the west coast about 70 inches. The mean rain- 
 fall for England and Wales may be said to be 34*25 inches 
 annually ; for Scotland it is 43 inches, and for Ireland 39 inches. 
 
 The quantity of water which can be utilized from the rainfall 
 may be calculated if the amount of the rainfall and the area of 
 the receiving surface is known. It is necessary to know not only 
 the average quantity which falls in any district, but also the 
 amount which falls in the wettest and driest year. Hawksley states 
 that the average of twenty years, less one-third, gives very accu- 
 rately the amount of rain in the driest year ; and the same average, 
 plus one-third, gives very nearly the amount in the wettest year. 
 The average of the three driest years in twenty is a safe basis on 
 which to calculate the supply. 
 
 It is estimated that one-third of the rainfall flows off the surface 
 and finds its way directly into streams and rivers, one-third is taken 
 up by vegetation or evaporated, and the remaining third sinks 
 into the earth ; but this can hardly be even an approximation to 
 the truth. The available rainfall for storage will depend rather 
 on the nature of the soil, the inclination of the ground, the tem- 
 perature and moisture of the air, and the presence or absence of 
 vegetation. On an average six-tenths of the rainfall is available 
 for storage. 
 
 A simple method for calculating the amount of water given by 
 rain is to multiply the area of the receiving surface in square feet 
 by half the rainfall in inches, the result is expressed in gallons ; 
 the error here is only about 4 percent. One inch of rain delivers 
 101 tons by weight, or 22,617 gallons on each square acre. If 
 the inches of rainfall be multiplied by 14-j, the result equals the 
 millions of gallons per square mile. 
 
 Springs and Rivers. — Rain, flowing over and through the 
 land, supplies springs and rivers. The amount which flows off the 
 surface in streams or which penetrates into the ground depends 
 on the configuration of the surface, the nature of the soil, the 
 season and temperature, and, to a lesser extent, on the movement 
 of the air. In summer, owing to an increase of temperature, 
 evaporation is rapid, and less water penetrates the surface or runs 
 off in the direction of the natural watercourses than in winter; 
 
6o 
 
 WATER. 
 
 the ground is drier, and more readily absorbs moisture. Evapora- 
 tion is 50 per cent, less on a flat district than on an undulating 
 rocky country. In a clay district hardly any water will sink into 
 the ground, while a very large amount infiltrates into a loose sand 
 
 FiG. 13. — Diagram showing the tapping of the ground water 
 above and below an impermeable stratum. 
 
 or gravel soil. In the magnesium limestone districts about 20 per 
 cent, of the rainfall penetrates into the ground ; in the new red 
 sandstone, 25 per cent. ; in the chalk, 42 per cent. ; and in loose 
 sands, 96 per cent. 
 
 Penetrating into the ground, rainfall absorbs carbon dioxide 
 from the air as it passes through the interstices of the soil, 
 which is nearly 250 times richer in this gas than the air above 
 it ; aided by this, by the temperature of the soil and by pressure, 
 it dissolves from the soil limestone and as much soluble matter, 
 
 Deep 
 
 Surface 
 tft'e// 
 
 Spr/ha 
 
 Fig. 14. — Diagram illustrating various sources of water. 
 
 from the strata through which it passes, as can be taken up in the 
 
 time. 
 
 It also takes up organic matter from the soil, more especially 
 when it falls on cultivated lands and inhabited areas, and the 
 organic acids derived from this organic matter, aided by increased 
 temperature and pressure, increase the solvent properties of the 
 water by exercising a powerful chemical action on the substances 
 present in the soil and underlying rocks. 
 
 Springs are the outcrop or overflow of the ground water. The 
 
SOURCES OF WATER. 6l 
 
 rain which falls on a permeable stratum percolates downward until 
 it is arrested by a bed of clay or other impermeable stratum, and 
 there becomes stored underground until it rises to a point or level 
 at which it can spontaneously appear at the surface. 
 
 Mineral springs yield water containing dissolved mineral 
 matters in solution which render them unfit for ordinary drinking 
 purposes, though they possess medicinal properties of great value. 
 
 River water is derived partly from springs, but its chief source 
 is from that part of the rainfall which flows off from the surface 
 of the ground. If the supply is taken from the head waters or 
 source of the river before impurities can gain access to the water, 
 it is generally pure, and the water has all the characters of an 
 upland surface water. Unfortunately, most rivers are subject to 
 pollution in their course, either from drainage from cultivated 
 lands or from the sewage of villages on their banks being per- 
 mitted to pass into them. The composition of the water will 
 therefore vary according to the part of the river whence it is 
 taken. As a rule the dissolved mineral constituents in river 
 water are in less quantity than in the spring water, but the organic 
 matters are present in greater quantity. Besides dissolved matters, 
 river water usually contains suspended matter, both organic and 
 inorganic, living and dead. 
 
 The organic matter which thus gains access to the water is to 
 some extent oxidized and rendered innocuous in those rivers in 
 which the current is rapid and where the water in its flow is broken 
 up by rocks and boulders and exposed to the action of the air ; the 
 presence also of aquatic and bacterial life assists in its purification ; 
 but even then this is no safeguard when sewage is permitted to 
 foul the water. Rivers or streams are sometimes dammed up so 
 as to form an impounding reservoir, as in the case of the Vyrnwy, 
 supplying Liverpool, and the Vartry at Dublin. These waters 
 afford good supplies provided the gathering grounds are efficiently 
 protected. 
 
 Wells are either shallow wells or deep wells. A well of 50 
 feet in depth or less is generally regarded as a shallow well ; one of 
 100 feet or more, as a deep well. Shallow wells draw their supply 
 from the subsoil water, while deep wells tap the water-bearing 
 stratum beneath the impervious stratum : the latter are sometimes 
 of great depth, and are called Artesian wells, having been first 
 sunk in the province of Artois, in France. The water from these 
 wells is generally pure, but it is not unusual to find in it a large 
 amount of chloride of sodium and a good deal of free ammonia ; 
 it is generally poor in oxygen, not well aerated, but is moderately 
 palatable. Deep-well waters are much harder than other classes of 
 water, for they dissolve out much calcium, magnesium, and the 
 
62 
 
 WATER. 
 
 alkaline salts in their long course underneath the surface of the 
 
 ground. 
 
 Wells furnish water supplies to most rural districts, and their 
 depth generally depends upon the nature of the soil and on the 
 height of the underlying ground water. Shallow wells may yield 
 good water provided there is no risk of pollution from surface 
 washings or from their proximity to drains and cesspools, but in 
 every case it is wise to go deep enough to place an impervious 
 stratum between the water supply and the surface of the ground, 
 
 and thus to effectually shut 
 
 ~- to pump 
 
 - Cover 
 
 WaterChannel 
 
 i 
 
 M..JM 
 
 Mi' 
 
 | 
 % 
 
 . A. 
 
 f 
 
 
 tr=i 
 
 T C 
 
 I 
 
 •-ti- i 
 
 Fig. 15. — Suitably constructed well 
 
 
 
 1 
 
 Iff 
 
 ■ . 
 
 off surface impurities from 
 
 entering and fouling the 
 
 water in the well. If this 
 
 p- cannot be done, the well 
 
 ;.v£| -Concrete should be sunk as deep as 
 
 possible into the water- 
 bearing stratum, and pro- 
 tected by steining with 
 brick and cement, this 
 being carried sufficiently 
 high above ground to pre- 
 vent surface washings from 
 entering the well (Fig. 15). 
 The distance drained 
 by wells is undetermined : 
 it has been given as a circle, 
 the radius of which is 
 the depth of the well, but 
 there are good grounds for 
 believing that much larger 
 areas are affected, and that 
 the flow of water has been 
 influenced at a distance 
 many times the radius ; the 
 pressure of tidal rivers has 
 been known to affect the quantity and quality of the water in 
 wells at a distance of 1000 yards. Wells are largely influenced 
 by the nature of the soil, by the movement and direction of the 
 ground water, and by the amount of water drawn from them. A 
 porous soil with no impervious superficial stratum will admit of 
 impurities reaching the well from the surface which a clay soil 
 would shut off. The movement and course of the ground water 
 being in the direction of the nearest watercourse or the sea, to 
 protect the water supply from any soakage from leaky cesspools 
 or other sources of pollution, the well should be placed above 
 
COLLECTION AND STORAGE OF WATER. 63 
 
 them, to windward, as it were, of all such possible sources of 
 contamination. 
 
 A well which yields a moderate quantity of good water may, 
 if the demand on it be increased, draw in water from the surround- 
 ing parts to meet the supply, and thus tap sources of impurity 
 which a moderate demand left untouched. A sudden rise in the 
 ground water may also lead to direct communication between a 
 cesspool and a well, by the water tapping the former in its flow. 
 
 Tube wells are used when a temporary supply is required : 
 they are superior to dug wells, which, from imperfect steining, or 
 total absence of it, are liable to become foul from surface pollution. 
 They are constructed by driving tubes into the soil, one length 
 being screwed on to another, the first tube being perforated at 
 the bottom for about two feet, its lower end being furnished with 
 a steel point. When the subsoil water is reached, a pump is 
 attached to the tube ; the water after pumping a short time is 
 clear. 
 
 Collection and Storage. — When water is required for towns 
 it is generally collected in reservoirs and distributed by gravi- 
 tation. The amount required depends on the quantity used and 
 the ease of replenishing. When these conditions are known, it is 
 easy to calculate the space required ; thus, if the number of 
 gallons used daily be divided by 6*23 we get cubic feet, and these 
 multiplied by the number of days for which the storage must 
 last, gives the necessary size of the reservoir in cubic feet. 
 Experience shows that the storage supply in this country should 
 be not less than 150 days' consumption. Hawksley's formula 
 
 for storage is D = —p== • where D is the number of days' supply 
 
 to be stored and /is the mean annual rainfall in inches. Thus, 
 
 IOOO IOC 
 
 with a rainfall of 36 inches annually, we get D = -y= = —7 
 
 v 36 ° 
 
 days' supply. 
 
 Reservoirs are placed on as high ground as possible, to give 
 a sufficient head or pressure of water, so that every part of the 
 district may be supplied by gravitation ; from thence the water 
 is distributed by cast-iron pipes. Service reservoirs should be 
 covered and ventilated, and the water from the supply reservoir 
 carefully filtered through filter-beds of sand before it is permitted 
 to enter the service reservoir for distribution. In form they 
 should be deep rather than extended, as this lessens evaporation 
 and secures coolness. In case of ground supplies obtained from 
 wells or springs, the water is generally free from organic growths, 
 and in storing it in service reservoirs it is only necessary that 
 no opportunity should be given for the growth of organisms. If 
 
 IOOO IOOO 
 
 = 100 
 
64 WATER. 
 
 the supply is taken from surface water there is usually some organic 
 growth present, and the water has to be freed from this by filtration, 
 so as to convert it into a ground water, and then in both cases to 
 protect it from the action of light ; it is now recognized that the 
 growth of fungi in water, stored in reservoirs, can be prevented by 
 the exclusion of light. All reservoirs require periodical cleaning. 
 
 If the storage reservoir is so large that it cannot be covered in, 
 a second or service reservoir, capable of holding a few days' 
 supply, should be provided, into which, after filtration, the water 
 from the storage reservoir might be conveyed as required. 
 
 Distribution. — Water collected as thus described may be 
 distributed on the constant system, in which the supply pipes are 
 always kept full of water, or on the intermitte?it system, in which 
 the water is only turned on at intervals for a short time during the 
 day. The constant supply is the one usually aimed at, as no 
 cisterns are required for storage, and the drinking water is taken 
 direct from the main. When the supply is intermittent it is 
 necessary to have cisterns in which to store a sufficient supply 
 of water during the intervals that the water in the mains is 
 turned off; the mains, being empty of water, are liable to be fouled 
 by impurities in the soil, such as gas from leaky pipes lying in 
 their vicinity, or actual sewage from a neighbouring leaky sewer 
 or drain-pipe ; the foul air, aided by the suction action of the 
 pipe when the water is turned off, enters through the joints, which 
 are not infrequently caulked with tow and gaskin, and are not 
 impervious. Under proper supervision the waste of water is less 
 on the constant system than on the intermittent system of supply. 
 
 Water is usually distributed by iron pipes, called mains, laid 
 some distance underground, the thickness of the pipe being 
 dependent on the pressure to which it is subjected by the head of 
 water. The lengths of pipes are put together by a spigot joint 
 packed with lead. The practice of caulking with tow and gaskin 
 and then running the joint with molten lead seldom secures a 
 proper joint; the tow and hemp rot, and contaminate the water 
 as well as causing waste from leakage. Cast-iron pipes, unless 
 protected, rapidly corrode, especially if the water is soft. It is 
 usual, therefore, to coat these pipes with a protective material 
 before laying them down. Angus Smith's process is the one very 
 generally adopted. A varnish distilled from coal tar until the 
 naphtha is entirely removed is deodorized and a small quantity of 
 linseed oil added ; this mixture is carefully heated in a tank to 
 about 400 F., when the pipes are immersed in it, and allowed 
 to remain until they attain a temperature of 400 F. Some 
 engineers prefer Barffs method, which consists in raising the 
 temperature of the metal to about 1200 F. — a white heat — in 
 
DISTRIBUTION OF WATER. 65 
 
 a suitable chamber, into which is passed super-heated steam ; the 
 metal is exposed to this action for several hours, and becomes 
 coated with a protective oxide ; this plan has not hitherto proved 
 very successful. Iron pipes last longer if kept constantly full of 
 water, and are not so liable to corrode as those which are alternately 
 full of air and water. 
 
 The disadvantage of the constant-supply system is the greater 
 waste from leaky pipes, due to settling of the ground after laying, 
 to fracture from pressure owing to heavy traffic, and the expense 
 of the renewal of the fittings, which must be of the best descrip- 
 tion ; but in practice it has been found that with proper fittings 
 there is no great loss. A plan has been introduced by Deacon 
 by which any large waste occurring in any district may be at 
 once detected. He employs a water-waste meter, or detector, 
 which registers the flow of water both by day and by night. 
 These are fitted to each district main, and as only a very 
 limited quantity is used at night, any waste can be at once 
 detected, since what passes through the meter must run to waste. 
 The place where the leakage occurs can be localized by the 
 vibrations produced in the nearest house-pipes, and which are 
 audible on applying the ear to the stand-pipe. By this method 
 leakage can be at once found out, and an enormous saving of 
 water effected. 
 
 Service-pipes communicating with houses are made of lead, 
 wrought iron, or galvanized iron ; lead pipes should only be used 
 when it has been proved that the water has no action on that 
 metal. Soft waters are especially liable to act on lead, an oxide 
 of lead being formed which is dissolved again ; for such waters, 
 composition pipe, made of an amalgam of lead and tin, has been 
 used, and is said to answer. Iron pipes coated with vitreous glaze 
 are best, and have proved successful when all others have failed, 
 but on account of the difficulty in fixing them, and their cost, 
 they have not come into general use. Galvanized-iron pipes are 
 now very generally used ; they are not liable to rust, and stand 
 the pressure of the water well. Block-tin pipes are excellent, but 
 very expensive : water does not act on them, and they last for 
 a long time; their cost, however, is almost prohibitive against 
 their coming into general use. Composite pipes, consisting of 
 block tin enclosed in a lead pipe, are not liable to be acted on 
 by water, but if the surface of the tin is fissured, either in fitting 
 the pipe or by frost, galvanic action takes place, and the lead is 
 rapidly dissolved ; they are, however, said to answer where they 
 have been used. The best service-pipes for general use are 
 wrought-iron pipes protected with Angus Smith's preservative : 
 
 D 
 
66 WATER. 
 
 if pipes coated inside with a vitreous glaze are not considered too 
 expensive, this latter is a perfect material, as it is not affected by 
 acids in the water, and does not yield any unpleasant taste to 
 water. The action of water on iron pipes appears to diminish 
 after their use for a short time. 
 
 Cisterns are usually made of slate, stone, iron, galvanized 
 iron, or lead ; the latter should never be used when the water 
 supply is taken for drinking purposes. Slate, set in good cement, 
 is an excellent material, but is liable to leak at the joints ; in no 
 case should red lead be used to repair these cisterns. Common 
 mortar should not be used, as it gives up lime to water. Stone- 
 ware makes a good cistern, but its weight is against its use. Iron 
 cisterns rust and discolour the water ; they may, however, be pro- 
 tected by being lined with cement (Crease's patent). Galvanized- 
 iron cisterns are those most generally used ; they have been known 
 to give up zinc to water, but this is so exceptional that it should 
 not prohibit their use. They should, however, be thoroughly coated 
 with a good asphaltum paint. Cisterns should be so placed as to 
 be easy of access and readily cleaned. If the water is exposed to 
 frosts, the sides should be made to slope : this will prevent their 
 fracture by the expansive force of the freezing water. The overflow 
 or waste-pipe should not communicate with any drain, but open 
 free to the air above a grating sufficiently high to prevent foul 
 air rising through it and contaminating the water. For the same 
 reason the supply pipe of any water-closet should not pass direct 
 from the cistern, but a smaller cistern (water-waste preventor) 
 should intervene. 
 
 To permit of cisterns being periodically cleaned, it is better 
 to have two smaller cisterns than one large one, so that there 
 may be no inconvenience in emptying the one or the other at 
 any time. Cisterns should always be covered to protect them 
 from dust, soot, and other contaminations, as dead mice, birds, 
 etc. ; they should also be ventilated and protected as far as possible 
 from both heat and light. Tanks to hold rain water require even 
 more constant care than cisterns, as the water carries impurities 
 with it from the roofs of buildings, from which it is generally 
 collected. 
 
 With an intermittent supply, the cisterns in the smaller class 
 of houses are not large enough to fulfil the requirements of the 
 occupants, and stand-pipes are generally erected to supplement the 
 supply ; the need of these is avoided where the constant service has 
 been introduced, and the evils attendant upon the storage of water 
 are thereby prevented. A great waste has often followed on the 
 change from the intermittent to the constant service, mainly due 
 to the fittings not being able to stand the greater strain placed 
 
ACTION OF WATER ON LEAD. 6? 
 
 on them ; constant supervision is required to see that this is not 
 a cause of waste. Screw-down taps should always be provided, 
 and not a common stopcock, as there is less pressure on the 
 pipe when the water is turned off slowly. The water drawn 
 direct from the main is cooler, and, as a rule, better aerated than 
 when stored in cisterns. A screwcock to turn off the water just 
 as it enters the house is also necessary, so as to shut off the supply 
 if needed ; this is very essential during frost, and, if supplemented 
 by a tap at the lowest part of the pipe so as to enable the water 
 to be drawn off, there will be little danger of pipes bursting from 
 this cause. 
 
 Pipes, if made of lead, should be sufficiently strong to stand 
 the strain of high-pressure supplies; they are usually 9 lb. per 
 yard for i-inch pipes, and 21 lb. per lineal yard for 2-inch 
 pipes. In order to limit waste, many companies propose to 
 deliver in special cases water by meter, but this would have the 
 disadvantage, if applied to communities, of restricting the use of 
 water, which is not advisable. The advantages of the constant 
 service in the case of fire is obvious. 
 
 Action of Water on Lead. — The apparently inscrutable 
 behaviour of certain waters, especially soft moorland waters, in 
 regard to plumb o-solvent ability, may be said to be now under- 
 stood. For this explanation we are indebted to the work of 
 Houston. Preliminary inquiry had shown that the plumbo- 
 solvency of any water was associated always with corresponding 
 variations in the amount of acid in the water. Extended inspec- 
 tion and investigation of all the chief moorland gathering grounds 
 has shown that the cause of the plumbo-solvency is due to the 
 acid in the waters, which acid is formed by contact of the water 
 with the moist peat on the catch-ground, and that the formation 
 of the acid is due to the presence of acid-producing bacteria in the 
 peat itself. An important point brought out is a difference in 
 kind of action exercised by water on lead. In one case the action 
 (plumbo-solvency) is brought about by acidity of the water; in 
 the other the action (erosion) is an inherent property of water 
 containing dissolved air. The erosive action, as distinguished 
 from the true solvent action of acid waters, shows itself by the 
 formation of a relatively insoluble compound or powder "(hydroxide 
 of lead), which may tend to fall away from the surface of the 
 metal, and so permit of progressive action. Fortunately, however, 
 erosion takes place only to any large extent when the lead is 
 bright, and, moreover, most natural waters contain ingredients 
 which prohibit the action. Neutral distilled water erodes lead 
 vigorously. Interesting as this phase of the subject is, it is quite 
 secondary in practical importance to the question of plumbo- 
 
68 WATER. 
 
 solvent ability, which is due to acid in the water derived from 
 acid peat, and formed by acid-producing bacteria in the peat 
 itself. 
 
 As to remedial measures, the experiments seem to indicate 
 that in practice it might be cheaper to resort to a preliminary 
 lime or combined lime and sand nitration treatment than by 
 employing carbonate of sodium, by this means correcting acidity, 
 plumbo-solvent ability, and gross erosive power, and then supple- 
 menting this procedure finally with a further addition of sodium 
 carbonate in minimal quantities, so as, by endowing it with a 
 reserve of protective substances, to place the water in a condition 
 in which the possession of erosive ability would be impossible. 
 There seems to be this difference between erosion and plumbo- 
 solvency, that any mere neutralizing treatment, even if carried out 
 imperfectly, always renders an acid water, as regards plumbo- 
 solvency, less dangerous than before ; whereas, as regards erosive 
 ability, insufficient treatment may produce no appreciable inhi- 
 bition, and may in certain cases render such partially treated 
 water more prone than before to attack lead. In cases where 
 doubt exists as to the plumbo-solvent ability of a water, it is sug- 
 gested that to be deemed " safe " it should give a neutral reaction 
 with lacmoid solution of an ascertained activity, and also fail to 
 dissolve an appreciable quantity of lead when filtered through a 
 glass tube containing lead shot. Similarly, all doubtful waters 
 should be tested as regards erosive ability by placing them in 
 contact with bright lead. A water containing as much as yj> of a 
 grain in the gallon is unfit for drinking purposes, and even -^ of 
 a grain may be unsafe, as this amount has been known to affect 
 some persons. Filtration removes lead from water, if the filters 
 act properly. 
 
 Quality of Water Supplies. — Rain water, if properly collected 
 and stored, affords an excellent supply in country districts. In 
 towns it takes up such impurities from the air and from the various 
 collecting surfaces on which it is gathered, that it cannot be looked 
 upon as satisfactory. The uncertainty of the supply and the 
 length of a dry season necessitates large storage capacity, which 
 is not desirable. Rain water should be filtered to remove sus- 
 pended matters before being stored, and the tanks protected from 
 light and heat. The hygienic value of rivers, springs, and wells 
 as sources of supply depends on many details. Spring water 
 may be both pure and impure ; it is generally, however, free from 
 organic impurity, while its mineral constituents are large. River 
 water, on the contrary, is more liable to vegetable and animal 
 contamination than springs are, while its mineral constituents are 
 less. Shallow-well water should always he viewed with sus- 
 
 
QUALITY OF DRINKING WATER. 69 
 
 picion, by reason of the danger from surface pollution during 
 heavy rainfalls. 
 
 Hard and Soft Waters. — Water is frequently described as 
 hard and soft. Hardness is due to the presence in the water of 
 the salts of calcium and magnesium. If it is in the form of 
 carbonates, and if its amount is not excessive, it renders water 
 palatable, and does not interfere with its wholesomeness ; but if, 
 on the other hand, it is caused by the sulphates of calcium and 
 magnesium, it is objectionable. Hard waters are also wasteful, 
 as in washing much soap is expended before a permanent lather 
 is obtained. Vegetables boiled in such water tend to become 
 hard, and are difficult to digest. The difficulty of infusing tea 
 with such water is well known. 
 
 The following classification show the characteristics of water 
 from different sources {Rivers Pollution Com?nissioners' Report) : — 
 
 1. In respect of wholesomeness, palatability, and general fit- 
 ness for drinking and cookery — 
 
 Wholesome 
 
 ( 1. Spring water 1 11, 
 
 2. Deep-well water \ sex l Potable. 
 
 I 2. Upland surface ) , , , , . 
 
 f4. Stored rain water j m °derately palatable. 
 
 Suspicious \ 5. Surface water from cultivated ^ 
 
 lands / 
 
 6. River water, to which sewage > palatable, 
 gains access 
 
 7. Shallow-well water 
 
 Dangerous ~\ gains access I 
 
 2. Classified according to softness with regard to washing, etc. — 
 1. Rainwater. 2. Upland surface water. 3. Surface water from 
 cultivated land. 4. Polluted river waters. 5. Spring water. 
 6. Deep-well water. 7. Shallow-well water. 
 
 3. As regards the influence of geological formation in render- 
 ing the water sparkling, colourless, palatable, and wholesome, the 
 following water-bearing strata are most efficient : — 
 
 1. Chalk. 2. Oolite. 3. Greensand. 4. Hastings Sand. 
 5. New Red and Conglomerate Sandstone. 
 
 The general characters of a pure and wholesome water are as 
 follows. It should be clear, sparkling, showing that it is well 
 aerated, free from colour and taste, and not too hard, so as to 
 interfere with the cooking of vegetables, etc. There should be 
 no sediment, and if any, it should consist only of a little mineral 
 matter. Where there is any marked deviation from this standard, 
 the cause of it should be carefully inquired into. 
 
 Impurities in Water. — The geological formation of a district 
 influences the composition of the water which passes through it ; 
 
JO WATER. 
 
 while affording a valuable guide, it by no means tells with 
 absolute certainty what the constituents of the water may be. 
 The following soils generally yield a supply of pure water : — 
 granite, metamorphic and clay slate soils, hard oolite and chalk. 
 Water from these soils is usually very pure, containing a little 
 carbonates and sulphates of calcium and magnesium, but a very 
 small amount of organic matter. Waters from the sands, sand- 
 stones, and gravels vary greatly in composition, and are uncertain 
 sources of supply ; the greensand waters are usually good, and in 
 clean gravels, if not situated near towns, the water is often free from 
 impurities. Sometimes the sands contain large quantities of 
 soluble salts, which are dissolved by the water ; frequently, also, the 
 organic matter is high. The limestone and magnesium limestone 
 waters are usually free from organic impurity, but may contain the 
 fixed hard salts — calcium sulphate and magnesium sulphate — in 
 excess ; they are not as desirable a source as the chalk waters. 
 
 The chalk waters are clear, sparkling, well aerated, being 
 highly charged with carbon dioxide ; there is usually a very small 
 amount of organic matter present, and, although hard, they can 
 be very effectually softened ; they are wholesome waters, as a 
 class, and are pleasant to drink. Fissures sometimes exist in the 
 chalk, by which impure water may be admitted to wells without 
 having undergone any process of nitration. 
 
 Surface and subsoil water are a common source of supply in 
 country districts; these waters should always be regarded with 
 suspicion, unless taken from places which are far removed from 
 possible pollution. In gravelly and sandy soils, the power of 
 oxidation is so great that organic impurities become rapidly 
 oxidized and rendered harmless. Such waters are always 
 dangerous, although possibly they may not be actually injurious. 
 Marsh waters are soft and well adapted for washing purposes, but 
 the vegetable organic matter is high, and there is usually much 
 suspended matter present. 
 
 Artesian-well water varies ; it frequently contains an excess 
 of sodium chloride and carbonate, and there is usually present 
 free ammonia in considerable quantities ; it is generally flat and 
 insipid, and for this reason is not very palatable. 
 
 Wells situated near the sea-coast usually contain a large 
 amount of saline mineral matter. In cases where this is excessive, 
 surface wells and rainfall afford the only available sources of 
 supply. 
 
 Effects of drinking Impure Water. — Although it is a generally 
 recognized fact that any large and sudden outbreak of epidemic 
 disease in a community, especially if it is localized, is usually due 
 to the pollution of the water supply, yet there are many instances 
 
EFFECTS OF DRINKING IMPURE WATER. 7 1 
 
 on record where its use has been the cause of ill-health, without 
 producing such marked effects. The diseases which are asso- 
 ciated with the use of impure water are cholera, enteric fever and 
 dysentery, dyspepsia and diarrhoea, goitre, parasitic diseases, and 
 metallic poisoning. The virulence of an epidemic disease has 
 some definite relation to the purity of the supply, for, once seeded 
 with the specific poison, a polluted water appears to act more 
 virulently than one that is pure. From our knowledge of the 
 presence of infective micro-organisms, it would appear doubtful 
 whether they survive in good water for any lengthened period. 
 Laboratory experiments show that from 14 to 40 days has been 
 the maximum period of their vitality, and probably under less 
 favourable conditions a much shorter period would complete 
 their life. 
 
 Waters containing an excess of the fixed hard salts of calcium 
 and magnesium frequently cause diarrhoea and dyspeptic 
 symptoms, especially among those who are unaccustomed to use 
 them. Carbonate of calcium does not appear to have any in- 
 jurious effect, nor, on the contrary, is it essential, as it was 
 formerly believed to be ; if it is, it is best to have it in some other 
 way than in drinking water. Diarrhoea has been caused by the 
 suspended matters in water, which affect the intestinal tract by 
 mechanical irritation. Waters to which sewage gains access may 
 produce diarrhoea in those who are not used to them, though long 
 habitude in the use of such waters appears to induce a condition 
 in which the system tolerates them. Goitre is a disease said to be 
 caused by drinking water derived from limestone and dolomitic 
 rocks ; that goitre is prevalent in places where the water is very 
 hard is undoubted ; but it is also said to exist where the drinking 
 water is soft. Modern opinion inclines to the view that the real 
 cause of the disease is a micro-organism which, gaining access to 
 man by means of water which has percolated through a porous 
 and organically polluted soil, subsequently so disturbs the function 
 of the thyroid gland as to set up the condition known as goitre. 
 The whole question is still obscure. 
 
 That dysentery has been caused by impure water there is 
 ample evidence to prove ; in nearly every instance, the water was 
 polluted with faecal, and probably with dysenteric discharges, 
 and where the supply was discontinued, the disease disappeared ; 
 it may also be said that water contaminated with much 
 suspended matter acts as a predisposing cause by exercising 
 an irritative action on the bowels, as well as being directly 
 the vehicle by which the specific poison is introduced into 
 the system. 
 
 Enteric fever is certainly often spread by impure water. In 
 
72 WATER. 
 
 outbreaks of this nature a suggestive premonitory sign is the 
 prevalence of diarrhoea. The most notable enteric fever out- 
 breaks in which polluted water was shown clearly to be the 
 causative agent have been those at Worthing, Maidstone, Cater- 
 ham, Middlesbrough and the Tees valley. 
 
 Cholera is another disease propagated frequently by means of 
 drinking water infected with the specific micro-organism. The 
 evidence of its spread by this means is overwhelming both in 
 Europe and India. As with enteric fever, so with cholera, the 
 infection gains access to the water by the discharges of those 
 suffering from the disease being allowed to enter defective sewers, 
 leaky cesspools, privies, etc., the contents of which infect the sub- 
 soil water or are carried direct into rivers, streams, and wells, from 
 which drinking water is taken. 
 
 Ova of parasitic intestinal worms are frequently found in water, 
 and may gain access to man by drinking or bathing. The more 
 common forms are as follows : — Taenia solium, Ascaris lumbricoides 
 (round worm), Tcenia mediocanellata, Bothriocephahis latus, Disto- 
 mum hepaticum (liver fluke of sheep), Oxyuris vermicularis (thread- 
 worms). Also in tropical countries, the Filaria sanguinis /wminis, 
 the Filaria medinensis, the Bilharzia hcematobia, and the A?icky- 
 lostoma duode?iale. 
 
 Metallic poisoning may result from the absorption by the 
 water of the metal used in the making of the service-pipeSj 
 cisterns, etc., by means of which the water is supplied or stored. 
 The water may also be contaminated at its source by passing 
 through a soil in which a metal is present, as in some mining 
 districts, or a river may be polluted with metallic refuse from trade 
 manufactures. Copper, zinc, lead, and arsenic are the most 
 probable poisonous metals which may gain access to water in 
 this way. 
 
 Purification of Water. — This subject may be considered in 
 relation to (a) purification of water on a large scale as applicable 
 to public water companies, before distribution of the supply, and 
 (b) to domestic filtration as usually practised by the consumer in 
 his own house. Water derived from the chalk undergoes a 
 process of purification when the salts of calcium are removed from 
 the water before distribution for the purpose of rendering the 
 water soft. Several methods have been used, but the basis of all 
 of them is the addition of a measured quantity of milk of lime, 
 calculated on the degrees of hardness of the water. Carbonates 
 of calcium and magnesium are soluble in water containing free 
 carbon dioxide. When a solution of fresh slaked lime is added 
 to such a water in proportion to the degree of hardness present, 
 the calcium combines with the excess of carbon dioxide to form 
 
PURIFICATION OF WATER. 73 
 
 carbonate of calcium, which is precipitated with almost the whole 
 of the carbonate of calcium originally held in solution by the 
 water, and falls as a sediment, carrying down with it the organic 
 impurities held in suspension ; this action of adding lime-water to 
 remove the mineral matters (the salts of calcium and magnesium) 
 from a water may be expressed as follows : — 
 
 CaC0 3 + C0 2 + CaH 2 2 = 2 CaCO a + H 2 
 
 It is necessary to know the exact degrees of hardness in the 
 water, and to use only sufficient milk of lime as will combine with 
 the carbon dioxide holding the chalk in solution, otherwise calcium 
 passes out into the distributing pipes. If an excess has been 
 added, a few drops of a solution of nitrate of silver added to a 
 small quantity of the water will produce a dark yellow colour, 
 but only a white precipitate, if chlorides alone are present. The 
 amount of slaked lime added averages about i ounce per ioo 
 gallons for each degree of temporary hardness. This treatment 
 usually leaves only the permanent hardness plus some two grains 
 per gallon of calcium carbonate in solution. In the Porter-Clark 
 process, the suspended matters are removed by allowing the water 
 to pass through a series of linen cloths under pressure. This has 
 the advantage of rapidity, and removes the whole of the suspended 
 matters effectually. 
 
 The permanent hardness of water is not touched by this 
 process ; this hardness is due to the soluble salts of calcium or 
 magnesium held in solution by the solvent properties of the water 
 itself 
 
 For the reduction of permanent hardness, the addition of 
 sodium hydroxide is needed : thus — 
 
 CaSO, + 2 NaOH = Ca(OH) 2 + Na 2 SO, 
 
 In waters where great permanent hardness is due to calcium 
 salts, then sodium carbonate must be used instead of the 
 hydroxide. In both cases, the addition of lime is needed for 
 removal of the temporary hardness. Practically, each degree of 
 hardness, as CaC0 3 , is equal to o - 8 part NaOH, 0*56 part CaO, 
 074 part Ca(OH) 2 , ro6 part Na 2 C0 3 , and, for general use, the 
 following rules may be laid down : — 
 
 (1) If the temporary hardness exceeds the permanent hard- 
 ness, add NaOH equivalent to the permanent hardness, and 
 lime equivalent to the excess of temporary over permanent hard- 
 ness. 
 
 (2) If the permanent hardness due to lime exceeds the 
 temporary hardness, add Na 2 CO a in proportion to the permanent 
 
74 WATER. 
 
 hardness, and then, if necessary, CaH 2 2 equal to the temporary 
 hardness. 
 
 There are various patent processes in use, such as the Stan- 
 hope and Hewetson, which act on the same chemical principles. 
 Another is the Maignen, which treats the water with anticalcaire } 
 an agent containing calcium, sodium carbonate, and alum. The 
 Lawrence process of softening is both ingenious and effective, its 
 essential agency is by boiling which both softens and sterilizes the 
 water. That known as the " Permutit " system of softening water 
 employs a compound of silicon, alumina, and sodium ; its essential 
 property is base exchange, since as the water passes through the 
 medium the calcium and magnesium are taken up and the sodium 
 salts are freed. The action is automatic and when the " permutit " 
 is exhausted it can be regenerated by a 10 per cent, salt solution, 
 by which the calcium and magnesium are eliminated as chlorides 
 and the reformed soda-permutit ready again to treat more hard 
 water. Manganese-permutit is effective for removing iron from 
 water. 
 
 Water is nearly always submitted to some process of storage 
 and filtration before distribution ; it is extremely difficult to 
 obtain at its source a water which needs no purification, and 
 in the great majority of cases it is impossible to do so. Water 
 is usually first passed into large reservoirs, where the suspended 
 matters are allowed to subside by gravitation ; these consist of 
 mineral grit and clay in a state of fine subdivision and sand, all of 
 which forms a deposit on the bottom of the reservoir. Recent 
 experiences indicate that the advantages accruing from even a few 
 days' storage are very great ; this is especially true of river water. 
 The improvements brought about by storage of water in large 
 reservoirs for from one to four weeks are of a general character, 
 and are not limited to the elimination of danger from pathogenic 
 micro-organisms. From the storage reservoirs, the water is led 
 to filter-beds made of sand and coarse gravel, the former being 
 from two to three feet in thickness, and lying on three or 
 four feet of coarse sand and gravel, and from this the water is 
 collected into a storage reservoir for distribution. Downward 
 filtration is much more effectual than the upward or lateral passage 
 of the water through the filter. To secure satisfactory bacterial 
 purity the maximum rate of filtration should not exceed 4 inches, 
 or 2*1 gallons per square foot of filter surface per hour. By these 
 processes two means are employed to purify the water, viz. 
 mechanical and chemical. The mechanical processes consist 
 in allowing the heavier particles to subside, and subsequently 
 arresting the suspended matters on the surface of the filter-beds. 
 Sand filtration has not much effect on the chemical constituents 
 
PURIFICATION OF WATER. 75 
 
 of the water, but oxidation of the organic matter does to a limited 
 extent follow on passing water through sand niters. The chemical 
 changes produced on water by nitration have up to a recent 
 period been almost the sole test as regards the capability of the 
 material to purify water ; recent investigations show that all that 
 is really necessary is that mechanical filtration shall be perfect. 
 Sand, although its effect on the organic constituents in water, as 
 gauged by chemical analysis, is limited, is very effective in holding 
 back micro-organisms, which, if they are not the actual cause, are 
 intimately associated with those diseases spread by the agency of 
 water, such as enteric fever, cholera, dysentery, etc. The chemical 
 action which takes place is probably due to the presence of a 
 nitrifying ferment in the sand as well as to air in the interstices 
 of the sand itself; this action is not, however, regarded as being 
 of much importance. The mechanical action which frees the 
 water from micro-organisms is largely assisted by the deposit of 
 slime on the surface of the niters, and it is now recognized that in 
 sand we possess a most powerful medium for removing germs from 
 water. Two conditions are, however, necessary to obtain the best 
 results ; these are (1) that the sand should be of a certain thick- 
 ness, not less than 30 cm. (1 foot), and (2) that the water should 
 not flow through it at a greater pace than 4 inches in one hour, 
 or 50 gallons daily per square foot of surface. The action of this 
 filter is partly mechanical, partly vital ; the mechanical action is 
 confined to the holding back of the grosser substances which have 
 not subsided, but remain suspended in the water; the vital 
 action consists in the layer deposited on the surface of the sand 
 which is charged with microbian life, and it is by these organisms, 
 which are constantly increasing in number, and which penetrate 
 the sand to a slight distance, that both the nitrification of organic 
 matter and the arrest of other microbes is effected. From this it 
 is evident that in order to preserve the power of these filters, the 
 surface layer should not be removed so long as water passes 
 through it. Roughly stated, it may be said that a filter becomes 
 " dead " {i.e. nearly impervious to water), and consequently demands 
 cleaning once every three or four weeks in summer, and about 
 half as frequently in winter; but it is not possible to lay down 
 hard and fast general rules applicable to all filters. In some 
 experiments recently undertaken in America, to test the power of 
 sand filters in removing pathogenic bacteria, and especially that 
 associated with typhoid fever from drinking water, it was found 
 that 99 J per cent, of the applied bacteria were removed, and this 
 goes to prove that these filters act efficiently when properly con- 
 structed as a safeguard against water-borne diseases." The rate of 
 flow through the filter must not exceed 4 inches in one hour, 
 
j6 WATER. 
 
 and the rule should be that no water can be regarded as efficiently 
 filtered that contains more than ioo micro-organisms in i c.c. of the 
 filtered water. But cases will arise in which it is necessary to purify 
 water, and when no regular system of filtration as above described 
 exists or is possible, simpler and often ruder methods are all that 
 can be devised. 
 
 Owing to their relatively slow rate of filtration, the gravity 
 sand and gravel filter-beds have been subjected to some criticism. 
 As an outcome of this criticism, installations have been devised 
 in which the water receives from ^th to i grain of sulphate of 
 alumina per gallon ; this serves as an adjuvant to the filter for the 
 holding back of micro-organisms and fine suspended matter in 
 the water. Filters of this kind have the sand contained in steel 
 drums, and the water is passed through under pressure; 600 
 square feet of filter surface purifying satisfactorily a million gallons 
 of water daily. An efficient representative of this type is the Bell 
 Patent Filter. Another kind of filter is that known as the Candy 
 filter. In this system no chemical coagulants are used ; the water 
 to be purified is first saturated with air, forced in under pressure, 
 and then strained by passing it through sand contained in cylin- 
 drical chambers or drums. This procedure is very successful in 
 removing iron and lead from waters, while the degree of bacterial 
 purification is stated to average 93 per cent. 
 
 Apart from the above methods, successful purification of water 
 on a large scale can be secured by chlorination. This is done by 
 the addition of bleaching powder or a solution of hypochlorite of 
 calcium, sodium, or magnesium, so that there is maintained in the 
 water 1 part per million of available chlorine for half an hour. 
 The carbonic acid naturally present in the water liberates hypo- 
 chlorous acid from the hypochlorite of calcium or other salt used. 
 The bleaching powder is changed into harmless calcium carbonate 
 and calcium chloride. The amount necessary to be added can be 
 determined by testing for free chlorine by means of potassium 
 iodide and starch fifteen minutes after the addition of the chlori- 
 nated lime. If a blue colour appears when the chlorinated water 
 is mixed with the iodide and starch, some free chlorine is present 
 and it is unnecessary to add more of the chlorinated lime. If no 
 blue colour appears there is still need for free chlorine, and more 
 of the chlorinated lime must be added and the test repeated. 
 
 In a permanent chlorination installation it is necessary to 
 remove the residual chlorine before it enters the mains. This 
 can be done by means of bisulphite of soda, but more generally 
 by passing the sterilized water through filters of vegetable char- 
 coal, which remove all odour and taste from the chlorinated 
 water. The chlorination process is less costly than sand filtration 
 
PURIFICATION OF WATER. 
 
 77 
 
 and equally efficient. It is particularly suitable for river waters 
 used as a source of supply. This chlorination process has been 
 much used in the army during the great war and lis coming into 
 use among civil communities. Other methods, such as ozonisation 
 and treatment of water by ultra-violet rays of light, have been 
 suggested for water purification ; as yet they have not reached 
 the economically practical stage. 
 
 The foregoing methods are all designed for dealing with water 
 in considerable quantities. Although it is customary for water 
 supplied by public companies to be sufficiently purified before 
 distribution, yet circumstances exist in which domestic filtration 
 is often a necessity. Among the number of substances suggested 
 or used for this purpose, animal charcoal, either in granules or 
 made into silicated blocks, has long been very popular. Modern 
 experience shows that, although charcoal possesses considerable 
 oxidizing powers on the organic impurities dissolved in water, it 
 does not sterilize it, but, on the contrary, permits micro-organisms 
 to pass through unchanged. The suspended matters tend to 
 deposit on it, forming a slime on the surface, which contaminates 
 the water it is supposed to purify. A filter which depends on a 
 block of carbon alone is useless for the purposes of filtration. 
 
 Recent investigations go to show that the value of any 
 filter does not so much depend on its action 
 on the chemical constituents of a water supply 
 as on its power of holding back micro-organisms, 
 which are now generally admitted as being 
 closely connected with the specific diseases. 
 
 Judged by this standard, the only materials 
 suited for filtration work are certain infusorial 
 earths, clays, porcelain, or patent combinations 
 of porcelain with clay. The best modern 
 domestic filters are those made of judicious 
 mixtures of selected clays : these are moulded 
 into tubes or bougies, enclosed in metal jackets, 
 and the water forced through them under 
 pressure, varying from 20 to 40 lbs. on the 
 square inch. The usual type of these filters 
 is shown in Fig. 16, where the filtering tube 
 is attached to an ordinary tap and the water 
 forced through the medium by the pressure of 
 the water in the main. In the portable or 
 detachable types, the water is placed under 
 pressure by means of an attached pump and 
 so forced through the filter. 
 
 These filters act on water precisely as sand filters act on a 
 large scale : they sterilize the water — that is, the pores are so 
 
 Fig. t6 — Tube-filter 
 fitted to tap. 
 
?S WATER. 
 
 small and the current of water so finely divided that micro- 
 organisms are unable to pass through. The niters have no action 
 on the dissolved organic impurities in water, but it is of no less 
 importance that water intended for drinking purposes should be 
 free from these, as with such, no doubt, is associated the multi- 
 plication of micro-organisms, if not their virility and potency. 
 
 The rate of nitration through these niters depends mainly on 
 the pressure of the water, which passes from without inwards. 
 This is convenient, as the deposit, which tends to be and is 
 gradually formed on the outer surface during use, can be easily 
 washed or brushed off on removing the screw-tap. Although these 
 " bougies," or candles, deliver sterile filtrates for a considerable 
 time, often when left uncleaned, it must be remembered that 
 they cannot do so indefinitely. Experiments have shown that, 
 when immersed in foul or polluted water, these filters, particularly 
 those whose lacunar spaces are large, permit of the growth of 
 pathogenic bacteria through their substance, and ultimately fail 
 to yield sterile filtrates. This growth of bacteria through these 
 filters may take place in as short a period as four days, hence the 
 necessity, especially when foul water has been subjected to filtra- 
 tion, of sterilizing the filters every three days by careful immersion 
 and scrubbing of their surfaces in boiling water. The only bougies 
 which have failed to permit of bacterial growth through their 
 interstices are the tubes or candles made of porcelain or clays of 
 very close texture. They, though certainly more reliable, deliver 
 water much more slowly than others of a more open texture. 
 
 For the purification of water by heat there are three methods ; 
 these are distillation, boiling, and the employment of special 
 apparatus working on the heat exchange principle. 
 
 Distillation is employed rarely on land, its applicability is 
 limited practically to shipboard and to a few places abroad de- 
 pendent upon sources of supply which are not only organically 
 impure but also brackish. The final product is often flat and 
 dull owing to loss of dissolved gases ; one of the greatest of 
 objections to distilled water is its indifferent storage qualities 
 particularly in hot countries. 
 
 Boiling is limited to the purification of water in small quantities, 
 and though ensuring the destruction of micro-organisms, presents 
 the objection of being extravagant in fuel, makes the water flat 
 and insipid, and leaves the finished article hot and of limited 
 utility. 
 
 To overcome this last objection various special apparatus 
 designed on the heat exchange principle have been invented. 
 These sterilizers utilize the fact that, with a sufficient area of 
 metallic surface of good conducting capacity and sufficient time, 
 
WATER ANALYSIS. 79 
 
 a given quantity of hot liquid will yield nearly all its heat to an 
 equal amount of similar but cold liquid. By adopting this 
 principle large quantities of water can be rapidly treated and as 
 rapidly cooled with the result that a volume of water is sterilized 
 quickly, retains its dissolved gases, issues from the apparatus 
 nearly as cold as it went in, and with the expenditure of a small 
 quantity of fuel. The majority of apparatus designed on this 
 principle bring the water to the boil and depend upon the ex- 
 pansion of the boiling water for the maintenance of a circulation 
 of the liquid through the machine. For the actual sterilization of 
 water ebullition is unnecessary, it being sufficient to maintain the 
 water at 180 F. for a few seconds to secure the destruction of 
 the disease-producing micro-organisms usually found in water. 
 In apparatus designed on this fact, it is essential to employ some 
 form of valve or thermostat to control the flow of water, or rather 
 not to permit of the passage of water over to the cooler unless it 
 has been maintained at 180 F. for the requisite period of time. 
 Except for isolated houses dependent on an impure supply of 
 water, we question whether there is much scope for these 
 methods. The same remark applies to certain chemical methods 
 for sterilizing water on a small scale, such as the use of alum, 
 permanganate of potassium, iodine, or bisulphate of sodium. 
 They are essentially academic methods, and in the hands of 
 unscientific people likely to do more harm than good. 
 
 Water Analysis. 
 
 The results of a sanitary analysis of water must be considered 
 in connection with many conditions, such as the locality and 
 surroundings of the water, the depth or rate of flow of the river 
 or lake, the season of the year, the conditions of the catchment 
 area, etc. ; if wells, their proximity to the sea, their depth, and, if 
 possible, the strata through which they pass. Conditions such 
 as these largely affect the interpretation of the results which a 
 chemical analysis of a water gives. For example, the limit of free- 
 ammonia and chlorine allowed in a water taken from a deep well 
 of 800 or 900 feet, would, if present in a surface well of 20 or 30 
 feet in depth, indicate contamination of a serious kind. The 
 object of an analysis of water is to determine the amount of 
 mineral and organic constituents, and to note for future examina- 
 tion the character of the suspended matters. 
 
 At the outset, a knowledge of the source of the water is 
 necessary, whether a surface water or ground water. A surface 
 water nearly always contains animal and vegetable life, while 
 water from the deeper strata is usually devoid of life until it is 
 
SO WATER. 
 
 exposed to the action of light and air in reservoirs, under which con- 
 ditions it assumes in this respect the characters of a surface water. 
 
 Collection of Samples. — In order to secure that the results of 
 an examination of water should be of value, care must be exer- 
 cised in the collection of the samples. Winchester quart bottles, 
 holding half a gallon, are very suitable for the purpose ; the bottle 
 used should be carefully cleansed with a little hydrochloric or 
 sulphuric acid, and then thoroughly washed out with pure dis- 
 tilled water or some of the water to be examined. When a sample 
 is taken, the bottle should be filled quite full, and just sufficient 
 poured off so that a little air-space is left under the stopper, care 
 being taken that the inside of the neck of the bottle or the stem 
 of the stopper be replaced untouched by the hand or wiped with 
 a cloth. Corks should not be used except in great emergency, 
 and then only if they are quite new and thoroughly rinsed in 
 water before being used. No luting of wax plaster or similar 
 material should be used. 
 
 In taking samples from streams, lakes, or reservoirs, the 
 bottle should be submerged with its stopper in the water, and 
 the stopper withdrawn 12 inches or more below the surface, so 
 as to avoid collecting any of the water that has been in immediate 
 contact with the air. If from a public water supply, the sample 
 should be drawn from a hydrant in direct connection with the 
 main, and not from a cistern or storage tank; if taken from a 
 service pipe, the water should be allowed to run to waste for 
 some minutes before it is collected, in order to remove that 
 which has been standing in the pipe ; the bottle should then be 
 rinsed out at least three times, pouring out the water completely 
 each time; the same practice should be adopted in the case 
 of pumps. Water should be examined as soon after collection 
 as possible, and kept in a cool place not exposed to light. 
 
 It is important that with each sample the fullest information 
 should be given of those conditions and surroundings which may 
 influence the character of the water; especially must be noted 
 the source of the water, whether from wells, rivers, cisterns, 
 public supplies, etc. If a well, the depth and the depth of 
 water in the well, whether steined or otherwise, the strata through 
 which it is sunk, the position and distance as regards cesspools, 
 privies, drains, etc., whether the land around is cultivated, whether 
 a pump is attached, and if not, how the water is raised. If 
 a cistern, how supplied ; if by rain, the nature of the collecting 
 surface and storage. If a public water supply, the source, and 
 whether the water is supplied on the constant or intermittent 
 system. It should also be stated whether any disease is suspected 
 to have been caused by the water, so that a bacteriological exami- 
 
 
WATER ANALYSIS. 8l 
 
 nation may be made if considered necessary. No point likely to 
 afford information should be omitted. 
 
 Physical Examination of Water. — Water should be clear and 
 free from turbidity. Turbidity is caused ' by the suspended 
 matters in water, that which on standing for some hours settles to 
 the bottom is its sediment. As a rule, surface waters are turbid, 
 deep-well waters clear ; the suspended particles may be finely 
 divided clay, algae or some other living form, animal or vegetable. 
 The colour of water may be judged by looking through a stratum 
 of water 12 inches deep; this can be done by using a tall glass 
 placed on a sheet of white paper. Pure water is generally of a 
 bluish or greyish colour. Yellow or brown waters are suspicious, 
 as they frequently owe their colour to sewage, unless in peat 
 districts or in places where iron is found, in which case the waters 
 are not usually hurtful. The taste of water is a most uncertain 
 guide ; the taste depends almost altogether on the gases dissolved 
 in the water, and not upon the soluble animal and mineral matters, 
 unless these are in large excess. Any badly tasting water should 
 be rejected. Taste also differs much in different persons. Common 
 salt can only be tasted when 75 grains are added to 1 gallon of 
 distilled water, and the other mineral constituents usually present 
 must be large before they can be recognized. Iron is the only 
 substance which can be tasted in small quantities. 
 
 The odour of water is best detected by heating it in a stop- 
 pered flask to 8o° F. As a rule, the odour only lasts for a few 
 moments, and should be judged by removing the stopper and 
 smelling the water at once ; it is sometimes a guide in polluted 
 waters, and gives a clue to the origin of the pollution. Any 
 offensive smell is sufficient to condemn a water. 
 
 The physical characters of a pure and wholesome water are 
 freedom from any marked colour and from suspended matters, a 
 brilliant lustre, devoid of any taste or smell. In a large majority of 
 cases, water possessing these characters is fit for drinking purposes. 
 
 It is not intended in this manual to treat fully the subject of 
 water analysis, which requires much elaborate apparatus and 
 considerable chemical knowledge, but a few qualitative and 
 quantitative tests are given, capable of indicating the general 
 characters of a water. 
 
 Qualitative Examination of Water. — The realtio?i of pure 
 water is usually neutral. If acid and the acidity disappears on 
 boiling, it is due to carbon dioxide. If alkaline and the alkalinity 
 disappears on boiling, to ammonia. If permanently alkaline, it is 
 probably from sodium carbonate. 
 
 Litmus and turmeric papers are used to determine the 
 reaction, which is usually red or yellow if acidity be present. 
 
82 WATER. 
 
 Hardness. — Add oxalate of ammonium ; if calcium is present, 
 a white precipitate is formed : 6 grs. per gallon gives turbidity, 
 1 6 grs. a considerable precipitate. 
 
 Chlorides, with nitrate of silver and dilute nitric acid, give a 
 white precipitate : i gr. per gallon gives a haze, 4 grs. per gallon 
 gives a marked turbidity, and 10 grs. a considerable precipitate. 
 
 Nitrates. — Add a solution of brucine (1 grm. in 1 litre of 
 distilled water) and strong sulphuric acid. The sulphuric acid 
 should be poured gently down the sides of the test tube to form 
 a layer under equal parts of a mixed water and brucine solution. 
 Half a grain of nitric acid per gallon gives a marked pink-and- 
 yellow zone ; or 2 c.c. of the water may be evaporated to dryness 
 and a drop of strong sulphuric acid and a minute crystal of brucine 
 dropped in — o*oi gr. per gallon can be easily detected. 
 
 Nitrites. — Nitrous acid decomposes iodide of potassium, and 
 free iodine gives a blue colour with starch. Boil 20 grms. of 
 starch intimately mixed with half a litre of distilled water ; filter 
 when cold, and add 1 grm. of potassium iodide. If a little of 
 this solution is mixed with the water to be examined, and dilute 
 sulphuric acid added, an immediate blue colour will appear, 
 should nitrites be present; or Griess's test may be employed. 
 To 100 c.c. of the water add 1 c.c. of metaphenylenediamine 
 solution (made by dissolving 5 grms. of metaphenylenediamine 
 in 1 litre of distilled water, rendered acid with sulphuric acid, and 
 decolourized, if necessary, with animal charcoal) and 1 c.c. of 
 dilute sulphuric acid (1 in 3). A yellow colour, changing to red, 
 will appear in the water in half an hour if there be only one part 
 of nitrous acid in ten millions of water. 
 
 Ammotiia is detected by Nessler's solution ; if present in water, 
 a yellow colour or yellow-brown precipitate is formed. If in 
 small quantity the colour should be observed through a column 
 of water 4 or 5 inches in depth, the glass being placed on a white 
 ground. 
 
 Iron. — Ferrocyanide of potassium (yellow prussiate) gives a 
 blue colour with ferric salts, and ferricyanide (red prussiate) with 
 ferrous salts. The water should be rendered acid with dilute 
 hydrochloric acid, free from iron. A comparative test should be 
 made with distilled water. 
 
 Lead or Copper. — Place some water (100 c.c.) in a white 
 dish, and stir with a rod dipped in ammonium sulphide ; wait till 
 colour is produced, then add a drop or two of hydrochloric acid. 
 If the colour disappears, it is due to iron; if not, to lead or 
 copper. 
 
 The following test is best applied to water concentrated to 
 one- fiftieth part of its original volume : — 
 
WATER ANALYSIS. 
 
 83 
 
 Magnesia. — Add oxalate of ammonium to precipitate the lime, 
 then after nitration a few drops of phosphate of sodium, of chloride 
 of ammonium, and of liquor ammonias. A white crystalline 
 precipitate of magnesium-ammonium phosphate appears within 
 twenty-four hours. 
 
 The Quantitative Analysis of Water. 
 
 The chief points which require determination in an ordinary 
 quantitative analysis are the total solids, the chlorides, the hard- 
 ness, and the organic matter as represented by what are called 
 the free and albuminoid ammonia. If additional evidence as to 
 the quality of the water is required, to these may be added the 
 determination of the amount of oxygen absorbed, and the amount 
 of nitrogen existing as nitrites and nitrates. 
 
 The main principle of a quantitative, or volumetric analysis, 
 is the submission of the substance to be estimated to certain 
 characteristic reactions, employing for such reactions solutions 
 of known strength; and from the volume of solution necessary 
 for the production of the reaction, determining the weight of the 
 substance to be estimated by the application of the known laws 
 of chemical equivalence. 
 
 To carry out any quantitative analysis, the first essential is 
 the thorough comprehension of the simple relationship between 
 liquids and solids. Owing to its uniformity and simplicity, in 
 the following analytical methods, the metric system alone will be 
 mentioned. Although tables of the various metric weights and 
 measures are given in the Appendix, it may not be out of place 
 here to emphasize the fact that a cube of distilled water at its 
 greatest density, viz. 4° C, or 39 F., whose side measures 1 
 decimetre, has exactly the weight of 1 kilogramme, or 1000 
 grammes, and occupies the volume of 1 litre, or 1000 cubic 
 centimetres. In other words, 1 cubic centimetre, as a measure 
 of volume, equals or corresponds to 1 gramme as a measure of 
 weight, and that 
 
 Grammes of a subst. diss, in 10 c.c. of water are .# parts in 
 
 >> 
 
 i) 
 
 Decigrammes 
 
 Centigrammes 
 
 Milligrammes 
 
 5) 
 
 11 
 
 Jj 
 
 JJ 
 
 JJ 
 
 JJ 
 
 5J 
 
 5J 
 
 JJ 
 
 J) 
 
 >» 
 
 JJ 
 
 JJ 
 
 59 
 
 JJ 
 
 >J 
 
 }> 
 
 JJ 
 
 )) 
 
 IOO 
 IOOO 
 
 JJ 
 J> 
 JJ 
 
 IOO 
 
 10 
 
 J> 
 
 n 
 
 11 
 
 11 
 
 »J 
 
 JJ 
 
 )) 
 
 5J 
 
 JJ 
 
 (1 litre) 
 (1 litre) 
 (1 litre) 
 (1 litre) 
 of water 
 
 >> 
 
 )> 
 
 )> 
 
 11 
 
 53 
 
 11 
 
 11 
 
 11 
 
 11 
 
 11 
 
 X 
 X 
 X 
 X 
 
 X 
 X 
 X 
 X 
 
 JJ 
 
 JJ 
 
 JJ 
 
 JJ 
 
 JJ 
 
 JJ 
 
 JJ 
 
 J} 
 
 TO 
 IOO 
 
 1,000 
 
 10,000 
 
 100,000 
 
 1,000,000 
 
 100,000 
 
 10,000 
 
 1,000 
 
 It is most usual, in this country and on the Continent, to 
 
84 WATER. 
 
 express the results of a quantitative analysis as parts per 100,000 
 — that is, centigrammes per litre, or milligrammes per 100 cubic 
 centimetres. This ratio will be adopted in the following analytical 
 processes, while, for the sake of brevity, the term (C cubic centi- 
 metre " has been written as c.c. 
 
 Occasionally, the expression grains per gallon is met with in 
 English analysis. This is equivalent to parts per 70,000, as 
 there are 70,000 grains in a gallon. The conversion of parts 
 per 100,000 to grains per gallon is, of course, readily performed 
 by multiplying by y^, or by 07 ; and from grains per gallon to 
 parts per 100,000, by multiplying by 10 and dividing by 7 
 
 Tne Apparatus specially needed for making a Quantitative 
 Analysis consists of — 
 
 1. A pair of balances, and weights according to the metric 
 system. In these sets of weights, the larger ones represent 
 grammes, the next in size decigrammes, and the next centi- 
 grammes. Small forceps are used for picking up and applying 
 these weights to the pans of the balance. The milligrammes 
 are added by shifting a little piece of bent wire along the cross- 
 beam of the balance, which has on it ten markings, numbered 
 from 1 to 10, on either side of the pivot. 
 
 2. A platinum dish, capable of holding 200 c.c. of water. 
 
 3. One or more shallow porcelain evaporating dishes, capable 
 of holding 300 c.c. 
 
 4. A small porcelain crucible, with lid, for igniting residues. 
 
 5. A pestle and mortar, for powdering reagents previous to 
 solution. 
 
 6. One or more retorts, or boiling flasks. 
 
 7. A Graham's, or Liebig's condenser. 
 
 8. Six Nessler Glasses, each capable of holding 100 c.c. 
 
 9. Glass stirring-rods. 
 
 10. Two glass-stoppered bottles, capable of holding 250 c.c. 
 
 11. Glass funnels for filtering. 
 
 12. A packet of Swedish f Iter papers. 
 
 13. A dozen test tubes, with stand, cleaner, and holder. 
 
 14. A measuring flask, to hold at least 1 litre and graduated 
 in cubic centimetres. 
 
 15. Glass burettes, or graduated tubes, holding 50 c.c, and 
 graduated in cubic centimetres and tenths of a. cubic centimetre. 
 One of these should be mounted on a wooden stand, and be pro- 
 vided with a stopper at the top, and fitted with a stop-cock at the 
 bottom. 
 
 16. Glass pipettes, graduated to deliver 10, 20, 50, or 100 c.c. 
 
 17. An iron tripod. 
 
 18. One or more triangles of iron wire, covered with pipeclay. 
 
WATER ANALYSIS. 8$ 
 
 19. A pair of small crucible tongs. 
 
 20. A long thermometer, graduated in either Centigrade or 
 Fahrenheit degrees. 
 
 Standard Solutions required in a quantitative analysis, are 
 solutions of definite strength, made by dissolving a given weight 
 of a reagent, in grammes, in a definite volume of distilled water 
 in cubic centimetres. These solutions are usually made by 
 dissolving either the hydrogen equivalent weight of a reagent in 
 grammes, or some decimal part of such weight in 1000 c.c. (1 litre) 
 of water. The following abbreviations are often used to express 
 the strength of these solutions : — 
 
 N = a normal solution having hydrogen equivalent weight in 
 N ! grammes per litre 
 
 »> 2 " " " 
 
 a semi-norma. 
 
 — = a deci-normal 
 
 10 " 10 
 
 N ... . 1 
 
 — = a viginti-normal ,, — 
 
 20 20 
 — = a centi-normal 
 
 SJ )> M 
 
 » " JJ J) ?) 
 
 IOO IOO 
 
 = a milli-normal ,, — L 
 
 1000 1000 
 
 53 j> i) 
 
 In place of using the above normal or deci-normal solutions, 
 it is often found convenient to use what may be called a 
 standard solution — that is, a solution of a reagent so made that 
 a cubic centimetre has a value expressible as unity or some con- 
 venient figure or factor. Thus, an empirical standard solution 
 of silver nitrate can be made to the strength that 1 c.c. is 
 capable of precipitating 1 mgm. of chlorine. This is made by 
 dissolving, not the hydrogen equivalent weight of silver nitrate, 
 but that fractional part of it which is equal to one of chlorine. 
 Taking AgN0 3 to be represented by 170, in terms of its hydrogen 
 equivalent weight, and chlorine as 35*5, then 4*788 grms. of the 
 silver nitrate dissolved in a litre of distilled water, would give a 
 solution, a cubic centimetre of which would exactly equal 1 mgm. 
 of chlorine. 
 
 Occasionally, in making standard solutions the equivalent 
 hydrogen weight of a reagent cannot be taken, but its particular 
 weight in a particular reaction in a given analysis has to be 
 regarded. For instance, when using a solution of potassium per- 
 manganate, as an oxidizing agent, having the chemical formula 
 KMn0 4 , and the molecular weight of 158, and yielding five 
 atoms of oxygen in a particular reaction, its normal solution is 
 
86 WATER. 
 
 made by dissolving one-fifth of its molecular weight, ~, or 31*6 
 grms. in a litre of water. In other instances, when the hydrogen 
 equivalent weight of a substance is not identical with the atomic or 
 molecular weight, the amount taken is the equivalent weight. Thus, 
 oxalic acid, C 2 H 2 4 2H 2 0, (with an atomic weight of 126, is a 
 dibasic substance, and its equivalent weight is one-half of its 
 molecular weight ; consequently, a normal solution of oxalic acid 
 would be made by dissolving 6$ grms. of the crystallized acid 
 in 1 litre of distilled water. Similarly phosphoric acid, which is 
 a tribasic substance, would require, for the preparation of a 
 normal solution of sodium phosphate, Na 2 HP0 4 i2H 2 0, one-third 
 of its molecular weight ^f-, or 1193 grms. being dissolved in 
 distilled water and made up to 1 litre. 
 
 Indicators. — In order to enable us to ascertain, by a change 
 of colour or other marked effect, the exact point at which a 
 given reaction is complete, certain substances, called indicators, 
 are employed. The chief are as follows : — 
 
 (a) Solution of litmus^ which turns red with acids and blue 
 with alkalies. 
 
 (b) Alcoholic solution of phetiol-phthalein, which is colourless 
 with acids, but becomes red with alkalies. 
 
 (c) Starch mucilage^ which turns blue in the presence of free 
 iodine. 
 
 (d) Solution of potassium chromate, which gives a red with 
 nitrate of silver, but not until all the chlorine or halogen present 
 has entirely combined with the silver. 
 
 Estimation of Total Solids in a Water Sample. 
 
 The estimation of the total solids, by itself, is not of very 
 great practical hygienic value, but affords a control over the other 
 quantitative determinations. Take 250 c.c. of the water sample, 
 place in an evaporating dish, and slowly evaporate down to 100 
 ex., or less, carefully guarding against any of the solids remain- 
 ing attached to the sides of the dish. Transfer the concentrated 
 water and residue to either a small, clean, weighed crucible, or 
 platinum dish. Evaporate to complete dryness, in air, water, or 
 steam bath, at 105 C. So soon as the capsule is cold, reweigh : 
 the difference in weight will be the amount of total solids. A 
 simple form of steam bath can be made by taking a common two- 
 gallon tin can, fitting a perforated cork into its mouth, and passing 
 a funnel through the perforation. The crucible is placed in the 
 funnel, water boiled in the tin can, and a little roll of paper placed 
 between the funnel and the crucible to let the steam pass out. 
 
WATER ANALYSIS. 87 
 
 Example. — Total solids, 250 c.c, dried as described — ■ 
 
 Grammes. 
 
 Weight of dish and residue . 23*14 
 
 ,, „ alone 23-09 
 
 Difference being total solids in \ litre of water . . . 0*05 
 or 0*05 part in 250. 
 
 This multiplied by 400 or 0*05 X 400 = 20 parts of total solids 
 in 100,000. 
 
 After the total solids have been determined, they should be 
 slowly incinerated over a flame to dull redness, when any organic 
 matter will give evidence of its presence by charring or by yielding 
 dark fumes with the smell of burnt horn. Continue the incinera- 
 tion until nothing remains but a clear white mineral ash. If iron 
 be present, the ash may be red ; whilst manganese gives it a 
 greenish tint. Having allowed the capsule to cool, weigh again ; 
 the excess weight now over that of the clean and empty dish 
 represents the fixed solids, and the difference between them and 
 the total solids gives the volatile solids. 
 
 Fixed Solids. — The above residue is incinerated as described. 
 
 Grammes. 
 Weight of incinerated residue and dish . 20*12 
 
 ,, dish alone 20*09 
 
 Difference being fixed solids in \ litre of the water . 0*03 
 
 This multiplied by 400 or 0*03 X 400 = 12 parts of fixed solids 
 in 100,000. 
 
 Volatile Solids. 
 
 Total solids ......... 20 parts per 100,000 
 
 Fixed ,, 12 ,, ,, 
 
 Difference being volatile solids ... 8 
 
 »> 
 
 The total solids consist in most water samples of carbonates 
 of calcium, sodium, magnesium, potassium, and iron ; sulphates 
 and chlorides of sodium, calcium, and magnesium ; nitrites and 
 nitrates of calcium, sodium, and potassium ; with occasionally 
 some phosphates of potassium and sodium. 
 
 The volatile solids consist generally of ammonium salts, 
 nitrites, nitrates, some of the chlorides and carbonates, with water 
 from sulphate of lime and destructible organic matter. 
 
 The amounts of total solids vary from 3 or 4 to 50 or 60 
 parts per 100,000. Of these not more than 3*0 per 100,000 
 should be volatile or lost on ignition. 
 
88 WATER. 
 
 Estimation of Chlorides in a Water Sample. 
 
 For this purpose two solutions are required. 
 
 (i) A solution of Potassium Chromate, made by dissolving 
 50 grms. of the salt in a litre of distilled water. Nitrate of 
 silver is added until a permanent red precipitate is formed, which 
 is allowed to settle and the clear liquid decanted off. 
 
 (2) A deci-normal standard solution of Silver Nitrate, made by 
 dissolving 17 grms. of AgN0 3 (molecular weight being 170) 
 in a litre of distilled water. This will be equivalent to one-tenth 
 of the atomic weight of chlorine (35*5), or 3*55 grms. of chlorine, 
 and 1 c.c. of this solution will equal 3*55 mgms. of chlorine. 
 
 The process consists in taking 250 c.c. of the water sample, 
 
 placing them in a white porcelain dish, and rendering them of a 
 
 distinct yellow colour by means of two or more drops of the 
 
 potassium chromate solution. From a burette, run in drop by 
 
 N 
 drop some of the — silver nitrate solution, stirring after each 
 
 IO in 
 
 addition. The red silver chromate which is at first formed will 
 disappear as long as any chlorine is present. Stop directly the 
 least red tint is permanent. As each cubic centimetre of the 
 silver solution equals 3*55 mgms. of chlorine, the number of cubic 
 centimetres used indicates the milligrammes of chlorine in 250 c.c. 
 of the water — that is, parts per 250,000 — and that divided by 2*5 
 or multiplied by 04 will give parts of chlorine for 100,000. 
 
 Example. — In 250 c.c. of water, rendered yellow with potassium 
 chromate, 1*5 c.c. of silver solution gave a permanent red tint; 
 then — 
 
 ; = 2 - i3 parts of chlorine per 100,000 
 
 2 5 
 
 The purest water, as a rule, contains less than 1*5 parts of chlorine 
 per 100,000. An increase may be due to sea water, to percolation 
 through salt-bearing strata, to sewage or other impurities. Some 
 deep wells often contain large quantities of chlorides ; but gene- 
 rally an excessive presence of chlorides is a reason for suspicion 
 unless a satisfactory explanation of their presence is obtainable. 
 
 Estimation of Hardness in a Water Sample. 
 
 The hardness of a water is' conveniently determined by means 
 of the soap test. Soap is the oleate of an alkali metal resulting 
 from the combination of an alkali metal with one or more of 
 the fatty acids, i.e. oleic, stearic, or palmitic acids. When an 
 
WATER ANALYSIS. 89 
 
 alkaline oleate is mixed with pure water a lather is given almost 
 immediately, but if salts of calcium, magnesium, aluminium, 
 barium and iron, or other similar substances are present in the 
 water the soap forms oleates with these bases, and no lather is 
 formed until these earthy bases are thrown down or used up. 
 The hardness of a water depends upon the presence in it of more 
 or less of these earthy bases, and the more they are present the 
 greater will be the expenditure of soap to make a lather. Free 
 carbon dioxide has a similar effect. The soap combines in 
 equivalent proportions with these bases, so that if a solution of 
 soap be graduated by a solution of known strength of any one of 
 them, it will be of equivalent strength for corresponding solutions 
 of any of the others. Owing to magnesia having a tendency to 
 form double salts with the fatty acids, the results are not quite so 
 accurate as for calcium or barium. A certain amount of the hard- 
 ness of a water is removed by boiling, hence it is usual to speak of 
 the hardness present before boiling as total hardness, that remain- 
 ing after boiling as fixed or permanent hardness, and that which 
 has been dissipated by the boiling as the temporary hardness. 
 
 The total hardness in most drinking waters is caused by salts 
 of calcium and magnesium with some free carbon dioxide. Hence 
 waters from the chalk, oolite, limestone, dolomite, and new red sand- 
 stone are apt to furnish the greatest degrees of hardness. Rain 
 water, being free from these salts, is usually very soft. Many of 
 the salts contributing to the total hardness are held in solution 
 by carbon dioxide, and when the water is boiled this is dissipated, 
 causing these salts to fall to the bottom or form incrustations on 
 the sides of the containing vessel as insoluble salts. The chief of 
 these are carbonates and sulphates of calcium and magnesium, 
 with silicates of iron and aluminium when these are present. 
 
 The permanent hardness, or what still remains in solution, 
 consists mainly of some sulphates, chlorides, and nitrates of 
 calcium and magnesium, with a little iron and aluminum. 
 
 The Soap solution for the estimation of hardness is best made 
 by thoroughly dissolving by stirring and warming some soft soap 
 in a mixture of 4 parts methylated spirits to 6 of distilled water, 
 and then filtering. This solution of soap should be standardized — 
 that is, diluted or strengthened as the case may be, so that 2*2 
 c.c. of it exactly give a permanent lather when shaken up with 
 50 c.c. of a solution of nitrate of barium. Barium nitrate Ba(N0 3 ) 2 
 has a molecular weight ratio to calcium carbonate CaC0 3 , of as 
 261 is to 100, and if 0*261 grm. of barium nitrate be dissolved in 
 a litre of distilled water, that solution equals o*i grm. of calcium 
 carbonate, and 50 c.c. of the same solution equals 5 mgms. of 
 calcium carbonate. Now, if the soap solution be so made that 
 
90 
 
 WATER. 
 
 2*2 c.c. of it give a lather with 50 c.c. of the above barium nitrate 
 solution, after deducting o'2 c.c. for the amount of soap solution 
 necessary to give a lather with 50 c.c. of distilled water, we get 
 2 c.c. of the soap solution to equal 50 c.c. of a barium nitrate 
 solution, which again is equivalent to 5 mgms. of calcium car- 
 bonate, hence each cubic centimetre of the soap solution equals 2*5 
 mgms. of calcium carbonate. Say, for instance, a small quantity of 
 soap solution of unknown strength has been made, and on its being 
 standardized with 50 c.c. of the barium nitrate solution, it is found 
 that 1 c.c. gives a lather in place of 2*2 c.c. being so required. 
 The soap solution measures 30 c.c. Then as 1 : 2 '2 : : 30 : x 
 = 66 ; that is, the 30 c.c. must be diluted up to 66 c.c. to give 
 a soap solution, of which 1 c.c. shall exactly equal 2*5 mgms. of 
 calcium carbonate. Of course, if the soap solution be found too 
 weak it must be proportionately fortified with more soap until 
 2*2 c.c. exactly give a lather with 50 c.c. of the 0*261 Barium 
 nitrate solution. 
 
 To determine the Total Hardness, take 50 c.c. of the sample 
 and place in a stoppered shaking-bottle. From a burette run in 
 sufficient of the soap solution, until on being briskly shaken the 
 contents of the bottle give only a faint dull sound with the forma- 
 tion of -j inch of fine uniform lather. This lather should show an 
 unbroken surface after standing 5 minutes. 
 
 Suppose the addition of 2*4 c.c. of the soap solution have 
 produced the necessary sound and lather. Deducting o'2 c.c. as 
 being necessary for the production of a lather in 50 c.c. of the 
 purest water, we get 2*2 c.c. of the soap solution required by 
 50 c.c. of the water sample or 4*4 necessary for 100 c.c. Each 
 of these cubic centimetres equals 2*5 mgms. of calcium carbonate ; 
 hence 4*4 X 2*5 = 11 mgms. of calcium carbonate in 100 c.c. of 
 the water, representing a total hardness of n parts per 100,000 — 
 that is, 1 1° of hardness on the metrical scale. The original intro- 
 ducer of this soap test, Dr. Clark, used to express the hardness 
 as so many grains per gallon, hence n° on the metrical scale are 
 the same as 7*7° on Clark's scale, or n x 07 = 77 grs. of calcium 
 carbonate per gallon. 
 
 When the total hardness exceeds 20 parts per 100,000, an 
 over-estimation may be made as the excess of calcium and mag- 
 nesium interfere with the formation of the characteristic lather. In 
 these cases it is better to dilute 25 c.c. of the sample with 25 
 c.c. of distilled water, proceed as explained, when the net amount 
 of soap solution used will indicate the hardness in parts per 
 100,000. 
 
 To determine the Permanent Hardness, place 100 c.c. of 
 the sample in a flask and boil for fifteen minutes. On allowing 
 
WATER ANALYSIS. 9 1 
 
 to cool, all the calcium and magnesium carbonate, with most of 
 the iron, if any be present, will form a precipitate at the bottom 
 of the flask, but some of the magnesium carbonate will have 
 become redissolved. This precipitate will represent the temporary 
 hardness for the most part, while the permanent hardness will 
 still exist in the supernatant liquid. Carefully decant this clear 
 liquid into a measuring-glass, taking care not to shake up the 
 precipitate. Measure it, and make up to the original bulk of 
 ioo c.c. with distilled water. Estimate the hardness, as explained 
 above, in 50 c.c. of it. The result will be the permanent hard- 
 ness, and the difference between that and the total hardness will 
 represent the temporary hardness. 
 
 Say, 50 c.c. of the water thus treated required i*6 c.c. of 
 soap solution. Deducting o'2 c.c. for lather, we get 1*4 c.c. 
 and 1 "4X2 "5x2 = 7 mgms. of calcium carbonate present in 
 100 c.c. of the water, and these 7 mgms. CaC0 3 represent the 
 permanent hardness of 100 c.c. (100,000 mgms.) of the water 
 sample, or, in other words, 7 parts per 100,000 of permanent 
 hardness. 
 
 The total hardness was n parts per 100,000, therefore the 
 temporary hardness equals n — 7=4 parts per 1 00,000. 
 
 The total hardness of a water should not exceed 30 parts per 
 100,000, otherwise it is unsuitable for domestic purposes. What 
 are called hard waters vary from 20 to 30 degrees on the metrical 
 scale, a soft water from 8 to 15, while a very soft water may 
 contain up to 6 or 8. 
 
 The permanent hardness should not exceed 6 parts per 
 100,000. Of course the greater the proportion of temporary to 
 permanent hardness, the better, since the former is, to a large 
 extent, remediable, while the latter is not. 
 
 The Estimation of the Ammonia in a Water Sample. 
 
 This and the following analytical procedures aim essentially 
 at obtaining evidence of organic matter in water. The organic 
 matter may be of either animal or vegetable origin, but in every 
 case exhibits a natural tendency to resolve itself into simple parts, 
 more particularly into ammonia and oxidized salts of nitrogen, 
 such as nitrites and nitrates. The process known as that of 
 Wanklyn, Chapman, and Smith, recognizes two kinds of ammonia, 
 namely, the free or saline ammonia, and the albuminoid ammonia. 
 
 The free or saline ammonia represents the ammonia combined 
 with carbonic, nitric, and other acids, and also what may be 
 derived from urea or other easily decomposed substances. 
 
92 WATER. 
 
 The albuminoid ammonia is that which can be derived from 
 the breaking up of organic matter by the addition of a solution 
 of strongly alkaline permanganate of potassium, and then 
 boiling. 
 
 To estimate the ammonia in a water sample it is necessary to 
 have the following solutions : — 
 
 (i) Nessler's Reagent. — This is a saturated solution of mercuric 
 iodide in potassium iodide. It gives a yellowish tinge, with the 
 faintest trace of ammonia, passing, if much ammonia is present, 
 to the formation of a yellow-brown precipitate of the di-mer- 
 curammonium iodide. Nessler's solution is prepared by dissolving 
 35 grms. of potassium iodide in ioo c.c. of distilled water. Also 
 dissolve 13 grms. of mercuric chloride in 700 c.c. of distilled water, 
 and mix the two solutions. Add cold saturated solution of mer- 
 curic chloride until a precipitate of the red periodide of mercury 
 just begins to be permanent. The liquid must then be left to 
 cool, and may with advantage stand for a few hours before being 
 rendered alkaline. This is done by adding 160 grms. of solid 
 caustic potash or 120 grms. of solid caustic soda to the liquid, 
 which is afterwards to be diluted with distilled water, so that the 
 whole volume of the solution may equal 1 litre. In order to 
 render the Nessler reagent sensitive, it is mixed finally with a little 
 more cold saturated solution of corrosive sublimate, and allowed 
 to settle. 
 
 (2) A standard solution of Ammonium Chloride. — Ammonium 
 chloride, represented by the formula NH 4 C1, bears a ratio to 
 ammonia, as represented by NH 3 , of as 53*5 is to 17. Therefore 
 if 0*03147 grm. of ammonium chloride be dissolved in 1 litre of 
 distilled water, that solution will be equivalent to o'oi grm. of 
 ammonia, and 1 c.c. of this solution will equal o'oi mgm. of 
 ammonia. 
 
 (3) An alkaline permanganate of potash solution made by 
 dissolving 200 grms. of caustic potash and 8 grms. of potassium 
 permanganate in 1100 c.c. of distilled water, and then rapidly 
 boiling the solution down to 1 litre or 1000 c.c. 
 
 To determine the Free Ammonia, place 250 c.c. of the water 
 sample in a retort and connect with a condenser. Apply heat to 
 the retort and rapidly distil over the retort contents, catching the 
 distillate in a series of Nessler glasses. When three Nessler 
 glasses are thus filled up to their 50 c.c. marks, a fourth is placed 
 to catch the distillate while 1 c.c. of Nessler's reagent is added 
 to each of the first three glasses. If these glasses be placed from 
 left to right in the order in which they received the distillate, the 
 yellow tint created in each of them by the reagent will show a 
 decrease from left to right, because the first 50 c.c. collected will 
 
WATER ANALYSIS. 93 
 
 contain the most free or saline ammonia, and the third the least. 
 If there is no colour in the third or last glass, then all the 
 ammonia will have come over. If, however, the colour is at all 
 distinct in the third glass, a fourth must be collected and tested 
 in the same way. As a rule, all the free ammonia comes over in 
 the first 150 c.c. of the distillate. 
 
 The colour in the glasses is caused by the presence of 
 ammonia, the precise amount of which we proceed to estimate 
 in the following manner. To other Nessler glasses are added 
 varying quantities of the standard ammonium chloride solution, 
 each made up to 50 c.c. with distilled water and 1 c.c. of Nessler's 
 reagent added. When a tint exactly corresponding with that given 
 by the respective 50 c.c. of the water distillate in the presence 
 of 1 c.c. of Nessler's solution has been obtained, the quantity of 
 standard ammonium chloride solution added is read off. This pro- 
 cedure of noting and comparing tints as given by different amounts 
 of ammonia with Nessler's reagent is called " Nesslerizing." 
 
 The presence and degree of colour must be judged always by 
 looking down through the depth of the water in a glass placed 
 upon a white surface. If the tint given by the first 50 c.c. of 
 distillate be very deep or exceed the value of 3 c.c. of the 
 standard ammonium chloride solution, it is often difficult to judge 
 accurately its comparative value, unless it be diluted either with 
 ammonia free distilled water or by adding it to the less deeply 
 tinted distillates in the other glasses, note being taken of the 
 degree of dilution made. 
 
 Suppose, for example, that from 250 c.c. of water placed in the 
 retort, 150 c.c. of distillate were collected in three glasses, the 
 Nessler reagent added, and the last 50 c.c. or contents of third 
 glass are found to contain no trace of ammonia. The whole of the 
 free ammonia in the 250 c.c. of water has therefore been collected 
 in two Nessler glasses. Assume that it was necessary to add 
 
 2 c.c. of the standard solution of ammonium chloride to the com- 
 parison test-glass, in order to match the colour in the glass 
 containing the first 50 c.c. of distillate, and 1 c.c. of the standard 
 solution was needed to match the tint in the second 50 c.c. of 
 distillate. The total amount, then, of free ammonia yielded by 
 the 250 c.c. of water corresponds to the ammonia present in 3 c.c. 
 of the standard solution. But, as each cubic centimetre of the 
 standard solution contains o*oi mgm. of ammonia, therefore 
 
 3 c.c. contain 0*03 mgm. of ammonia : this, multiplied by 0*4 or 
 divided by 2*5, gives 0*012 mgm. of free ammonia in 100 c.c. 
 of the sample or parts per 100,000. 
 
 To determine the Albuminoid Ammonia. — To the residue 
 left in the retort, employed in the last process, add 25 c.c. of the 
 
94 WATER. 
 
 alkaline permanganate solution and 125 c.c. of ammonia free 
 distilled water. Proceed to distill over as before, and continue 
 to do so until no more ammonia comes over. This ammonia is 
 the so-called albuminoid, due to the breaking up of any organic 
 matter present in the water under the influence of an oxidizing 
 agent in the presence of a caustic alkali. The determination of 
 the ammonia in this case is conducted in precisely similar fashion 
 as for the free ammonia. 
 
 Say, in this case, it is found necessary to distil over 200 c.c. 
 in four Nessler glasses before all the ammonia had come over. 
 Assume that the fourth glass of distillate had a colour equal to 
 o*5 c.c. of the standard solution, the third to 1 c.c, the second to 
 2 c.c, and the first to 2*5 c.c. The sum of these amounts represents 
 that 6 c.c of the standard solution were required to match the 
 colour furnished by the albuminoid ammonia in 250 c.c. of water. 
 But as each cubic centimetre of the standard solution equals 
 o'oi mgm. of ammonia, therefore 6 c.c equal o"o6 ragm. • 
 in other words, there are 0*06 mgm. of albuminoid ammonia in 
 250 c.c. of water, or 0*024 mgm. in 100 c.c. or parts per 100,000. 
 
 In this process, before adding the alkaline permanganate 
 solution to the residue in the retort, it is as well to boil it (the 
 permanganate) for five minutes in order to get rid of any traces 
 of ammonia which may be in it. 
 
 In drinking water, the tree ammonia should not exceed 
 0*005 P er 100,000, and the albuminoid ammonia not exceed o'oi 
 per 100,000. The presence of much free ammonia with excess 
 of chlorine, nitrites and nitrates, usually denotes animal pollution. 
 Much albuminoid, with a small amount of free ammonia, indicates 
 vegetable contamination, particularly so if the chlorides, nitrites, 
 and nitrates are low. Rain water often contains a large amount 
 of free ammonia, probably derived from soot, and appears to be 
 harmless. Deep wells often show much free ammonia and 
 chlorides without necessarily indicating pollution • but the same 
 amounts in a shallow well would be very suggestive of sewage 
 or at least urine. 
 
 Estimation of Nitrites in a Water Sample. 
 
 When organic matter putrefies or decomposes, it becomes 
 reduced to its absolute elements. Of these nitrogen is the chief, 
 and this combining with hydrogen forms first ammonia ; hence 
 the presence, more or less, of free or saline ammonia in a water 
 when at all polluted with organic matter, such as raw sewage. In 
 the course of time, or as it percolates through the soil, the 
 
WATER ANALYSIS. 95 
 
 ammonia in the water acquires oxygen, and gradually becomes 
 partially oxidized to nitrous acid, HN0 2 , or to nitric acid, HN0 3 , 
 which acids, by combining with bases like calcium, sodium, or 
 potassium, form nitrites and nitrates. The oxidation of organic 
 matter cannot go beyond the formation of nitric acid and nitrates, 
 while the nitrous acid and nitrites mark an intermediate stage of 
 imperfect oxidation. 
 
 The determination of nitrites and nitrates in a water is 
 important as indicating either a pollution at some remote period 
 with possibly dangerous matter, or more recently with a partially 
 or completely oxidized sewage. Waters fouled by vegetable 
 matter yield, as a rule, little nitrite or nitrate, chiefly because not 
 only does vegetable decomposition yield relatively little nitrogen, 
 but also because the natural tendency of all plant life is to remove 
 both nitrites and nitrates from a water. 
 
 To determine the Nitrites, we require the following three 
 solutions : — 
 
 (1) Dihite sulphuric acid, consisting of one volume of strong 
 acid to two of distilled water. 
 
 (2) A solution of meta-phenylenedia??iine, made by dissolving 
 5 grms. of meta-phenylenediamine in a litre of distilled water, 
 rendered acid with sulphuric acid. This should be decolourized, 
 if necessary, by filtering through animal charcoal. 
 
 (3) A milli-normal standard solution of potassium nitrite. — 
 Owing to the unstable nature of this salt, it is necessary to prepare 
 it specially for making up this solution. By the following chemi- 
 
 cal equation, A § NC * + KC1 = A ^ C1 + K , N0 >, it is seen that 
 
 4 154 74*5 ,i43'5 8 5 
 
 154 parts of pure silver nitrite in the presence of 74*5 parts of 
 
 potassium chloride are decomposed with the formation of 143*5 
 
 parts of silver chloride, and 85 parts of potassium nitrite or 46 of 
 
 nitrous acid as represented by N0 2 . Hence, if 1*54 grms. of 
 
 pure silver nitrite be dissolved in hot water, decomposed with a 
 
 slight excess of potassium chloride, allowed to cool, made up to 
 
 N 
 a litre, we obtain a solution of potassium nitrite, equalling 0*46 
 
 grm. of nitrous acid as N0 2 . If each 100 c.c. of this solution 
 
 after standing, and subsidence of the silver chloride, be again 
 
 N 
 diluted up to a litre with distilled water, we get a solution of 
 
 1000 
 KN0 2 , equalling 0*046 grm. of N0 2 , and each cubic centimetre of 
 which equals 0*046 of a milligramme of N0 2 . 
 
 The Process consists in placing 50 c.c. of the water sample 
 in a Nessler glass and adding thereto 1 c.c. of both the dilute 
 sulphuric acid and meta-phenylenediamine solutions : if an 
 
g6 WATER 
 
 orange colour is produced immediately, the tint will prove too 
 
 deep for comparison, and another trial must be made with 25 c.c. 
 
 of the water diluted up to 50 c.c. with distilled water, when probably 
 
 only a faint colour will be perceived. The object of this preliminary 
 
 trial is to find out the amount of water which can be used in the 
 
 experiment ; the proper amount is that which gives only a faint 
 
 trace of colour on the addition of the reagents. Having decided 
 
 the amount which can be used, it must, if less than 50 c.c, be 
 
 diluted up to this amount with distilled water, and then placed in 
 
 a Nessler glass. Trial glasses containing different amounts of the 
 
 standard nitrite solution diluted up to 50 c.c. with distilled water 
 
 are then made. One c.c. of the dilute sulphuric acid and ice. 
 
 of the meta-phenylenediamine are next added to the Nessler glass 
 
 containing the water to be examined and to each of the trial glasses 
 
 as quickly as possible, so that the colours in them may develop 
 
 from exactly the same time. The glasses are compared at the end 
 
 of ten to fifteen minutes, and the amount ot standard solution 
 
 determined, which gives the same colour as the nitrite in the water 
 
 under examination. If the tints are not matched exactly at the 
 
 first time, a second attempt must be made, all the glasses being 
 
 filled again at exactly the same time. The standard potassium 
 
 nitrite, being of the strength of 1 c.c. = 0*046 mgm. of NO 
 
 or nitrogen tetroxide, the number of cubic centimetres used gives 
 
 the milligrammes of N0 2 present in the sample of water. Assuming 
 
 that 2 c.c. of the standard potassium nitrite are placed in a Nessler 
 
 glass, made up to 50 c.c. with distilled water, receive 1 c.c. each of 
 
 dilute acid and meta-phenylenediamine, and the same shade of 
 
 tint obtained as that yielded by 25 c.c. of water sample after 
 
 dilution to 50 c.c. and the addition of 1 c.c. each of dilute acid 
 
 and meta-phenylenediamine; then 2 X 4 X 0*046 = 0*368 mgm. 
 
 N0 2 in 100 c.c. of water or parts per 100,000: multiplying this 
 
 N 
 ky xfrT or 4?> we & et *^ e e( l u i va l ent m terms of nitrogen. 
 
 It may be accepted as a good rule that no water which shows 
 the presence of nitrites is fitted for domestic use. 
 
 Estimation of Nitrates in Water Sample. 
 
 A process which is both simple and satisfactory is that known 
 as the phenol-sulphuric acid method : for it the following solutions 
 are required : — 
 
 (1) Phenol-sulphuric acid^ made by adding 6 grms. of pure 
 phenol and 3 c.c. of distilled water to 37 c.c. of strong sulphuric 
 acid free from nitrates. 
 
 (2) Standard solution of potassium nitrate, made by dissolving 
 
 2 
 
WATER ANALYSIS. 97 
 
 0*0722 grm. of recently fused potassium nitrate in water, and 
 the solution subsequently made up to a litre. One c.c. of this 
 solution will contain o*oi mgm. of nitrogen. 
 
 The process is thus performed: 10 c.c. or the water under 
 examination and 10 c.c. of the standard potassium nitrate solu- 
 tion are evaporated separately just to dryness in two porcelain or 
 platinum dishes. To each of the residues, 1 c.c. of the phenol- 
 sulphuric acid is added and thoroughly mixed by means of a 
 glass rod. If the water under examination contains a large 
 amount of nitrates, the liquid will quickly turn red ; if it contains 
 but a small quantity, this colour will not appear for about ten 
 minutes. After the dishes have stood from ten to fifteen minutes, 
 their contents are washed out successively with 25 c.c. of distilled 
 water into two clean Nessler glasses, about 20 c.c. of liquor 
 ammonias (sp. gr. 0*96) added, and both made up to 100 c.c. with 
 more distilled water. 
 
 Any nitrate present in the solutions converts the phenol- 
 sulphuric acid into picric acid, which, by the action of the 
 ammonium, forms ammonium picrate : this gives a yellow colour 
 to the solution, the intensity being proportional to the amount 
 present. 
 
 The colours of the two solutions are now compared, and the 
 darker one diluted until the tints are adjusted, the calculation 
 being made as explained in the preceding tests for nitrites. 
 
 Suppose 10 c.c. of the sample and 10 c.c. of the standard 
 nitrate solution have, after treatment and dilution each to 100 c.c, 
 given two shades of yellow, that from the standard solution being 
 the darker. This, on dilution to 200 c.c, is still found to be 
 too dark, but this, again on further dilution to 900 c.c, gives 
 the desired match in colour. As the 10 c.c of standard 
 solution originally treated equal o'i mgm. of nitrogen, then 
 900 : 100 : : 01 : x = o'oir mgm. of nitrogen in 10 c.c. of the 
 water sample, or on part of nitrogen from nitrates per 100,000. 
 If expressed as N0 8 , this equals 0*43 per 100,000. 
 
 In the case of very pure waters, it is better to evaporate down 
 20, 50, or more c.c. of the sample, and only 5 c.c of the standard 
 nitrate solution. Conversely, if the sample be rich in nitrates, it 
 must be diluted down with distilled water. 
 
 No water used for drinking purposes should contain more than 
 0*35 part per 100,000 of nitrogen in the form of nitrates, unless, 
 of course, the geological strata are such as can be legitimately 
 regarded as the source from which the water derives these salts. 
 
 E 
 
98 WATER. 
 
 Estimation of the Oxygen Consuming Power of a 
 
 Water Sample. 
 
 Although by itself of little value as a measure of the organic 
 impurity, still the power of consuming or affinity for oxygen which 
 a water sample has, when taken in conjunction with other 
 analytical facts, is often a material aid in forming an opinion as 
 to the quality of any particular water. Much of the organic 
 matter present in water is capable of oxidation, but since the 
 ease of oxidation bears no constant ratio to the nature of the 
 organic matter, its estimation affords no very reliable index to 
 the real pollution present. In all the efforts to judge the 
 oxidizable organic matter, advantage is taken of the fact that, in 
 the presence of organic substances, permanganate of potassium, 
 KMn0 4 , freely parts with its oxygen until all the permanganate 
 has been reduced to hydrated manganese dioxide : thus, 
 2KM11O4 = K 2 Mn0 4 + Mn0 2 + 2 : in everyday life, this change 
 is marked by the pink colour which this salt originally gives 
 to water being replaced by a brown. Unfortunately, different 
 substances reduce different proportions of permanganate, and 
 slight variations in temperature and acidity or alkalinity mate- 
 rially influence the readiness with which the permanganate parts 
 with its oxygen. 
 
 To determine the Oxidizable Organic Matter, use is best 
 made of what is known as Tidy's process. This process is based 
 upon the chemical fact that in the presence of an acid and heat, 
 the following decomposition of permanganate takes place : — 
 4KMn0 4 + 6H 2 S0 4 = 2K 2 S0 4 + 4MnS0 4 + 6H 2 + 50 2 , or, in 
 other words, 632 parts of potassium permanganate yield in the 
 presence of sulphuric acid 160 parts of oxygen. 
 
 For Tidy's process, the following solutions are necessary : — 
 
 (1) Staiidard potassium perma?iganate solution. — Since 632 
 parts of the salt with an acid yield 160 parts of oxygen, then 
 °'395 g rm - °f potassium permanganate, if dissolved in a litre 
 of water, will be equivalent to o # i grm. of oxygen. This con- 
 stitutes the standard solution, and 1 c.c. of it used with acid 
 yields o*i mgm. of oxygen. 
 
 (2) Potassium iodide solution. — A 10 per cent, solution in 
 distilled water. 
 
 (3) Sodium thiosulphate solution. — One grm. dissolved in a 
 litre of distilled water. 
 
 (4) Starch solution. — One grm. of starch, mixed with \ litre 
 of distilled water, boiled for five minutes and filtered. 
 
 (5) Dilute sulphuric acid, consisting of one volume of strong 
 acid to three of distilled water. 
 
WATER ANALYSIS. 99 
 
 In performing this process, Tidy recommended two determi- 
 nations to be made, namely, one of the oxygen absorbed after 
 fifteen minutes' exposure at a temperature of 8o° F., and one after 
 four hours' exposure at the same temperature. He considered 
 that during the first quarter of an hour, the more or less putrescent 
 easily oxidized animal organic matters were oxidized, while the 
 oxidation of the vegetable organic material did not take place 
 till after four hours or so. Practically, as much information as can 
 be gained is obtained at the end of fifteen minutes ; therefore, 
 except in special cases, the second observation after four hours 
 is hardly necessary. If required, it is performed exactly in the 
 same manner as the shorter exposure. 
 
 Into a stoppered bottle, capable of holding from 300 to 
 400 c.c, place 250 c.c. of the water sample, and heat in a 
 water-bath to 8o° F. (26°7 C.) ; when the required temperature 
 is reached, run in 10 c.c. of the dilute sulphuric acid and 10 c.c. 
 of the permanganate solution. A pink colour will result. Main- 
 tain the bottle contents at 8o° F., carefully noting whether the 
 pink tint is discharged ; if the tint disappear, add more perman- 
 ganate. At the end of fifteen minutes, add to the water three 
 drops of the iodide of potassium solution. Owing to there being 
 a certain amount of oxygen available from the permanganate, as 
 previously explained, this will liberate iodine from the iodide, with 
 the result that the pink-coloured bottle contents will now become 
 yellow: thus, 50 2 -f- 20KI + ioH 2 = 20KHO + ioI 5 . The 
 quantity of iodine set free will, of course, be dependent on the 
 amount of potassium permanganate remaining unreduced in the 
 water. If the iodine set free is absolutely dependent upon 
 the amount of permanganate left unreduced by the organic matter 
 in the water, it is obvious that any estimation of the iodine libe- 
 rated will be a measure of the unused oxygen, and this deducted 
 from what was rendered available by the original quantity of 
 permanganate added, will give a measure of the oxidizable organic 
 matter in the 250 c.c. of water. 
 
 We proceed to make these estimations in the following manner : 
 To the iodine-tinted water, the thiosulphate solution is gradually 
 added with the object of reducing it : thus, I a + 2Na 2 S 2 3 = 2NaI 
 + Na 2 S 4 6 . In order to know exactly when all the free iodine has 
 been removed from the water, an indicator in the form of 1 c.c. of 
 the starch solution is added ; this, so long as any free iodine is 
 present, will give a blue tint. Therefore, continuing the addition 
 of the thiosulphate, we stop the moment all the blue colour has 
 gone, and read off the actual amount of thiosulphate used. 
 
 Unfortunately, thiosulphate of soda is a very unstable salt, 
 and its particular value as a reducing agent needs to be judged, 
 
100 WATER. 
 
 at the time of each experiment, by means of a control observation 
 of its power upon an identical quantity of permanganate in 
 distilled water, as was used for the unknown sample. Accord- 
 ingly, into a similar bottle, 250 c.c. of distilled water are placed, 
 heated to 8o° F., 10 c.c. of the dilute sulphuric acid, and exactly 
 the same amount of permanganate as was used for the water 
 sample added, and the whole kept at 8o° F. for fifteen minutes. 
 In this bottle, owing to there being no organic matter, practically 
 the whole of the oxygen liberated from the permanganate under 
 the circumstances will be unconsumed, and consequently, on the 
 addition of three drops of potassium iodide, more iodine will be 
 liberated, and more of the thiosulphate will be required to reduce 
 it. The iodide, the starch, and the thiosulphate are added pre- 
 cisely as in the other experiment. 
 
 So soon as all the iodine has been removed, as shown by the 
 disappearance of the blue colour, the amount of thiosulphate 
 used is read off; its volume will represent, for the time being, 
 the actual reducing value of the thiosulphate for the precise 
 amount of permanganate used or added in the experiment. And 
 the difference between the amount of thiosulphate solution needed 
 to reduce the x amount of potassium permanganate in this pure 
 distilled water, and that required for the same amount which has 
 been more or less decomposed or reduced by oxidizable organic 
 matter in the water sample, will represent the quantity of oxygen 
 consumed by such oxidizable matter. 
 
 Example. — Say 10 c.c. of KMn0 4 in the distilled water has 
 used up 40 c.c. of the thiosulphate solution; therefore 40 c.c. 
 of the thiosulphate may be considered as equivalent to 10 c.c. 
 of permanganate, or 1 mgm. of oxygen, because each cubic 
 centimetre of KMn0 4 equals o*i mgm. of oxygen. 
 
 Another 10 c.c. of KMn0 4 , in the unknown water sample, 
 used up, say, 32 c.c. of the thiosulphate solution ; therefore an 
 amount of oxygen equivalent to the difference between 40 and 
 32 or 8 c.c. of the thiosulphate solution has been taken up by 
 the organic matter. But if 40 c.c. of thiosulphate equal 1 mgm. 
 of oxygen, then 8 c.c. equal 0*2 mgm. of oxygen. This means 
 that 0*2 mgm. of oxygen is taken up by 250 c.c. of the water 
 sample, or parts per 250,000; this multiplied by 0*4 equals 
 o*o8 parts of oxygen consumed by the organic matter per 
 100,000. 
 
 In performing this process, the permanganate added must be 
 sufficient to create a pink colour, which remains distinctly per- 
 manent at the end of the heating. If the four-hour test be 
 applied, it may be necessary to make repeated additions of the 
 permanganate solution. The total quantity actually used must be 
 
WATER ANALYSIS. 1 01 
 
 carefully noted, and the same amount of course employed in the 
 distilled water experiment. 
 
 In endeavouring to interpret the results of the oxygen process, 
 it must be borne in mind that besides organic matter, iron salts, 
 nitrites, and sulphuretted hydrogen will reduce permanganate of 
 potassium, and these latter, if present, must be duly allowed for. 
 It is difficult to distinguish between the oxygen consumed by the 
 nitrogenous and the non-nitrogenous organic matter. Roughly 
 speaking, the four-hour experiment gives information as to the total 
 amount of oxidizable organic matter, while the fifteen-minutes' 
 reaction is valuable as indicating the proportion of putrescent or 
 readily oxidizable and presumably dangerous material. Peaty 
 waters consume large quantities of oxygen ; hence, as in all other 
 attempts to measure the organic matter in a water sample, the 
 results of the oxygen process must be considered in conjunction 
 with the other analytical data and the source of the water. 
 
 In a general way, it may be said that waters of great organic 
 purity will not consume more than 0*05 of oxygen per 100,000 in 
 fifteen minutes at 8o° F., and that when the oxygen consumed 
 exceeds o*i per 100,000, the sample may be considered of doubt- 
 ful purity. 
 
 Determination of Dissolved Oxygen. 
 
 This estimation in connection with the examination of waters 
 and sewage effluents is occasionally needed, but for practical 
 purposes the method must be simple, speedy, accurate, and not 
 require large quantities of the sample. A further condition is 
 that the waters must not be subjected to a diminished oxygen 
 pressure, i.e. must not be operated upon in an atmosphere of 
 inert gas, otherwise there might be a rapid loss by diffusion. 
 Several methods for determining the dissolved oxygen in water 
 have been proposed : the chief objection to them has been the 
 necessity of special apparatus. As being, perhaps, the most 
 simple and readily applied we here describe a method suggested 
 by Winkler. 
 
 The following solutions are required for the process : — 
 
 (1) Manga?ious chloride solution, made by dissolving 80 grms. of 
 MnCl 2 .4H 2 in 100 c.c. of distilled water. The solution must be 
 free from iron. 
 
 (2) Potassium iodide and caustic soda solution. — Dissolve 10 
 grms. of iodide of potassium in 100 c.c. of a 33 per cent, 
 solution of pure caustic soda. This solution when diluted with 
 water and acidified with sulphuric acid ought not to give any 
 colour with a solution of starch. 
 
102 WATER 
 
 (3) Centi-normal solution of iodine, made by dissolving 1*27 
 grms. of pure dry iodine and 2 grms. of iodide of potassium 
 in 20 c.c. of distilled water, and then making up to 1 litre with 
 distilled water. 
 
 (4) Centi-normal solution of thio sulphate of sodium, made by 
 dissolving 2*48 grms. of pure dried Na2S3O3.5H.jO in a litre of 
 distilled water. This solution must be kept in the dark and in a 
 cool place : as its value tends to alter, it should be titrated before 
 use with the above iodine solution, diluted with water and in the 
 presence of some starch solution ; ten c.c. of the iodine solution 
 should require 10 c.c. of the thiosulphate solution for de- 
 colourization. 
 
 (5) Starch solution as prepared for the estimation of oxygen 
 consuming power of a water. 
 
 The Process is as follows : Take a glass bottle provided with 
 a well-fitting glass stopper, and having approximately a capacity 
 of 300 c.c. Determine accurately the capacity of the bottle. 
 Wash out the bottle thoroughly with some of the water to be 
 examined, and then fill it to overflowing. Introduce, by means of 
 a graduated pipette, having a long narrow point, 1 c.c. of the iodide 
 and sodium solution, and also 1 c.c. of the manganous chloride 
 solution. Do this carefully and gradually, so that the point is 
 close to the bottom of the bottle. Put in the stopper tightly, and 
 see that no air-bubbles remain. Mix the contents by swinging the 
 bottle lightly round ; allow the precipitate which forms to settle 
 down ; if it does not readily settle, the bottle should be allowed 
 to stand for an hour or so, but taking care that no air gains access 
 to the bottle contents. When the precipitate has settled down 
 and the fluid in the upper part of the bottle is clear, introduce 
 carefully down the side, by means of a pipette, from 3 to 5 c.c. of 
 fuming hydrochloric acid (sp. gr. 1*16 to 1*18), so as to let it fall 
 on to the precipitate ; replace stopper, and swing the bottle gently 
 round until the precipitate dissolves. The iodine-tinted fluid in 
 the bottle is now washed out into a clean beaker with distilled 
 water, and then titrated in the presence of starch with the thio- 
 sulphate solution, 1 c.c. of which equals 0*0000798 grm., or 
 0*055825 c.c. of oxygen. The iodine liberated corresponds to the 
 oxygen present in the water, therefore the cubic centimetres of 
 thiosulphate used multiplied by 0*055825 give the cubic centi- 
 metres of oxygen present in the original volum e of water placed in 
 the bottle, less two or whatever volumes of the iodide and man- 
 ganous solutions have been added. The various chemical reactions 
 which take place in the process may be expressed by the following 
 equations : — 
 
WATER ANALYSIS. 103 
 
 2MnCL, + 4NaOH = 4NaCl 4- 2Mn(0H), 
 2Mn(0H) a + O + H 2 = 2 Mn(OH) 3 
 
 2 Mn(OH) 3 + 6HC1 = 2MnCl 3 + 6H,0 
 
 2M11CI3 + 2KI = 2MnCl 2 + 2KCI + I a 
 
 Example. — Say the capacity of the bottle was 280 c.c. After 
 the necessary manipulations had been made, assume that 32*9 c.c 
 of the thiosulphate solution were used to decolourize the iodized 
 water. This will represent 1*8366 c.c. of oxygen in 278 c.c. of 
 water, or 6'6o66 c.c. in 1 litre. A correction for temperature 
 and pressure is not necessary. 
 
 It must be borne in mind that this process needs to be done 
 rapidly and at once ; it is also interfered with by the presence of 
 much organic matter which absorbs the liberated iodine, and by 
 the presence of nitrites which when acidified set free iodine. Such 
 interference can be prevented to a great extent by working very 
 rapidly and using as little starch as possible. The amount of 
 dissolved oxygen in a water is influenced largely by temperature, 
 being less in summer and greater in winter. Roscoe and Lunt 
 give the following figures as representing the cubic centimetres 
 of oxygen in a saturated water at different temperatures ; namely, 
 at 5 C. 8-68, at io° C. 777, at 15 C. 6-96, and at 20 C. 6*28. 
 Ordinary tap-water in this country contains on an average 7 c.c. 
 of dissolved oxygen per litre ; this is about 1 part by weight per 
 too, 000. 
 
 Estimation of Lead in a Water Sample. 
 
 The only metal that is likely to require quantitative determina- 
 tion is lead. Before making this estimation, it must be first 
 ascertained that the darkening produced by ammonium sulphide 
 is really due to lead, not to iron or copper. 
 
 The reagents required are (1) a saturated solution of am- 
 monium sulphide, and (2) a standard solution of lead acetate, 
 made by dissolving 0*1831 grm. of crystallized acetate of lead, 
 Pb(C 2 H 3 2 ) 2 -3H 2 0, in 1 litre of distilled water. Each cubic 
 centimetre of this solution contains o*i mgm. of metallic lead. 
 
 The Process consists in first evaporating 200 c.c. of the water 
 sample down to 100 c.c, and placing the same in a colour com- 
 parison or Nessler glass on white paper. Add three drops of the 
 ammonium sulphide solution. Note if any darkening is produced. 
 Into a similar Nessler glass put 1, 2, or more c.c. of the standard 
 lead solution, make up to 100 c.c. with distilled water, add three 
 drops of the ammonium sulphide solution, and match the dark 
 colorations. Calculate the amount found in parts per 100,000, 
 and in grains per gallon. 
 
104 WATER. 
 
 Thus, for example, presume water concentrated from 200 to 
 100 c.c. gave a colour equal to 3 c.c. of standard lead solution, 
 with three drops of ammonium sulphide solution. Then 3 X o*i 
 = 0*3 mgm. of lead in the 100 c.c. of water; but this equals or 
 represents 200 c.c. of the original water, therefore, in each 100 c.c 
 there are 0*15 mgm. of lead, or 0*15 cgm. in a litre (parts per 
 ico,ooo); this multiplied by 07 = 0*105 gr. per gallon, or rather 
 more than ^ gr. of metallic lead per gallon. 
 
 Many waters, especially those that are soft and peaty, and 
 therefore liable to act on lead, often possess sufficient colour to 
 equal 0*5 or even 1 c.c. of the lead solution * if this is the case, 
 compare its colour with that produced by a given quantity of lead 
 solution in the presence of three drops of ammonium sulphide, 
 and make any needful deduction accordingly. Care must be 
 taken not to clear the water by nitration, as ordinary filter-paper 
 removes an appreciable quantity of lead. 
 
 No drinking water should contain lead, but ^ gr. per gallon 
 may be placed as the extreme permissible limit. 
 
 Estimation of Iron in a Water Sample. 
 
 This quantitative determination is occasionally required, and 
 can be conveniently performed by the following process, for which 
 these solutions are needed : — 
 
 (1) A sta?idard solution of ferric sulphate, made by dissolving 
 0*0496 grm. of crystallized ferrous sulphate in a litre of distilled 
 water, acidifying with sulphuric acid, and adding sufficient potas- 
 sium permanganate to make a faint pink colour. One c.c. of 
 this solution contains o*oi mgm. of iron. 
 
 (2) Dilute nitric acid. — Dilute 30 c.c. of pure concentrated 
 nitric acid with distilled water to measure 100 c.c. 
 
 (3) A solution of potassium sulpho-cyanate, made by dissolving 
 15 grms. in 100 c.c. of distilled water. 
 
 The Process is as follows : Acidify 50 c.c. of the sample with 
 0*5 c.c. of hydrochloric acid, and add just sufficient of dilute 
 potassium permanganate solution to convert any iron which may 
 be present to the ferric state. Next evaporate this pink-tinted 
 water nearly to dryness in order to drive off any excess of acid, 
 and then dilute to its original volume of 50 c.c. with distilled water. 
 Into each of two Nessler glasses place 5 c.c. of the dilute nitric 
 acid and 5 c.c. of the sulpho-cyanate solution. To one of these 
 glasses add a measured quantity of the treated water sample, and 
 then fill both glasses up to 50 c.c. mark with distilled water. If 
 any iron be present in the treated water sample, a blood-red colour 
 will be produced in the glass to which a measured volume was 
 
WATER ANALYSIS. I05 
 
 added. Into the other glass some of the standard iron solution 
 is added until the colours in both agree or coincide in tint. The 
 precise amount of the treated water sample to be added to the 
 first glass will depend upon the quantity of iron present ; but, as 
 a rule, not more should be used than will require 2 c.c. of the 
 standard iron solution to match it in colour, otherwise the tint 
 produced will be too deep for accurate comparison. The subse- 
 quent calculation is obviously simple, as each cubic centimetre of 
 iron solution represents o*oi mgm. of iron. The result can be 
 expressed either as parts per 100,000 or grains per gallon. 
 
 Examination of Suspended Matter and Deposit. 
 
 Where a sediment forms from a sample of water, it is desirable 
 to take advantage of the valuable evidence which a microscopic 
 examination affords. The most simple method by which the 
 deposited matter can be collected and examined is the following : 
 After well shaking, pour from half to one litre of the sample into 
 a large conical glass, cover it over, and set aside for twenty-four 
 hours ; then decant or siphon off as much of the supernatant water 
 as it is safe to do without disturbing the deposited matter at the 
 bottom of the glass. Some of this sediment should then be taken 
 up by means of a small pipette, and transferred to several glass 
 slides, cover glasses applied, and the examination by the microscope 
 proceeded with, any excess of water upon the slide being removed 
 by clean blotting-paper. The various forms of animal and vegetable 
 life, and of inanimate organic and inorganic material, are best 
 sought by commencing with a low-power lens, say 1 inch, and 
 then passing on to the ^-inch power. The steps necessary for 
 examining the bacterial contents of a water sample are dealt with 
 in a subsequent section. 
 
 The nature of the suspended matter varies greatly, embracing 
 such diverse objects as mineral grit, sand, flint, chalk, and mica 
 particles, woody fibre, fragments of leaves, starch cells, macerated 
 paper, amorphous vegetable debris^ hairs, feathers, down, cotton, 
 wool, or silk fibres, and scales or wings from various insects. The 
 foregoing are all inanimate, but in addition there is often much 
 animate vegetable material, such as fungi, either as spores or 
 mycelia, and numerous forms of algae, as well as living animal forms, 
 such as protozoa, rhizopoda, infusoria, Crustacea, insects, worms 
 and their ova or eggs. The presence of the spores and mycelia of 
 the higher fungi indicates impurity probably derived from sewage, 
 since the latter usually contains phosphates, without which these 
 forms cannot live. Algse, diatoms, and desmids are common in 
 open wells, lakes, ponds, and streams ; they are not an infrequent 
 cause of the peculiar odour developed in such waters. The lower 
 
106 WATER. 
 
 forms of animal life are only found in waters containing organic 
 matter in solution. This material may be derived from decaying 
 vegetable matter. The higher forms of life do not necessarily 
 denote impurity, but the presence of worms or of their ova and 
 embryos is particularly objectionable, since they may be forms 
 which can develop in the human body, and give rise to ill effects. 
 The most suspicious elements which may be detected by a 
 microscopical examination of water sediment are those which 
 point directly or indirectly to the waste products of man. Among 
 the latter are cotton, wool, hair, and linen fibres, while the former 
 include substances which leave the body in the faeces owing to 
 their indigestibility. Under this heading may be mentioned fat 
 cells, starch grains, muscle fibres, various connective tissue 
 elements, shreds of membrane, epithelial cells, fragments of food, 
 and the various parasitic worms either as ova or mature forms. 
 
 The Bacteriological Examination of Water. 
 
 No attempt is made in this section to give a complete study of 
 this difficult and complicated question ; but merely the presentation 
 of the more important facts, and the outline of a working scheme 
 for the routine biological examination of waters, upon which the 
 student, by a further study of the special literature of the subject, 
 can build a more elaborate and complete procedure. It is also 
 assumed that no one will attempt the bacteriological examination 
 of a water sample who has not acquired a knowledge of the 
 necessary experience and technique in a suitably equipped 
 laboratory under the guidance of a competent teacher. For these 
 reasons it is deemed unnecessary to either describe the apparatus 
 to be found in every laboratory, or to enter into details of the 
 comparatively simple technique used in the routine methods of 
 bacteriological work. 
 
 We would say, however, that the bacteriological examination 
 of a water sample constitutes an essential complement to its 
 chemical analysis, and that the latter without the former affords 
 at best but an imperfect gauge as to the freedom of a water from 
 organic contamination. Bacteriological examinations of water 
 samples are mainly undertaken either for testing the efficiency of 
 filter-beds or for the direct detection of pollution from manure or 
 sewage. This information upon which such opinions or conclusions 
 can be based is practically of the following three kinds : — 
 
 (i) A quantitative estimation of the number of micro-organisms 
 present in the sample of water under examination. 
 
 (2) The detection of micro-organisms not necessarily hurtful to 
 
WATER ANALYSIS. 107 
 
 man, but whose presence and origin imply that the sample is more 
 or less contaminated with faecal or manurial pollution. 
 
 (3) The isolation and identification of actual disease-producing 
 organisms. The smaller the volume of water in which the 
 micro-organisms under the second and third headings can be 
 detected the greater the pollution, and vice versa. 
 
 Collection and Transmission of Samples. — This constitutes a 
 very important procedure, and any carelessness displayed is liable 
 to seriously vitiate the results. The sample should be collected in 
 glass bottles with glass stoppers, previously sterilized at 150 C. 
 for three hours. If sterilization by heat is not feasible, the bottles 
 may be cleaned sufficiently by washing them out with a little pure 
 sulphuric acid, all traces of acidity being removed by rinsing the 
 bottle thoroughly with some of the water to be examined. In 
 the case of rivers, pondSj or lakes, the bottle should be plunged 
 below the surface before the stopper is removed; in this way a 
 sample of the main body of water will be obtained. In some 
 cases, as when the presence of the cholera organism is suspected, 
 it is desirable to examine the surface water. If the source of 
 water is a piped supply, the tap should be opened and the water 
 allowed to run to waste for a few minutes before the sample is 
 collected. It is always desirable, in the case of piped supplies, to 
 obtain, if possible, a sample direct from the main. In the case of 
 wells, particularly if not in constant use, it is advisable to pump 
 continuously for a few hours before collecting the sample for 
 examination. In all cases, after the specimen has been obtained, 
 the glass stopper should be quickly replaced and carefully tied 
 down with a little oiled silk. The next point is to have the sample- 
 examined as quickly after collection as possible. If the specimen 
 cannot be examined at once, it should be packed in ice, and then 
 transmitted to the laboratory. The importance of keeping the 
 sample in the cold is based upon the fact that when the tempera- 
 ture is kept below 5 C, there is practically no increase in the 
 number of micro-organisms in the water. 
 
 For the transmission of samples intended for bacteriological 
 examination, special boxes or carriers are usually employed; 
 these contain one or more glass-stoppered bottles of about eight- 
 ounce capacity, fitting into a tin-lined receptacle, and into which 
 they are carefully secured by a close-fitting lid. This tin case 
 containing the bottle or bottles is surrounded by a metal receptacle 
 for holding ice, this again being surrounded by a thick layer of 
 asbestos and felt, the whole being contained in a strong wooden 
 box or case having a well-adjusted, felt-lined lid, and capable of 
 being securely fastened and locked. In transmitting these 
 carriers to the laboratory, it is of the first importance to do so 
 
108 WATER. 
 
 by the most expeditious route, so as to avoid all possible delay. 
 Full particulars as to the nature and source of the sample should 
 invariably accompany the carrier, as without such information it 
 is difficult to give a satisfactory opinion regarding its hygienic 
 condition. 
 
 The Quantitative Examination. — The determination of the 
 number of micro-organisms in a known volume of water is effected 
 mainly by cultures on solid media, such as gelatine or agar. The 
 method consists in adding varying quantities of the water to tubes 
 of liquefied gelatine or agar : each of these is then thoroughly 
 mixed and poured with suitable precautions into a sterile Petri 
 dish, and solidified as rapidly as possible. These water-plates are 
 then incubated, the gelatine at 20 C. and the agar at 37 C. 
 Each organism present, capable of development under the existing 
 conditions, develops into a mass or colony of bacteria, visible to 
 the naked eye, and as such readily counted. The total number 
 of colonies found gives the number of organisms capable of 
 development in the medium used, and at the particular temperature 
 of incubation. 
 
 The amount of water to be added to the media tubes varies 
 with the suspected degree of pollution; for ordinary waters o*i to 
 o'5 c.c. are routine quantities to add to gelatine tubes, and from 0*5 
 to 1 c.c. to agar tubes. With dirty waters, these amounts will be too 
 large, and greater dilution must be practised. For inoculating the 
 gelatine or agar tubes before plating, 1 c.c. pipettes graduated in 
 one-hundredths of a cubic centimetre are employed, the pipette, 
 after thorough cleaning and plugging of the upper end with cotton 
 wool, being carefully sterilized before use. For enumeration of 
 the colonies, it is convenient to count with the plate on a dark 
 background, dividing the area by lines marked on the plate itself. 
 When plates are very crowded, it may be possible to count 
 colonies in only a few segments, deducing the total bacterial 
 content from these data. Apart from difficulties due to over- 
 crowding, enumeration of colonies on gelatine plates is often 
 impossible owing to the presence of types which more or less 
 rapidly liquefy this medium. The same difficulty arises if working 
 in a hot climate, or under conditions in which solidification of 
 gelatine is impossible. In these cases the routine employment of 
 agar for making water-plates presents advantages, as liquefaction 
 does not take place. But it must be borne in mind that if these 
 plates are incubated at 37 C, the majority of water organisms are 
 suppressed, and consequently the number of resulting colonies will 
 be much smaller than on the gelatine incubated at from 20 C. 
 to 22° C. 
 
 In regard to the number of micro-organisms present in waters 
 
BACTERIOLOGICAL EXAMINATION OF WATER. IO9 
 
 derived from different sources, no hard-and-fast standards can be 
 enunciated. A dirty water will contain many more organisms 
 than a pure water, but the number in a pure supply may vary from 
 50 to 500 per cubic centimetre. When judging the efficiency of 
 water niters, Koch laid down as a standard that satisfactory filtration 
 could not be accepted if the number of micro-organisms exceeded 
 100 in each cubic centimetre of nitrate. As a working basis this 
 standard is adhered to by many observers. The value and 
 importance attaching to the enumeration of the bacteria present 
 in a given quantity of water has been variously appraised. For 
 our own part, we do not think that it, in itself, furnishes information 
 of any great importance. We are forced to this conclusion from 
 the fact that the nature of the medium, its reaction, the duration 
 and temperature of incubation, are all important factors in the de- 
 velopment of water bacteria. It is well known that the reaction 
 of the media used exercises a marked influence on the number 
 of micro-organisms which develop. Until some authoritative 
 standard is arrived at, and all observers agree to adhere to 
 media of that standard reaction, it is difficult to compare results. 
 The American workers recommend all media used in this class of 
 work to be +1*5, that is, acid to the extent of 1*5 per cent, of 
 normal acid, using phenol-phthalein as the indicator. The tendency 
 in this country is to use a -f- 1 per cent, standard, and is the reaction 
 usually employed by ourselves. Again, there is no uniformity of 
 practice as to duration and temperature of incubation. Some 
 count only the colonies visible on the second day, others those 
 visible on the third, fourth, or even fifth days ; some enumerate 
 only colonies visible to the naked eye, others use a lens or low 
 power of the microscope for counting. It seems desirable to be 
 very careful about stating that a given water contains a certain 
 number of organisms per cubic centimetre, as any accurate 
 determination of the kind is practically impossible. The most 
 that should be said is, to state that 1 c.c. of the sample has 
 yielded so many organisms on such and such medium of such a 
 reaction after so many days' incubation at a given temperature, 
 taking care to add whether the colonies included only those 
 visible to the naked eye, or all visible under a certain degree 
 of magnification. 
 
 Qualitative Examination. — This embraces the isolation ana 
 enumeration of organisms not necessarily hurtful, but which from 
 their origin are especially liable to be associated with contamina- 
 tion, also the isolation and identification of actual disease-pro- 
 ducing organisms. Owing to the inherent difficulties in the way 
 of isolating actually specific disease-producing bacteria from a 
 water sample, it must be admitted that in the greater number of 
 
IIO WATER. 
 
 cases we have to rely mainly upon the detection of organisms 
 associated with fsecal or manurial contamination, and although 
 the various methods which have been suggested for this purpose 
 are by no means perfect or completely satisfactory, still, if properly 
 conducted, they may be relied upon to detect pollution, even to 
 the extent of one part of recent sewage in a million parts of water. 
 When the pollution is less than this or when the contamination is 
 far from recent, the bacteriological results usually suffice to raise 
 grave suspicions of pollution, and, if supplemented by an inspection 
 of the source of the water or a knowledge of its history, are sufficient 
 to justify a definite opinion being formed and given. In the 
 light of our experience, the qualitative bacterial method of exami- 
 nation of a water is about a thousand times more delicate than 
 the chemical method. 
 
 A variety of procedures have been proposed for obtaining an 
 indication of the presence or absence of organisms rarely present in 
 waters of known purity, but which are invariably present in 
 sewage-polluted samples. These procedures are based mainly 
 upon the principle of either placing definite volumes of the 
 water into media or under conditions which retard or inhibit 
 the growth of the ordinary water organisms, and yet allow the 
 sewage forms to develop, or placing the water sample into 
 media which foster the growth of organisms of intestinal origin if 
 present, rather than inhibiting the development of the ordinary 
 water bacteria. The most practical method, in our opinion, is 
 associated with the name of MacConkey or some modification 
 thereof. 
 
 MacConkey's Method. 
 
 This consists in adding to varying quantities of the water 
 sample a special medium, first suggested by MacConkey and Hill, 
 namely, bile-salt glucose peptone litmus solution, and incubating at 
 42 C. for forty-eight hours. For the routine examination of 
 waters, a concentrated stock solution should be prepared, made 
 as follows: sodium taurocholate, 15 grms. ; glucose, 15 grms.; 
 peptone, 60 grms. ; litmus solution, a sufficiency to give a deep 
 purple tint ; distilled water, 1 litre. This is boiled and filtered, and 
 then, subject to certain dilutions as detailed hereafter, run in 
 varying quantities into each of a number of clean test-tubes, in 
 which also is a small inverted glass tube (i|- inch by from i to ■§■ 
 inch). The outer tubes, after addition of the solution and plugging 
 with cotton wool, are sterilized for fifteen minutes at ioo° C. on 
 
BACTERIOLOGICAL EXAMINATION OF WATER. Ill 
 
 three successive days. The degree of dilution of this stock 
 solution required depends absolutely upon the volume of water 
 sample to which it is to be added, as it is desirable that in each 
 case the final dilution may contain approximately the same 
 proportion of the bile-salt and other constituents. For the practical 
 application of this medium in the examination of waters, it is 
 desirable to have the test-tubes of two sizes, namely, large ones 
 measuring 8 inches by i inch, and smaller ones 6 inches long and 
 J inch in diameter. With them the following dilutions have been 
 found to work well : — 
 
 (a) Into the large-sized tubes place 30 c.c. of the concentrated 
 stock solution of bile-salt glucose peptone litmus solution, and 
 sterilize in the usual way. To these 50 c.c. of the water to be 
 examined may be added, and then incubated as explained. 
 
 (b) Dilute one volume of the concentrated stock solution with 
 half its volume of distilled water, place 10 c.c. of this diluted 
 solution into each smaller-sized test-tube, and sterilize. To each 
 of these 10 c.c. of the water sample may be added, and then 
 incubated as above. 
 
 (c) Dilute one volume of the concentrated stock solution with 
 an equal volume of distilled water, place 10 c.c. of this diluted 
 solution into each of the smaller-sized test-tubes, and sterilize. To 
 each of these 5 c.c. of the water sample may be added, and then 
 incubated. 
 
 (d) Dilute one volume of the concentrated stock solution with 
 two volumes of distilled water, place 10 c.c. of this diluted solution 
 into each of the smaller-sized tubes, and sterilize. Each of these 
 may then receive 2 c.c. or less of the water under examination 
 and be incubated. 
 
 By this method we have a series of test-tubes containing 
 varying strengths of the bile-salt solution, and, by the addition of 
 varying volumes of the water to be examined, so diluted that 
 they approximately all contain the same proportions of original 
 constituents. Experience shows that the micro-organisms which 
 can grow in this bile-salt glucose peptone solution after incu- 
 bation are divisible into three main classes, namely, (1) those 
 which ferment the medium to the formation of both acid and 
 gas; (2) those which produce acid, but no gas; and (3) those 
 which produce neither acid nor gas, but merely a turbidity. Of 
 course, if the contents of the tubes remain clear, it is evident 
 that the micro-organisms present in the added water are incapable 
 of growing in this particular solution ; as a matter of fact, this is 
 not infrequently the case with pure waters. 
 
 Now, what is trxe interpretation to be placed upon these 
 various results? We may say, at the outset, that the organisms 
 
112 WATER. 
 
 which merely grow, but fail to produce either acid or gas in this 
 medium, have little significance in the hygienic examination of 
 water, as practically none of them can be said to be of faecal 
 origin. Interest, therefore, centres chiefly in the first two classes, 
 as they are, for the most part, organisms of intestinal type, 
 more especially those of class i — that is, producers of both acid 
 and gas — as these include all the more important organisms found 
 in sewage. Moreover, as those coming under the second class — 
 that is, producers of acid only — are invariably associated with 
 others belonging to class i, it is rare to find the production of 
 acid only in this medium, the practical deduction being that it 
 is unnecessary to examine a water sample further if, after having 
 been manipulated and incubated as explained, it is found not to 
 contain micro-organisms capable of producing both acid and gas 
 in the bile-salt glucose peptone litmus solution. 
 
 The chief micro-organisms likely to be met with in a water 
 sample, and which ferment the bile-salt glucose peptone solution, 
 are given in the following table : — 
 
 Group I. 
 
 Group II. 
 
 Producing acid and gas. 
 
 Producing acid but no gas. 
 
 B. coli communis. 
 
 B. typhosus. 
 
 ,, acidi lactici. 
 
 ., dvsenterise. 
 
 ,, lactis aerogenes. 
 
 ,, para-dysenteriae. 
 
 ,, proteus. 
 
 ,, cholerse. 
 
 ,, paracoli. 
 
 ,, prodigiosus. 
 
 ,, paratyphosus. 
 
 Streptococci. 
 
 ,, enteritidis (Gartner). 
 
 Staphylococci. 
 
 And other members of the 
 
 
 intermediate group. 
 
 
 In addition to the above-named organisms, it must be clearly 
 understood that a certain number of micro-organisms exist in 
 water, often of undoubted purity, which are capable of producing 
 acid in this medium, and occasionally minute quantities of gas. 
 This fact emphasizes the need of recognizing these reactions 
 merely as preliminary steps in the inquiry as to the existence or 
 absence of objectionable or hurtful types of bacteria in any given 
 water sample, and that no hasty conclusions are to be drawn from 
 the production of gas, and still less so from the mere acidification 
 of the medium after inoculation with varying quantities of water. 
 For these reasons it is imperative to continue the investigation 
 before deciding that the water is polluted. This further investi- 
 gation involves the plating out in gelatine, or upon lactose agar or 
 any other medium suitable for the isolation and differentiation of 
 
BACTERIOLOGICAL EXAMINATION OF WATER. 1 1 3 
 
 specific species. We deem it necessary to lay stress upon this 
 warning, as some workers are tempted to regard these preliminary 
 reactions as specific evidence of pollution. They certainly are 
 not that, though in nine cases out of ten the production of acid 
 and gas in any of the tubes is strong presumptive evidence of the 
 presence of organisms, in the water, which have been derived from 
 sewage or manurial matter. 
 
 Assuming, then, that one or more of the bile-salt tubes, after 
 inoculation with the water sample, have shown acid and gas pro- 
 duction, it is then necessary to plate out for the exact differen- 
 tiation of species. This is best done by making a series of 
 gelatine plates from the tube or tubes which have given the reaction 
 after inoculation with the smallest volume of the water sample. 
 The colonies which develop on the plates must then be examined, 
 any suspicious ones fished off on to agar slopes, and from these 
 cultures further subcultures made in the various media, to be 
 mentioned, to establish the identity of the particular micro-organ- 
 isms isolated. The various organisms liable to be found in water, 
 capable of producing gas in glucose bile-salt solution, and con- 
 sequently likely to develop on the various plates set from the 
 original water-seeded biie-salt glucose peptone tubes, may be 
 divided into four great groups. In the first are a number of 
 motile organisms of a somewhat unstable biological equilibrium, 
 which liquefy gelatine, produce gas in glucose and sucrose, but not 
 in lactose, curdle milk very slowly, rendering it acid, and com- 
 monly produce indol in peptone solutions. These organisms 
 represent the great proteus family. In the second group are 
 motile bacteria, producing gas in glucose, lactose, mannite, and 
 occasionally in sucrose. These curdle milk rapidly with no pep- 
 tonization of the clot ; they nearly always produce indol in peptone 
 solution, but do not liquefy gelatine. They grow characteristically 
 in both of Proskauer and Capaldi's media, producing acid in 
 No. i and alkali in No. 2. These organisms are the B. coli com- 
 munis, indifferently derived from the alimentary canal of man and 
 animals. In the third group are non-motile bacteria, not lique- 
 fying gelatine, which not only curdle and render milk acid, but 
 ferment sugars, other than glucose, somewhat variably. The 
 type of this group is the B. lactis cerogenes. In the fourth group 
 we find motile bacteria, fermenting glucose alone of the sugars, 
 not liquefying gelatine and not clotting milk, but rendering it 
 finally alkaline. These organisms are the intermediates of the 
 colon-enteric series, and include such species as the B. enteritidis 
 of Gartner, the various para-colons and the paratyphoids. Indol 
 production is variable with this series, but not infrequent. 
 
 It will be apparent from this summary that the liquefaction or 
 
114 WATER. 
 
 non-liquefaction of the gelatine constitutes a broad line of differ- 
 entiation between the first group and the others ; but it must be 
 borne in mind that all the liquefying colonies on a gelatine plate 
 prepared in this way are not necessarily members of the proteus 
 ^roup. though, as a matter of fact, owing to the bile-salt appa- 
 rently keeping back or inhibiting the growth of the common 
 water organisms, which are also capable of liquefying gelatine, 
 the greater number will be found to belong to the great proteus 
 family. Members of this group are invariably found in sewage 
 and in dirty waters, especially where surface washings from 
 manured land gains access to a water supply, consequently their 
 presence in great numbers constitutes a suspicious piece of 
 evidence. On the other hand, one occasionally meets with 
 members of this group in undoubtedly clean and safe waters, but 
 in these cases there is usually a complete absence of members of 
 the other three groups ; therefore, in attempting to appraise them 
 at their proper hygienic value, one must have regard to all the 
 facts, more particularly taking into consideration their association 
 or non-association with members of the other groups. In the 
 same way, it must not be hastily assumed that all the non-lique- 
 fying colonies are necessarily either B. coli or B. lactis o?rogenes y 
 or one of the various paracolons and paratyphoids : the exact 
 determination of species can be made only by careful subculturing 
 in a variety of media, and a critical noting of their morphology 
 and other features. Precisely the same remarks apply to colonies 
 which may develop on gelatine or other plates inoculated from 
 bile-salt glucose solution, in which acid, but no gas, has formed 
 after the addition of some of the water sample. Some of these 
 may liquefy gelatine (e.g. the cholera vibrio) and some will not. 
 Each one of the resulting colonies on these plates will need to be 
 judged upon its individual features as manifested by subculture in 
 various media. Probably the most reliable information will be 
 obtained by subculture in various sugars and glucosides to observe 
 their fermentative effects. This is particularly true of the various 
 micro-organisms allied to the B. coli communis. The best media 
 to employ for this purpose are sucrose, adonit, dulcit, and inulin. 
 These should be made up with sugar-free peptone, bile-salt, and 
 neutral red in accordance with the following formula : peptone 10 
 grammes, bile-salt 5 grammes, the particular sugar 5 grammes, 
 water 1 litre, with 5 ex. of a 5 per cent, solution of neutral red. 
 Each test tube containing these sugars must contain a small 
 fermentation tube, and the reaction considered to have taken 
 place if acid and gas are developed ; the gas production is often 
 scanty. Each kind of sugar tube must be separately marked, and 
 after inoculation incubated at 42 C. for 48 hours. MacConkey 
 
BACTERIOLOGICAL EXAMINATION OF WATER. 1 1 5 
 
 suggested the division of all lactose fractors in the four following 
 groups : 1, those which do not ferment either saccharose or 
 dulcit ; 2, those which ferment dulcit but not saccharose ; 3, 
 those which ferment both dulcit and saccharose ; and 4, those 
 which ferment saccharose but not dulcit. Of itself, this laboratory 
 classification is of little value, unless we can say that one or other 
 of the groups is characteristic of human or animal excreta, or 
 better still if we can split the groups further into individual 
 species for separate study as to their sanitary significance. 
 MacConkey's work suggests that groups 1 and 2 are more 
 common in human faeces, and groups 1 and 4 in animal 
 excrement ; that is in England. Speaking from personal ex- 
 perience, we are inclined to think that those which ferment dulcit 
 but not saccharose are the more faecal type, but the group is not 
 entirely composed of these objectional varieties. Apart from 
 fermentation tests, importance attaches to the production or non- 
 production of indol and to what is known as the Voges-Proskauer 
 reaction. For the indol test, it will be advisable to employ benzal- 
 dehyd, which is a mixture of the persulphate of potash and para- 
 diethyl amido-benzeldehyd. The reaction by this reagent is far 
 sharper and more exact than that given by the older acid method. 
 The Voges-Proskauer reaction is obtained by growth in a 
 medium consisting of peptone 10 grammes, glucose 5 grammes, 
 water 1 litre. It is carried out in a fermentation tube, as in the 
 case of the other sugars, but without any neutral red. The 
 reaction is the slow production of a rose-red colour in the closed 
 end of the fermentation tube, after incubating for 48 hours, on the 
 addition of a few drops of a concentrated solution of caustic 
 potash. The reaction may not show for quite two hours. This 
 reaction in respect of faecal bacteria would seem to be much 
 neglected by routine workers. 
 
 While no detailed description can be given of all the possible 
 microbial forms which may be met with in the bacteriological 
 examination of w r ater, still the following short statement, regard- 
 ing the chief varieties which have a dominant significance in this 
 branch of hygienic investigation, may be of use. The composition 
 and mode of preparation of the various other media mentioned 
 are detailed in the Appendix. 
 
 B. proteus. — A small bacillus with rounded ends, often in pairs 
 or in chains : it is motile, and not spore-bearing ; grows at 42 C, 
 but better at 20 C. It stains with Gram's method. The colonies 
 on gelatine plates after twenty-four hours are delicate granular films 
 of irregular shape j in forty-eight hours they begin to liquefy, and 
 appear like punched-out circles. The colonies in the early stage 
 are usually circular ; the margin may show a fine bristly forma- 
 
Il6 WATER. 
 
 tion or spindle-shaped processes tending to run out all over the 
 gelatine. When grown as a gelatine stab culture, the medium is 
 rapidly liquefied in a funnel-shaped manner. In broth, the growth 
 is diffuse, without pellicle ; on agar, the growth is not characteristic, 
 being moist and greyish-white ; on potato, it is moist but yellowish. 
 In media containing glucose or sucrose there is production of both 
 acid and gas, but in lactose there is no fermentation. In milk, clot- 
 ting occurs in about two days with formation of acid, and in peptone 
 solution there is usually production of indol after about five days. 
 
 B. lactis serogenes. — A non-motile rod decolourizing with 
 Gram's stain. On gelatine plates the surface colonies are porce- 
 lain white in colour, and more or less circular • the deep colonies 
 are round, granular, and yellowish-brown in tint. On agar, the 
 growth is opaque and porcelain white. In gelatine stab culture, 
 the growth is free along the line of inoculation, with a nail-head 
 expansion on the surface ; the gelatine is not liquefied. In milk, 
 there is coagulation usually within forty-eight hours, with marked 
 production of acid. In broth, there is uniform turbidity, and not 
 infrequently some pellicle. When grown in the various sugars, 
 such as glucose, lactose, sucrose, maltose, and in the alcohol 
 mannite, there is marked fermentation with gas production. In 
 peptone and salt solution, there is usually some indol produced 
 by the fifth day, but some strains fail to make indol. Perhaps the 
 most characteristic cultural reaction of this micro-organism is on 
 potato, where it produces a white creamy growth permeated with 
 gas-bubbles. This organism is common in milk, faeces, and dirty 
 water ; it is closely allied to the B. coli communis, and liable to 
 be mistaken for it unless care be taken. 
 
 B. coli communis. — This important micro-organism appears 
 as a very short bacillus, often resembling a coccus. It is usually 
 motile, but occasionally strains are found to be not so. As a rule, 
 it possesses one to five flagella, but owing to their brittleness 
 these are difficult to stain. There is no spore formation. This 
 micro-organism stains readily with ordinary basic dyes, but is 
 decolourized by Gram's method. On gelatine plates, the deep 
 colonies are not unlike those of B. lactis ozrogenes, being oval or 
 circular in shape and brown in colour. After twenty-four to forty- 
 eight hours, the surface colonies are thin, bluish-grey, transparent 
 expansions with an irregular margin. Those of B. lactis cerogenes 
 never show this expansive growth or the crenated margin. The 
 ridges and surface of the B. coli colonies almost invariably shows 
 tracings of furrows running from the centre to the periphery, while 
 at times fine wavy lines parallel to the margin are to be seen. 
 These features of the surface gelatine colonies are usually sufficient 
 to differentiate it from the B. lactis arogenes, whose surface colonies 
 
BACTERIOLOGICAL EXAMINATION OF WATER. 117 
 
 are coarser, less expanded, and altogether lacking in that delicate 
 mother-of-pearl-like appearance so characteristic of the common 
 colon bacillus. The gelatine is not liquefied. As a gelatine 
 stab, there is a nail-head-like surface expansion and marked 
 growth along the line of inoculation. When grown as a streak on 
 a gelatine slope, the growth is white, broad, and marked by a 
 crenated margin. On agar, the growth is not characteristic. In 
 broth, a general turbidity results, but usually no film or pellicle. 
 On potato, the growth commonly takes the form of a thick brownish- 
 yellow layer. Milk is coagulated usually within forty-eight hours 
 after incubation at 37 C. with formation of acidity. Indol produc- 
 tion is almost invariable in peptone and salt solution, after five days' 
 incubation at 37 C. When grown in media containing glucose, 
 lactose, dulcit, maltose, or mannite, there is free production of 
 acid and gas ; some few strains of this organism ferment sucrose, 
 but in our experience the typical B. coli communis derived from 
 the human intestine does not split cane-sugar, adonite or inulin, 
 neither does it give the Voges-Proskauer reaction. When grown in 
 the two media suggested by Proskauer and Capaldi, there is an acid 
 growth in No. 1 after twenty-four hours' incubation at 37 C, while 
 in No. 2 medium there is a similar growth, but the reaction is either 
 unchanged or rendered faintly alkaline. Some writers have laid 
 stress upon the reaction obtained with B. coli comi?iunis when 
 grown in glucose-agar coloured with neutral red, when the magenta 
 red is changed to a yellowish-green florescence after two days' 
 incubation at 37 C. In the majority of cases this does occur, 
 but we are indisposed to regard it as in any way specific or 
 characteristic of this particular micro-organism. The foregoing 
 description gives the chief characteristics of the typical B. coli as 
 commonly met with in dirty water, in sewage, and from human or 
 animal excrement, but it must be borne in mind that varieties are 
 not uncommon which fail to conform to the type. The chief 
 departures from the type are inability to produce indol and to 
 bring about coagulation of milk within three or four days. We 
 have never come across any of these aberrant forms in dirty 
 water without finding them associated with others which conform 
 strictly to the classic type ; it is the association or not with organisms 
 undoubtedly B. coli communis which must guide the worker in 
 the formation of an opinion as to whether he has isolated a 
 presumably faecal organism or not. 
 
 The Intermediates. — Under this heading are embraced a 
 number of micro-organisms which, from their cultural reactions, 
 occupy an intermediate position between the typical B. coli and the 
 B. typhosus. They are motile rods, staining readily with ordinary 
 dyes, decolourizing by Gram's method, not liquefying gelatine, 
 
Il8 WATER. 
 
 and producing on that medium surface colonies which present 
 many points of resemblance to those of the common colon bacillus. 
 Their characteristic features are an ability to gaseously ferment 
 glucose and maltose, make acid in mannite, failing to clot milk, 
 but rendering it finally more or less alkaline. They invariably 
 fail to ferment, even to the formation of acid, either lactose or 
 sucrose. Typical members of this group are the various paracoli 
 bacteria, the paratyphoids, the B, psittacosis, the B. icteroides, 
 the bacillus alleged to be the cause of epidemic jaundice, and the 
 B. enteritidis of Gartner, an organism which has been associated 
 with certain forms of diarrhoea and acute infection presumably 
 due to contaminated or degraded meats. The occurrence of 
 members of this group in water samples is, in our experience, rare, 
 but an appreciation of their biological position, and as possible 
 fermenters of bile-salt glucose broth, is necessary on the part of all 
 those who employ this medium in the routine examination of waters. 
 B. typhosus. — This, the most important representative of the 
 group which produce acid but no gas in bile-salt glucose broth, is 
 a highly motile bacillus without spores, and decolourizing by Gram's 
 stain. It possesses from eight to twelve long wavy flagella disposed 
 all round the bacillus. It grows at 42 C., but better at 37 C. ; it 
 fails to do so at o° C. It is killed by an exposure to 65° C. for ten 
 minutes, and by an exposure of one minute to 8o° C. On gelatine 
 plates, the deep colonies are granular, and round or oval in shape. 
 The surface colonies grow slowly, requiring seventy-two hours 
 usually before they show their characteristic appearances as thin 
 bluish-grey films with an irregular margin ; under a low power mark- 
 ings are seen which look like ridges and valleys running irregularly 
 from the centre to the periphery — in fact, these colonies resemble 
 closely those of the B. coli and some other members of that group. 
 Occasionally the surface colonies of the B. typhosus are without 
 the " relief-map " appearance, and merely finely granular resembling 
 a thin film of glass. The gelatine is not liquefied. When stabbed 
 into gelatine, the surface growth is like the plate-surface colonies, 
 and along the line of inoculation there is a fine growth of discrete 
 white points or masses. If streaked on a gelatine slope, a white 
 narrow growth develops along the line of inoculation with an 
 irregular margin, but the whole growth is less marked than the 
 corresponding culture of B. coli. The main point of distinction 
 between the respective growths of these two micro-organisms upon 
 gelatine is the relative slowness of development on the part of the 
 enteric organism. On agar, the growth is not characteristic, 
 being moist and grey. On potato, a smooth glistening film forms, 
 which is so devoid of colour and structure as to be very difficult 
 of detection with the naked eye. In broth, there results a diffuse 
 
BACTERIOLOGICAL EXAMINATION OF WATER. 119 
 
 cloudiness, without pellicle. In glucose, maltose, and mannite, 
 the B. typhosus produces acid but no gas, while in lactose, dulcit, 
 and sucrose there is not even acid. After a week or more of 
 incubation at 37 ° C. in peptone and salt solution there is no 
 formation of indol. The Volges-Proskauer reaction is negative. 
 Milk, even after a fortnight's incubation at 37 C, is unchanged 
 to the naked eye, but there is invariably the production of 
 some acidity. In the media suggested by Proskauer and 
 Capaldi (see Appendix) the reaction of the B. typhosus is typical, 
 namely, after twenty-four hours' incubation at 37 C. no growth 
 in the No. 1, but a marked acid growth in the No. 2. In these 
 reactions it will be seen this micro-organism differs markedly from 
 the common colon bacillus. If some enteric serum is available, 
 valuable evidence as to identity is obtainable by noting its 
 agglutinability or not. 
 
 Closely allied to the B. typhosus in many of its cultural 
 reactions is the B. dysenteries and certain associated species. 
 From the examination of a considerable number of B. dysenteries, 
 we are disposed to lay stress, as a means of diagnosis, upon the 
 facts that the B. dysenteries is never so motile as the enteric 
 organism; it further never makes acid in mannite, it does not 
 agglutinate with an enteric serum, and, moreover, tends to pro- 
 duce alkalinity in milk on prolonged incubation. In all its other 
 cultural reactions it practically is identical with those described 
 as typical of B. typhosus. The various para-dysentery bacilli, 
 or, as we prefer to call them, the B. typhosi simulantes, offer 
 many points of resemblance to the enteric organism, and as they 
 are not infrequently isolated from waters, their due discrimination 
 is important. Judging by our own experience, these micro- 
 organisms differ from the true B. typhosus only in that they fail 
 to agglutinate with enteric sera; they are at best but feebly motile, 
 usually produce indol, and render milk faintly alkaline. On the 
 other hand, they stand apart from the B. dysenteries, in that they 
 are non-pathogenic to rabbits and guinea-pigs, are not readily 
 agglutinated with dysenteric sera, produce acid in mannite and 
 indol in peptone and salt solution. 
 
 Apart from these, there are many organisms which present 
 superficial resemblances to the B. coli communis and the B. 
 typhosus, and whose isolation from water samples may give rise 
 to difficulties. The more common are the atypical members of 
 the coli group, reference to which has been made already. The 
 B. acidi lactici produces surface colonies somewhat like those of 
 the enteric and colon bacilli ; but it is a spore-bearing organism, 
 coagulating milk, producing indol, and forming gas in glucose 
 media. Another micro-organism which may give trouble is the 
 
120 
 
 WATER. 
 
 B. urece, and occasionally found in dirty water. Its surface 
 colonies on gelatine are of the colon-enteric type, but it does not 
 react to either typhoid or dysenteric sera, and rapidly converts 
 urea into ammonium carbonate. The B. sulcaius is a common 
 water organism which occasionally is mistaken for both B. coli 
 and B. typhosus on gelatine plates in their early stage. It can 
 usually be recognized by the fact that the colonies acquire a 
 yellow colour. Their subcultures are readily distinguished by the 
 facts of not coagulating milk, producing no indol, and forming 
 no gas in glucose. Similar difficulties may arise with another 
 
 Name or number of 
 Organism. 
 
 o 
 
 + 
 
 > 
 
 .•J 
 
 rt 
 W 
 
 V 
 
 a 
 
 B 
 
 a 
 
 u 
 
 O 
 + 
 
 I Liquefies gelatine. 
 
 S 2 
 i. « 
 
 + 
 
 *-• 4) 
 
 v o 
 
 E 3 
 
 S3 a 
 
 fa 
 
 + 
 
 en 
 
 +-> . 
 
 c.t; 
 
 % a 
 
 . Ferments. 
 Inulin. 
 
 o 
 a 
 
 <n 
 u 
 > 
 
 O 
 4- 
 
 T 
 
 Gives Voges- 
 Proskauer reaction. 
 
 B. coli communis 
 
 
 
 B. acidi lactici 
 
 — 
 
 + 
 
 — 
 
 + 
 
 — 
 
 — 
 
 + 
 
 — 
 
 + 
 
 — 
 
 B. lactis serogenes 
 
 — 
 
 + 
 
 — 
 
 + 
 
 + 
 
 — 
 
 + 
 
 — 
 
 — 
 
 + 
 
 B. cloaca 
 
 + 
 
 + 
 
 4. 
 
 1 
 
 + 
 
 + 
 
 — 
 
 — 
 
 — 
 
 — 
 
 + 
 
 B. proteus 
 
 — 
 
 — 
 
 + 
 
 — 
 
 + 
 
 — 
 
 — 
 
 — 
 
 4- 
 
 1 
 
 — 
 
 B. sulcatus (Gunthal) 
 
 + 
 
 + 
 
 — 
 
 + 
 
 — 
 
 — 
 
 — 
 
 — 
 
 + 
 
 — 
 
 Oxytrens perniciosus . 
 
 — 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 + 
 
 B. coseroba .... 
 
 — 
 
 + 
 
 — 
 
 + 
 
 + 
 
 — 
 
 — 
 
 — 
 
 + 
 
 — 
 
 B. typhosus .... 
 
 + 
 
 + 
 
 — 
 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 B. paratyphosus . 
 
 + 
 
 
 — 
 
 
 — 
 
 + 
 
 — 
 
 — 
 
 — 
 
 — 
 
 B. dysenteriae .... 
 
 + 
 
 + 
 
 
 
 
 
 
 
 
 
 B. paradysenteriaa . 
 
 + 
 
 + 
 
 
 
 
 
 
 + 
 
 — 
 
 — 
 
 common water organism, namely, the B.fiuorescens no?i-Uquefacie?is^ 
 but its fluorescence is characteristic, it produces no gas in the various 
 sugars, and does not coagulate milk. Another micro-organism 
 frequently present in water is B. lactis cerogenes. This is a 
 gram negative rod, non-motile, does not liquefy gelatine, fer- 
 ments lactose, sucrose, and adonit, but does not affect dulcit 
 or inulin. It gives no indol, but does give a Voges-Proskauer 
 reaction. The possible presence of this and other similar 
 micro-organisms in a series of plates set from a water culture 
 should be borne in mind : in no case should an opinion as 
 to identity be formed hastily or from an examination of a 
 
BACTERIOLOGICAL EXAMINATION OF WATER. 12 1 
 
 mere surface or other colony ; each suggestive colony must be 
 fished off on to an agar slope, and the final judgment found only 
 upon a critical analysis of the subcultural reactions in various 
 media. 
 
 For the differentiation of various micro-organisms the table 
 on p. 1 20 may be found useful. It can be extended indefinitely 
 as many organisms found in water are as yet unnamed. It 
 is convenient in practical work to give them a simple serial 
 number. 
 
 The Spirillum cholera is an important organism to those 
 engaged in examining water supplies in tropical countries. It is 
 a small curved micro-organism resembling a comma, usually only 
 one curve is seen, but sometimes two spirilla are attached ends 
 on, and an S-shape produced. It is very motile, having a single 
 flagellum at one end. It does not form spores, but degraded or 
 involution forms are not uncommon, when it appears short and 
 thick like a large coccus. It is markedly aerobic, and grows best at 
 37 C. The colonies on gelatine plates, in twenty-four to forty-eight 
 hours, appear as minute white points, which under a low power show 
 an irregular margin. Later liquefaction of the gelatine occurs. If 
 grown as a gelatine stab, well marked liquefaction is seen on third 
 day as a funnel-like depression. The growth on an agar slope is 
 not characteristic, but on agar plates the surface colonies appear 
 under a low power as very transparent brownish-yellow circular 
 discs. In broth there is diffuse turbidity with a thin pellicle on 
 the surface. Milk remains unchanged ; the growth on potato is not 
 characteristic. Indol and nitrite production is rapid and marked 
 in peptone and salt solution, requiring only the addition of a few 
 drops of pure sulphuric acid to show the so-called " cholera red " 
 reaction. There is no production of gas in the sugar media, but 
 acid is formed in glucose. If a cholera serum is available, 
 agglutination of this spirillum is marked in dilutions from 1-10 
 to 1-120. 
 
 The difficulties of diagnosing the true cholera spirilla in water 
 are often great, and mainly owing to the fact that large numbers 
 of other spirilla may be present which are not necessarily patho- 
 genic. The following is the simplest and most practicable method 
 for the isolation of the cholera spirillum from a water sample. 
 It is based upon the fact that the optimum medium for the growth 
 of the organism is one containing 1 per cent, of peptone and 
 o*5 per cent, of salt, and really consists in converting as much of 
 the suspected water as possible into such a solution, incubating at 
 37 C. for a few hours, and if the spirilla are present isolating 
 them from it. The technique suggested is to make a strong or 
 stock solution containing 10 per cent, of peptone and 5 per cent. 
 
122 WATER. 
 
 of salt; add 10 c.c of this solution to 90 c.c. of the water sample 
 in a sterile flask, and then incubate for from fourteen to twenty 
 hours at 37 C. If cholera spirilla are present they will be found 
 in the scum or pellicle which forms on the surface of the water. 
 Loopfuls from this surface water should be removed and plated 
 out in gelatine or smeared over the surface of solidified agar in a 
 series of Petri dishes. These must then be incubated for another 
 twenty-four hours, and carefully examined for colonies of the 
 suspected spirillum ; any suggestive colonies must be subcultured 
 and judged by their resulting reactions. 
 
 Streptococci. — The hygienic significance to be attached to the 
 presence of these micro-organisms in water has been much 
 debated. They undoubtedly are present in large numbers in all 
 sewage, and can be found, too, if searched for, in the majority of 
 polluted waters. Owing to their minuteness, the delicacy of their 
 colonies, and the not infrequently large volumes of water which 
 must be concentrated for their detection, the routine search for 
 these micro-organisms is the exception rather than the rule in 
 the bacterial examination of water samples. We are disposed to 
 think that this neglect of noting the presence or absence of strep- 
 tococci is unwise, as although the presence of streptococci alone 
 cannot be considered as indicating necessarily a dangerous con- 
 tamination, still, in view of the fact that these organisms tend to 
 rapidly disappear in dilutions of old sewage, their presence in 
 a water supply indicates a recent contamination, but unless 
 they are accompanied by the presence of B. coli this contamina- 
 tion is not necessarily dangerous. On the other hand, their 
 absence does not of itself imply purity and safety ; while their 
 presence, at all events in any number, even in the absence 
 of B. coli and other faecal organisms, is evidence highly sug- 
 gestive of doubt as to the fitness of a given sample for domestic 
 use, and should be a signal for a more critical inquiry into the 
 circumstances. 
 
 The streptococci are small or medium-sized cocci arranged in 
 chains of varying length. They stain with the basic dyes and 
 also by Gram's method. The greater number of strains which 
 we have isolated from sewage and sewage-polluted waters do not 
 liquefy gelatine, but a few varieties do so. On gelatine plates, 
 the surface colonies are granular, circular, and extremely small, 
 with a clear sharp edge, but a few present streaming projections 
 from the margin. In broth, the resulting growth is generally 
 diffuse. Milk is clotted usually by the third day. In peptone 
 and salt solution indol is produced. Glucose and lactose media 
 are acidified, but there is no gas formation. On potato and on 
 agar, the growths are not characteristic. In bile-salt glucose 
 
BACTERIOLOGICAL EXAMINATION OF WATER. 1 23 
 
 broth, there is usually a definite production of acid without gas. 
 Although these are the cultural features of the greater numbei 
 of strains which have come under notice, it must be borne in 
 mind that certain varieties do not conform absolutely to these 
 reactions, the more notable exceptions being an ability to liquefy 
 gelatine and a tendency to form clumps like staphylococci 
 rather than chains. For the isolation of streptococci from 
 water, the concentration of not less than 500 c.c. to 10 c.c. 
 by filtration through a sterile bougie, and subsequent plating 
 in gelatine or on agar, probably constitutes the most satisfactory 
 technique. 
 
 The Significance and Detection of the B. Enteritidis 
 
 Sporogenes of Klein. 
 
 Since Klein first described this micro-organism as being found 
 in all sewages, dirty waters, horse-dung, and earth from manured 
 fields, its presence in or absence from water samples has been 
 deemed a matter of importance. It is an obligatory anaerobic 
 bacillus of considerable size, of variable mobility, staining by 
 Gram's method, and producing under certain conditions oval spores 
 situated in the middle of the rods. On solidified serum it grows 
 well at 37 C, the serum being gradually liquefied, and spores 
 forming about the third day. It grows well also in glucose agar, 
 splitting and tearing up the medium by a copious formation of gas- 
 bubbles. It grows in much the same way in glucose gelatine, 
 slowly liquefying the gelatine. On the surface of an agar slope, 
 the colonies are grey, flat expansions, having no crenations, and 
 the individual bacilli producing no spores. When grown in milk, 
 there is a rapid separation of acid whey and flocculi of casein, 
 much gas formation with a distinct smell of butyric acid. No 
 spores are produced in milk. The separated whey swarms with 
 the bacilli, and is actively virulent if injected into rodents. 
 
 The hygienic significance to be attached to this micro-organism 
 has been much debated. Our experience indicates it to be 
 invariably present in horse-dung, street-sweepings, manure from 
 fields, and in most sewages. Its detection in undoubtedly dirty 
 and sewage-polluted waters is not constant, so much so that we 
 are disposed to doubt whether its importance, as an indicator of 
 sewage in water samples, has not been overrated. Many of the 
 discrepancies as to this micro-organism appear to be due to the 
 fact that there are two other organisms in constant association 
 with filth and decomposing animal matter which present marked 
 resemblances to the B. enteritidis sporogenes of Klein, and with 
 which it seems to have been confused ; these are the B. butyricus 
 
124 
 
 WATER. 
 
 of Botkin and the B. cadaveris sporogenes. The following table 
 (given by Klein) shows the essential difference between these three 
 anaerobic bacilli : — 
 
 B. enteritidis sporogenes. 
 
 Broad cylindrical rods, 
 staining with Gram ; 
 some motile. 
 
 Oval spores situated in 
 the middle of rods. 
 
 Grows well on gelatine, 
 which it slowly liquefies. 
 
 As a stab in gelatine, 
 spherical colonies ap- 
 pear with no filamentous 
 projections. Slow lique- 
 faction. 
 
 On an agar surface, gives 
 circular flat colonies. 
 No spore formation. 
 
 As a stab in agar, little 
 tendency to form lateral 
 branching. Much gas, 
 no spores. 
 
 In milk there is a rapid 
 separation of acid whey 
 and flocculi of casein. 
 Much gas, no spores, 
 but marked smell of 
 butyric acid. 
 
 On serum, free growth 
 with slow liquefaction. 
 Spores are formed. 
 
 Injected into 
 Very virulent. 
 
 rodents. 
 
 B. butyricus. 
 
 Same as B. enteritidis 
 sporogenes. 
 
 Same as B. enteritidis 
 sporogenes. 
 
 Does not liquefy gela- 
 tine, but grows as a 
 mass of convoluted 
 threads. 
 
 As a stab in gelatine, 
 spherical colonies with 
 horizontal filamentous 
 projections. No lique- 
 faction. 
 
 On an agar surface, grey 
 flat colonies with cre- 
 nated edge. No spores. 
 
 in agar, 
 bundles 
 
 As a stab 
 characteristic 
 of threads project later- 
 ally in the depth. Much 
 gas, no spores. 
 
 Same as B. enteritidis 
 sporogenes. 
 
 On serum, grows well, 
 very slow softening. 
 
 Not pathogenic to ro- 
 dents. 
 
 B. cadaveris sporogenes. 
 
 Cylindrical, thin, thread- 
 like rods ; very motile ; 
 staining with Gram. 
 
 Oval spores situated at 
 end of the rods, drum- 
 stick like. 
 
 Liquefies gelatine rapidly, 
 emitting a putrid odour. 
 Free spore formation. 
 
 As a stab in gelatine, 
 rapid liquefaction with 
 putrid odour. 
 
 On an agar surface, 
 thready, branched colo- 
 nies, rapidly forming 
 spores. 
 
 As a stab in agar, free 
 growth of threads along 
 the stab. Much gas, 
 rapid spore formation. 
 
 In milk, much gas formed, 
 also rapid spore forma- 
 tion ; the milk is slowly 
 decomposed. 
 
 On serum, rapid lique- 
 faction, with putrid 
 odour and free spore 
 formation. 
 
 Not pathogenic to ro- 
 dents. 
 
 Experience indicates that, unless care is exercised, it is easy 
 to confuse these micro-organisms one with the other, especially if 
 too much reliance is placed upon the milk reaction. Unless an 
 organism gives all the reactions, particularly that of pathogenicity, 
 it should not be called the B. enteritidis sporogenes, but for 
 practical purposes of water analysis it appears sufficient to identify 
 any one of these three anaerobic bacilli, as the presence of any one 
 of them is significant of pollution. As these spore-bearing organisms 
 occur rarely in large numbers in even dirty waters, the bacterial 
 
BACTERIOLOGICAL EXAMINATION OF WATER. 1 25 
 
 contents of a fairly large volume of the water sample should be 
 used for their detection. This should be about 500 c.c, which 
 must be filtered through a sterile bougie, the organisms arrested 
 on the surface of the filter being then brushed by means of a sterile 
 brush into 10 c.c. of sterile water. Varying proportions of this 
 must be then transferred to tubes of recently boiled sterile milk, 
 the temperature of which at time of inoculation should not exceed 
 8o° C, and then grown anaerobically. The portions may be 
 conveniently distributed into three milk tubes, namely, 6 c.c. into 
 one, and the remaining 4 c.c. equally into two others. Some 
 melted vaseline is then poured over the surface of the milk, in 
 order to exclude air by formation of a covering some half inch in 
 depth. The milk tubes are then placed in a water-bath at 8o° C. 
 for twenty minutes, cooled until the vaseline is well set, and finally 
 incubated at 37 C. for three days. If any of these anaerobic 
 bacilli are present, the typical changes in the milk tubes will be 
 produced. If no result is produced in any of the three tubes 
 inoculated, the water sample may be said to contain less than one 
 spore per 500 c.c. ; if the typical change occur in the one which 
 received the 6 c.c. of filter brushing, but not in the other two, the 
 water is assumed to contain less than one spore per 100 c.c, but 
 one or more in 300 c.c. If the typical change occurs in one or 
 both the other tubes, there is probably one or more spores in each 
 100 c.c. of the sample. If the milk reaction is so atypical as to 
 raise doubts as to whether the organism present is really the B. 
 enteritidis sporogenes, but rather one of its allies, the point can 
 only be settled by careful subculture on the lines indicated. We 
 have never detected any of these anaerobic micro-organisms in a 
 water sample, without finding concurrent evidence of the B. coli 
 and other faecal forms. 
 
 The Interpretation of the Results of a Water Analysis. — 
 This often offers undoubted difficulties, especially to the student 
 and others depending exclusively upon the results of a chemical 
 analysis. The reasons for this are twofold : (1) at best the 
 indications given by the chemical examination are only relative, 
 as the results obtained cannot be interpreted correctly except by 
 reference to local standards ; (2) between an undoubtedly good 
 water and an undoubtedly dirty water there is a considerable range 
 of waters whose chemical analytical features are very ambiguous. 
 There is no general standard which can be fixed for all waters ; 
 the source and its immediate surroundings must be known before 
 a reliable opinion as to the quality of the water can be given. 
 What we need is a carefully constructed series of water standards 
 for individual areas or districts. These standards should relate 
 not only to chemical constituents but to bacterial contents. These 
 
1 26 WATER. 
 
 standards would be of great value in respect of surface waters, 
 where any serious departure from the average would at once 
 suggest cause for critical inquiry as to the why and wherefore. In 
 the absence, then, of district standards or averages, what can be 
 done ? We can depend only upon the following procedures, 
 which we place in their order of value : (1) a careful local inspec- 
 tion for any source of possible pollution ; (2) a bacteriological 
 examination made as soon as possible after collection of the 
 sample ; (3) a chemical analysis. It is rare for a sample of water 
 to yield doubtful results under either the second or third heads 
 when the report under the first has been carefully obtained and 
 found to be free from suggestive features. We, therefore, attach 
 the greatest importance to this matter of local inspection, feeling 
 sure that if carefully and intelligently carried out it affords infor- 
 mation of the greatest value. 
 
 In the preceding pages an attempt has been made to show 
 on what lines a bacterial examination of a water sample should 
 be conducted, and the probable results likely to be obtained in 
 the case of clean and dirty waters respectively. W T e are indis- 
 posed to lay down numerical standards as to the presence of 
 individual bacterial forms in waters : such we know have been 
 formulated, but, in our opinion, they are apt to be used in too 
 routine a manner. Each individual water sample must be judged 
 on its merits with due regard to all the facts. While it is difficult 
 to conceive a properly constructed deep well, and apparently 
 remote from sewage pollution, yielding a water containing any 
 faecal micro-organisms, no matter how large a volume were care- 
 fully examined, it involves less imagination to account for the 
 presence of such forms in comparatively small amounts of surface 
 water, such as are obtained from lakes, ponds, rivers, or shallow 
 wells imperfectly protected. Loath as we are to lay down any 
 arbitrary standard, still for the student and inexperienced we 
 know that this negative attitude is unsatisfactory. Therefore if 
 we express any opinion it is merely as a guide. In this sense we 
 are disposed to say, that the total count on gelatine from a deep- 
 well water sample should not exceed 100 colonies to the c.c. In 
 upland surface and shallow wells, we place the margin of safety 
 at 500 per c.c. But in all these cases the gelatine count should 
 be read in conjunction with the agar plate^ count at 37 C. The 
 latter should not be more than one-tenth of the former in a safe 
 water*. In cases where the agar plates, after incubation at blood 
 heat, are sterile, or nearly so, a deep-well water yielding from 
 500 to 1000 colonies on gelatine might be passed with confidence. 
 The following empirical scheme may be taken as a working 
 guide : — 
 
BACTERIOLOGICAL EXAMINATION OF WATER. \2J 
 
 I. Impure or Sewage-tainted Waters. 
 
 Gelatine plates. — Innumerable colonies, nearly all liquefying, 
 unpleasant odour. 
 
 Agar plates. — Innumerable colonies, chiefly small and grey 
 coloured. 
 
 II. Dirty or Doubtful Water. 
 
 Gelatine plates. — At least 500 colonies to the c.c, chiefly 
 liquefying. 
 
 Agar plates. — About one-tenth found on gelatine. 
 
 III. Clean or Safe Water: 
 
 Gelatine plates. — Few colonies or many, few liquefying types, 
 chromogenic type common. 
 
 Agar plates. — Sterile, or nearly so. 
 
 With regard to the number of B. eoli communis that may be per- 
 mitted or expected to exist in good potable water, we would say, 
 one per c.c. in upland-surface water and waters from shallow wells. 
 In the case of deep wells, say, one per 10 c.c. It must be understood 
 that B. coli communis is much commoner in rural districts than 
 many think, especially in surface waters. The significance under 
 these circumstances is not so great as in the case of wells. Great 
 care must be taken that the isolated organism is the true B. coli 
 communis, and that an error is not made through the presence 
 of other lactose fermentors of quite a distinct nature. As to the 
 chemical results, we would say no more than that the evidence of 
 present or recent animal pollution is especially suggested by high 
 chlorides and oxidized nitrogen in association with marked free 
 and albuminoid ammonia; that of past or remote animal pollution 
 by high chlorides and oxidized nitrogen (not explicable as derived 
 from geological strata) with generally little free and albuminoid 
 ammonia. If the fouling . is chiefly of vegetable origin, we may 
 expect to find high figures for albuminoid ammonia and oxygen^ 
 absorbed in association with low figures for chlorides and oxidised 
 salts of nitrogen. Beyond this general statement we are not 
 prepared to dogmatize ; it may be asked, what constitutes a high 
 figure in respect of these various constituents? The line of 
 demarcation in each case may be taken for practical purposes at 
 the figures already given when explaining the respective analytical 
 procedures advocated. 
 
 As typical of actual analytical results, a few examples of waters 
 from different sources, with expressions of opinion upon them, are 
 given in the following table : — 
 
128 
 
 WATER. 
 
 
 
 
 • 
 H-* 
 
 
 1 
 
 CO 
 
 
 
 T3 
 
 
 t 
 
 "o 
 
 (X 
 
 
 
 
 
 
 
 
 cd 
 
 
 
 CU 
 
 
 
 
 
 
 
 
 CO 
 
 
 
 » 
 
 
 
 
 
 
 
 T3 
 
 
 G 
 
 
 
 
 
 
 
 *• 
 
 
 
 c 
 
 
 D 
 
 
 
 "o 
 
 
 'O 
 
 
 c 
 .5 
 
 
 
 cd 
 
 
 • ^ 
 
 
 
 Dm 
 
 
 G 
 cd 
 
 
 • 
 
 • 
 
 T3 
 
 
 •3 — 
 
 
 
 • »4 
 
 
 . 
 
 . 
 
 O 
 
 c£ 
 
 <£ 
 
 3c£ 
 
 rr, cd 
 
 Oh 
 
 
 S o 
 
 
 
 JJ 
 
 
 cu 13 
 
 Cm CJ 
 
 cd ^ ,5 
 
 G *-■ cd 
 t) CO 
 
 ci 
 
 
 a 
 
 co 
 
 G 
 
 cd 
 co 
 G 
 
 4? 
 
 -2 o 
 
 Q 
 
 CO 
 
 cd 
 
 CO 
 
 cd 
 
 G 
 
 J? 
 
 cd 
 
 cd 
 co 
 
 G 
 
 
 
 
 
 
 
 
 
 ^—^— s 
 
 
 N ^— - A — * 
 
 y^-^— *- 
 
 
 
 CO 
 
 CO 
 
 co 
 
 co 
 
 co 
 
 CO 
 
 ■JTJ 
 
 CO 
 
 t/5 C/3 
 
 cn 
 
 
 
 a 
 
 g 
 
 a 
 
 e 
 
 s 
 
 g 
 
 a 
 
 a 
 
 a a 
 
 a 
 
 | 
 
 
 co 
 
 CO 
 
 >H 
 
 )-> 
 
 M 
 
 U 
 
 
 )H 
 
 CO hi 
 
 hi 
 
 3 
 
 
 '3 
 
 • t-l 
 
 G 
 
 •s 
 
 v2 
 
 *s 
 
 ^ 
 
 s 
 
 ^ 
 
 *G O 
 
 G Cm 
 
 c2 
 
 "Si 
 
 T3 
 
 cd 
 
 cd 
 
 
 
 
 
 
 
 cd 
 
 
 G 
 
 tx 
 
 tX 
 
 CU 
 
 V 
 
 o 
 
 <u 
 
 
 CU 
 
 tO 4J 
 
 CU 
 
 3 
 
 l-l 
 
 l-l 
 
 t/3^, 
 
 U3 
 
 tJ3 
 
 W 
 
 
 tx 
 
 O cd 
 
 ox 
 
 .23 
 
 o 
 
 O ■£ 
 
 ° G 
 
 5 G 
 
 rt 
 
 cd 
 
 aS 
 
 
 cd 
 
 cd 
 
 Ut CO 
 V V 
 
 <*; 
 
 d 53 
 
 CD 1) 
 
 ^^ 
 
 ^^ 
 
 *y. 
 
 D ^ 
 
 ^"2 
 
 cu 'O' ^ T3 
 
 ^'S 
 
 z. Z 
 
 ■ »h 
 
 c/) 'i . 
 
 tX co 
 
 <u ^ 
 
 cu G 
 
 cu G 
 
 CU G 
 
 bij G 
 
 CU c 
 
 OX G cu G 
 
 <U G 
 
 u 
 
 03 
 
 o* 
 o 
 
 rt H 
 
 rt ^ 
 
 CO JJ 
 
 CO p 
 
 co 3 
 
 co S 
 
 cd 3 
 
 co 3 
 
 cd 3 co 3 
 
 co 3 
 
 i. *H 
 
 •* G 
 
 CU 
 
 CO 
 
 cu 
 
 CO 
 
 1m 
 
 O & 
 
 ,o 
 
 O **5 
 
 o "8 
 
 ^v2 
 cu 
 
 CO 
 
 O 
 
 co ^5 
 
 ,o 
 
 
 pq 
 
 Z 
 
 ^ 
 
 ^ 
 
 » 
 
 £ 
 
 ^ ) 
 
 
 
 
 
 
 
 o 
 
 n 
 
 o 
 
 o 
 
 o o 
 
 "-> 
 
 •paqaosqB 
 
 u-> 
 
 o 
 
 HH 
 
 VO 
 
 
 ON 
 
 CM 
 
 NH 
 
 Tj" 
 
 oo <o 
 
 n 
 
 uzTS.ixQ 
 
 1-4 
 
 IN 
 
 >-« 
 
 O 
 
 f 
 
 CN 
 
 )-< 
 
 r 1 
 
 O 
 
 — o 
 
 o 
 
 
 b 
 
 b 
 
 b 
 
 b. 
 
 b 
 
 b 
 
 b 
 
 o 
 
 b 
 
 b b 
 
 b 
 
 
 *o 
 
 VO 
 
 cn 
 
 '+ 
 
 ON 
 
 n 
 
 o 
 
 ■<^ 
 
 rn 
 
 rf 
 
 HH 
 
 •BIUOUIUIB 
 
 o 
 
 8 
 
 o 
 
 o 
 
 o 
 
 ^4 
 
 o 
 
 o 
 
 o 
 
 ro O 
 
 o 
 
 piouiiunqiy 
 
 o 
 
 p 
 
 o 
 
 o 
 
 p 
 
 o 
 
 p 
 
 p 
 
 P P 
 
 p 
 
 
 b 
 
 b 
 
 b 
 
 b 
 
 b 
 
 b 
 
 b 
 
 b 
 
 b 
 
 b b 
 
 b 
 
 
 VO 
 
 
 vr> 
 
 o 
 
 l-H 
 
 ro 
 
 On 
 
 00 
 
 
 00 ii 
 
 
 
 o 
 
 ■— 4 
 
 l-O 
 
 HH 
 
 NM 
 
 o 
 
 8 
 
 HH 
 
 — < 
 
 O i 
 
 N 
 
 •BiUOUIUIB 33i^ 
 
 o 
 
 • t-H 
 
 O 
 
 O 
 
 O 
 
 O 
 
 o 
 
 '2 
 
 o o 
 
 O 
 
 
 b 
 
 
 b 
 
 b 
 
 b 
 
 b 
 
 b 
 
 b 
 
 
 b b 
 
 b 
 
 
 co 
 
 
 
 
 
 
 
 CO 
 
 
 
 
 •sajuji^i 
 
 V 
 
 cj 
 
 cd 
 
 g 
 
 G 
 
 G 
 
 G 
 
 a 
 
 G 
 
 CJ 
 CJ 
 
 cd 
 
 r— 1 
 
 i-M —1 
 
 •-^ 
 
 G 
 
 G G 
 
 G 
 
 
 ~h> 
 
 
 
 
 
 
 
 -i-i 
 
 
 
 
 •u33oj;iu sncujiu 
 
 
 
 n 
 
 fO 
 
 o 
 
 vO 
 
 
 On 
 
 
 ON 
 
 
 PUBOUIISJ 
 
 «0 
 
 t~» 
 
 H 
 
 o 
 
 o 
 
 i— t 
 
 vO 
 
 fO 
 
 00 
 
 W O 
 
 n 
 
 * 
 
 H 
 
 Ml 
 
 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o o 
 
 n 
 
 
 U-i 
 
 o 
 
 o 
 
 00 
 
 CN 
 
 o 
 
 o 
 
 o 
 
 o 
 
 ON O 
 
 >o 
 
 •sapuopQ 
 
 CN 
 
 "d- 
 
 CN 
 
 CN 
 
 N 
 
 N- 1 
 
 CO 
 
 ON 
 M 
 
 HH 
 
 
 HH 
 
 
 V 
 
 o 
 
 SX • 
 
 a 
 
 • 
 
 T3 
 
 • 
 
 
 • 
 
 
 
 • 
 
 
 
 •iM 
 
 |M 
 
 • 
 
 CU 
 CJ 
 
 cu 
 
 
 • 
 
 
 CJ 
 
 • 
 
 
 O 
 
 S 
 
 S3 
 > 
 
 o 
 
 o 
 
 • fMJ 
 
 CO . 
 
 T3 
 
 • 
 
 cu 
 
 O 
 
 )- 
 
 Gu 
 
 
 
 • 
 
 
 hi 
 
 cd 
 
 «° • 
 
 'O O 
 
 13 *" t3 
 
 3- g 
 
 CO . 3 
 
 cd h, i-M 
 
 • 
 
 G 
 
 M 
 V 
 
 o 
 
 c 
 
 rt 
 
 </) 
 
 E 
 
 3 
 U 
 h 
 
 o . 
 
 bx 
 cd 
 
 CU 
 (A 
 
 F— 4 
 
 cd 
 
 • *-< 
 
 *— « 
 
 o 
 
 • *H 
 
 C . 
 cd 
 
 V 
 
 > 
 
 o • 
 cj 
 
 • 
 
 CD 
 
 o 
 
 4-J 
 
 o 
 a. 
 
 13 
 
 c 
 u 
 
 hi 
 
 o 
 
 o 
 
 S 
 
 w 
 CU 
 
 • 
 • 
 
 l-l 
 cd 
 
 hi 
 
 cd 
 
 s 
 
 _o 
 
 *-< 
 
 CJ 
 CJ 
 4^ 
 
 O 
 hi 
 
 Oh 
 O 
 
 G 
 
 C 
 
 o 
 
 13 5* 
 •^ CO 
 
 T3 
 cd 
 O 
 
 tx 
 
 c 
 
 "a, ' 
 o 
 
 cd 
 
 s 
 
 o 
 
 <u 
 
 o 
 
 u 
 
 -— ' 
 
 o 
 
 hi 
 
 a 
 hi 
 
 a 
 
 hi 
 
 G 
 
 CU 
 
 CO 
 
 Dh 
 
 O 
 o 
 
 h 
 
 3 
 
 co 
 
 O 
 
 o 
 
 
 
 
 cd 
 
 13 
 
 i— * 
 
 13 
 
 Gh cd 
 cu — 
 
 .£ is 13 
 
 cd 
 
 a 
 
 
 £ G 
 
 o -^ 
 
 tX 
 
 
 ^ 
 
 o 
 
 CU 
 
 u 
 
 
 £ 
 
 o 
 
 "o ^ 
 
 CX 
 
 
 
 G 
 
 
 
 ^3 
 
 43 
 
 1? 
 
 G 
 
 ■ -^ 
 
 )-■ 
 
 a. 
 
 CU 
 
 <u 
 
 Id 
 hG 
 
 co Q 
 
 G 
 
 "hi 
 
 
 CO 
 
 CO 
 
 Q 
 
 Q 
 
 CO 
 
 CO 
 
 CO 
 
 Q 
 
 CO 
 
 CO 
 
 
 *H 
 
 M 
 
 to 
 
 Tf 
 
 vr> 
 
 VO 
 
 t-o 
 
 00 
 
 ON 
 
 o 
 
 2 
 
CLASSIFICATION OF FOOD. 1 29 
 
 CHAPTER III. 
 
 FOOD. 
 
 The Classification, Nature, and Uses of Food Stuffs. — We may 
 define the word food as including everything we take into our 
 bodies which either directly or indirectly goes to the growth and 
 repair of the body or to the production of energy or functional 
 activity in any form. This definition necessarily includes not 
 only all the ordinary articles consumed in eating and drinking, 
 but also water and air. Since, however, the taking in of air into 
 our lungs is mainly an involuntary act, it is customary not to 
 include air and its constituents taken into our bodies by the lungs 
 as foods, but to strictly limit the term food to substances taken 
 by the mouth into the digestive tract. 
 
 It is convenient to speak of the various substances which 
 constitute food as proximate principles, because, consisting as they 
 do of carbon, hydrogen, oxygen, and nitrogen, combined more or 
 less into highly complex bodies, they really are elementary con- 
 stituents or proximate principles of the human organism. These 
 elementary or proximate principles may be conveniently classified 
 as follows : — 
 
 1. Proteins. 
 
 2. Fats. 
 
 3. Carbohydrates. 
 
 4. Mineral salts. 
 
 5. Vegetable acids. 
 
 6. Vitamines or accessory principles. 
 
 The simplest division of the various constituents of food is 
 into the nitrogenous and the non-nitrogenous, or those which 
 contain nitrogen and those which do not. The proteins alone 
 contain nitrogen ; but it is possible and probable that the 
 vitamines have also a nitrogen basis. The greater part of our 
 body is made up of nitrogen containing substances. A large 
 amount of nitrogen in the form of urea, uric acid, and other 
 substances, is being lost daily from our bodies by the urine; and 
 to repair this loss, a daily intake of nitrogenous food is required. 
 The only form of nitrogen food which the body can make use of 
 is protein, with the vitamines as accessory agents. The nitro- 
 genous content of the vitamines is at present not known. A plant 
 equally needs nitrogen, but this it obtains from the ammonia 
 
 F 
 
130 FOOD, 
 
 and nitrates of the soil, which are much simpler bodies than 
 proteins. 
 
 All proteins are composed of carbon, hydrogen, oxygen, 
 nitrogen, and sulphur, with occasionally a little phosphorus. Their 
 general percentage composition may be taken as being : nitrogen, 
 1 6 parts ; carbon, 54 parts; oxygen, 22 parts ; hydrogen, 7 parts; 
 and sulphur, 1 part. The proteins, when regarded as foods, are 
 divisible into two great groups, according to their nutritive value. 
 The more nutritious one is the group of true proteins, consisting 
 of albumin, myosin, glutin, casein, legumin, and peptones; in 
 them, the proportion of nitrogen to carbon is nearly as 2 is to 7. 
 The other, or less nutritious, group is sometimes called the albu- 
 minoid group ; its members include substances obtained only from 
 animals, such as gelatin, chondrin, ossein, and keratin ; in them, 
 the proportion of nitrogen to carbon is as 2 is to 5-^. 
 
 Albumin constitutes the essential constituent of that substance 
 which, called by physiologists protoplasm, really is the physical 
 basis of life. In its most familiar form, we find it as egg albumin, 
 or that which makes up nearly the whole of the white and a third 
 of the yolk of an egg. A similar body is serum albumin, or the 
 chief solid constituent of blood serum. 
 
 Myosin, or muscle albumin, is present largely in muscle, from 
 which it can be obtained by first washing out all the serum, then 
 dissolving the mass in a 10-per-cent. solution of common salt, 
 and dropping the semi-solid substance into a vessel containing 
 distilled water, in which it forms a flocculent deposit. 
 
 Glutin is an insoluble protein obtained from the seeds of most 
 of the cereals. If a little flour be placed in a piece of muslin 
 and a stream of water be allowed to run on it, as the water 
 leaves the paste it will be quite milky, and if collected, the white 
 powder which makes it milky will settle at the bottom of the 
 vessel. The powder thus obtained from the flour is starch. 
 The substance which remains in the muslin is not at all like 
 flour or dough, but is a sticky substance, and is really nearly pure 
 glutin. 
 
 The three foregoing substances have one common feature, 
 namely, that they are coagulated by heat ; and when so coagulated, 
 as in cooking, they are not dissolved by either water or dilute 
 acids and alkalies, but are readily dissolved and digested by the 
 gastric juice of the stomach. 
 
 Casein is the nitrogenous solid present in milk, familiar to us 
 all as the curd which forms when an acid is added to milk, 
 
 Legumin is a protein very much resembling casein, but present 
 chiefly in the seeds of beans and peas. 
 
 Peptones and albumoses are forms of proteins very closely 
 
CLASSIFICATION OF FOOD. 131 
 
 related one to another, and though probably widely distributed in 
 vegetables and plants, are chiefly formed by the action of pepsin 
 upon ordinary proteins. The albumoses are, strictly speaking, 
 precursors or bodies formed before peptones during digestion of 
 proteins. The peptones are remarkable for their extreme diffusi- 
 bility and ready absorption by the alimentary canal. Owing to 
 their easiness of digestion, these forms of protein are now largely 
 given in the various kinds of partly artificially digested foods for 
 the sick, though it must be remembered that they do not possess 
 the same nutritive value as the ordinary proteins of food. Both 
 casein and the peptones have the common characteristic of not 
 being coagulated by heat. 
 
 As closely allied to the foregoing may be mentioned syntonin % 
 or acid albumin, which exists in some meats, and also alkali 
 albumin. These are formed by the action of dilute acids and 
 alkalies on the ordinary proteins, and are not precipitated from 
 solutions by boiling. 
 
 The albuminoids, such as gelatin, chondrin, etc., are bodies 
 closely resembling the albumins, but probably not existing as such 
 in the tissues of the body, but only obtained from them by pro- 
 longed boiling. These bodies are easily dissolved in hot water, 
 and yield more or less the same products after digestion as the 
 proteins, but experience shows that life cannot be sustained when 
 this is the only nitrogenous matter taken as food. 
 
 For practical purposes, it can be said that the nutrition of the 
 nitrogen containing tissues means the nutrition of the body, and 
 that the main part of the protein substances taken in as food is, at 
 least for a time, stored up in the body generally, to be used up 
 as required by the tissues for their repair and growth, and, in a 
 limited sense, also as a source of some of the fat of the body and 
 of the glycogen found in the muscles and liver ; any excess over 
 these needs being at once metabolized and eliminated. From 
 this it is evident that the proper supply of the protein food stuffs 
 is of the first importance, though an excess of protein food throws 
 an excess of work on the nitrogenous tissues. The natural law 
 seems to be that to preserve health the nitrogen taken must 
 equal that destroyed. 
 
 Fats. — These contain carbon, hydrogen, and oxygen, but no 
 nitrogen. The proportion of oxygen in them, however, is in- 
 sufficient to combine with all the hydrogen present so as to form 
 water. When taken as food, the fats not only repair or renew 
 the fatty tissues, but yield energy and heat, owing to their oxida- 
 tion into carbon dioxide and water. In addition to this, they 
 help in the proper digestion of the other foods, possibly owing 
 to their power or influence in promoting the flow of bile and 
 
132 FOOD. 
 
 the pancreatic juice. When consumed as food, the fats are not 
 acted upon by either the saliva in the mouth or by the gastric 
 juice of the stomach, but reach the small intestine more or less 
 unchanged, where they become emulsified by the bile and pan- 
 creatic juice, and in the emulsified state are readily absorbed 
 by the lacteal vessels. Fats are found in the majority of diets of 
 all nations, and by those living in very cold countries, the amount 
 consumed is very large. When hard work is being performed, 
 an increase of fatty food is demanded. 
 
 Carbohydrates. — This is a large group, and embraces all the 
 various starches and sugar, also cellulose and gum. Like the 
 fats, these contain no nitrogen, but only carbon, hydrogen, and 
 oxygen ; these two latter elements exist in sufficient proportion to 
 form water, hence their name, " carbohydrates." In the main, 
 the carbohydrates are derived from the vegetable world, though 
 lactose, a kind of sugar, is found in milk, and glycogen, a form of 
 starch, exists in the liver. 
 
 The starches represent a large class of foods, and constitute 
 the chief portion of the seeds of the various cereals and potatoes. 
 Starch combines with iodine to form a blue colour, constituting 
 thereby a simple test for its presence. In cold water or alcohol, 
 starch is insoluble, but at about 180 F. water causes the granules 
 to burst and swell out. Heat and dilute acids convert starch 
 into a gum-like substance, called dextrine, and, if carried further, 
 into grape sugar. A similar action is produced upon starch by 
 the saliva and pancreatic juice. Starch, represented by the 
 formula C 6 H 10 O 5 under the influence of these juices, takes up a 
 molecule of water H 2 and becomes C 6 H 12 G , or grape sugar ; this, 
 on being taken up by the blood, is carried along the portal vein 
 to the liver, where it is transformed into glycogen or liver starch, 
 to be subsequently supplied to the system as the needs of the 
 body demand. When exposed to the action of diastase, which is 
 a peculiar ferment existing in all germinating seeds during growth 
 (malted barley, for example), starch is converted into another 
 form of sugar called maltose, CioH L «O n ,H 2 0, a substance 
 isomeric with lactose. 
 
 The sugars belong practically to one or other of two kinds, 
 namely, the sucrose or cane-sugar variety, and the glucose or 
 grape sugars. 
 
 Cane sugar, or sucrose, is the ordinary sugar of commerce, 
 extracted chiefly from sugar cane. It is a crystalline body, not 
 soluble in either absolute alcohol or ether, though freely so in 
 weak alcohol ; in water, its solution is thick and syrupy. Cane 
 sugar is represented by the formula C 12 H ffi O u , and to its group 
 belong maltose and lactose. The former is a low form of sugar, 
 
CLASSIFICATION OF FOOD. 133 
 
 the final product of the action of diastase on starch. Lactose, 
 CjoHojOxo, or sugar of milk, is a variety of sugar found only in the 
 milk of the mammalia. It is only partially soluble in either hot 
 or cold water, and not directly susceptible of alcoholic fermentation 
 except under the action of weak acids which convert it into grape 
 sugar. In the presence of any decomposing proteins, lactose is 
 transformed into lactic acid. One of the most remarkable 
 features connected with the sugars is their power of deflecting a 
 ray of polarized light to either the right or left. Cane sugar has 
 a specific rotating power of 73°*8 to the right; maltose has a 
 similar power of 1 5 5 to the right; while lactose has an action 
 on polarized light in the same direction of 6i Q, 5. 
 
 Grape sugar, or glucose, also called dextrose, or starch sugar, 
 exists ready formed in grapes and other fruits, but is also made on 
 a large scale from starches either by treating them with dilute 
 acids or by the action of malt ; in fact, grape sugar is the first 
 product during the fermentation of either cane sugar, milk sugar, 
 or starch. When a solution of cane sugar is boiled with dilute 
 mineral acids, the sugar is split up into two glucoses. One of these 
 rotates polarized light to the right, and is hence called dextrose ; 
 the other rotates it to the left, and hence called levulose. This 
 mixture of dextrose and levulose is often called invert sugar, 
 because the polarization of light is the opposite of that of cane 
 sugar, for although dextrose or glucose rotates to the right some 
 57°'6, and levulose to the left, yet the latter rotates so much more, 
 namely, io8°'8, that the combined solution polarizes distinctly to 
 the left. Glucose or dextrose is soluble in both water and 
 dilute alcohol, and is directly broken up or fermented by yeast 
 into alcohol and carbon dioxide. 
 
 Among carbohydrates must be included cellulose and pectose. 
 Cellulose constitutes the chief framework of plants; it is quite 
 insoluble, and without any dietetic value. In a similar way, 
 Pectose, or vegetable jelly, is found in various ripe fruits, being 
 really a later stage of the insoluble body present in most unripe 
 fruits, and known as pectin. Its precise composition is unknown. 
 
 In their physiological use, the carbohydrates closely resemble 
 the fats and oils ; being directly used in contributing to the 
 maintenance of animal heat and the production of force or 
 energy as well as the formation of fat. They, however, differ 
 from the fats in that the amount of them consumed as food is 
 proportional to the quantity of CO a excreted; with fats this is 
 not so. Performing as they do in the body similar functions, 
 it has been surmised that fats and carbohydrates might be 
 mutually interchangeable as articles of diet. On this point, 
 although the evidence is not very precise, the general consensus 
 
134 Foot). 
 
 of opinion is that they are not wholly interchangeable, though 
 perhaps practically so, as instanced by the fact that, owing to their 
 relative cheapness, carbohydrates largely replace, but not com- 
 pletely, the fats in the diets of the poor. A certain degree of 
 health can be maintained on a diet of proteins, fats, salts, and 
 water, but the absolute withdrawal of fats and a bare substitution 
 of carbohydrates for them rapidly leads to a loss of vigour and 
 health. The truth probably lies in the acceptance of an admix- 
 ture of both fats and carbohydrates in the diet. 
 
 Mineral Salts. — Among the mineral salts which constitute a 
 part of the proximate principles of food must be included 
 chloride of sodium or common salt, the phosphates of lime, potash, 
 soda, and magnesium, along with small quantities of sulphates, 
 and possibly iron. These, in their various and respective ways, 
 are essential for the repair and growth of all parts of the body. 
 The uses of the chlorides, as typified by common salt, are very 
 important. The complete withholding of ordinary salt from food 
 leads to rapid disease, ard even death. The chlorides generally 
 keep in solution the globulins of the blood and other fluids, while 
 at the same time are the source of the hydrochloric acid of the 
 gastric juice, and materially aid in the solution of albumin. The 
 ohosphat.es of lime, potash, and magnesia contribute, especially in 
 the young, to the formation of bone ; while iron forms an impor- 
 tant part of the haemoglobin of the red blood corpuscles. 
 
 If we remember that 64 per cent, of the body consists of water^ 
 the need of it is not difficult to understand. Though a portion 
 of it is obtained by the oxidation of the hydrogen in the tissues, 
 still the greater part is derived from that taken in as food. In 
 the body itself, water serves chiefly for the solution and convey- 
 ance of food to different parts of xhe system, for the excretion of 
 effete products, for the equalization of heat by evaporation, both 
 from the lungs and skin, as well as for the regulation of all the 
 chemical and mechanical functions of the body. 
 
 Vegetable Acids. — These, though not strictly speaking foods, 
 play so important a part in preserving the health of man that they 
 demand some considerable notice. The chief among them are 
 tartaric, citric, malic, oxalic, and acetic acids. Tartaric acid, 
 C 4 H 6 6 , exists largely in grape juice chiefly as the acid tartrate of 
 potassium ; Citric acid, C 6 H 8 7 , is found in oranges, lemons, and 
 gooseberries; Malic acid, C 4 H 6 5 , is met with in fruits belonging 
 to the rose order, such as apples and pears ; Oxalic acid, C0H2O4, 
 is present largely in rhubarb and sorrel ; Acetic acid, C2H4O0, con- 
 stitutes the active element in vinegar. Except it be the latter, all 
 these vegetable acids contain more than sufficient oxygen to con- 
 vert all their hydrogen into water. These acids exist mainly in 
 
CLASSIFICATION OF FOOD. 1 35 
 
 fresh fruits and vegetables, either as free acids or in combination 
 with alkalies as alkaline salts, and, when taken into the body, form 
 carbonates, which exercise a controlling influence in preserving 
 the alkalinity not only of the blood but other fluids ; they also 
 furnish a small amount of energy and heat by oxidation. Their 
 absence for any length of time from any dietary leads to a 
 disturbance of nutrition. It is possible that some of these acids 
 are not only derived from fruits and vegetables, but also in a 
 small degree from the splitting up of carbohydrates, so that even 
 the latter, in an indirect way, help in maintaining the alkalinity 
 of the blood and other animal fluids. 
 
 Vitamines. — Tnese are certain accessory principles present 
 in all fresh food stuff or in food which has not become degraded 
 or dried excessively, or exposed to high temperatures. Their 
 chemical composition is unknown, but it is probable that they have 
 a nitrogen basis. Their function appears to be to act as activators 
 or stimulators for the essential physiological changes in the body 
 following the ingestion of food and its proper conversion into the 
 various tissues and liquids which go to the make-up and main- 
 tenance in health of our body. Fresh milk is particularly rich in 
 vitamines, and so are most of the vegetable foods such as rice 
 and potatoes, and also most of the fruits. The vitamines appear 
 to be concerned intimately in nutrition, and for this reason may be 
 called accessory growth substances. Their absence from dietaries 
 is associated with the production of what have been termed 
 deficiency diseases, such as rickets in children, scurvy, beri-beri, 
 polyneuritis and a certain sloughing and ulceration of the cornea 
 of the eye in advanced conditions of starvation or mal-nutrition. 
 Three groups of vitamines are recognized. One is a fat soluble 
 substance and present in all fresh animal fats, but absent from 
 most vegetable oils. This vitamine is not readily affected by 
 heat, but sensitive to oxidation, is present largely in fresh normal 
 milk, and appears to play a large part in the prevention of 
 rickets. The other two varieties of vitamines are both soluble in 
 water. One of them exists largely in the inner coat of rice 
 and is the anti-neuritic factor which plays so large a part in the 
 prevention of beri-beri and the polyneuritis of the tropics. It 
 stands desiccation, but is susceptible to a temperature of 70 C. 
 The other water-soluble vitamine is the anti-scorbutic factor. It 
 is present in milk and in the juice of many fruits, especially in 
 limes from Sicily and the Mediterranean, less so in other 
 varieties, in oranges and other fruits. The vitamine is tolerant 
 of drying slowly and of a temperature to 70 C. In the past, 
 much of the action which we now recognize as due to the 
 presence of vitamines was attributed wrongly to the vegetable 
 
136 FOOD. 
 
 acids and fruit juices. Quantity of vitamines is as essential as 
 quality, but at present we cannot dogmatize as to dosage. 
 
 The Nutritive Value of the Food Stuffs. — In the preceding 
 pages we have learnt the part which the various food stuffs play 
 when taken into the body; it is now necessary to learn their 
 nutritive value. To begin with, if we lift a weight by our 
 hands, muscular force is employed in the act, and the energy 
 evolved in this or any other muscular action must have its 
 origin or source in something. As a matter of fact, the energy 
 so evolved has its source in the material which has been supplied 
 to the body in the form of food. Every process of our bodies, 
 no matter whether it be the moving of a hand or a foot, the 
 beating of our heart, or the secretion of saliva, is attended with 
 some manifestation of energy, and this energy is shown in one 
 or other of two forms, namely, either mechanical labour or heat. 
 Just as coal is burnt on the fire so food is burnt in our bodies. 
 True, it is burnt more slowly and with the production of no 
 severe heat, but the process is the same with the same result, 
 warmth. Further, the food produces power for all our actions, 
 and the amount of power at our command depends upon the 
 energy or fuel value which our food gives. The problem, how- 
 ever, is not of a very simple nature. In the case of the water 
 and mineral salts of the food, their nutritive value is not difficult 
 to ascertain, because they are simple bodies, and do not undergo 
 any very great chemical change in the body: The nutritive 
 value of the proteins, fats, and carbohydrates, however, is not 
 so easy to determine, because not only are they complex bodies 
 in themselves, but, moreover, undergo complicated and ill-under- 
 stood changes within the body ; their nutritive value, therefore, 
 cannot be very accurately expressed, 
 
 The various statements as to the potential energy possessed 
 by food stuffs are synonymous with and proportional to the heat 
 yielded by definite quantities during their combustion under definite 
 conditions. The standard measure of heat is the Calorie. This 
 heat or food unit is the amount of energy required to raise the 
 temperature of 1 kilog. (or 1 litre) of water i° C., or, which is the 
 same thing, 1 lb. of water 4 F. This heat unit corresponds to 
 425,500 units of work, which are grammetres; or a weight of 
 425*5 kilogs., if allowed to fall from a height of 1 metre, would 
 by its concussion produce as much heat as would raise the 
 temperature of 1 litre of water i° C. In other words, one 
 Calorie, as a measure of the work derivable from a food stuff, is 
 equal to 425*5 kilogrammetres. 
 
 According to the English system the heat unit is the amount 
 of energy required to raise the temperature of a pound of water 
 
NUTRITIVE VALUE OF FOOD. 
 
 137 
 
 i° F., and will, if manifested as a mechanical force, raise 772 lbs. 
 a foot high, or, what amounts to the same thing, 1 lb. 772 feet 
 high. Thus the dynamic or mechanical equivalent of one degree 
 of heat on the Fahrenheit scale is said to be 772 foot-pounds. 
 Adopting the Centigrade scale, then the mechanical equivalent 
 of i° C, or i°'8 F., will be 1389 foot-pounds; that is, the energy 
 which will raise the temperature of 1 lb. of water i° C, or i°*8 F., 
 will be capable, as a motive power, of raising 1 lb. in weight 1389 
 feet high. In England the amount of work done is commonly 
 expressed as foot-tons or tons lifted 1 foot ; while in France it is 
 often expressed as kilogrammetres or kilogrammes lifted 1 metre. 
 
 Units of work, expressed according to the continental system 
 as gramme-metres, can be converted into foot-pounds by multi- 
 plying them by 0*007233, and into foot-tons by dividing by 311,000. 
 Similarly, kilogrammetres are converted into foot-pounds by 
 multiplying by 7*233, and into foot-tons by dividing by 311 ; also 
 Calories into foot-tons by multiplying by i'36. 
 
 Applying this principle, that as heat production is related to 
 the amount of chemical action ensuing, so likewise is mechanical 
 power production, we find that as a measure of the utility of 
 food, the value of the various food principles as mechanical 
 power producers will correspond with their value as heat pro- 
 ducers. Those food principles, which by oxidation give rise to 
 the greatest amount of heat, will, of course, theoretically have the 
 greatest capacity for the production of working power; that is, 
 will possess the greatest potential energy. This theoretical 
 potential energy is not only different in the case of each class of 
 food stuff, such as protein, fat, and carbohydrate, but differs also 
 in different foods of each of these classes. In the case of many 
 food stuffs, their actual value in respect of capacity for heat pro- 
 duction has been determined experimentally, and expressed in 
 relation to the performance of work. 
 
 The following table gives the number of Calories yielded by 
 the complete combustion of 1 pound of some common articles 
 of food : — 
 
 Dripping 4 l %5 
 
 Lard 4006 
 
 Butter 3600 
 
 Margarine .... 3560 
 
 Suet 3425 
 
 Chocolate ..... 2853 
 
 Bacon, 16 % bone . . 2275 
 
 Sausage . . . . . 2130 
 
 Pork 1870 
 
 Sugar 1822 
 
 Biscuit (unsweetened) . 1S00 
 
 Cheese , 1777 
 
 Oatmeal ..... 1732 
 
 Ham 1670 
 
 Macaroni 1660 
 
 Flour (wheat) . . . 1650 
 
 Cornflour 1648 
 
 Tapioca ..... 1642 
 
 Arrowroot .... 1642 
 
 Rice 1631 
 
 Beans, peas, lentils . . 1626 
 
 Fat beef, no bone . . 1620 
 
n 
 
 8 
 
 FOOD. 
 
 Maizemeal 
 
 Currants and raisins 
 
 Honey . 
 
 Figs "... 
 
 Dates . 
 
 Mutton, no bone 
 
 Tinned beef . 
 
 Beef, average, no 
 
 Bread . 
 
 Cream . 
 
 Beef, 1 8 % bone 
 
 Mutton, 20 % bone 
 
 Sardines 
 
 1609 
 
 1536 
 1520 
 1470 
 1420 
 1306 
 1280 
 1218 
 1200 
 1093 
 1000 
 
 993 
 952 
 
 Jam or marmalade 
 
 Salmon 
 
 Eggs . 
 
 Liver . 
 
 Rabbit 
 
 Herrings 
 
 Potatoes 
 
 Milk, I pint 
 
 Tripe . 
 
 Cod 
 
 Carrots 
 
 Turnips 
 
 Cabbage 
 
 945 
 730 
 624 
 
 580 
 
 556 
 
 438 
 
 395 
 
 3i5 
 270 
 
 228 
 
 15S 
 
 127 
 
 124 
 
 The above figures refer, of course, to laboratory experiments, 
 involving a complete combustion of the food stuff, but in the body 
 it is practically only the fats and carbohydrates which are com- 
 pletely burnt; while the proteins are not metabolized beyond the 
 stage of urea, which we know escapes in the urine. Rubner has 
 shown that, if allowance is made for such incompletely oxidized 
 products, the heat value of 1 grm. of the chief alimentary prin- 
 ciples, when taken into the body, is as follows : — 
 
 Calories. 
 
 Protein 4*1 
 
 Fat 9-3 
 
 Carbohydrates 4' I 
 
 If we know what is the percentage composition of any given 
 food in terms of protein, fat, and carbohydrates, it is quite easy 
 to find the total Calories yielded by 100 parts of the food in 
 question. The Calorie value of statements made in ounces is 
 readily obtained by multiplying by 28*34, or, in other words, an 
 ounce of protein or carbohydrate yields 116 Calories and an ounce 
 of fat yields 263*5 Calories. 
 
 The following table shows the percentage composition of the 
 more ordinary articles of food in terms of protein, fat, carbo- 
 hydrates, salts, and water : — 
 
Arrowroot 
 
 Bacon (Letheby) ...... 
 
 Barley meal (de Chaumoni) . 
 Barley pearl (Church) .... 
 
 Beef, best quality (Konig) 
 Beef as supplied to army 
 
 Beef, salted 
 
 Beef, corned or Chicago (Parkcs) 
 Beetroot (Konig) . ... 
 
 Biscuits 
 
 Bread (Rubner) 
 
 Bread, average wheaten .... 
 Butter, English fresh (Bell) . 
 Butter, very best (Bell) .... 
 
 Butter, salt (Bell) 
 
 Butter, highly salted (Bell) . . . 
 
 Cabbage (Konig) 
 
 Cabbage, Brussels sprouts 
 
 Carrots (Konig) 
 
 Cheese, Dutch (Bell) 
 
 Cheese, Single Gloster .... 
 Cheese, poor quality (Bell) . 
 
 Cream (Letheby) 
 
 Eel (Konig) 
 
 Eggs 
 
 Fish, salmon (Konig) .... 
 
 Fish, sole (Konig) 
 
 Fish, herrings fresh (Konig) . 
 
 Flour, wheaten fine 
 
 Flour, wheaten average .... 
 
 Goose (Konig) 
 
 Horse-flesh (Konig) 
 
 Lentils 
 
 Macaroni (Konig) 
 
 Maize (Pozziali) 
 
 Margarine 
 
 Milk, average cows 
 
 Milk, Devon preserved (Blyth) . 
 
 Milk, average town 
 
 Milk, condensed English (Bell) . 
 Milk, condensed Swiss, sweetened . 
 Milk, condensed Swiss, unsweetened 
 
 Mutton, ordinary 
 
 Oatmeal 
 
 Parsnips (Parkes) 
 
 Pork (Konig) '.'.....'. 
 Potatoes ...".... 
 
 Rice 
 
 Turnips (Konig) 
 
 Veal, lean (Konig) 
 
 
 In 
 
 100 parts 
 
 
 
 Water. 
 
 Proteins. 
 
 Fats. 
 
 Carbo- 
 hydrates. 
 
 Salts. 
 
 15*40 
 
 o-8o 
 
 . 
 
 83*5 
 
 0*30 
 
 I5-00 
 
 9-00 
 
 73-00 
 
 — 
 
 3'0O 
 
 II-30 
 
 12*70 
 
 2*00 
 
 7l*0O 
 
 3*oo 
 
 I470 
 
 7*40 
 
 I'lO 
 
 75*80 
 
 1 -co 
 
 72-00 
 
 2 1 *oo 
 
 6 # oo 
 
 — 
 
 I'OO 
 
 75*00 
 
 15-00 
 
 8-40 
 
 — 
 
 i*6o 
 
 49'IO 
 
 29-60 
 
 0'20 
 
 — 
 
 2l*IO 
 
 52-20 
 
 23-30 
 
 1 4 '00 
 
 — 
 
 4-00 
 
 87*00 
 
 1-50 
 
 — 
 
 10*50 
 
 I'OO 
 
 8-oo 
 
 15-60 
 
 I -30 
 
 73*40 
 
 1*70 
 
 39'5o 
 
 8-oo 
 
 I'OO 
 
 50*00 
 
 1*50 
 
 40-00 
 
 8-oo 
 
 1 '50 
 
 49 "20 
 
 1*30 
 
 12*00 
 
 2 00 
 
 85-00 
 
 — 
 
 roo 
 
 8-oo 
 
 1 -00 
 
 90-00 
 
 — 
 
 I'OO 
 
 17*00 
 
 — 
 
 80 "OO 
 
 — 
 
 3-00 
 
 17-00 
 
 I'OO 
 
 74-00 
 
 — 
 
 8-oo 
 
 89-00 
 
 2 'OO 
 
 2 - 00 
 
 5*50 
 
 1*50 
 
 85-50 
 
 5'00 
 
 0-50 
 
 7-80 
 
 1*20 
 
 87-80 
 
 I -co 
 
 0'2O 
 
 IO'OO 
 
 I'OO 
 
 41-00 
 
 28-00 
 
 23'00 
 
 TOO 
 
 7-00 
 
 36-00 
 
 31-00 
 
 28-50 
 
 — 
 
 4'5o 
 
 48-00 
 
 32-00 
 
 9'00 
 
 7-00 
 
 4*00 
 
 66'oo 
 
 2-70 
 
 26-70 
 
 2-80 
 
 i*8o 
 
 57*5° 
 
 12-50 
 
 28'50 
 
 — 
 
 1-50 
 
 73"5o 
 
 13*50 
 
 n-6o 
 
 — 
 
 1*40 
 
 76-00 
 
 15-00 
 
 7-00 
 
 — 
 
 2*00 
 
 86 -oo 
 
 12-00 
 
 0-50 
 
 — 
 
 1*50 
 
 80-00 
 
 IO'OO 
 
 8-oo 
 
 — 
 
 2 - 00 
 
 16-50 
 
 13-00 
 
 1-50 
 
 68-30 
 
 0-70 
 
 15-00 
 
 1 1 00 
 
 2*00 
 
 71*20 
 
 o*8o 
 
 38-00 
 
 1 6 "oo 
 
 45*50 
 
 — 
 
 0-50 
 
 74*30 
 
 21-70 
 
 2 - 6o 
 
 — 
 
 I'OO 
 
 12-50 
 
 24-80 
 
 i-8o 
 
 58*40 
 
 2-50 
 
 13-10 
 
 9 '00 
 
 0-30 
 
 76-80 
 
 o*8o 
 
 i3*5o 
 
 IO'OO 
 
 6-70 
 
 64*50 
 
 1*40 
 
 1203 
 
 07$ 
 
 82-00 
 
 — 
 
 5*22 
 
 86-90 
 
 4-70 
 
 3'50 
 
 4*20 
 
 0*70 
 
 9o-35 
 
 4-20 
 
 i*i5 
 
 350 
 
 070 
 
 86-oo 
 
 5-00 
 
 4*oo 
 
 4'30 
 
 0*70 
 
 27-00 
 
 12-00 
 
 840 
 
 50-80 
 
 2*00 
 
 25-60 
 
 I2-30 
 
 I I'OO 
 
 48-70 
 
 2-40 
 
 61-85 
 
 ii*35 
 
 11*25 
 
 13*35 
 
 2*00 
 
 76-00 
 
 1 8 00 
 
 5-00 
 
 — 
 
 I'OO 
 
 15-00 
 
 13-00 
 
 6*oo 
 
 6300 
 
 3*oo 
 
 82-50 
 
 1*30 
 
 070 
 
 14*50 
 
 I'OO 
 
 15-60 
 
 22'00 
 
 2'00 
 
 58*00 
 
 2*40 
 
 47'5o 
 
 1 6 "OO 
 
 34*oo 
 
 — 
 
 2-50 
 
 74-00 
 
 2'00 
 
 0*20 
 
 21*84 
 
 roo 
 
 IO'OO 
 
 5*oo 
 
 O'lO 
 
 84-40 
 
 050 
 
 91-00 
 
 1 -oo 
 
 0*20 
 
 6-So 
 
 I'OO 
 
 78-00 
 
 19-00 
 
 I*50 
 
 
 1-50 
 
140 FOOD. 
 
 With a table of this kind, it is quite easy to calculate the 
 amount of protein, fat, carbohydrates, water, and salts in any 
 given weight of a food stuff and from these data its Calorie value. 
 However, the mere expression of potential energy cannot fix 
 dietetic value; in order that the energy shall be obtained, the 
 food must not only be digested and taken into the body 
 properly prepared, but its energy must be developed at the place 
 and in the manner proper for nutrition. For these reasons it is 
 difficult to compare rightly the potential energy available by the 
 burning of a food stuff outside the body with that which is 
 obtained as the result of combustion within the body, and in 
 attempting to estimate the nutritive values therefrom, allowance 
 must be made for the different degrees of digestibility, the effects 
 of cooking, or preservation with consequent destruction of 
 vitamines, and even the actual bulk taken. In the case of fats, 
 their nutritive value seems to depend largely on their digestibility, 
 while of the carbohydrates there is little reason to think that 
 starch, grape sugar, or cane sugar differ much in their nuitritive 
 value, though experiments indicate that cane sugar is more 
 fattening than starch. Among the proteins, we know that gelatin 
 and chondrin have a lower nutritive value than the ordinary 
 proteins, and that vegetable proteins are as nourishing as the 
 animal. 
 
 With regard to mechanical or useful labour and the amount of 
 energy required to be supplied by food to produce that external 
 work it is estimated that, under ordinary circumstances, a man 
 transforms one-sixth of the total available energy of his food into 
 work, the rest being lost in the form of heat. This loss is inevit- 
 able, but it compares favourably with that experienced in a steam 
 engine, where the work done is about one-eighth of the potential 
 energy of the fuel consumed. As the average external work of 
 an ordinary man at rest is calculated to be equivalent to some 
 410 Calories, the total heat value of his food should not be less 
 than six times this or say 2500 Calories. On this basis the 
 following may be accepted as standards of the number of Calories 
 which must be supplied for work of different degrees of severity: — 
 
 Calories. 
 
 1. Rest (clerk working in an office) 2500 
 
 2. Professional work (lawyer or doctor) .... 2650 
 
 3. Moderate muscular work .,...., 3100 
 
 4. Severe muscular work 3600 
 
 5. Hard work (navvy) 5000 
 
 Diets. — So far, we have discussed the nature, uses, and nutri- 
 tive values of the food stuffs individually ; it is necessary now to 
 briefly discuss them collectively in reference to their powers of 
 maintaining life — whether any one of them alone is capable 
 
DIETARIES. 
 
 141 
 
 of supporting vitality, or what combinations and what quantity of 
 them experience and experiment teach us are useful in the food 
 of man. There is abundant evidence to prove that no one 
 group of alimentary substances is alone sufficient to sustain life 
 for any length of time, but that a mixed diet is necessary. Such 
 evidence is derived from instinctive proclivities, from considera- 
 tions of the comparative anatomy of our digestive organs, from 
 experience and experiment. That man cannot live on any one 
 group of the food stuffs is shown by an examination of the needs 
 of the body, as demonstrated by the daily loss by the kidneys, 
 bowels, skin, and lungs. 
 
 Experience teaches us that our requirements as to food vary 
 much with our exposure to different conditions, and that accord- 
 ing to the expenditure of our bodies so should the materials be 
 supplied which are best calculated to yield what is wanted. The 
 human body has been compared to a machine, but it differs 
 therefrom in this, that wear is constantly going on independently 
 of any useful work done, which is not the case in a mechanical 
 engine. Determinations as to the quantity of food daily required 
 by the body have been obtained by means of extended observa- 
 tions of the diets of classes and communities, and also by esti- 
 mating the sum of excreted matters, which, of course, must be 
 compensated by a suitable supply of food. 
 
 The following table (modified from Atwater) gives the com- 
 position of the ordinary diet actually consumed by individuals of 
 diverse nationality and different social rank : — 
 
 
 
 Nutritive constituents. 
 
 
 Classes. 
 
 Protein. 
 
 Fat. 
 
 Carbo- 
 hydrate. 
 
 Total. 
 
 energy. 
 
 Sewing girl (London) 
 Factory girl (Leipzig) 
 Labourer (Lombardy) . 
 Student (Japan) . 
 Lawyer (Munich) 
 Master tailor (England) 
 Blacksmith (England) . 
 Workman (Russian) . 
 Glass-blower (American) 
 Artisan (Canada) 
 Brickmaker (American) 
 Weaver (Lancashire) 
 
 
 Grammes. 
 
 53 
 
 52 
 82 
 
 97 
 131 
 
 131 
 
 176 
 
 132 
 
 95 
 109 
 
 222 
 
 114 
 
 Grammes. 
 
 33 
 
 53 
 
 40 
 
 16 
 
 95 
 
 39 
 
 7i 
 
 80 
 132 
 109 
 260 
 150 
 
 Grammes. 
 316 
 301 
 362 
 438 
 327 
 
 525 
 667 
 
 583 
 481 
 
 527 
 758 
 522 
 
 Grammes. 
 402 
 406 
 484 
 551 
 
 553 
 695 
 914 
 
 795 
 708 
 
 749 
 
 1243 
 
 786 
 
 Calories. 
 l820 
 I94O 
 2192 
 
 2343 
 270O 
 
 3053 
 4117 
 
 3675 
 3590 
 3622 
 
 6460 
 
 4OOO 
 
 Interesting as these figures are, care needs to be taken that 
 
 v 
 
142 FOOD. 
 
 their limited range of usefulness is not forgotten. They indicate 
 the needs of typical individuals living under known conditions, 
 but they cannot be applied rigidly in any or every particular case. 
 The facts show strikingly the relation between the muscular 
 activity of the individual and the caloric value of his diet and, on 
 that account, are exactly what is to be expected from the theory 
 of the conservation of energy. The most obvious lesson to be 
 learnt from these actual dietaries appears to be that (i) people 
 doing active muscular work, such as blacksmiths and athletes, 
 when free to choose their diet, select a dietary having a total 
 fuel value of some 4400 Calories ; (2) people doing ordinary 
 muscular work, such as carpenters, farmers and labourers, choose 
 a diet representing some 3300 Calories ; (3) people doing light 
 muscular work, such as professional men and clerks, select a 
 dietary representing about 2500 Calories. 
 
 We may now inquire what light physiological experiment 
 throws on this subject, more particularly what proportion of the 
 whole diet, protein, fat and carbo-hydrate, should each contribute. 
 The metabolic output of an individual varies naturally with his 
 size, age and work, but it may be said that an ordinary man, 
 weighing 70 kilos or 11 stones, excretes 20 grammes of nitrogen 
 and 300 grammes of carbon daily. 
 
 Assuming protein to contain 16 per cent, of nitrogen, it is 
 clear that an input of 125 grammes of protein will supply the 
 requisite amount of nitrogen, but we cannot accept this as the 
 absolute answer to the question as to how much protein such a 
 man must consume daily, owing to the fact that the body can 
 establish nitrogen equilibrium on various quantities of protein. 
 In a typical man, 20 grammes input of nitrogen means 20 grammes 
 output, so also 15 grammes input is followed by 15 grammes 
 output, and so on, the nitrogen excretion keeping pace with the 
 nitrogen intake. The question arises, how much is the best ? 
 The answer is not easy, because we do not know how much 
 protein or nitrogen is actually needed to keep the tissues in 
 repair. A starving man will eliminate 4 grammes of nitrogen 
 daily, and, practically, nitrogenous equilibrium cannot be estab- 
 lished on less than an intake of 12 grammes. Can we accept 
 this as the minimum ? The view held, hitherto, by physiologists 
 is that we cannot, because, when the protein is reduced to a 
 minimum, there is a risk of having " threadbare tissues " and a 
 consequent lack of disease-resisting power on the part of the 
 body ; moreover, to do so is to ignore the fact that the function 
 of protein is to supply energy as well as merely repair tissues, and 
 that it is unsafe to rely only on the fats and carbohydrates as 
 sources of heat and energy. On this principle it has been held 
 
DIETARIES. 143 
 
 that the proper nitrogen standard for the ordinary man of 70 
 kilos weight is 118 grammes of protein daily. This represents 
 105 grammes of absorbable protein or 16 grammes of nitrogen 
 and equivalent to 1*5 grammes of protein per kilogramme of 
 body weight. 
 
 Recent work on metabolism has seriously challenged this 
 view. On the one hand, theoretical reasoning from the fact that 
 an excess of nitrogen is so rapidly eliminated from the body and, 
 on the other, practical experiment suggest that protein in this 
 large amount is not necessary in health to supply the needs of the 
 body, but rather increases the work of nitrogenous excretion with 
 no apparent advantage. Chittenden, as the result of a long series 
 of experimental observations, has been the main exponent of 
 this view. He argues that o"i gramme of protein capable of 
 metabolism per kilogramme of body weight represents the 
 minimum protein requirement daily, but, as it would probably be 
 advisable to allow a margin of safety, he suggests that a daily 
 input of from 50 to 60 grammes of protein is sufficient for a man 
 of from 60 to 70 kilogrammes weight. This is virtually a reduction 
 of fifty per cent, on the generally accepted standard. 
 
 It may be asked what practical conclusion is to be drawn from 
 these divergent views? It is probable that the orthodox standard 
 of 118 to 125 grammes of protein daily may err on the side of 
 excess for the ordinary man doing no specially hard work ; 
 equally, the newer idea of reducing the amount to half may be 
 open to risk if accepted as a standard for the general population. 
 From the available evidence, we do not think it has been proved 
 that a diet containing protein in a much smaller proportion than 
 that of 100 grammes a day for an adult of 70 kilogrammes, 
 is permanently beneficial either to the individual or to the race, 
 and especially for those whose occupations require considerable 
 muscular exertion. 
 
 We may now pass on to inquire how much fat and carbo- 
 hydrate are required in a daily diet. These two alimentary 
 groups are the main source of the carbon supplied to and needed 
 by the body and also of the energy. For a man of 70 kilo- 
 grammes in body weight, doing ordinary work, some 300 grammes 
 of carbon are needed daily to meet the daily loss under this 
 head. If we assume that a man takes in 100 grammes of 
 protein of which only two-thirds is fully metabolized, we get 36 
 grammes of carbon available from this source, leaving 264 
 grammes to be supplied by fats or carbo-hydrate. So far as a 
 mere source of energy is concerned, the body cells are indifferent 
 whether it be fat or carbo-hydrate, but we must remember that it 
 takes 2\ parts of the latter to supply as many Calories as one of 
 
144 FOOD. 
 
 the former. On the other hand, fat is more slowly metabolized 
 than carbo-hydrate, is more expensive, and usually less digestible. 
 Experience indicates that for economic and digestive reasons, 
 about one-fifth of the balance of carbon should come from fat, in 
 other words, some 60 grammes of fat are desirable, yielding 46 
 grammes of carbon, the remaining 218 grammes of carbon being 
 obtained from an input of 540 grammes of carbo-hydrate. A 
 dietary prepared on these lines would have a fuel value of 3182 
 calories; possibly the fat might need to be reduced, say, to 50 
 grammes, in which case, unless it were replaced by carbo-hydrate, 
 the fuel value of the dietary would not be more than 3089 
 Calories. What should be the exact proportion of fat to carbo- 
 hydrate is difficult to say; in our opinion, the ratio in a well- 
 designed dietary should be 1 part of fat to 7 or 8 of carbo- 
 hydrate, but it is impossible to lay down any hard and fast rule ; 
 opportunity, digestion and pecuniary circumstances are the 
 determining factors. 
 
 The general principles of diet may be summed up thus : (1) 
 No single nutritive principle, whether nitrogenous or non-nitro- 
 genous, can support life except for a very short time. (2) Life 
 may be supported upon one nitrogenous and one non-nitrogenous 
 principle for a long time, but for a permanency salts would require 
 to be added. Thus proteins and fats, or proteins and starches, 
 would support life. (3) For the best forms of diet, both fats and 
 carbo-hydrates are needed in addition to nitrogenous matter, and 
 in all probability both starch and sugar among them. It would 
 also appear that a due admixture of more than one form of 
 nitrogenous principle is advisable. 
 
 Various conditions of life influence the amount of food 
 required; the more important of these are work, rest, weight, 
 age, sex, and climate. No one disputes the view that with an 
 increase of musculo,?' work there must be a corresponding increase 
 in the total amount of food consumed ; the problem is, should 
 it be met by an increase of protein, of fat, or of carbo-hydrate 
 or should all be increased? As modern research indicates that 
 muscular work makes no special demand on one nutritive con- 
 stituent more than another, it is logical to assume that all must 
 be increased. The standard amounts of the different nutritive 
 constituents required daily, when doing ordinary and hard work, 
 may be stated thus : — 
 
CALCULATION OF DIETS. 
 
 145 
 
 Kind of work. 
 
 Protein. 
 
 Fat. 
 
 Carbo- 
 hydrate. 
 
 Potential 
 energy. 
 
 Ordinary work . 
 Haid work .... 
 
 Grammes. 
 IOO 
 l6l 
 
 Grammes. 
 60 
 98 
 
 Grammes. 
 
 540 
 
 520 
 
 Calories. 
 3182 
 3706 
 
 These amounts are, of course, theoretical standards, and, as 
 such, only approximate. The need of so great an Increase in the 
 proteins during hard work is doubtful, while, on the other hand, 
 the need of carbon under the same conditions is possibly greater 
 than given in the above table. As already stated, all the ingre- 
 dients are reckoned as being quite free from water, but would in 
 actual practice be combined with quite their own weight of water, 
 making the total weight of solid food taken to be from 40 to 20 
 ounces. In addition, too, some 40 to 60 fluid ounces of water 
 would be taken as drink. As a general rule, it may be accepted 
 that a man consumes daily about j^o °f n ^ s own weight of dry 
 food, and some yoo" of water, or, in other words, each pound of 
 his body weight receives in twenty-four hours 0*15 oz. dry food 
 and o # 5 oz. of water. 
 
 It will be readily understood that, though the above-named 
 amounts are accepted as standards, in actual life there are very 
 great individual differences in diets, and that no single standard 
 will meet all cases, because no two men eat exactly the same. 
 The chief influences which affect the amount of food and drink 
 taken are sex, age, work, and climate. 
 
 As regards sex, women are said to require 10 per cent, less 
 than men ; while in reference to age, during young life nitrogenous 
 and fatty food are particularly needful to provide for the growth 
 of tissues ; in old age, proportionate reductions are demanded, as 
 there is not only lessened labour but actually lessened body 
 metabolism or tissue change. If people are doing great work, 
 there is a natural need of more food, especially for proteins and 
 fats ; also in a less degree for water. The influence of climate on 
 diet is not very defined. In cold countries more fat is consumed 
 than in hot, but how far this increase is due to greater need for 
 energy and body warmth or increased exertion is not quite clear. 
 
 It is the great diversity which exists as regards the food 
 consumed by the human race in all parts of the world that is the 
 most remarkable feature in the study of dietaries. Some people 
 live upon a wholly vegetable, others on a wholly animal, and 
 ethers on a mixed diet. It has already been explained how un- 
 suited any single vegetable food, such as bread, or any single 
 
I46 FOOD. 
 
 animal food, such as meat, is to supply the daily requirements of 
 the body, and how a judicious mingling of the various food stuffs 
 affords the greatest nourishment in the least bulk. The mixed 
 diet may be regarded as that which in Nature's plan is designed 
 for man's sustenance. On this he appears to attain the highest 
 intellectual and physical vigour, and it is this diet which he 
 consumes by general inclination when circumstances allow the 
 inclination to guide him ; also it is in conformity with the construc- 
 tion of his teeth and the arrangements of his digestive apparatus 
 in general, ftowever, where custom and habit have given certain 
 races a peculiar suitability for a purely vegetable diet, the argu- 
 ments in favour of a mixed diet are not sufficiently strong for the 
 reversal of the customs of many ages. 
 
 For translating or changing the elements of a diet into terms 
 of food articles, or vice versa, it is important to remember that no 
 mere calculation of the amounts of food stuffs can properly 
 measure the efficiency of any particular diet, but that other con- 
 ditions must be considered ; the chief of these will be relative to 
 hours and arrangements of meals, digestibility of food, and the 
 effects of cooking. 
 
 Hours of Eating. — Next to the quantity and quality of food, 
 attention must be given to the method of taking it. Food should 
 be taken with regularity and at proper periods ; long intervals 
 between meals are specially hurtful. As a rule, it may be said 
 that the hours of eating meals are the result of custom and of the 
 other trivial conditions peculiar to different classes of society. 
 The prevailing custom is for these meals to be taken during the 
 day at intervals of about five or six hours. Observation has shown 
 that an ordinary meal is digested and has passed on from the 
 stomach in about four hours' time, and thus, according to the above 
 custom, the stomach is allowed to remain for a short period in a 
 state of rest before it is filled with food again. Whether the 
 largest meal of the day, dinner, should be taken at midday or at 
 sundown is a question mainly to be decided by circumstances. 
 The former hour is found to be more convenient to men doing 
 manual labour, while the latter seems to be best adapted to the 
 wants of the busy man in the upper and middle classes. Pro- 
 vided the evening meal is not taken at too late an hour, and not 
 too large, there is no reason against this arrangement ; but it 
 must not be forgotten that the habit of going to bed or to sleep 
 on a full stomach after a meal is particularly injurious. Similarly, 
 a hearty meal should neither follow nor precede violent exertion. 
 In each case, the stomach is unfit for the vigorous discharge of 
 its office. All persons, both rich and poor, should endeavour to 
 take a little food with either a cup of hot tea or coffee in the 
 
COOKING OF FOOD. 147 
 
 early morning before going out to woik. Such a practice 
 strengthens the body and digestion at a time when its powers are 
 at their lowest, and, too, in malarial countries has a marked 
 influence in keeping off fever. 
 
 Digestibility of Food. — Far more important, as an index of 
 its nutritive value, than mere calculations as to how much protein, 
 fat, etc., a given article of food contains, is the determination of 
 the degree of its digestibility. On this point it may be said that 
 the proteins and fat derived from the animal world are more readily 
 digested than those obtained from vegetables. As to the carbo- 
 hydrates, no general rule can be laid down beyond that white 
 bread and rice are the most digestible. These statements must, 
 however, be regarded only as giving broad differences of 
 digestibility between foods, and in particular cases may be 
 considerably modified, especially if allowance be made for the 
 effects of cooking. 
 
 Cooking. — By cooking, our food is rendered more pleasing to 
 the eye, agreeable to the palate, and digestible by the stomach. 
 Apart from its power of removing any obnoxious property in a 
 food by killing any parasites or disease germs existing in it, cook- 
 ing so alters the texture of a food as to render it more easy of 
 mastication and subsequent reduction to a fluid state by the 
 stomach. Thus a piece of meat before cooking is tough and 
 stringy, but when cooked the muscular fibres are given a firmness 
 from the coagulation of their albumin, and the connective 
 tissue which binds the muscle-fibres together is made into a 
 soft and jelly-like mass. The result of all this is, the meat 
 is rendered less coherent and mo-re digestible, and capable 
 of being broken down by the teeth and the digestive juices. 
 In the same way, cooking makes vegetables and grains softer, 
 loosens their structure, and enables the digestive juices to 
 penetrate into their substance. It also aids digestion by its 
 action of breaking up the starch granules, which exist so largely 
 in vegetables and grains ; if not so broken up, starch offers 
 considerable resistance to digestive action. The warmth imparted 
 to food further aids digestion, and exerts a reviving effect 
 on the system. 
 
 We may say that there are six common methods of cooking ; 
 namely, boiling, stewing, roasting, broiling or grilling, baking, and 
 frying. 
 
 Boiling. — This may have for its object either the extraction 
 from the food of its nutritive principles or their retention in it. 
 If we wish to extract all the goodness of meat into some surround- 
 ing liquid such as water, as when we make a soup or a broth, the 
 article should be finely cut up and placed in cold water. After it 
 
148 FOOD. 
 
 has soaked for some while, heat should be applied slowly ; if a 
 broth is to be made, the heat, though constantly applied, is not 
 allowed to reach actual boiling for some time, by which procedure 
 much of the albumin of the meat is extracted before the sub- 
 sequent greater heat has been able to coagulate it, and, all the 
 natural juices having for the most part flowed out, the meat itself 
 is left in a nearly tasteless state, but not without some nutritive 
 value. In the making of a soup the same procedure is adopted, 
 with this difference, however, that the boiling is kept up somewhat 
 longer, whereby more of the gelatin of the meat is extracted, and 
 the actual meat itself, owing to more complete deprivation of its 
 constituent juices, rendered still more tasteless and less nutritious. 
 Thus treated, the meat yields its essential principles to the sur- 
 rounding liquid, which gains in flavour and nutritive properties, 
 the essential difference between the broth and the soup being 
 merely one of degree — that is, how much of the goodness of the 
 meat passes out of it into the surrounding liquid. In the making 
 of a broth some of the meat juices, gelatin, and other constituents 
 still remain in the meat, because the albumin is permitted to 
 coagulate before they have all escaped ; while in the other case 
 practically nothing remains of the meat but fibrous tissue, all the 
 rest having passed out into the soup. A due appreciation of the 
 difference between a broth and a soup is important, especially 
 the fact that after the making of a broth the meat residue has still 
 considerable nutritive value, whereas after the preparation of a 
 soup the meat residue has none. 
 
 If, on the other hand, the object of boiling is not to extract 
 the constituents out of meat, but rather to retain in it all its 
 flavour and nutriment, then it should not be cut up, but left as a 
 large piece, plunged suddenly into hot or nearly boiling water, 
 and quickly brought to the boil. The application of sudden heat 
 in this manner coagulates the albuminous matter on the surface 
 of the meat, closes its pores, makes an impermeable external coat 
 which stops the escape of the juices from the inner and deeper 
 parts. It is on this principle that a boiled leg of mutton is 
 cooked, taking care, in order to complete the cooking, that the 
 boiling is neither too vigorous nor too long continued, but, after 
 the first short period of boil, the water is only just allowed to 
 simmer — that is, be barely at the actual boil. If cooked carefully 
 in this way, the central part of such a joint remains juicy and 
 tender. The most usual fault of cooking meat in this manner is 
 allowing the water in which it is boiled to remain at too high a 
 temperature after the first dipping in to coagulate the surface. 
 The actual period of boiling need not and should not last longer 
 than a few minutes; after that the temperature required for the 
 
COOKING OF FOOD. 1 49 
 
 • 
 
 surrounding water is not greater than 160 F., actual boiling being 
 212 . It is usual to add salt to the water in boiling a joint such 
 as has been just explained. There are certain reasons for so 
 doing : first, it has a direct coagulating effect upon the surface 
 albumin; second, it slightly raises the boiling-point of water; and 
 third, it increases the density of the water, the effect of which is 
 to render less active the oozing out of the meat juices. 
 
 The same principles should guide us in boiling a fish, but 
 with this reservation — namely, that fish being relatively fragile as 
 compared with red meat, many kinds would break if suddenly 
 dipped into boiling water. To avoid this, water just below the 
 boiling-point must be used, and the whole process of cooking the 
 fish be completed without actually boiling the water at all. The 
 breaking of a fish by the agitation of boiling water not only spoils 
 the look of the fish, but also opens up the flesh, producing outlets 
 for the escape of its juices, and thereby losing some of its nutritive 
 elements, besides spoiling its flavour. One of the most prevalent 
 errors amongst unscientific cooks is the idea that by boiling is 
 meant vigorous bubbling of the water : more good is done, and 
 just as much heat obtained, by a very gentle simmer of the water 
 as there is when the saucepan lid is constantly being lifted. The 
 cooking-point of meat is a temperature of 160 F., while the 
 boiling-point of water is 212 F. The same principle of trying 
 to retain the soluble and diffusible constituents of a food is 
 involved when potatoes are boiled in their skins ; but in the case 
 of a vegetable like the potato, we retain its constituents within it, 
 not by coagulating any surface albumin, because there is none, 
 but by boiling them in their skins or jackets. Over 50 per cent. 
 of the saline constituents of the potato is potash, and potash is 
 an important constituent of blood, hence the great importance of 
 not allowing any waste of the potash from the potato by allowing 
 it to be largely dissolved out of it during the act of cooking by 
 boiling after peeling. It will readily be seen that this loss of 
 potatoes does not occur when potatoes are cooked in such a manner 
 as to be eaten with their own juice (broth) as in Irish stew, in 
 which case their previous peeling does no harm. Steamed 
 potatoes possibly lose less potash juice than when boiled. Speak- 
 ing generally, boiled food is less tasty, but more digestible than 
 when cooked in any other way. 
 
 It will be convenient here to discuss another cooking method, 
 namely, stewing, because it is commonly regarded as a mere 
 modification of boiling ; this is only partially true, because they 
 are essentially opposite processes. If the reader has understood 
 what has been written above upon the boiling of a leg of mutton, 
 he will see that its object is to so raise the temperature of the 
 
ISO FOOD. 
 
 meat, using water as the medium by which the heat is conveyed 
 to the meat, that it shall as nearly as possible retain all its 
 juices. Now, in stewing, this is largely reversed, because the water 
 is used not only as a heat-giver, but also as a solvent for extract- 
 ing from the meat more or less of its juices. Much of this 
 extraction of meat juice in stewing is more accurately expressed 
 as an act of diffusion rather than of solution, capable of being 
 best secured at high temperatures than low ; but experiment 
 teaches us that albumin, which so largely constitutes the diffusible 
 juice of meat, coagulates and gets hard and tough if long exposed 
 to a heat anything near the boiling-point of water ; hence the 
 need, if stewing is to be properly done, and the meat not rendered 
 so tough, curled, and hard as to be more or less uneatable, that the 
 process of stewing should be performed at a temperature of 160 
 F. or so. This can be readily done if a daw-marie, or water bath, 
 be used. The ordinary carpenter's glue-pot is a familiar form of 
 water bath, being simply a vessel immersed in an outer vessel of 
 water. The water in the outer vessel may boil, but that in the 
 inner one never does, because evaporation from its surface keeps 
 its temperature lower than that of the water from which it gets its 
 heat. All well-equipped kitchens have these double vessels, and 
 every ironmonger sells them ; but in the absence of such a double 
 saucepan, every housewife can readily improvise one by perform- 
 ing the stewing in an earthenware jai or glass placed within an 
 ordinary saucepan containing water. It is the more general appre- 
 ciation of the value and use of the water-bath mode of stewing 
 by French men and women that makes their average cooking 
 so much higher than that of the average English man or woman. 
 English people are apt to speak with contempt of the stewed beef 
 of the Frenchman, forgetting the fact that he never eats it alone, 
 but always associated with a soup or potage, which really contains 
 the juices of the beef; and the two dishes combined constitute 
 identical and quite as nutritious articles of diet as the British joint. 
 
 Hashing is the same process as stewing, only that the meat has 
 been previously cooked instead of being fresh. 
 
 Before dismissing this subject of stewing, a few remarks upon 
 the making of ordinary beef-tea or beef extracts as sold under the 
 names of " extract of meat " and " Bovril " may not be inappro- 
 priate, particularly as they afford some points of difference from 
 the juices of an ordinary stew. Beef-tea is made by chopping up 
 lean meat very finely and then macerating it in cold water, and 
 the broth thus obtained heated in order to alter its raw flavour. 
 During this heating, which should not exceed 160 F., or just 
 sufficient to coagulate the albumin and colouring matter, a sort 
 of scum rises to the surface ; much of this is fat, and is rightly 
 
COOKING OF FOOD. I 5 I 
 
 removed, but if the heating is carried too high, some of the other 
 nutritious elements coagulate on the surface, and get removed 
 instead of being left behind. If well prepared, beef-tea is a 
 highly nutritive and restorative liquid, with an agreeable, rich, 
 meaty flavour. If badly prepared, by being subjected to pro- 
 longed boiling, beef-tea is merely a solution of the non-coagulable 
 saline constituents of meat — namely, bodies known as kreatin, 
 kreatinin, lactic acid, and phosphates. These are all most 
 excellent, but to be regarded as stimulants rather than as nutrients. 
 This explains why in some states of prostration, during illness, 
 when the blood is insufficiently supplied with these flesh juices, 
 the administration of beef-tea, beef extracts, and such-like pre- 
 parations does much good ; but the danger lies in their being 
 regarded as foods suitable for the normal sustenance of the body. 
 This they are not, and, from the very nature of their composition, 
 wanting largely of the nutritious constituents of meat, they never 
 can be. 
 
 Roasting. — Just as stewing may be regarded as the national 
 method of cooking on the Continent, so may roasting be regarded 
 as our national method of flesh cooking. Roast meat is usually 
 thought to be more savoury but less digestible than when either 
 boiled or stewed, while, too, the loss is greater, but the same 
 principle underlies it, namely, the retention of the nutritive juices 
 by the formation of a coagulated layer on the surface. In roasting 
 the juices of the meat are retained (with the exception of 
 those which escape as gravy on the dish), while in stewing, they 
 go more or less completely into the water. In stewing, the heat 
 is communicated to the meat by convection or actual contact; 
 in roasting, the heat is nearly all dry heat radiated to the surface 
 of the joint from the fire. The high temperature rapidly given 
 by radiation to the meat surface forms a thin crust of hardened 
 and half-carbonized albumin ; this prevents the evaporation of 
 the meat moisture, sets up a certain amount of pressure inside 
 the joint resulting in the gradual loosening of the fibres and 
 raising of the deeper parts of the flesh to the cooking temperature 
 of about 160 F. In all roasting processes, to hasten its course 
 and prevent burning of the superficial parts, the joint is basted or 
 kept constantly enveloped in a varnish of hot melted fat, which, 
 while assisting in the communication of heat, checks the undue 
 evaporation of the juices, or, in other words, during roasting heat 
 convection is established by the medium of a fat bath, while in 
 stewing or boiling it is supplied by a water bath. This mode 
 of cooking in a fat bath is applicable not only to ordinary joints 
 but to fish, which, in the form of fillets of plaice or skate, 
 supplemented by roasting in bacon fat and garnished with some 
 
152 FOOD. 
 
 previously well-boiled haricots, constitute both a savoury, cheap, 
 and nutritious meal for any poor man. 
 
 Broiling or grilling is the same in principle as roasting, but 
 the scorching of the surface is greater owing to the larger surface 
 exposed to heat. Baking is analogous, except that the operation 
 is carried on in a confined space, such as an oven. Owing to 
 the confined space and want of ventilation in the chamber or 
 oven in which baking is carried on, the condensed vapour from 
 the article being cooked and the fatty acids, if it be meat, are 
 prevented from escaping, rendering the food so cooked richer 
 and stronger for the stomach. For these reasons, baked food is 
 unsuitable for the sick and delicate. 
 
 Frying^ speaking generally, is a bad way of cooking, as owing 
 to the heat being applied through the medium of fat, the article 
 so cooked is penetrated with oily matter and often indigestible. 
 In frying, the heat is applied usually much above that of boiling 
 water, as the medium fat can be heated much above 21 2° F. before 
 it boils ; and it is probably largely the difference of temperature 
 to which fish is subjected in the two processes that causes the 
 difference between a boiled sole or mackerel and a fried one. 
 Over and above this, their difference may be due to the fact that 
 the flavouring juices are retained in the flesh of the fried fish, 
 while more or less of them escape into the water when boiled. 
 
 It is needless, perhaps, to say that all things used in cooking 
 should be scrupulously clean and carefully cleansed with boiling 
 water after each time of use. 
 
 Diseases attributable to Faulty Dieting. — That evils may arise 
 from the indigestibility and bad cooking of food has already been 
 alluded to. There remain for consideration certain bad effects 
 which may arise from either defects as to quantity or quality. 
 The alterations in quantity of food may be either in the direction 
 of excess or deficiency. An excess of food, due to too large or too 
 frequent meals, usually leads to an accumulation in the bowels 
 resulting in dyspepsia, constipation, or even irritative diarrhoea. 
 The excess of food may in some cases be absorbed, but more 
 usually large quantities pass away by the bowel absolutely undi- 
 gested. . Any excessive consumption of proteins, especially if 
 unaccompanied by a proportionate increase of exercise, usually 
 results in enlargement of the liver with more or less dyspepsia, 
 diarrhoea, or even gout, the urine containing an excess of urea, 
 uric acid, and even albumin. An excessive consumption of 
 proteins, with a proportionate reduction of fats and carbohydrates, 
 was the basis of so-called " Banting ; " it being an attempt to 
 reduce accumulation of fat in the body by virtue of the well- 
 recognized power which proteins have of favouring a rapid dis- 
 
DISEASES ATTRIBUTED TO FAULTY DIETING. 1 53 
 
 integration of tissue. Though physiologically sound, banting is 
 unsuited for indiscriminate use as a means to reduce corpulency. 
 An excess of fats or carbohydrates tends to produce stoutness 
 more or less associated with acidity and flatulency, and if con- 
 tinued long, to degenerative changes in the muscles. Little is 
 known of the effects of any excess of mineral salts. Common 
 salt taken in excess increases the change of protein in the body ; 
 while an excess of potash salts in the food leads to an increased 
 excretion of sodium chloride. An excess of water with the food 
 means more urine passed, and also increased tissue activity. 
 
 Deficiency of food \ if protracted, means, of course, a wasting 
 of the tissues as shown by loss of flesh, poorness of blood, 
 followed by physical and mental weakness, and if the loss reach 
 40 per cent, of the normal weight of the body — death. The 
 more or less complete deprivation of proteins gradually leads to 
 loss of muscular strength, mental debility, fever, and eventually 
 a degree of prostration which may end in loss of life. A defi- 
 ciency of fats, even if carbohydrates be given, invariably leads to 
 a lowered state of health. A deficiency or even complete with- 
 drawal of carbohydrates can be borne a long time if fats be given, 
 but a deprivation or deficiency of both fats and carbohydrates 
 although proteins are supplied, soon leads to illness. A defi- 
 ciency of proteins and fats, especially the latter, is the chief 
 characteristic of the dietaries of communities, notably of armies, 
 public institutions, and the poorer classes in general. Any 
 marked diminution in the amount of water taken as food leads 
 to deficient tissue activity, giving rise to undue retention or 
 storage of water in the body, especially in the muscles, with 
 the establishment of defective heakh and disease-resisting 
 power. 
 
 Associated with defects in the supply of the vitamines in a 
 dietary are a number of diseases often referred to as deficiency 
 diseases. Some, like rickets and dwarfism, occur mainly in the 
 young, while others, such as scurvy, osteomalacia, pellagra and beri- 
 beri may occur in both young and adult persons. In each case 
 the essential cause is a defective dietary involving either a 
 deficiency or an absence of the necessary protecting vitamine 
 from the constituent elements of the diet. Thus, the absence of 
 the water soluble anti-neuritic accessory factor or vitamine from 
 the dietary of people living mainly on de-corticated rice is the 
 cause of beri-beri and the poly-neuritis of the tropics. The reason 
 is that the essential vitamine exists in the inner coat of the rice 
 grain, and if this coat be removed in the preparation or milling of 
 the rice, the consumers of that rice ultimately develop the 
 disease. Badly prepared or an insufficiency of whole milk in the 
 
154 FOOD. 
 
 feeding ot children is the cause among them of scurvy, rickets 
 osteomalacia, and dwarfism, because the necessary fat-soluble and 
 water-soluble vitamines normally present in good whole milk and 
 its preparations are absent from the diet. Scurvy in adults results 
 from a similar sequence of events or absence of the necessary 
 protective vitamines from their food : but in their case it is not so 
 much a deficiency from the milk element in the dietary but rather 
 a defect in the other constituents of their daily food, which is 
 generally found to have consisted mainly of salted or preserved 
 meat, biscuits, and dried or preserved vegetables. These dele- 
 terious effects are not due to putrefactive or bacterial decomposi- 
 tion in the food stuffs, but simply to the destruction or absence of 
 the vitamines in what may be called devitalized food. This 
 devitalization or material departure from the fresh condition may 
 be the result equally of faulty preservation, caused by exposure to 
 undue heat and drying or desiccation, as to prolonged keeping : 
 in other words, the more the constituents of a dietary depart from 
 the fresh condition, and the more prolonged the period over which 
 the consumption of such devitalized food extends, the greater 
 are the probabilities of a development of scorbutic symptoms or 
 signs of other deficiency diseases among the consumers. We 
 need to remember that the absence of a specific factor or factors 
 such as the vitamines from the food produces results very different 
 from those that follow starvation. In the latter : e actual re- 
 quirements and other demands are met from the tissues, and there 
 is economy of effort and material. Some harmony among all 
 the processes is secured. But when an individual's diet is 
 deficient in, say, a vitamine, he may still be dealing with lar r s 
 quantities of total food. The truth is, the necessary vitamine 
 supply is quantitatively not independent of the amount of diet as 
 a whole, nor even of its character. For example, an excess of 
 
 carbohydrate in the food may exa rate the effect of a deficiency 
 
 in the fat soluble vitamine : not from any added toxic effect, but 
 because it reduces the consumption of body fat and therefore the 
 mobilization of the store of vitamine which exists in the fat depots. 
 On the other hand, the stimulus to metabolism or tissue char._ 
 produced by an excess of protein might exert an influence in the 
 opposite sense. Modern knowledge has extended the conception 
 of specific functions in nutrition : functions which are independent 
 of energy supply or mere expressions of so much protein, fat, or 
 
 bohydrate. 
 
 Meat. — Although in different parts of the world, the flesh 
 of various kinds of animals is eaten as meat, that chiefly used is 
 beef from the ox, veal from the calf, mutton from the sheep or 
 g :, and pork from the pig. To these may be added the flesh 
 
MEAT. 155 
 
 of fishes. As an article of diet, meat furnishes proteins, fat, and 
 salts. A general analysis of meat yields roughly in a hundred 
 parts 75 of water, 20 of protein, and 5 of fat. The protein is for 
 the most part myosin, which exists in the muscle fibres. This 
 myosin is, strictly speaking, a globulin, soluble only in saline 
 solutions or dilute acids and alkalies. It is the result of the 
 coagulation of the muscle after death, this coagulation constituting 
 the so-called rigor mortis ; in this state meat is tough, but when 
 the rigor mortis has passed off, the meat becomes tender. The 
 coagulation of the myosin is due to the presence of sarcolactic 
 acid. Besides myosin, meat contains other proteins such as 
 small quantities of alkali and serum albumin, also a globulin from 
 blood. Of the total proteins in ordinary meat some 13 per cent, 
 are made use of in the body, and possibly even more in the best 
 samples. The amount of fat in meat of course varies ; it usually 
 solidifies after death, and in bacon consists chiefly of oleates, in 
 beef of palmitates, in mutton of stea rates — these respective kinds 
 of fats being soft and fusible in the order named. It is from 
 these animal fats that the best margarine is made. In good ox 
 flesh about 33 per cent, is fat, in pigs about 50 per cent., in 
 calves about 16 per cent.; in thin or badly fed animals, the fat 
 may be as low as 1 per cent, of the meat. 
 
 The mineral salts of meat are chielly phosphate of potassium 
 with small quantities of magnesium, calcium, and chloride of 
 sodium. Besides these, meat yields certain nitrogenous crystalline 
 bodies, called commonly extractives. These are derived from the 
 changes in the protein of muscle, and constitute the stimulating 
 principles of beef-tea and broth. The chief extractives of meat 
 are kreatin, kreatinin, xanthin, taurin, sarkin, and urea. In 
 estimating the dietetic value of meat some allowance must always 
 be made for bone, which, as usually sold, equals at least \ 
 of the whole, but this is a much less variable item than the 
 fat. 
 
 Constituting as it does so large a proportion of the food of 
 man, a proper inspection of meat intended for food is of the first 
 importance, especially with a view to the detection of whether it 
 be fresh and free from putrefactive changes, and too, whether 
 it be wholesome and sound, and not derived from a diseased 
 animal. It is rare for any one to have opportunities of examining 
 the live stock intended for meat before slaughter. Should such 
 occur it is important to remember that the signs of a healthy 
 animal are, being well nourished, able to rise without difficulty 
 and to walk without lameness. Its coat should be bright and 
 glossy, and free from scabs, boils, or sores. The eyes of the 
 animal should be bright, with mouth and nostrils moist yet free 
 
156 FOOD. 
 
 from discharge. The breathing should be quiet and easy, and 
 the breath free from odour. 
 
 frispection of Meat. — Good and healthy butcher's meat is firm 
 and elastic to the touch, moist, but not wet ; if well fed, marbled in 
 appearance, from small layers of fat between the muscle fibres. 
 Except in the case of veal and pork, good meat is of a bright red 
 colour. On standing awhile, a red juice oozes out ; this should be 
 faintly acid. There should be a fresh but not unpleasant smell. 
 The fat should be firm and whitish yellow in colour, and free from 
 blood-stains. If putrefaction has occurred, the meat is soft, pale, 
 and usually offensive ; if a knife or skewer be thrust into such meat 
 and rapidly withdrawn, it will smell offensively. The juice, too, is 
 usually alkaline, and fails to redden blue litmus paper. Occasionally 
 horseflesh is offered for sale in place of beef. Owing to the bones 
 of the horse and ox differing so much one from the other, horseflesh 
 is usually boned before being offered for sale as beef. It is also 
 more oily than beef, and moreover coarser and darker, without the 
 fat layers in the muscle ; it has, besides, a characteristic odour. 
 At times, peculiarities of fodder or pasture may give a dis- 
 agreeable odour to meat, but it is exceptionally rare for any distinct 
 ill effects to result from eating such. Similarly, the meat from 
 animals recently physicked may be less palatable, and is of course 
 proportionately deteriorated in quality. At other times meat may 
 be coarse, tough, and stringy, especially if the animal be aged ; 
 such meat should not be regarded as unfit for food simply on 
 account of age, A cow may be slaughtered as late as twenty years 
 of age, though in such a case the carcase would be extremely thin. 
 The best beef is from oxen of from five to six years of ag£. As 
 sheep are not used for milking in this country, aged ewes are rarely 
 seen in the meat markets ; old rams, however, are by no means 
 uncommon, yielding, of course, poor mutton. Ram mutton is 
 coarse, and often emits an unpleasant smell. 
 
 Diseased Conditions of Meat. — The flesh of over-driven 
 animals is said to be injurious, but perhaps the most common 
 condition which renders flesh unfit for human consumption is 
 putrefaction. In marked emaciation from disease, but not 
 mere leanness, in glanders, anthrax, generalised tuberculosis, 
 measles and trichinosis, the whole carcase of the animal should be 
 condemned. Local inflammatory conditions, early and limited 
 actinomycosis, localized tuberculosis, or the presence of liver 
 fluke and echinococci do not justify the condemnation of the 
 whole carcase, if the rest of the flesh is firm and of good colour. 
 In these cases, it will suffice to cut freely away on the diseased 
 parts. 
 
 The following are the chief diseases met with or likely to occur 
 
DISEASES OF ANIMALS USED FOR FOOD. 
 
 157 
 
 in either home-bred or imported animals, and which may be re- 
 garded as more or less rendering their flesh unfit for man's 
 food : — 
 
 In oxen 
 and sheep 
 
 f Cattle plague. 
 Pleuro-pneumonia. 
 
 I Boils. 
 Black quarter. 
 Splenic fever. 
 Sheep pox. [losis). 
 
 Consumption (tubercu- 
 Actinornycosis. 
 Joint-ill or rheumatism. 
 Foot-and-mouth disease. 
 Liver-fluke. 
 VHoof-rot. 
 
 /Pleuro-pneumonia. 
 
 Swine fever. 
 
 Anthrax. 
 / Foot-and-mouth disease. 
 " & \ Consumption(tuberculosis). 
 
 Quinsy. 
 
 ICysticerci (measles). 
 
 \Trichinae. 
 
 T , (Glanders. 
 
 In horses < ^ 
 
 trarcy. 
 
 A few of these affections are parasitic diseases in which the 
 meat or flesh is infected with the young of worms so as to render 
 it unfit for the food of man. With regard to the hurtfulness or 
 not of the flesh of animals affected with general diseases, some 
 variety of opinion exists. The general symptoms resulting from 
 the consumption of such • meat are mainly vomiting, diarrhcea, 
 fever, and more or less prostration. In the majority of cases of 
 disease, the meat is dark and moist, usually altered in consistency. 
 
 Although there is reason to think that, with few exceptions, 
 harmful products in the flesh of animals which have died from any 
 diseases such as cattle plague, pleuropneumonia, foot and mouth 
 disease, rheumatism, glanders or farcy are rendered innocuous by 
 exposure to the temperature of cooking, still the safest course is 
 to reject for food the flesh of all animals affected with any acute 
 or specific disease. The great majority of outbreaks of " food- 
 poisoning" are due to infection of the food with bacilli of the 
 Gartner group, a class of bacilli closely related to those of 
 dysentery and enteric fever in man. The diseases of animals 
 caused by or closely allied to infections by bacilli of the Gartner 
 group are swine fever and certain septicaemias and dysenteric 
 diseases of calves and cattle. Sometimes these outbreaks of 
 food-poisoning are instances in which the infecting bacilli have 
 reached the meat or food from outside sources, that is either by 
 contamination by " carriers " of infection, either human or animal, 
 or by fouling by rats or mice suffering from typhus murium, a 
 disease in which the infecting bacillus belongs to the Gartner 
 group. Putrefactive changes in meat were once thought sufficient 
 to account for illness associated with outbreaks of food-poisoning. 
 This is not the case, and what is so often called ptomaine 
 poisoning is now recognized to be due to infection with the 
 Gartner bacilli, the bacilli themselves producing toxins or 
 
158 FOOD. 
 
 diffusible poisons which are the cause of the illness. These 
 toxins are little if at all affected and modified by cooking. 
 Frequently the mischief is done after cooking and during 
 handling and storage. 
 
 Owing to its widespread diffusion among animals killed for 
 food, tuberculosis or consumption is a constant source of danger 
 to meat consumers. Commonly called by butchers " the grapes " 
 or pearl disease, it is common among oxen and pigs but less so 
 among sheep. The disease is marked by the presence of small 
 white tumours or pearls. These occur mainly on or near the 
 surface of the lungs and on the inside of the chest walls, but they 
 may also be scattered through the lungs, liver, and general parts 
 of the body; this latter condition is rare. Tuberculosis is now 
 known to be associated with, and caused by a minute organism 
 called the tubercle bacillus, which is readily carried from one part 
 of the body to another, and consequently is a disease com- 
 municable from one of the lower animals to man. The Royal 
 Commission on Tuberculosis (1898) advised that the entire 
 carcase and all organs should be seized in case of — 
 
 (1) Miliary tuberculosis of both lungs; 
 
 (2) Tuberculous lesions on the pleura and peritoneum; 
 
 (3) Tuberculous lesions in muscle or intermuscular lymphatic 
 
 glands ; 
 
 (4) Tuberculous lesions in any part of an emaciated carcase. 
 But only the tuberculous parts need be seized if the lesions are 
 
 confined to — 
 
 (1) The lungs and thoracic lymphatic glands; 
 
 (2) The liver ; 
 
 (3) The pharyngeal lymphatic glands ; 
 
 (4) Any combination of the above if the lesions are collectively 
 
 small in extent. 
 
 They also advise that foreign dead meat with " stripped " 
 pleura should be seized ; and that in the case of the pig the whole 
 carcase and organs should be seized if tuberculous deposit in any 
 degree be found. These views have been confirmed by the 
 Report of the Commission in 1907. 
 
 Mention has already been made that the flesh of animals used 
 as meat is frequently affected with parasites. In oxen — that is, in 
 beef— the parasite, present occasionally, is what is called the 
 Cysticercus bovis. It consists of a head or scolex of a tapeworm 
 having attached to it a cystic expansion. Meat containing this 
 cysticercus gives rise in man to a tapeworm called the Tcenia 
 medioca?iellata. A detailed account of this parasite and its life 
 history is given in a subsequent chapter. One of the most 
 common hydatids is the Echinococcus veterinoriwn. This is the 
 
DISEASES OF ANIMALS USED FOR FOOD. 1 59 
 
 hydatid of the tape-worm Tenia echinococeus which inhabits the 
 intestines of the dog. These cysts may be localized in any organ 
 of the body, but most largely in the liver. The cysticercus tcenia- 
 collis or hydatid form of the Tcenia marginata, which is the tape- 
 worm of dogs, is often found in large numbers in the abdominal 
 cavity of sheep and pigs. These cysts vary in size from a pea to 
 a tennis ball, and are found usually adhering to the folds of the 
 peritoneum. Sheep also suffer from the hydatid or cystic form of 
 the Tcenia ccenurtis^ which also inhabits the intestines of dogs, and 
 is the one which gives rise to the condition known as " sturdy " in 
 sheep. It is usually lodged in the brain of the sheep. Unless 
 the animal be much emaciated, the carcase of the animal with the 
 exception of the head is fit for food. 
 
 in sheep, the chief and most common parasite is the fluke^ which 
 is a kind of worm, in shape very like a sole fish, only measuring 
 1 to 1 J inches in length and about f inch in width. It infests the 
 liver of sheep and occasionally oxen, giving rise to the disease 
 of sheep called " the rot." As cooking always kills the fluke, few 
 cases of disease from this parasite are known in man ; but as its 
 presence in a sheep's liver usually causes the animal to be in bad 
 health, the flesh of " rotted " sheep must, as a rule, be regarded as 
 unsound and unfitted for food. Occasionally, both oxen and 
 sheep are affected with the cyst form or cysticercus of the Tcenia 
 ec/iinococcus, which is a tapeworm whose adult form only affects 
 dogs and wolves. In man, this cyst gives rise to echinococcur. 
 or hydatid disease. A more detailed account of this parasite is 
 given in Chapter VIII. 
 
 The presence of cysticerci in meat is generally visible to the 
 naked eye ; they are so numerous sometimes as to cause the flesh 
 to crackle on section, or even feel gritty : their real nature is 
 readily seen when the meat is placed under a microscope with 
 low power. 
 
 The pig is infested with two parasites, both of which exist in 
 the flesh or pork. One is the Cysticercus cellulosce^ which, existing 
 in the pig's muscle as a cyst of the size of a pea or small marble, 
 constitutes the affection known as " measles," and this measly 
 pork when eaten gives rise to a tapeworm in man called the 
 Tce?iia solium. The cysticerci of pork are killed by a temperature 
 o! 140 F., and if pork were always properly cooked this would 
 render them harmless ; but as no dependence can be placed upon 
 the meat being sufficiently heated and cooked, measly pork needs 
 to be always condemned as unfit for food. The other parasite 
 of the pig is the Trichina spiralis. This is a very small immature 
 worm, which is found coiled up inside ovoid cysts, which, of the 
 size of jq inch, lie imbedded in the pig's muscle. When thus 
 
l6o FOOD. 
 
 affected, the pork shows a number of small white specks between 
 the muscle bundles, and is said to be trichinosed. As will be 
 explained subsequently, the eating of this trichinosed pork gives 
 rise to the disease called trichinosis in man. Such diseased pork 
 is, of course, unfit for food. Pimply gut is characterized by the 
 presence in the wall of the small intestine of the pig of small 
 round dark-coloured nodules. Each nodule contains the larvae 
 of the round worm CEsophagostomum columbianum. The con- 
 dition is important, chiefly in connection with the use of sausage 
 skins. 
 
 Onchocerciasis is a condition due to a worm • known as the 
 Spiroptera reticulata, and has recently been found in Australian 
 meat imported frozen into this country. The parts of the carcase 
 generally found to be affected are the fore quarter, the brisket, 
 and the hind quarter. The nodules are oval, about one inch in 
 length and half-inch wide, and are formed by the Spiroptera, 
 which probably are introduced by a biting insect. The worm 
 does not long survive the death of the host, so that infection 
 to man is not probable. 
 
 Fish. — As a class, fish vary much in digestibility, this depend- 
 ing practically on the amount of fat they contain. The fatter a 
 fish is the more digestible its flesh. Of the fat group of fishes the 
 best are salmon, herring, mackerel, eels, and sprats ; of the non- 
 fatty, the cod is the most commonly consumed specimen. Of the 
 various shell-fish, oysters eaten raw are almost self-digestive, but 
 lobsters and crabs are not only foul feeders, and as such liable 
 to give rise to ill effects when eaten, but also notoriously 
 indigestible. The same may be ■ said of mussels, these fish in 
 particular being at times extremely liable to cause poisonous 
 symptoms, especially when taken from stagnant water to which 
 sewage has access. 
 
 To be at their best and wholesome, fish should be in season. 
 During spawning a fish gets flabby and thin, and during this period 
 is rightly regarded as being " out of season " and unfitted for food. 
 A few fish are peculiar in their breeding, such as brill, dory, 
 lobsters, plaice, prawns, soles, shrimps, turbot, and red mullet, 
 which are in season all the year round. Oysters are not in season 
 during the four months spelt without an r. 
 
 By the Freshwater Fisheries Act, 1878, it is enacted that, 
 subject to special exemption by the Board of Trade for eels, 
 pollen, trout, and char in certain fishery districts, from March 15 
 to June 15 shall be a close time for all fresh- water fish. 
 
 As in the case of animals, fish when eaten should be fairly 
 fresh. A fresh fish is firm and stiff; the drooping or not of its 
 tail is a fair criterion of freshness in a fish. Flat fish keep better 
 
FISH. l6l 
 
 than herrings or mackerel. Cod, haddock, and whiting keep the 
 best, particularly if rinsed with salt water and stored in a cool 
 place. All fish intended for food should be unbruised, unbroken, 
 and clean. If the scales are dull and damaged, it is very sugges- 
 tive of either ill usage or staleness ; softening in places indicates 
 the same. Fish are sometimes affected with a parasite in the 
 form of a cysticercus. This, when eaten imperfectly cooked, 
 gives rise to a tapeworm called the Bothriocephalus latus. These 
 diseased fish are rare in this country, but common in Russia, 
 Poland, Sweden, and Switzerland. 
 
 Although the great group of fishes yields a larger number 
 of species used as food by man than either birds or animals, and 
 although there are but few fish in British waters which may not 
 be eaten with advantage, still many prejudices exist with regard 
 to their use. This is much to be regretted, as fish are most 
 valuable and important articles of nourishment; if perhaps not 
 possessing the satisfying and stimulating properties that belong to 
 the flesh of birds and quadrupeds, still the health and vigour of 
 the inhabitants of fishing towns, where fish often forms the only 
 kind of flesh food consumed, show that it is capable of main- 
 taining the body under active conditions of life. The fish-eating 
 races and classes are remarkably strong and healthy. For the 
 sick or weakly, in whom the powers are too feeble to digest 
 the stronger kinds of animal food, fish possesses valuable 
 properties. 
 
 The processes of drying, pickling, salting, and smoking are 
 employed for the preservation of fish. Each process considerably 
 lessens its digestibility, and therefore unsuits it for either the 
 dyspeptic or the invalid. 
 
 Eggs. — From the fact that the young chick is developed 
 from it, an egg necessarily contains all that is required for the 
 construction of the body. On this account eggs are often spoken 
 of as typical natural foods. Protein matter "is largely present, 
 under the form of albumin, both in the white and yolk. Fat 
 exists as an oil in the yolk. Carbohydrates exist in the form of 
 minute quantities of a saccharine matter, and water and salts 
 complete the list. The hen's egg usually weighs 2 ozs., but those 
 of ducks and some sea-fowl weigh more. The shell of an egg 
 constitutes some 10 per cent, of the total weight; the white, 
 60 per cent. ; and the yolk, 30 per cent. The white of egg con- 
 sists chiefly of albumin, with traces of fat and salt ; the yolk 
 consists largely of fat and salts, with a small amount of globulin. 
 Ducks' eggs contain generally more fat than those of hens. Eggs 
 offer a convenient and concentrated article of diet, rich in fat and 
 protein, but are at times indigestible, particularly if overcooked. 
 
 G 
 
162 
 
 FOOD. 
 
 They are conveniently preserved by exclusion of their contents 
 from the air by immersing them in lime water or " water glass " 
 (silicate of soda). Their condition as to freshness is readily 
 determined by dissolving 2 oz. of common salt in a pint of water ; 
 in this solution a good egg will sink, while a stale or bad one 
 floats. Eggs may also be examined by looking at them in the 
 dark against the strong light of a lamp. A fresh egg appears 
 unclouded and almost translucent ; a bad one is opaque and 
 dark. 
 
 Milk. — Milk not only constitutes the chief diet for children up 
 to some eighteen months of age, but also enters very largely into 
 the food of adults. All milk may be regarded as nothing more 
 than an emulsion of fat containing proteins, salts, and carbo- 
 hydrates in solution in water. The average composition of milk 
 per 100 parts, from the chief sources as used by man, is shown in 
 the following table : — 
 
 Kind of milk. 
 
 Specific 
 gravity. 
 
 Total 
 
 solids. 
 
 Proteins. 
 
 Fats. 
 
 Carbo- 
 hydrates. 
 
 Salts. 
 
 Water. 
 
 Human . 
 
 I027 
 
 12-60 
 
 2*29 
 
 3-Si 
 
 6-20 
 
 0*30 
 
 87-40 
 
 Cow's 
 
 I032 
 
 I283 
 
 3'55 
 
 3*69 
 
 4-88 
 
 071 
 
 87-17 
 
 Mare's 
 
 I03S 
 
 9*21 
 
 2*00 
 
 I'20 
 
 5-65 
 
 0-36 
 
 90-79 
 
 xi-SS S * • • • 
 
 IO26 
 
 10*40 
 
 2-25 
 
 1-65 
 
 6 - oo 
 
 050 
 
 89-60 
 
 Goat's 
 
 IO32 
 
 14-30 
 
 4'30 
 
 478 
 
 4-46 
 
 075 
 
 8571 
 
 Buffalo's . . . 
 
 IO32 
 
 18-60 
 
 6-u 
 
 7 '45 
 
 4-17 
 
 0-87 
 
 81-40 
 
 Although all the above are used at times by man for food, the 
 most important kinds undoubtedly are human milk and cow's 
 milk; and these differ from each other in some essential par- 
 ticulars. As seen by the preceding table, while there is more 
 carbohydrate in human milk than in cow's, the reverse is the case 
 with the proteins and salts ; the fat being much the same in them 
 both. Ass's milk, except in regard to its fat, is most like human 
 milk, but mare's milk contains even less fat and protein than the 
 ass's ; while, on the other hand, milk from both the goat and 
 buffalo are very rich in fat. 
 
 The proteins of milk consist largely of casein; but there is 
 also some albumin, with traces of globulin. The casein probably 
 exists in milk in combination with phosphate of lime, which helps 
 to keep it in solution. Pure casein is now prepared on a large 
 scale, and constitutes the basis of a number of dietetic prepara- 
 tions, such as Plasmon, Protene flour, Sanose, Nutrose, and 
 Eucasin. The nutritive value of these preparations is high, as 
 they contain fully 90 per cent, of pure protein. In these forms 
 
MILK. 163 
 
 casein is digested easily, and capable of replacing all other forms 
 of protein in the diet. 
 
 The salts of milk are both numerous and various, being com- 
 posed really of all the mineral constituents necessary to the 
 growing body. 
 
 The fat of milk is nothing more than minute oil globules 
 suspended in the milk, and which, upon standing, rise slowly to 
 the surface, forming cream. One part of cream is said to cor- 
 respond to 0*2 of fat roughly; the proportion of cream yielded 
 by a pure milk varies, but may be said to average 10 per cent., 
 being as high as 14 in some cases, and as low as 6 in others. 
 The amount found in a given time is no measure of the richness 
 of the milk ; water added to milk causes a more rapid separation 
 of the cream. When milk is subjected to centrifugal action, as 
 in the separator so largely used now in commercial dairies, a 
 much larger proportion of cream is obtained than by the mere 
 skimming process. As a result of this, skim milk contains 1 per 
 cent, of fat, while separated milk has practically none. 
 
 The carbohydrate of milk is a peculiar sugar, somewhat like 
 cane-sugar, and called lactose, or sugar of milk. This body, like 
 all other sugars, undergoes fermentation under the influence of 
 micro-organisms, and one especially, called the Bacterium lactis, 
 abounds in dairies and other places where milk is kept. This 
 micro-organism converts the milk-sugar into lactic acid, while at 
 the same time the proteins are partly decomposed and partly 
 coagulated, the milk itself becoming sour with enclosure of the 
 fat in the coagulated casein. Many other micro-organisms pro- 
 duce coagulation of milk, notably the Bacillus butyricus of butyric 
 acid fermentation. Some others have the power of changing the 
 colour of milk, particularly if lactic acid fermentation has occurred 
 In nearly all these cases the milk becomes ropy and stringy, also 
 it is apt to cause diarrhoea, and is unsuited for food. Alcoholic 
 fermentation of the* milk-sugar can also be set up by certain 
 micro-organisms. "Koumiss" is the result of the alcoholic 
 fermentation of mare's milk, and " Kefir " is that of cow's, goat's, 
 and sheep's. After the lactic acid fermentation of milk has set 
 in, the casein gradually decomposes, and, during the early de- 
 composition of the proteins, very frequently highly poisonous 
 compounds are formed, such often being the cause of the 
 violent poisonous effects which at times are produced by ice- 
 creams and other articles of food into the making of which milk 
 enters. 
 
 Humanized cow's milk is much used in the feeding of infants. 
 Its essential feature is the removal of the excess of caseinogen 
 from the cow's milk while retaining the soluble and easily digested 
 
1 64 FOOD. 
 
 lact-albumin. A suitable method of preparation is : allow a pint 
 of milk to stand in a cool place for three hours, then remove by 
 skimming the cream which has risen to the top. Divide the 
 skimmed milk into two equal parts. To one part add a small 
 piece of rennet and strain off the curds when formed, leaving the 
 whey. Heat this whey to 150 F., to destroy the rennet ferment, 
 then add the other half of the skimmed milk and the cream. Add 
 175 grains of lactose or milk sugar to the mixture and sufficient 
 lime-water to render the whole faintly alkaline. Then heat to 
 1 5 8° F. for twenty minutes. The use of whey in this method 
 makes a better emulsion with the fat (cream) than ordinary water 
 and also yields a fine curd. 
 
 Although boiling undoubtedly destroys bacteria and other 
 micro-organisms in milk, it affects seriously the physical and 
 nourishing qualities of this food. Boiling of milk produces 
 coagulation of the lact-albumin, some obscure changes in the 
 sugar, and greater coalescence of the fat globules ; at the same 
 time, the proteins are modified, and rendered apparently less 
 digestible, the salts are less soluble, and the vitamines are 
 destroyed. The chief chemical change in the salts is probably 
 the conversion of the soluble bi-citrate of calcium into a less 
 soluble tri-citrate. Most authorities agree that boiled milk has 
 less nutritive value than that which is fresh, and that the indis- 
 criminate feeding of infants for months upon carelessly boiled or 
 heated milk is productive of much harm. A discrimination needs 
 to be made not only as to means of heating milk, but also between 
 degrees of heat to which it is raised. It is known that up to 
 70 C. no apparent changes are produced in milk; at 70 C. the 
 albumin begins to be affected, not actually coagulated, but con- 
 verted into a form which is easy of precipitation by acids, sulphate 
 of magnesium, and other precipitants of casein. At 8o° C. milk 
 tends to alter in flavour and the vitamines undergo retrograde 
 changes ; at 85 C. the calcium citrate is thrown out of solution. 
 The remedy seems to be to avoid routine boiling of milk, but to 
 heat the milk in a water bath or bain-marie to not more than 
 75° C. (160 F.), maintaining it at that temperature /or twenty 
 minutes or so, and then cooling it to a temperature as near 15 C. 
 (32 F.) as possible. This is the method of so-called "pasteuriza- 
 tion." It may entail more trouble for mothers and nurses, but the 
 recognition of the principle is the only basis for sound practice, 
 provided that it be borne in mind that the pasteurized milk 
 has somewhat lessened keeping properties than the untreated 
 milk. 
 
 The actual composition of cow's milk is influenced by not 
 only the breed of the animal, but also by the kind of feeding 
 
MILK. 165 
 
 and the time of calving and milking. The effect of diet is largely 
 shown by the increase of sugar found in the milk of cows fed upon 
 fodder rich in carbohydrates, such as carrots and beetroot. The 
 addition of protein in the diet raises the casein, but not the fat. 
 The colostrum, or milk of cows recently calved, is poor in sugar, 
 but rich in casein and albumin. The first part of a yield during 
 milking, known as fore milk, is deficient in fat, but the latter part, 
 called the strippings, is very rich in cream. 
 
 It is well known that in human beings, bitters and purgatives, 
 if taken by the mother, act upon infants taking the milk. Diseased 
 potatoes and turnips in the food of cattle, without actually 
 affecting the goodness of milk, often cause it to smell and taste 
 unpleasantly ; other fodders often produce poisonous effects, as in 
 goats feeding upon meadow saffron inducing severe diarrhoea, or 
 in the case of cows affected with "trembles," due to eating the 
 Rhus toxicode?idron, their milk gives rise to vomiting and consti- 
 pation. Milk allowed to stand long in warm dirty rooms has a 
 remarkable power of absorbing bacteria, rapidly becomes sour and 
 objectionable, and is a fruitful cause of diarrhoea occurring among 
 the children of the poor. 
 
 Milk may be affected by diseased conditions of the cow or the 
 animal yielding it. In foot-and-mouth disease, cow's milk varies 
 very greatly; but a constant feature of such milk is the great 
 excretion of serum albumin. Milk of cows affected with foot- 
 and-mouth disease should never be consumed as food, as it may 
 cause disease in human beings. Tuberculosis in cows un- 
 doubtedly affects the milk yielded by them, particularly when the 
 teats are tuberculous, and such milk, if consumed, is the undoubted 
 cause of infection by the same disease (consumption) in man. 
 There is much to suggest that a considerable amount of tubercular 
 infection through milk takes place in infancy and early childhood. 
 There is reason, too, to think that both scarlet-fever, diphtheria, 
 and enteric fever, and also cholera, are in many cases propagated 
 by means of milk, the milk becoming infected, either by foul 
 water used in the cleaning of utensils or for intentional dilution, 
 or by handling by human beings who were or are at the time 
 sufferers from one or other of these diseases. The remedy is 
 obviously to subject any doubtful milk to pasteurization or to a 
 temperature of at least 70 C. for twenty minutes, as by this 
 procedure the specific micro-organisms of tuberculosis, diphtheria, 
 enteric fever, dysentery, cholera, zymotic diarrhoea and other 
 infective diseases are destroyed. 
 
 Adulterations of Milk. — The chief adulterations of milk are 
 the additions of water and the removal of cream ; while carbonate 
 of soda, salt, formaldehyde, boracic acid, or salicylic acid, glycerine 
 
1 66 FOOD. 
 
 and starch are added, either to preserve the milk or to mislead the 
 analyst. A common procedure is to remove part of the cream, a 
 procedure which would naturally raise the specific gravity, and then, 
 by adding water, to bring the specific gravity down to the normal. 
 The addition of water lowers the specific gravity, the fat, solids not 
 fat, and the salts per cent. This added water can be sometimes 
 detected by taking the specific gravity of the milk by means of a 
 lactometer, which should be done at a temperature of 6o° F. ; if 
 at a higher or lower temperature than this, i° of specific gravity 
 must be added or deducted for every io° of heat. In good milk, 
 the specific gravity is from 1028 to 1034 ; while, in creamed milk, 
 it is from 1033 to 1037 ; that is to say, it is lowered by watering 
 and increased by skimming. This taking of the specific gravity 
 alone is not to be relied upon as an index of the character of the 
 sample, but should be taken in conjunction with the facts relating 
 to the fats and total solids. 
 
 The total solids can be estimated by taking a weighed quantity 
 of milk, and evaporating it slowly to dryness, and re-weighing. 
 Usually 2 -5 c.c. of milk are taken for this estimation, and in 
 good milks the total solids should not be less than 12 percent. 
 The fat in a good milk should not be below 3 per cent. ; it is 
 conveniently estimated by mixing a weighed quantity of milk with 
 a weighed amount of burnt gypsum, and evaporating to dryness. 
 The fat is extracted from the residue by ether, and the ether then 
 evaporated, when the residue is again re-dried, re-weighed, and 
 calculated out as fat per cent. For the more rapid and routine 
 estimation of fat in milk samples, the employment of a centri- 
 fugalizing machine and the use of the Leffmann and Beam pro- 
 cess will be found satisfactory. Fifteen c.c. of the milk are 
 placed in the special glass bottle supplied with the centrifugalizer ; 
 3 c.c. of a mixture of equal parts of fusel oil and strong hydro- 
 chloric acid are added, and then 9 c.c. of pure sulphuric acid. 
 These latter must be added slowly, about 1 c.c. at a time, and 
 the contents of the bottle carefully shaken. The milk will gradu- 
 ally assume a chocolate colour passing to a deep brown, and at 
 the same time much heat be generated. When the whole of the 
 9 c.c. of acid have been added, the contents of the tube or bottle 
 must be filled up to the zero mark with a hot and freshly made 
 mixture of one part of strong sulphuric acid with two of water. 
 The bottle should be placed in one of the carriers of the machine, 
 and whirled for at least two minutes. If only one sample of 
 milk is being tested, the opposite carrier must be balanced by a 
 corresponding bottle filled with dilute sulphuric acid. A milk 
 poor in fat may need centrifugalizing for four or five minutes, but 
 usually two minutes is enough : very rapid rotation is not necessary. 
 
MILK. 167 
 
 On stopping the centrifugalizer and taking the bottle out of the 
 carrier, the fat will be seen to have separated out as a layer on the 
 top, and as the bottle is so made that each mark represents 1 per 
 cent, of fat, the total percentage ot fat in the sample is readily 
 read off. This method is subject to an error of about o*i per 
 cent., but its rapidity and ease render it a valuable and reliable 
 means of fat determination. The amount of fat so determined 
 deducted from the total solids gives the " solids not fat," and as 
 the result of many analyses, these are found, with very rare 
 exceptions, not to fall below 8*5 per cent. Hence this amount is 
 adopted as a standard, and if a given milk sample contains x per 
 cent of solids not fat, and x be less than 8*5, we are justified in 
 presuming that, however poor the milk may have been to begin 
 with, it must now have added water in it. Thus, presume a 
 given sample of milk has yielded 35 per cent, of fat, and 10*5 
 per cent, of total solids. The solids not fat are obviously 
 7 per cent., and working upon the above-mentioned minimum 
 standard of 8*5 for solids not fat, we get the following formula : 
 100 X 
 
 7 
 
 - = 82*35 parts of original or genuine milk in a 100 ; or, in 
 
 8-5 
 other words, over 1 7 per cent, of water may be presumed to have 
 
 been added to the sample. The ash of a good milk rarely falls 
 
 below 07 per cent., and accepting that as a minimum standard, a 
 
 similar equation can be stated, if the observed amount of ash be 
 
 known, as a means of calculating the degree of purity of any 
 
 particular milk. The ash of milk is, of course, estimated by 
 
 incinerating the total solids of a given bulk of milk, weighing and 
 
 expressing as a percentage. 
 
 Sugar in milk is easily determined by first precipitating the 
 
 casein, by means of acetic acid, from 10 c.c. of milk ; filtering, 
 
 and then diluting the filtrate or whey with distilled water to 
 
 100 c.c. This diluted whey contains the lactose or milk-sugar 
 
 in solution, and is next treated with a solution of copper until all 
 
 the copper is reduced to red suboxide, and no blue colour remains 
 
 in the liquid. The copper solution is so made that 10 c.c. are 
 
 decomposed by 0*0667 grm. of lactose. 1 If, say, 15 c.c. of a 
 
 ten-times diluted whey are required to reduce to c.c. of copper 
 
 solution, then -}f, or 1*5 c.c. of the original milk are needed 
 
 1 Take of pure copper sulphate 34*64 grms., and dissolve in 500 c.c. of 
 distilled water ; this is stock solution A. Take also 173 grms. of the tartrate 
 of sodium and potassium, with 56 grms. of caustic soda, and dissolve in 500 
 c.c. of distilled water ; this is stock solution B. When required for use, take 
 5 c.c. of each solution and mix. One c.c. of this solution is reduced by 5 
 mgms. of either glucose or inverted sugar ; and by 6*67 mgms. of milk-sugar 
 or lactose. 
 
1 68 FOOD. 
 
 to reduce that amount of copper solution, and 0-0667 ga- 
 lactose -r i*5 = 0*0445 grm. of lactose in 1 c.c. of milk, or 4*45 
 
 per cent. 
 
 The presence of added glycerine in milk can usually be 
 detected by the exceptional sweetness of the dried solids, but for 
 the detection of such preservatives as boric acid, salicylic acid, 
 sodium carbonate, and formaldehyde in milk, the following tests 
 need to be applied : — 
 
 Boric Acid. — Reduce 25 c.c. of the dried milk to an ash 
 slowly in a capsule, add a few drops of hydrochloric acid, suffi- 
 cient to render it distinctly acid, and then 25 c.c. of distilled 
 water. Now dip strips of turmeric paper in the mixture and dry 
 them over a flame. If boric acid be present the turmeric paper 
 will turn a crimson red, which on the further addition of sodium 
 carbonate turns blue. 
 
 Salicylic Acid. — Agitate 10 c.c. of the milk in a test tube with 
 0-5 c.c. of dilute sulphuric acid, so as to thoroughly break up the 
 clot and produce a homogeneous mixture. Next shake with 
 10 c.c. of ether, allow this to separate, and transfer to either a 
 capsule or another test tube ; slowly evaporate the ether at say 
 75 C, and then dissolve any salicylic acid which may be present 
 in the residue by boiling with 10 c.c. of rectified spirit. _ Now add 
 some ferric chloride solution and shake. If salicylic acid be 
 present a violet colour will be produced. 
 
 Sodium Carbonate. — Mix 10 c.c. of milk with 10 c.c. of 
 rectified spirit in a test-tube, and then add two or three drops 
 of a weak solution of rosolic acid, made by dissolving 1 grm. 
 in 25 c.c. of alcohol, and diluting with distilled water to a 
 litre. If the alkali be present in the milk, a rose-pink tint 
 
 appears. 
 
 Formaldehyde. — Place about 10 c.c. of the milk in a test-tube, 
 add to it 2 c.c. of a 10 per cent, solution of caustic potash and 
 1 c.c. of saturated solution of phloroglucine. If formaldehyde 
 be present a fleshy pink colour is produced. 
 
 The question of preservatives in milk and milk products has 
 long been a serious matter as affecting the national welfare. 
 Opinion is divided as to the actual harm resulting from the use 
 of very small quantities of preservatives in food, but modern 
 methods of cleanliness, storage, and transit, if properly applied, 
 should render the use of preservatives unnecessary even for so 
 rapidly decomposable a food as milk. The practice of using 
 preservatives in food leads to uncleanly methods, and is often the 
 means of rendering saleable an unwholesome food. The P.H. 
 (Milk and Cream) Regulations, 191 2, prohibit the use of 
 preservatives in milk, but define the conditions under which 
 
ADULTERATION OF MILK. 1 69 
 
 preservatives may be used in cream. The expression "milk" 
 includes separated, skimmed, condensed, and dried milk; but so 
 as not to interfere with the trade in condensed milk, it is laid 
 down that neither cane nor beet sugar shall be regarded as a 
 preservative, or a thickening substance. The restriction on the 
 use of preservatives in cream is as follows : " No person shall add 
 or order or permit any other person to add any thickening 
 substance to cream or preserved cream, or any preservative 
 substance to cream containing less than 35 per cent, by weight of 
 milk fat or to cream containing 35 per cent, or more by weight of 
 milk fat any preservative substance other than boric acid, borax, 
 or a mixture of these preservative substances, or hydrogen 
 peroxide in amount not exceeding o*i per cent, by weight in any 
 case in which the cream is intended for sale for human con- 
 sumption." Dealers in cream preserved in a manner which does 
 not contravene this regulation must attach a label to declare that 
 the cream is preserved, and to state the name of the preservative. 
 In tea-shops and refreshment-rooms the cream jugs are not 
 required to be labelled, provided in each room a conspicuous 
 notice is affixed indicating that the cream supplied is preserved 
 cream, or if a statement to that effect is printed on the bill 
 of fare. 
 
 An amending Order, 19 16, allows boric acid to be added to 
 cream containing more than 35 per cent, by weight of milk fat, 
 provided the amount of boric acid so added does not exceed 
 o'4 per cent, by weight of the preserved cream. Every receptacle 
 containing preserved cream must be labelled " Preserved Cream 
 containing Boric Acid not exceeding — per cent. Not suitable 
 for Infants or Invalids." These amending regulations have been 
 in abeyance and will not take effect till 1921. 
 
 The Board of Agriculture under the Sale of Milk Regulations, 
 1 90 1, laid down certain fixed limits or standards as to the 
 composition of milk. By these regulations a presumption is 
 raised that milk (not being sold as skimmed or separated, or 
 condensed milk) is not genuine unless it contains 3 per cent, of 
 milk fat and 8-5 per cent, of milk solids other than milk fat. 
 Further, where a sample of skimmed or separated milk (not being 
 condensed milk) contains less than 87 per cent, of milk solids 
 other than milk fat, it shall be presumed that the sample is not 
 genuine. By this order the principle of standards for food 
 becomes officially recognized. 
 
 A number of excellent brands of condensed milk are now on 
 the market. As a rule condensed milks are free from pre- 
 servatives. In the sweetened milks the added cane sugar is 
 sufficient to check the growth of bacteria, and in the unsweetened 
 
170 FOOD. 
 
 varieties the milk has been sterilized at temperatures over ioo° C, 
 amply sufficient to destroy any disease causing micro-organisms. 
 The full cream unsweetened condensed milks are the more 
 suitable for feeding human infants, but, owing to the high 
 temperatures to which the original milk has been exposed in 
 manufacture of the condensed article, the essential rickets and 
 scurvy preventing vitamines have been destroyed. We believe 
 that this objection does not hold good for the various brands of 
 dried milk, of which several are in general use. Only the full- 
 cream dried milks should be used for infant feeding. We have 
 reason to think that the best brands retain the essential vitamines 
 so characteristic of the normal fresh milk of the cow. The dried 
 milk powder keeps well if stored in a dry and properly ventilated 
 place. The chief objection to the use of dried milk is the 
 difficulty of reconstituting a satisfactory representation of the 
 fresh article. It is by no means easy to make a good emulsion 
 with water from dried milk powders, and until this difficulty is 
 overcome there will remain always a certain objection to them. 
 For travellers and others similarly situated, dried milk is an ideal 
 article. 
 
 We cannot leave this subject of milk without calling attention 
 to the urgent need of a reform of the country's milk supply. 
 Associated as it closely is with the problem of infant mortality it 
 constitutes a national question of the first importance. The 
 problem of milk supply is really threefold, namely, (i) to prevent 
 the sale of milk derived from tuberculous cows and to safeguard 
 against initial pollution at the time of milking; (2) to protect 
 milk from subsequent fouling, either during transit to or storage 
 in the home of the consumer; and (3) it must be produced at a 
 price which will bring it within the reach of the poor. To 
 prevent the first, attention must be directed to the farm. The 
 cows must be healthy, systematically inspected as to tuberculosis, 
 and housed in byres or sheds so planned and constructed as to 
 permit of these cattle remaining healthy. Further, the process of 
 milking must be carried on with scrupulous cleanliness of cows, 
 milkers, and all utensils. The second line of prevention must 
 ensure that milk, immediately after milking, be maintained at a 
 temperature not exceeding 40 F., and that as soon as possible 
 after cooling the milk be bottled, and the bottled milk be kept at 
 even a lower temperature, say 35 F., until it is delivered to the 
 consumer. By the precautions during milking the initial con- 
 tamination is minimized, and bottling would minimize home 
 contamination. The third essential, or safeguarding of price, can 
 only be obtained by the municipalization of the milk supply. 
 The present position of the law, and details as to the legal 
 
BUTTER. 171 
 
 provisions existing already for controlling milk supplies, are given 
 in Chapter XII. 
 
 Butter. — This really is the fat of milk clotted together, and 
 consists chiefly of neutral fats mixed with water and small amounts 
 of casein and salts. Average butter may be said to have the 
 following composition per cent.: Fat, 78 to 94; curd, 1 to 3 ; 
 water, 5 to 14 ; salt, o to 7. The flavour of a good butter is 
 due to butyric and caproic acids, which constitute about 8 per 
 cent, of the fat, the rest being composed of glycerides of oleic, 
 stearic, and palmitic acids. The water in a good butter should 
 not exceed 16 per cent., an excess lessens the keeping quality of the 
 butter ; it contains ordinarily in solution milk-sugar and the milk- 
 salts. Milk-blended butters should not contain more than 24 per 
 cent, of water. Common salt is usually present, but generally 
 added after the butter is made. Artificial colouring matters are 
 often present in butter, notably annatto, but it is harmless ; occa- 
 sionally starch is added to give weight, and may be recognized by 
 its blue reaction with iodine. Practically the only adulteration in 
 butter is the substitution of foreign fats, such as tallow, lard, palm- 
 oil, rape-seed oil, or cocoa-nut oil, for milk fat; and as a result 
 the analysis of a butter turns mainly upon the properties and 
 composition of the fat. 
 
 The amount of fat can be estimated by dissolving it in ether, 
 evaporating the ether solution, drying, and weighing. For the 
 detection of an admixture of foreign fats, several methods have 
 been proposed ; the principal being : (1) Taking the specific gravity 
 of the sample. That of water being unity, a pure butter usually has 
 a specific gravity of 0*911 to 0*913 ; an adulterated butter one of 
 0*902 to 0*904 ; and an artificial butter one as low as 0*859 to o'86i. 
 (2) Determining the melting-point of the fat after separation from 
 the other constituents. The melting-point of pure butter fat is 95 F., 
 but may vary ; the addition of animal fats, such as lard, raises the 
 melting-point, while vegetable fats, such as rape-seed oil, tend to 
 lower it. (3) Determination of the fixed fatty acids. This, though 
 rather a difficult process to do, is most generally relied upon. It 
 is based on the fact that when saponified with a caustic alkali such 
 as soda or potash, and then decomposed with hydrochloric acid, 
 the individual fatty acids which go to make up butter are obtained. 
 A certain number of these are soluble in water, and others are 
 not, and it is owing to the insoluble fatty acids obtainable from 
 butter differing in amount from those obtainable from other 
 animal fats that pure butter can be detected from artificial, the 
 figures being, that if the insoluble fatty acids are over 89 per cent, 
 there is an admixture of foreign fat. 
 
 Of artificial butters there are several ; but in their manufacture 
 
172 FOOD. 
 
 they are very similar, consisting really of a certain amount of 
 genuine butter mixed up with animal or vegetable fats, such as 
 lard, rape-seed oil, etc. By the Butter and Margarine Act, 1907, 
 all these artificial butters are ordered to be called and sold as 
 margarine^ while milk-blended butters must be sold under such 
 names as will disclose their nature and amount of contained 
 water. If made from pure animal fats, these artificial butters 
 have as high a nutritive value as pure butter. The average 
 melting-point is 86° F., and the insoluble fatty acids contained in 
 them are usually as high as from 92 to 95 per cent., as compared 
 with 88 or 89 per cent, in pure milk butter. 
 
 For adults, margarine is but little inferior in nutritive qualities 
 to butter, biit, being derived mainly from vegetable oils, it is 
 greatly deficient in fat soluble vitamines normally present in 
 animal fats, and, for this reason, cannot replace butter or dripping 
 in the dietary of the young. Margarine makes a palatable 
 substitute for butter as an article of diet, but it must not be sold 
 as butter. It is less digestible than butter and frequently contains 
 preservatives and colouring agents. 
 
 Cheese. — This is made from milk by the action of rennet, 
 which is commonly derived from the fourth stomach of the calf. 
 Cheese consists of coagulated casein, with varying proportions 
 of fat and salts. The different qualities of cheese depend mainly 
 upon whether they are made from pure milk, from skimmed 
 milk, or from a mixture of skim and whole milk. Thus, Cheddar, 
 double Gloucester, Cheshire, and some American cheeses are 
 made from whole milk, while Stilton is made from whole milk 
 to which cream is added. Dutch, Parmesan, Suffolk, and Somer- 
 setshire cheeses are made from skimmed milk. Cream cheese 
 consists of the fresh curd which has been moderately pressed ; 
 it is eaten without being allowed to ripen. When a cheese is 
 kept, it undergoes a change known as " ripening," which is essen- 
 tially a decomposition, whereby the casein undergoes a fatty 
 change, including the formation of lime salts of the fatty acids 
 and the production of a soluble compound of phosphoric acid 
 with casein, from the phosphate of lime usually present in milk. 
 
 As an article of diet, cheese is very useful, being particularly 
 rich in both protein and fat ; the only objection to it being its 
 occasional indigestibility. Its adulterations are unimportant, the 
 chief being starch, to give weight. On an average, the water in 
 cheese ranges from 20 to 35 per cent., the protein from 25 to 
 50 per cent., the fat from 12 to 20 per cent., and the salts some 
 3 to 6 per cent. Cheeses usually contain small amounts of milk- 
 sugar, lactic, and other organic acids. The richer kinds of cheese 
 are very liable to form the seat of growth of certain animal and 
 
CHEESE—VEGETABLE FOODS. 1 73 
 
 vegetable organisms. The maggots or larvae of a fly (Piophila 
 casei) are well known, so also is the cheese mite, or Acarus 
 domesticus. The mould on a cheese is composed of minute 
 vegetable organisms of the fungus tribe ; the red mould is 
 caused by Sporendoneiiia case/, and the blue mould by Aspergillus 
 glaums. 
 
 Vegetable Foods. — This large group, which includes a great 
 number of articles of diet, is chiefly remarkable for the fact that 
 although it supplies a certain quantity of protein and fat, its chief 
 functions are for the provision of carbohydrates, vegetable acids, 
 water soluble vitamines, and salts to the organism. Further, 
 owing to the large amount of water which vegetable foods take 
 up during cooking, they may also be said to supply a large 
 quantity of water to the body. The proteins of vegetables are 
 mainly in the form of globulins and albumoses; the most 
 important of them being glutin, which is largely present in 
 wheat-flour. Glutin does not exist as such in wheat-flour, but is 
 formed from the globulin and albumose, naturally present, by the 
 action of water. Glutin being readily digested, forms a very 
 valuable protein food ; it can be obtained also from rye-flour, but 
 less easily than from wheat. Legumin and conglutin are other 
 proteins found chiefly in the Leguminosae, or peas and beans. 
 These proteins are like glutin, derived by the action of water 
 from the globulin and albumose present in the grains. The fats 
 yielded by vegetable food are very small in quantity, and, from a 
 nutritive point of view, quite unimportant. 
 
 The carbohydrates, either as starches, gums (dextrine), or 
 sugars, constitute the chief part of all vegetable foods. In the 
 cereals, potatoes, peas, and beans, starch is the chief carbohydrate, 
 coupled with small quantities of sugars or dextrines. In beetroot 
 and sugar-cane, of course, cane-sugar is the carbohydrate, while 
 in the ripe fruits it exists in the form of glucose or grape-sugar. 
 The starches are a large class, and vary as much in the size, form, 
 and structure of their grains as they do in their origin, which 
 embraces not only wheat, oats, barley, rye, maize, peas, beans, 
 and potatoes, but includes the various forms of arrowroot, tapioca, 
 and sago. In its uncooked state, a starch grain is hard and not 
 easily digested ; it is composed of two bodies called granulose and 
 erythrogranulose, enclosed in cellulose coverings. Granulose, which 
 constitutes the greater part of the starch grain, turns blue with 
 iodine, the erythrogranulose turns red with the same, while the 
 cellulose is turned yellow by iodine. Moist heat causes the 
 cellulose coat to burst, so that the grain swells up and the starch 
 is set free. Starch grains have in the majority of cases a suf- 
 ficiently characteristic appearance, under the microscope, to 
 
174 FOOD. 
 
 indicate their origin, and it is upon their peculiarities of size and 
 form that the various adulterations of the starches by other kinds 
 is best detected. Wheat-flour being the most important, is the 
 kind most usually adulterated with other varieties of starch. To 
 examine a starch under the microscope, it is sufficient to moisten 
 a little of it in a state of fine powder with a drop of water or 
 glycerine upon a glass slide. When so examined, they can be 
 conveniently divided according to their appearance into two 
 groups : (i) a group in which their contour is even; this includes 
 wheat, rye, barley, pea, bean, the arrowroots and potato; (2) the 
 other group is one in which, instead of the contour being even, 
 it is marked by facets or surfaces, either completely, as in oats, 
 maize, and rice, or only partially so, as in tapioca and sago. The 
 chief characteristics and appearance of the various starches will 
 be noted in the subsequent figures. 
 
 The vegetable foods as a class yield excessive quantities 
 of phosphates and potash as compared with the animal foods, 
 which are particularly rich in chlorides and soda; on this 
 account, common salt or chloride of sodium is a special need 
 among vegetable feeders. Iron is usually present in most 
 cereals, particularly in wheat, in which it exists mainly as a 
 phosphate. 
 
 Wheat which is grown in this country is a kind known as 
 Triticum vulgare ; the grain is surrounded by four coats, each of 
 which is composed of special shaped cells. Within these coats 
 is the grain proper containing the starch, fat, proteid, and salts. 
 The starch grains of wheat (Fig. 17) are very unequal in size, 
 some being very large, and others small ; the large ones have a 
 
 central spot, or hilum, and are 
 marked by faintly concentric rings ; 
 the smaller ones are often angu- 
 lar. In the process of milling, the 
 O s — n u 0/ -\ various coats of the wheat grain 
 
 ^C J °C_/ are more or l ess removed and 
 
 separated as bran, the inside of 
 the grain being ground up so as 
 to constitute flour of the best 
 
 Fig. 17.— Wheat starch. 
 
 quality. In the second-rate flours, 
 this separation of the bran is less perfectly carried out, the result 
 being a wholemeal flour of a dark colour. Wheat-flour is rich 
 in protein and carbohydrate, but poor in fat and salts. Its 
 protein, as already explained, exists as a globulin and an albu- 
 mose, and from these, by the action of water, glutin is formed. 
 The amount of glutin obtainable from a flour is a test of its 
 quality and suitability for bread-making ; usually this amount is 
 
WHEAT— BREAD. iy$ 
 
 from 8 to 12 per cent. Its contained water should not exceed 
 1 6 per cent. ; the more water present, the less the keeping quality 
 of the flour; the salts are chiefly phosphates of potash and 
 magnesia. A good flour should be white in colour and free from 
 mouldy smell or acidity. It is occasionally adulterated by mixture 
 with other starches, notably potato and rice starch ; these can be 
 readily recognized with the microscope. Both animal and vege- 
 table parasites occur in flour, and can usually be detected by 
 microscopical examination. The more common animal parasites 
 are the weevil (Cala?idra granaria), the mite (Acarus farinm\ 
 and one or more kinds of moth belonging to the micro-lepidoptera. 
 The commonest vegetable parasites of flour are various fungi ; 
 one called Puccinia graminis, constitutes mildew or red rust of 
 wheat, and whose ripe sporangia show themselves under the 
 microscope as dark-brown club-shaped bodies filled with spores ; 
 another parasite is bunt, caused by the Tilletia caries, which 
 microscopically appears as round reticulated cells. Another 
 fungus, called Ustilago segetwn, causing smut, is more common 
 in barley or oat-flour than in wheat. Its spores or seeds are 
 smaller than those of bunt, being also circular, nucleated, and not 
 reticulated. The chief preparations of flour are bread, biscuits, 
 macaroni, and vermicelli. 
 
 Bread. — The best bread is made from white wheat-flour, but 
 brown and wholemeal breads are made from flours which contain 
 more or less of the bran or wheat-grain coats. The disadvan- 
 tages of wholemeal bread are, first, its dark colour, and next, the 
 irritating and indigestible qualities of the cellulose of the bran. 
 On the other hand, if we take bran as forming 16 parts of the 
 grain, we have an addition to the bread, by inclusion of the 
 bran, of some 07 per cent, of protein and o'i6 per cent, of 
 salts. 
 
 Bread is made by mixing flour with water and kneading it so 
 as to form dough by the cohesion of the glutin. To this dough 
 is added a ferment or leaven, usually consisting of a mixture of 
 potato, flour, and brewer's yeast. The addition of this leaven 
 gives rise to a ferment action on the starch, whereby alcohol and 
 carbon dioxide gas are formed in the dough, resulting in the latter 
 becoming broken up and perforated by innumerable holes. 
 During baking, a certain quantity of sugar and dextrine is formed 
 from the starch, while too, in consequence of the full aeration of 
 the dough, the bread mass becomes light and digestible. In some 
 bakeries, in place of using leaven or yeast, powders consisting of 
 tartaric acid and bicarbonate of soda are added in order to generate 
 the necessary carbon dioxide. In another system the carbon 
 dioxide is generated separately and the gas forced into the dough 
 
176 FOOD. 
 
 by pressure. It is claimed for these unfermented breads that 
 they have the advantage of containing no alcohol, acetic acid, 
 and other bodies, the products of yeast action. This may be the 
 case, but, on the other hand, the action of yeast is largely a 
 digestive one, by which the starch is changed into maltose and 
 dextrine, and some of the proteins into albumoses, or even 
 peptones. 
 
 A good bread should be white in colour; any yellowness is 
 suggestive of either an old flour, bad yeast, or a mixture of rye or 
 bran. The acidity of bread should not exceed 0*18 per cent., and 
 the whole loaf should be permeated in every part with small 
 regular holes. Its contained water should not exceed 50 per cent., 
 nor the ash be over 3 per cent. Alum is occasionally added 
 to bread to improve the colour and check fermentation, any 
 excess over 10 grs. per 4-lb. loaf being regarded as an adultera- 
 tion. It is roughly detected by pouring upon a slice of bread 
 some freshly made decoction of logwood chips and then a solution 
 of carbonate of ammonia. If pure, the bread is only stained pink ; 
 if alum be present, a marked blue to violet colour is produced. 
 The estimation of the precise amount of alum in bread involves a 
 somewhat lengthy process which is beyond the scope of this book. 
 Although bread differs somewhat in composition from flour, its 
 disadvantages as a food are more or less the same, namely, too 
 little fat and too little sodium chloride or salt. In daily life, the 
 deficiency of fat is made up by eating butter, dripping, or bacon 
 with bread, w r hile in the baking half an ounce of salt is added for 
 each 4 lbs. of dough. 
 
 A variety of fancy and patent breads are in the market. The 
 various kinds of Vienna bread are good examples of the former 
 class. These are made from fine flour, milk being added to the 
 dough, and fermentation secured by compressed yeast. Of the 
 patent breads, most are brown in colour, and are made from flours 
 prepared by patent processes. Hovis bread is a well-known 
 example ; this is made from flour containing considerable amounts 
 of the " germ " of wheat. The germ is a part of the wheat grain 
 rich in fat and protein. In the milling of ordinary flour the germ 
 is discarded as offal. Being made from flour which contains 
 some of the most highly nutritive parts of the wheat, Hovis bread 
 naturally possesses an enhanced nutritive value. Some other 
 breads are malted. In their preparation malt extract, which con- 
 tains the ferment diastase, is added to the dough at any early stage 
 before baking. The diastase converts the starch of the dough into 
 malt sugar and dextrin, or, in other words, more or less digests it.. 
 Such bread tends to keep moist. Bermaline bread, made by Mont- 
 gomerie's process, belongs to this group. The diastatic ferment 
 
BISCUITS— MACARONI AND VERMICELLI. 1 77 
 
 is, of course, killed or rendered inactive during actual baking. A 
 recent agitation for what is called " standard bread " is but an 
 expression or protest against the removal from flours of the germ 
 and other highly nutritive parts of the original or natural flour. 
 To a large extent the demand for a standard bread is misdirected, 
 as there are wide differences in protein content and energy value 
 between different wheats. Thus entire wheat flours, including 
 stone ground and standard flour, when made from weak flours, 
 contain less protein and energy value than " households," which 
 have been made from strong wheat. The practical remedy 
 appears to be to increase the quantity of bread taken rather 
 than to rely upon the substitution of one special form of 
 bread for another, and in the case of children to supplement 
 the presumably low-grade bread by other articles, such as 
 milk. 
 
 Biscuits. — The ordinary kinds are nothing more than well- 
 baked mixtures of flour and water, though the more fancy varieties 
 contain often milk, butter, and eggs. Owing to the absence of 
 yeast in their preparation, biscuits do not contain the products of 
 its action upon the carbohydrates and proteins of flour. Taking 
 weight for weight, biscuits contain more nourishment than bread, 
 but are apt to be indigestible and monotonous if consumed for 
 long. 
 
 Macaroni and Vermicelli. — These are both preparations of 
 flour. They are made chiefly from the flours of the hard wheats 
 of France and Italy, which are particularly rich in glutin. They 
 are very valuable foods, being distinctly of higher nutritive value 
 than bread. 
 
 Barley very closely resembles wheat in its composition, but 
 differs somewhat in the character of its proteins. These do not 
 on the action of water form glutin, but remain in a soluble form 
 as globulin, albumin, and albumose. It is difficult to say how far 
 this affects its nutritive value, but it undoubtedly affects the 
 capability of barley being made into bread, and as such largely 
 used as an article of diet. Its starch grains resemble both in size 
 and appearance those of wheat, but their rings or markings are 
 more distinct. When the whole barley grain is ground, it forms 
 barley -meal ; when deprived of its husk, and roughly ground, it 
 constitutes Scotch, milled, or pot barley. 
 
 Pearl barley is the grain deprived ol the husk, rounded and 
 polished by rubbing. So-called patent barley is merely pearl barley 
 crushed to the state of flour. Barley water is prepared from pearl 
 barley, and forms a slightly nutritive liquid for infants and the 
 sick. Malt is the product yielded when barley has been allowed 
 to germinate, and the germination stopped at a certain point by 
 
178 FOOD. 
 
 exposure to heat on a kiln. As a result of this process, the starch 
 of the grain is largely converted into sugar by the development 
 within the barley grain of a peculiar active nitrogenous ferment 
 called diastase. It is from malt that beer is largely made. There 
 being little or no glutin in barley, it cannot be made into 
 ordinary bread ; when barley bread is made, it is usually from 
 a mixture of barley-meal with wheaten flour. Barley cakes 
 are eaten in some places on the score of economy; but, as 
 compared with those made from wheat, are less palatable and 
 less digestible. 
 
 Rye. — Although little used in this country except for malting, 
 rye in the northern countries of Europe is largely used for making 
 bread. In its percentage composition, rye closely resembles 
 wheat, its proteins forming, on the addition of water, a kind of 
 glutin. Rye bread is dark in colour, somewhat heavy and very 
 acid ; but falling little short of wheaten bread in nutritive value. 
 Rye bread is indigestible and apt to cause diarrhoea. If mixed 
 with two parts of wheat-flour, rye-flour makes an excellent bread. 
 The starch grains of rye are very like those of wheat or barley ; but, 
 however, have usually a hilum which is star-shaped, while some of 
 the grains are very large in size (Fig. 18). The common rye is a 
 
 °/~S <£° ver y narc ty cereal, and is commonly 
 (^y 5^ sown in soils which are too poor to 
 ^ ^_^^ v_-J grow wheat. Rye is subject to a very 
 4 I- (? P ecunar fungus disease, by which the 
 o grain is enlarged and turned black, pro- 
 ducing what is known as ergot of rye. 
 O The cause of the disease is a fungus 
 called the Claviccps purpurea. When 
 
 Fig. 18.— Rye starch. - . j •., •• 1,1 
 
 the ergot gets mixed with healthy rye, it 
 becomes mingled with the bread, and leads to a disease in men 
 called ergotism, the symptoms of which are vomiting, diarrhoea, 
 followed, in severe cases by either loss of sensibility, gangrene, or 
 paralysis. This disease is practically unknown in this country, and 
 much less prevalent now than formerly abroad. On account of 
 the excessive size which ergotized rye grains attain, they can be 
 separated by sifting from the unaffected seed : when the grain has 
 been ground into flour, the ergot may be detected either by the 
 microscope or by making of it a paste with an alkali, and then 
 adding nitric acid to excess ; on neutralizing, if ergot be present, a 
 violet-red colour is produced. 
 
 Oats. — As met with in commerce, oats consist of the seeds 
 of the Avena sativa enclosed in their husks. When deprived of 
 this integument, the grain goes by the name of groats, or grits y 
 used in making porridge ; and these groats, when ground down fine, 
 
OATS —RICE — M AIZE. 
 
 179 
 
 Of all the cereals, 
 
 Oo 
 
 SP 
 
 OQ 
 
 o 
 
 Fig. 19.— Oat starch. 
 
 constitute oatmeal, from which gruel is made, 
 oats rank next to wheat as articles 
 of food, being noticeable for con- 
 taining large amounts of portein 
 and fat — particularly the latter. 
 Oats resemble barley rather than 
 wheat, in that their proteins do not 
 form glutin on the addition of 
 water; on this account oatmeal 
 cannot be vesiculated and made 
 into bread like wheaten flour. It 
 is, however, made into thin cakes by mixing into a paste 
 with water, and then baking on an iron plate. Owing to the 
 large amount of cellulose which they contain, this is apt to 
 irritate the intestines, and more or less interfere with digestion. 
 The grains of oat starch (Fig. 19) are minute and faceted, often 
 tending to collect together into groups or compound grains. In 
 the form of oatmeal, oats can be taken for long periods without 
 distaste, and in this form constitute a material part of the dietary 
 of the Scotch peasantry. 
 
 Rice. — The common rice, or Oryza saliva, is extensively 
 cultivated in India, China, West Indies, Central America, and 
 in some parts of Southern Europe. Its starch grains (Fig. 20) 
 very closely resemble those of 
 oats. Rice is a peculiar grain 
 food, inasmuch as it is remark- 
 ably poor and deficient in pro- 
 teins, fats, and salts. For this 
 reason it needs to be combined 
 with meat, peas, or beans, to 
 supply the protein with fat, and 
 common salt. It is essentially a 
 carbohydrate food, and, if properly 
 and sufficiently cooked, is very 
 digestible. It is best cooked by thoroughly steaming ; if boiled in 
 water, ! it loses some of its already small quantity of protein and saline 
 matter. It cannot be made into bread, but is much used in France 
 for mixing with wheaten flour to make the very white bread which 
 is in request in that country. Among large rice-consumers a 
 diseased condition, known as beri-beri, results from the consumption 
 of an over decorticated rice. This successive removal of the outer 
 coverings of the rice grains removes the vitamine containing cells, 
 and proportionately lessens the nutritive value of the rice. 
 
 Maize. — Though not much used in England, maize, or Indian 
 corn, is an important food in America and in Italy, where it is 
 
 « ^ 
 
 a ^> o 
 
 Fig. 20. — Rice starch. 
 
i8o 
 
 FOOD. 
 
 Fig. 21. — Maize. 
 
 called polenta. In its nutritive value, maize resembles oats, con- 
 taining a large quantity of fat. When made either into cakes or 
 porridge, it affords a valuable food. Maize, being deficient in 
 glutin, does not make good bread • it is, moreover, harsh in flavour. 
 This defect is largely removed by treating it with caustic potash, 
 
 a procedure which is the foundation 
 of the process for making it into 
 the common commercial articles ex- 
 tensively sold under the names of 
 oswego, cornflour, and hominy. If 
 imperfectly cooked, or at all decom- 
 posed, maize may give rise to very 
 disturbing symptoms. The grain, too, 
 is liable to a peculiar disease due to 
 a fungus called Sporisorium maidis, 
 which gives rise to a disease in man 
 known as " pellagra," and closely resembling scurvy. This affection 
 is not uncommon in Lombardy, where much maize is eaten as food. 
 The starch grains of oats, rice, and maize somewhat resemble 
 each other, in being all of them faceted. The maize starch grains 
 (Fig. 21) are much larger than the other two, with a distinct 
 hilum ; oat and rice starch grains are smaller than those of maize, 
 and are usually without a hilum, while both the oat and rice grains 
 have a tendency to collect together into clumps. 
 
 Peas and Beans. — These belong to the leguminous group of 
 seeds, which also includes lentils. They have a high dietetic 
 value, in consequence of the large amount of protein which they 
 
 contain ; this is called iegumin t or 
 vegetable casein, and exists largely 
 in combination with sulphur and 
 phosphorus. Both peas and beans 
 are less digestible than the cereals, 
 and require to be boiled slowly 
 for a long time. Added to rice, 
 foods of this class largely furnish 
 the nitrogenous material in the 
 diets of the natives of Hindustan ; 
 but to those unaccustomed to such, 
 it is doubtful whether leguminous seeds can replace the animal 
 proteins. Their large amount of contained protein adapts them 
 for consumption in association with starchy and fatty articles ; a 
 familiar example in our own country being beans and bacon. 
 Unfortunately they are difficult of digestion. The starch grains 
 of peas and beans (Fig. 22) are characteristic, being oval or 
 kidney-shaped ; they have no clear hilum, but usually a deep 
 
 Fig. 22.— Pea flour. 
 
POTATOES. 
 
 181 
 
 
 central longitudinal cleft, or at times an irregularly shaped depres- 
 sion. The addition of hot water to pea or bean flour causes the 
 emission of the typical beany smell. Closely allied to the fore- 
 going foods are the potato, the various arrowroots, sago, and 
 tapioca. 
 
 Potatoes. — These may be considered as occupying a place 
 next in importance to the seeds of the cereals as articles of 
 vegetable food. The potato, used as food, constitutes the tuber 
 or exuberant growth of a portion of the underground stem of the 
 Solatium tuberosum. The tuber develops into a thick fleshy 
 mass, retaining its buds under the name of " eyes," each of which 
 eyes or buds is capable of independent growth when in a detached 
 or isolated state. In its chemical composition, the potato shows 
 a large proportion of starch with a very small quantity of protein. 
 The juice of the potato is acid, due to the presence of a certain 
 amount of free citric acid with citrates of potassium, sodium, and 
 calcium. In its dietetic value the potato is both a carbohydrate 
 and an antiscorbutic. The starch grains of the potato (Fig. 23) 
 are characterized by being large oyster-shaped granules with well- 
 marked concentric rings, and a clear though small hilum at the 
 narrow end. Potato starch is largely used for adulterating the 
 more expensive farinaceous dietetic preparations ; though cheaper, 
 there is nothing to show that potato starch is less nutritive than 
 other starches. Potatoes require to be cooked before being 
 eaten ; this may be done by either steaming, boiling, baking, or 
 frying. The heat coagulates the albuminous juices, and the 
 absorbed water swells up and 
 distends the starch grains. When 
 these changes are complete, the 
 potato is said to be mealy or 
 floury ; when these changes are 
 only partially completed, and 
 the starch cells imperfectly 
 broken up and separated, the 
 potato remains more or less 
 firm, and is spoken of as being 
 close, waxy, or watery. The 
 potato plant is sometimes affected with a fungus — the Phytophera 
 infesta?is — which causes the disease known as potato murrain. 
 This can be readily detected by the microscope. The disease 
 commences in the leaves of the plant, and thence extends to the 
 stem and on to the tubers. On the surface of the latter, brown 
 spots make their appearance, penetrate the potato, and eventually 
 cause it to rot and decay. 
 
 Arrowroots. — The arrowroots are obtained from various 
 
 Fig. 23. — Potato starch. 
 
182 
 
 FOOD. 
 
 sources. Originally the term arrowroot was applied to the 
 starch from the tuber or rhizome of the Maranta arimdinacece, 
 because that root was supposed to have the power of counter- 
 acting the effects of poisoned arrows. The term is now applied 
 to a great variety of starches, but, strictly speaking, should be 
 limited to those known in commerce as Canna, Curcuma, Maranta, 
 and Tacca arrowroots. The root of the plants are dug up when 
 about a year old, washed, and reduced to a pulp. This is re- 
 peatedly washed, passed through coarse sieves to separate the 
 fibres, and the starch allowed to settle, which again is washed 
 and dried. When finished ready for exportation, arrowroot is a 
 white, tasteless, odourless substance, firm to the feel, and pro- 
 ducing, on pressure, a slight crackling noise. Arrowroot, being 
 a pure starch, has no dietetic value beyond that peculiar to this 
 substance. It is chiefly used as a bland article of food for 
 invalids, or, in an ordinary way, as blancmange, puddings, and 
 biscuits. 
 
 Canna arrowroot is furnished by the Canna edulis, a native of 
 the West Indies. Its starch grains are very like potato, but, on 
 the whole, are larger and flatter with more definite striae, or 
 markings. 
 
 Maranta arrowroot, sometimes spoken of as Bermuda arrow- 
 root (Fig. 24), is derived from the Maranta arundinacece, a plant 
 which grows in Jamaica and Bermuda. Its granules are long and 
 ovoid; the rings, or striae, are well-defined; while the hilum is 
 in some circular, and in others a mere transverse line or slit. 
 
 Curcwna arrowroot is furnished from the Curcuma angusti- 
 fo/ia, a species of turmeric plant. Its starch grains vary much 
 
 in size, being, as a rule, flat and 
 elongated. The striae are not 
 complete circles, and the hila, if 
 present at all, are at the narrow 
 end of the grain. 
 
 Tacca arrowroot is obtained 
 from the Tacca oceanica, growing 
 in Tahiti. Its granules are trun- 
 cated, or wedge-shaped at one end. 
 Their striation is indistinct, with 
 a more or less circular hilum. 
 All these starches of arrowroots readily form clear jellies on cool- 
 ing after being heated with water. The true arrowroots are 
 chiefly adulterated with potato, sago, and tapioca. What is called 
 English arrowroot is merely potato starch. 
 
 Tapioca is a starch (Fig. 25) in the form of small granules, 
 truncated at one end with large bases, indistinctly ringed, and with 
 
 Fig. 24. — Arrowroot starch. 
 
SAGO — LIMES AND LEMONS. 
 
 I8 3 
 
 a more or less star-shaped hilum at the apex. It is prepared from 
 the roots of the Jatropha manihot, or Cassava, growing in the 
 Brazils. 
 
 
 Fig. 25. — Tapioca starch. 
 
 Fig. 26. — Sago starch. 
 
 Sago is another starch (Fig. 26) obtained from the interior of 
 the Sagus farinifera i or sago palm, growing in Sumatra. The 
 starch grains are very similar to those of tapioca, but larger. 
 
 Among the large class of succulent vegetables are such common 
 articles of everyday life as cabbage, carrots, parsnips, turnips, 
 beetroot, lettuce, etc. These can scarcely be regarded as foods, 
 because the greater part of their carbohydrates exists in the indi- 
 gestible form of cellulose, while their contained water amounts to 
 about 90 per cent. Their general percentage composition may be 
 put as — protein, 2 ; fat, 0*5 ; carbohydrate, 7 ; salts, 1 ; water, 89*5. 
 All these vegetable foods are valuable for their antiscorbutic 
 properties and for the salts which they contain, their absence 
 from a diet leads to the production of scurvy. 
 
 The fruits are chiefly esteemed for their' taste, though being, 
 as they are, rich in water, vegetable acids, and salts, they are 
 distinctly of service as preventatives of scurvy. Some fruits, such 
 as grapes, contain sugar ; while others, like dates and bananas, 
 contain not only sugar, but starch. When eaten, fruit should not 
 only be ripe, but quite free from decomposition. Some few, like 
 dates and figs, can be dried, but the softer and more perishable 
 varieties cannot be too fresh when eaten. 
 
 Limes and Lemons. — There is a strong traditional belief in 
 the efficacy of the juices of these fruits as preventatives of scurvy. 
 This is justified so long as it is the juice of the Citrus medica 
 limonum, or sweet lime, which is used. Its value in the navy and 
 mercantile marine was demonstrated overwhelmingly up to about 
 1880. Subsequent to that date many outbreaks of scurvy among 
 crews of ships have occurred notwithstanding the issue to them of 
 lime-juice. The explanation is that, prior to that date, lime-juice 
 had been made exclusively from the Citrus medica limonum, which 
 grows in Italy, Sicily, and other countries in the Mediterranean 
 
1 84 FOOD. 
 
 basin. Subsequently, the bulk of the lime juice issued to crews 
 was made from the Citrus medica acida, or sour lime, from 
 Montserrat in the West Indies. The juice of this variety has 
 very little anti-scorbutic value, or only one-fourth of that of the 
 Mediterranean sweet lime. Hence the occurrence of scurvy 
 among crews in spite of an issue of lime juice, and the necessity 
 to recognize that there is a spurious as well as a genuine variety. 
 In the absence of fresh food, especially fresh meat and vegetables, 
 one fluid ounce of the juice of the sweet lime from the Mediter- 
 ranean is an effective daily issue for the prevention of scurvy. 
 
 Both lemon- and lime-juice contain large quantities of citric 
 acid with some malic acid, protein, and sugar. The citric acid, 
 which is an important constituent, averages from 7 to 8 per cent. 
 Apart from their value as anti-scorbutics, both lime- and lemon- 
 juice furnish agreeable and refreshing beverages ; they allay thirst 
 and sickness, and are of special value, too, as antidotes in 
 poisoning by the alkalies. A good and pure lemon-juice should 
 be clear, with an acid but not bitter taste, and possessed of a 
 distinct aroma of the fruit. Many substitutes for lemon-juice are 
 sold, the chief being a solution of citric acid in water flavoured 
 with essence or oil of lemon. The chief adulterations are 
 watering, and the additions of sulphuric and tartaric acids. The 
 addition of water can be detected by the lowering of the specific 
 gravity below 1030, and the diminution of the acidity below 
 30 grs. of citric acid per ounce. Sulphuric acid is probably the 
 most important adulteration ; it may be detected by filtering, and, 
 after acidulation by hydrochloric acid, treating with chloride of 
 barium, when the insoluble barium sulphate is thrown down, if 
 sulphuric acid be present. 
 
 Preserved Foods.— For the preservation of meat, the chief 
 methods are drying, freezing, salting, the injection of preservative 
 solutions, and the exclusion of air, whether by covering it with 
 an impervious coating or by hermetically sealing in tins. Meat 
 preserved by drying is first cut into thin slices, and then exposed 
 to dry air, or to the smoke from a wood fire. In some countries, 
 exposure to a hot sun is sufficient. The employment of extreme 
 cold by freezing is now a very common mode of preserving meat, 
 especially during importation from America and Australia. Meat 
 can be preserved in ice for a long time, but unless the freezing 
 had been commenced before rigor mortis set in, such preserved 
 meat rapidly decomposes so soon as thawing is allowed. Experi- 
 ence shows that it is better to keep the meat at a temperature just 
 short of freezing— say, 35 F. The excellence of the refrigerated 
 meat now available is evidence of the success of this manner of 
 preserving the flesh of animals. 
 
PRESERVED FOODS. 1 85 
 
 Pickling by means of salting is an old and familiar means of 
 preserving meat. During the process, the water of the meat is 
 abstracted, and the salt acts as a preservative. Closely allied to 
 this method is that of injecting preservative solutions ; such as alum, 
 or even common salt, and also by the application of preservatives 
 to the surface, notably salt, sugar, boracic acid, salicylic acid, and 
 charcoal. The exclusion of air is either secured by coating the 
 meat with paraffin, or simply fat, and even by the simple device 
 of plunging the joint into boiling water, so as to form an im- 
 pervious layer of coagulated albumin on the surface. Probably 
 the most frequent method based on air exclusion is that of 
 hermetically sealing in tin cases. Various devices for securing 
 this have been suggested, the chief being either a complete 
 exclusion of the air by sealing in vacuo, or the exclusion of only 
 a part of the air and removal of the oxygen of the remainder by 
 sodium sulphite. 
 
 The chief objections to all these methods are, first, the danger 
 depending upon possible original defects in the meat, and, 
 secondly, the risks of decomposition and putrefaction if the 
 preservation have been imperfectly carried out. In the case of 
 tinned meats, not infrequently ill effects have followed their con- 
 sumption, even when the original material has been above sus- 
 picion, and no sign of putrefaction has been present in the tin 
 contents ; the only unusual character being the presence of salts 
 of tin, lead, or zinc in the meat and jelly, due possibly to the 
 action of variable organic acids upon the solder or tin. Fortunately 
 such events are rare. In the case of tinned or preserved peas an 
 objectionable practice prevails of adding copper salts to give a 
 green colour to the article. A special Committee appointed under 
 the Sale of Foods and Drugs Act has reported that the use of 
 copper salts in the so-called greening of preserved foods be 
 prohibited. 
 
 As being closely allied to preserved forms of meat, allusion 
 may here be made to the many extracts of meat now in the market. 
 Some of them are pure stimulants, and not foods, while others 
 are both. Among the former are Liebig's Extract, ordinary 
 beef-tea, and the soups. These are not protein foods, for besides 
 gelatine they contain only the merest traces of any other protein ; 
 most of the myosin is coagulated during preparation, and left 
 behind in the solid residue. These extracts are really salty foods, 
 containing the sodium chloride from the blood and muscle liquid, 
 the phosphates and potash from the muscle fibre itself, along with 
 the extractives, such as kreatinin. They are essentially stimu- 
 lants, restoring both mental and bodily activity, but in no sense 
 can be regarded as true nitrogenous foods. On the other hand, 
 
l86 FOOD. 
 
 there are some preparations which, besides being stimulants, are 
 also protein foods. These are made by drying more or less com- 
 pletely, partially digested meat, and then mixing with this glutin, 
 starch, and concentrated milk. To this class belong such prepara- 
 tions, often given to invalids, as Bovril, Beef Peptonoids, Fluid 
 Meat, and others. It is of importance to understand the true 
 value of these preparations, as too often their use is misapplied, 
 owing to a misconception of their real nature. 
 
 The yeast extracts cannot be regarded as substitutes for meat 
 extracts. It is true the yeast extracts are rich in albuminous 
 bodies, but these nitrogen containing substances are nearly all 
 nucleo-proteins, or what are called " purin bases." True meat 
 extract contains creatin and creatinin to the extent of 10 per 
 cent. ; yeast extracts contain practically neither of these sub- 
 stances. Apart from the purin bases of meat extract being much 
 less than those present in yeast extract, there is a wide divergence 
 between the two as to the representative purin bases which they 
 contain ; meat extract is rich in hypoxanthin with a little xanthin, 
 while yeast extract contains chiefly adenin and guanin with very 
 little hypoxanthin. Owing to their richness in these particular 
 purin bases, yeast extracts are most unsuitable for the gouty ; in 
 any case they must be regarded as not the equivalent for true 
 meat extracts. 
 
 The dietetic position of condensed and dried preparations of 
 milk has been considered in the section devoted to that food. 
 
 Food Accessories. — This term has been proposed for the great 
 group of condiments and beverages, because they include food 
 stuffs which, though not absolutely necessary for existence, are 
 still of much importance as aids to digestion and to the relishing 
 of the more ordinary articles of diet. The Germans call them 
 11 means of enjoyment," as distinguished from the true foods or 
 " means of nourishment." They include substances varying from 
 the simplest aromatic principles, such as one smells when meat 
 is cooking, or condiments and spices, to the more complex alco- 
 holic and non-alcoholic drinks which so largely enter into the daily 
 dietaries of both civilized and uncivilized peoples. The general 
 action of the food accessories seems to be to stimulate digestion, 
 either directly by affecting the digestive organs, or indirectly 
 through the central nervous system. The condiments are mainly 
 added to food as flavouring agents ; they include such articles as 
 mustard, pepper, onions, cloves, nutmeg, cinnamon, salt, and 
 vinegar. Excepting the two last, all these owe their value as 
 food accessories to aromatic oils which they contain. These 
 essential oils are all stimulants directly of the muscular move- 
 ments of the digestive organs and of the secretion of their juices ; 
 
VINEGAR. 187 
 
 but if taken in excess, easily induce gastric catarrh and exhaustion 
 of the mucous lining of the stomach. The influence of common 
 salt has already been discussed. 
 
 Vinegar is dilute acetic acid, more or less contaminated with 
 gum, sugar, vegetable matter, etc. The varieties of vinegar met 
 with in the market are wine vinegar, malt vinegar, and wood 
 vinegar. The first two are produced by fermentation of alcohol, 
 the process being one of oxidation from alcohol into aldehyde and 
 then into acetic acid ; the last by the destructive distillation of 
 wood and subsequent separation of the acetic acid. The per- 
 centage of acetic acid ought not to be below 3 per cent., while in 
 the best vinegars it may be as high as 6 per cent. Its specific 
 gravity, if a wine vinegar, varies from 1015 to 1022; if a malt 
 vinegar, from 1016 to 1019: anything below these figures is sug- 
 gestive of dilution with water. The chief adulteration of vinegar 
 is the addition of sulphuric acid in excess of that permitted by 
 law, namely, 1 in 1000. If an excess be suspected, it must be 
 determined by barium chloride. Occasionally, artificial vinegars 
 are sold, being really nothing more than very dilute acetic acid 
 coloured with caramel ; they lack, however, the odour and bouquet 
 of the volatile ethers which are so characteristic of the alcoholic 
 fermentation products. The use of vinegar is not only that of an 
 aid to food relishment, but, like other vegetable acids, helps to 
 maintain the alkalinity of the blood, by conversion of the acetic 
 acid into carbonates within the body. In doses of from half to 
 an ounce daily, vinegar is an antiscorbutic, though inferior to 
 lime- and lemon-juice. It is also an aid to digestion, particularly 
 of some shell-fish, such as oysters and mussels. If taken in excess, 
 especially when adulterated with sulphuric acid, vinegar tends to 
 impair digestion. 
 
 The beverages included among food accessories may be 
 divided into those which contain no alcohol and those which do. 
 The non-alcoholic beverages owe their action as food accessories 
 chiefly to the alkaloids they contain ; the more common of these 
 beverages are tea, coffee, and cocoa ; the two former have as their 
 active principle the alkaloid theine or caffeine, while cocoa 
 contains theobromine. Theine or caffeine is essentially a brain 
 stimulant, exciting it to continued activity. If taken in excess, 
 it produces not only an exhausted and disordered nervous system, 
 but gives rise to acid dyspepsia, and considerable delay in the 
 digestive process. Theobromine, though closely allied in its 
 chemical nature to caffeine, has a slightly different physiological 
 action, exerting its effects rather upon the muscular system, which 
 it stimulates into activity, than upon the nervous system. 
 
 Tea consists of the dried leaves of a shrub called the Camellia 
 
1 88 FOOD. 
 
 thea, which grows in China, India, Ceylon, and Japan. As met 
 with in everyday life, tea-leaves are curled, but they uncurl on 
 being placed in hot water, and when so treated, are found to be 
 ovate in shape, pointed, and with a margin toothed like a saw 
 almost to the stalk. The arrangement of the veins in the tea-leaf 
 is characteristic ; the large veins do not reach to the border of 
 the leaf, but turn in towards the midrib. The size of the leaves 
 varies, and usually with them is some stalk. Practically all tea 
 in the market is grown from the same species of shrub, the various 
 names given as indicating different kinds are only trade names, 
 and do not indicate really different varieties of tea-leaf so much 
 as different qualities dependent upon mixing or blending, and 
 on the age of the leaves, or on the soil on which the plant has 
 been grown. In all cases, the leaf most highly valued is the 
 small top leaf of the twig and the bud. Possibly these small 
 leaves are neither finer in quality nor richer and better in flavour 
 than the leaves next in succession, but being more tender and 
 softer in structure, give better and more flavoured infusions. The 
 various teas known under a variety of trade names are all the 
 same in respect of origin, being picked at the same time from the 
 same shrub. Thus, the bud and top leaf constitute Orange 
 Pekoe, the two or three larger leaves growing on the same twig 
 a little lower down are Suchong, and below that the leaves 
 become Congou. 
 
 The most simple division of teas is into the green and the 
 black ; both are from the same plant, the only difference is their 
 colour. Green tea is now little used, in consequence of the 
 disrepute into which it fell as the result of the artificial colouring 
 it received ; but real green tea owes its colouration to being dried 
 over wood fires when fresh. Black teas owe their colour to the 
 leaves having been allowed to lie in heaps for twelve hours, during 
 which they undergo a process of fermentation, and are afterwards 
 dried slowly over charcoal fires. " Brick tea " is made from the 
 refuse, broken leaves and twigs, moulded into shapes. In select- 
 ing a fine tea, one should not be guided by any trade name, but 
 determine by pouring a little boiling water over the leaves and 
 examining them, whether the leaf was a whole leaf and not a large 
 leaf cut into small pieces. The larger the leaf, the weaker will be 
 the infusion and the less the value. What are called " digestive " 
 teas are varieties in which the tannin of the tea has been so altered 
 by electrical treatment that it does not precipitate gelatin, and 
 interferes but little with the digestion of starch. 
 
 The average percentage composition of tea may be expressed 
 as follows : — 
 
TEA. I89 
 
 Water ........ 8-o 
 
 Theine 26 
 
 Tannin J.4'0 
 
 Oil 0-4 
 
 Extractives 150 
 
 Insoluble organic matter . . . 54*0 
 
 A , f- ( Potash, iron, silica, 
 
 Ash ooj alumina, magnesia. 
 
 Formerly, the chief adulteration of tea was by mixing with 
 it other leaves, such as those of the sloe and willow, which have 
 a superficial resemblance to tea-leaves. At the present time the 
 chief adulteration of tea is the admixture of old and exhausted 
 tea-leaves, while in the inferior kinds there is often clay, lime, or 
 ferruginous sand. The total soluble matters obtainable from tea 
 are a ready and convenient index of its quality : they are 
 estimated by infusing a weighed quantity with an excess of 
 distilled water, and evaporating this down to dryness ; the amount 
 of extract so obtained should be at least 30 per cent. If the 
 sample contain many exhausted leaves, the amount of extract 
 obtained will be, of course, less than this. The ash obtained by 
 burning a given quantity of the tea sample should, in a good 
 specimen, be at least 5 to 6 per cent., and not more than 8 per 
 cent. ; and of this at least 3 per cent, or half should be soluble. 
 The precise estimation of the theine and tannin are matters of 
 some difficulty, but are not certain data upon which to judge the 
 purity of any particular sample. 
 
 The most essential points in making good tea of the finest 
 quality and with the least waste are to have actually boiling water, 
 and tea-leaves so crushed and subdivided that the largest possible 
 surface is rapidly exposed to the boiling water in infusing it. 
 This explains why the best tea-infusion in the world is that made 
 by the Japanese from their carefully prepared " tea-powder," 
 which is made by crushing to a fine powder certain well-selected 
 leaves. The tea bricks of China probably owe their superiority 
 to being well-crushed leaves of good quality. The use of tea- 
 powder obtainable in Europe, is handicapped by its liability 
 to adulteration, its uncertain mixture, and difficulties in its 
 preparation. Possibly these disadvantages may be overcome by 
 a more extended employment of tea tabloids, made by the 
 compression of carefully selected and finely ground teas from 
 Japan, India, and Ceylon. 
 
 The excessive drinking of tea is bad, especially when fasting. 
 Tea is not a food, and should not be taken as such ; but if used 
 in moderation, it undoubtedly serves a useful purpose among our 
 daily wants. It is essentially a stimulant of the brain and nervous 
 system, producing no subsequent depression ; but if taken in 
 
190 FOOD. 
 
 excess induces indigestion, loss of appetite, and constipation : in 
 some persons, these bad effects are produced even when only 
 small quantities are consumed. Indian teas are richer in astrin- 
 gent properties than the China teas, for this reason the latter are 
 less disturbing of digestion. 
 
 Coffee is the seed, or berry, of the Caffea Arabica^ a plant 
 growing in most parts of the tropics, but chiefly in Arabia, 
 Abyssinia, Ceylon, and the West Indies. After the seeds have 
 been roasted to a chocolate brown, they are ground to a powder 
 in a mill, and then used in the form of a decoction or infusion. 
 The percentage composition of unroasted coffee may be expressed 
 as follows : — 
 
 Water H'23 
 
 Nitrogenous matter . , . . 12*07 
 
 Caffeine I '21 
 
 Fat 12*27 
 
 Sugar or dextrin ..... 8*55 
 
 Tannin 3 2 '79 
 
 Cellulose 18-17 
 
 Salts 371 
 
 The chief properties of coffee depend upon an aromatic oil 
 and an alkaloidal body called caffeine. Caffeine itself is a nitro- 
 genous crystalline alkaloid identical with theine ; in the roasting 
 of coffee this body is not destroyed, but dissociated, as it were, 
 from its previously existing combination with tannin. During the 
 same process the sugar and dextrin are changed into caramel, and 
 the gas and water of the berry are driven off. 
 
 The adulterations of coffee are chiefly chicory, but at times 
 dates, beans, maize, and acorns have been added. Chicory is a 
 legal addition to coffee, provided such admixture be stated, no 
 limit being fixed as to their relative proportions; as a rule, it 
 amounts to about 30 per cent. The addition of chicory to coffee 
 is considered by most people to add to its flavour. It is probable 
 that much of the present decadence of coffee drinking is due to 
 the excessive addition of chicory, whereby the resulting infusion 
 is wanting in the desired alkaloid caffeine. To make good coffee 
 the berry must be freshly roasted. Good drinkable coffee requires 
 as much as an ounce of recently roasted and ground coffee to 
 each large cup. The prevalent custom in this country is to use 
 barely an ounce to two pints of water, the resulting infusion being 
 more or less mawkish, tasteless, and wanting in stimulating 
 properties. Chicory itself is the dried and ^powdered root of a 
 plant called the Cichorium intybus. In composition it differs 
 much from coffee, containing no caffeine, less fat, but more sugar. 
 It may be readily distinguished from coffee by the fact that when 
 
COFFEE— COCOA. 191 
 
 thrown into water it rapidly sinks and colours the liquid brown, 
 while coffee floats and does not yield any colour. If adulterations 
 are present in the form of the starch grains from various cereals, 
 both a microscopical examination and the blue reaction with a 
 dilute solution of iodine will betray them. 
 
 A more exact estimation of chicory in mixtures of coffee and 
 chicory can be made by calculating the percentage of extract 
 yielded by the sample after infusion in boiling water. Pure 
 chicory gives a mean percentage extract of 70; while pure coffee 
 gives a remarkably constant percentage extract of 24. 
 
 Coffee, like tea, appears to act decidedly upon the nervous 
 system, which it stimulates, causing wakefulness and increased 
 brain action. In some people it has an aperient action by 
 stimulating the muscular coats of the intestines. 
 
 Cocoa is the roasted seed of the Theobroma cacao, growing 
 chiefly in the West Indies. Cocoa nibs are the seeds or beans 
 roughly broken ; flake cocoa is the same completely ground and 
 crushed ; soluble cocoa is the same freed from cellulose ; while 
 prepared cocoa is the same after half or more of its contained oil 
 or fat has been removed, and in most cases starch and sugar 
 added. The percentage composition of cocoa beans may be said 
 to be as follows : — 
 
 Water , 6'0 
 
 Theobromine 1 5 
 
 Fat 50'o 
 
 Starch , . icro 
 
 Salts 3-6 
 
 Gum ....... o , 8*o 
 
 Cellulose 20*9 
 
 Theobromine closely resembles caffeine, not only in its nature, 
 but in its action. The adulteration of cocoa is chiefly in the 
 direction of the addition of sugar and starch, which the microscope 
 will detect ; while, by some, the removal of the fat, so as to reduce 
 it below 20 per cent, is regarded as an adulteration. Apart from 
 cocoa by nature containing nitrogenous and fatty matter, in its 
 commercial forms it contains so much starch and sugar that it is 
 rightly regarded to some extent not only as a protein and fatty 
 food, but also a carbohydrate one. Cocoa differs much from 
 both tea and coffee in having but little stimulant action, but it 
 does possess some nutritive value, and, as such, may in a limited 
 sense be regarded as a food. 
 
 Chocolate is a preparation of cocoa, from which the greater 
 part of the fat has been removed, and which, after being mixed 
 with sugar and various flavouring substances, is made into a paste 
 with water, and then pressed in moulds. 
 
192 FOOD. 
 
 Aerated Waters. — In addition to the large number of natural 
 waters, rich in carbon dioxide, there are many artificial aerated 
 waters which have come into general use of late years. The 
 peculiar feature of them all is that they are prepared by forcing 
 carbon dioxide into ordinary water, and adding to it either some 
 saline or a flavouring agent. Much of what is known and largely 
 sold as " soda water" really contains no soda at all, but is merely 
 an ordinary water highly aerated and charged with carbon dioxide. 
 If the gas, naturally present in the water, is not previously 
 thoroughly expelled, the carbon dioxide is imperfectly dissolved, and 
 when the bottle is opened, tends to froth and escape violently. 
 The chief sources of danger in these beverages lie in the possible 
 employment of originally impure water; the making of the car- 
 bon dioxide from impure materials ; the presence of either lead, 
 copper, or tin, as the result of imperfect washing of the gas, or 
 derived from the plant used in the manufacture. These dangers 
 can only be obviated by the exercise of care in the selection of 
 the water and materials used. Fortunately carbon dioxide, under 
 pressure, is antagonistic to the majority of micro-organisms 
 present in water. This is a fact which may in great measure explain 
 the remarkable immunity from filth diseases, such as enteric fever 
 and cholera, which attends the habitual use of highly aerated 
 waters in place of the ordinary supplies. It would, however, be 
 desirable if legislation could make it illegal to use any water but 
 that possessing all the qualities of an unobjectionable drinking 
 water for the making of aerated beverages. The presence of any 
 deleterious metals is uncommon in these drinks, except those 
 made in inferior and faulty machines. The aerated waters stored 
 in bottles with patent stoppers of porcelain, glass, and vulcanite 
 are, of course, the most generally free from any of the hurtful 
 metals. It is questionable whether any real danger exists to 
 health under this heading. 
 
 Alcoholic Beverag'es. — Among the alcoholic beverages, the 
 chief are beer, wine, and spirits ; these all owe their action as 
 food accessories partly to the alcohol and partly to certain 
 aromatic principles and substances which they contain. The 
 alcoholic beverages are sometimes called fermented liquors, 
 because the alcohol contained in them is the result of a process 
 called fermentation set up in either the natural sugars which we 
 extract from fruits, stalks, or roots of certain plants, such as the 
 grape, the sugar-cane, and the beetroot, or in the secondary sugars 
 which we prepare by art from potatoes, cereal grains, malt, and 
 the starches generally. 
 
 If we take a natural sugar, such as grape-sugar present in the 
 fruit of the vine, dissolve it in water, and add a little yeast to it, 
 

 ALCOHOLIC BEVERAG1 [93 
 
 the solution quickly begins to ferment. During this fermentation 
 
 the sugar is split up into alcohol and carbon dioxide. The former 
 remains in the liquid, while the carbon dioxide escapes as a gas in 
 bubbles into the air. The yeast which brings about this remark- 
 able change is in reality a microscopical plant, made up of oval 
 cells about ^y~ of an inch in diameter, filled with granulai 
 matter. The scientific name for yeast is Torula ccrcvisicz. It is 
 by virtue of this fermentation of grape juice, as we shall learn 
 later, that wine and brandy are made. If instead of grape-sugar, 
 we take common cane-sugar, dissolve it in water, and mix with 
 yeast, fermentation is set up in a similar way; excepting that the 
 cane-sugar is first changed into fruit or grape-sugar by the action 
 of the yeast, and then the grape-sugar is split up into alcohol 
 and carbon dioxide. These changes go on whether the sugar be 
 exposed to the air or not. If now, instead of taking eitlx 1 grape- 
 sugar or cane-sugar, we take some ordinary starch, boil it in a 
 dilute solution of almost any acid, particularly 1 per cent, of 
 sulphuric acid, the starch is converted into a sweet gum-like 
 body called dextrin, and subsequently into a kind of sugar call' d 
 maltose, which closely resembles in sweetness, chemical composi- 
 tion, and general properties that of the grape. If yeast be now 
 added to this altered starch, the same fermentation and production 
 of alcohol takes place. It is from potato starch treated in this 
 manner that large quantities of spirit, known as potato brandy, 
 are manufactured in various countries. 
 
 In a previous chapter it has been explained that the cereal grains 
 consist essentially of two principal substances — namely, starch 
 and a nitrogenous body of the nature of a globulin or albumose. 
 These evidently are intended by nature to afford the first food of 
 the young plant as it grows from the grain; but in their natural 
 state these are insufficiently soluble to supply the wants of the 
 growing germ. Under the influence of moisture, as when a grain 
 of wheat sprouts, a ferment in the form of a soluble white sub- 
 stance called diastase is formed in the grain, which so converts 
 the nitrogenous elements of the seed as to make it usable by the 
 young plant, and for the same purpose also changes the insoluble- 
 starch into soluble starch, dextrin, maltose, and glucose or grape- 
 sugar. This is why sprouted corn always has a swe< t taste. The- 
 maltster, brewer, and distiller avail th< mselves of this natural 
 change in the constituents of sprouting grain, and on a large scale 
 call into action the chemical influence of this unorganized ferment 
 known as diastase. 
 
 In the manufacture of all fermented drinks, therefore, two 
 distinct chemical processes are involved ; there is first the ( hange 
 of the starch into sugar, and secondly the change of the sugar 
 
 11 
 
194 FOOD. 
 
 into alcohol and carbon dioxide. This latter we know is brought 
 about by fermentation through the medium of yeast, while the 
 former may be secured by the artificial conversion, by means 
 of sulphuric or other acid, of potato or other starch into sugar ; 
 or the grain may be manufactured into malt and the remarkable 
 influence of diastase called into play. 
 
 The essential element in all fermented drinks, no matter how 
 made, is alcohol, which is a neutral compound of oxygen, carbon, 
 and hydrogen, having the chemical formula of C 2 H 6 0. When 
 quite pure and free from water, alcohol is termed absolute alcohol^ 
 having a specific gravity at 6o° F. of 079381 ; when mixed with 
 16 per cent, of water, it is called rectified spirit ', and when mixed 
 with 56*8 per cent., volume in volume of water, it constitutes 
 proof spirit. Proof spirit is a term constantly in use for excise 
 purposes, signifying a dilute spirit of definite strength. If 
 expressed as volume in volume, proof spirit contains 56*8 per 
 cent, of absolute alcohol ; if as weight in weight, 49*25 per cent. ; 
 if as weight in volume, 45*4 per cent. ; the remainder in each 
 case being distilled water. The ratio of alcohol to proof spirit 
 in each of these cases being for volume in volume as 1 is to 
 1*76; for weight in weight as 1 is to 2*03, and for weight in 
 volume as 1 is to 2*21. We can, therefore, if in any case the 
 percentage of contained alcohol be known, calculate the amount 
 of proof spirit present by multiplying the given percentage of 
 alcohol by any of the foregoing ratios. 
 
 Spirits which are weaker than proof are described as being 
 
 under proof ; when stronger than proof as being over proof. 
 
 Thus, say a sample of whisky is found to contain 70 per cent., 
 
 volume in volume, of alcohol; then 70 X 176 = 123*2, and the 
 
 excess of this product over 100 or 23*2 gives the number of 
 
 degrees over proof which the sample has. If, on the other hand, 
 
 it contain but 24 per cent, of alcohol, volume in volume, then 
 
 24 X 176 = 42*24, and by just so much as this figure is greater 
 
 or less than 100 is the sample degrees over or under proof, that 
 
 being, in this case, just 5776 under proof. Conversely, if the 
 
 degree of strength of any spirit over or under proof be known, 
 
 the percentage of alcohol present can be calculated either as 
 
 volume in volume, weight in weight, or weight in volume. Thus, 
 
 too + x 
 say a sample of brandy be x degrees over proof; then 7-7— 
 
 gives the percentage, volume in volume, of alcohol which it 
 
 -rr • 1 1 1 r i IO ° ~~ X • 
 
 contains. If it be x degrees under proof, then — , gives the 
 
 percentage, volume in volume, again of alcohol. 
 
 Nutritive Use of Alcohol. — The use of alcohol by man is of 
 
NUTRITIVE USE OF ALCOHOL. 195 
 
 very ancient origin, and owing to the ease with which alcohol 
 is produced by fermentation from sugars and starches, its early 
 discovery and almost universal use throughout the world are not 
 at all remarkable. In attempting to understand the physio- 
 logical action of alcohol, one must bear in mind that there is a 
 distinction between the effects of alcohol taken in dietetic doses 
 and when taken in excess, and too, that the physiological action 
 of pure alcohol is not quite the same as that of many alcoholic 
 beverages, because many of these contain other bodies besides 
 alcohol, and which have a distinct action of their own. More- 
 over, it must not be forgotten that what is a dietetic dose for one 
 person is an excess for another. As based upon the experiments 
 of Parkes, Anstie, and others, the amount of alcohol which can 
 be taken daily by the average individual without doing harm is 
 between one and two fluid ounces. This is contained in about 
 two ounces of ordinary spirit, such as brandy or whisky, and 
 in half a pint of the light wines, such as clarets and Bur- 
 gundies, or in about a pint and a half of the ordinary beers 
 and ales. 
 
 It is still a matter of dispute as to how alcohol is eliminated 
 from the body, and whether any of it is destroyed in the tissues. 
 The probable truth is that alcohol is oxidized in the body, the 
 products being excreted in the urine. In small doses, alcohol 
 stimulates the nervous system, reddens the lining membrane of 
 the stomach, increasing the secretion of the gastric juice, and 
 thus may in very small doses promote the appetite. When 
 carried into the circulation, it increases the heart's action, and 
 at the same time causes the smaller blood-vessels or capillaries 
 to dilate. It is an unsettled question as to how far alcohol 
 lowers the body temperature in health, but it is beyond question 
 that it tends to lower the natural resisting power of the body 
 against cold, and is in consequence unsuited for those exposed 
 to great degrees of cold as in the Arctic regions. If taken too 
 often, even in small doses, or taken in any large quantity at one 
 time, alcohol instead of stimulating the nervous system actually 
 depresses and paralyzes it, as evidenced by intoxication. In 
 these circumstances the perception power of the brain is depressed 
 or paralyzed, correct judgment is impossible, while speech is 
 disordered and the emotions out of all control. If repeatedly 
 taken to excess, alcohol delays digestion, causes catarrh of the 
 stomach and bowels, accompanied by such degenerated con- 
 ditions of both the liver and kidneys as to result in death. It is 
 beyond question that, when taken in sufficient quantities to pro- 
 duce these effects upon the brain and nervous system, alcohol 
 causes an immensity of harm ; the physical, moral, and social 
 
I96 FOOD. 
 
 evils of intemperance are only too familiar to us all. But how far 
 alcohol is beneficial or not when taken in small or dietetic doses 
 is still a matter of controversy between the teetotalers and those 
 who advocate moderation. 
 
 The evidence is overwhelming that in respect of physical 
 effort a person can do quite as hard if not harder work without 
 alcohol than with it ; the experience of wars and expeditions in 
 all climates, where abstinence was either enforced by order or by 
 circumstances, shows that soldiers endure more fatigue, are 
 healthier, and fight better without alcoholic stimulants than with 
 them. On the other hand, it must be borne in mind that in 
 ordinary life to many the cares and worries of business and 
 existence are such that to them, after the labours of the day, a 
 moderate amount of alcohol in some form or other is not only 
 an advantage but almost a necessity. To the old and feeble, the 
 use of alcohol is not less valuable. In all cases, however, it 
 should be remembered that alcohol should never be taken during 
 working hours with the idea that the body and brain are likely to 
 do more work after it than before ; the only time when it can be 
 advantageously used is after the day's work is done • so taken, its 
 influence is often to check tissue change and waste, to soothe 
 and stimulate an exhausted brain with a removal of the sense of 
 fatigue, and to promote digestion. Alcohol should never be taken 
 fasting ; its best effects are secured when taken with food, and at 
 no meal more so than at the late dinner or supper. 
 
 The essential facts to be borne in mind are that the main 
 action of alcohol is confined to the nervous system, and that its 
 action is narcotic and not stimulant. True as this is, it must be 
 admitted that there is nothing intrinsically bad about a narcotic 
 and nothing intrinsically good about a stimulant. Each has its 
 proper utility under given conditions. Alcohol has an undoubted 
 food value from the point of view of its capacity to act as a fuel in 
 the body, but at the same time it is a tissue poison, and for that 
 reason its utility is merely that of a sedative or narcotic drug, to 
 be used or taken only at long intervals. Its food value is suit- 
 able only in disease, exhaustion, and similar emergencies. As 
 an aid to work, alcohol is physiologically unsound. On the 
 other hand, the temperate consumption of alcoholic liquors may 
 be considered physiologically harmless in the case of the majority 
 of normal adults. It is, however, definitely injurious for children, 
 for persons of nervous instability, and for those who have had 
 severe head injuries or nervous shock. 
 
 Beer. — The usual definition of beer is, that it is a fer- 
 mented infusion of malt flavoured with hops. This, however, is 
 not quite correct at the present day, as sugar largely takes. 
 
BEER. 
 
 197 
 
 the place of malt, and other vegetable bitters that of hops; so 
 that probably a more accurate definition would be, to call it 
 a fermented saccharine infusion to which has been added any 
 wholesome bitter. Formerly the substitution of quassia, gentian, 
 calumba, or any other bitter in place of hops was illegal, but 
 now it is not the case, with the result that all kinds of bitters 
 may be used provided they are wholesome. As a matter of fact, 
 however, in the best beers even now, the only bitter used is 
 hops. 
 
 Modern beers may be divided into two great groups, namely, 
 the non-malt beers and the malt beers. What are called non- 
 malt beers are those made by a yeast fermentation of an infusion 
 of sugar, mainly derived from starch chemically or artificially con- 
 verted, as by the action of sulphuric acid. Malt beers are the 
 result of a similar yeast fermentation of an infusion of sugar, only 
 in this case the sugar is derived from the natural conversion of 
 grain starch by means of germination or malting. In both 
 instances, the resultant liquor is an alcoholic one, in which a 
 portion of the alcohol becomes transformed into aldehyd, and 
 subsequently by a further oxidation changed into acetic acid. 
 The essential points in brewing are the facts that the quantity of 
 yeast to be added and the temperature at which fermentation is 
 allowed to take place, vary with different kinds of beer ; also that 
 yeast works better when transferred from one kind of beer to 
 another; and that the fermentation must be so regulated that the 
 whole of the sugar contained in the wort is not transformed into 
 alcohol, as if it is all so transformed the beer has no keeping 
 power — that is, it would turn sour in the casks. This turning 
 sour is due mainly to the passage of the alcohol into aldehyd and 
 the subsequent oxidation of this into acetic acid. 
 
 There are many varieties of ales and beers, the chief being : 
 Pale and Mild Ales, made from the finest dried malt and the best 
 hops; the mild ale is usually sweeter, stronger, and less bitter 
 than the pale. Porter is nothing more than a weak mild ale, 
 coloured and flavoured with roasted malt. Stout is a richer and 
 stronger kind of porter. The German Beers are fermented by 
 means of sedimentary yeast as distinguished from the surface 
 yeast used in England. Their fermentation is carried on at a 
 lower temperature than in the case of British beers. They con- 
 tain also less alcohol than the English, but are richer in carbon 
 dioxide, and keep better. Lager and Bock beer is made from 
 a stronger wort, and is proportionately richer in alcohol and malt 
 extract. The Belgian beers are made with unmalted wheat and 
 barley ; they take long periods to ferment, doing so spontane- 
 ously, no yeast being added ; as a rule, they are hard from the 
 
I98 FOOD. 
 
 presence of much acid. Bottled beers are all bottled while 
 fermentation is going on, and owe their sparkling and frothing to 
 the excess of carbon dioxide in them. 
 
 The chief constituents of ales, stouts, and porters are — alcohol, 
 dextrin, sugar, hop resin or oil, glutin, acetic and lactic acids, 
 carbon dioxide, mineral ash, and water. The alcohol in beer, 
 varies from 1 to 10 per cent, in volume. The free acidity which 
 arises chiefly from acetic, lactic, and malic acids, if expressed as 
 acetic acid, ranges from 15 to 40 grs. per pint. The malt extract, 
 which consists mainly of sugar, dextrin, and cellulose, varies from 
 4 to 15 per cent. Some beers have been known to be the cause 
 of arsenical poisoning, as in the notorious epidemic in Lancashire 
 in 1900. This arose from the employment of an arsenically 
 tainted sulphuric acid for Che manufacture of the sugar sub- 
 sequently used for brewing the beer. Such a sequence of events 
 is fortunately rare, but it brings into prominence the great need 
 for scrupulous purity in all ingredients used in the preparation of 
 foods and drinks. 
 
 Regarded as a food, the nutritive value 01 beer is small, 
 though, of course, higher than other alcoholic drinks, owing to 
 the large amount of maltose, dextrin, and other saccharine 
 substances which it contains in the form of malt extract. In the 
 main, its dietetic effects are those of alcohol, modified by the 
 associated action of other ingredients. Beer appears to have 
 some action peculiarly its own; this is generally attributed to 
 hipulin, which is the active principle in hops. On some people, 
 beer acts as a depressant, and, if taken in excess, it undoubtedly 
 is a soporific or stupor producer. Beer also seems to exercise 
 slight but continuous interference with tissue change, with a 
 tendency to fatten and produce gout and rheumatism. When 
 drunk to any excess, beer appears to have a retarding effect upon 
 digestion. 
 
 In its general characters a good beer should be transparent 
 with a red-brown colour, and possessed of a semi-vinous flavour. 
 Formerly, many hurtful ingredients were added to beer as adul- 
 terants, but in the present day, practically the only adulterations 
 are water with occasionally salt or alum. Salt is usually present 
 in small amounts in the best beers, being derived from the water 
 and other ingredients in making ; but if present in excess of 
 10 grs. per gallon amounts to an adulteration. Alum is some- 
 times added to beer combined with salt, and sulphate of iron or 
 even sugar in order to raise the density and give a "head" 
 after dilution with water. Such beer soon undergoes secondary 
 fermentation, and becomes sour, heady, and unwholesome. The 
 quality of ale is most conveniently estimated by a determination 
 
BEER. 
 
 199 
 
 of the amounts of its acidity and its contained alcohol. For 
 determining the acidity of beer, we need an alkaline solution 
 of known strength, of which 1 c.c. is equal to 6 mgms. of acetic 
 acid. The amount of this solution required to exactly neutralize 
 a given quantity of beer is determined and expressed as acid in 
 grains per pint. This, representing the total acidity of the beer, 
 rarely exceeds 26 grs. per pint, more commonly is about 16 grs. 
 per pint 
 
 To determine the amount of contained alcohol and the original 
 gravity of a beer, the following procedure is necessary : By means 
 of a gravity bottle determine the specific gravity of the sample at 
 6o° F. Next evaporate 200 c.c. of the beer down to about one- 
 third, allow to cool, measure, and re-make up to its original volume 
 with distilled water, and then determine the specific gravity of this 
 de-alcoholized beer at 6o° F. Deduct the gravity obtained before 
 evaporation from that after it, and take the difference from 1000. 
 Having obtained this figure, refer to the accompanying table of 
 degrees of specific gravities, and read off opposite the number 
 obtained the percentage of alcohol present. 
 
 Specific 
 
 Volumes 
 
 Specific 
 
 Volumes 
 
 Specific 
 
 Volumes 
 
 gravity 
 
 per cent, of 
 
 gravity 
 
 per cent, of 
 
 gravity 
 
 per cent, of 
 
 at 6o° F. 
 
 alcohol. 
 
 at 6o° F. 
 
 alcohol. 
 
 at 6o° F. 
 
 alcohol. 
 
 IOOO'O 
 
 O'OO 
 
 990'2 
 
 7*oo 
 
 979*0 
 
 I7*00 
 
 999*9 
 
 005 
 
 989-0 
 
 8*oo 
 
 978-0 
 
 18*00 
 
 999-8 
 
 015 
 
 987-8 
 
 9*00 
 
 9770 
 
 I9*00 
 
 999-1 
 
 0-55 
 
 986-6 
 
 io*oo 
 
 976*0 
 
 20 'OO 
 
 998'S 
 
 I'OO 
 
 985-4 
 
 1 1 00 
 
 970*9 
 
 25*00 
 
 997-o 
 
 2'00 
 
 984-3 
 
 12-00 
 
 965-4 
 
 30-00 
 
 995-6 
 
 3-00 
 
 983-2 
 
 1300 
 
 959'2 
 
 35'oo 
 
 994-2 
 
 4 # oo 
 
 982*1 
 
 14-00 
 
 951*9 
 
 40 00 
 
 9929 
 
 5-00 
 
 98l*I 
 
 15-00 
 
 
 
 99i'5 
 
 600 
 
 980*0 
 
 1 6 '00 
 
 
 
 From the same data, practically, the gravity of the original 
 wort from which the beer was brewed can be calculated. Taking 
 the difference between the two gravities, obtained respectively 
 before and after de-alcoholization, we obtain a figure or number 
 which is called the approximate spirit indication. Next determine 
 the acidity of the beer as a percentage of acetic acid : from the 
 following acidity table, read off the spirit indication corresponding 
 to this acidity. Add this figure to that of the approximate spirit 
 indication, and we get what is called the true spirit indication. 
 
200 
 
 FOOD. 
 
 Table for ascertaining the Spirit Value of Active Acid in Beer. 
 
 Per- 
 
 
 
 Corresponding degre< 
 
 :s of spirit indication. 
 
 
 
 centage 
 
 
 
 
 
 
 of acetic 
 
 
 
 
 
 
 
 
 
 
 
 acid. 
 
 o"oo 
 
 O'OI 
 
 0'02 
 
 0*03 
 
 0*04 
 
 0*05 
 
 o'o6 
 
 0*07 
 
 o'o8 
 
 009 
 
 O'O 
 
 
 0-02 
 
 0'04 
 
 o'o6 
 
 0*07 
 
 0-08 
 
 CO9 
 
 Oil 
 
 0'12 
 
 0*13 
 
 O'l 
 
 0*14 
 
 0'15 
 
 0-I7 
 
 0-18 
 
 0*19 
 
 0'2I 
 
 0"22 
 
 0-23 
 
 0*24 
 
 0'26 
 
 0*2 
 
 0*27 
 
 0-28 
 
 0-29 
 
 0-31 
 
 0-32 
 
 o'33 
 
 0-34 
 
 035 
 
 0-37 
 
 C38 
 
 0-3 
 
 0-39 
 
 0*40 
 
 0'42 
 
 o*43 
 
 0-44 
 
 0*46 
 
 0-47 
 
 0-48 
 
 0-49 
 
 0'5I 
 
 o- 4 
 
 0-52 
 
 0'53 
 
 - 55 
 
 0-56 
 
 o'57 
 
 o'59 
 
 o*6o 
 
 o - 6i 
 
 0*62 
 
 064 
 
 o'5 
 
 0-65 
 
 o-66 
 
 067 
 
 0*69 
 
 070 
 
 071 
 
 072 
 
 o73 
 
 075 
 
 O76 
 
 06 
 
 077 
 
 078 
 
 o-8o 
 
 o-8i 
 
 0-82 
 
 0-84 
 
 0-85 
 
 o-S6 
 
 087 
 
 089 
 
 From the annexed table (pp. 201 and 202) read off the 
 gravity (representing sugary extract which has fermented or 
 become converted into alcohol and acid) corresponding to this 
 spirit indication. If this figure be now added to the gravity given 
 by the de-alcoholized beer (representing unfermented sugary 
 extract), we get then the probable original gravity of the wort 
 from which the beer was brewed. 
 
 Example. — Say a beer sample has yielded 0*04 per cent, of acetic acid, 
 and that the first and second gravities were respectively 1016-47 and 1023-36 ; 
 the difference between these gravities is clearly 689, and this taken from 1000 
 gives 993'H corresponding in the alcohol table to 4-84 per cent, of contained 
 alcohol. The original gravity of the wort would be calculated as follows : 
 The difference between the two gravities taken before and after de-alcoholiza- 
 tion we know to be 6*89, while the percentage of acetic acid is 0*04, corre- 
 sponding by the acidity table to a spirit indication of 0*07. Then 6-89 
 plus 0*07 gives a true spirit indication of 6*96, which, by a reference to 
 the other table, is equivalent to 28 6 degrees of gravity lost by fermentation. 
 Then, as the second gravity, or that obtained after de-alcoholization and 
 representing unfermented extract, is 1023*36, by adding this to 28-6 we get 
 1051-96 as the probable original gravity of the wort from which the actual beer 
 sample was brewed. 
 
 Some idea as to the solids or amount of extract per cent, in 
 a beer can be obtained if, after taking the specific gravity after 
 de-alcoholization, the excess of gravity over 1000 be divided by 
 4 ; this gives an approximate conclusion as to the body of the 
 beer ; the more extract, the greater is the body of the ale. In 
 the example given above, the extract would be calculated as being 
 23*36 divided by 4 or 575 per cent. 
 
 Wine. — The term wine is held to mean " the fermented juice 
 of the grape with such additions only as are essential to the 
 stability or keeping quality of the wine." This definition admits 
 as wines those beverages which, made from grape juice, require 
 to preserve them the addition of spirit, as in the case with some 
 
DEGREES OF SPIRIT INDICATION. 
 
 20 1 
 
 Table showing Degrees of Spirit Indication with corresponding 
 
 Degrees of Gravity lost. 
 
 Spirit in- 
 dication. 
 
 Hundredths of a degree. 
 
 Degrees 
 
 
 
 
 
 
 
 
 
 
 
 and 
 
 o'oo 
 
 O'OI 
 
 0'02 
 
 0-03 
 
 0*04 
 
 0*05 
 
 o'o6 
 
 0*07 
 
 0*08 
 
 0*09 
 
 tenths. 
 
 
 
 
 
 
 
 
 
 
 
 4 -0 
 
 15-10 
 
 I5'I4 
 
 I5-I8 
 
 15-22 
 
 15-26 
 
 15-30 
 
 J 5-34 
 
 15-38 
 
 15-42 
 
 15-46 
 
 •I 
 
 i5'5o 
 
 15*55 
 
 I5-60 
 
 15-65 
 
 15-70 
 
 15-75 
 
 15*80 
 
 15-85 
 
 15*90 
 
 I5'95 
 
 *2 
 
 16*00 
 
 1 6 "04 
 
 16-08 
 
 l6'I2 
 
 16-16 
 
 16*20 
 
 16-24 
 
 16*28 
 
 16*32 
 
 l6* 3 6 
 
 *3 
 
 16*40 
 
 16-44 
 
 16-48 
 
 16-52 
 
 16-56 
 
 16*60 
 
 16*64 
 
 16-68 
 
 16*72 
 
 l6* 7 6 
 
 '4 
 
 1 6 -So 
 
 16-85 
 
 16-90 
 
 16*95 
 
 17*00 
 
 17-05 
 
 17*10 
 
 I7-I5 
 
 I7*20 
 
 17-25 
 
 5 
 
 17-30 
 
 I7'34 
 
 I7-38 
 
 17-42 
 
 17*46 
 
 17-50 
 
 I7-54 
 
 I7-58 
 
 I7'62 
 
 17*66 
 
 •6 
 
 17-70 
 
 17*75 
 
 17-80 
 
 17*85 
 
 17*90 
 
 I7'95 
 
 18*00 
 
 18*05 
 
 18*10 
 
 l8*I5 
 
 7 
 
 l8*20 
 
 18-24 
 
 18-28 
 
 18-32 
 
 18*36 
 
 18*40 
 
 18*44 
 
 18*48 
 
 18*52 
 
 18*56 
 
 •8 
 
 18-60 
 
 18-65 
 
 18-70 
 
 18-75 
 
 1 8- 80 
 
 18*85 
 
 1890 
 
 18-95 
 
 19*00 
 
 19-05 
 
 '9 
 
 19-10 
 
 19-14 
 
 19-18 
 
 19-22 
 
 19*26 
 
 19-30 
 
 19-34 
 
 I9-38 
 
 19-42 
 
 19-46 
 
 5'0 
 
 19-50 
 
 19-54 
 
 I9-58 
 
 19*62 
 
 19-66 
 
 19*70 
 
 19-74 
 
 19-78 
 
 19*82 
 
 19*86 
 
 •1 
 
 19-90 
 
 1995 
 
 20-00 
 
 20*05 
 
 20- 10 
 
 20*15 
 
 20*20 
 
 20*25 
 
 20*30 
 
 20-35 
 
 •2 
 
 20*40 
 
 20-45 
 
 20-50 
 
 20*55 
 
 20'60 
 
 20*65 
 
 20*70 
 
 2075 
 
 20*80 
 
 20-8 5 
 
 "3 
 
 20-90 
 
 20-94 
 
 20-98 
 
 21*02 
 
 21 -06 
 
 21*10 
 
 21*14 
 
 2I*l8 
 
 21*22 
 
 21*26 
 
 '4 
 
 21-30 
 
 21-35 
 
 21*40 
 
 2 1 '45 
 
 21-50 
 
 2i'55 
 
 21*60 
 
 21*65 
 
 2I*70 
 
 2i*75 
 
 '5 
 
 21 'SO 
 
 21*84 
 
 21-88 
 
 21*92 
 
 21-96 
 
 22*00 
 
 22*04 
 
 22*o8 
 
 22*12 
 
 22'l6 
 
 •6 
 
 22'20 
 
 22-25 
 
 22-30 
 
 22-35 
 
 22-40 
 
 22-45 
 
 22*50 
 
 22'55 
 
 22*6o 
 
 22*65 
 
 7 
 
 22-70 
 
 22-74 
 
 22-78 
 
 22-82 
 
 22-86 
 
 22*90 
 
 22*94 
 
 22*98 
 
 23-02 
 
 23*06 
 
 •8 
 
 23-IO 
 
 23-15 
 
 23-20 
 
 23-25 
 
 23-30 
 
 23-35 
 
 23-40 
 
 23-45 
 
 23-50 
 
 23'55 
 
 '9 
 
 23*60 
 
 23-65 
 
 23-70 
 
 23-75 
 
 23-80 
 
 23-85 
 
 23-90 
 
 23-95 
 
 24*00 
 
 24-05 
 
 6*o 
 
 24-IO 
 
 24-15 
 
 24-20 
 
 24-25 
 
 24-30 
 
 24-35 
 
 24*40 
 
 24-45 
 
 24-50 
 
 24-55 
 
 •1 
 
 24*60 
 
 24-65 
 
 24-68 
 
 24-72 
 
 24-76 
 
 24*80 
 
 24*84 
 
 24*88 
 
 24-92 
 
 24*96 
 
 •2 
 
 25-00 
 
 25-05 
 
 25-10 
 
 25-15 
 
 25-20 
 
 25-25 
 
 25-30 
 
 25-35 
 
 25-40 
 
 25-45 
 
 '3 
 
 25'5o 
 
 25-55 
 
 25-60 
 
 25'65 
 
 25-70 
 
 25-75 
 
 25*80 
 
 25*85 
 
 25-90 
 
 25-95 
 
 *4 
 
 26*00 
 
 26*04 
 
 26-08 
 
 26*12 
 
 2616 
 
 26*20 
 
 26*24 
 
 26*28 
 
 26-32 
 
 26*^6 
 
 *5 
 
 26-40 
 
 26-45 
 
 26-50 
 
 26*55 
 
 26*60 
 
 26*65 
 
 26*70 
 
 26*75 
 
 26-80 
 
 26*85 
 
 •6 
 
 26-90 
 
 26-95 
 
 27*00 
 
 27-05 
 
 27*10 
 
 27*I5 
 
 27*20 
 
 27*25 
 
 27*30 
 
 27-35 
 
 7 
 
 27-40 
 
 27-44 
 
 27-48 
 
 27-52 
 
 27-56 
 
 27*6o 
 
 27*64 
 
 27*68 
 
 27-72 
 
 27-76 
 
 •8 
 
 27-80 
 
 27-85 
 
 27-90 
 
 27-95 
 
 28 00 
 
 28*05 
 
 28*10 
 
 28*15 
 
 28*20 
 
 28-25 
 
 *9 
 
 28-30 
 
 28-35 
 
 28-40 
 
 28-45 
 
 28*50 
 
 28-55 
 
 28*60 
 
 28*65 
 
 28*70 
 
 28*75 
 
202 
 
 FOOD. 
 
 Table showing Degrees of Spirit Indication with corresponding 
 Degrees of Gravity lost (continued). 
 
 Spirit in- J 
 dication. ' 
 
 
 
 
 Hundredths 
 
 of a degree. 
 
 
 
 
 Degrees 
 
 
 
 
 
 
 
 
 
 
 
 and 
 
 o'oo 
 
 O'OI 
 
 0'02 
 
 0*03 
 
 0*04 
 
 0*05 
 
 0-06 
 
 0*07 
 
 o - o8 
 
 0*09 
 
 tenths. 
 
 
 
 
 
 
 
 
 
 
 
 70 
 
 28-80 
 
 28*84 
 
 28*88 
 
 28*92 
 
 28*96 
 
 29*00 
 
 29-04 
 
 29-08 
 
 29*12 
 
 29-16 
 
 •I 
 
 29*20 
 
 29*25 
 
 29-30 
 
 29*35 
 
 29*40 
 
 29*45 
 
 29-50 
 
 29*55 
 
 29*60 
 
 29-65 
 
 *2 
 
 2970 
 
 29-75 
 
 29-80 
 
 29-85 
 
 29-90 
 
 29*95 
 
 30*00 
 
 30*05 
 
 3010 
 
 30-15 
 
 '3 
 
 30' 20 
 
 30-25 
 
 30-30 
 
 30*35 
 
 30-40 
 
 30*45 
 
 30-50 
 
 30*55 
 
 30-6o 
 
 30-65 
 
 •4 
 
 3070 
 
 30-75 
 
 30-80 
 
 30-85 
 
 30-90 
 
 30*95 
 
 3I-00 
 
 31*05 
 
 3I-IO 
 
 3i*i5 
 
 *5 
 
 31-20 
 
 31-25 
 
 3i-3o 
 
 3i*35 
 
 31-40 
 
 3'*45 
 
 31*50 
 
 3i'55 
 
 3I-6o 
 
 3i*65 
 
 •6 
 
 31-70 
 
 31-75 
 
 31-80 
 
 3i*85 
 
 31-90 
 
 3i'95 
 
 32*00 
 
 3205 
 
 32*10 
 
 32-15 
 
 7 
 
 32 20 
 
 32-25 
 
 32*30 
 
 32*35 
 
 32-40 
 
 32-45 
 
 32-50 
 
 32*55 
 
 32*6o 
 
 32*65 
 
 •8 
 
 32-70 
 
 32-75 
 
 32-80 
 
 32-85 
 
 32-90 
 
 32*95 
 
 3300 
 
 33*o5 
 
 33*io 
 
 33*15 
 
 •9 
 
 33-20 
 
 33*25 
 
 33*3o 
 
 33*35 
 
 33*40 
 
 33*45 
 
 33*50 
 
 33*55 
 
 33*6o 
 
 33*65 
 
 80 
 
 3370 
 
 33*76 
 
 33*82 
 
 33*88 
 
 33*94 
 
 34*00 
 
 34-o6 
 
 34*12 
 
 34"i8 
 
 34*24 
 
 •1 
 
 34*30 
 
 34'35 
 
 34*40 
 
 34'45 
 
 34-5o 
 
 34*55 
 
 34*6o 
 
 34*65 
 
 34*7o 
 
 34 75 
 
 •2 
 
 34-80 
 
 34-86 
 
 34-92 
 
 34-98 
 
 35-o5 
 
 35'io 
 
 35*i6 
 
 35*22 
 
 33*28 
 
 35*34 
 
 •3 
 
 35 '4o 
 
 35*45 
 
 35*50 
 
 35*55 
 
 35-6o 
 
 35*65 
 
 357o 
 
 35*75 
 
 35*8o 
 
 35*85 
 
 '4 
 
 35*90 
 
 35*96 
 
 36-02 
 
 36-08 
 
 36-14 
 
 36*20 
 
 36-26 
 
 36*32 
 
 36-38 
 
 36*44 
 
 •5 
 
 36-50 
 
 36*55 
 
 36*60 
 
 3665 
 
 36-70 
 
 36*75 
 
 36-80 
 
 36*85 
 
 36*90 
 
 36-95 
 
 •6 
 
 37-00 
 
 37*o5 
 
 37*10 
 
 37*15 
 
 37*20 
 
 37*25 
 
 37'3o 
 
 37*35 
 
 37*40 
 
 37*45 
 
 7 
 
 37-5o 
 
 37*55 
 
 37-60 
 
 37*65 
 
 37*7o, 
 
 3775 
 
 37*8o 
 
 37*85 
 
 37-90 
 
 37-95 
 
 •8 
 
 38-00 
 
 38-06 
 
 38*12 
 
 38-18 
 
 38*24 
 
 38*3o 
 
 38*36 
 
 38*42 
 
 38*48 
 
 38*54 
 
 •9 
 
 38-60 
 
 38-65 
 
 38*7o 
 
 38*75 
 
 38-80 
 
 38*85 
 
 38*90 
 
 38-95 
 
 39*oo 
 
 39-05 
 
 90 
 
 39-10 
 
 39-16 
 
 39*22 
 
 39*28 
 
 39*34 
 
 39-40 
 
 39-46 
 
 39*52 
 
 39*58 
 
 39-64 
 
 •1 
 
 39-7o 
 
 39*75 
 
 '39*80 
 
 39-85 
 
 39*90 
 
 39-95 
 
 40*00 
 
 40-05 
 
 40*10 
 
 40*15 
 
 •2 
 
 40-20 
 
 40-25 
 
 40-30 
 
 40-35 
 
 40-40 
 
 40-45 
 
 40*50 
 
 4o*55 
 
 40-60 
 
 40-65 
 
 •3 
 
 40-70 
 
 40*75 
 
 40*80 
 
 40*85 
 
 40*90 
 
 40*95 
 
 41*00 
 
 41*05 
 
 41-10 
 
 4i*i5 
 
 *4 
 
 41-20 
 
 41*25 
 
 41-30 
 
 4i*35 
 
 41-40 
 
 41*45 
 
 4i*5o 
 
 4i*55 
 
 41-60 
 
 41*65 
 
 •5 
 
 41-70 
 
 4i*75 
 
 41*80 
 
 41*85 
 
 41*90 
 
 4i*95 
 
 42*00 
 
 42-05 
 
 42-10 
 
 42*15 
 
 •6 
 
 42*20 
 
 42*25 
 
 42*30 
 
 42-35 
 
 42*40 
 
 42*45 
 
 42*50 
 
 42*55 
 
 42-60 
 
 42-65 
 
 7 
 
 42-70 
 
 42*75 
 
 42*80 
 
 42-85 
 
 42*90 
 
 42*95 
 
 43-00 
 
 43*05 
 
 43-10 
 
 43*15 
 
 •8 
 
 43* 20 
 
 43*25 
 
 43*30 
 
 43-35 
 
 43*40 
 
 43*45 
 
 43*50 
 
 43*55 
 
 43-60 
 
 43-65 
 
 '9 
 
 437o 
 
 43*75 
 
 43*80 
 
 43-85 
 
 43'9o 
 
 43*95 
 
 44-00 
 
 44*05 
 
 44-10 
 
 44*15 
 
COMPOSITION OF WINES. 203 
 
 wines from Spain and Portugal ; but it excludes the so-called 
 British wines, which are not made from the juice of the grape at 
 all, and those wines from other countries, which are fortified with 
 spirit when they require no such addition. 
 
 When the sugary juice of a fruit, such as the grape, is left to 
 itself at a moderate temperature, fermentation takes place from 
 the influence and action of germs present in the air ; this process 
 differing very much from that in the making of beer, when the 
 starchy or sugary infusion or wort is boiled, and then yeast added 
 to make it ferment. During the fermentation of the fruit juice, 
 a part or whole of the sugar is converted into alcohol. Various 
 ethers, which give the characteristic flavour or bouquet to wine, 
 are formed, as well as acetic, malic, succinic, and other acids. 
 The essential acid of wine is tartaric acid ; much of this crystal- 
 lizes in the casks as cream of tartar or tartrate of potash. The 
 newer wines contain aldehyd, which is very intoxicating ; later on 
 this gets oxidized into acetic acid, and if exposed to the air long 
 enough, all the alcohol in a wine will be converted into this acid 
 so as to practically become ordinary wine vinegar. Much of the 
 colour, taste, and character of wines depend upon how far they 
 are made from the grape juice only, or how much this is mixed 
 with the seeds and skins of the fruit. The seeds are rich in tannin 
 and a bitter principle, while the skins yield a colouring matter, 
 some flavouring principle, and tannin. 
 
 With regard to the amount of alcohol which a wine contains 
 there is no constancy. All wines can be divided according to 
 their alcoholic strength into two classes : the natural wines, con- 
 taining from 6 to 13 per cent, by weight of alcohol ; and the 
 fortified wines, containing from 12 to 22 per cent, by weight of 
 alcohol. The limit of alcoholic distinction between these two 
 great classes of wine will be more readily understood if it be 
 borne in mind that during the fermentation of any sugary liquid 
 or mass, that process at once ceases when the alcohol formed 
 reaches 14 per cent., so that any excess of alcohol over that 
 amount must, of necessity, have been added artificially. The 
 ports and sherries are all largely fortified with added alcohol ; 
 while many of the inferior clarets and champagnes are subject to 
 very similar additions. The strongly alcoholic and fortified wines 
 are slow to undergo change, hence keep well ; but the lighter and 
 natural wines deteriorate rapidly when exposed to air. 
 
 Like the alcohol, the sugar in wine varies much, being for the 
 most part in the form of fruit sugar. Sherries generally contain 
 about 8 grs. to the ounce. In Madeira it varies from 6 to 66 grs. 
 per ounce; in port, from 12 to 28 grs. In champagnes the average 
 is about 24 grs., but many of the dry champagnes contain none. 
 
204 
 
 FOOD. 
 
 Wine is acid from the presence of free acid and acid salts, such as 
 tartrate of potash. Wines which have been " plastered " or treated 
 with gypsum or plaster of Paris to clear them, as is the case with 
 many sherries, are deteriorated, owing to the loss of their tartrates. 
 The chief acids are tartaric, acetic, malic, tannic, succinic, carbonic, 
 and fatty acids. The usual acidity of wines, in terms of tartaric 
 acid, is about 2 grs. per ounce in sherry, 3 grs. in champagne, 
 4 grs. in port and the better kinds of claret, and 6 grs. or more 
 in the inferior clarets. The tannic acid is derived mainly from 
 the seeds and skins of the grape ; it is largely present in new port, 
 less so in Madeira and the Rhine wines. The amounts of alcohol 
 and degrees of acidity can be determined in wines in the same 
 manner as explained for beer. It is to the mutual reactions of 
 the acids and alcohols in wine that the formation and presence in 
 them of ethers is due, and it is really to these latter that wines 
 owe their special value as stimulants. The colouring matter of 
 wines is derived mainly from the grape skins ; by nature it is 
 greenish or blue, but becomes violet or red by the action of the 
 free acids in the wine. As wine ages, changes occur, resulting 
 in a precipitated combination of the organic bodies with tannic 
 acid, whereby the wine becomes pale and less astringent. Occa- 
 sionally, in the inferior wines, artificial colouring matter is added 
 in the form of the many varieties of aniline dyes, logwood, 
 cochineal, etc. The adulterations of wine are mainly in the 
 direction of added spirit, artificial colouring, and " plastering " to 
 secure clearness and dryness. 
 
 The term " dryness" as applied to wines is meant to express 
 a flavour which is not that of sweetness. It has already been 
 explained that the fermentation of grape juice in the formation of 
 wine is the result of a vegetable growth — that of a microscopic 
 fungus which the must, or juice of the grape, obtains spontaneously 
 from the atmosphere. Two distinct effects follow the growth of 
 this fungus or process of fermentation : one is, the sugar of the 
 must or grape juice is converted into alcohol ; secondly, the 
 greater part of the albuminous or nitrogenous part of the must is 
 consumed as food by the fungus. If left alone, the fermentation 
 goes on until either all the sugar is used up or until the supply of 
 sufficient albuminous matter is exhausted. Now, it will readily 
 be understood that the relative proportions of these present deter- 
 mine which of the two gets exhausted first ; and if the sugar is 
 used up before the albuminous food of the fungus, a dry or not 
 sweet wine is produced, while if the nitrogenous food is exhausted 
 first, the remaining unfermented sugar produces a sweet wine. 
 Since the juice of the ripe grape contains from 10 to 30 per cent. 
 of sugar, there is a very wide range. 
 
COMPOSITION OF WINES. 205 
 
 A large number of people dislike sweet wines, hence the 
 demand for what is called a dry wine. From what has been 
 stated as to the difference in origin of a naturally sweet wine and 
 a naturally dry wine, it will be apparent that the poorer the grape 
 the drier the wine made from it ; but the yield from a poor grape 
 is less than that from a rich one, hence naturally dry wine costs 
 more to produce than naturally sweet wine. It will also be 
 apparent that the conversion of naturally sweet wines into dry 
 ones will not be difficult, and since there is a demand for dry 
 wines the artificial conversion is frequently performed. It is 
 carried out either by making the wine from unripe or poor grapes, 
 in which case the yield of alcohol and flavour are both low; or 
 it is done by adding some nitrogenous material such as gelatin, 
 isinglass, or white of egg to the must, so as to feed the yeast 
 fungus until all, or nearly all, the sugar in the grape has been 
 converted into alcohol. This procedure is sometimes called 
 finings in the wine trade, and is the least objectionable of all 
 methods of artificial drying, being, as it is, almost identical with 
 the natural cause of wine drvness. Unfortunatelv, there are other 
 methods adopted which are less commendable but more common. 
 These consist often in making an imitation of the natural dryness 
 of wine bv adding factitious salts and fortifying with alcohol. The 
 sugar still exists as largelv as before, only its taste is disguised. 
 
 Perhaps the most general method of increasing the dryness of 
 a given wine is that of adding mineral acids and mineral salts, 
 more particularly gypsum. This is technically known as 
 " plastering," because gypsum is plaster of Paris. This being 
 largely sulphate of calcium modifies the chemical characters of 
 the wine by decomposing the cream of tartar or potassium tartrate 
 into calcium tartrate, potassium sulphate, and free tartaric acid, 
 at the same time altering the colouring matter and changing the 
 neutral organic compounds which exist in grape juice. Tne use 
 of gypsum materially clears a wine, making it look brilliant ; this 
 is explained by the fact that the resulting sulphate of potash is 
 much more soluble than the antecedent tartrate of potash. To a 
 certain extent, after the addition of gypsum, much of the tartaric 
 acid of wine is replaced by sulphuric acid, a body which renders 
 wine, so altered, distinctly unsuitable for daily use. The sherries 
 suffer the most from plastering — so much so, that some chemists 
 advise that the plastering of wines should be called adulteration. 
 
 The nutritive value of the wines is small, and in the main 
 subsidiary to the stimulating properties of their contained alcohol. 
 The clarets and lighter wines are more or less antiscorbutic, owing 
 to the presence of the organic acids. Port and sherry appear to 
 predispose to gout. The presence of some albuminous principle 
 
206 FOOD. 
 
 in wine may give it a slight nourishing value, but in favour of such 
 a view the evidence is small. 
 
 Of all the alcoholic beverages, spirits contain the largest 
 amount of alcohol. .They are all made by the distillation of 
 alcohol from the fermentation of various saccharine or starchy 
 materials. The more common spirits in this country are brandy, 
 whisky, rum, and gin. The basis of all of them is ethylic alcohol, 
 mixed with water ; but they all contain other alcohols, usually 
 classed together under the name of fusel oil, various compound 
 ethers, and fragrant bodies produced during distillation. It is 
 the varying proportions of these latter which give the respective 
 spirits their characteristic taste and aroma. After being kept for 
 some years, spirits become mellowed or softened down ; this was 
 formerly supposed to be due to the diminution of the so-called 
 fusel oil, but it is now more generally regarded as due to a lessen- 
 ing both in quantity and quality of the empyreumatic or flavouring 
 substances. 
 
 Brandy is made by the distillation of fermented grape juice. 
 When first distilled it is colourless, but gradually darkens with 
 age, though too often artificially coloured by means of burnt 
 sugar. Pure brandy consists of water, alcohol, acetic acid, acetic 
 and cenanthic ethers, a volatile oil, colouring matter, and tannin. 
 It usually contains from 46 to 55 per cent, of alcohol. The best 
 kinds come from France, the more inferior from Spain, Portugal, 
 and Italy. The chief adulterations are water, cayenne pepper, 
 burnt sugar, and acetic ether. Some of the cheaper brandies are 
 not made from grape juice at all, but are mere imitations, made 
 from corn spirit, flavoured and coloured. According to Blyth, a 
 very usual process of making brandy artificially in England is to 
 add to every 100 parts of proof spirit from J to 1 lb. of argol, 
 some bruised French plums, and a quart of good Cognac; the 
 mixture is then distilled, and a little acetic ether, tannin, and 
 burnt sugar added afterwards. 
 
 Whisky is really one of the corn spirits, being made from 
 malted grain. The more inferior kinds are prepared from oats, 
 barley, or rye, or from potatoes mashed up with malted barley 
 and then roughly distilled and burnt in order to give it the 
 peculiar smoky flavour characteristic of some varieties. Whisky 
 usually contains from 40 to 50 per cent, of alcohol. Its adultera- 
 tions are much the same as those of brandy. 
 
 Rum is a spirit obtained by distillation from the fermented 
 skimmings of sugar-boilers or the drainings of sugar-barrels 
 (molasses). Like brandy, it is colourless when first distilled, but 
 it is later on artificially coloured with burnt sugar. Rum is chiefly 
 made in Jamaica, and, owing to the habit there of putting a few 
 
GIN. 207 
 
 slices of pine-apple into the best qualities, it is often flavoured 
 with that fruit. The peculiar flavour of rum is due to butyric 
 ether and a volatile oil ; the amount of alcohol present in rum is 
 from 50 to 60 per cent. An imitation flavouring identical with 
 that of the Jamaica rum flavoured with pine-apple is made by 
 distilling butter with sulphuric acid and alcohol, and then, by 
 means of the resulting butyric compound, a factitious rum can be 
 made from malt or molasses spirit. 
 
 Gin in this country is usually made from a mixture of malt 
 and barley, flavoured not only with juniper berries but with oil of 
 turpentine, orange peel, and several other aromatic substances. 
 In Holland it is made from unmalted rye and barley malt, with 
 juniper berries. In consequence of the juniper and turpentine 
 contained in gin, it is a direct stimulant to the kidneys. It usually 
 contains from 49 to 60 per cent, of alcohol. Its chief adultera- 
 tion is water, which makes it turbid; to remove this, alum and 
 acetate of lead are employed, followed by the addition of sugar 
 and cayenne pepper to sweeten it and give it pungency. Speak- 
 ing generally, gin is the spirit of which most is annually consumed 
 by the public, and the spirit which is most often adulterated. 
 
 Unless expressly stated to be otherwise, brandy, whisky, and 
 rum are expected by law to be sold of not less alcoholic strength 
 than 25 degrees below proof, while gin should not be less than 35 
 degrees under proof spirit ; of course, in the other direction, or 
 over proof, there is no limit. 
 
 CHAPTER IV. 
 
 SOILS, SITES, AND BUILDINGS. 
 
 Whatever may have been the mode of origin of our earth, there 
 is little doubt that there came a period when its crust solidified 
 and formed what are called igneous rocks. This rock was sub- 
 jected through long periods of time to the wearing action of 
 rain, frost, and wind, with the result that much of it was worn down 
 into fine particles, which, collecting together, contributed to the 
 formation of another class, called secondary or sedimentary rocks. 
 Soils. — Now, it is of these two kinds of rocks that the great 
 mass of the earth is composed in the present day, examples of 
 the igneous rocks being granite, basalt, and volcanic lava, while 
 
208 SOILS, SITES, AND BUILDINGS. 
 
 representing the sedimentary rocks are the various sandstones, 
 greensands, limestone, chalk, gravel, and clays. The surface of 
 the ground, or soil, is really only the result of the gradual wearing 
 or breaking up, as it were, through many ages, of these various 
 rocks of which our globe is mainly constituted. It is convenient 
 to divide the soil into two parts — namely, a deeper portion, or sub- 
 soil, consisting chiefly of inorganic materials, the direct result of 
 the breaking up of the rock under various agencies ; and an upper 
 portion, or surface soil, which, again, is derived partly from the 
 inorganic subsoil and partly from the products of the decomposi- 
 tion of animal and vegetable (organic) matter. 
 
 The nature of the surface soil varies considerably in different 
 places, consisting not only of the decayed upper surface of rocks 
 beneath, mixed with the remains of animal and vegetable matter, 
 but also of much alluvial deposit, or material brought by running 
 water from neighbouring or distant districts. To this action 
 must be added the constant transposition of soil by earthworms, 
 ants, moles, rabbits, and other animals, the general effect of which 
 is to disintegrate the soil, riddle it with holes or burrows, and to 
 admit air into its deeper parts. 
 
 Allusion has been made to the presence in the surface soil of 
 the products of the changes which organic substances undergo in 
 it. These changes, which are chiefly in the direciion of oxida- 
 tion, but occasionally in that of reduction, are largely the result 
 of the action of bacteria present in the soil, these micro-organisms 
 being much more numerous in the superficial layers than at a 
 greater depth. The most important property possessed by soil, 
 owing to the presence in it of micro-organisms, is that of nitrifica- 
 tion, whereby organic matter is decomposed into its simplest con- 
 stituents, so as to be readily made use of by vegetation. True, 
 the greater number of the bacterial forms present in the upper 
 soil layers are incapable of causing disease in man, still, certain 
 micro-organisms which are capable of producing human disease 
 are occasionally met with in the earth. The chief of these are 
 the bacilli of tetanus or lock-jaw, of anthrax, of glanders, of 
 enteric fever, and of a peculiar disease known as malignant 
 oedema. That micro-organisms capable of causing disease in man 
 do exist in soil is beyond doubt, but, fortunately, their power for 
 doing harm appears to be extremely small. 
 
 In a general sense, as influencing health, soils need to be 
 considered not only as to the nature and number of their con- 
 tained micro-organisms, but also in regard to the amount of 
 moisture and air in them and their capacity for heat. The mois- 
 ture in soil is derived from two sources — namely, from the rain, 
 and from the subsoil water beneath. This latter is sometimes 
 
WATER AND AIR IN SOIL. 2CX) 
 
 known as the groundwater and the depth at which it will be found 
 varies in different places, being in some localities within a few 
 inches of the surface of the ground, and in others only some ten 
 to hundreds of feet below. Above the level of the ground water 
 the soil is kept moist by capillary attraction and by evaporation 
 of the water below, by rainfall and by movements of the ground 
 water ; on the other hand, the upper soil layers are constantly 
 losing moisture by evaporation from the surface and through 
 vegetation. When the ground water rises, it forces air out of the 
 soil, and at the same time may pollute wells by bringing into them 
 the washings of impure soils. When it falls again it leaves the 
 soil, of course, moist and full of air. The variations in the move- 
 ments and height of the ground water are conveniently measured 
 by noting the water-level in wells j but, to be reliable, this needs 
 to be done frequently and simultaneously in the wells over a large 
 area, so as to avoid any error due to purely local conditions. 
 
 The nature of a soil will largely influence the amount of 
 moisture which it will take up or retain, and practically there are 
 no soils which are not capable of holding some moisture. In 
 regard to water, all soils have two actions, namely, permeability 
 and absorbability. The permeability of a soil to water is practi- 
 cally identical with the speed at which percolation takes place 
 through it. Observations show that water passes most slowly 
 through clay, and with increasing swiftness through marls, loams, 
 limestones, chalks, coarse gravels, and fine sands. Even through 
 chalk, percolation is by no means rapid. Percolation is most 
 rapid when soil is saturated with moisture. From results by 
 many observations, it would appear that the capacity of soils for 
 moisture increases with the amount of organic substances 
 present ; decomposition is most active in soils when the 
 moisture is about 4 per cent., but can continue when it is as low 
 as 2 per cent. ; any excess over 4 per cent, seems to retard 
 decomposition changes in soil. 
 
 Above the level of the ground water, all soils contain air, and 
 this is sometimes called the ground air, because it fills all the 
 space not occupied by either water or solid particles. Its amount 
 varies with the degree of looseness of the soil. In its composition, 
 ground air more or less resembles that of the atmosphere above the 
 earth — that is to say, it contains moisture, organic matter, oxygen, 
 nitrogen, carbon dioxide, and occasionally ammonia, marsh gas, 
 sulphuretted hydrogen, and other products of fermentation and 
 decomposition. The oxygen in ground air decreases with the 
 depth, while the carbon dioxide increases with the depth below 
 the surface. The amount of nitrogen in ground air is fairly 
 constant and approximates to that present in the atmosphere. 
 
210 SOILS, SITES, AND BUILDINGS. 
 
 The ground air, like the ground water, is constantly moving, the 
 chief influences being wind, the percolation ot rain, the rise and 
 fall of ground water, and variations in temperature and barometric 
 pressure. Heavy rains will not only force ground air to a deeper 
 level, but will also force it out of the ground at places which 
 are dry, as, for instance, the basements of houses. The effect of 
 variations in level of the ground water in producing corresponding 
 movement in the ground air has already been mentioned ; while 
 probably of even greater importance are the changes in temperature 
 and barometric pressure. The temperatures of the atmospheric 
 and ground airs are seldom the same, with the result that 
 there is a constant ebbing and flowing of air in and out of the 
 soil. As illustrating these effects of different air temperatures, 
 allusion maybe made to the aspirating power which warm houses, 
 unprovided with impermeable basements, have in drawing air up 
 out of the ground. In the same way, foul air from defective 
 drains may contaminate houses unless an impermeable layer is 
 placed between the house basement and the ground. 
 
 Not only do some soils contain more moisture and air than 
 others, but they are also more easily heated. These variations 
 depend mainly on their looseness and colour. To a certain 
 extent, variations in the heat of soils depend upon that of the 
 atmosphere, the daily variations ceasing to be susceptible below 
 4 feet from the surface. As judged by their relative power for 
 losing heat, soils appear to stand in the following order : — Clays, 
 loams, marls, chalk, and sands. Sands not only warm more 
 rapidly than other soils, but also appear to retain their heat 
 better, while clays not only warm more slowly than sands, but 
 lose heat more rapidly. Owing to the slowness with which water 
 absorbs heat, all moist soils are slow to warm and invariably 
 constitute what are called " cold soils." At first sight, it may not 
 appear that the temperature of the soil has any very important 
 bearing upon health, but apart from its influence upon the various 
 processes of either decay or oxidation going on within the soil 
 itself, the temperature of the ground has a direct influence upon 
 the temperature of the atmosphere and also upon many of the 
 conditions which are implied by the word "climate." In this 
 connection, the relative degrees of warmth or coldness, of dryness 
 or moistness, of purity or impurity of soils, are of the very greatest 
 importance in estimating the value of any particular soil or ground 
 as a site for dwellings or buildings. 
 
 Sites. — Although the choice of sites for our houses in towns 
 and villages is usually sacrificed to expediency or necessity, and 
 more often than not fixed upon regardless of the advice of any 
 one, still, some knowledge of the chief considerations which should 
 
SITES. -211 
 
 rule the selection of a building site is none the less necessary. 
 In considering the aspect of any particular site, it may be said 
 that the brighest and most airy house is usually the healthiest. 
 
 In the simpler type of house, where the front has a north- 
 erly aspect, the living room should extend through the whole 
 depth of the building with windows at both ends to secure sun- 
 light from the back of the house. Houses with a northerly 
 aspect to the front will generally require longer site frontages 
 than those with a southerly aspect. 
 
 As regards the ground or soil on which it is proposed to 
 build, our aim should be to secure either a naturally dry place, or 
 one at least easily drained, and into which the drainage from 
 other spots does not and is not likely to flow. For this reason, 
 all low-lying swamps and hollows should be avoided. If the 
 district is generally level, every advantage should be taken of 
 any slight elevation in order that the house may be built as 
 high as possible. If, on the other hand, it is a hilly country, the 
 actual slopes or sides of a hill are not usually good situations for 
 houses. No dwelling should be built close in to a hill, as it is 
 sure to be damp, and proportionately unhealthy. It is preferable 
 to build either on the actual top of a hill or on a terrace or spur 
 some little way off the hill itself. For similar reasons, the banks 
 of rivers, unless well raised above the highest level of the water, 
 are to be avoided. Such localities are difficult to drain, usually 
 very damp, and liable to be flooded. 
 
 Wherever possible, the soil or ground itself ought to be 
 porous, such as gravel or sand, which allow of water running 
 freely away, and do not cause it to collect about the house. The 
 next best soils on which to build are rocks, such as granites, clay, 
 slates, limestones, sandstones, or chalk ; these nearly always have 
 a good slope, and drain easily. The loams and stiff clays are not 
 as a rule good soils for building purposes, as, unless well drained, 
 they are apt to hold water ; if, however, adequately drained, these 
 are not necessarily unhealthy. Pure chalk forms a healthy site, 
 being permeable; if the chalk be mixed with clay (marl), or be 
 underlaid by clay, it becomes impermeable and damp. If of 
 any thickness, gravel beds make good building sites. The worst 
 soils are the shallow beds of gravel or sand lying on clay ; these 
 are frequently waterlogged and proportionately bad; the same 
 remark applies to reclaimed lands near the mouths of rivers, and 
 the so-called alluvial lands, which consist of soils that are really 
 the deposit or sludge from rivers. Alluvial tracts are almost 
 invariably unhealthy, owing to their dampness. 
 
 In towns and modern cities, care should be taken that no 
 artificial site be chosen — that is, one placed upon a so-called 
 
212 SOILS, SITES, AND BUILDINGS. 
 
 " made soil," which is really a soil made up of rubbish. The 
 rubbish usually composing such soils is peculiarly rich in 
 decomposing organic matter liable to give rise to particularly 
 injurious products. It is certainly unsafe to build upon any 
 such made soil until the rubbish of which it is so largely com- 
 posed has been exposed to the sun and air for quite three 
 years, and even then the dwelling built upon it should have an 
 air-proof basement of concrete, or some impermeable material. 
 
 This concrete should be from 4 to 6 inches thick, and may, 
 in some cases, be made to serve as a floor itself, particularly in 
 passages, washhouses, sculleries, and pantries. If the expense of 
 this be objected to, a layer of well-puddled clay is probably the 
 next best thing, or, if neither of these arrangements be adopted, 
 and a boarded-rloor basement is used, a space of at least 9 inches 
 has to be left between the under side of the floor and the ground 
 surface, not only for ventilation and as a preservative against dry 
 rot, but also as a means of disconnection between the soil air and 
 the air of the house. In some places it is necessary to raise the 
 building on arches to keep it sufficiently clear of the ground ; but, 
 in any case, there ought to be some distance between the founda- 
 tions and the floor of the lowest rooms, while the space so left 
 should be ventilated. As a rule, cellars under houses add to 
 their healthiness, especially if properly built with an impervious 
 flooring, and adequately ventilated. 
 
 In all sites, it is important to notice the distance of the ground 
 water from the surface. As already explained, if this water be 
 too near the ground-level, the spot will be damp ; it ought never 
 to be nearer the surface than 10 feet, and, if possible, should be 
 at least 15 or 20 feet below the ground-line. There is good 
 reason to believe that frequent, sudden, and extensive changes of 
 water-level are specially unhealthy ; therefore a place where the 
 level of water in a well is apt to rise and fall a good deal is not a 
 good site. These remarks apply as much to towns as to country, 
 for often one part of a town may be less healthy than another on 
 account of its situation being lower, and the level of the ground- 
 water higher. Statistics for many years go to show that where 
 the ground-water level has been lowered, and the soil made drier 
 by means of drainage, there the public health has improved. 
 
 In judging of the influence of surroundings upon the whole- 
 someness of a given site, it is necessary to assure one's self that 
 the soil or subsoil is not being fouled by the drainage of any 
 neighbouring building. Thus, w r hen one house lies at a lower 
 level than another near it, it is likely to suffer from the effects of 
 the drainage from the one above. In cases where houses stand 
 alone, as in rural districts, special care needs to be taken that no 
 
SELECTION OF BUILDING SITES. 21 3 
 
 heaps of farm refuse or manure, cesspits, middens, or other col- 
 lections of decaying matter are allowed to remain near the house. 
 The immediate neighbourhood of sewage-farms are undesirable, 
 as, too, are the vicinities of factories, chemical works, graveyards, 
 and marshes, the air of which districts are apt to be impure from 
 either refuse or generated gases. The irrigation of adjoining 
 land, as a rule, makes a site less healthy than it ought to be, 
 especially if the irrigation be carelessly carried out, as this raises 
 the level of the ground-water. 
 
 In towns, those houses are generally the healthiest which 
 are built in wide roads or squares permitting a free circulation 
 of air. Narrow courts, alleys, and back-to-back houses should 
 be avoided. The evils of these latter houses have been re- 
 peatedly pointed out ; in them, through ventilation is not to be 
 obtained ; their sculleries, store-rooms, and pantries are nearly 
 always ill-ventilated, dark, and difficult to keep clean, while- their 
 closets have to be built in blocks, and are frequently, if not in 
 an actually public position, at an inconvenient distance. The 
 areas or basements of nearly all houses are unhealthy, being 
 usually dark, frequently damp, ill-ventilated, and rarely whole- 
 some. Although it is important that houses should be freely 
 open to both air and light, still the circumstances of towns and 
 cities prevent these conditions being attained so readily as in 
 the country. To obviate as far as possible light and ventilation 
 being interfered with by houses being too near each other, it is 
 now ordered in London and in the larger towns that all new 
 streets shall be at least as wide as the houses on either side of 
 them are high, and that no new street be less than forty feet wide. 
 As a matter of fact, sunlight is very rapidly obscured if houses 
 face one another at less distance than seventy feet. 
 
 Assuming the selection of a building site has been made, the 
 first step is to see that the lay-out is made with due regard to 
 economy of space and utilitarian requirements. As a rule not 
 more than 12 houses to the acre should be built on a site in an 
 urban area and not more than 8 to the acre in rural areas. 
 Roads should be planned with due regard to gradients and the 
 subsequent drainage scheme. Minor roads should be planned to 
 afford the best building frontages and so as not to attract through 
 traffic. The next step is to ensure that the building or buildings 
 to be erected on the site are so constructed as to be healthy. To 
 that end they must be able to be kept free from damp, to be proof 
 against weather, and to maintain the air within it pure and whole- 
 some. These indispensable conditions, applicable equally to the 
 private dwelling-house or to public institutions, involve attention 
 being directed to the way in which the foundations and brickwork 
 
214 SOILS, SITES, AND BUILDINGS. 
 
 are arranged, to the material and state of the outer walls and roof, 
 to those of the inside walls, ceilings, and floors, as well as to the 
 general arrangements of the building, and the means for removing 
 excreta and refuse. 
 
 Dwelling-houses. — In respect of general arrangements it is 
 impossible to state more than general principles, as both the size 
 and style involve many alternatives. Speaking generally and 
 ideally, the door or entrance should be protected from the pre- 
 vailing wind either by actual position or by means of some special 
 protection, such as a porch. Every house should have, both in 
 front and back of it, an open space at least equal in length to its 
 own height, so as to allow sufficient light and ventilation for the 
 rooms on the lowest floor. 
 
 In this country the living-rooms should, as far as possible, 
 face the south and west, so as to be both bright and cheerful. 
 The north is best allotted to working-rooms and the dining-room, 
 as twilight lasts longest there ; the staircases are also best 
 when arranged upon this side of the house, being always cool. 
 For the larder, pantry, or dairy, this aspect is exceptionally 
 good. Bedrooms will be found most comfortable when facing 
 the north-east, as they get a pleasant morning sun, and are 
 correspondingly cool at night. The east is suitable for the 
 breakfast-room, morning-room, and library, but not for the 
 drawing-room, as it lacks the afternoon sunshine. In the south- 
 east may be placed bedrooms, and for rooms used by the sick 
 this aspect cannot be surpassed for fitness. The south is un- 
 suited for dining-room windows, unless there be a good verandah ; 
 the south-west and west are not good aspects for bedrooms or 
 dining-rooms, as, under the influence of the afternoon sun, rooms 
 on this side of a house are apt to get unpleasantly hot. Where 
 a bedroom is occupied only as a sleeping-room, aspect is of the 
 least importance. By the aid and study of the compass, the 
 principal points with regard to aspect and light will be readily 
 seen. 
 
 For houses of a less ambitious kind, such as the self-contained 
 two-storey cottage type, the following general scheme is suggested. 
 Each house should include, if possible, a living-room, scullery, 
 larder, fuel store, w.c, bath in separate chamber, and three bed- 
 rooms. 
 
 The living-room should be arranged with as few doors as 
 practicable, these being placed so that they will not interfere with 
 the comfort of those occupying the space about window or fire. 
 The best aspect is south-east. The cooking range, whether in 
 this room or scullery, should be placed on a wall at right angles 
 to a window wall. If there is a parlour as well, its best aspect is 
 
SELECTION OF BUILDING SITES. 21 5 
 
 a westerly one. Neither the living-room nor parlour should have 
 less floor space than 180 square feet. The scullery should provide 
 80 square feet of space, but this may be reduced where washing 
 is provided for in bathroom or in a washhouse. The sink should 
 be under or near a window. The copper should have a steam 
 outlet. The point to be avoided is making the scullery sufficiently 
 large as to encourage its use as a living-room. The larder should 
 be on the north side of the house, and if possible with a window 
 screened from the sun. Usually its size should be from 12 to 16 
 square feet. The coal-store should be capable of holding at least 
 one ton of coal, and not less than 15 square feet is desirable for 
 this purpose. It should be so placed that coal can be delivered 
 from the outside and fetched for use under cover. The bath 
 should, if possible, be in a separate compartment of its own. 
 Hot water should be made available both to the bath and the 
 sink in the scullery. The water-closet should be accessible under 
 cover, or in larger houses it may be on the first floor. If so 
 placed it must ventilate direct to outside the house and not into 
 any room or passage-way. Where there is an earth-closet it must 
 be constructed outside the house. The distance at which this is 
 placed should not be excessive, neither should groups of closets 
 common to two or more houses be placed in yards in which 
 children play, women han^f out their washing, or men and boys 
 loiter. The stairs should start from the entrance lobby with a 
 window to light and ventilate the landing. The bedrooms should 
 be placed as far as possible on the sunny side of the house. In 
 size, one should provide 150 square feet of space, another at 
 least 100 square feet, and the third and fourth, if there be four, 
 not less than 70 square feet. Two of the bedrooms should have 
 fireplaces, and if no fireplace adequately ventilated. In every 
 bedroom there should be one window at least of which the top is 
 6J feet from the floor. All ground-floor rooms should be not less 
 than 9 feet in height and the upper rooms not less than 8 feet in 
 height. The height of window-sills from the floor of all rooms 
 should be about 2 J feet, and the window area not less than one- 
 tenth of the floor area with adequate opening parts. The width 
 of fireplace openings should be not less than 3 feet for cooking 
 ranges, ij feet for parlours and living-rooms, and 14 inches for 
 bedrooms. Detached outbuildings for coal or w.c. should be 
 avoided in urban or suburban areas. 
 
 The dwelling of the town-living artisan offers special diffi- 
 culties in arrangement, because it is usually necessary to place 
 it upon sites where land is expensive and limited in extent. The 
 separate houses as usually built in rows should differ little from 
 the standards just given for the so-called self-contained two- 
 
2l6 SOILS, SITES, AND BUILDINGS. 
 
 storey cottage ; but the modern blocks of artisan dwellings occa- 
 sionally present unnecessarily objectionable features. Some of 
 the earlier built dwellings of this class were arranged on both 
 sides of a main corridor 8 feet wide in each storey. This cor- 
 ridor arrangement, besides conducing to want of privacy and 
 independence, involved much difficulty in regard to both light 
 and ventilation. A further defect in some of these blocks is the 
 provision of a water-closet as an integral part of each dwelling, 
 and too often so placed as to be a source of danger to health. 
 The corridors should be dispensed with, and each dwelling be 
 made independent of its neighbour for air by having vertical 
 series of dwellings only on each side of one or more staircases, 
 the other side of the dwellings being open to the outer air. The 
 water-closet accommodation should be improved by rendering it 
 accessible from each dwelling from the external air by means of 
 some sort of covered way or balcony ; while, by wholly detaching 
 the blocks of buildings, confined angles and stagnant corners will 
 be obviated. 
 
 As regards the actual structure of the dwelling-house the 
 following principles are of general application. The foundations 
 need to be sufficiently solid, and deep enough in the ground to 
 give firmness to the building. When the ground is soft, or a 
 solid foundation cannot be reached, the walls should be built 
 upon a solid platform of concrete or stone, which should be at 
 least four times as broad as the walls. The bases of the walls 
 themselves should be expanded into what are called footings, the 
 lowest course of which should be at least twice the breadth of 
 the wall. The height of the footings ought to be not less than 
 two-thirds of the wall thickness. 
 
 In all habitable buildings, to prevent damp rising in the walls 
 by capillary attraction, it is necessary to lay a damp-proof course 
 along the full thickness of the wall above the highest point at 
 which the wall is in contact with the earth, and below the lowest 
 timbers or floor supports. This course is either made of glazed 
 tile, slate, or sheet lead, asphalte or other impervious material. 
 The walls of no room or cellar should be in direct contact with 
 the soil. This can usually be secured by digging away the earth 
 on the outside to below the level of the floor, so as to form a 
 " dry area." An alternative plan is to make the wall hollow up 
 to a point above the ground-level, and then inserting two damp- 
 proof courses, one at the bottom of the hollow and below the 
 floor-level, the other at the top of the hollow, and therefore above 
 .the outside ground-level. By this means the inner wall is quite 
 shut off from the soil. Both these arrangements are shown in 
 the diagram (Fig. 27). 
 
SELECTION OF BUILDING SITES. 
 
 217 
 
 The materials used ordinarily for constructing the walls of 
 dwelling-houses are bricks, stones, cement either reinforced with 
 iron or not, and wood. Owing to bricks having been burnt, 
 during manufacture, they stand fire better than anything else, and 
 on this account, as well as their relative cheapness, are the best 
 
 *£s% •j-'.>' : -i ; .v' : V' '• •/■••- v. '.•V;.V 7 ; ^-i \ : . '■•■:- \'-«. -;-'• '• : .'\-£ *&'■.' v' • : -"-:'"^' -'• >\:.'.'.*.':?.\-i£i '. 
 Fig. 27. — Diagram showing placing of damp-proof courses. 
 
 and most commonly used material for house walls. They are 
 porous to air and water, and usually laid in beds or courses with 
 mortar. There are two ways of laying bricks, called respectively 
 English and Flemish bond. The English bond is a course of 
 bricks each showing one side alternating with a course in which 
 each shows an end (Fig. 28). Flemish bond is a single course of 
 bricks in which they alternately show a side and an end (Fig. 29). 
 The former method is considered to be the stronger, but not 
 easily adjusted to doors, windows or corners. 
 
 Owing to the absorbent and porous nature of all wall materials, 
 special care needs to be taken that outer walls do not admit damp 
 sideways, especially when in positions much exposed to driven 
 rain and wind. To prevent this, they may be hung over with 
 slate on the outer side, covered with glazed tiles, painted planks, 
 plastered, or cemented. A surface of mortar sprinkled with small 
 stones is occasionally employed. All these are good plans, pro- 
 vided they are done when the bricks are dry, as otherwise the 
 moisture is kept in the bricks. Painting the outside of a wall 
 
218 
 
 SOILS, SITES, AND BUILDINGS. 
 
 with silicate, or some indestructible paint, affords a similar pro- 
 tection, but, like the others, interferes with the insensible ventila- 
 tion or diffusion of air which so constantly goes on through the 
 walls of most inhabited buildings. Probably the best plan to 
 keep damp from coming through outer walls, is to build them 
 double, with a cavity or space two or three inches wide between 
 the inner and outer walls, and to join the two portions of such 
 a wall together by means of bondi?ig-ties of some non-absorbent 
 material, such as iron or glazed tiles. The bonding-plates 
 between the two walls should slope downwards and outwards, 
 otherwise the wet will pass across them to the inner side. In very 
 exposed positions, it may be necessary to place within the wall a 
 
 
 Fig. 28.— English bond. 
 
 I 
 
 Fig. 29. — Flemish bond. 
 
 vertical damp-proof course of iron or slate. A damp-proof course 
 is needed at the top of exposed walls, such as parapets and chim- 
 neys; this is usually provided by finishing the top of the wall 
 either with a stone and letting it project an inch or two over the 
 side, or by having an impervious damp-course laid in the wall or 
 chimney at its junction with the roof. During the building of 
 house walls, care should be taken that chimney flues are properly 
 constructed. They should all be made as straight as possible, 
 free of woodwork, and separate one from another. All chimneys 
 should be higher than surrounding buildings, so that they may be 
 in no way sheltered when the wind is in a certain direction, nor a 
 down-draught set up. 
 
CONSTRUCTION OF HOUSE WALLS. 219 
 
 The thickness of the outer walls of dwelling-houses is deter- 
 mined by the size and more particularly by the height of the 
 building. According to the Model Bye-laws, the minimum thick- 
 ness should be as follows: — Where a wall is not over 25 feet in 
 height, if it does not exceed 35 feet in length, and does not 
 comprise more than two storeys, it shall be 9 inches for its whole 
 height, but if it does comprise more than two storeys, or exceed 
 35 feet in length, it shall be 13 J inches below the topmost storey, 
 and 9 inches for the rest. Where walls are over 25 feet high, and 
 not exceeding 35 feet in length, they should be 13J inches thick 
 below the topmost storey, and 9 inches for the rest ; but if they 
 be longer than 35 feet, then they must be 18 inches thick for the 
 height of one storey, then 13 J inches thick for the rest of the 
 height below the topmost storey, and 9 inches thick for the rest 
 of its height. Walls over 35 feet high must be 18 inches thick 
 for the first two storeys, and 13 J inches for the rest. If over 50 
 feet in height, walls should be 22 inches thick for the height of one 
 storey, then 18 inches for the next two storeys, and finally 13 J 
 for the rest of the height. 
 
 Speaking generally, brick walls should be n-inch cavity walls 
 without special provision for air currents through the cavity. The 
 porosity of brickwork and its joints is sufficient for the necessary 
 changes of air, and if the cavity is ventilated its usefulness as a 
 non-conductor of heat or cold is destroyed. In most localities 
 a 9-inch solid brick wall without external protection will not be 
 weather-proof, and in some places precautions must be taken 
 even with an n-inch wall. In exposed positions the same con- 
 siderations apply to concrete walls. The cavity in brick and 
 other walls is usually two inches. All bricks built into walls for 
 ventilating purposes should be covered on the back with coarse 
 perforated zinc or fine galvanized wire mesh to prevent entry of 
 vermin, and a proper casing to the flue must be provided where 
 it crosses the wall cavity. If walls are constructed of concrete 
 they should be built with a continuous cavity and precautions 
 taken against condensation on the inner face. A suitable wall 
 should have a 4-inch inner face, a 3-inch outer face, and a 2-inch 
 cavity. Where local conditions favour the use of stone in place 
 of bricks, bath and similar stone ashlar, machine or hand cut to 
 4j-inch beds may be used and laid in courses equal to two or 
 three built brick courses. This is suitable for the outer face of 
 cavity walls, and where possible the inner face should be of 
 brick. Wood is occasionally used for making the upper walls 
 of houses j when so employed, it needs to be backed with at 
 least 4J inches of brickwork and well bonded together. Wood 
 covered with metal lathing and cement is not desirable. This 
 
220 SOILS, SITES, AND BUILDINGS. 
 
 objection does not apply to reinforced concrete, where all the 
 metal is encased in concrete and protected from rust. This form 
 of wall is somewhat expensive. 
 
 Roofs themselves need to be closely considered, as defects 
 in them are a frequent source of dampness. The more common 
 materials used in making roofs are slates and tiles, or less often 
 thatch, wood, zinc, and corrugated iron. Thatch forms a good 
 roof, being both warm and dry, but is apt to catch on fire, and, 
 unless well looked after, is rapidly infested and destroyed by 
 birds and vermin. Wood, covered with tarred felt or canvas, 
 makes an excellent roofing; but, like zinc and corrugated iron, 
 is practically only suited for temporary buildings, and is not 
 adapted for dwelling-houses. Lead is too costly to be used, 
 other than for special parts of the roof. In all roofings, it is 
 important to see that there is a framework, sufficiently strong 
 to bear the weight of the material, plus a certain amount of snow. 
 The framework is usually made of wood. If the covering is to 
 be of slates, the slope of the roof should be 30 ; if of tiles, 
 at least 45 ; metal roofs may be made flatter. House roofs 
 should always be covered with boarding laid at right angles to the 
 rafters of the framework, and, if possible, with a layer of some 
 good non-conducting material such as felt, which not only makes 
 the house cooler in summer, but warmer in winter. Laths are 
 occasionally substituted for boards in roofs ; this should not 
 be, as they are much less satisfactory. When siates are used, 
 they should be fastened to the boards with copper or zinc nails 
 (not iron), and made to overlap the row below them by quite 2 
 inches. Tiles are often fastened with wooden pegs, or hung on 
 by two special projections. Lead, zinc, and iron roofs are laid 
 nearly flat in widths, with their edges overlapping, to allow 
 for expansion and contraction. In some parts of the country, 
 flat stones are used for roofing, as in the sandstone districts. 
 These roofs are very heavy, and extremely difficult to make 
 water-tight. The gutters round chimneys or party walls, where 
 they join the roof, are frequent places for leaks ; thev all should 
 be made of lead, the edges of which should be well fixed into the 
 brickwork ; cement should never be employed for this purpose, as 
 it readily cracks. In all cases, the eaves of a roof ought to come 
 out some distance beyond the walls, and be provided with a good 
 gutter, so as to throw off the rain well away from the house. 
 These gutters should be of iron, and at least 2 inches from the 
 wall, discharging into rain pipes, which should also be of iron, 
 and placed well outside, and away from the house wall. These 
 rain-water pipes should either discharge into properly ventilated 
 rain-water tanks, or over a drain covered by a grating. They 
 
ROOFS. 221 
 
 should never be directly connected with drains or sewers, neither 
 should they be placed with their heads just below bedroom 
 windows, more particularly when they empty into a tank. 
 
 So far we have considered how to keep the outside walls 
 of the house dry, or at least how to prevent the damp reaching 
 the inside. It is now necessary to consider the inside walls, 
 ceilings, and floors. The inner walls of a house need to be 
 protected and covered in some way, though some people object 
 to it on the ground that it interferes with the porosity of the 
 walls, and so impedes ventilation. In this climate, however, some 
 wall covering is more or less of a necessity. The simplest is 
 white-washing. This plan, however, is not good, as it does 
 not do away with the porosity of the brick, and, moreover, leaves 
 a comparatively rough surface for dirt to lodge and collect. If 
 walls are white-washed, the wash must be frequently renewed. 
 The best plan is to aim at securing, not only an impervious 
 material, but one which has a smooth surface and can be readily 
 cleaned. For this purpose, two plans can be employed ; either 
 cover the walls with glazed tiles, or plaster them, and then paint 
 with some form of indestructible paint. Papering walls is very 
 common, but it has the disadvantage that, unless varnished, 
 it cannot be washed, and much dirt sticks. The flock papers and 
 their cheap imitations are particular offenders in these respects. 
 Lime-washing is preferable to common unglazed or flock papers ; 
 but it must be borne in mind that the mere putting on of a fresh 
 coat of lime-wash over an old and dirty one is not cleanliness ; 
 the wall should be first scraped, and the old coat thoroughly 
 removed. Similar objections exist to the too frequent habit of 
 pasting new wall-papers over old. This often goes on for times 
 together, until half a dozen or more papers are found one under 
 the other. Each of these will have taken up its share of dirt, and 
 each will have been laid on with a fresh supply of paste, so that, 
 on the slightest dampness, the whole has every facility for rotting 
 and fermenting. In all cases, the old paper should be scraped 
 off before the new one is put on. 
 
 Ceili?igs are mostly made of plaster worked on to laths, fixed 
 beneath the floor of a room above, and then either painted, 
 distempered with colour wash, white-washed, or else covered 
 with paper. The only advantage of the lath-and-plaster ceiling 
 appears to be its power of deadening sound. It is probable that 
 for health reasons it would be much better if ceilings were made 
 wholly of wood, but in that case, to deaden sound, they might 
 advantageously be backed by either silicated felt, or silicated 
 cotton, and to avoid dust coming through from floors above, have 
 the wood panelled, and all joints accurately tongued and grooved. 
 
222 SOILS, SITES, AND BUILDINGS. 
 
 Like wall coverings, Floors are best made of impervious 
 materials, which can be washed. Wood, stone, or tile constitute 
 the chief. Stones or tiles are very good for sculleries and 
 passages, but are apt to be cold for kitchens and living-rooms. 
 Wood makes the best flooring, particularly hard wood, such as 
 oak or teak, laid as parquet flooring. These, however, are very 
 expensive ; and the ordinary wood floor is usually made of 
 deal. In the majority of cases, floors are badly constructed, ill- 
 seasoned wood being used, which soon shrinks and gapes. Even 
 if made of deal, a floor can be well laid down, if care be taken to 
 tongue and groove the planks which constitute it, or if this be 
 not done, to caulk the seams with tow, and then varnish the 
 whole over. This will permit of its being cleaned by dry 
 scrubbing or sweeping, and, even if washed, of being quickly 
 dried. Too often, owing to the cracks and crevices in floors, the 
 enclosed space below, between it and the ceiling of the next room, 
 becomes a huge receptacle for dirt of all kinds. As already 
 explained, if the floor be a basement one, and unprotected by 
 concrete or other impermeable layer, or be over an unventilated 
 cellar, foul gases and air find a ready entrance into the room. 
 The necessity for the free ventilation of all closed spaces has been 
 explained, and nowhere is it more needed than in those below 
 basement floors. If the ventilation is insufficient, the air becomes 
 damp, and a fungus growth called dry rot is liable to set in and 
 destroy the flooring. In the upper storeys, however, the ventila- 
 tion through the boards and ceiling is usually sufficient, unless 
 constantly covered with oil-cloth or some other air-tight material. 
 The skirtings round rooms or floors should, when possible, be of 
 tiles or cement, but if of wood, they ought to be let into a groove 
 in the floor, a device which will serve to prevent draughts coming 
 through, and the accumulation of dust in the holes or cracks, 
 which are invariably formed by the shrinking of the joints and 
 skirtings. If floors were made better, so as to ensure a more or 
 less uniform and impervious surface without cracks, or badly 
 made joints, through which draughts can enter and dust collect, 
 there would be less inducement to cover the whole floor area 
 with a carpet or drugget as is so commonly done. If carpets are 
 used, they should be sufficiently limited in size as to leave a 
 border of bare flooring round the room. This arrangement does 
 not allow dust to accumulate readily in corners, and at the same 
 time simplifies the taking up and beating of the carpet. 
 
 In the chapter on " Ventilation " allusion has been made to the 
 various and best means of warming the dwelling. A few remarks 
 here may not be inappropriate, relating to gas-pipes, water-service 
 pipes, and hot-water supply arrangements. Very few houses now 
 
FLOORS. 223 
 
 are without a gas supply, simply because it is relatively both 
 cheaper and more convenient than lighting by candles or oil 
 lamps. Few people have a choice as to the source of their gas 
 supply. In general terms, it may be described as a mixture of 
 carburetted hydrogen with various other hydrocarbons distilled 
 from coal in retorts, and, after purification, delivered by public 
 companies to individual tenements. Every house supplied with 
 gas has a meter, or arrangement for measuring the amount 
 supplied. This meter should always be a dry one, as what are 
 called wet meters contain water, and this being liable to freeze in 
 cold weather, may cut the supply of gas off altogether. Owing to 
 gas being always stored in the gasometers over water, it readily 
 absorbs it, and rapidly deposits it again when reduced in tem- 
 perature. The result of this is, all gas tends to deposit moisture in 
 the pipes which deliver it. This naturally collects in the lowest 
 sections, and the gas can only get through it in bubbles, causing 
 the well-known flickering of the flame. During frost, this may 
 form a solid and impermeable obstruction. To obviate this, and 
 prevent water lodging, a small pipe should be connected with the 
 lowest part of the domestic service and fitted with a tap to draw 
 off any collection of water. Supervision is needed to see that 
 gas-pipes are not hidden in walls or behind woodwork, where 
 nails are liable to be driven in and puncture them. Care needs 
 to be taken to see that all joints and fittings do not leak, as any 
 such defects are a fruitful source of gas explosions, besides which 
 there is reason to believe that the escape of minute quantities of 
 gas from defective fittings, especially in bedrooms, often causes 
 headache, sore throat, and other conditions of ill-health. The 
 sliding gasaliers and pendants are all sealed with water-traps ; 
 these require to be systematically refilled to prevent their running 
 dry, and so allowing gas to escape. The placing of a little oil on 
 the top of the water after having filled the tube will commonly 
 prevent loss of water by evaporation. Too much care cannot be 
 given to the choice of a good burner; the relative value and 
 effect of some of them has already been referred to. 
 
 Dealing as this chapter does with the construction of the house 
 itself, it is not out of place to remark that the greatest care should 
 be taken to see that water-supply pipes are so placed as to be 
 protected from frost. All outside walls should be avoided if 
 possible ; if necessity compels pipes to be exposed, they should be 
 surrounded with casings of sawdust or wrapped up in felt. Branch 
 pipes should be as few and short as possible, and made to go off 
 at an acute angle in the direction of the flow. Cold water should 
 be available, and laid on to sinks in the kitchen and scullery, to 
 the bathroom — if such exist — also to the cistern for flushing 
 
224 SOILS, SITES, AND BUILDINGS. 
 
 closets, and in cases where no constant supply is laid on, to a 
 separate storage cistern. It is usually convenient when a house 
 is in connection with a public supply to have the water delivered 
 in the kitchen and scullery direct from the main ; a similar supply 
 from the main should, if possible, be delivered to the upper floors. 
 In the best houses now, all taps which deliver water from the mains 
 are marked " main," while those which yield water from cisterns 
 are marked "cistern." This detail ensures greater care in the 
 placing of fresh water in bedroom bottles, and avoids the issuing 
 indiscriminately of stored water, it may be rain water, from cisterns 
 for both washing and drinking purposes. Whenever possible the 
 use of storage cisterns for water should be avoided. Most water 
 companies take care to lay their supply pipes deep enough in the 
 soil (2 feet) to protect them from freezing; such pipes should be 
 fitted with a stopcock or valve for cutting off the water during 
 emergencies, such as leaks or frosts. Where pipes run horizontally, 
 care should be taken to see that they are laid on continuous 
 supports, and at a slope sufficient to run off their contained water 
 when it is required to empty them. When pipes run vertically 
 they are best fastened to wood rather than to masonry. 
 
 Hot-water Supplies. — The supply of hot water constitutes an 
 important feature in every dwelling, and various systems have 
 been suggested. The earliest form was the Ofie-pipe method which 
 consisted of a large iron boiler fixed in an open fireplace and 
 connected by a pipe to a cold-water cistern fixed above the 
 highest fitting to be supplied with hot water. On the introduc- 
 tion of small boilers with closed ranges, together with circulating 
 pipes and a hot-water reservoir of some kind for storing hot water, 
 the one-pipe method gave way to the tank system. The tank 
 system consists of a cold-water cistern and a hot-water tank fixed 
 above the highest fittings that are required to be supplied with 
 hot water, the boiler being placed usually behind the kitchen 
 range. There are various modifications of this system. In most 
 cases the flow-pipe is used also as the draw-off to the various 
 fittings, but this presents the disadvantage that if the cold-water 
 supply runs short the whole of the hot water in the cistern and 
 pipes may be drawn off, unconsciously, and lead to serious 
 results. To remedy this, another pipe taken from nearly the top 
 of the hot-water tank should be introduced to supply the draw- 
 ofts to the various fittings. 
 
 The next development was the cylinder system. In this (Fig. 
 30) the hot-water reservoir is placed below or nearly on a level 
 with the various fittings to be supplied with hot water, whereby, 
 hot water being drawn from the top of the cylinder, it cannot be 
 emptied and, should the cold-water supply to the cylinder fail, no 
 
HOT-WATER SUPPLIES. 
 
 225 
 
 hot water can be drawn from the taps. By this arrangement the 
 boiler, circulating pipes, and cylinder must remain full of water. 
 In the best types of this kind of hot-water installation, the cylinder 
 is fixed as close as possible to, and one or two feet above, the 
 boiler level. When fittings supplied with hot water are some 
 distance from the cylinder, 
 the hot water in long 
 lengths of pipe, being 
 stagnant, soon cools, and 
 annoyance is caused by 
 having to wait until the 
 cold water in the pipes is 
 run off before hot water 
 can be obtained. To over- 
 come this, a method known 
 as the cylinder system, with 
 secondary flow and return, 
 is often adopted ; it in- 
 volves simply the supply- 
 pipe being returned with a 
 slight fall direct to the 
 cylinder again, and from 
 this pipe a short branch 
 taken to supply the various 
 fittings with hot water. In 
 all cylinder systems, a pipe, 
 variously called the " ex- 
 pansion," "exhaust," or '• rising main," is taken from the top of 
 the cylinder vertically or obliquely, but never horizontally, and 
 terminates either through the roof or, preferably, over the cold- 
 water cistern. From this pipe all the hot-water taps are supplied. 
 As all the three foregoing arrangements present certain in- 
 conveniences, the combined or cyli?ider tank system has been 
 introduced. This arrangement (Fig. 31) consists of a boiler, the 
 cylinder, the hot-water tank, and the cold-water cistern. The 
 cylinder is fixed as close to the boiler as convenient, and the hot- 
 water tank above the highest fittings to be supplied. The cold- 
 water cistern is placed above the hot-water tank. In the example 
 drawn, the cold-water supply is taken direct from the cold-water 
 cistern to the cylinder ; the secondary flow and return pipes from 
 the cylinder to the hot-water tank enter at the bottom of the hot- 
 water tank, making this tank practically a circulating pipe of 
 enlarged proportions. With pipes arranged in this manner, baths, 
 lavatories, and sinks can be well supplied with hot water in all 
 parts of a house. 
 
 Fig. 30. — Cylinder system of domestic hot-water 
 supply. (After Bennett.) 
 
226 
 
 SOILS, SITES, AND BUILDINGS. 
 
 Although the cylinder tank system has the advantages of both 
 the tank and cylinder systems, the whole of the installation may 
 be spoiled if the two hot-water reservoirs are too large. It must 
 be borne in mind, also, that the amount of hot water supplied 
 
 depends not so much 
 on the particular 
 system adopted, but 
 on the size and effici- 
 ency of the boiler; 
 and it is much better 
 to have a boiler large 
 enough to do the 
 work comfortably 
 than to keep it and 
 the fire at high pres- 
 sure in order to be 
 able to supply an 
 average amount of 
 hot water. Another 
 point to be remem- 
 bered is that, while 
 domestic hot-water 
 supply systems may 
 under ordinary cir- 
 cumstances be con- 
 sidered safe, occa- 
 sions are liable to 
 occur which render 
 them quite the re- 
 
 £ 
 
 verse ; the actual 
 
 Frc 31. — Cylinder tank system of domestic 
 hot- vater supply. (After Bennett.) 
 
 catastrophe being a 
 kitchen boiler ex- 
 plosion. The cause of 
 these boiler explosions may be brought about in three different 
 ways : (1) By the incrustation of lime or rust deposits in tfye boiler ; 
 (2) by the use of stop-valves on the circulating pipes ; (3) by frost. 
 As a rule, the first cause is rare, as the deposit grows slowly and 
 in so doing closes up the bore of the pipe gradually \ synchronous 
 with this occlusion of the pipes there is a reduction of delivery of 
 water, and the occurrence of alarming noises which suggest an 
 examination of the apparatus before any actual harm is done. 
 The use of stop-valves is a more serious matter. These valves 
 are resorted to when two boilers are connected to one cylinder, 
 or where the house is supplied with water of high temporary 
 hardness, as conveniences to facilitate the periodic cleaning out 
 
WATER-CLOSETS. 227 
 
 of the boiler. If these valves are meddled with by persons who 
 do not understand their uses, or they are inadvertently left closed 
 when they should be open, the possibilities of the boiler being 
 exposed to a strain, from enclosed steam under a high pressure, 
 which it cannot withstand, are readily imagined. Frost is un- 
 doubtedly the chief cause of domestic boiler explosions, and it is 
 important that hot- water pipes should be protected from frost, or 
 the whole of the apparatus may become a source of great danger. 
 Should the expansion pipe become blocked with ice during a 
 severe frost or, from similar cause, any part of the circulation be 
 occluded, the only means of exit for the heated water and steam 
 in the boiler is sealed up. Quite unconscious of danger, the firing 
 of the boiler continues, with the result that the water has no room 
 to expand, and continuing to receive heat from the fire, it stores 
 up energy in proportion to the pressure on, and the quantity of 
 the water contained in, the boiler and pipes. Now the ordinary 
 type of kitchen boiler, not being constructed to withstand such an 
 enormous strain, it follows that it bursts. The best means of 
 obviating such a disaster is to fix a safety-valve either directly on 
 the boiler or on a pipe carried a short distance from the boiler 
 free from bends or angles. It must be fixed in an accessible 
 position, and in such manner as to prevent the deposition of soot 
 and dust on the safety-valve. 
 
 Another accident which may occur in these hot-water supply 
 installations is the collapse of the cylinder. This is rare, but 
 occurs usually as the result of frost causing an occlusion of the 
 outlet of the expansion pipe and also of the supply pipe to the 
 cylinder. As the fire cools down during the night, there is a 
 corresponding cooling and contraction of the boiler and cylinder 
 contents. If this continues, a partial vacuum forms in the cylinder, 
 followed by its collapse from external atmospheric pressure. The 
 only remedy is the placing of a valve on the cylinder to adjust 
 automatically the inner and outer pressures. 
 
 An important and integral part of the dwelling-house are the 
 arrangements needed to receive the excreta and refuse before they 
 pass into the proper channels of removal. These arrangements 
 usually comprise the ordinary water-closets, sinks and baths, slop- 
 closets, trough-closets, privies of various kinds, dry-earth closets, 
 ashpits, and dustbins. 
 
 Water-closets. — Each closet ought to have at least one window 
 of a minimum superficial area of two square feet opening direct 
 into the outer air, also have a second opening, such as either a 
 Tobin tube or a ventilating brick, so as to secure a circulation of 
 the air independently of the house. The closet walls ought to be 
 covered with glazed tiles, painted plaster, or varnished paper, the 
 
228 
 
 SOILS, SITES, AND BUILDINGS. 
 
 ceiling, too, ought to be varnished or painted. The floor may be 
 of tile or cement, or if of wood, well caulked and varnished. 
 
 The closet apparatus itself ought to be the simplest that can 
 be obtained consistent with efficiency, and as a rule it may be 
 stated that the more complicated the arrangement, the less likely 
 is it to be either efficient or perfect. The question of the precise 
 kind of closet to be adopted, whether on the water principle or on 
 some dry principle, is dependent mainly upon the special circum- 
 stances of the place. 
 
 Closets based upon a water system for the carrying away of 
 excrement are practically of three kinds, namely, (a) the ordinary 
 indoor water-closet as found in the majority of the better class 
 
 Fir,. 32.— "Valve " closet. 
 
 houses ; (b) slop-closets, or those in which the excrement is 
 washed away down the drain by the waste liquids of the house- 
 hold instead of by clean water supplied for that purpose; (c) 
 trough-closets, or those connected with a trough containing water, 
 and common to two or more seats, such as are met with in 
 schools, factories, and other places of common resort. The 
 essential features of a good type are, a basin of some non- 
 absorbent material and of such a shape and capacity as will 
 contain sufficient water to allow the excreta to fall direct into the 
 water in the basin without touching the sides, There may be said 
 to be three distinct types of water-closet now in general use ; they 
 are the valve closet^ the wash-out closet^ and the short hopper closet 
 or wash-down closet. 
 
WATER-CLOSETS. 
 
 229 
 
 The valve closet (Fig. 32) is still in considerable use, though 
 gradually being replaced by simpler types. Its chief faults are it 
 is somewhat complicated, the valve may leak or fail to keep a 
 sufficiency of water in the pan, and not infrequently it is difficult 
 to keep clean ; on the other hand, it offers a large water area, 
 and the basin seldom becomes foul. The overflow pipe should 
 always be trapped, and usually a special provision is made to 
 flush it. 
 
 Of the modern forms of water-closet, the wash-down or the 
 short hopper is in most general use. They are entirely made 
 out of a single piece of glazed earthenware, or at most of 
 two pieces cemented together, and present a minimum amount 
 of surface between the basin and the trap. In the wash-out 
 closet (Fig. 33), a certain amount of water is kept in the basin 
 
 Fig. 33. — "Wash-out" closet. 
 
 Fig. 34.—" Short hopper " closet 
 
 by means of a dam or ridge, over which the excreta are carried 
 by a flush of water. In some varieties of this closet, the ridge is 
 made too high, with the result that, unless the flush be good, the 
 contents are not at once carried away. It cannot be considered 
 as a satisfactory type of water-closet. Of the short hopper class 
 (Fig. 34), a good form is that represented by the " Deluge," which, 
 like all good closets, should be and is provided with a flushing 
 rim, from which the water flows in such a manner and direction 
 that the basin is kept constantly clean. The quantity of this 
 flushing water available should be at least 2 gallons, and to avoid 
 waste should not exceed 3^ gallons. It should be delivered by a 
 i^-inch pipe from a height of from 4 to 5 feet to secure sufficient 
 force for properly washing out the basin. In some modern types 
 of closet, the placing of the flushing cistern close to the level 
 of the top of the basin has been adopted with success. At first it 
 
2^0 
 
 SOILS, SITES AND BUILDINGS. 
 
 was thought that the cistern would not flush the basin and clear 
 out the trap so well as an elevated over-head cistern, but experi- 
 ence has shown this to be fallacious, as the provision of a i\ gallon 
 cistern and a larger inlet to the basin more than compensates for 
 the want of height. A great advantage of this arrangement 
 (Fig. 35) is that it is more silent in action than the ordinary water- 
 closet with cistern 
 fixed 5 to 6 feet 
 above the closet 
 basin. The flushing 
 water for closets 
 should be supplied 
 from a separate cis- 
 tern, and not from 
 a cistern or service 
 pipe which supplies 
 water for general 
 household pur- 
 poses. Numerous 
 instances are 
 known, showing 
 that outbreaks of 
 disease, such as sore 
 throats and enteric 
 fever, have resulted 
 from supplying 
 
 water-closets with 
 water direct from 
 mains or from cis- 
 terns common to 
 all needs of a 
 house, the special 
 danger or risk lying in the fact that foul air from the closet 
 basin tends to escape up the usually empty delivery pipe and be 
 absorbed by the water in the cistern. The cisterns for the 
 storage of water for closets are usually of iron, fitted with a ball- 
 cock and valve to regulate the admission of water from the main 
 supply, and provided with an overflow pipe. This overflow pipe 
 should discharge direct through the wall into the outer air a few 
 inches from the brickwork ; it should under no circumstances be 
 allowed to discharge into any pipe connected with closets. In 
 cases where water-closets are placed in the upper floors of houses, 
 a lead tray is frequently found placed beneath the apparatus to 
 prevent any overflow from the closet in case of leakage from 
 soaking into the floor and through the ceiling below. This tray 
 
 Fig. 35— The " Silent " closet (Shanks). 
 
WATER-CLOSETS. 
 
 23I 
 
 is commonly called a " safe," and is of course provided with a 
 waste or overflow pipe carried straight through the wall to end in 
 the open air, and in no way connected with any part of the 
 water-closet apparatus. The placing of a " safe " beneath a closet 
 was frequently needed when the closets used were the old pan 
 water-closets ; with the more modern and simpler arrangements the 
 need does not exist, while, too, the old custom of boxing in the 
 apparatus by means of wood- 
 work is now regarded as un- 
 necessary and more or less 
 uncleanly. 
 
 A recent development is 
 the siphonic action water- 
 closet, as shown in Fig. 36. 
 In it the service pipe from the 
 cistern has two connections to 
 the closet, one to the basin 
 in the usual manner, the other 
 to the top of the long leg of 
 the siphon, The flush is then 
 divided into two streams, one 
 of which flushes the basin, the 
 other rushes down the siphon, 
 expelling the air through the 
 puff-pipe ; this starts the 
 siphonic action, and empties 
 the basin, which is refilled 
 with clean water by an 
 after-flush arrangement in the 
 cistern. Closets of this type 
 are simple and efficient, free 
 from mechanism, automatic 
 
 ^^BBMZMMSS^ 
 
 Fig. 36. - " Siphonic " closet (Jennings). 
 
 in action, and provided with a good depth of water-seal. 
 
 The contents of a water-closet should be at once conveyed 
 by a suitable pipe called a soil-pipe, not less than 4 inches 
 in diameter, in as direct a manner possible through the house 
 wall to the outside. To prevent air or gas returning into 
 the house from the soil-pipe, and to completely disconnect it as 
 far as possible, it is essential that the closet basin should be 
 trapped. In case of the wash-down closet, the apparatus itself 
 contains the trap, but valve closets must have a trap specially 
 provided at the outlet. The essential point about this artifice is 
 that the bend be sufficiently great as to place some portion of the 
 " dip " of the pipe below the water-level, and the difference between 
 the water-level and the dip constitutes the seal of the trap ; to be 
 
232 SOILS, SITES, AND BUILDINGS. 
 
 at all effectual, a water-seal in a trap should be not less than ij 
 inches deep. Though there are various other forms of traps, 
 as will be seen later, practically the most useful form in con- 
 nection with water-closets are the P or S siphon-trap, so-called 
 from their shape. Now, like traps in other situations, those 
 belonging to water-closets are liable to become unsealed by a 
 great rush or volume of water passing into them, and emptying 
 them of their safety water by what is known as impetus action. 
 They are also liable to be unsealed by a sudden rush of water 
 passing their outlet. This is particularly liable to take place 
 when two or more water-closets discharge into the same soil-pipe, 
 with the result that the discharge from one sucks out water from 
 the traps of the others. This accident can be best prevented by 
 placing an anti-siphon vent in the crown or top of the trap, as 
 shown in Fig. 34, and particularly in the case of a series of water- 
 closets ranged one above another, and discharging into the same 
 soil-pipe, by causing the ventilating pipe or vent from the trap of 
 the lowest water-closet to join or receive, as it were, the ventilat- 
 ing pipe of each trap above, and the whole to be finally connected 
 with the soil-pipe above the highest closet. 
 
 The various conduits or pipes within a house, and which run 
 from either sinks or closets to the drain outside the house, are 
 conveniently called " house-pipes." These house-pipes are made 
 of either iron, lead, or of earthenware ; those made of cast iron 
 are the best, and should be so laid that an inspection of them 
 can be easily made. A pipe conveying house refuse or sewage 
 should not be allowed to pass under a building unless no other 
 means of construction is possible ; in which case it should be of 
 iron piping laid in as direct and straight a line as can be obtained, 
 moreover be supported on concrete laid at a depth below the 
 surface at least equal to its own diameter, and finally ventilated 
 at its upper end. Some builders are extremely anxious to conceal 
 pipes, particularly inside walls and under floors ; such methods are 
 not only bad, but very risky in case of leakage ; in all cases it is 
 infinitely better to run pipes at once by the nearest way through 
 the wall to the outside of the house, where it can join the proper 
 drain. 
 
 Baths. — The majority of houses now built for the upper and 
 artizan classes contain baths and bath-rooms. No bath-room should 
 open out of bedrooms unless used exclusively by that bedroom's 
 occupants. The best place for a bath-room is at the side of the 
 house, so that its waste water can be readily carried away outside. 
 The custom of placing a closet in a bath-room is bad, as it not 
 only makes the water-closet useless to the rest of the household 
 when the bath is occupied, but it further causes the bather to 
 
SINKS— SLOP-CLOSETS. 233 
 
 breathe foul air caused by any imperfection existing in the closet 
 fittings or by the use of the closet. Like closets, bath-rooms need 
 to be well ventilated, and their walls and floors covered with some 
 impervious material ; for these floors ordinary oil cloth or linoleum 
 is as good as anything. 
 
 Sinks. — Although the shape and material of which a sink is 
 made are not of great moment, still the construction and destination 
 of its water pipe are of importance. Formerly the plan was simply 
 to carry all sink-pipes directly into the soil-pipe. The consequence 
 was that foul smells and gases often came up through them, 
 rendering houses both offensive and unhealthy. It is now 
 recognized that the only proper and safe plan is to take care that 
 no pipes whatever join the drain except the soil-pipe of the water- 
 closet and housemaid's slop sink. All other pipes carrying slop 
 or waste water ought to deliver freely into the open air over the 
 trap leading to the drain. All sink pipes need to be provided with 
 a trap on their waste pipes, immediately beneath the sink, to prevent 
 polluted air from passing up the pipe from its open end (Fig. 44). 
 The common bell-trap, so often met with in sinks, is really of little 
 use as its loose top is liable to be removed (Fig. 47). 
 
 Slop-Closets. — In some towns, particularly in Lancashire and 
 Yorkshire, where a sufficient water supply is not available, or 
 precluded by financial reasons from being ultilized for flushing 
 and washing out water-closets, advantage is taken of the house- 
 hold waste water to do this necessary cleansing. Closets from 
 which the contents are removed by the slops or refuse liquids of 
 the household, instead of by clean water supplied for that 
 purpose, are called slop-closets. Of these there are two kinds, 
 namely, those in which the waste is allowed to run directly into 
 the basin, or is poured down by hand ; and those in which, with 
 a view to give a better flush, the waste liquid is held up or 
 collected in a suitable contrivance, and then discharged from 
 time to time in a sudden forcible stream ; these latter are dis- 
 tinguished by the name of " automatic slop-closets." The objection 
 to these closets is that the force or stream of water is often in- 
 sufficient to keep them clean ; also the closet basin is apt to get 
 fouled at the back and sides by excrement falling against it, 
 besides which improper substances are readily thrown down it 
 and block the pipes. To get these closets to work well, a good 
 fall to the sewer is necessary. 
 
 Another form of slop-closet, is that is which either a siphon 
 cistern, or tipper is used to collect the slop-water, and then 
 discharge it in a sudden flush. Experience indicates that the 
 tipper is preferable to the siphon tank, as the latter often will 
 not act owing to clogging with greasy water. A number of closets 
 
234 
 
 SOILS, SITES, AND BUILDINGS. 
 
 can be placed on one drain, a single trap serving for the whole 
 this being placed at the bottom of a manhole for convenience of 
 access ; a ventilation shaft is provided at the upper end. 
 
 The tipper is merely a metal or earth en ware vessel, so shaped and 
 balanced on pivots that when full the weight of the contained liquid 
 overbalances it, and causes its contents to be suddenly poured down 
 the pipe (Fig. 37). There are several varieties of these automatic 
 slop-closets ; in some the tipper is placed close to the sink discharge- 
 pipe (top-flushing), in others the tipper is placed well away from 
 
 Fig. 37.—" Duckett's " slop-closet. 
 
 the slop-stone, and more or less in a piece with the lowest section of 
 the closet-shaft (bottom flushing). The device as to these closets 
 is mainly a question of suitability to any particular place. The 
 tippers, to be effectual, must contain at least three gallons of 
 water tor single closets, and five gallons if flushing two or more 
 closets in a row. Some kinds do not have a self-acting tipper, 
 but one discharged by pulling up a handle. Others have the 
 tipper situated at the side or back of the closet-basin. The 
 various automatic slop-closets appear to be advantageous in that 
 their original cost is small, they consume less water, produce less 
 sewage, and, too, are less apt to either freeze or get out of order 
 than the ordinary water-closets ; against them are the facts that 
 they are unsightly, less cleanly than water-closets, owing to fouling 
 and lodgment of excreta on the sides. Their use can only be 
 recommended out-of-doors, and when the sewers have a good fall 
 and a public service of water is laid on to each house. It is also 
 important that each house should have a separate closet. Subject 
 

 TROUGH-CLOSETS — MIDDENS. 235 
 
 to these conditions, these slop-closets may be of great use and 
 value in towns and suburbs, especially when it is desirable to 
 economize the water. 
 
 Trough-Closets are those in which a long earthenware trough 
 filled with water passes beneath the seats of a number of closets 
 placed side by side, and receives the excreta from them. From 
 time to time these troughs are Hushed out by the discharge of a 
 volume of water either by an attendant, or automatically by a 
 siphon-cistern or tilting receiver, and the contents carried away to 
 the sewer through a trap at the end of the trough. These closets 
 are adapted for factories, and groups of artisans' houses, being 
 little liable to get damaged by rough usage or get out of order : 
 the only desideratum being a good large drain well jointed with 
 cement, and plenty of water. Their drawbacks are, original costs, 
 the large quantity of water used, and the alarming noise and 
 splashing which results if the flushing happens to take place when 
 the seat is in use. Trough-closets, whether automatic or other- 
 wise, can only be used where good drains exist and a supply of 
 water is laid on. They are most unsuitable for schools. 
 
 Middens. — In places where no facilities exist for the use of 
 any of the various kinds of water-closets, recourse has to be had to 
 some dry method of dealing with excreta from the house. This 
 embraces such arrangements as middens, or privies, and pail- 
 closets, whether used with ashes, charcoal, or earth. The institu- 
 tion of middens, or the setting aside of some spot for depositing 
 filth and refuse, though a most objectionable and insanitary arrange- 
 ment, was probably a great advance on the more primitive method 
 of depositing everything anyhow and anywhere. Objectionable as 
 they are, it is unfortunately a fact that middens or privies in some 
 form or other exist still, not only in rural districts, but in certain 
 towns, the essential principle in all being an attempt to both dry 
 and deodorize excreta and refuse by an admixture with ashes. The 
 original midden, if not a heap of decomposing filth, was at best 
 but a hole dug in the ground more or less full of rotting matter, 
 and giving rise to most offensive gases and liquids, which only 
 too readily polluted both the soil around houses and the wells 
 near them. In the present day, where middens do remain, their 
 existence is subject to certain definite rules and conditions ; these 
 are briefly as follows. The midden or privy must be at least 6 
 feet away from any dwelling, and 50 feet away from any well, 
 spring, or stream ; ready means of access must be provided for 
 the scavenger, so that the contents need not be carried through a 
 dwelling ; the privy must be roofed to keep out the rain, and be 
 provided with ventilating apertures as near the top as possible ; 
 that part of the floor which is not under the seat must not be less 
 
236 SOILS, SITES, AND BUILDINGS. 
 
 than 6 inches above the level of the adjoining ground, and 
 moreover be flagged or paved with hard tiles having an inclina- 
 tion towards the door of the privy of one-half inch to the foot, so 
 that liquids spilt upon it may run down outside, and not find 
 their way into the receptacle under the seat ; the size or capacity 
 of this receptacle may not exceed 8 cubic feet, by which 
 limitation a weekly removal of .its contents is necessitated; the 
 sides and floor of this receptacle must be of some impermeable 
 material, the floor being at least 3 inches above the adjoining 
 ground-level ; the seat of the privy should be hinged so as to 
 allow of the ashes being readily thrown in, and the receptacle 
 unconnected with any drain or sewer. Constructed and maintained 
 under these conditions, it is probable that the risks of fouling 
 either soils or wells are reduced considerably ; while the pollution 
 of the air is safeguarded to a large degree by the maintenance 
 of the contents in a dry and inodorous condition. But depending 
 as does the success of these middens upon sanitary supervision 
 and scavenging, it is universally acknowledged that any form of 
 them is unadvisable, no matter how well constructed and super- 
 vised. 
 
 The various forms of Tub and Pail Closets are really nothing 
 more than miniature middens, in which the ashpit is represented 
 by a movable receptacle, such as tub or pail, placed under the seat 
 for the reception of the excreta. It is claimed for these closets 
 that the filth removal is much easier and the air pollution less than 
 when midden contents are removed. The pails, whether of wood or 
 of galvanized iron, should have close-fitting lids as nearly air-tight 
 and water-tight as possible, to be placed on the pail when removed 
 for emptying. The structure of the closet in which pails are used 
 should be similar to that proposed for middens. The pail or tub 
 should be removed not less often than once a week, and a clean one 
 substituted for it. To avoid unhealthy smells it is most important 
 that the contents of the pails (urine and faeces) should be kept as dry 
 as possible. This can only be effected by adding to the contents 
 some dry and absorbent material such as ashes, charcoal, earth, or 
 even lining the pail with some absorbent substance such as sawdust 
 or peat. If the mixed urine and faeces be left to themselves in the 
 pails, they rapidly undergo decomposition, but in this state they 
 have a higher commercial value as manure than if mixed with ashes, 
 charcoal, or earth. Various modifications in this respect are in 
 use in various towns ; thus in some not only ashes, but all other 
 household refuse is added to the pail, while in others the pails 
 only receive excreta. The presence of the urine tends much to 
 increase decomposition, but its separation is not only practi- 
 cally difficult, but an actual loss of fertilizing material if intended 
 
 
TUB AND PAIL CLOSETS. 237 
 
 for manure. In Manchester only the fine ashes after sifting 
 are allowed to fall into the pails; while in Halifax, what is 
 called the Goux system was at one time in use, the pail 
 being lined with a layer of peat, or a mixture of tan, sawdust, 
 and soot, substances which render the contents drier and less 
 offensive. Sifted house cinders and ashes form very efficient 
 deodorizers and desiccators, and being always found on the 
 premises of any house are more readily usable than either char- 
 coal or earth. Both these latter substances are also used in 
 pail-closets. In Stanford's closet the charcoal used is prepared 
 from seaweed, about | lb. being used each time. Neither ashes 
 nor charcoal have the same beneficial and disintegrating action 
 on the excreta that dry earth has. For this reason, earth-closets 
 have had in one place and another a very extensive trial. About 
 1 \ lb. of clean dry earth is thrown upon the pail contents, either 
 automatically from a hopper, or by hand every time the closet is 
 used. The best kinds of earth for the purpose are loamy surface 
 soil, vegetable mould, dry clay, or brick earth. Chalk, gravel, 
 and sand are not suitable. Care has to be taken that the earth 
 stored is sifted and dry, and that each particular stool is covered 
 at once with the earth, and no slop- water added to the pail 
 contents. Earth-closets are practically the only form of closet 
 used throughout the whole of India, where, on the whole, they 
 work extremely well. If a pail-closet is going to be used at all, 
 from a sanitary point of view the earth-closet is the best form, as, 
 if properly managed, the closet is free from smell, and the process 
 of removing the contents not offensive. In addition to this, the 
 earth is readily obtainable, and not without value as an applica- 
 tion to both fields and gardens. 
 
 As regards any question which might arise as to which kind 
 of closet should be placed in any particular house or group of 
 houses, the answer would depend entirely upon the circumstances 
 of the case. Middens, being contrary to all sound principles of 
 hygiene, should in no case be adopted when facilities exist for 
 any other arrangement. For the better class of houses, water- 
 closets or earth-closets are best suited in the country, and water- 
 closets alone in towns. For houses occupied by the artisan class 
 in towns, it is probable that slop water-closets are preferable to 
 pail-closets. The experience of towns where these latter have 
 been in long use goes to show that they are expensive to work, 
 and that the ashes and other dry refuse are so difficult to dispose 
 of as manure, that much of them has to be got rid of by burning 
 in destructor furnaces, a process which the presence of excrement 
 renders more difficult. These are circumstances which render it 
 desirable to separate, as far as possible, the excrement from the 
 
238 SOILS, SITES, AND BUILDINGS. 
 
 solid refuse of the town, and remove it rapidly by the increased 
 facilities afforded by the now very general development and 
 maintenance of public water supplies and sewers. 
 
 In towns and places where either water-closets in some form 
 or other, or pail-closets for excreta alone, are in use, arrangements 
 must be made for the removal of ashes and kitchen refuse separ- 
 ately. Inasmuch as these can only be removed at intervals from 
 the houses where they accumulate, it is important that they be so 
 stored as to remain free from offence while still on the premises. 
 The articles most likely to become offensive are organic matters, 
 particularly kitchen refuse. In all properly conducted households, 
 these are invariably burnt in the kitchen fire, while only the 
 indestructible matter is placed with the dust and ashes. This 
 practice should be invariably carried out in all dwellings and 
 families. Formerly, the receptacles for ashes and house refuse 
 were dust-bins constructed of brickwork, leaning upon a yard- 
 wall, or against the side of the house, with a wooden cover and a 
 door at the side or front for the removal of contents. This faulty 
 arrangement rendered the contents of the dust-bin extremely 
 liable to become wet from rain, resulting in steady decomposition 
 of the organic refuse with the production of much offensive gas 
 and smell. So glaring were the defects of this system that it has 
 become largely replaced by the provision to each house of small 
 covered tubs or galvanized iron pails or boxes placed in an out- 
 house or yard, and regularly emptied at short intervals. In some 
 places, especially for large establishments, large water-tight bins 
 or so-called dry ashpits are used, the contents being removed at 
 less frequent intervals. 
 
 The more detailed account of the ultimate disposal of the 
 contents of water-closets, pail-closets, and dust-bins is given in 
 the succeeding chapter. 
 
 Schools. — It is a remarkable fact that, up to within the last 
 few years, the hygiene of schools and school-houses has ceceived 
 but a small amount of attention. The general principles laid down 
 in the preceding pages as to site, surroundings, construction, and 
 drainage of ordinary dwelling-houses, apply equally to schools. 
 Schools may roughly be divided into three great groups : (1) 
 those under State or public control, such as Elementary Schools 
 and those in Poor-law institutions ; (2) the large residential schools 
 and colleges for the upper, middle, and lower classes throughout 
 the country, usually under the control of nominated or elected 
 governors; (3) private schools or colleges, more or less con- 
 ducted by irresponsible teachers or proprietors. In regard to 
 the schools included within the first two groups, considerable 
 supervision is exercised with reference to questions concerning 
 
SCHOOLS. 239 
 
 the health of the scholars as a result of the actions of officials 
 of the Board of Education, Municipal Corporations, County 
 Councils, the Ministry of Health, and the Association of Medical 
 Officers of Schools. But, in the case of the purely private 
 schools, there practically exists no controlling authority as to their 
 arrangements and construction. The chief hygienic defect in the 
 arrangement of all schools appears to consist in the undue aggre- 
 gation of the children. Oddly enough, this is notably so in 
 those schools which come under the inspection of the State, or 
 in respect of which there is a grant of money calculated upon 
 the number of children and the degree of education attained. 
 This tendency to overcrowding in schools lowers the general 
 health standard of the scholars, fosters any liability to disease 
 that may exist in the individual children, and, at the same time, 
 promotes the spread of any communicable or infectious complaint 
 that may be introduced among them. 
 
 For planning and fitting new buildings for elementary schools, 
 the Board of Education are of opinion that, for large schools 
 accommodating from 300 to 500 places, the most suitable plan 
 is that of a central hall with from seven to ten class-rooms 
 grouped round it. For small schools, a schoolroom with one or 
 more class-rooms will be sufficient, but there should be always at 
 least one class-room, except in special cases. Where the site is 
 sufficiently large, open, and fairly level, the most economical plan 
 is that in which all the rooms are on the ground floor, but circum- 
 stances may compel the building to have three floors, but it is 
 desirable that a public elementary school should be on not more 
 than two floors. When there is a central hall it should have a 
 floor-space of not more than 4 square feet for each scholar for 
 whom the school is recognized. The hall must be fully lighted, 
 warmed, and ventilated. Large schools not built with a central 
 hall must be provided with a wide corridor from 8 to 12 feet 
 wide, giving access to the rooms. The site area may be taken 
 to average a quarter of an acre for every 250 children. 
 
 Where a schoolroom is the principal room in a school which 
 has neither central hall nor corridor, it should never be designed 
 for more than 100 children. No schoolroom is ideal which is 
 lighted from one side only, but frequently it is the only possible 
 way. When a school consists of a single room, that room should 
 not contain more than 600 square feet of floor-space. The 
 class-rooms should not be passage-rooms from one part of the 
 building to another, nor from the schoolroom to the play-yard. 
 As a rule, class-rooms should not be planned to accommodate 
 more than 60 nor less than 24 children. In the absence of sup- 
 plementary light the measurement from the window-wall in a 
 
240 SOILS, SITES, AND BUILDINGS. 
 
 room 14 feet high should not exceed 24 feet 8 inches. When a 
 building is for the use of older scholars, the schoolroom and 
 class-rooms must show an average of not less than 10 square 
 feet of floor-space for each place proposed to be provided; 
 in infant schools, an average of not less than 9 square feet for 
 each place may be accepted. In the higher elementary schools 
 a minimum of 12 square feet per scholar is requisite. In no 
 case should a central hall or corridor be included as counting 
 towards the accommodation available in an elementary public 
 school. 
 
 The seats and desks provided in schools should be graduated 
 according to the ages of the scholars, fitted with backs and placed 
 at right angles to the window- wall. An allowance of 18 inches 
 per scholar at each desk and seat will suffice (except in the case 
 of the dual desk), and the length of each group should be there- 
 fore some multiple of 18 inches, with gangways of 18 inches 
 between the groups and walls. In the case of the dual desk the 
 usual length is 40 inches, and the gangways 16 inches. In an 
 ordinary class-room five rows of long desks or six rows of dual 
 desks are best, but in rooms providing for more than 60 children, 
 there should not be more than four rows of long desks or five 
 rows of dual desks. Each desk should be inclined at an angle 
 of 15 degrees. Flat desks tend to make children stoop; the 
 edge of the desk, when used for writing, should be vertically over 
 the edge of the seat. 
 
 The wall of every room used for teaching must be at least 
 12 feet high from the floor to the ceiling; if the room-area exceed 
 360 square feet, the height should be 13 feet; and, if it exceed 
 600 square feet, then the height of the walls must be at least 
 14 feet. Roofs open to the apex are undesirable in schools. 
 The outer walls of all schools should be solid ; if of brick, the 
 thickness must be at least one brick and a half, and, if of stone, 
 at least 20 inches; where hollow walls are preferred, the external 
 one must be 9 inches thick, with a 4^-inch lining and a 2-inch 
 cavity. All walls should have a damp-proof course just above 
 the ground-line, and all timber be protected from mortar and 
 cement by asphalt or tar. In all schools, entrances should be 
 separate for each department and each sex, the doors opening 
 outwards as well as inwards. Each department in a school should 
 have its own staircases, separate ones being provided for boys and 
 girls : these staircases should be fireproof, and external to the 
 halls, corridors, or rooms. Triangular or winding stairs are 
 objectionable, each step should be about 13 inches broad and 
 not more than 6 inches high. The provision of proper cloak- 
 rooms in schools is of importance; these should be external to 
 
SCHOOLS. 241 
 
 the schoolrooms and class-rooms, also amply lighted and venti- 
 lated, and providing separate ingress and egress. The gangways 
 between the hanging-rails should be 4 feet wide, the hat-pegs 
 12 inches apart, not directly one above the other, numbered, and 
 of two tiers. The lighting of school and class rooms is of vital 
 importance. Where left light is impossible, right light is next 
 best; windows full in the eyes of scholars are objectionable. 
 The sills of the main lighting windows should be placed not more 
 than 3 feet above the floor ; the windows should reach nearly to 
 the ceiling, and the upper portion be made to swing inwards. 
 Skylights are particularly objectionable. The ventilation and 
 warming of rooms used for teaching are of paramount importance. 
 There must be ample provision for the continuous inflow of fresh 
 air and for the outflow of foul air. The best way of providing 
 the latter is to build to each room a separate air-chimney, carried 
 up in the same stack with the smoke-flues. An outlet should be 
 by a warm flue or exhaust, otherwise it will often act as a cold 
 inlet. Inlets are best placed in corners of rooms furthest from 
 doors and fireplaces, and should be arranged to discharge upwards 
 into the room. Gratings in floors should never be provided. The 
 ideal temperature for a school or class room is from 56 to 60 
 degrees. Where possible, this warming should be secured either 
 by means of open fireplaces or by hot-water pipes. Common 
 closed stoves are most undesirable, and should be permitted only 
 when provided with proper chimneys, of such a pattern that they 
 cannot become red hot, are supplied with fresh air, direct from 
 the outside by a flue of not less than 72 inches, superficial, and of 
 such a size or shape as not to interfere with the floor-space 
 necessary for teaching purposes. All fireplaces and stoves need 
 to be protected by guards. As regards sanitary arrangements in 
 schools, water-closets within the main building are not desirable. 
 They should be at a short distance and completely disconnected 
 from the school. Privies should be fully 20 feet distant. 
 Approaches to all latrines, urinals, or closets must be wholly 
 separate for boys and girls. Every closet should be at least 27 
 inches wide, fully lighted, ventilated, and supplied with a door 
 3 inches short at bottom and 6 inches short at top. More than 
 one seat should never be allowed in any closet. The following 
 table shows approximately the number of closets needed in 
 schools : — 
 
242 
 
 SOILS, SITES, AND BUILDINGS. 
 
 
 For girls. 
 
 For boys. 
 
 For infants. 
 
 For girls 
 and infants. 
 
 Under 30 children. 
 
 2 
 
 I 
 
 2 
 
 2 
 
 ,, 70 ,, ... 
 
 4 
 
 2 
 
 3 
 
 4 
 
 ,,100 ,, . . . 
 
 5 
 
 n 
 
 3 
 
 4 
 
 5 
 
 ,, 150 ,, . . . 
 
 6 
 
 ^ 
 
 
 
 5 
 
 6 
 
 ,, 200 ,, ... 
 
 8 
 
 4 
 
 6 
 
 7 
 
 »> 3°o >» ... 
 
 12 
 
 5 
 
 8 
 
 8 
 
 In boys' schools the urinal accommodation should be in the 
 proportion of 10 feet per 100 boys. Earth or ash closets, if of 
 an approved type, may be employed in rural schools, but drains 
 for the disposal of slop and surface water are necessary. Cesspits 
 and privies should be permitted only where unavoidable ; these 
 should be at least 20 feet from the school. 
 
 The whole scheme of the school premises should be to provide 
 the best possible hygienic environment for the scholars and present 
 an object lesson of cleanliness, good taste, brightness, and a 
 scrupulous regard for all sanitary demands. At the end of the 
 school day the doors and windows should be opened and the 
 floors of all class-rooms, cloakrooms, and corridors swept and 
 cleaned. Cleaning is best done by means of dustless oils, this is 
 particularly so in the case of floors. At least once a month all 
 woodwork should be scrubbed and all cupboards, bookcases and 
 storerooms cleaned out. At the same time maps, books, etc., 
 should be taken outside the buildings, shaken and well dusted. 
 
 Hospitals. — All that has been said in respect of site, surround- 
 ings, and construction of houses and schools applies with still 
 greater force to hospitals. As charitable institutions, existing 
 for the purpose of affording medical and surgical aid to the sick 
 poor, hospitals, on economical grounds, have largely to be so 
 constructed that the patients may be grouped together in general 
 wards. It is this aggregating of large numbers of sick or diseased 
 persons under one building that constitutes the most important 
 factor in hospital hygiene. It has long been known that over* 
 crowding in the wards of hospitals is productive of the worst 
 results, particularly in surgical wards, where the neglect of proper 
 sanitary measures produces the class of diseases known as "septic," 
 of which well-known forms are erysipelas and blood-poisoning. 
 Bearing this fact in mind, we are able to understand that the 
 chief conditions to be avoided in all hospitals are : (1) insuffi- 
 ciency of cubic space ; (2) inefficient ventilation ; (3) improper 
 arrangements for the removal of excreta, refuse, soiled linen, 
 dressings, poultices, etc. ; (4) faulty arrangements of the buildings. 
 
 
HOSPITALS. 2z}3 
 
 Insufficiency of cubic space and inefficiency of ventilation go 
 together j in fact, mere cubic space of itself is of little value, 
 unless accompanied by adequate ventilation. As a general rule, 
 it may be said that large wards are more readily ventilated, 
 warmed, and managed than small ones. The most general form 
 of hospital wards is rectangular ; but in a few hospitals they are 
 circular. For circular wards, the following advantages have been 
 claimed: (1) freedom of frontage to all points of the compass, 
 and, consequently, greater accessibility to both light and air ; (2) 
 greater area contained within a given length of wall ; (3) greater 
 facilities for administration and cleanliness. They certainly have 
 some advantages and exist in several hospitals, but they have the 
 defect of being expensive to build. For general hospitals, the 
 common form of ward is rectangular being usually 120 feet long 
 and 25 feet wide with a height of 12 feet. This for thirty patients 
 gives to each 1200 cubic feet of space and 100 square feet of floor 
 space. For infectious disease hospitals the minimum floor space 
 should be 144 square feet and 2000 cubic feet of space, the 
 window surface being 1 square foot for every 60 feet of cubic space. 
 Experience shows that in general hospitals nursing is best carried 
 out when the number of beds in a ward do not exceed thirty or 
 thirty-two. These beds are best arranged with their heads to the 
 wall and facing into the ward. Each bed should be placed 
 between two windows, or, at most, two beds in between two 
 windows The windows ought to be opposite one another, and 
 should extend from 3 feet above the floor to witnin 6 inches of 
 the ceiling ; they should all be capable of being opened at their 
 upper parts. One square foot of window may be provided for 
 every 80 cubic feet of space in the ward. The heating of hospital 
 wards may be effected by open fireplaces or ventilating stoves, or 
 both, or by hot-water pipes. The temperature of wards is best 
 kept at 6o° F. To secure adequate ventilation, the air is best 
 warmed before passing into the wards. This may be done either 
 by means of ventilating stoves, Galton's grates, or by coils of hot 
 pipes at inlets placed beneath the heads of the beds. Extraction 
 of foul air is provided by fireplaces, stoves, windows open at the 
 top, or by special shafts. In some infectious hospitals, such ex- 
 traction shafts are made to lead to a furnace, the heat of which 
 serves both as a means of extraction and a means of destroying 
 any germs which may be in the outgoing air. It is needless, 
 perhaps, to say that the floors should be impervious, free from 
 crevices, and polished ; the walls ought to be lined with tiles, 
 cement, or glazed brick j or, failing these materials, simply 
 painted. The junction of floor and the walls may be made 
 round, so that dust can be easily seen and removed. 
 
244 SOILS, SITES, AND BUILDINGS. 
 
 As regards the faulty arrangement of hospital buildings, the 
 chief defect usually met with is the absence of effective separation 
 of the wards from the other parts, with due regard to economy 
 of construction. The precise disposition of the several parts of 
 a hospital in relation to each other, of necessity greatly depends 
 on the size of the hospital and on the shape and area of the site ; 
 but the really essential principles which should guide us in con- 
 structing a hospital are, briefly : (i) an avoidance of all intimate 
 connection between the wards and the administration buildings ; 
 (2) separation of medical from surgical wards ; (3) complete 
 atmospheric disconnection between the wards on the one hand, 
 and the mortuary, laundry, and out-patient department on the 
 other (Keith Young). 
 
 To secure these results, the most common plan now is to 
 build hospitals upon what is called the pavilion system. This 
 system is merely the arranging, on a plot of ground, of a series 
 of one, two, or more storey buildings, called pavilions, and con- 
 necting them together by corridors or covered ways. The indi- 
 vidual pavilions or blocks of buildings may be of any shape or 
 size, as, for instance, in the Great Northern Central Hospital, 
 London, where, although there are both circular and oblong 
 wards, they are all practically isolated from each other and from 
 the rest of the hospital. Care should be taken to see that the 
 various buildings are not so close to each other as to seriously 
 interfere with the free circulation of air, or shut out light. A 
 good rule to adopt is, if of two buildings one is higher than the 
 other, the distance between them must be equal to the height of 
 the higher ; if two buildings are of the same height, then the 
 distance must be one-and-a-half times the height. 
 
 Besides ordinary or General Hospitals, there are a number 
 of what may be called Special Hospitals. Among these latter 
 are such hospitals as those for diseases of the eye, ear, or throat ; 
 those for consumption, for children, for convalescents, for cancer 
 or incurables, for lying-in wcmen, and, finally, those for infectious 
 diseases. Although in all matters of structural hygiene these 
 hospitals require the same care as the ordinary hospitals, still, in 
 addition, they present some special needs. Thus, ophthalmic 
 hospitals need the removal of sharp angles in wards against which 
 blind or partially blind persons may accidentally injure them- 
 selves, and the provision of handrails on both sides of staircases. 
 Open fireplaces are a mistake in these hospitals, as often the 
 flickering flame of a fire is both trying and injurious to the eyes. 
 
 Hospitals for tuberculosis cases require special ventilation 
 arrangements. Many of these are now constructed on the open- 
 air system where one side of the ward can be opened out, thus 
 
HOSPITALS. 245 
 
 making one side of the ward open to the air. These wards need 
 only 80 superficial feet of floor area per bed and only 800 cubic 
 feet per bed. The general results of this system have been good. 
 
 For children's hospitals the most prominent need is one or 
 more isolation wards, as young children are extremely susceptible 
 to infectious diseases. Convalescent hospitals are more properly 
 homes for those recovering from acute illness, rather than mere 
 hospitals for the sick. In the same way, cancer and incurable 
 hospitals need to conform more to the freedom and independence 
 of home life than to the more rigid arrangements of the institutions 
 for treating acute cases. Lying-in hospitals, from the peculiar 
 nature of the cases they receive, should be constructed with small 
 rooms and not with large wards. Every such hospital should be 
 provided with an isolation ward, absolutely distinct from the rest 
 of the building. 
 
 Isolation, or infectious hospitals, are quite a class by them- 
 selves ; they may be either permanent or temporary buildings. 
 Reference has already been made to the need, in these hospitals, 
 of greater cubic space and ventilation. Owing to the remarkable 
 tendency to the spread of infection in the diseases taken to 
 infectious hospitals, the communication with the outside world 
 has here to be kept under the strictest control and each disease 
 isolated separately, and kept, if possible, in separate blocks or 
 buildings, the communication between which should be absolutely 
 forbidden. Each block, besides wards, closets, bathrooms, and 
 sinks, should have linen, store, and fuel rooms, as w r ell as a nurse's 
 room. The disinfecting chamber, mortuary, and stables for am- 
 bulances and horses, should also be clearly disconnected from all 
 other parts of the building. 
 
 Modern practice favours the provision of small wards in fever 
 hospitals, as such wards reduce the risk of secondary infections, 
 and facilitate the classification of patients both as to severity and 
 stage of the disease. Also some success is reported by the cubicle 
 system combined w T ith aseptic nursing. Much appears to depend 
 on the nurse under this system and how well she conforms to 
 asepsis and the careful washing of her hands, changing her over- 
 all and other details before passing from one patient to another. 
 
 Considerable controversy has taken place whether infectious 
 or isolation hospitals should be permanent buildings or merely 
 temporary ones. The truth probably lies in the view that all 
 administrative arrangements, and a certain limited accommodation 
 for the infectious sick, should be in permanent buildings, which 
 existing thus ready to hand in non-epidemic times can be quickly 
 supplemented by additional wards in either huts or tents within 
 a few days, in case of widespread epidemics. Some means ot 
 
246 SOILS, SITES, AND BUILDINGS. 
 
 isolation are needed in every community at all times, and it is a 
 sounder policy to be able to delay and prevent epidemic outbreaks 
 by isolating the few sporadic cases as they occur, in a small but 
 permanent infectious-disease hospital, than have to grapple with 
 epidemics already in full existence by means of hastily constructed, 
 expensive, and often costly temporary structures. Many materials 
 have been suggested for the construction of these temporary 
 buildings, more particularly wood, galvanized iron, canvas, and 
 waterproof paper. Although thev are comparatively cheap an<f 
 rapidly erected, temporary hospitals should never be regarded as 
 able to supersede permanent buildings of brick or stone; their 
 true use is to supplement, not to supersede. Moreover, they are 
 extremely difficult to ventilate and to warm in winter or cool in 
 summer. Their durability is small, and their proper disinfection 
 is almost impossible. Of course they can be burnt when done 
 with ; but if epidemics of infectious disease rapidly succeed each 
 other, the renewals of temporary hospital buildings will soon 
 exceed the cost of structures of a more permanent nature. The 
 solution of the question probably lies in the construction of 
 hospitals of semi-permanent material. The frame of the structure 
 consists of light steel uprights and girders resting on concrete 
 foundations, and the wall spaces between the steel supports being 
 double uralite slabs so as to form a hollow wall. Such buildings 
 are cheaper to erect than permanent brick structures and 
 probably more lasting than galvanized iron or wooden huts. 
 For epidemic times expansion of accommodation can be made 
 by the erection of more temporary structures. The important 
 point to be remembered is that the provision for isolating in- 
 fectious cases is best carried out with deliberation in non-epidemic 
 periods. 
 
 It is perhaps needless to remark that in all hospitals the need 
 for speedy and efficient removal of all excreta and refuse is of 
 paramount importance, as in private buildings. The principles to 
 be adopted are the same as have been explained. . 
 
 CHAPTER V. 
 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 Disposal of House and Town Refuse. — The simplest method 
 is to burn the contents of dustbins and ashpits, which consist of 
 dry refuse, paper, rags, and other more or less combustible material, 
 and subsequently bury the residue in the ground. Animal and 
 
DISPOSAL OF HOUSE AND TOWN REFUSE. 247 
 
 vegetable refuse may also be dealt within this way, and, if covered 
 or mixed with ashes, its combustion can be secured slowly without 
 any offensive odours being given off. This simple procedure is, 
 however, only possible in the case of more or less isolated houses in 
 country districts ; in towns and other populated areas it is quite 
 impracticable — in fact, the effective disposal of civic waste constitutes 
 one of the greatest difficulties which every sanitary authority has 
 to face. The difficulty is further increased by the fact that the 
 material to be dealt with varies in quality and quantity according 
 to the season, the kind of fuel used, and the habits of the people. 
 The magnitude of this problem of refuse disposal is apparent when 
 we realize that, for urban areas, the quantity of ashbin refuse 
 averages from 240 to 260 tons annually for each 1000 inhabitants. 
 Much of this might be obviated if individual householders would 
 burn in their own grates such materials as bits of paper, rags, 
 potato peelings, cabbage leaves, and similar substances. Few, 
 however, do so, with the result that the average dustbin contains 
 an objectionable amount of readily decomposable material, which, 
 unless rapidly and effectively removed, conduces soon to become 
 an actual and serious menace to health. 
 
 The removal of house refuse, in most towns, is carried out 
 weekly, while in a few places removal twice or thrice a week is 
 secured. A daily removal is most desirable, as decomposition 
 and its attendant dangers are thereby reduced to a minimum. 
 What becomes of this refuse matter varies according to local 
 circumstances, but in all cases it should be conveyed through the 
 streets in covered carts only. In some places, this dustbin refuse 
 is used for the filling in of pits and excavations, or for raising the 
 level of low-lying land preparatory for utilization as building sites ; 
 this is a most pernicious practice, and should be discouraged in 
 every way. An alternative procedure is to sift and sort the refuse 
 at a depot. The cinders and coal, along with the fine ashes, are 
 sold to brickmakers as " breeze ; " the clinkers, broken crockery, 
 etc., or "hard core," is used for road-making ; and the " soft core," 
 consisting of vegetable and animal refuse, is sold for manure. 
 The remaining substances, such as scraps of iron, tin, paper, 
 bottles, rags, and corks, are separated out and sold. This process 
 is not commendable, mainly owing to its disgusting nature and 
 liability to unfavourably affect the health of those engaged in 
 sorting and sifting. A third and more usual method is to burn 
 all house and street refuse in special furnaces or destructors, which 
 destroy all combustible substances, leaving as a residuum a mass 
 of hard material, called clinkers, which may subsequently be 
 utilized for road-making or ground down and mixed with cement 
 to form pavement slabs. In certain places, the steam generated 
 
248 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 from boilers connected with these furnaces is utilized for electric 
 lighting, traction, water or sewage pumping, and other forms of 
 useful work. Hitherto, the evaporation of 1 lb. of water per 
 pound of refuse burned has been considered a good result, but 
 with modern furnaces an average evaporation of 1*43 lb. of water 
 can be obtained. 
 
 The object of every destructor is to convert the refuse into 
 fixed and harmless products by means of combustion, and the 
 transformation of organic matter into innocuous forms of vapour, 
 carbon dioxide, and nitrogen. Many types of destructor have 
 been designed, but those which have stood the test of experience 
 may be divided into two classes : (1) natural draught low-tempera- 
 ture furnaces ; (2) forced draught high-temperature furnaces. 
 
 ± 
 
 CIINKERIM5 
 
 fLOOR 
 
 Fig. 38. — Sectional view of a forced draught Refuse Destructcr. 
 
 The former class are represented by furnaces of the Fryer type, 
 in which a series of cells are arranged back to back. Each cell 
 has a sloping hearth and fire-grate, with top opening at the back 
 for the admission of refuse. Furnace frames and doors are pro- 
 vided for the removal of clinkers ; beneath the bars is situated 
 the ashpit, which is practically a reservoir into which the dust and 
 fine ash fall. The top of the destructor forms a level platform 
 upon which the refuse is tipped from the carts, and each furnace 
 has a feeding hopper, which discharges by means of a lever worked 
 from above. The employment of forced draught has resulted in 
 the production of high-temperature furnaces, in which the general 
 principles of construction are very similar to those of the Fryer 
 
NATURE AND COMPOSITION OF SEWAGE. 249 
 
 type. In the best modern forced draught, high-temperature 
 destructors the gases enter the boiler chamber at a temperature 
 of 2000 F., and in~a well-managed plant the temperature can be 
 maintained at 1600 F. The Horsfall back-to-back type is fitted 
 with forced draught, provided by two patent steam-blowers placed 
 at the end of the blast flues. By the use of these blowers the 
 temperature in the ashpit is increased to 400 F., the blast being 
 turned off when trimming the fires. In connection with some of 
 these installations, centrifugal dust-catchers have been constructed 
 and also solder extraction furnaces, designed to recover tin and 
 solder from old cans. In the Meldrum destructor the furnace has 
 one continuous grate with four sets of firing-doors, the products 
 of combustion having to pass over the whole range of fires. The 
 ashpit is divided into four closed compartments, each firing-door 
 having its own separate ashpit, in each of which are fixed two 
 blowers which draw their air through the generator. The 
 fires are clinkered from each door in rotation, three fires being 
 always kept charged, and the temperature of the furnaces main- 
 tained at incandescence. The gases pass from the combustion 
 chamber through a Lancashire boiler placed in the main flue. 
 The Heenan destructor is similar in many respects to the Meldrum 
 type, the cells being arranged in series, and the gases from each grate 
 deflected to each adjacent grate in turn by an undulating arch. 
 
 The average cost of burning refuse in these modern forced 
 draught destructors works out at about ij. Sd. in the metropolitan 
 area and is. a ton in the provinces ; but the efficient and economic 
 working of these furnaces depends largely upon supervision and 
 the maintenance of high temperatures, which can be obtained only 
 by continuous feeding. In addition to the regular and proper 
 feeding of the cells, it is necessary for the prevention of nuisance 
 that the fires be stoked regularly and systematically, and that the 
 blast be cut off each time during the clinkering process. Given a 
 good destructor and proper management, civic waste and house 
 refuse is reduced to about one-third of its original bulk, the residue 
 being innocuous clinker, metallic refuse, and dust. 
 
 Recent developments indicate that refuse may be efficiently 
 and economically dealt with by crushing to a fine powder 
 and the material then taken to farms and worked into land. 
 If not disposed of in this manner, the crushed refuse is mixed 
 with a tar product and then pressed into briquettes, which furnish 
 a furnace fuel of a very cheap character. The advantage of this 
 crushing process is that there is no need of sorting the refuse, as 
 tins, glass, and crockery ware are rapidly pulverised. 
 
 The Nature and Composition of Sewage. — The term "sewage" 
 includes not only human excreta, solid and liquid, but also the 
 
250 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 waste-water and impurities from houses and factories. From a 
 hygienic point of view, the excreta are the most important consti- 
 tuents, but besides the excreta and household wastes, sewage 
 contains rain and storm-waters, as well as water used in cleansing 
 or sprinkling streets ; sewage, therefore, is an extremely complex 
 fluid, varying in the same place from hour to hour both in its 
 volume and in its chemical composition. Although the total 
 amount of excretal matter is greater in sewage where water-closets 
 are in use, yet the average composition of such sewage is no 
 stronger than that from towns where there are no water-closets. 
 The reason for this is that ordinary domestic slop or waste-water 
 is usually a very foul liquid, and that the existence of water-closets 
 means a plentiful water supply, which is sufficient to dilute the sewage 
 to as low a strength as that derived from a non-water-closet town. 
 
 The total quantity of sewage depends largely upon the amount 
 of pure water supplied per head per day; in the same manner 
 the solids in solution in any given sewage vary with the quality 
 of the drinking water. 
 
 The Removal of Sewage. — There are two main methods of 
 getting rid of sewage from the dwelling — they are the conser- 
 vancy and water-carriage methods. The former has to be 
 employed where tub, pail, and midden closets are in use, the 
 latter where water-closets exist. As to the relative merits of 
 the two methods, no absolute answer can be given in exclusive 
 favour of either. Each is the best under different circumstances. 
 For isolated houses, small villages, and for temporary collections 
 of people, as in camps, the dry method is suitable ; its efficient 
 working, however, is dependent upon adequate supervision and 
 the greatest care as to details. Although the initial outlay in 
 closets and sewers is small where the dry method is used, there 
 is the constantly recurring cost of removing the excreta as well 
 as of cleansing the pails, etc. ; further, some provision has to 
 be made for carrying off slop-water, some urine, and possibly 
 a certain amount of liquid trade products as well. The chief 
 objection, however, to the system is the fact that the excreta 
 are retained for some time in or about the dwelling, instead of 
 being removed immediately. For these reasons, the water- 
 carriage of sewage is indispensable in towns; its advantages 
 are that it is the cleanest, readiest, and in many cases the 
 cheapest method. The success of this plan depends on there 
 being a good supply of water, properly constructed sewers, with 
 good ventilation and proper outfall and means of disposal of 
 the sewer-water. The quantity of water necessary to flush sewers 
 and maintain them in a healthy state is about 25 gallons per head 
 per day. If rain-water passes in, it flushes the sewers thoroughly 
 
SOIL-PIPES. 
 
 251 
 
 sometimes ; but it also carries in gravel and debris, and may 
 surcharge the sewers in certain cases, to provide against which 
 storm-overflows have to be provided. 
 
 The chief sanitary installations connected with a water-carriage 
 system of sewage removal are water-closets, soil-pipes, drains, waste- 
 pipes from baths, sinks, or rain-water gutters and sewers. As the 
 essential features of water-closets have already been explained, we 
 may now consider the other appliances in detail. 
 
 Soil-pipes are pipes for immediately carrying away excreta or 
 sewage from the water-closet to the house-drain. Throughout 
 their course they should be ob- 
 servable, and consequently not 
 be built into walls, but preferably 
 carried at once outside through 
 the house-wall, immediately be- 
 yond the siphon bend or trap of 
 the closet. Soil-pipes may be 
 made of drawn lead, of at least 
 8 lbs. per superficial foot, and all 
 joints be of the kind known as 
 " wiped." Iron pipes are more 
 generally used, but must be 
 smooth inside, and protected 
 either by Angus Smith's preser- 
 vative, or coated with a vitreous 
 glaze. In iron pipes the joints 
 must be caulked with lead. A 
 soil-pipe should not be less than 
 3^ inches in diameter, and con- 
 tinued from its highest point well 
 above the roof by a pipe of the 
 same size, with the fewest angles 
 or bends, and terminating by an 
 open aperture well away from all 
 windows or chimneys. The con- 
 nection between the closet-basin 
 and the pipe is often difficult, as 
 the basin is generally made of 
 earthenware and the pipe of metal. 
 Doulton's patent ceramic joint obviates this difficulty, and a 
 perfect union is formed. 
 
 Where several closets on different floors discharge into the 
 same soil-pipe, the discharge of water down the soil-pipe may 
 cause unsealing of the traps of the water-closets. This unsealing 
 is prevented in the case of the highest closet by the ventilated 
 
 Fig. 39. — Showing soil and anti-siphonage 
 pipes (.Bennett). 
 
252 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 soil-pipe, but not always so for the lower closets. For these it is 
 desirable to carry a pipe from the highest point of the closet-trap, 
 where it joins the soil-pipe, through the wall into the outer air. 
 Such an anti-siphonage pipe effectually prevents the water being 
 sucked out of the trap of a lower water-closet when the one on a 
 higher floor is being flushed. 
 
 The soil-pipe discharges direct into the drain, and at this point 
 it is undesirable to place any trap, as it imposes a useless impedi- 
 ment to the passage of the sewage from the soil-pipe to the drain, 
 and prevents the soil-pipe acting as a drain ventilator. 
 
 Fig. 39 shows a tier of three water-closets fixed one above 
 another. The upper one is a valve-closet connected to an anti-D 
 trap^ with ventilating pipes to trap, and valve-box. The middle 
 one is a wash-down pedestal water-closet, with a ventilated branch 
 soil-pipe. On the ground floor is a siphonic action water-closet. 
 The whole of the closets are connected to a lead soil-pipe, the 
 branch soil-pipes being fitted with branch ventilating or anti- 
 siphonage pipes. The main soil-pipe is connected by an earthen- 
 ware rest-bend to the drain, which is supported on a bed of 
 concrete. 
 
 The House-drain receives, ordinarily, not only the discharge 
 from the water-closets by the soil-pipe, but also rain-water, and 
 waste water from baths and sinks. Drains may be made of either 
 stoneware or of iron. They should be laid in straight lines, each 
 pipe being placed with the spigot and not the socket end directed 
 towards the flow of sewage. The usual size of a main house- 
 drain is 6 inches, but branch drains rarely exceed 4 inches in 
 diameter. Their fall should not be less than 1 in 40 or 60. Small 
 drains are more completely self-cleansing than large ones. Stone- 
 ware drains should be laid on a bed of concrete at least 6 inches 
 thick, so as to prevent subsidence, and if carried under a house 
 they should be covered with an equal thickness of concrete. 
 Joints should be made with cement, and on no account with clay. 
 Drains made of iron are coming into use; they are certainly 
 preferable to stoneware, as being less liable to fracture, and more 
 readily made water-tight at the joints. Just before the drain 
 leaves the curtilage of a house, and near its junction with the 
 sewer, it should be trapped, and on the house side of this trap an 
 inlet ventilator should be provided. This inlet may be placed at 
 the ground-level, or a few feet above the ground. The exit for 
 air entering by this inlet is provided by the upper end of the soil- 
 pipe carried full-bore above the eaves. By this arrangement a 
 complete ventilation of the house-drain is secured, and a free 
 escape of any foul gases directed out-of-doors. 
 
 The form of trap intercepting the drain from the sewer is 
 
TRAPS. 
 
 253 
 
 often of the kind shown in Fig. 40, and not infrequently 
 associated with some form of manhole or inspection chamber. 
 This, if close to the house, is provided with an air-tight cover, 
 the inlet ventilator being arranged at some convenient point. 
 The manhole is built of brick set in cement, and in it half- 
 channel pipes convey the sewage instead of complete pipes. 
 
 23!'—-- -* 
 
 Fig. 40. — Disconnecting trap with cleaning eye. 
 
 Where two or more drains converge to any one point, the loca- 
 tion of an inspection chamber or manhole is desirable, as facili- 
 tating access and inspection in the eve*nt of accidental stopping. 
 
 Traps are used as barriers to prevent the passage of sewer- 
 air into houses. A good trap should completely disconnect the 
 
 Fig. 41. — Siphon-bend. 
 
 Fig 42. — Disconnecting trap. 
 
 air in one pipe from that in another. This is done by means 
 of a water-seal, which should never be less than to allow the 
 water to stand three-quarters of an inch above the dip of the trap. 
 The trap itself should be of such a form as to allow of its 
 
254 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 being completely washed out with every flush of water passed 
 through it. Traps are almost of infinite variety, but the following 
 represent common types. 
 
 The ordinary sip/ion-tTsup consists of a curved tube, the curve 
 being full of water, which should stand at least three-quarters of 
 an inch above the top of the curve or dip. If two siphon-traps 
 succeed each other, one will- suck the other dry, unless an air- 
 opening is placed between them ; traps based on siphon-trap 
 principle are best. These simple bends, however, are rarely used 
 in good work. A more common form of disconnecting trap is 
 that shown in Fig. 42. 
 
 An ordinary gully-trap is shown in Fig. 43, while Fig. 45 
 represents that known as Dean's trap, suitable for paths or 
 
 places where much silt or sand 
 washes into surface drains. 
 
 Mason's or the dipsto?te-\x2^ 
 consists of a round or square 
 chamber, with an entry tube on 
 one side and an exit tube at the 
 same height on the other ; water 
 stands in the trap up to the lower 
 margin of each pipe, and a 
 partition passes down between 
 into the water (Fig. 46). It is a bad form of trap, as it is 
 not self-cleansing, and fails in all the essentials of a good trap ; 
 
 Fig. 43.— Gully-trap. 
 
 Fig. 44. — Siphon sink-trap with movable 
 screw for cleaning. 
 
 Fig. 45. — Dean's gully-trap. 
 
 it is also liable to leak under the covering-stone, when the gas 
 readily escapes. 
 
 The bell-trap is a modification of the dipstone principle ; it is 
 a very inefficient form of trap, as the bell portion is removable, 
 and when taken off the water-seal is done away with (Fig. 47). 
 
TRAPS. 
 
 255 
 
 The flap-trap is a hinged valve allowing water to pass in one 
 direction : it was expected that this would prevent the reflux of 
 sewer-air, but it has been found to act very imperfectly, and is 
 useless to prevent sewer-gas returning. 
 
 The ball-trap is one in which a ball rises with the rise of 
 water and closes an orifice ; it is a very imperfect form of trap. 
 
 Gully-traps should be at least 18 inches from the wall of the 
 house, and their superficial surface should be as small as possible, 
 so as to diminish the evaporation of water. 
 
 Fig. 46. — Dipstone-trap. 
 
 Siphon-traps, however perfectly made, cannot be relied on 
 to prevent the passage of sewer-air. Water alone cannot 
 always resist the pressure of air, and even if it accomplishes 
 this, it will absorb foul gas from below and emit it above ; 
 hence the absolute necessity for the disconnection and the 
 ventilation of the sewers. 
 
 To prevent the deposit of grease or sand in the drain-pipe, 
 scullery sinks require to be provided with a grease-intercepting 
 chamber; if grease is allowed to flow into the drain, it may 
 gradually stop up the pipe by adhering to the sides, and is 
 then difficult to remove. This chamber is generally made of 
 hollow stoneware, with a tight iron cover, and ventilated. The 
 hot greasy water from the sink is discharged at the bottom of 
 the chamber, the grease is then cooled and rises to the surface 
 for removal, the sand sinking to the bottom, while the water 
 passes away to the drain. The grease and sand must be removed 
 every second or third day. 
 
 Grease-traps may be classed with ordinary gully-traps. They 
 should not generally be used for ordinary kitchen or scullery 
 sinks, but may be necessary when a large amount of grease is 
 passed off, as in hotels, etc. Grease-traps partake of the nature 
 of cesspools, and should not be used when avoidable. 
 
 Concerning traps generally, engineers look suspiciously on 
 every one of them, and endeavour to render them unnecessary 
 by thorough ventilation and disconnection of the drains. 
 
 The essentials of a good trap are that the water stands at least 
 
256 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 three-quarters of an inch above the openings, that the trap itself 
 be self-cleansing, that is, all the contained water should be effectu- 
 ally changed by every flush. A trap is only efficient so long as it 
 contains water : if therefore a trap exposed to the air, such as a 
 gully-trap or a hopper closet trap, is not in constant use, especially 
 in hot weather, the water evaporates, and direct communication 
 is established with the drain. In dry weather it is desirable to 
 see that unused traps are charged with water. 
 
 Waste-pipes discharging water from kitchen sinks, sculleries, 
 etc., and bath-waste pipes carrying away water from baths, should 
 not connect directly with any drain, but must discharge into 
 the open air, over a good water-trap. Waste-pipes should also 
 have a siphon-trap on their course with a 3-inch water-seal. They 
 should not be connected with any soil-pipe. 
 
 Waste-water pipes are best made of lead, and should be 
 sufficiently strong to resist the action of expansion and con- 
 traction, caused by hot and cold water; they are generally 
 2 inches in diameter. 
 
 Rain-water pipes should also discharge their contents over 
 a trapped gully, so as to be completely cut off from the 
 drain. 
 
 The Examination of Drains. — In practice this amounts to the 
 application of certain tests for the determination of soundness. 
 Two chief methods of testing drains are in use, namely, by smoke 
 or volatile agents, and by water. The smoke-test consists in 
 filling the drain or soil-pipe with smoke, the assumption being 
 that this will find its way through any leak, faulty joint, or trap, 
 thus indicating the site of the defect. The smoke may be forced 
 into the pipe or drain from a pumping apparatus, or be produced 
 within the drain from a specially prepared grenade or rocket. 
 An alternative procedure is to pour a table-spoonful of oil of 
 peppermint, mixed with hot water, either down the highest water- 
 closet or down the pipe at the highest point available; as this is 
 a very volatile and pungent oil, there is no difficulty in tracing 
 where the odour is emitted, and so detecting the leak. Although 
 convenient for testing traps and fittings above ground, these tests 
 are of little value in the examination of underground pipes. The 
 only absolutely trustworthy test for drains is the water-test. 
 Having plugged up the lower end of the drain by a suitable water- 
 tight stopper, the drain is gradually filled with water. If the water- 
 level remains constant for half an hour or more, the drain may be 
 considered sound and water-tight. If it will not fill, or the level 
 falls rapidly after filling, there is leakage somewhere, and it will 
 be necessary to open it up and repair, or perhaps relay the drain. 
 
 In applying the water-test to drains, it must be remembered 
 
SEWERS. 257 
 
 that each foot of water-head exercises a pressure within the pipe 
 or drain of 0*432 pound on the square inch, or to find the head of 
 water required to obtain any given pressure, this, in pounds per 
 inch, if multiplied by 2*31, will give the head in feet. It is 
 doubtful whether, in the routine examination of drains, it is desir- 
 able to put any considerable pressure on the drain as defects may 
 be caused which did not before exist. If stoppage of the drain 
 occurs, and there are manholes or access pipes provided, the spot 
 where the obstruction takes place can be easily localized ; but if 
 no such arrangement exists, the drain or pipe will have to be 
 broken in one or more places, until the point of stoppage is found. 
 Brisk flushing with water will generally remove any obstruction. 
 Stoppage may be caused from imperfect laying of the drain, from 
 improperly finished-off joints, so that a rough surface is left on the 
 inside of the pipe ; or roots of trees may find their way through 
 the joints of earthenware pipes, when clay is used for jointing. 
 The most frequent cause of stoppage, however, is that various 
 articles are improperly thrown down the water-closet, and gradually 
 fill up the pipe. 
 
 Sewers are the trunk canals into which the house-drains empty 
 their contents. The system of sewerage now generally adopted 
 in England is the " combined system ; " in this system the surface 
 drainage and rain-water are carried off bv the same channels as 
 the sewage. Sometimes separate drains are provided to carry off 
 the rainfall; this is called the "separate system," and involves 
 two sets of drains ; one to carry off the rain and storm waters, 
 the washing of streets and open spaces ; the other to carry off 
 the sewage. The former discharge their contents into the nearest 
 river or watercourse ; the latter will convey the sewage to be 
 treated by some one of the methods described subsequently. The 
 advantages claimed for this are that smaller sewers are required, 
 and that the amount of sewer-water is less, richer in quality, and 
 more regular in flow ; no storm-waters enter the sewers to flood 
 the lower districts of the town, and no road detritus is washed into 
 the sewers. The disadvantages are that the drainage system is 
 practically duplicated, and rain-water washes away much that would 
 pollute a stream ; the scouring effect of rain on sewers is also lost, 
 but this is a doubtful objection. Adoption of either plan must 
 depend on local. circumstances. 
 
 Considerable economy could be effected, in connection with 
 drainage of small dwellings, by adoption of a common drain or 
 sectional drainage. This common drain to collect the drainage 
 from not more than 15 houses and to deliver at one point into the 
 main sewer, instead of requiring each house to have its drainage 
 system separately connected. The latter involves separate dis- 
 
 K 
 
258 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 connecting traps, manholes, and ventilation arrangements for each 
 house with a separate connection cut across the road to the sewer. 
 Where there is a duplicate system with one connection to the 
 sewer and another to the rain-water system the savings are 
 increased. The adoption of the common drain system from 14 
 to 15 houses to the sewer is particularly suitable for municipal 
 housing schemes in which the local authority is not only the 
 owner of the property but also, under recent legal decisions, 
 responsible for maintaining the common drain. 
 
 Perforated Iron Door. 
 
 From, House. 
 
 J ,..->yi •>■'■ -:'«». ) 
 
 Cieaning Branch. 
 \ To Sewer. 
 
 Fig. 48. — Disconnecting manhole. 
 
 In every system of sewage two objects are generally aimed 
 at : first, sewage has to be removed, and this should be done 
 by impervious pipes, such as glazed stoneware or iron, or brick- 
 work laid in cement, very carefully laid and jointed ; and secondly, 
 when necessary, the subsoil must be drained. This may require 
 pervious drains or drain-sewers. If pipe-sewers only are used, the 
 subsoil water remains unaffected, except so far as a small portion 
 may find its way along the channels formed by the pipe. Some- 
 times pervious drains of earthenware are laid down to carry off the 
 subsoil water. 
 
 Sewers up to 18 inches diameter are generally made in stone- 
 ware and are circular in section. Concrete pipes are also largely 
 used for the larger diameters. These are preferable to stoneware 
 and generally cheaper. Cast-iron pipes are also used under certain 
 circumstances, they should be coated with Angus Smith's preserva- 
 tive to prevent corrosion. If fluctuations in the amount of sewage 
 are great, an egg-shaped sewer is preferable to the circular form ; 
 but if there is sufficient sewage to keep sewers constantly running, 
 say half full, the circular section is best, being cheapest and 
 strongest If stoneware pipes are used, it is advisable to lay a 
 foundation of concrete which supports the pipes in their length, 
 and not at the sockets only. The pipes should also be packed at 
 
SEWERS. 
 
 m 
 
 their sides to prevent their being crushed. The joints must be 
 cemented, and not puddled with clay, care being taken that the 
 cement does not get inside the pipes, forming projections in the 
 sewer against which solid matters will lodge and obstruct the flow 
 of the sewage. 
 
 To avoid deposition of sediment, sewers should be laid in as 
 straight lines as possible and with a regular fall ; junctions should 
 be made oblique, so that the sewage may enter in the direction of 
 the flow. The junction of drains is made by a special form of 
 pipe, which may be either single or double. If the sewer curves 
 it should describe a wide sweep, the radius of the curve not being 
 less than ten times the cross-sectional diameter of the sewer. In- 
 spection of pipes may be provided for by a manhole or by the 
 arm of a disconnecting trap (Figs. 48, 49, and 50). 
 
 
 
 Fig. 49. — View of inspection chamber 
 from above. 
 
 Fig. 50. — Sectional view of an inspection 
 chamber. 
 
 Main sewers are generally made of well-cemented brickwork 
 and egg-shaped in form, to give greater hydraulic depth, and, 
 therefore, increased velocity with a small quantity of fluid. The 
 egg-shaped sewer is formed by two circles touching one another ; 
 the diameter of the upper circle equals twice that of the lower, 
 so that the invert is the narrowest part. This form of sewer 
 secures the maximum scouring effect with the minimum quantity 
 of water. 
 
 To secure a uniform flow, it is necessary to diminish friction 
 as much as possible ; and this is found to be least in this form of 
 sewer, as the wetted perimeter is proportionately reduced, instead 
 of being, as in every other form, relatively increased. The interior 
 should be smoothly finished, and the sewer itself quite impervious 
 and free from any inequality. 
 
 At each principal change of line or gradient there should be 
 arrangements for inspecting flushing and ventilation ; at all 
 junctions and curves the fall should be increased to compensate 
 
260 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 for friction ; the principal sewers should have special overflow 
 pipes for any excess of rainfall ; no junctions should be at right 
 angles, nor opposite other junctions ; tributary sewers should 
 deliver in the direction of the main flow, and should have a fall 
 into the main at least equal to the difference between their two 
 diameters ; pipes of small size should always join on to pipes 
 of larger size ; if the tributary joins the main sewer below 
 the level of the sewage in the latter, deposits are produced 
 in the branch. Street gullies are generally provided to prevent 
 the entry of gravel and solid matters into sewers. The debris 
 collects in the gullies, while the water flows off by an opening 
 to the sewer placed on a higher level, and the deposit is removed 
 at intervals. 
 
 Fall of Sewers. — The amount of fall that should be given 
 to sewers, or the inclination at which they should be laid, 
 will depend upon the velocity of the current that it is desired 
 to attain. To prevent deposit, in drains of 4 and 6 inches 
 diameter the velocity should not be less than 3 feet per second; 
 for drains of larger size a less velocity will suffice. 
 
 The inclination or fall required is 1 inch in 40 for 4-inch 
 drain, and 1 in 60 for a 6-inch drain, and for sewers from 1 in 244 
 to 1 in 784 according to size. Too deep an incline has a tendency 
 to cause the water to run away too forcibly, leaving the solid 
 matter behind. 'If the fall is less, or if deposits occur, special 
 means for cleansing are required. This is usually accomplished 
 by manholes placed at intervals, the sewers running in straight 
 lines from manhole to manhole. When the current is feeble and 
 deposits are liable to occur, automatic flush-tanks may be placed 
 at the upper end of the sewer. Flushing is chiefly required in 
 sewers with insufficient gradients, at " dead ends," and in hot 
 dry seasons when the flow of sewage is smallest and decom- 
 position most rapid. Automatic flush-tanks may be used for this 
 purpose ; they act by siphonage, so that the whole cistern 
 empties itself with a sudden flush when the action is once started 
 (Fig. 51). 
 
 The action of the cistern is as follows : The base of the tube 
 dips into the trapping-box, then, as the water rises in the cistern, 
 it compresses the air in the tube. The water continues to rise in 
 the dome of the siphon until it reaches the level of the lip, when 
 on overflowing, the water falls down the centre of the tube, carry- 
 ing with it a certain amount of air. This action continues until a 
 partial vacuum is formed in the inner tube, and the siphonic 
 action due to the pressure of the atmosphere is commenced, 
 when the whole contents of the cistern are discharged with great 
 velocity. An important point to bear in mind is that, on fixing 
 
FALL OF SEWERS. 
 
 26l 
 
 one of these cisterns, the dome of the siphon must be removed, 
 and a few gallons of water poured into the lower chamber so as 
 to form a trap. 
 
 The simplest formula for calculating velocity of flow through 
 circular sewers or pipes is the following : — ■ 
 
 v = 55 x Jd x 2F 
 
 V = velocity in feet per minute. 
 D = hydraulic mean depth in feet 
 F = fall in feet per mile. 
 
 V X sectional area of current of fluid, in sq. feet, = discharge 
 
 in cubic feet per minute X 6*23 = gallons per minute. 
 
 Fig. si.— Field's flush-tank. 
 
 To use this formula, the hydraulic mean depth when the 
 sewage is flowing, and the amount of fall in feet per mile, must be 
 first ascertained. Fall in fractional parts is converted into fall 
 in feet per mile by dividing 5280 (number of feet in a mile) by 
 the denominator of the fraction. Thus a fall of 1 foot per 
 mile = 1 in 5280 ; 10 feet per mile, 1 in 528, and so on. 
 
 The hydraulic mean depth of a pipe of any shape equals the 
 section area of the current of fluid divided by the wetted 
 perimeter. The wetted perimeter is that part of the circum- 
 ference of the pipe which is in contact with the fluid. The 
 hydraulic mean depth in circular pipes, running full or half full, is 
 one-fourth of the diameter. 
 
 The area of an egg-shaped sewer can be calculated by 
 squaring the radius of the larger circle and multiplying by 
 
262 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 4'6 ; the discharge in cubic feet per second for egg-shaped 
 sewers flowing two-thirds full can be calculated from the formula 
 
 Q = zSsjd^ji where d is the diameter of the larger circle, 
 
 / is the fall, and / is the length. The velocity of flow in feet 
 per second through an egg-shaped sewer can be expressed as 
 being 128 X 10 VH 7 X VF, where H is the hydraulic mean 
 depth, F is the fall, and 128 is a constant derived from the 
 ratio of the coefficients for acceleration from gravity and for 
 roughness of surfaces. 
 
 A 
 
 JO 
 
 I 
 
 Fig. 52. — Egg-shaped Sewer. 
 
 Sewer Air. — In well-constructed sewers, where there is no 
 deposit and the sewage is allowed to flow away without any 
 obstacle to the outlets, the air is much better than might be 
 expected. Observations indicate that the carbon dioxide is about 
 twice, and the organic matter, estimated by the permanganate 
 process, about three times as great as in the outside air at the 
 same time ; while the number of micro-organisms is less in sewer 
 air than in the outside air. The excess of carbon dioxide is 
 probably due to the oxidation of the organic matter in the sewage 
 and in the sewer air, and, in part, to the diffusion into the sewer 
 of air from the neighbouring soil. The few micro-organisms 
 present, compared with the external air, is explained by the 
 tendency these have to be deposited on the damp surfaces of the 
 
VENTILATION OF SEWERS. 263 
 
 sewers ; with ordinary air-currents they are not disturbed or given 
 off to the surrounding atmosphere ; those present nearly all come 
 from the outside air, their number being directly proportional to 
 the number present in the external air at the time. In the 
 absence of splashing or bursting of bubbles due to fermentation 
 in the sewer, there is little ground for supposing that the micro- 
 organisms in sewage become disseminated in the sewer air. In 
 badly constructed sewers, or where deposits take place which 
 undergo putrefaction, such favourable results are not found, and 
 disease has been traced to the entry of infected sewer gas into 
 houses through untrapped drains and openings into them. A 
 distinction must be drawn between sewer air and sewer gas ; the 
 former is generally without smell and harmless, while the latter is 
 always the result of stagnation, deposit, and putrefaction. 
 
 Ventilation of Sewers. — Sewers cannot be constructed air- 
 tight on account of the very numerous openings into them ; the 
 tension of the air is generally not very different from that of 
 the atmosphere outside, while the movement of the air is usually 
 upstream, except where the depth of flow is considerable when 
 the movement may be reversed. Certain conditions, however, 
 are present which produce movement of air in sewers, the chief 
 being — the variation in temperature in the sewer and in the 
 external air; barometric pressure; the passage of hot water from 
 houses or manufactories, causing a rise of temperature in the 
 sewage and consequent expansion of the air in the sewer; the 
 blowing off of steam, which increases the temperature and pressure 
 suddenly ; and the sudden increase of water flowing into the 
 sewers. Any of these conditions may expel air from the sewer 
 or draw air in from the external atmosphere. Tidal water in 
 sewers is not so liable to cause violent movements of the air in 
 them, as the rise of the tide is gradual. The question of the best 
 methods of ventilating sewers is a very vexed one, as movement 
 of air in sewers depends upon the many conditions mentioned 
 above. 
 
 The simplest plan for ventilating sewers is by means of a 
 shaft from the crown of the sewer to the surface of the street or 
 road above, where it is covered by an iron grid. The mud and 
 gravel which may fall through the grid is caught in a tray placed 
 beneath the grating, but which allows the free passage of air 
 around it. One such opening is placed commonly at intervals of 
 a hundred yards or so. This system has been subjected to much 
 criticism, mainly on account of the fact that it favours the dis- 
 charge of objectionable gases from sewers more or less immedi- 
 ately under the noses of passers-by. As a routine practice, this 
 plan of opening ventilating grids at road level is to be discouraged. 
 
264 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 A preferable method is to locate along their course at suitable 
 intervals tall iron shafts, provided with rust pockets, and carried 
 sufficiently high as to permit of the escape of air and gases at a 
 level well above the roofs of houses. As a matter of fact, however, 
 if sewers are well constructed, have sufficient fall and flush of water, 
 obviating the local accumulation of decomposing material, there 
 should be no accumulation of foul gases. These ideal conditions, 
 however, are not always existent ; in which cases the only way to 
 cope with the nuisance from sewer emanations is by abolishing 
 dead ends of sewers or ventilating them, by erecting pipe ventila- 
 tors in substitution of offensive gratings at street level, and the free 
 admission or circulation of air in the sewers. The latter detail will 
 do good by favouring oxidation of any putrescent matter and by 
 diluting any offensive gases evolved. It has been suggested to 
 solve this question of sewer ventilation by the abolition of the 
 intercepting trap on the house-drain between the sewer and the 
 house, thereby converting every house-drain and the soil-pipes 
 discharging thereto into so many sewer ventilators. The main 
 objection to this proposal is that it would destroy the drain 
 isolation, which is now possible, of each house from the rest of 
 the houses of a district. Moreover, as we cannot rely absolutely 
 upon the soundness of every sanitary fitting in individual houses, 
 the risks of sewer gas gaining direct access into dwellings would 
 be considerable. It is true the intercepting trap is not an ideal 
 sanitary appliance, but we have to choose between two evils, 
 namely, having sewer gas laid on to the house, or having the 
 efficiency of the house-drain somewhat interfered with ; and the 
 latter is the lesser evil. 
 
 In circumstances where there is a sectional drainage and a 
 common drain serving 14 or 15 houses there should be one 
 connection to the sewer from that common drain, with an inter- 
 cepting trap and manhole on the common drain within the section 
 drained as near as convenient to the junction w T ith the sewer. 
 The system should be ventilated by a fresh air inlet or vent pipe 
 placed at the manhole containing the intercepting trap, also 
 another air inlet at the head of the common drain, while each 
 separate block of dwellings must have a vent pipe at or near the 
 highest point of the common drain adjoining, the vent to be 
 carried up clear of the eaves of the building. A manhole should 
 be provided where two common drains form a junction, and 
 inspection chambers or rodding eyes so placed that no drain 
 exceeding 100 feet in length is without means of cleaning or 
 ventilation. Rodding eyes must be provided also where a change 
 in direction of the drain or a branch connection renders it 
 desirable. All pipe connections must be by oblique bends or 
 
DISPOSAL OF SEWAGE. 265 
 
 easy curves. All connections from the dwelling should be 
 bought into the w.c. branch drain as near the buildings as 
 possible, so as to reduce the number of connections to the 
 common drain. 
 
 Pneumatic Methods of removing Sewage. — These are practi- 
 cally three in number, namely, the Liernur, the Berber, and the 
 Shone systems. The first two are extraction methods working by 
 means of a vacuum produced from a central air-pump station. 
 These systems need specially constructed pipes and tanks or 
 reservoirs, all being air-tight. They are complicated systems, 
 practically never used in this country, and only needed in low- 
 lying districts where suitable sewer gradients are difficult to 
 secure. The Berber system has the advantage of being more or 
 less automatic in its working. The Shone system is really a 
 device for raising sewage from one level to another, when the 
 ground is very flat and a proper fall for the sewers cannot be 
 secured. It works by compressed air generated at a central 
 station and laid on in pipes to ejectors provided at various points. 
 We are disposed to think that as good results are obtainable by 
 steam pumping. 
 
 Disposal of Sewage. — This is still one of the most difficult 
 problems of the day. Although the question of the disposal of 
 sewage is distinct from that of its removal, yet the method of 
 disposal is dependent, to some extent, upon the method of re- 
 moval. In the dry method of removal the final disposal of the 
 fsecal matter is mainly as a fertilizer or manure upon cultivated 
 land. If the removal is by water, the ultimate disposal of the 
 sewage may be without any attempt at purification as by discharge 
 into the sea, running water, or into a cesspool ; or it may be 
 subjected to various methods of purification, such as separation of 
 the solid and liquid parts either by subsidence or precipitation by 
 chemicals, filtration through land, or various artificial media, and 
 bacterial methods. The final effluent being discharged either on 
 to land, or into the sea, or into some suitable stream or river. 
 
 Discharge into the Sea. — Under certain circumstances crude 
 sewage may be discharged directly into the sea without nuisance. 
 The outfall sewer must open always below the level of the water 
 at all states of the tide ; further, care must be taken to carry the 
 sewage well out to sea, so that it may not return with the tide and 
 be deposited on the fore-shore. Tidal currents and prevailing 
 winds must be studied and taken advantage of to prevent this ; 
 also the outlet of the sewer should be protected by a tide flap 
 opening outwards, to prevent ingress of tide and wind blowing up 
 the sewer ; the tide will block sewage at certain times, and this, 
 in the case of low- lying towns, necessitates a "tank sewer," to 
 
266 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 store the sewage that flows down during this period ; but with 
 this method, decomposition and evolution of gas and ammonia 
 compounds are very liable to take place; it requires special 
 attention. • 
 
 Discharge into Rivers, etc. — This is prohibited by the Rivers 
 Pollution Acts of 1876 and 1890. It is illegal to pollute any 
 stream or river by allowing crude sewage to flow into it. 
 
 The Cesspool System. — This system as a means of disposing 
 of crude sewage must be regarded only as temporary and partial ; 
 it provides for the immediate removal from the house of the 
 excreta and foul waters, but only to a short distance, where it is 
 received into a cesspool, from which the deposited solids must be 
 removed. Cesspools are generally constructed of brick, and in 
 the majority of cases the solid matters only are retained, the 
 liquids passing into the surrounding subsoil and infiltrating it for 
 some distance around. In some cases, to meet the requirements 
 of the local authorities, the cesspool is lined with cement, so as to 
 be impervious, and in this case an overflow-pipe must always be 
 provided, when the question of dealing with the liquid has to be 
 further considered. 
 
 The porous cesspool or dead-well is a method available only 
 in a country place. In this system the surrounding soil gets 
 polluted, and the water-supply must not be derived from any- 
 where near; the amount of percolation depends largely on the 
 nature of the soil. 
 
 Cesspools should be placed at least 50 feet distant from any 
 dwelling, and 100 feet or more from any well, spring, or stream, 
 according to the nature of the subsoil and the trend of the move- 
 ment of the underground water. They should always be at a 
 lower level than the well from which the drinking water is taken, 
 and to leeward of it, so as not to pollute the saturated portion of 
 the permeable stratum above the well. They should be ventilated 
 and emptied at regular intervals ; it is often found convenient to 
 utilize the liquid contents, by distributing this over the gardens or 
 adjoining fields, and for this purpose a small hand-pump is usually 
 attached, connected with a distributing-pipe or channel. Com- 
 plete disconnection of the house-drains by proper traps and 
 efficient ventilation are necessary to make this a sanitary method. 
 
 Purification of Sewage. — This presents great difficulties, and 
 many methods have been suggested and tried with varying suc- 
 cess. For the complete purification of sewage, three processes 
 are involved : first, clarification ; secondly, an alteration of the 
 chemical constitution of the organic putrescible matter in solution 
 in sewage, whereby it will not undergo any further putrefactive 
 changes ; thirdly, the removal of disease-producing bacteria. 
 
CHEMICAL TREATMENT. 267 
 
 These results are not obtained equally by the various methods 
 which have been suggested. The more important are the follow- 
 ing : chemical treatment, land treatment, and biological methods. 
 
 Chemical Treatment.— The processes suggested for the purifi- 
 cation of sewage under this head are mainly precipitation methods, 
 aiming at a more copious and rapid clarification of the crude 
 sewage than can be effected by subsidence alone. One of the 
 principal substances used for precipitating or clarifying sewage is 
 lime. The quantity used depends on the character of the sewage, 
 and varies from 5 to 10 grs. or more of quicklime for each gallon 
 of sewage. If the effluent is made alkaline by the addition of 
 too much lime it undergoes putrefaction rapidly; it has been 
 attempted to prevent this by adding chloride of iron to the quick- 
 lime, by which means purification is delayed but not prevented; 
 the process is simple and cheap, but as the organic matters in 
 suspension only are acted on, it has failed to produce either a 
 valuable manure or the purification of the offensive liquid. 
 Precipitation has little effect on the removal of microbes, patho- 
 genic or otherwise. 
 
 Among other processes which have been tried in different 
 places may be mentioned those which employ lime and alum, 
 lime and protosulphate of iron, also the ferrozone and alumino- 
 ferric precipitants. In London a chemical process has been 
 applied to the sewage before its discharge into the sea. This 
 consists in adding 5 grs. of lime and 2*5 grs. of protosulphate of 
 iron to every gallon of sewage ; it produces an average reduction 
 of 18 per cent, of dissolved oxidizable organic matter. 
 
 To ensure complete clarification of the sewage by chemical 
 precipitants, the sewage must be fresh and the larger solids 
 strained from it before the chemicals are added. The precipi- 
 tants are added before the sewage arrives at the subsidence tanks, 
 which must be sufficient to hold the dry weather flow for 24 hours. 
 The tanks are arranged in series so that the sewage may pass 
 slowly but continuously through two or four tanks before the 
 supernatant liquid escapes into the effluent channel. When the 
 tanks are full the flow of sewage is stopped and then allowed to 
 rest in the tanks for from two to four hours so that it may deposit 
 its sludge. The supernatant clarified liquid is then drawn off. 
 In order that the treatment of the sewage may continue whilst the 
 deposited sludge is being removed, there is always a second or 
 even third series of tanks provided. The sludge has to be 
 quickly removed and the tanks thoroughly cleaned out before 
 being refilled. The sludge is very putrescible and possesses very 
 little manurial value and often difficult to dispose of. It contains 
 90 per cent, of water, and is composed of the mineral and organic 
 
268 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 matters precipitated from the sewage. When pressed in a filter 
 the amount of water is reduced to 40 per cent. The pressed 
 sludge is sold or given away as manure. A preferable way is to 
 dry the sludge cakes by heat and then grind them into a powder ; 
 in this form the sludge is more manageable as a manure. 
 
 Occasionally, deodorants or antiseptics are added to sewage 
 as well as the chemical precipitants. Examples are the addition 
 of manganate of sodium and sulphuric acid, also a mixture of 
 milk of lime and herring brine known as the Amines process. 
 On the same principle of deodorization, attempts have been made 
 to purify sewage by electrolysis which generated hypochlorous 
 acid by decomposing the chlorides of sodium and magnesium 
 normally present in sewage. Another effort on the same lines 
 was the addition of electrolyzed sea-water to sewage. None of 
 these methods are reliable, and moreover are costly to carry out. 
 
 The sludge having been deposited in the sewage tanks, the 
 next question is what is to be done with the effluent or clarified 
 sewage ? The effluents obtained usually by chemical precipita- 
 tion of sewage are fairly satisfactory. They contain very little 
 suspended matter and much of the organic material of the original 
 sewage has been precipitated and retained in the sludge. If 
 passed into a river or stream whose volume is at least ten times 
 greater than that of the effluent, and which is not used below the 
 point of discharge as a source of drinking water, practically no 
 nuisance or harm will result. This ideal arrangement is rarely 
 possible and, moreover, it means the running to waste of the 
 valuable manurial constituents of the sewage. The only practical 
 means of disposing of these effluents is therefore to purify them 
 by carrying them over land by irrigation, or, if land is not 
 available, to pass them through specially constructed filter beds 
 consisting of coke, or gravel, or of sand laid on magnetic oxide 
 and carbide of iron. If the filtration be intermittent to allow of 
 aeration of the filters the final effluent is usually sufficiently , 
 satisfactory to be allowed to pass into small rivers or streams. 
 
 Land Treatment. — The utilization of land as a medium for the 
 purification and disposal of sewage has been accomplished in 
 various ways. The sewage is passed on to the land either in its 
 crude state or after some preliminary course of straining, or after 
 clarification and precipitation of its grosser suspended matter by 
 some form of chemical treatment. The application of sewage to 
 land is conducted usually on one or other of two methods, namely, 
 irrigation or intermittent downward filtration. If the sewage is 
 discharged on to a piece of land, having in view a maximum 
 growth of vegetation for the amount of sewage supplied, it is 
 known as irrigation • if it is discharged upon land specially 
 
LAND TREATMENT. 269 
 
 prepared to receive it, making the crops or product therefrom 
 of secondary importance, it is known as filtration. 
 
 In irrigation schemes, the soil must have a gentle slope and 
 be drained by subsoil drains placed about 5 or 6 feet deep, by 
 which the effluent can be conveyed to the nearest watercourse. 
 To ensure success, the area must be sufficient and the sewage 
 passed on at intervals, so as to permit of aeration of the soil. The 
 land is laid out in ridges and furrows, and the sewage made to 
 reach it in as fresh a state as possible, also freed from its coarser 
 material by settlement or precipitation. Although sewage farms 
 of this nature are not a commercial success, still immense crops 
 of coarse grass can be obtained from them. Under favourable 
 conditions, the purification of the sewage is excellent, the chief 
 disturbing factors being frost and excessive rainfall. For dealing 
 with sewage by this method, a large quantity of land is required — 
 about 1 acre for the sewage of 100 persons, the area varying 
 according to the porosity of the soil. 
 
 Land fifa-ation of sewage may be upward or downward ; the 
 former is now practically abandoned as being totally inefficient. 
 The process of filtration is essentially one of oxidation and 
 nitrification, while intermittency of application is a sine qua no?i, 
 even in suitable soils ; hence the process is commonly spoken of as 
 intermittent downward filtration. The action of the land is also 
 mechanical. As regards the soil itself, the physical conditions, 
 porosity and fineness of division, have more to do with its cleansing 
 power than its chemical composition. The best soil seems to be a 
 loose marl, containing hydrated iron oxide and alumina. 
 
 The conditions necessary for the successful filtration of sewage 
 through land are : (1) a porous soil ; (2) an effluent drain not less 
 than 6 feet from the surface ; (3) proper fall of land to allow the 
 sewage to spread over the whole land; and (4) division of filtering 
 area into four parts, each part to receive the sewage for six hours, 
 and to have an interval of eighteen hours. The quantity of land 
 required is about 1 acre to purify the sewage of 1000 persons, 
 and the larger solid bodies should be removed by straining before 
 allowing the sewage to flow on to the land. When the amount of 
 available land is limited, the sewage may be first treated by pre- 
 cipitation before allowing it to flow on the land, but this will 
 deprive it of much of its manurial value. Preferably it may be 
 passed through one or other kind of contact bed as described 
 subsequently under biological methods. If the crude sewage be 
 previously treated, one acre of land will suffice to receive the 
 sewage of from 2000 to 5000 persons. Other than for small 
 communities with suitable available land this method of disposal 
 of sewage is not very generally adopted in the present day. 
 
270 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 The effluent obtained is good after nitration of crude sewage 
 through land, provided the details of the procedure have been 
 carefully carried out, and is suitable for subsequent discharge into 
 any river or stream. The solids tend to form a fine cake on the 
 surface of the land, but these are readily broken up and worked 
 into the soil. Generally all crops grow well on these sewage 
 farms, but Italian rye grass and green vegetables do best. In 
 Paris all kinds of vegetables and fruit trees are grown, and appear 
 to thrive excellently under this treatment. When properly carried 
 out, this is a valuable method for the purification and utilization 
 of sewage, but it will be readily understood that, in view of the 
 difficulty experienced in obtaining a sufficient area of suitable 
 land, there are distinct limitations to its practicability. 
 
 Biological Methods. — Strictly speaking, the passage of sewage 
 on to and through land is a biological method of treatment, 
 inasmuch as it aims at, and more or less secures, a destruction of 
 sewage as sewage, and a building up of new substances in its place 
 by means of the organisms normally present in the sewage or in 
 the land through which it is made to filter. Until recent years, 
 land filtration was the only biological method of treating sewage 
 available or practised. The difficulties associated with the securing 
 of sufficient suitable land led to a closer study of the problem, and 
 the development of new applications of the biological treatment of 
 sewage has been a striking feature of recent sanitary effort. These 
 new departures depend essentially upon bacteria contained in the 
 sewage itself, and are based on the principle that organic changes 
 in sewage are mainly due to bacterial action, and aim at fostering 
 and assisting these changes by placing the sewage under the most 
 favourable conditions for undergoing disintegration and oxidation 
 by means of micro-organic life. Practically they are the direct 
 antithesis of all methods of treating sewage by chemicals which, 
 being for the most part antiseptic in action, modify and largely 
 neutralize the vital action of the bacteria present in sewage. The 
 micro-organisms existing normally in sewage may be said to consist 
 broadly of two classes, namely, the " anaerobes " or those which 
 exist without oxygen, and the " aerobes " or those to whom oxygen 
 is essential. To those of the first group falls the main share of the 
 work of breaking down, digesting, and liquefying the solid organic 
 matter of sewage, whereby it is reduced to simple chemical states, 
 chiefly ammonia ; while on those of the second group devolves 
 the duty and work of oxidizing, mineralizing, or nitrifying the 
 ammoniacaT substances into nitrites and nitrates. 
 
 The actual changes which take place in sewage, as the result 
 of bacterial action, are somewhat complex and obscure, but they 
 have been aptly described by Rideal as consisting mainly of three 
 
BIOLOGICAL METHODS. 27 1 
 
 stages. In the first stage, or that of anaerobic liquefaction and 
 preparation by hydrolysis, the albuminous matters, cellulose, and 
 fats are broken up into soluble nitrogenous compounds, fatty acids, 
 phenol derivatives, gases, and ammonia. In the second stage,, or 
 that of semi-anaerobic disintegration of the intermediate dissolved 
 bodies, a further formation of ammonia, nitrites, and gases takes 
 place. In the third stage, or that of aeration and nitrification, 
 ammonia and carbon residues are changed into water, carbon 
 dioxide, and nitrates. 
 
 A large variety of installations have been devised to secure 
 these really natural or biological changes in sewage ; though they 
 differ from each other in matters of detail, they all are the same 
 in principle. The majority of the installations in present use 
 embody the principle of dividing, more or less, the whole process 
 of sewage purification into two stages; namely, a first stage 
 identical with that referred to above, which is chiefly anaerobic 
 and secures the liquefaction of the solids, and a second or aerobic 
 process which embraces the second and third stages of Rideal 
 and establishes nitrification of the previously unstable products. 
 After a preliminary screening to remove paper and other coarse 
 material from the sewage it is passed into a small detritus pit, to 
 the bottom of which fall stones and other heavy adventitious 
 matter; the first stage of the purification is then secured by 
 passing the sewage into a septic or digesting tank of a size 
 sufficient to hold 24 hours' flow of sewage. From this tank the 
 sewage is then made to pass slowly into or on to one or more 
 filter beds, in which aeration or nitrification takes place and so 
 completes the second stage. The earlier types of septic tank 
 were closed tanks, but experience showed that when sewage is 
 allowed to flow slowly through an open tank, a thick spongy 
 scum gradually covers the surface. This scum provides a cheap 
 roof which preserves the heat in the sewage, promotes bacterial 
 action, and tends to prevent the production of smell. Moreover, 
 the action of these open tanks is just as efficient as the closed 
 ones and are also cheaper to construct. The action of the septic 
 or anaerobic tank leads to the digestion of some 40 per cent, of 
 the suspended solids of sewage, with the result that the tank 
 effluent rarely contains more than 20 parts per 100,000; also, the 
 stability of the organic solids of the sewage is reduced rapidly 
 by a short stay in a tank and subsequent purification much 
 facilitated. 
 
 A typical installation is that suggested originally by Cameron 
 of Exeter and shown in Fig. 53. In it the sewage first passes 
 through a tank of about one day's sewage capacity, from which it 
 overflows in accordance with the rate of flow of the sewage. Thus 
 
2/2 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 it may be said all sewage is in the tank for 24 hours. Digestive 
 changes take place in the sewage within this tank as the result of 
 anaerobic bacterial action, which is favoured by the darkness, the 
 absence of air, and the comparative stillness at which the sewage 
 is maintained. Under these influences much of the solid matter 
 is rendered soluble and dissolved. After passing thus slowly 
 through the tank the more liquid portion of the sewage passes 
 away in a thin stream along an open trough or aerator, over the 
 edge of which it flows, and is ultimately discharged on to filter- 
 beds. At this stage the sewage appears as merely dirty water, 
 but having some offensive smell which is given off as the liquid 
 passes over the filter-beds. The filter-beds consist of clinkers or 
 coke breeze, in which the aerobic and nitrifying organisms attack 
 the sewage * constituents and complete the work of organic dis- 
 integration commenced in the septic tank. The sewage is passed 
 on to the filters by means of an automatic gear, which allows them 
 
 Septic Tank N'l • ■ 
 i *-^. \ piers supporting Roof 
 
 '• StpHc Tank N°2 
 
 ,-^»^pB v»i.l ' ' ' ' V ' ' ' ' ' 
 
 ftotn ^ffi^'O^Tffy IriJet ^Inspection We/i 
 
 Store*" Valve XJ ,f, • * " - ? - • • • - • • 
 
 Ovinia,' Chambir W Wet Stphc Tank f,"3 
 
 ; " * Sept'c Tank 'n°4 ' 
 
 I II ■■ Mil I ..I 
 
 Filler N'i 
 
 Alter N'4 
 
 Discharge 
 
 rid in 
 
 Fig. 53. — Plan of a septic tank with contact beds instal'ation. 
 
 to be filled almost to their top surfaces and then to rest for a 
 period of two hours. This is why these filters are called " con- 
 tact beds," as it is during the period of contact with the material 
 in the bed that the nitrification of the sewage takes place. After 
 remaining quiescent for two hours, the sewage is slowly run off, 
 the beds emptied and allowed to rest for several hours. Actually 
 each filter-bed is filled up three times in twenty-four hours, and 
 this necessitates the provision of several such filters in even small 
 installations. The intermittent application of the sewage to the 
 contact beds insures a certain amount of aeration of the beds. 
 
 Filtrates or effluents from installations of this kind are bright, 
 clear, and stable. In the process the action of the anaerobic 
 bacteria is encouraged in the septic tank and carefully differen- 
 tiated from the subsequent aerobic action due to other organisms 
 in the filters. The periodical resting and aerating of the filter- 
 beds helps obviously to maintain the activity of the aerobic 
 bacteria. 
 
 Many modifications of the septic tank system have been 
 worked successfully all over the country, using an open septic 
 
BIOLOGICAL METHODS. 273 
 
 tank with double filtration through primary and secondary contact- 
 beds, or even aerating beds on to which the clarified sewage is 
 made to stream continuously by means of rotating sprinklers or 
 other devices, such as troughs and elongated water wheels pivoted 
 at the centre, or by travelling distributors. Aerating beds or 
 streaming filters continuously dowsed with sewage are more 
 expensive to construct and maintain than contact-beds, and are 
 more often a nuisance from flies. No matter what may be the 
 form or nature of a filter for sewage, it is necessary to realize that 
 they differ essentially from water filters, in that the latter act as 
 interceptors of micro-organisms, while the former act as a mesh- 
 work of bacteria preying actively upon the sewage. 
 
 The most notable departure from the simple septic tank as 
 originally conceived was Dibdin's subjection of the sewage to 
 primary anaerobic action in an open contact-bed filled with very 
 coarse material or rough ballast, in which the sewage remained for 
 two hours. The results by this method have been good, but these 
 rough primary contact-beds have the great disadvantage that the 
 upper layers rapidly become choked or clogged and constantly 
 require raking or ploughing to clean and aerate. From this 
 primary or roughing bed the sewage is passed on to secondary 
 contact-beds in which the matrix is of finer material. From 
 installations of this modified type, the best results have been 
 obtained when a greater area of coarse filter than of fine filter is 
 provided, and that the sewage is locked up for four hours in the 
 coarse beds and for two hours in the fine beds. 
 
 When the biological treatment of sewage was first introduced 
 it was assumed that a relatively short stay in the digestive or 
 septic tank would lead to a more or less complete solution of 
 the suspended solids and a removal of the sludge difficulty. 
 Prolonged experience has shown this to be far from the case, 
 as the majority of digestive tanks and even filter-beds also lose 
 in the course of a few months from 50 to 30 per cent, of their 
 cubical capacity owing to the deposition of undigested solids. 
 The recognition of this fact, particularly in the case of septic 
 tanks, where the deposition of sludge is often considerable, has 
 led to a variety of suggestions as to their size and construction. 
 The most favourable size for these tanks is now held generally 
 to be equal to one day's average flow of sewage, but in some 
 successful installations it is found to be considerably more, or 
 even much less. To avoid the undue washing oyer of this sludge 
 and scum from the digesting tanks on to the filters, the intro- 
 duction of scum-boards has been advantageous, but even in 
 regard to this detail, absolute uniformity in method and result 
 has not been secured. We find precisely the same state of 
 
274 TH E ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 affairs in regard to the filter-beds. There is no unanimity of 
 opinion as to whether the beds should be worked on the contact, 
 that is, intermittent, or the continuous system ; whether there 
 should be single, double, or even triple contact-beds ; of what 
 size and material the filtering material should be, or how the 
 sewage should be best delivered on to the filters. On each and 
 all of these points there is much divided opinion, the truth being 
 that there is no hard-and-fast rule, and that each class of sewage 
 must be dealt with according to its conditions. Multiple filters 
 are needed where strong or alternating weak and strong sewages 
 have to be dealt with, because a filter or contact-bed will effect 
 only a certain percentage reduction of the foul ingredients of the 
 sewage it receives, even when it has reached its maximum ripe- 
 ness or biological efficiency. It must be remembered that in 
 these cases we are dealing not merely with the reduction of 
 unstable material to ultimate products but the reduction of the 
 more stable organic matter to the unstable condition. This latter 
 is best effected by rest in a contact-bed or filter, and the former 
 by passage from one filter to another. There is a general 
 agreement that the best working depth for a filter-bed is from 
 4 to 8 feet, and that the 8 hours cycle of treatment of these 
 contact- or filter-beds gives the most consistent results, that is, 
 i hour to fill, 2 hours to rest full, i hour to empty, and 4 hours to 
 rest empty. If this cycle be maintained, the various types of 
 contact-beds can be worked at the rate of a million gallons per 
 acre per diem. 
 
 The difficulties arising from the often offensive effluent from 
 septic tanks, or even primary roughing contact-beds, led Dibdin 
 to advocate the preliminary treatment of crude sewage in tanks 
 or contact-beds in which the refuse of slate quarries laid in close 
 layers some 2J inches apart and supported on suitable slate 
 blocks furnished the necessary matrix in a tank about 4 feet deep. 
 In such an installation the crude sewage is best sedimented in 
 detritus tanks before passing to the slate bed, and if the effluent 
 from this latter contains much suspended matter it should be 
 made to pass through a shallow humus bed to deposit the fine 
 sediment before it is distributed to contact-beds or to aerating 
 continuous filters. The effective working of this slate type of 
 contact-bed appears to be a cycle of 1 hour filling, 2 hours 
 contact or holding up, and from 6 to 12 hours for emptying 
 and aeration, according to the strength of the sewage. Experience 
 shows that there is no necessity in ordinary cases to wash out the 
 deposited solids, but that as they become digested by the 
 organisms, the resulting product resembling earthy matter 
 gradually passes away with the liquid. The great advantage of 
 
BIOLOGICAL METHODS. 275 
 
 the slate beds in a satisfactory installation is that the primary 
 effluent is inoffensive and much less liable to create a nuisance on 
 secondary treament than is the septic effluent from a septic tank, 
 or even a coarse roughing primary contact-bed made of rough 
 ballast. 
 
 Recently, the employment of what is called l( activated 
 sludge " has been tried in sewage purification. The method is 
 one by which finely divided air is forced through sewage in 
 specially constructed tanks. The sludge is allowed to settle, the 
 supernatant fluid run off, and the tank again filled with sewage 
 and the aeration process repeated. The essence of the method is 
 that the sludge which accumulates acquires by degrees, under 
 aeration, the same properties as the slime which forms upon the 
 upper layers of a filter-bed, and,!when fully matured, this activated 
 sludge, if mixed in the proportion of one volume to from three to 
 five volumes of sewage in a tank by blowing air through the 
 mixture for a period of from two to six hours and then allowing 
 the clotted mixture to settle, yields a clear and stable supernatant 
 liquid or effluent equal in stability and inoffensiveness to that 
 obtained by other methods. We have no personal experience of 
 this method, but excellent results are reported to have been 
 obtained both as to quantity of sewage treated and the degree of 
 purification effected. 
 
 In all sewage installations on the biological principle certain 
 difficulties arise when certain trade effluents, especially acids and 
 brewery or tannery effluents, are passed into town sewage. These 
 materially upset the action of the essential micro-organisms con- 
 cerned in biological installations. The only remedy is to submit 
 these objectionable trade by-products to dilution or preliminary 
 treatment by lime before they are permitted to leave the premises 
 on which they are produced. The same remark applies to trade 
 effluents rich in fats or soapy matters. These need to be passed 
 through suitably constructed grease traps or treated with acid or 
 lime or aluminoferric. Another factor which needs attention in 
 all sewage purification installations is the question of capacity and 
 volume of sewage to be treated. The rule is that storm water 
 amounting to three times the dry weather flow of sewage must be 
 treated as sewage, and that any additional volume of storm water 
 up to six times the dry weather flow must receive treatment either 
 by means of an artificial filter or by passage on to land used for 
 no other purpose. Special filters of burnt ballast will usually deal 
 satisfactorily with 500 gallons of dilute sewage to each superficial 
 yard of filter area, or about 2 \ million gallons per acre per diem. 
 In all sewage installations, therefore, the local authority must 
 make provision for treatment of six times the dry weather flow. 
 
276 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 Comparison of Different Methods. — We cannot dogmatise 
 as to individual systems. The requirements of the sewage of 
 each and every place must be determined by local circumstances 
 and no hard and fast rules can be laid down as to whether a 
 system of contact-beds or a continuous filter installation is the 
 better. A much greater volume can be treated per square yard 
 by sprinklers than on contact-beds. Unsedimented sewage 
 should never be passed on to the percolating or sprinkling filters, 
 as the distributing arms speedily choke and a colloidal matted 
 growth forms on the surface of the bed, which impedes aeration. 
 Strong-smelling or putrefactive sewage should not be treated by 
 revolving distributors or fixed sprays, as the odour is intensified 
 by this mode of distribution. As regards matrix for filter-beds, 
 favourable reports are made as to ligno-carbon, a manufactured 
 product from peat, otherwise hard clinker from gasworks or from 
 refuse destructors for primary filters, and coke or pan breeze for 
 secondary filters appear to be the most suitable and readily 
 obtained' material. If the sewage is free from manufacturing 
 effluents of injurious character, and if a sufficient area of suitable 
 land can be obtained in a convenient position at a reasonable 
 cost, then irrigation is probably the most rational and economical 
 method of treatment. Many kinds of manufacturing refuse, if 
 admitted into sewers, interfere with the efficacy of land filtration, 
 either by clogging the soil or checking chemically the process of 
 oxidation ; this latter condition operates prejudicially also in 
 biological methods. In these cases, a preliminary purification by 
 precipitation is necessary, and it is probable that different forms 
 of chemical treatment will be found necessary for effluents of 
 different trades. 
 
 In all cases, the principle to be aimed at is the immediate 
 and complete removal of all kinds of refuse from the vicinity of 
 habitations in the most expeditious manner. The dry methods 
 do not answer this requirement, as the excreta is only removed at 
 intervals, and although deodorization may be complete, disin- 
 fection is not attempted. For a large population, therefore, some 
 system of water carriage is necessary. Having, therefore, sewage 
 to deal with, we must get rid of it in the least objectionable 
 manner. It must not be sent into rivers ; therefore, where land is 
 available, immediate application to the land, by irrigation or 
 filtration, is indicated. By land filtration, sewage can be purified 
 so that the effluent water may be permitted to run into any stream 
 or river, the water of which is not required for drinking purposes. 
 Little, however, of the manurial value is saved, the greater part 
 passing away in the effluent. Irrigation accomplishes all that is 
 done by filtration, with the further advantage that the whole of 
 
COMPARISON OF, DIFFERENT METHODS. 277 
 
 the manurial constituents of the sewage are returned to the soil, 
 which is fertilized by them. Both systems are, however, often 
 impracticable owing to lack of suitable land. 
 
 As regards the biological treatment of sewage, it can now be 
 stated definitely that the average results are as good as those 
 given by well-managed sewage farms, while the best results are a 
 long way better than those recorded of any sewage farm. A most 
 important feature in the biological treatment of sewage as com- 
 pared with any chemical process is that, when properly carried 
 out, it yields an effluent which is incapable of secondary putre- 
 faction. In this respect it may be regarded as the best solution 
 of the sewage problem, because the stability of an effluent which 
 has been mineralized by a biological process is absolutely secure. 
 We feel convinced that biological methods of treating sewage are 
 not only scientifically correct, but sufficiently efficient and 
 economical in their working as to quite preclude any reversion to 
 artificial methods, such as treatment by chemicals or electricity. 
 In formulating this opinion, we would emphasize the paramount 
 need of the biological treatment of sewage being carried out 
 logically and scientifically, and with due regard to the fundamental 
 principle that it needs to be conducted in stages; these are 
 (a) settlement and screening out of the grosser solids; (b) the 
 submission of the organic sewage matter to the action of both 
 anaerobic and aerobic micro-organisms under such conditions that 
 the maximum action of both groups of micro-organisms is secured. 
 The optimum conditions for the attainment of this maximum 
 action appear to be available by the suitable use of either closed 
 or open septic tanks, or rough primary contact-beds, or slate beds 
 followed by aeration either in secondary contact-beds, or by con- 
 tinuous streaming over suitably constructed aerated filters. The 
 factor which governs the bacterial population of a sewage filter- 
 bed is the area available for growth, and this may be increased 
 either by enlarging the cubic capacity of the filter or by sub- 
 dividing the filtering medium. Therefore, we may make this 
 generalization that, whether it be for a contact-bed or for a 
 continuous filter, the finer the matrix the less need be its depth, 
 and vice versa ; to this we may add, as the outcome of experience, 
 that primary contact-beds need to be made of coarser material 
 than secondary or tertiary beds. As affecting the successful 
 working of any sewage filter-bed, it is necessary that the bed 
 should be worked very slowly at first, in order to allow it to settle 
 down and the bacterial growths to form. In this way there will 
 be less danger of suspended matter finding its way into the body 
 of the bed, while the material is still loose and open. The work 
 thrown on the bed should not be increased until analysis of the 
 
27S THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 effluent reveals the presence of surplus oxygen, either dissolved or 
 in the form of nitrates. Analysis of the air in the bed may be 
 made usefully from time to time during resting periods. The 
 variations in capacity should be recorded carefully. If the 
 capacity is found to be decreasing rapidly, a period of rest 
 should be allowed. Long periods of rest should be avoided 
 during winter, as when deprived of the heat of the sewage 
 the activity of the organisms decreases. If necessary, the 
 burden on the bed should then be decreased by reducing the 
 volume of sewage applied daily, rather than by exaggerating any 
 intermittency of working. What form installations for sewage 
 treatment will take ultimately it is difficult to say but, doubtless, 
 further developments in the biological treatment of sewage will 
 occur. These probably will assume the form of a greater and 
 more exact control, not only of anaerobic, but also of aerobic 
 action. In other words, we shall be able to establish standards 
 for treating sewage in anaerobic beds or tanks for a definite time, 
 and subsequently treating it in aerobic beds containing particles 
 of definite size, and the flow of both sewage and air being so 
 controlled and regulated as to pass through the installation in 
 definite quantities. Exact work in these directions is greatly 
 needed as, at present, even the most successful installations are 
 empirical. 
 
 Sewage Effluent Standards. — Though modern methods are 
 great advances in the treatment of sewage, especially in destroy- 
 ing and rendering the organic matter soluble, the resulting 
 effluents are teeming with microbial life — in fact, in this sense, are 
 little different from the original sewage. Moreover, we know that 
 specific and pathogenic bacteria do survive passage through these 
 installations, and can find their way into the resulting effluents. 
 From these facts, it is evident that there are very grave risks 
 where sewage effluents are discharged into streams used for water 
 supply, or into water where water-cress is grown, or into estuaries 
 where oysters are laid. No general standard applicable to all 
 cases is possible or desirable. The best possible results must be 
 sought, having due regard to the nature of the sewage, and to the 
 conditions, volume, and uses of the stream which is ultimately to 
 receive it. Certainly no effluent from a biological sewage in- 
 stallation should be allowed to pass direct into any stream or 
 river. It should be made to pass through land before it reaches 
 the stream. The effect of an effluent upon a stream depends less 
 upon the absolute amount than on the nature and condition of 
 the organic matter contained in it. If an effluent is non-putrescible 
 on incubation its organic matter must have undergone a satis- 
 factory amount of fermentation, and consequently will remain 
 
SEWAGE EFFLUENT STANDARDS— CAMP SANITATION. 279 
 
 stable when discharged into a stream, and will take up little 
 dissolved oxygen from the water into which it is discharged. 
 Such an effluent will not create a nuisance and will not injure 
 fish life. 
 
 There being no satisfactory bacterial tests which can be 
 applied to a sewage effluent, it is customary to regard the follow- 
 ing conditions as the absolute minimum to be demanded of an 
 effluent before it can be regarded as satisfactory. It must be 
 clear, bright, and free from any odour of sulphuretted hydrogen, 
 it must not contain more than 3 parts of suspended matter per 
 100,000, and show no physical signs of putrefaction after in- 
 cubation for a week in a closed vessel at 8o° F. Formerly, some 
 importance was attached to the amounts of free ammonia, organic 
 or albuminoid ammonia, and chlorine as chlorides in a sewage 
 effluent. In the present day, these constituents are regarded as 
 of secondary importance and greater attention directed to its 
 capacity to absorb dissolved oxygen, the test to be applied to the 
 effluent with all its suspended solids. The absorption of dissolved 
 oxygen should be allowed to proceed for five days at a uniform 
 temperature of 65 F., and in this period the absorption of 
 dissolved oxygen should not exceed 2 parts of weight per 100,000 
 parts of effluent, this is equivalent to 14 c.c. per litre. Further, 
 the effluent should not contain more than 3 parts of suspended 
 solids per 100,000. In testing the condition of a stream which 
 has received a sewage effluent, the following provisional standards 
 are practicable. Since the average amount of oxygen found in 
 clean fresh water saturated with this gas is 7 c.c. per litre, or 
 1 part per 100,000, then a stream which has received a sewage 
 effluent may be considered to be very clean if no more than o*i 
 part of dissolved oxygen be taken up by 100,000 parts of the 
 water from the stream after incubation at 18 C. or 65 F., for 
 five days. If o'2 part be absorbed then it may be classed as 
 clean, if 0*3 part then fairly clean, if 0*5 part it is doubtful, and 
 if it absorbs 1 part per 100,000 then such stream is bad. On the 
 basis of this scale, if a river which has received a sewage effluent 
 does not take up more than 0*4 part of oxygen per 100,000 in five 
 days at 65 F. or 18 C, the water will be ordinarily free from 
 signs of pollution ; but if the absorbed dissolved oxygen be above 
 this figure, signs of pollution will almost certainly be apparent 
 coupled with a strong probability of nuisance arising. 
 
 Camp Sanitation. — The number of camps and temporary 
 lodgments which have been distributed over the country in 
 recent years demand some appreciation on the part of the 
 ordinary citizen as to their general sanitary control. In principle, 
 the sanitation of a camp is the same as that which concerns a 
 
So THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 group of ordinary dwellings; it differs therefrom mainly in the 
 circumstance that' its actual practice is essentially the use of simple 
 methods and simple material used in an intelligent way, 
 
 All camps may be regarded as so many improvised towns, in 
 which the tents and huts represent so many houses. The 
 selection of a camp site is dominated largely by the facilities 
 which exist for obtaining water; this is more particularly so in 
 regard to temporary camps, but where camp sites are likely to be 
 occupied any length of time the feasibility of bringing water to 
 the camp must be considered as much as taking the camp to the 
 water. Apart from the question of the water supply, the selection 
 of a camp site differs little from the selection of a site for an 
 ordinary house or group of houses. The only points which are 
 more particularly exaggerated are the need for a porous soil and 
 physical features favourable for rapid and easy surface drainage ; 
 in other words, choose areas which are not only dry but clean, 
 that is, have not been occupied recently for other encampments, 
 and are not fouled or in any way encumbered with the recent 
 filth of man and animals. 
 
 Although in army life, certain regulations exist as to the 
 manner and place of laying out various camps, it will be readily 
 understood that these are subject to constant variation, owing to 
 physical difficulties connected with the locality. These restric- 
 tions play a less dominant role in many camps of a quasi military 
 nature, or under circumstances where freedom of choice exists as 
 to siting and lay out. In camps composed exclusively of tents, 
 the chief danger lies in overcrowding in the tents. Due regard 
 is paid to this as much as possible, but often circumstances 
 compel the placing of the full complement of men in various types 
 of tent, with the result that the superficial space available for each 
 individual may be as little as it and rarely more than 20 sq. feet. 
 In camps of a more permanent nature, especially where huts are 
 available, the danger from overcrowding is more under control 
 and the floor space is never less than 50 sq. feet per man, with a 
 cubic space of 500 feet per man. It is a good rule, never to put 
 more than 8 or 10 men in a bell tent and not more than 24 men 
 in a hut. 
 
 Where tents are in use/the tent walls must be looped up daily 
 so long as the weather permits, so that the tent area may be dried 
 and freshened by air and sunlight. Even in cold and doubtful 
 weather the sides of tents should be tied up during the absence 
 of the occupants. All tents should be struck and their enclosed 
 ground area aired or sunned for a few hours every five days. In 
 a properly arranged camp, the intervals should be sufficient to 
 render the shifting of a tent to a new site possible. Where huts 
 
CAMP SANITATION. 28 1 
 
 are used, the doors and windows must be opened daily to permit 
 of aeration and the entrance of sunlight. The digging up or 
 excavating out of the soil within a tent area is unwise as impeding 
 cleanliness and ventilation ; if floor-boards are not available, then 
 the ground may be covered with either straw or a tarpaulin ; but 
 whatever is employed it must be turned out, aired and cleaned 
 daily. Blankets, bedding, and clothing must be sunned and aired 
 each day either by hanging on improvised supports erected 
 specially for the purpose, or by spreading on the sunny side of the 
 tent roof; the former plan is preferable, as it allows access of light 
 and air to both sides of the article. 
 
 On no account should men be encouraged or allowed to store 
 food in their tents or huts. If food must be retained by the 
 individual, every endeavour must be made to keep it in closed 
 tins or boxes so that neither flies 'nor dust may gain access to it. 
 All food remains, particularly if not likely to be utilized in a few 
 hours, should be either burnt or buried. Similarly, occupants of 
 camps should not eat their meals in the same tents or huts which 
 they use for sleeping or general shelter. Sometimes it is impossible 
 to arrange otherwise, especially in temporary or hastily formed 
 encampments, but in all well planned and well managed per- 
 manent encampments one or more marquees or huts are set aside 
 and used only as dining-rooms. 
 
 In camps of a permanent nature, arrangements are made 
 usually to bring the water supply by a pipe service into the camp 
 area and deliver from stand-pipes. Where this is the case, no 
 sanitary difficulties arise as a rule, except the risk that the very 
 facility with which water is available may lead to waste and the 
 soddening of large patches of ground around the delivery taps. 
 The exercise of common sense and initiative should remedy this 
 trouble, mainly by providing suitable surface drains to carry off 
 such wasted water or by penalizing the camp occupants to furnish 
 so many men daily to act as picquets or sanitary guards over each 
 stand-pipe. Such stand-pipes should be adjacent to kitchens 
 and ablution places but remote from urinals and latrines, unless, 
 of course, a water carriage system of sewage disposal has been 
 installed. This latter arrangement is, however, rare. Where 
 local water is the source of supply, care is needed to safeguard 
 its pollution by the camp occupants and to avoid waste. Men 
 and animals should not take their drinking water from the same 
 place on the banks of streams, the animals must invariably be 
 watered at a point down the current below that at which the men's 
 water is drawn. In camps dependent on a local source, the 
 water is carried usually from its source to the lines in tanks on 
 wheels or even by smaller vessels. In all cases, care is required 
 
282 THE ULTIMATE DISPOSAL OE REFUSE AND EXCRETA. 
 
 to keep these receptacles clean, and where water is kept stored in 
 camp the tanks, barrels, or other vessels must be protected from 
 dust and other contamination by suitable covers. Men should 
 fiot be allowed to drink direct from the taps of stand-pipes or of 
 water-tanks, or from the rims and spouts of other receptacles used 
 for carrying and distributing water. 
 
 The cooking of food in camps presents no serious sanitary 
 problems ; at best it must be rough and crude. The most im- 
 portant details which need attention are : (i) that the kitchens be 
 located well away from latrines, urine pits, or other receptacles for 
 refuse and garbage ; (2) all sullage water must be made to pass 
 into pits from which it can drain away along suitably dry trenches. 
 This waste water is greasy, and if allowed to pass direct on to the 
 soil soon makes a greasy quagmire covered with a scum which 
 attracts flies. Sometimes such sullage water may be poured into 
 specially placed tubs which are carted away periodically. If these 
 are in use, they must be kept covered and removed daily. Where 
 disposal of this greasy waste water depends on local absorption 
 by the soil, a useful plan is to fill the reception pits or preferably 
 the upper ends of the drainage channels with hay, straw or coarse 
 brushwood ; if the greasy water be poured slowly through these 
 coarse strainers the grease and other organic solids are entangled, 
 allowing the clearer liquid to run aw r ay. The brushwood, straw, 
 or hay, loaded with fatty matter, must be buried, or better still 
 burnt, daily and replaced by fresh material. The soakage pits 
 need watching so that they are not overworked. It is usual to 
 make a series and use them in turn for definite periods according 
 to the nature of the soil and the volume of greasy water to be 
 removed. Closely associated with the kitchens and food supply 
 is the system available for washing up cooking utensils, plates and 
 dishes. These details are often overlooked. For all camps, a 
 particular and separate washing-up place should be allocated. 
 This and the kitchen should be situated conveniently close to the 
 tent or hut in which meals are eaten, also provided with an ample 
 supply of hot water and a sufficiency of dish cloths to secure 
 always a clean and wholesome food service. No men who have 
 suffered from enteric or paratyphoid fever should be employed as 
 cooks or in the service of food ; such men as are so employed 
 should have been inoculated against enteric fever. The ablution 
 places must be provided with adequate surface drains, otherwise 
 they rapidly become sloppy, wet and dirty. Basins should be 
 available at a rate of 14 per cent, of men using the ablution place 
 and in addition bathing tubs for men wishing to have a bath 
 should be available at the rate of 4 per cent, of strength. Whether 
 a sufficiency of hot water can be made available will depend on 
 
CAMP SANITATION. 2S?, 
 
 circumstances, but in permanent camps there are no insuperable 
 difficulties in the way of its provision. 
 
 Kitchen refuse and the hundred and one things which go to 
 make up the ordinary refuse from camps must never be thrown on 
 the ground but always into special receptacles placed conveniently 
 for the purpose, such receptacles should be provided with covers. 
 Final disposal may be arranged for through a contractor, who 
 deals with it at his own cost and risk, or it may be buried in deep 
 pits or burnt. This latter method is the best and by means of 
 simple improvised incinerators made of bricks, stones, or grass 
 sods, arranged with plenty of access of air from below, the 
 disposal of this material by fire is not difficult. The process is 
 helped if the solid and liquid refuse be kept separate. The 
 place chosen for these incinerators should be outside the tent 
 or hut area. 
 
 The disposal of urine and excreta in camps is vital to the 
 sanitary interests of all, but if ordinary intelligence be exercised it 
 presents fewer difficulties than might be expected. In permanent 
 camps provided with a piped water supply, a complete water 
 carriage system of sewage disposal is the best, and in its general 
 design differs little from that explained as appropriate for houses 
 and other permanent buildings. When no such elaborate arrange- 
 ments can be made, reliance must be placed upon either a trench 
 system or a modified pail-midden system. Latrines, irrespective 
 of method or kind, must be located well away from kitchens and 
 preferably ioo yards from the outer limit of the tent or hut area. 
 For ordinary or more or less temporary camps the usual latrine 
 is a trench or series of trenches, provided or not with a seat. A 
 latrine trench 20 ft. long, 2 ft. deep, and 1 ft. wide is the common 
 allowance for each hundred men. These long trenches are 
 difficult to provide with a seat, unless boxed over. A more 
 preferable arrangement is to dig a series of short trenches in 
 parallel, across which the user straddles. Each such trench should 
 be 3 ft. long, 2 ft. deep and 1 ft. wide. Four of these trenches 
 suffice for each hundred men. A seat in the form of a stout pole 
 can be laid at right angles to the trenches, supported on forked 
 uprights. A back rest may be formed by a similar pole, but is 
 often omitted. The trenches in use must be surrounded by some 
 form of screen, also covered with a roof if possible, and the earth 1 
 dug out from the trenches well broken up and carefully piled 
 either at the back or at the side of the trench. All displaced 
 grass sods must be carefully stacked near by so that when the 
 trench is filled in these grass sods can be replaced and the fouled 
 area made neat and wholesome. Two or more spades or shovels 
 or trowels must be available within the screen and with these each 
 
284 THE ULTIMATE DISPOSAL OF REFUSE AND EXCRETA. 
 
 user covers his dejecta with a sufficiency of earth. Kicking the 
 soil in by the foot is certain to be a failure. Men must be made 
 to understand the necessity for covering their dejecta before 
 leaving the latrine. Failure to conform to this practice should be 
 made a matter of discipline. Each day the latrine trenches 
 should be filled in with earth, the whole pressed down and grass 
 sods replaced. New trenches will then be taken into use. Should 
 the latrine area be on a slope, it must be guarded on the upper 
 side by a shallow drain to carry off surface water and so safeguard 
 the trench contents being flooded out. 
 
 In some camps of a semi-permanent nature, it is better to 
 provide pail-middens placed under boxed seats and providing a 
 sufficiency of dry earth with scoops to enable each user to cover 
 his own faecal deposit. The disposal of the contents of these 
 midden pails is best carried out by burning in some simple form 
 of incinerator. Such an incinerator should be placed close to the 
 latrine, and if the dejecta be mixed with sawdust, shavings, or dry 
 camp refuse it can be burnt readily. Failing destruction by fire, 
 the pail contents must be dealt with as in towns by hand and cart 
 removal for disposal on land. Water-closet or latrine seats in 
 camps need to be provided at rate of 6 per hundred men. 
 Urinals consist either of a pit or trench filled in when used 
 sufficiently, or special metal tubs are provided and the contents 
 removed by hand or cart and disposed of either into soakage pits 
 or poured on to land. Wherever possible, a water carriage system 
 of excreta disposal should be adopted in camps. It entails no 
 handling and no cartage of foul material, is largely automatic in 
 action, and reduces to a minimum the risks of infection by soiled 
 boots and flies. 
 
 CHAPTER VI. 
 
 PERSONAL HYGIENE. 
 
 By the term Personal Hygiene is meant the consideration of those 
 matters which concern the person's own health, and which relate 
 only to the individual himself or herself. It includes the discus- 
 sion of such subjects as Habits, Washing and Bathing, Clothing, 
 and Exercise. 
 
HABITS. 285 
 
 Habits. 
 
 Our habits may be either important aids to the promotion of 
 health and the lengthening of life, or they may be important 
 predisposing causes of disease. 
 
 Eating and Drinking. — It is of the greatest importance that 
 all young people be taught to chew their food carefully and to 
 eat slowly, as quick eaters generally suffer from indigestion later 
 on in life. The excessive use of condiments and spices is a habit 
 not to be encouraged. In youth we may eat plentifully, but in 
 old age we should eat sparingly. The evils of intemperate habits 
 and excess in alcoholic drinks are incalculable. Alcohol, besides 
 rendering man's capabilities for work less, deadens the activity of 
 the mind, interferes with the oxidation of waste matters in the 
 blood, and so alters the character and function of the internal 
 organs, particularly the liver and kidneys, that disease and death 
 therefrom are, in most cases, the early result for those who habitu- 
 ally take alcohol in excess. 
 
 Smoking is another doubtful habit, and one for which there is 
 not the slightest reason or excuse under twenty-one years of age. 
 For elderly persons, or those in middle life, particularly when 
 engaged in much mental or other work, the use of tobacco often 
 soothes the mind and otherwise acts sufficiently as a restorative 
 to the exhausted or fatigued nervous system as to justify the con- 
 tinuance of the practice. 
 
 Sleep. — The habit of taking sleep regularly is essential to 
 health, for both body and mind need periodical rest, and it is 
 only during sleep that this is obtained. Children need more 
 sleep than grown-up people ; small children should sleep at least 
 twelve hours a day, young lads and girls about nine hours, and 
 adults about seven hours in a day. Night is the natural time for 
 sleep. If possible, all people should sleep upon beds and bed- 
 steads ; to sleep upon the floor and ground is frequently unhealthy. 
 Plenty of fresh air is wanted at night and during sleep ; hence 
 people should not sleep with the head covered up, neither should 
 they lie in draughts and cold currents of air ; the body needs to 
 be kept warm at night to avoid chills. All bedding should be 
 kept clean and fresh, as waste matters from the body stick to 
 them and, if allowed to remain dirty, give rise to ill health. 
 
 The regular removal of waste substances from the body is 
 most necessary for the preservation of health ; for if they are not 
 removed, they become re-absorbed into the blood, and there act 
 as poisons. Since the organs by which waste matters are removed 
 from the body are the lungs, the skin, the kidneys, and intestines, 
 it is important that all should early acquire habits suitable for 
 
286 PERSONAL HYGIENE. 
 
 keeping them in proper action. The chief agents in regulating the 
 action of the first three are cleanliness and exercise ; with regard 
 to the last, the formation of a regular habit early in life is essential, 
 while exercise also helps the action of the intestinal canal. 
 
 Another good and important habit is that of cleansing the 
 teeth ; this should be done at least twice a day ; such a practice, 
 besides keeping the mouth clean and sweet, helps to preserve the 
 teeth themselves, and prevent their decay. For those teeth which 
 are decayed, much can be done by going to the dentist, and 
 having the decayed parts cleaned out and " stopped," or plugged, 
 so as to avoid any further extension of the decaying process. 
 
 Washing and Bathing. 
 
 If the skin is not kept thoroughly clean, the dead scales of it, 
 which ought to be removed, collect upon the surface and, with 
 dirt, block up and check the proper action of the many glands 
 contained in the skin. If the skin does not do its work properly, 
 more has to be done by the lungs and kidneys ; and these, if 
 they have too much to do, are likely to get diseased from over- 
 work. The free use of water is an excellent stimulant and tonic 
 to the skin ; but to remove dirt and grease and for purposes of 
 cleanliness, bathing or washing without the use of soap and 
 friction is useless. 
 
 Soap is either a potassium or sodium salt of one of the fatty 
 acids, stearic, oleic, palmitic acid, etc., produced by the action 
 of either potash or soda upon the fats. Potash soaps are very 
 deliquescent, retaining so much water as to form often a soft jelly : 
 of this kind is soft soap. Soda soap retains little water, and 
 readily hardens when exposed to the air, constituting hard soap. 
 Ordinary soft soap is largely made from whale or seal oil, and the 
 drying vegetable oils, such as linseed oil. Ordinary hard soaps 
 are commonly made from tallow and the non-drying vegetable 
 fats and oils, their hardness being in proportion to the stearic and 
 palmitic acid which they contain. Mari?ie soap, or soap used for 
 washing in sea-water, is made by the action of potash or soda 
 upon cocoanut oil. 
 
 Yellow soap is made by a mixture of resin with tallow and 
 palm oil, or with a grease stock consisting of kitchen and bone fat. 
 It is very firm, somewhat rough, and often translucent. Toilet 
 soaps are varied in quality. They are commonly made from lard, 
 beef marrow, or sweet almond oil, and after repeated refinings by 
 melting and powdering, finally scented with some perfume, such 
 as the oil of roses, bergamot, mallow, lavender, verbena, rose- 
 mary, thyme, etc. Their colouring depends upon special pigments 
 added to them. What is called Brown Windsor is an inferior 
 
BATHS. 287 
 
 soap of this kind, being made from the residue of refuse fats, 
 scented with nitro-benzene or artificial oil of bitter almonds. 
 
 Glycerine soap is merely ordinary soap, to which glycerine has 
 been added. The transparent soaps are made by drying ordinary 
 soap in a stove, and then dissolving it in hot alcohol \ subsequently 
 this solution is filtered, the alcohol distilled off, and the residue 
 run into moulds. Silicated soaps are ordinary soaps mixed with 
 solutions of soluble glass or silicate of soda. These mixed soaps 
 have exceptional cleaning properties, owing .to the quantity of free 
 alkali which they contain. Some of the so-called silicated soaps 
 are mere mechanical mixtures of silicious substances, such as fine 
 sand or fullers' earth, with ordinary soap ; these are comparatively 
 worthless. 
 
 Baths. — Water being a very much better conductor of heat 
 than air, it rapidly abstracts heat from the body if much below 
 the temperature of the latter, which is roughly 98 F. Owing 
 to their physiological action being mainly dependent upon their 
 temperature, the following classification of baths has been 
 made : — 
 
 1. Those in which a healthy person feels neither hot nor cold ; 
 these are often called indifferent baths. Their temperature varies 
 from 88° to 98 F. Some indifferent baths may be called warm 
 baths, while those intermediate between warm and cold are often 
 spoken of as tepid baths. 
 
 2. Cold baths, or those in which a healthy person feels cold. 
 Their temperature varies from 32 to 6o° F. If the bath is 
 only moderately long and not very cold, the body heat remains 
 constant, because the production of heat balances the loss. If 
 much prolonged, there is an actual loss of body warmth. Cold 
 baths greatly increase the tissue waste of the body. 
 
 3. Warm baths, or those in which a healthy person feels warm. 
 Their temperature may vary from ioo° to 103 F. A warm bath 
 increases the body heat by both imparting warmth to it and 
 preventing loss of heat from it. Some people, particularly the 
 Japanese, use very hot baths indeed. Unless one has been 
 gradually educated up to them, exceptionally hot baths should 
 not be employed. Vapour and Turkish baths are varieties of the 
 warm bath. The latter is practically the passing of a longer Or 
 shorter time in rooms at temperatures rising from ioo° to 200 F. ; 
 during this period, the action of the skin is vigorously encouraged, 
 and the body, after cleansing with soap and friction, gradually 
 hardened by sprayings of water passing from hot to cold, followed 
 by a cold plunge and subsequent rest or detention in a cool room. 
 
 A short bath is usually followed by a sense of well being, due 
 to the increased activity of and removal of waste products by the 
 
288 PERSONAL HYGIENE. 
 
 internal organs, consequent on the contraction of the superficial or 
 cutaneous blood-vessels. The feeling of warmth, which so com- 
 monly ensues, and ought always to ensue, after leaving a cold bath, 
 is probably to be explained by a reactionary dilatation of the 
 vessels of the skin after their original contraction. If a bath has 
 been too prolonged, or the person be at all enfeebled, there may 
 be no subsequent feeling of warmth after bathing. All bathers, 
 therefore, should take care not to in any way prevent the re- 
 actionary dilatation of the superficial or cutaneous vessels, by 
 either remaining in a bath too long or using it at too low a 
 temperature. 
 
 Cold baths, if not too cold, are particularly enjoyable, on 
 account of the reactionary exhilaration which follows. Their 
 regular employment is specially favourable for training the capil- 
 laries to alternately contract and dilate, and thereby render 
 habitual bathers remarkably free from liability to catch cold. 
 
 It is a mistake to bathe either fasting or immediately after 
 taking a full meal ; and equally injudicious to do so when 
 exhausted by fatigue. The best time for a bath is either early 
 in the morning after a cup of tea or coffee and a biscuit, or an 
 hour or so after breakfast. Persons advanced in years, and those 
 in whom the circulation is weak, should neither attempt outdoor 
 bathing nor indulge in very cold baths at home ; in them the 
 resisting and rallying powers are often low, and reaction corre- 
 spondingly difficult to secure. A very hot bath, of ioo° to no° F., 
 is often less depressing than a warm one of a lower temperature, 
 as it stimulates both the skin and circulation. To avoid chills, 
 such very hot baths are best taken at night. The following table 
 indicates the approximate temperatures of water-baths, arranged 
 according to popular designations : — - 
 
 Very cold 32 to 5o°F. 
 
 Cold 51 „ 6o°. 
 
 Fresh 6i° „ 75 . 
 
 Tepid ........ 76 „ SS°. 
 
 Warm 89° ,, 99 . 
 
 Very warm to hot ioo° ,, uo°. 
 
 It must be remembered that no very precise division of baths 
 can be made, as no two persons are equally sensitive to the effects 
 of heat and cold. 
 
 Clothing. 
 
 The main objects of clothing are : (1) to protect the body 
 from cold, heat, wind, and rain ; (2) to maintain its warmth, 
 protect it from injury, and also to adorn it. The chief materials 
 
CLOTHING. 
 
 289 
 
 used for clothing are derived from animals and vegetables. From 
 the animal world we get wool, fur, leather, feathers, and silk ; 
 while from vegetable life we draw cotton, flax, jute, hemp, coir, 
 indiarubber, and guttapercha. 
 
 Wool is a modified form of hair obtained from sheep, 
 goats, camels, and other animals. Wool fibres (Fig. 54) have 
 on their surface fine imbricated scales, which run in one 
 direction, and give it a serrated or toothed appearance when 
 
 Fig. 54. —Wool under the microscope, taken from white flannel. 
 
 examined under the microscope. Wool is soluble in caustic 
 alkalies, while vegetable fibres are not so. The wool from the 
 Angora goat is known as mohair, and is largely used in the making 
 of plushes, velvets, astrachans, and other fancy fabrics. Alpaca 
 comes from the Peruvian sheep, a kind of llama. It is a very 
 fine silky wool, and greatly used for shawls and umbrellas. Cash- 
 mere is a specially soft and fine wool from the Thibet goat ; it is 
 very expensive and difficult to get. Camel's hair is really a fine 
 wool ; it is now chiefly met with in the underclothing of Jaeger. 
 Wool is largely used for the making of flannel, cloth, blankets, 
 worsteds, and knitted goods. Felt is really wool made up without 
 either weaving or spinning, the whole holding together simply 
 by the cohesion of the serrated fibres. 
 
 Wool is the best material for underclothing ; it conducts heat 
 badly, and while absorbing moisture readily, gives it off slowly, so 
 that far less cooling is produced by evaporation from the woollen 
 garment than from any other. It has the disadvantage of harden- 
 ing and shrinking on washing. 
 
 Furs. — These are the skins of certain animals from cold 
 
 L 
 
29O PERSONAL HYGIENE, 
 
 countries, which have, in addition to their long " overhair," a 
 dense hairy covering called fur. The chief are bear, seal, chin- 
 chilla, ermine, and Russian sable or marten. Fur is often used 
 for making felt ; hat felts are chiefly made by compression under 
 heat and moisture of the fur from horses and rabbits. The 
 coarser felts used for carpets are made from cow-hair. 
 
 Leather. — The skins of animals, if appropriately prepared by 
 tanning, tawing, or shammoying, are rendered tough, yet soft and 
 fit for use by man as clothing. The chief skins so used are those 
 of the ox, sheep, horse, and goat. Tanning is the steeping of a 
 skin in an infusion of oak bark or other substances rich in tannic 
 acid. By this process, insoluble tannates of the gelatin and 
 albumin of the hides are formed. To be properly carried out, 
 tanning takes nearly a year. Tawi?ig is the same process as 
 tanning, except that mineral astringents such as alum and 
 bichromate of potash are used in place of the vegetable product, 
 tannic acid. Tawing is more rapid, but yields an inferior and 
 harsher leather than tanning. Shammoying is the impregnating 
 of a skin with fish oil ; it is chiefly applied to light skins, and is 
 the process by which chamois leather is prepared. 
 
 Feathers are not much used for actual clothing, but rather as 
 ornaments. Their employment is still considerable for stuffing 
 pillows and beds. These latter, if not made too soft and luxurious, 
 are quite as healthy as any other bed. 
 
 Silk. — This is the strong fibre produced or spun by the 
 caterpillar or larval stage of certain moths. The silk threads are 
 formed in two small glands situated on the under part of the 
 body and opening by a duct on the lower lip; the silk serves as 
 a protecting sheath or covering, called a cocoon, for the silkworm 
 when about to assume the chrysalis stage. The silk thread so 
 ejected by each worm and wound into a cocoon, measures some 
 4000 yards in length and consists of two fine filaments, one from 
 each gland, laid side by side and agglutinated together into a 
 single thread or fibre. The best silk is produced by the larva 
 of the moth called Bombyx ?nori, or Chinese silk-moth. Other 
 kinds of silk are spun from other silkworms closely allied to the 
 B. mori. There are the B. texto?- and B. fortunatus t common 
 in Bengal ; the B. crcesi, found in Madras ; the B. arracanensis, 
 met with in Burmah; and the B. sitiensis, belonging to China. 
 All these are mulberry feeders. The caterpillar of another moth 
 called Aiitheraia pemyi, found in Mongolia, and which feeds on 
 oak leaves, spins the kind of silk known as tussur silk. The 
 A, mylitta is another variety of the tussur silk-moth, common in 
 India. It feeds on bher trees and other shrubs. Similar moths 
 are found in Assam and Japan. 
 
SILK— COTTON. 
 
 ! 9* 
 
 The silk fibre (Fig. 55) consists of a central core or fibre, 
 covered with a waxy and albuminous colouring matter. Micro- 
 scopically, silk fibres are structureless and glass-like, usually 
 measuring some guoo mcn thick, and without surface markings or 
 scales. Silk is insoluble in water, alcohol, and ether, but dissolves 
 in very strong alkalies, mineral acids, and acetic acid. It is 
 readily distinguished from wool or other animal fibre by the action 
 of an alkaline solution of lead oxide, which, owing to the presence 
 of sulphur in wood, darkens it, but does not affect silk. Silk is 
 distinguishable from vegetable fibres by being stained yellow by 
 picric acid, which they 
 are not. The average 
 cocoon yields some 500 
 yards of workable silk, 
 which in its manufac- 
 tured form is either 
 reeled or spun silk — this 
 latter being prepared by 
 carding or spinning from 
 the waste and spoiled 
 cocoons. During its 
 manufacture into fabrics, 
 silk fibre is largely 
 altered, expanded, 
 weighted, and dyed by 
 various reagents, notably 
 salts of tin and iron, 
 which render the term 
 " silk," as applied to 
 
 actual articles of clothing, a more or less conventional expression 
 of what something is meant and ought to be. Silk is mainly used 
 in the manufacture of satins, silks, plushes, velvets, ribbons, crape, 
 and in a few woollen goods to give them lustre. Silk is very 
 absorbent of moisture, and is a non-conductor of electricity. 
 
 Cotton is the downy hair of the seeds of plants belonging to 
 the family Gossyftitim, of the order Malvaccce. The cotton fibres 
 consist mainly of cellulose, and vary from a half to one inch in 
 length. The fibres are freed from the seeds by machinery, and, 
 after being cleaned and spun into yarn, are woven into fabrics, 
 which, after being bleached, are " finished " for the market. This 
 finishing process usually involves mangling, starching, and damp- 
 ing, and often includes filling up the interstices between the fibres 
 with compounds to give weight and a false appearance. Cotton 
 is largely made up into sheeting, calico, towelling, jean, fustian, 
 velveteen, flannelette, and paper. When mixed with wool, it 
 
 Fig. 55 —Silk from a silk thread. 
 
292 
 
 PERSONAL HYGIENE. 
 
 constitutes the merino of vests, socks, and many fancy materials ; 
 
 it is also mixed with silk or the cheaper kinds of silken goods. 
 
 Cotton filaments 
 (Fig. 56) average about 
 10*00 inch thick, are flat 
 and ribbon-like, and 
 always recognizable by 
 being twisted. Cotton 
 is very durable, does 
 not shrink when washed, 
 absorbs moisture badly, 
 and rapidly conducts 
 heat away. On this 
 account it is ill-adapted 
 for under-garments next 
 the skin, as, if perspira- 
 tion be present, it readily 
 induces chill. What is 
 called " cellular cotton " 
 is merely an ordinary 
 
 Fig. 56. — Cotton from flannelette. 
 
 cotton fabric with larger interspaces than usual in its texture. 
 These being filled with air, which is a bad conductor of heat, 
 
 cause this material to be 
 somewhat warmer than 
 the ordinary cotton, and 
 a greater protection to 
 the body against sudden 
 changes of temperature. 
 Similar advantages at- 
 tach to " Airlin " and 
 the various " mesh fab- 
 rics " now in the market. 
 Flax is a fibre ob- 
 tained from the stalks 
 of a plant called the 
 Linum usitatissim um, 
 which grows to a large 
 extent in Russia and 
 Ireland. The seeds are 
 the familiar linseed, 
 from which the meal of 
 which poultices are made is prepared, and, too, from which 
 linseed oil and cake, the cattle food, are produced, The stalks, 
 after being allowed to ferment or rot on the ground in the damp, 
 are beaten and combed until something like 6 per cent, of sale- 
 
 Fig. 57.— Linen, from table-cloth of Irish linen. 
 
INDIARUBBER. 293 
 
 able flax fibre is obtained from the plant. The flax fibres (Fig. 
 57), when seen under the microscope, are marked by transverse 
 striae at regular intervals ; they are not flat like cotton, but more 
 like silk, only they show a fibrous and jointed structure which 
 is not met with in silk. Flax is much more expensive than cotton, 
 and is used chiefly for the manufacture of linen, cambric, and lawn. 
 Linen resembles cotton in being a good conductor of heat and a bad 
 absorbent of moisture. It is in many respects even inferior to cotton 
 for underclothing, but from its smoothness and lustre is unequalled 
 as a material for collars, cuffs, and shirt-fronts. Weight for weight, 
 flax fibre is stronger than cotton, in the ratio for single yarn of 3 
 to i*8, for double yarn as 3 to 2-25, and for cloth as 3 to 2*1. 
 
 Jute is a brittle and very hygroscopic fibre obtained from the 
 Cor chorus capsularis, a plant growing chiefly in Bengal. Jute is 
 not much used for clothing except as an adulteration of silk and 
 in the making of false hair ; it is chiefly employed for coarse 
 fabrics such as mats, cheap carpets, sacking, curtains, and table- 
 covers. It is used also as a backing for floorcloths. 
 
 Hemp is another fibre not much used in European countries 
 for clothing. It is a coarse fibre, prepared from the stem of the 
 Cannabis safiva, a plant growing in Europe, Asia, and America. 
 It is prepared like flax and jute, and chiefly used for rope, yarn, 
 canvas packing, and sail cloth. The Indian plant yields a 
 narcotic drug, while hemp-seed is a popular food for birds. 
 
 Coir is a coarse, tough, harsh, yet light fibre obtained from 
 the husk of the cocoanut. It is rarely used for clothing, but 
 largely so for making mats, brushes, and ropes. 
 
 Indiarubber enters largely in the present day into the constitu- 
 tion of our clothing, chiefly because it is elastic and impermeable 
 to water. Under the name of caoutchouc, it is the milky juice 
 of several plants growing in Africa, Asia, and South America. 
 Caoutchouc is a somewhat complex body, dissolving in chloro- 
 form, ether, petroleum, benzene, and carbon disulphide. Freezing 
 impairs its elasticity, while great heat softens and melts it. Fats 
 also destroy it. When steeped in melted sulphur at 140 C., 
 caoutchouc becomes vulcanized. Macintosh cloth is merely a 
 cotton or silk fabric covered, layer by layer, with a solution or 
 paste of caoutchouc. Guttapercha is, like indiarubber, the juice 
 of certain trees; but these grow only in the Malay peninsula. 
 Excepting as boot soles, guttapercha is little used in clothing. 
 
 Warmth and coolness, or the power of maintaining the body 
 heat at its normal height, being the most important property of 
 all dress materials, it follows that our choice of clothing will 
 depend largely upon this feature. How far a given clothing will 
 give warmth depends upon its material, its texture, number of 
 
294 PERSONAL HYGIENE. 
 
 layers, and its colour. Owing to fabrics conducting heat in the 
 following order from highest to lowest, namely, linen, cotton, silk, 
 feathers, fur, and wool, it follows that wool, fur, and feathers are 
 the warmest materials, then silk and cotton, while linen is the 
 coolest. The more readily a material conducts heat, of course, 
 the cooler it feels. This heat-conducting property is mainly 
 proportionate as to how close it is woven, and as to how little air 
 it contains. On this account, all soft, furry fabrics, no matter 
 whether of wool or cotton, always feel warmer than the closely 
 woven, smooth-surfaced silks and linens. In the same way, the 
 more layers of clothing there are, the more layers of air there are 
 retained between them. The influence of colour is dependent 
 upon the heat-absorbing powers of that colour. White absorbs 
 heat the least, and is consequently the coolest; then comes 
 yellow, red, green, blue, and black. It is obvious this effect of 
 colour can only be of influence when outside, and that the 
 popular idea that red flannel, when worn next the skin, or as 
 part of an undergarment, is warmer than white is imaginary. It 
 is a mistake to wear coloured clothing next the skin, as not 
 unfrequently the dyes are poisonous, and, coming off, give rise to 
 skin diseases. 
 
 While affording warmth, protection from cold, wet, and injury, 
 clothing should always be so made as not to in any w r ay impede 
 natural movements, nor unduly constrict any part of the body, nor 
 be needlessly heavy, and also not afford unnatural support. The 
 more we analyze the common forms of clothing, the more we see 
 that their main faults are in the direction of impediment, con- 
 striction, and weight. This is particularly emphasized in the case 
 of long and close-fitting skirts, tight sleeves, stays, garters, bands 
 round the waist and neck, ill-fitting gloves, hats, and boots. 
 Many of these defects and faults would be obviated if people 
 would remember that (i) no article of clothing should be either 
 so tight as to interfere with the circulation, or so shaped as to 
 change the natural outline of any part of the body; (2) no 
 garment should contain more material than is actually necessary ; 
 (3) all garments requiring suspension should be suspended directly 
 or indirectly from the shoulders or hips. 
 
 It is probably in the attire of children attending echool that 
 the greatest need of a neat hygienic dress is manifest. For girls 
 we would suggest that each should wear a flannel chemise, blue 
 serge knickerbockers fitted to the waist with an elastic band, and 
 no stays of any kind. Next we would suggest a woollen jersey, 
 and an overdress with shoulder straps fastened into the waist with 
 a loose belt. In summer the jersey might be left off, and a cotton 
 blouse substituted. For out-of-doors, probably a flannel hood 
 
EXERCISE. 295 
 
 would be the best head-covering in winter, while in summer a 
 head-covering is hardly needed in our climate. Such a dress as 
 this would be not only neat and healthy, but by its smartness 
 would raise the moral tone and help to give the self-respect which 
 is so often lacking in children. 
 
 When possible, underclothing should be of wool in this 
 country; in the tropics this is too heavy a material, and linen or 
 cotton shirting is more generally suitable. 
 
 Probably no article of attire is more faulty than the boot. A 
 properly made boot should fit the foot accurately ; the great toe 
 should be in a straight line with the inside of the foot ; the shape 
 of the sole of the boot should be taken by drawing a pencil round 
 the outline of the foot when the weight of the body is resting on 
 the foot, as in standing, so that the sole may be big enough to 
 support the fully expanded foot; the material should be of soft 
 and flexible leather ; even when new, the wearer ought to be able 
 to move all the toes with freedom in the boot ; the heel should 
 be broad and low. The stocking or sock should, whenever 
 possible, be of a woollen material or a mixed material in which 
 wool predominates. If no sock be worn, the boot needs to be 
 high and close-fitting round the ankle, so as to prevent dust and 
 stones getting into the boot. The sole of a boot should be wider 
 than the foot, and if the boot is meant for hard wear, the excess 
 of breadth in the sole should be considerable, so as to serve as a 
 protection against loose stones. 
 
 Exercise. 
 
 It may be said with truth that the chief condition of health is 
 exercise in the open air, and those who have the most of it are 
 the healthiest. The desire for physical exertion and muscular 
 exercise is a natural instinct ; the very restlessness of the young 
 child and of school children shows this. Our bodies possess the 
 peculiar attribute that the more they are used, within reasonable 
 limits, the stronger and more vigorous they become. Every one 
 is familiar with the fact that a disused muscle wastes, becomes 
 fatty and wanting in blood, whereas one which is judiciously 
 used and exercised, grows, thickens, and becomes in every sense 
 stronger. But mere exercise involves not only growth and 
 development of the ordinary muscles of the limbs, it means also 
 the healthy use of the heart muscle, of the muscles of respiration, 
 of the muscular tissue of the arteries, and of the muscular elements 
 of all parts which are capable of movement. To these must be 
 added an increased activity of the brain and nervous system, 
 along with a stimulation of both secreting and excreting organs. 
 
2g6 PERSONAL HYGIENE. 
 
 Upon the circulating system, the effect of exercise is to rapidly 
 increase the force and frequency of the heart's action with a 
 consequential augmented flow of blood throughout the whole 
 body. A healthy heart, during moderate exertion, though often 
 beating rapidly and forcibly, does so regularly and equally ; but if 
 embarrassed, or the exercise be severe and prolonged, its pulsa- 
 tions may become small, quick, unequal, and irregular. A 
 deficiency of exercise leads often to a weakening of the heart ; 
 but, on the other hand, exercise or unaccustomed exercise, 
 suddenly and long continued, may lead to palpitation, valve 
 disease, or other heart affections. These may be usually obviated 
 by careful training and judicious rest. Sudden and violent 
 exercise should be avoided by those with diseased hearts, and by 
 those advanced in years, as in them often the circulation is unable 
 to suddenly adapt itself to the new conditions set up. 
 
 On the lungs, the effects of exercise are to not only increase the 
 rapidity of breathing, but also to considerably increase the amount 
 of air inspired and the carbon dioxide expired. During exercise, 
 the elimination of carbon is enormously increased, a fact which 
 explains the instinctive desire of men making exertion and not 
 restrained in the choice of food, for the various fats and sugar 
 with a small amount of starch. When exercise is excessive or 
 badly arranged, the circulation through the lungs may become im- 
 peded and the breathing laborious. The knowledge of this fact 
 suggests the need to watch the action of the lungs of all men being 
 trained for prolonged exertion. 
 
 Under exercise, the voluntary muscles grow harder and be- 
 come more responsive to the will. If continuously over-exercised, 
 their growth may change to actual wasting, due to damaged 
 nutrition of their fibres, following either the accumulation in 
 them of the products of their own action, or the exhaustion of 
 their supply of oxygen ; possibly both. Provided it be not pushed 
 to such an extreme as to leave no time for cultivation of the mind, 
 there can be no doubt but that exercise is quite consistent with, 
 and eminently favourable to, high mental attainments and activity. 
 The effects of exercise on digestion are such that it stimulates a 
 desire for meat, fat, and salt, and in a less degree one for carbo- 
 hydrates. The abdominal viscera act more vigorously, and the 
 whole digestive processes are increased. The actual amount 
 passed by the bowels during exercise seems to be slightly 
 lessened, possibly due to less water entering the intestines. 
 
 Owing to the action of the skin being so much increased 
 during exercise, the water and chloride of sodium of the urine 
 diminishes; on the other hand, the uric acid, pigment, and 
 sulphuric acid are augmented. The urea, however, is little 
 
EXERdSE. 297 
 
 affected; while the actual total nitrogen excreted is, if at all 
 increased, only so in the period of rest succeeding exertion. 
 
 The exact amount of exercise which a person takes is entirely 
 a matter of individual decision ; while what amount a healthy 
 adult should take is not easy to fix, as a hard-and-fast rule 
 would not fairly apply to all the varying degrees of health and 
 strength. In this connection a word of warning is advisable. 
 There is evidence that the modern craze for extreme and special 
 athletic exercises is often doing more harm than good. Many of 
 these athletes fall a prey to degenerative changes, tend to become 
 fat and generally to lose physical stamina. Moderate athletics 
 are to be encouraged, and in the form of Swedish system of 
 exercises are an excellent code by which to secure the gradual 
 development of all the body muscles. As regards ordinary 
 exercises, such as walking, it may be laid down as a working 
 axiom that so long as such amount or kind of exercise gives 
 pleasure it may be undertaken, but when such is clearly distaste- 
 ful or irksome it may be assumed that it is uncalled for. 
 
 Work is always expressed in units of weight lifted through 
 a unit of height ; as in terms of pounds lifted a foot, or tons 
 lifted a foot. A fair day's work for a man of average weight and 
 height is generally taken to be about 300 foot-tons, or the work 
 necessary to raise 300 tons one foot high ; this has been calcu- 
 lated to be equivalent to walking about 16 miles in a little over 
 five hours. A hard day's work is about 450 foot-tons, equal to 
 walking some 24 miles in eight hours ; and an extremely hard 
 day's work is from 500 to 600 foot-tons, equal to walking 26 to 
 32 miles in nine or eleven hours respectively. For average men, 
 engaged in sedentary occupations, not less than 100 to 150 foot- 
 tons of work or exercise should be performed each day, equal to 
 walking for two hours at a moderate pace, or equal to raising the 
 body-weight through some 500 to 600 yards in height. It is not 
 easy to say what the work done is in mental and office work 
 generally. These rules, it must be remembered, apply only to 
 healthy adults, and need to be much modified in the case of 
 young children, or those whose age or health prevents their 
 exercising their full powers. In children, much of their power 
 and energy goes in building up the growing body, and conse- 
 quently less exercise or work can be expected of them. Thus, a 
 child, weighing 80 lb., ought not to be called upon to do half 
 the work done by an adult weighing 160 lb., but something less, 
 probably in the ratio of the square of their respective weights. In 
 a similar manner, women should not be called upon to do as hard 
 or even harder work than the men. 
 
 No mention has been made of the internal work of the body, 
 
298 PERSONAL HYGIENE. 
 
 such as that of the heart, respiration, digestion, etc. This has 
 been variously estimated ; but adopting a mean, we get about 
 260 foot-tons for all the internal mechanical work; which, added 
 to the external labour, makes the demand, for the average person, 
 to be about \ of all the force obtainable from the food con- 
 sumed. 
 
 For the average man or woman walking on ordinary roads, 
 the work done is equal to ^ of the work done in direct ascent, or 
 that a man walking 20 miles on the flat, at 3 miles an hour, does 
 as much work as if he had raised his body through a mile in 
 height. The fraction ~ is the expression of the resistance due to 
 traction, and varies with the velocity at which the work is per- 
 formed ; being -^ for a velocity of r mile an hour, ^5 for 2 miles 
 an hour, ~& f° r 4 niiles an hour, and j% for 5 miles an hour. 
 
 When a man goes up a height, he raises his whole weight 
 through the height he ascends, and to compute the quantity of 
 work done we must multiply the weight by the height, and an 
 easy calculation changes this into the weight raised 1 foot. 
 
 The formula for the calculation of work done is usually written 
 
 (W + VV) x D . 
 
 thus: X C = foot-tons : in which W is the weight 
 
 2240 ' ° 
 
 of the person, and W is the weight carried, both expressed in 
 pounds; D is the distance in feet; C is the coefficient of resist- 
 ance or traction; while 2240 is merely the number of pounds in 
 a ton. The application of this formula will be more readily 
 understood from the following examples. 
 
 Let A and B be two men. A lifts a 10-lb. hammer, 4J feet 
 high, 12,000 times in eight hours. B, who weighs 10 stone, walks 
 14 miles on an ascent of 1 in 300 in six hours, carrying 30 lbs. on 
 his back. It is required to know which does the harder work, 
 and by how much. __ v .._, ^ to ^ 
 
 at „.ur 1 *.i_ r a IOX45 X I2000> 
 
 Applying the formula to the case of A, we set 
 
 •^ ' ° 2240 
 
 which, worked out gives 241 foot-tons of labour done in eight hours. 
 
 B's case is somewhat more complicated. It involves two 
 
 small calculations, one for the work done, had it all been on the 
 
 flat, the other for the additional labour involved in going uphill, 
 
 which is equivalent to lifting his own and load's weight a given 
 
 height. The sum of these two will give his actual work done. 
 
 Using the formula, we get B's work on the flat to stand thus, aftei 
 
 reducing the stones to pounds and the miles to feet — 
 
 (140 4- 30) x 14 X 5280 
 
 v ^ 7 - X oV = 280J foot-tons 
 
 2240 20 2 
 
 As the rise is 1 in 300, we get for the second part of the state- 
 
child's welfare and school hygiene. 299 
 
 ment, the lifting of the man's body-weight and load, a height of 
 
 14X5280 (140 + 30) x 246*4 
 
 — 3 = 246*4 feet, or — ^ 3—2 = 18*7 foot-tons. 
 
 300 2240 
 
 Then adding these two results together or 280*5 + 187 = 299-2 
 foot-tons as the work B does in six hours. 
 
 In attempting to compare B's work with A's, we must allow 
 for the fact that B does his in | the time that A took, or six hours 
 as compared with eight hours. Therefore, to obtain a fair com- 
 parison, we must multiply B's work of 299 foot-tons by 4, and 
 
 4 
 divide by 3 or 299 x - = 398 foot-tons of labour performed by 
 
 B, while A only did 241 foot-tons, or 157 foot-tons of work done 
 by B more than by A, if both had been working at the same 
 speed. 
 
 CHAPTER VII. 
 
 CHILD WELFARE AND SCHOOL HYGIENE. 
 
 The high rate of infantile mortality which prevailed in this 
 country for so many years directed attention to the lamentable 
 loss of life which was going on, and due largely to ignorance on 
 the part of mothers and their adherence to faulty methods in the 
 rearing of infants. The outcome of attention directed to this 
 matter resulted in the development of a powerful and efficient 
 movement known as " child welfare." The earliest step in the 
 movement was to provide in districts trained and experienced 
 women visitors to give advice and encouragement to mothers of 
 the poorer classes as to the proper methods of rearing their 
 children. The movement was much helped by the Notification 
 of Births Act, 1907, whereby the existence and location of young 
 infants was made readily available to sanitary authorities. 
 Material support being rendered by the central government, the 
 movement was soon adopted by the sanitary authorities, who then 
 formed child welfare centres and clinics. In the early days of 
 the movement, the work was confined mainly to infants, but its 
 success in controlling mortality was so marked that the present 
 aim of all complete schemes of child welfare is to control and 
 supervise the up-rearing of children not only during infancy but 
 also up to the age of five years. In recent years, the movement 
 has developed further and embraces the watching over of the 
 
300 CHILD WELFARE AND SCHOOL HYGIENE. 
 
 health of the expectant mother, of bringing to full term and safe 
 delivery of children whose lives were lost to the nation formerly 
 as the result of abortions and miscarriages. These efforts are 
 maintained by the provision of skilled attendants or midwives. 
 
 In this manner is the solution of the infant mortality problem 
 being reached. The machinery brought into play is extensive, 
 and aims at more than efficient domestic or municipal sanitation. 
 It means intelligent and painstaking motherhood fostered or 
 controlled by both paid official and voluntary women health visitors, 
 coupled with organized schools for mothers, consultation centres 
 for mothers, infant milk depots, the provision of cheap meals to 
 expectant and nursing mothers, clinics for mothers and infants, 
 and some hospital accommodation for expectant mothers during 
 pregnancy, and also for infants. To these provisions must be 
 added the assistance of one or more doctors to co-operate with 
 the health visitors. As a general rule, the smaller sanitary areas 
 can be served more economically and efficiently by a county 
 scheme than by separate schemes for each district, provided that 
 proper co-operation with the sanitary authority is secured. A 
 County Council can combine in one individual officer the duties 
 of health visitor, inspector of midwives, tuberculosis visitor, and 
 occasionally those of school nurse and mental deficiency visitor, 
 and thus save expense and time whilst securing also uniformity 
 of work and direction. Local authorities should, as a rule, aim at 
 securing a staff equal to one whole-time health visitor for each 
 500 births. It is, moreover, important that the visiting of 
 children be extended to school age, and that ante-natal visiting 
 should be undertaken. The work of health visitors may include 
 properly the visiting of cases of measles, whooping cough, and 
 diarrhoea in young children. 
 
 A woman is qualified to be a health visitor if she is (1) a 
 qualified medical practitioner ; (2) a nurse who has undergone for 
 three years at least a course of instruction in the wards of any 
 hospital or infirmary being a training school for nurses, and 
 having a resident medical officer; (3) is certified under the Mid- 
 wives Act, 1902 ; (4) has for a period of not less than six months 
 undergone in a hospital or infirmary receiving children as well as 
 adults, and having a resident medical officer, a course of in- 
 struction including subjects relating to personal hygiene, and 
 holds a certificate of the Royal Sanitary Institute for health 
 visitors and school nurses, or the certificate or diploma of the 
 National Health Society, or of any other body approved by the 
 Ministry of Health; (5) has in the service of any sanitary 
 authority or public body in England and Wales, discharged duties 
 similar to those of a health visitor, and produces evidence of 
 
CHILD WELFARE AND SCHOOL HYGIENE 30 1 
 
 competency ; (6) when the circumstances so require, a woman may 
 be appointed who holds none of the above qualifications (1 to 5), 
 but has a competent knowledge and experience of the theory and 
 practice of nurture, of the care and management of young 
 children, of attendance on women in and immediately after child- 
 birth, and of nursing attendance in cases of sickness or other 
 mental and bodily infirmity. In practice, the health visitors work 
 under the instruction of the medical officer of health of the area. 
 
 When it is remembered that about 3 per cent, of the total 
 births notified are still-births, the need of ante-natal clinics is 
 manifest. Further, since for every still-birth after the seventh 
 month of pregnancy there are at least four abortions between 
 conception and the seventh month, it follows that for every 
 100 children born alive some 15 have died in utero. This 
 means that the fatality among the unborn is higher than the 
 fatality of infants in the first year of life. If all women were 
 under skilled observation during pregnancy, it is probable that 
 about half the ante-natal deaths that,now occur could be prevented 
 and the number of infants born prematurely and of feeble consti- 
 tution could be much reduced. At least one-fourth of the 
 children who die in the first year of life die during the first week ; 
 most of these deaths and of those who die within the first three 
 months are due to ante-natal conditions of the mother and might 
 have been remedied by ante-natal attention. In any scheme of 
 ante-natal care there must be an ante-natal clinic, held weekly or 
 fortnightly at a recognized centre by a skilled gynecologist coupled 
 with home visiting of pregnant women by a trained health visitor. 
 The inquiries made by the health visitor should be entered on a 
 prematernity card and produced at the clinic for the information 
 of the doctor. The woman's visit to the clinic must be recorded 
 on the card, and the medical advice given or treatment recom- 
 mended. Subsequent visits to the woman at home by the health 
 visitor will be directed to see that the instructions are being 
 carried out, and that all proper steps are taken to prepare for the 
 approaching confinement. This action is materially helped by 
 the maternity benefit available under the National Insurance 
 Act, 191 1. 
 
 While much can be done by this ante-natal work, and also 
 by home visitation on the part of the health visitor whereby 
 observation can be made as to conditions, and the giving of sound 
 instruction to mothers as to the right way of nurturing their young 
 children, it is obvious that furthur advantages may be derived 
 from the provision of Infant Care or Child Welfare Centres to 
 which parents may bring their infants on certain afternoons. 
 Not only can the infant be weighed, but the recording of the 
 
302 CHILD WELFARE AND SCHOOL HYGIENE. 
 
 results be better and more expeditiously performed, but the 
 arrangement results in a saving of time for the health visitor. 
 Further, the establishment of a Centre allows of the temporary 
 assistance of a medical man to advise the mothers and help 
 the health visitor. In most large towns and populous centres, 
 schools for mothers or child-welfare centres have been estab- 
 lished. The Centre should comprise at least three rooms ; one 
 as a weighing- room for babies, one a waiting-room, and one 
 for the doctor. The centre must be convenient of access for 
 the poorer class of mothers, and the consultations should be held 
 in the afternoon one day a week throughout the year. Records 
 must be kept of the attendances, with the weight of the babies, 
 and the instructions or advice given in each case. Treatment 
 of simple ailments can be given on the spot, or the mother 
 referred to a hospital, dispensary, or medical practitioner. 
 Advantage may be taken of these visits to the Centre to give 
 informal talks to the mothers on nursing, cooking, and how to 
 make clothes for infants. The health visitors should visit newly 
 born infants ten days after birth, at which time the midwife 
 usually ceases to visit. Mothers should bring their infants to the 
 Centre regularly, say once a fortnight. The child or children 
 should be visited by the health visitors until they are one year 
 old, and in cases where progress is not satisfactory, the mother 
 inclined to be negligent, or fails to bring her infant regularly to the 
 Centre, the visits must be frequent. The visits need to be kept 
 up, perhaps at longer intervals, after the first year of life and the 
 mother encouraged to bring the child to the Centre for inspection 
 if its health is unsatisfactory. As a rule, visits may cease at the 
 age of five, or earlier if the child has been entered on a school 
 register, and the records so accumulated as to its condition at 
 various ages should then be passed on for the use of the school 
 medical inspector. Every endeavour should be made to en- 
 courage breast-feeding ; in many towns municipal milk depots have 
 been established in which pure pasteurized milk or dried milk is 
 provided for those infants who are not breast-fed. On these 
 lines, child welfare schemes are doing much good work and are 
 full of promise to prevent many of the disabling illnesses of early 
 childhood, and the child given a good prospect of entering upon 
 its school life in good health. This newer policy is no question 
 of helping the survival of the unfit ; it must be regarded rather as 
 aiming at the survival of children under conditions of healthy 
 normal development and who, in due time, should be best fitted 
 to become capable, healthy future citizens. 
 
 Attention shou'd be directed to the Children Act, 1908. Its 
 first part relates to the control of baby farmers, who must notify 
 
CHILD WELFARE AND SCHOOL HYGIENE 303 
 
 the Eoard of Guardians of any child received by them, and 
 provides for their periodical inspection by an officer of the 
 Board. Under this Act it is a punishable offence to overlay, 
 whilst under the influence of drink, an infant under three years 
 of age. Further, if any person over the age of sixteen, who has 
 the charge of any child and wilfully assaults, ill-treats, neglects, 
 abandons, or exposes the child in such a manner as to cause un- 
 necessary suffering or injury to its health, he or she is liable to 
 a fine of ^100 or imprisonment for two years with hard labour. 
 It is also an offence to leave a child under seven years of age in 
 a room where there is an open fire, unless there be an adequate 
 fireguard to prevent the child being burnt. The penalty is ^"io 
 if the child be killed or suffers serious injury. The Act also 
 enables Local Education Authorities to cleanse verminous 
 school children, and provides a penalty to be inflicted on the 
 parents if the child, after being cleansed, is allowed to become 
 verminous again. 
 
 The general principles governing the arrangements of school 
 buildings have been considered elsewhere in a previous chapter, 
 there remains, however, some points connected with the school 
 child which have a sanitary importance. It is a recognized principle 
 in school hygiene that there is nothing more disabling from the 
 standpoint both of the teacher and the taught than foul air, and 
 the objects kept in view in all structural arrangements of the 
 school building have been shown to be directed to improve and 
 maintain the atmospheric conditions in the classroom, as con- 
 ducive to improve the quality and amount of work performed. 
 In this manner the effects and value of environment of school 
 life are twofold, that is, physical and educational. The latter 
 may be purely educational, in that the scholar is affected by 
 sanitary precept and practice, or it may itself have physical 
 results by favouring or otherwise the mental response and con- 
 sequent general educational results. 
 
 Under the Elementary Education Acts, 1876 and 1899, 
 children from 5 to 14 years of age must attend school ; and under 
 the Elementary Education (Defective and Epileptic Children) 
 and the (Blind and Deaf Children) Acts, 1899 an< ^ I %93> parents 
 must cause abnormal children to receive education up to 16 years 
 of age. In all classes of children attending schools, the ever- 
 present danger is brain-fatigue and over-pressure. This danger 
 is most acute in schools attended by the children of the poor, 
 and the scholars especially liable to suffer from over-pressure are 
 the delicate nervous children, the constitutionally weak, the 
 anaemic and badly fed, also the rapidly growing, excitable, and 
 mentally precocious children. To these must be added, those 
 
304 CHILD WELFARE AND SCHOOL HYGIENE. 
 
 exposed to bad air or bad conditions of study, bad teaching and 
 unhealthy home conditions, those getting too little sleep and 
 recreation, those suffering from defects of sight or hearing, 
 and those at the period of puberty. The prevention of brain 
 fatigue turns largely on there being a school time table which 
 economizes brain energy and directs it on right lines. This 
 means short lessons not exceeding half an hour, a proper 
 sequence and variation of subjects, proper regard to stage of 
 development of the scholar, sufficient intervals for rest, recreation, 
 exercise, and food, fresh air, quiet classrooms, coupled with a 
 strict limitation of the subjects selected for, and the duration of, 
 the home lessons. Home work should never take more than an 
 hour to prepare, and ought never to be given to children below 
 ten years of age. Up to five years of age, a child should be 
 educated through the senses and their activities, then the 
 memory should be developed and good habits cultivated. After 
 ten years of age the child's reasoning powers and imagination 
 develop. Psychologically, the young child is very imitative, 
 craves for approval, is naturally curious and full of activities ; 
 these latter need to be controlled and directed to useful educa- 
 tional ends. On admission to school, every child should be 
 examined as to both vision and hearing. Early attention to 
 these two senses will either lead to a cure or will prevent matters 
 going from bad to worse. For children over eight years of age, 
 the school curriculum should include a course of organized games 
 to draw out and develop physical, mental, and moral qualities. 
 In addition, certain drill exercises are needed which in older 
 children^ say over 14, may well be replaced by gymnastics. 
 Better results are obtained from daily short physical exercises 
 than from longer exercises of greater intervals. 
 
 Little attention appears to be paid to the clothing of school- 
 children. It should be both light and loose, so as not to interfere 
 with any natural function or movement; it must be distributed 
 suitably, so as to regulate the body temperature and guard against 
 chills. The most common and yet easily corrected errors in the 
 clothing of school-children relate to articles which by their pressure 
 and constriction either interfere with the circulation of the blood 
 or lead to deformities ; for example, tight neck-bands or collars, 
 garters, stays, belts, braces, and heavy ill-fitting boots. 
 
 In respect of food, it may be accepted that in terms of water- 
 free constituents the daily diet of a child of seven years should 
 not contain less than 2 ozs. of protein, 2*3 ozs. of fats, and 8 ozs. 
 of carbohydrates ; at ten years of age, the daily need is protein 
 2*5 ozs., fats 3 ozs., and carbohydrates 107 ozs. ; at fourteen years 
 of age, the daily need is protein 3 ozs., fats 3*5 ozs., and carbo- 
 
CHILD WELFARE AND SCHOOL HYGIENE. 305 
 
 hydrates 127 ozs. The Education (Provision of Meals) Act, 
 1906, enables Education Authorities to provide meals for school- 
 children, and to recover the cost from the parent, where possible. 
 Where this is done, supplementary advantage is gained if elder 
 girls can be made to assist in the cooking. In general terms, the 
 diet of school-children should not contain too much meat. Raw 
 apples and nuts and all kinds of fruit are desirable. If sweets or 
 chocolates are given they should be given in reasonable quantity 
 at the end of a meal, and after the appetite has been blunted or 
 more or less satisfied. 
 
 The medical inspection of school-children is imposed upon 
 local Education Authorities by the Education (Administrative 
 Provisions) Act, 1907, at the time of the child's first admission 
 to a public elementary school and at such other times as the 
 Board of Education may direct. The second inspection is usually 
 at the age of 8, and a final inspection made usually at the age 
 of 12 to 13, or one year before the child leaves school. This 
 work of medical inspection is of great sanitary importance, and 
 wherever a sanitary authority employs a female staff, a member 
 of that staff should be present to render assistance to the inspect- 
 ing medical officer. The female sanitary inspector must not be 
 confused with the school nurse, whose duties are to attend to 
 minor ailments of children irrespective of the medical inspection. 
 The mothers are always invited to be present at inspections, so 
 that they may receive instructions from the doctor. The medical 
 officer of health usually supervises the work of inspection which 
 is carried out by assistants. It is regrettable to have to say that 
 of 1,056,315 children inspected not long ago in different parts of 
 England and Wales, no less than 2727 were found to be suffering 
 from phthisis and 3162 others from other forms of tuberculosis. 
 One- sixth of the children of school age are so dull and backward 
 as to be unable to derive reasonable benefit from schooling, half 
 the school-children are in need of dental treatment, and one- 
 twelfth of the children are so defective in eyesight as to be unable 
 to take full advantage of their lessons. Many children of delicate 
 constitution, threatened with or possibly suffering from the early 
 stages of phthisis or other forms of tuberculosis, may with great 
 advantage be taught in schools specially adapted to their needs. 
 Several schools of this kind, in which fresh air, sunlight, good 
 food, and special attention are features, have been established in 
 many parts of the country. 
 
 Elementary public schools are a fruitful source of spreading 
 infectious diseases. The only control towards a mitigation of 
 the evil are the compulsory information supplied under the 
 Infectious Disease Notification Acts and that furnished by 
 
306 CHILD WELFARE AND SCHOOL HYGIENE. 
 
 teachers and others as to whooping-cough, chicken-pox, etc., in 
 the districts where these diseases are not compulsorily notifiable. 
 On receipt of information of a case of infectious disease in a 
 child attending school, the medical officer of health informs the 
 school authorities, so that all children from the same house may 
 be excluded from school until the premises are declared free from 
 infection. If the case be promptly removed to an isolation hos- 
 pital, the clothes and bedding can be disinfected at once, and the 
 other children then allowed to return to school on the expiration 
 of the number of days corresponding to the maximum incubation 
 period of the disease in question. If the child attacked is treated 
 at home, then the other children in the house must be excluded 
 from school until the patient has recovered and all bedding, 
 clothes, and other sources of possible infection disinfected. 
 Small-pox, typhus, scarlet fever, diphtheria, measles, whooping- 
 cough, and cerebro-spinal meningitis are the diseases for which 
 these precautions are most necessary. 
 
 By issuing a certificate, endorsed by the sanitary authority or 
 any two members of it, the medical officer of health has power to 
 close a school, or he may obtain such closure by getting the 
 formal approval thereto of the school medical officer. The closing 
 of schools may seriously interfere with the educational work of a 
 locality, and is a step which should only be taken after most 
 careful consideration. The character of the evidence that the 
 school is the centre of infection must be well weighed, and the 
 nature of the action to be taken will vary under different con- 
 ditions. It is difficult to lay down definite rules as to when or 
 for how long a school or schools should be closed. The nature 
 of the disease, its character, the number of pupils affected, will 
 all be factors in deciding the point, as well as the nature of proof 
 that the sources of infection are really at the school. Much 
 depends upon the amount and promptness of the information 
 which the medical officer of health is able to gain in regard to 
 the circumstances of the school-children and their homes, and 
 the promptness with which action can be taken. Closure of 
 schools is less likely to be efficacious in checking diseases such 
 as measles in a densely populated area than in a sparsely popu- 
 lated one, because the opportunities for intercommunication are 
 so much greater in the one than in the other. What applies to 
 public elementary schools also applies to Sunday schools and 
 private schools. When it does become expedient to close schools, 
 it is desirable that the time specified be a minimum. In certain 
 circumstances the closure of a class is preferable to the closure 
 of a whole school. In the case of measles, for instance, it often 
 happens that practically all the children in the upper classes of 
 
INFECTION AND DISINFECTION. 307 
 
 an infant department have had the disease, and these classes need 
 not be closed. Again, if a single case of measles occurs in a 
 class, it is advisable to close that class, from the ninth day after 
 the sickening of the first child, for five days. During the closure, 
 those who have contracted the disease from that case will develop 
 it, and they, together with children in the same household, alone 
 need to be excluded. The best results are to be expected from 
 a prompt exclusion of all suspects and carrier cases of infection, 
 and as school-teachers become better informed and more skilled 
 in detecting suspicious cases, and as a frequent medical inspection 
 of children in epidemic times is more generally provided, the 
 occasions to close a school will become few and far between. 
 Whatever action be taken in this matter, there must ever be full 
 co-operation between the medical officer of health, the school 
 medical officer, and the head teacher of the school, and that 
 preventive measures should include such internotification between 
 those three and the school attendance officer as will secure 
 this end. 
 
 CHAPTER VIII. 
 
 INFECTION AND DISINFECTION. 
 
 Every one is now familiar with the fact that certain common 
 diseases are due to the entrance within the body from without of 
 certain definite poisons or ferments ; which, having once entered 
 the body, appear there to be able to both grow and multiply. 
 Owing to the poison, after growing and increasing within the 
 body, being capable of being given off again from the body, these 
 diseases are communicable from one person to another, and, as 
 such, are said to be infectious ; while the actual poison or disease- 
 matter itself is spoken of as the infective agent or infection. As 
 the result of improved methods of observation and study, it has, 
 in the case of several of these infectious diseases, been possible to 
 recognize and determine that the actual disease- producing matters 
 or infective agents are minute forms of life, consisting apparently 
 of a single cell, and that all infectious diseases are probably 
 nothing more nor less than the result of the spreading and 
 development within the human body of these small living cells. 
 Existing as they do upon the very borderland of the vegetable 
 
30S INFECTION AND DISINFECTION. 
 
 and animal kingdoms, these minute organisms have given rise to 
 much controversy, not only as to whether they really belonged to 
 the vegetable or animal world, but also as to what they should be 
 called. It is now very generally recognized that they are minute 
 vegetable cells, though their true position among the plants is 
 still unsettled ; and are indifferently spoken of as " microbes," 
 " micro-organisms," " microzymes," " bacteria," " germs," or " con- 
 tagia." No matter how called, all microbes consist of an external 
 covering of cellulose, and an internal living substance called 
 protoplasm, which is quite destitute of chlorophyll or vegetable 
 colouring matter. It is owing to the absence of this green colour- 
 ing matter that microbes, though vegetable cells, differ from the 
 higher plants in being unable to decompose atmospheric carbon 
 dioxide, in which feature they closely resemble the fungi. On the 
 other hand, they differ from animal cells in having a cellulose 
 covering, and by being able to derive their nitrogen from nitro- 
 genous compounds, such as ammonia and nitric acid. 
 
 Microbes vary considerably in form, being either round, oval, 
 rod-shaped, spiral, or filamentous. The round or oval-shaped 
 ones are termed ?nicrococci ; the rod-shaped, bacteria, bacilli, and 
 vibriones ; the spiral forms, spirilla ; while the filamentous forms 
 are generally termed leptothrix when straight, and spirochceta when 
 wavy. Some microbes are provided with flagella or lashing tails, 
 by which they move, while others are devoid of these appendages. 
 The size of these micro-organisms is, of course, very small ; their 
 dimensions, as a rule, varying from about 0*0005 millimetre to 
 0*05 millimetre in length or breadth ; that is, in English measures, 
 something like from ^- -Jyj to ^5-5 inch. 
 
 Microbes multiply or propagate usually by fission or division, 
 while a few increase their kind by means of spores or eggs. 
 These spores are very resistant to all outside influences, and are 
 able to withstand treatment such as boiling for a few minutes, 
 a procedure which readily kills the parent forms. Warmth and 
 heat favour the growth and multiplication of all kinds of micro- 
 organisms ; thus, within an hour, under suitable warmth, a single 
 bacterium divides into two parts, then again in another hour 
 into four, after three hours into eight, and so on until, after 
 twenty-four hours, it has been calculated that the number 
 resulting from a single original one will exceed sixteen millions. 
 It is only by the consideration of facts like the foregoing that 
 the theory and true conception of the nature of infectious 
 diseases can be understood. These diseases are caused and 
 spread by a process resembling the sowing of seed upon a 
 suitable soil, in which, by reproduction of the seed, it, in its 
 turn, becomes a new centre or focus of material whence it may 
 
MTCROBES. 309 
 
 spread and extend to others. A good example of this sequence 
 of events is seen if we sow a little yeast into a solution of sugar. 
 Yeast, we have already learnt, consists of nothing more than in- 
 numerable microscopic plant-cells ; these, on being placed in the 
 sugar, set up fermentation, by which the sugar is split up into car- 
 bon dioxide which goes off into the air, and alcohol which remains, 
 while at the same time an enormous increase has taken place 
 in the number of yeast-cells. If we substitute for the sugar 
 solution the human body, and for the yeast-cell the microbe of 
 an infectious disease, such as diphtheria, enteric fever, cholera, 
 or small-pox, we can readily appreciate the analogy between the 
 process of fermentation and infectious-disease production, and, 
 too, understand that as fresh yeast-cells (only too ready to com- 
 mence their fermenting action) are produced in the sugar solution, 
 so are new disease micro-organisms formed in the body, ever 
 ready, in their turn, to reproduce, on gaining access into another, 
 all the features and peculiar characteristics of their own disease. 
 The close likeness between fermentation and infectious disease 
 processes has led to the term zymotic diseases (from £iV*7j a leaven) 
 being applied to them. The chief infectious diseases affecting 
 man are cholera, chicken-pox, diarrhoea, diphtheria, erysipelas, 
 influenza, measles, mumps, scarlet fever, small-pox, enteric fever, 
 typhus fever, tuberculosis, and whooping-cough. 
 
 If the above conception as to the nature of infectious diseases 
 be correct — and there is every reason to believe it is so — that 
 infection matter is living matter in the form of a primitive plant- 
 cell capable of growing and increasing within the bodies of men 
 and animals, the course of an infectious disease is truly the life- 
 history, so to speak, of a lower plant, and as such has a period of 
 development, a period of its greatest vigour, and a period of 
 decline or death. The time of development, or as it is usually 
 called, the period of incubatio?!, is a most important feature in 
 all diseases ; so, too, is their duration or length of time during 
 which the sick person is liable to be a source of infection to 
 others. Varying, as they do greatly, an approximate idea of 
 their periods of incubation and infectivity is given in the table on 
 the next page ; but it must not be forgotten that occasionally 
 remarkable exceptions to these averages occur. 
 
 The incubation period is that which elapses between actual 
 infection and the appearance of the first signs or symptoms 
 of the disease. In some diseases, as in small-pox, it is almost 
 always of the same length. It is an important fact to know in 
 connection with all infectious diseases, inasmuch as it enables us to 
 say, when a person has been exposed to infection, that after the 
 lapse of a certain number of days, if not already attacked, that 
 
3io 
 
 INFECTION AND DISINFECTION, 
 
 person is safe, and may mix with other people without risk to 
 them. At present we know very little about the changes which 
 take place in the body during incubation, beyond that the poison 
 is multiplying in some part of the system. The majority of these 
 diseases have a short and limited course, ending either in death 
 or recovery more or less complete. A few, like chicken-pox, 
 mumps, and German measles, are remarkably mild in their 
 symptoms ; but, on the other hand, a few are liable to vary 
 greatly in their intensity. This is particularly so with both scarlet 
 fever and small-pox. A general rule seems to be that severity 
 or mildness holds good for the majority of cases occurring in a 
 given outbreak, but that the severer cases are more common in 
 the earlier part of an outbreak than in the latter. Age, sex, 
 race, and season also have an important influence upon the 
 severity of infectious-disease attacks. Many curious facts relating 
 to the peculiar action of the causes of these diseases upon the 
 human body could be related ; how in some cases only people of 
 a certain age or sex suffer, while in others the attacks and deaths 
 are largely confined to those of certain descent or parentage. 
 These and many other points connected with infectious diseases 
 are still but imperfectly understood. 
 
 Disease. 
 
 Chicken-pox . 
 Cholera . 
 Diphtheria . 
 Diarrhoea 
 Enteric fever 
 Erysipelas 
 Influenza . 
 Measles . 
 German measles 
 Mumps . 
 Scarlet fever . 
 Small-pox 
 Tuberculosis . 
 Typhus fever 
 Whooping-cough 
 
 Period of incubation. 
 
 Duration of infectivity. 
 
 IO to 21 
 
 days 
 
 3 
 
 weeks 
 
 I to 5 
 
 55 
 
 3 
 
 55 
 
 i to 6 
 
 5? 
 
 6 
 
 55 
 
 I to 4 
 
 55 
 
 I t02 ,, 
 
 8 to 14 
 
 5> 
 
 6 
 
 55 
 
 1 to 5 
 
 ;> 
 
 1 
 
 55 
 
 1 to 4 
 
 55 
 
 3 
 
 55 
 
 8 to 16 
 
 55 
 
 4 
 
 55 
 
 10 to 20 
 
 55 
 
 t 
 
 o 
 
 »f 
 
 14 to 22 
 
 55 
 
 ** 
 
 j 
 
 >» 
 
 I to 8 
 
 55 
 
 6 to 
 
 s „ 
 
 12 to 15 
 
 51 
 
 6 
 
 55 
 
 unknown 
 
 During the 
 
 whole disease. 
 
 6 to 14 
 
 days 
 
 4 
 
 weeks. 
 
 4 to 14 
 
 55 
 
 8 
 
 55 
 
 Immunity and Protection. — Perhaps the most striking fact in 
 connection with infective diseases is the variability in suscepti- 
 bility to disease conditions exhibited by different persons. 
 Equally remarkable is the fact that insusceptibility to one of these 
 diseases may be acquired by an attack of the same disease or by 
 inoculation of the specific organism, or its products, standing in 
 causal relation to the disease. In other words, non-suscepti- 
 
IMMUNITY AND PROTECTION. 3 I I 
 
 bility, i.e. immunity to a disease, may be naturally possessed by 
 a human being, or it may be acquired either by passing through an 
 attack of the disease or by artificial means of inoculation. 
 
 Natural immunity is the inherent ability of the body tissues 
 to either destroy the invading bacilli or neutralize their toxins. 
 This natural resistance to the invasion of disease-producing germs 
 or their products may be a racial condition, a family condition, or 
 simply an individual condition. It, further, may be destroyed or 
 certainly weakened by a variety of circumstances, such as changes 
 in food or mode of living, under exposure, confinement in the 
 house, or other modifications in environment, conducive to a 
 lowering of the general vitality of the body. 
 
 Acquired immunity may be (i) that induced by recovery from 
 a previous attack of a disease ; (2) that induced by an attack of an 
 allied disease, as in the immunity conferred by vaccinia against 
 variola ; (3) that induced by the injection of antitoxic substances, 
 as in diphtheria ; (4) that induced by the injection of toxins, as in 
 the protection against enteric fever and plague by means of dead 
 cultures of the specific organisms of those diseases. The first two 
 forms of acquired immunity are often spoken of as active im- 
 munity, while that conferred by toxin and antitoxin is designated 
 passive immunity. This latter form of immunity is usually of 
 short duration. 
 
 Various theories have been offered to explain the phenomena 
 of acquired immunity. Thus, Pasteur's " exhaustion " theory 
 assumed that through the growth of the bacteria in the organism 
 they destroyed some substance essential to their life, and so made 
 subsequent growth of the same species impossible in such an 
 organism. Another theory, known as the " retention " theory, was 
 proposed by Chauveau, and assumed that some product of the vital 
 activity of the bacteria was retained in the organism, which was 
 prejudicial to the subsequent development of the same species. 
 Neither of these theories afford a satisfactory explanation of 
 acquired immunity. In order to explain both natural and acquired 
 immunity, Metchnikoff advanced the theory of phagocytosis, 
 according to which the resistance of an animal to bacteria depends 
 on the activity of certain cells called phagocytes, which take up 
 bacteria into their interior, and so destroy them. The ingestion 
 of the microbes by the phagocytes is explained on the hypothesis 
 that the chemical substances elaborated by the bacteria attract 
 the former ; if they fail to do so, then the bacteria remain free to 
 multiply, and general infection occurs. It is possible that phago- 
 cytosis may be the result rather than the cause of immunity ; the 
 theory certainly fails to satisfactorily explain the process of im- 
 munization against a toxin. In direct opposition to Metchnikoff^ 
 
312 INFECTION AND DISINFECTION. 
 
 theory is that of Buchner, which claims that the pathogenic bac- 
 teria are destroyed within the body by the bactericidal action of 
 the blood-plasma and not by the leucocytes ; in other words, the 
 essential factor is humoral rather than cellular. Buchner has 
 applied the term alexin to this hypothetical bactericidal protein 
 substance of the blood and body fluids. Certain experiments of 
 Pfeiffer, in which he demonstrated that if an animal was rendered 
 immune to cholera, and then received an injection of cholera 
 organisms, the injected organisms underwent rapid deterioration, 
 and were completely destroyed, suggested the view that immunity 
 against bacterial invasion was not due to protective substances 
 normally present in the body, but to something which had 
 developed during the course of immunization. This is the theory 
 of antitoxins, which antitoxins are neutralizing agents formed 
 within the body as the result of the vital activities of the body- 
 cells called into action during immunization. 
 
 The difficulties in the way of explaining immunity by any one 
 of these theories are great. Undoubtedly the main point is that 
 the French school attributes to the leucocytes a more important 
 role than that admitted by the Germans; but, possibly, this 
 divergence of views arises from a too rigid adherence to the 
 conception that immunity is always either bactericidal or anti- 
 toxic. All practical experience in the case of the common 
 infective diseases shows it to be neither bactericidal nor anti- 
 toxic, but that it is brought about by the coalition of both cells 
 and serum. An interesting attempt to reconcile the conflicting 
 theories as to immunity is the hypothesis of its mechanism put 
 forward by Ehrlich : its very general acceptance by present- 
 day workers demands a short summary of its essential features. 
 
 Many experiments with bacteria show that the toxins of 
 different species have an especial affinity for the cells of different 
 organs or parts of the body : further, when the amount of poison 
 entering the body is insufficient to destroy the cells which have 
 a special affinity for it, these cells are only injured to such an 
 extent as to permit of repair. Ehrlich conceives the cells of the 
 body as having a complex structure which may be described as 
 being a central mass or nucleus from which radiate a number of 
 bonds or side-chains, each of which seems to bind the cell to 
 other substances. Assuming that a cell has a special affinity for 
 a particular toxin, the combination of the toxin with the cell 
 disturbs its physiological balance leading to a reproduction or 
 repair of damage. The reproduction tends to be carried to. 
 excess. The excess finds its way into the blood-current, and is 
 there capable of combining with further toxin, and so preserving 
 other cells from injury. The excess of so-called side-chain is 
 
 
IMMUNITY AND PROTECTION. 3 I 3 
 
 really the antitoxin, and its union with the toxin results in the 
 formation of a compound which is physiologically inert. Ehrlich 
 recognizes three types of immunity which differ in their mechanism 
 according to the nature of the substance used in the act of 
 immunization. His work upon haemolysis revealed the fact that 
 the blood-serum of an animal, immunized against a different blood 
 to its own, lost its hemolytic power if heated to 5 6° C. for half an 
 hour, but could be re-activated by a drop of normal blood-serum. 
 This fact shows that the hemolytic power of the immune serum 
 was due to two substances, one present in normal blood but 
 destroyed by a low heat, the other present only in the serum of 
 the immune animal. The latter he called the " immune body," 
 and the former the " complement," because of its complementary 
 action. In his later work Ehrlich speaks of the immune body as 
 an amboceptor, a term indicative of its possessing two combining 
 arms, one uniting it with the complement, the other with the blood- 
 cell, bacterium, or whatever the animal has been immunized 
 against : in other words, this amboceptor is specific for the 
 particular cells employed in the act of immunization — that is, if 
 immunized with red blood corpuscles of another species, one 
 receptor or arm unites with the erythrocytes of that species, and 
 the other arm unites with the complement, and so brings about 
 haemolysis or solution of the corpuscles. The same effect follows 
 when the serum of an animal immunized with enteric bacilli is 
 mixed with such organisms; this destruction or solution of the 
 bacteria constitutes bacteriolysis. Hence we may speak of 
 hemolytic sera or bacteriolytic sera. In both these sera the 
 receptors are spoken of by Ehrlich as being of the third order. 
 In the immunity conferred by toxins, when antitoxins are formed, 
 Ehrlich conceives the receptors to be of the simplest nature, 
 possessing only one bond of attachment to which the toxin unites ; 
 these receptors or uniceptors he regards as of the first order. If 
 we immunize an animal with a substance like milk, there forms 
 in the blood of the immune animal a substance which exerts a 
 coagulating effect when mixed with milk of the same species with 
 which the immunization was induced. The receptors which bring 
 this about differ from those of the first order, in that they possess, 
 in addition to their combining element, an enzyme-like part which 
 brings about the coagulation. This form of receptor constitutes 
 Ehrlich's second order. We have reason to believe that normal 
 blood contains a multiplicity of complements ; but according to 
 Ehrlich's hypothesis of the mechanism of immunity, the prehensile 
 parts of the amboceptor and complement must fit each other like 
 lock and key ; if otherwise, they cannot unite. Fortunately, the 
 human complements conform to those of many animals, hence 
 
314 INFECTION AND DISINFECTION. 
 
 animals of this character lend themselves readily to the purpose 
 of preparing immune sera. 
 
 For securing immunity and to discover means for preventing 
 the action of disease-producing bacteria, much work has been 
 done by means of the serum of immune animals, or by the 
 metabolic products of certain micro-organisms. This has been 
 especially the case in respect of diphtheria, tuberculosis, anthrax, 
 and enteric fever. Horses immunized with diphtheria bacilli 
 yield an active antitoxic serum which is not only curative when 
 injected into persons suffering from the disease, but is also a 
 definite preventive agent when injected into those who have been 
 exposed to infection. Although the protection afforded J)y this 
 serum is of rather short duration (three weeks), it is sufficient to 
 serve as a valuable aid in checking the extension of the disease 
 among crowded institutions. The results obtained so far by 
 using the products of tubercle bacilli in the treatment of tuber- 
 culosis have not been so successful, but, as a diagnostic agent, 
 the tuberculin of Koch is valuable for the discovery of the presence 
 of the disease in the early stage in both animals and man. Used 
 in this manner, it is an important agent for the early discovery of 
 the disease in cattle, and indirectly limiting the chances of the 
 dissemination of the disease through milk and milk products. 
 Somewhat similar results have been obtained in the prophylactic 
 treatment of cattle with weakened cultures of the anthrax bacillus ; 
 while the results obtained among men, inoculated with killed 
 cultures of the enteric bacillus, have established the proof of a 
 definite and reliable means for rendering young soldiers and 
 others immune or refractive to this ubiquitous disease. The 
 application of the same method has been distinctly encouraging 
 as against cholera and plague ; even better results have been 
 obtained in hydrophobia or the disease resulting from the bite 
 of a mad dog or wolf. When a person is so bitten, particularly 
 if on the bare skin, he is almost certainly inoculated with the 
 germs or poison of hydrophobia, and which, unless treated by 
 Pasteur's method, generally causes the death of the person bitten. 
 Fortunately, the germs of rabies or hydrophobia take some weeks, 
 often months, and occasionally a year or more, to incubate within 
 the human system before they produce the disease. Pasteur 
 found that rabbits affected with hydrophobia yielded this pro- 
 tecting substance or fluid, and if this were injected into man 
 before the germs from the bite had had time to propagate, the 
 disease could be warded off and prevented from developing 
 itself. Owing to the peculiarly long period which usually elapses 
 between the infection and the outbreak of hydrophobic symp- 
 toms, ample time is given for the body to be saturated with the 
 
VACCINATION. 315 
 
 protective fluid before the poison of the disease begins to act and 
 multiply. 
 
 Vaccination. — The best method of combating infectious 
 diseases will probably be found in the direction of an extension 
 of a practice analogous to that of vaccination against small-pox. 
 This procedure is practically that of inoculating the human being 
 with the lymph or infection juice of small-pox after it has passed 
 through the body or blood of the calf; the result being the infect- 
 ing of the human body or being with a mild form of disease which, 
 while giving rise to little or no physiological disturbance, renders 
 man more or less insusceptible of true and original small-pox. 
 
 In the case of small-pox, the incubation being so much as 
 twelve days, as compared with eight days of incubation for vacci- 
 nation, it is possible by vaccinating a person within the first three 
 days after exposure to infection to modify and possibly prevent 
 small-pox from developing. Many cases have occurred in which 
 this has been successfully done. Instead of waiting, however, 
 for exposure to small-pox infection to take place before seeking 
 protection by means of vaccination, it is better to be vaccinated 
 beforehand. The law requires every child that is born to be so 
 protected by vaccination before the age of six months — unless 
 
 (a) the parent obtains a magistrate's certificate of exemption, or 
 
 (b) the child dies, or (c) is attacked by small-pox within that 
 period, or id) three or more unsuccessful attempts at vaccination 
 have been made, or a medical certificate of postponement (for 
 not more than two months at a time) is given on the ground of 
 ill-health, or of recent prevalence of infectious disease in the 
 district, or of the condition of the house in which the child 
 resides. The parent is relieved from the obligation to have the 
 child vaccinated, if within four months after it is born he satisfies 
 a magistrate that he conscientiously believes that vaccination 
 would be prejudicial to the health of the child, and within seven 
 days thereafter gives the magistrate's certificate to the vaccinator. 
 Some people object to the law as interfering with the individual 
 rights of the citizen ; it is not in any way intended to do that, but 
 rather to protect the community or mass of the people from what 
 is a very great danger, namely, the occurrence and increased 
 intensity of small-pox among unprotected persons. In vaccina- 
 tion, carefully and cleanly performed, and with pure lymph, we 
 have an undoubted means of protecting the race against a horrible, 
 loathsome, and fatal disease. Public vaccinators are to use only 
 glycerinated calf-lymph, or other lymph supplied by the Ministry 
 of Health, and must keep registers from which the origin of the 
 lymph used in each operation can be identified. The instructions 
 require the greatest care as to cleanliness, and sterilization of 
 
316 INFECTION AND DISINFECTION. 
 
 instruments used, and aseptic precautions at all stages. The 
 apparent failure of so-called vaccination to protect against small- 
 pox is really the failure of imperfect vaccination. The lessons 
 taught by recent outbreaks are too clear to be ignored; they 
 point to the necessity of thorough and careful vaccination in 
 infancy (not less than four good marks or scars are essential for 
 safety), and for revaccination between the ages of 13 and 16, to 
 secure protection against small-pox. It is the sham and imperfect 
 vaccination which gives a sense of false security, discredits the 
 whole procedure, and acts as a source of danger to society. The 
 proper and sane view to take of vaccination is, that it does not 
 always prevent small-pox but modifies its virulency, as indicated 
 by hospital statistics, which show that the mortality in the vacci- 
 nated is from 4 to 9 per cent., and in the unvaccinated 49 to 74 
 per cent. 
 
 As regards methods of treatment, the development of the 
 same principle has shown most encouraging results in the success 
 which has followed the treatment of diphtheria by means of 
 " antitoxin." This antitoxin is present in and is yielded by the 
 serum from the blood of horses which have been repeatedly 
 inoculated with the toxine of diphtheria. In a similar way, the 
 efforts to obtain an antitoxic preventive against tetanus by means 
 of the serum of the blood from horses, asses, and goats, previously 
 inoculated with the toxine of tetanus, have been most successful, 
 as evidenced by the control and prevention of this terrible disease 
 among the wounded in the late war. 
 
 The experiences of daily life show that epidemics or out- 
 breaks of scarlet fever, measles, and other diseases of this kind, 
 vary widely in their severity, sometimes being very fatal ; at other 
 times, though attacking large numbers, yet causing few deaths. 
 The thought naturally arises whether, in these milder outbreaks, 
 the intensity of the contagion or microbe has not been lowered 
 by passing through a number of persons in succession, each of 
 Whom was only slightly susceptible to it. Similarly, in the case of 
 the severer epidemics, whether the contagion has not gained 
 intensity by passing through a succession of individuals, each of 
 whom was exceptionally favourable to its development. These 
 are some of the ideas and problems which at present are troubling 
 those whose aim it is to keep infectious disease in check ; their 
 ultimate development and solution are probably but a question of 
 time ; but pending this, attention needs to be closely directed to 
 the modes by which infection generally is given off from the sick., 
 and to the means best adapted for its destruction. 
 
 Means of Infection. — From what has already been explained, 
 it will be clear that although the causes of certain diseases act 
 
MEANS OF INFECTION. 317 
 
 within the body, they really arise from without, and gain access 
 to the body by different ways or methods. The chief means of 
 infection are by air, food or drink, and clothing, to which may be 
 added, in the case of some of the less common diseases, inocula- 
 tion and absorption by some mucous surface. As regards the 
 reception of infection, it is well established that many diseases are 
 conveyed through the air, and the infection inhaled by the act of 
 breathing. This is the probable means of communication of such 
 diseases as small-pox, chicken-pox, scarlet fever, measles, German 
 measles, whooping-cough, mumps, diphtheria, and often tuber- 
 culosis, also of certain infectious forms of inflammation of the lungs. 
 It is not quite clear how far air receives its infectious qualities 
 from the breath of persons infected with diseased throats, or by 
 exhalations and the desquamated particles from the skin. In 
 any case, infection through the air presupposes the existence of 
 microbes, or their spores, in a more or less dry state, floating 
 about as impalpable dust; conditions which we know are not 
 inconsistent with their vitality. Little is known as to the precise 
 distance to which infection can be carried through and by the 
 air, but it probably is not more than some three to six yards. 
 Many instances of so-called infection by means of the air are 
 probably really cases in which infection has been conveyed from 
 one person to another by personal intercourse, such as kissing, 
 embracing, hand-shaking, and talking or playing together. The 
 human element plays a much greater part in the transference of 
 infection than many people realize. Further, food and drink, 
 especially water and milk, are known to convey the poison of 
 enteric fever, cholera, diphtheria, tuberculosis, and even scarlet 
 fever; the germs being in such cases swallowed. Carelessness, 
 and want of cleanliness of the hands, have been the cause of 
 carrying infective matter to the mouth, notably in the case of those 
 tending upon the sick ; while clothing and bedding are most 
 notorious means for the harbouring, preserving, and conveyance 
 of microbes, germs, contagia, and the like. A few diseases, such 
 as glanders, anthrax, erysipelas, and some of the parasitic skin 
 diseases, are more often than not transmitted by either direct 
 contact, or inoculation. In no case can any hard-and-fast rule 
 be laid down as to the precise mode by which any particular 
 infectious disease is communicated to another ; whether by means 
 of air, food, drink, personal contact, inoculation, or clothing. 
 Many of these affections are transmitted by one or more of these 
 ways. Inoculation and absorption are the rarer means of in- 
 fection ; but are very generally associated with the occurrence of 
 such diseases as hydrophobia, glanders, and anthrax, which are 
 distinctive as being common to both men and animals. 
 
3l8 INFECTION AND DISINFECTION. 
 
 In considering sources and means of infection far too much 
 importance has been attached to air, buildings, rooms, their walls 
 and furniture. The truth is, there cannot be a case of infectious 
 disease without a pre-existing case of the same disease, and this 
 may exist either in man or animals. In the majority of instances 
 man and his personal belongings are the source and agent of 
 infection. Not only may man transfer infection to another when 
 he himself is suffering from an infectious disease, but the human 
 being may act as a carrier of infection when suffering from a 
 disease in a mild unrecognized form, or after apparent recovery, 
 and occasionally even when he is not suffering and has not 
 suffered from such disease. These instances are what are known 
 as "carriers" and the large part such persons have played in 
 the spread of infection has frequently been demonstrated in 
 apparently inexplicable outbreaks of enteric fever, diphtheria, 
 dysentery, cholera, scarlet fever and cerebro-spinal meningitis. 
 Apart from man as a source and means of infection, both animals 
 and insects play frequently a large part. Thus, dogs are a source 
 of hydrophobia, rats of plague, mice possibly of some cases of 
 food-poisoning, flies of enteric fever, diarrhoea, dysentery, and 
 cholera, mosquitoes of malaria and yellow fever, fleas and lice 
 of typhus fever, trench fever, and possibly of scarlet fever, while 
 bugs, ticks, and other insects are a common means of infection 
 to man of various tropical diseases. There is, therefore, no 
 mystery as to how man contracts infection, but rather a mystery 
 and marvel that he does not contract infection more frequently 
 than he does. That he does so escape is due to the natural im- 
 munity which Nature confers upon him by virtue of living a clean 
 and wholesome life under clean and wholesome conditions or 
 surroundings. 
 
 Anthrax, or malignant pustule, is a very fatal disease, often 
 given to man from animals, either by means of hair and wool, or 
 from clothing. It is sometimes called woolsorters' disease, owing 
 to its occasional prevalence among men employed in sorting 
 various foreign wools. The infecting agents are the spores of a 
 bacillus. When the spores are ripe, they may either take on a resting 
 stage, or under favourable circumstances, commence germination, 
 like a seed. The spores may infect a farm for many months; 
 indeed, Delepine has shown that in this way most of the outbreaks 
 of anthrax can be explained, the infection clinging to the land for 
 very long periods. The chief channels of infection are (i) by 
 the alimentary canal ; (2) through the skin ; (3) by the respiratory 
 tract. Although alimentary infection is rare in man, it is the usual 
 mode of infection in animals, due to their grazing on infected 
 pasture land. Infected water, as well as fodder, may convey the 
 
ANTHRAX. 319 
 
 disease. Cutaneous anthrax, when it occurs in man, goes by the 
 name of malignant pustule, and is caused by infective anthrax 
 matter gaining entrance through abrasions or ulcers in the skin. 
 It is most common among those whose occupation leads them to 
 handle hides or other anthrax material. From the local sore or 
 pustule, a general infection may result, and when a fatal issue 
 occurs, it is due to the absorption of toxins. Accidental infection 
 with anthrax has been held to be an accident to employees under 
 the Workman's Compensation Act, 1897. Infection through the 
 lungs is perhaps the commonest form in man, and well known 
 under the term " woolsorters' disease," or pulmonary anthrax. 
 This mode of infection occurs when dried spores are inhaled in 
 processes of skin-cleaning. 
 
 To avoid the dangers attending the sorting of the more 
 commonly infected wools, it is necessary and usual to wash and 
 disinfect them, also to insist upon careful washing of the hands by 
 all workmen before eating, and to change their clothes before 
 going home. The actual sorting-rooms must be well ventilated, 
 and artificial arrangements made for carrying away the dust while 
 the bales are being opened. 
 
 By an Order of 1899 of the Board of Agriculture every owner 
 of an animal infected with anthrax must report the same to the 
 police and to the inspector appointed for the purpose by the local 
 authority. 
 
 Where cattle are infected and die, the carcasses should not 
 be opened and exposed to the air. The chief source of danger 
 is the infection by anthrax blood or discharges (containing 
 spore-bearing bacilli) of the fields, farmyard, byres, etc. In 
 these cases it is necessary for thorough disinfection to be carried 
 out, if infection has occurred. When possible, the entire carcass 
 of an infected animal should be burned ; failing this, it should be 
 buried deeply with lime above and below it, and, if possible, the 
 place of sepulture railed off for a term of years to prevent other 
 animals grazing over the spot. 
 
 Chicken-pox. — This, though usually a very mild disease, is, 
 without doubt, infectious. The eruption appears without any 
 previous sickness, commencing on any part of the body, and is 
 added to irregularly by fresh crops of vesicles for four or five 
 days. As in small-pox, the length of the period of its infectivity 
 depends upon the falling off of the scabs or crusts. Assuming 
 that the incubation period of chicken-pox is a fortnight, a deten- 
 tion under observation or quarantine for eighteen days should be 
 insisted upon in the case of all children after exposure to infection 
 by this disease before they return to school or mix with their 
 fellows. Owing to the difficulties often associated with the correct 
 
320 INFECTION AND DISINFECTION. 
 
 diagnosis between chicken-pox and small-pox, it is very desirable 
 that the former affection should be scheduled as a notifiable 
 infectious disease, to minimize the risks of cases of the severer 
 disease being overlooked as being those of the milder one. 
 
 Cerebro-Spinal Fever. — Recent small epidemic outbreaks of 
 this disease in various parts of Great Britain indicate that this 
 disease, sometimes called spotted fever, is a serious danger. It is 
 an acute affection marked by severe disturbance of the cerebro- 
 spinal nervous system. The patient complains of headache, has 
 persistent vomiting and later on passes into a condition of apathy 
 or stupor, accompanied by attacks of delirium and muscular spasms. 
 During the course of the disease, vesicles, spots or mottling of 
 the skin appears. The mortality is high. The cause of this 
 specific disease is the Diplococcus meningitidis intracellulars 
 which infects the cerebro-spinal fluid through the nose and throat. 
 It is undoubtedly highly infectious, the source of infection being 
 in discharges from the nose and pharynx. In cases of this 
 nature, isolation of the sick from the healthy must be carried out 
 at once, and disinfection of all handkerchiefs and other body 
 clothing carefully practised. 
 
 This disease is undoubtedly spread by carriers and persons 
 suffering from mild and unrecognized infection. The number of 
 carriers is high, and there is probably a large proportion of the 
 population who, though harbouring the infective diplococcus, are 
 highly resistant to its infection. The disease is often preceded 
 by catarrhal and influenzal attacks, and it is probable that the 
 specific diplococcus so often present in the naso-pharynx of 
 apparently healthy people is rendered virulent by association 
 with influenza bacilli and some forms of micro-organisms causing 
 nasal and tonsillar catarrhs. As regards prevention, carriers must 
 be segregated in well-ventilated rooms, and not released until two 
 negative swabbings from the posterior naso-pharynx have been 
 obtained. Spit-cups for the sick must be provided, and the 
 greatest care taken to disinfect or burn all handkerchiefs and 
 linen used by them and carriers. Kissing and close contact 
 between the sick or carriers and healthy persons must be abso- 
 lutely prohibited. 
 
 Cholera. — It is usual to speak of this disease as being endemic 
 in that part of India known as Lower Bengal, because it is con- 
 stantly present in that district, but there is reason to believe that 
 its endemic area is not, strictly speaking, limited only to that part 
 of India, but that it is endemic in several countries of Central 
 Asia. From these endemic areas cholera has at one time or 
 ether extended widely over the earth's surface, reaching on more 
 than one occasion even these islands. The mortality from this 
 
CHOLERA. 321 
 
 disease is enormous : in 1866, which was the last occasion on 
 which cholera was epidemic in England, the mortality was 672 
 per million of people; in 1892, when the disease was epidemic 
 in Russia and Hamburg, the mortality was 45 per cent, of those 
 attacked. Warmth of climate seems to favour the activity of the 
 cholera poison, inasmuch as it usually attains its greatest prevalence 
 during the months of June, July, and August. Although all races 
 seem to be liable to attack, the negro race appear particularly to 
 be so. It is now universally acknowledged that the infective 
 agent of cholera is a micro-organism, called from its characteristic 
 shape the comma bacillus; and that this exists in and is given 
 off by the sick person in enormous numbers in the intestinal 
 discharges which are so typical of this disease. In its mode 
 of spread, cholera closely resembles enteric fever and epidemic 
 diarrhoea. In all these diseases, contact with the sick is com- 
 paratively free from danger, provided due precautions are taken 
 not to contaminate any food, drink, or culinary vessels by hands 
 or cloths which have been exposed to the bowel and stomach 
 discharges from the infected person. Infection is given off from 
 the sick solely by the discharges from the bowel and stomach, and 
 the essential need is to prevent any possible contamination of food 
 or drink by their means or clothing and hands soiled by them. 
 There is no infection by the air ; this disease follows human inter- 
 course, and where the cholera-infected person goes there with him 
 goes the cholera infection. 
 
 Water, milk, and various foods are the main agencies by which 
 cholera infection is spread, and invariably the history is that these 
 articles have been either handled by persons actually infected with 
 cholera or have been in attendance on or close association with 
 the cholera stricken. The preventive measures to be adopted are 
 isolation of the sick, disinfection of all clothing, bedding, and 
 excretal discharges, combined with the investigation and correction 
 of all conditions which are conducive to the spread of infection, 
 more particularly faulty methods of disposing of excreta, of 
 bedding or linen and possible fouling of water or food supplies. 
 A matter of considerable importance in this direction is the 
 due appreciation of the fact that the infectivity of cholera evacua- 
 tions last longer often than the existence of acute symptoms. 
 The want of a proper recognition of this fact probably has been 
 the cause of very considerable diffusion of infection in the past. 
 The only safe precaution is to continue destroying by fire, or 
 adequately disinfecting all bowel discharges for at least ten days 
 after convalescence has commenced. This remark is equally ap- 
 plicable to both diarrhoea and enteric fever as it is to cholera. 
 
 Epidemic Diarrhoea, — This is essentially a disease of towns 
 
 M 
 
322 INFECTION AND DISINFECTION. 
 
 and crowded areas, its incidence being greatest upon young 
 children below two years of age. Outbursts of epidemic diarrhoea 
 occur nearly every year, the most usual season being in the 
 months of July and August. 
 
 A variety of micro-organisms have, from time to time, been 
 alleged to be the causal agents of this disease, but the evidence 
 so far does nor warrant our dogmatising on the point. The 
 most we can say is that the epidemic diarrhoea of this country is 
 apparently, in the great majority of cases, the result of the infection 
 of food by bacteria belonging to the hog-cholera group, and which 
 are present usually in faecal matter. It is probable that this infec- 
 tion of food with intestinal bacilli does not lead generally to serious 
 consequences unless the infection be gross from the first, or the 
 food be kept long enough and under conditions of temperature 
 favouring the multiplication of the micro-organism. The infection 
 of milk at the farm, during transit, or by faulty storage in the 
 home, is perhaps the most common 'cause of epidemic diarrhoea; 
 but other foodstuffs are equally liable to infection, especially where 
 carelessness prevails as to cleanly and wholesome storage. It is 
 notorious that towns which have adopted the water-carriage system 
 of sewerage have, as a rule, much less diarrhoea than those retain- 
 ing other methods of excretal removal. Further, towns with the 
 most perfect scavenging arrangements, particularly the removal 
 of house-refuse, have the least epidemic diarrhoea. These facts 
 have suggested that the disease is due to surface pollution derived 
 from street-dust, particularly dried horse-manure. Ballard's in- 
 quiries clearly indicate the influence of soil to be decided, and 
 that communities living upon loose soils suffer more from this 
 affection than those where the dwelling-houses have as their 
 foundation solid rock, with little or no superincumbent loose 
 material. Summing up the position, we may say that epidemic 
 diarrhoea is a bacterial disease, its occurrence depending wholly or 
 partly upon surrounding temperature, deficiency of rainfall, surface- 
 dust, and consequent pollution of food, chiefly milk. The exact re- 
 lationship which these conditions have to each other is not known. 
 
 As already stated, diarrhoea, particularly in its epidemic form, 
 is very fatal to infants, among whom it produces a mortality of 
 about 25 per 1000 of births. The mortality lessens from infancy 
 to 20 years of age, after which it increases again, being particu- 
 larly fatal in extreme old age. Certain industrial and manu- 
 facturing towns enjoy an unenviable notoriety for their very heavy 
 mortality from epidemic diarrhoea every year. Most other large 
 towns suffer in the same way each summer, but in a less degree. 
 
 The prevention of epidemic diarrhoea resolves itself into the 
 prevention of the pollution of the air and soil in and around houses, 
 
DIPHTHERIA. 323 
 
 the encouragement of habits of domestic cleanliness and the pro- 
 tection of food from all sources of pollution. Factors conducive 
 to a high diarrhoea incidence and mortality are domestic over- 
 crowding, darkness and dirtiness of premises, and the keeping of 
 milk and other foods in underground cellars or cupboards ex- 
 posed to soil emanations or in pantries liable to the entry of drain 
 or sewer air and dust. The present-day child-welfare movement 
 and the activities of health visitors should do much to reduce 
 epidemic diarrhoea among children in crowded and populous 
 districts. It is perhaps needless to say that all excretal discharges 
 from these diarrhoea cases need immediate disinfection. 
 
 Diphtheria. — This is another disease largely diffused by the air, 
 more particularly at short distances; the reason being that the 
 microbes of the affection swarm in the exudations and secretions 
 of the nose, mouth, or throat, and infection readily follows the 
 inhaling, swallowing, inoculation, or absorption of any of them. 
 The vitality of the micro-organisms of this disease is great — so 
 much so, that they can survive long periods of time when attached 
 to, or hidden away in, clothing. There is reason to believe that 
 much of the spreading of this affection is due to the crowding 
 together of susceptible persons, such as children in schools where 
 the inadvertent presence of a single unrecognized case in its earliest 
 stage is sufficient to infect, by means of the breath, many others. 
 One of the most striking facts in connection with outbreaks of 
 this disease is, that they are so frequently preceded by a more 
 or less widespread prevalence of cases of sore throat, varying 
 much in severity. So often have outbreaks of true and typical 
 diphtheria, following minor throat illness, occurred in particularly 
 isolated places and under conditions which exclude the likelihood 
 of their having resulted from any importation of the infection 
 from elsewhere, that an idea has grown that possibly ordinary 
 sore throats may be able to acquire a progressive degree of the 
 property of infectiveness. At present there is no precise know- 
 ledge as to the fact of this actually taking place ; but it is 
 suggestive of the need to correct any faulty sanitary conditions 
 of schools and other buildings which may in any way tend to 
 ill health. In connection with the sudden appearance of diph- 
 theria in isolated localities, the question of conveyance by the 
 air or otherwise arises. The experience of the behaviour of 
 diphtheria in houses and hospitals shows that its infection is 
 readily conveyed through the air of rooms for short distances, 
 and to those in close actual contact with the sick ; but there is 
 little evidence in favour of the view that the diphtheria contagion 
 can travel very far and yet retain its virulency. It is much more 
 probable that the infection is transmitted from person to person 
 
324 INFECTION AND DISINFECTION. 
 
 by adhering to handkerchiefs, pillows, or by intimate contact and 
 the fouling of food and cups. The facts connected with more than 
 one outbreak of diphtheria among children and adults have shown 
 the existence of a concurrent throat disease among domestic 
 animals and birds, more particularly cats, sheep, horses, cows, 
 fowls, turkeys, and pigeons. Certain investigations indicate that 
 cats have an ailment suggestive of diphtheria, and that cows can 
 suffer from an ailment so slight in appearance as to be unnoticed 
 by the dairymen, but capable of imparting infective qualities to 
 the milk which give rise to diphtheria among those consuming it. 
 Hence, another reason for sterilising milk before use. 
 
 For many years it was thought that accumulations of filth 
 and drainage defects were the direct cause of the origin and 
 spread of diphtheria. In the light of more recently acquired 
 knowledge, there is reason to think that this older belief must 
 be modified, and that the true part which insanitary states play, 
 is by way of predisposing to infection by lowering the standard 
 of health rather than by being the actual origin 6f the disease. 
 As in the case of scarlet fever, there is no evidence that diph- 
 theria is spread by the agency of drinking-water. Some have 
 said that the diphtheria germ can find a resting-place, in which 
 it can long survive, in the surface soil, and that a rise in the 
 subsoil-water, by expelling the ground-air, leads also to the ex- 
 pulsion of the micro-organisms, and so originates some of the 
 outbreaks of this disease. Modern knowledge suggests that this 
 is not the reason ; the real cause is the existence of " carriers " of 
 the infection either in the house or among the intimates or 
 associates of the inmates. It is estimated that even in non- 
 epidemic periods about one per cent, of the population may be 
 carrying diphtheria bacilli in their throats and that during outbreaks 
 this number may be much exceeded. Among children in infected 
 school class-rooms as many as 25 per cent, have been found to be 
 harbouring the germ, some in a virulent form and others in a non- 
 virulent. School attendance is therefore a very potent factor in 
 the spread of diphtheria as in the case of measles and scarlet fever. 
 The germ in these cases having the power under certain unknown 
 conditions of lying long latent in the nose and throat of both 
 convalescents and carriers, with the capacity of renewing its 
 virulence under special circumstances. This may account for the 
 obscurity of origin of some outbreaks. The remedy lies in 
 searching for these involuntary carriers of infection and treating 
 them on similar lines as indicated for those who harbour the 
 diplococcus of cerebro-spinal meningitis. 
 
 Diphtheria outbreaks are noticeable for being associated 
 frequently with cases of so-called " croup," and with a series of 
 
DYSENTERY. 325 
 
 antecedent cases of scarlet fever. Some doubt has long existed 
 as to the precise meaning of these associated cases; the true 
 explanation probably is that what is called croup is oftener than 
 not unrecognized diphtheria or, at least, a form of laryngitis. 
 In the other association, it is probable that scarlet fever leads 
 to more or less temporary damage to the mucous membrane of 
 the throat, and in this manner predisposes to the reception of 
 the diphtheria poison, causing a series of diphtheria cases to 
 follow after a series of scarlet-fever cases. Both diseases appear 
 to be more prevalent during the autumn and winter, than during 
 the spring and summer. 
 
 The mortality from diphtheria has been much reduced by the 
 early use of diphtheria antitoxin in infected cases. This antitoxin 
 is really the serum drawn from the horse, which animal, by being 
 subjected to repeated injections of the toxin derived from cultures 
 of the diphtheria bacillus, is brought into a condition in which its 
 blood serum possesses very high antitoxic properties against the 
 diphtheria infection. This same antitoxin possesses valuable pro- 
 tective properties and is used with great advantage in doses of at 
 least 1000 units for the protection of children who are or have 
 been exposed to the risks of infection. 
 
 Dysentery. — The term " dysentery " is often applied wrongly 
 to a form of diarrhoea occasionally prevalent in this country. 
 Attacks of diarrhoea with straining and discharges of blood and 
 mucus from the bowel occur, usually as the result of a chill which 
 sets up a slight enteritis, whereby the organisms present in the 
 bowels are enabled to multiply and gain a foothold in the 
 intestinal walls. These cases are really of the nature of a colitis 
 and not true dysentery. Their sanitary significance is practically 
 that of epidemic diarrhoea and the same precautions must be 
 taken both as to disinfection of the discharges and preventing any 
 possible fouling of water, milk, and food supplies. Though we 
 have no precise evidence that these cases of dysentery- like 
 diarrhoea are infectious, it is wiser to act on the assumption that 
 they are. On the other hand, true dysentery is definitely in- 
 fectious, being caused by a specific micro-organism of which 
 several varieties are known. Bacillary dysentery is mainly a 
 disease of the tropics, but cases are constantly arriving in this 
 country. The sanitary precautions in respect of true dysentery 
 should be the same as those advocated against epidemic diarrhoea, 
 and the same may be said of another type of dysentery caused by 
 a small organism known as the amoeba dysenteries. The essential 
 danger lies in any possible fouling of water, milk or food by the 
 bowel discharges from any of these cases. 
 
 Enteric Fever. — This disease is often called typhoid fever, 
 
326 INFECTION AND DISINFECTION. 
 
 and by some Continental writers spoken of as abdominal typhus. 
 It is frequently prevalent in this country, especially during the 
 autumn months. The mortality from and prevalence of this 
 disease in England and Wales has diminished greatly in recent 
 years and the mortality of the present day from this cause is only 
 one-third of what it was ten years ago. True enteric fever appears 
 to be rare among infants and young children ; it is most prevalent 
 in youth and adolescence, the cases becoming fewer and fewer 
 after the age of thirty. Judging by the average severity of attack, 
 more females die from it than males, the figures being 197 per 
 cent, of deaths for female cases, and 13*8 for male. As with 
 many other infectious diseases, enteric fever appears to confer a 
 protection against a second attack ; its incubation period is long, 
 and its course exceedingly variable. Enteric fever is closely asso- 
 ciated with a micro-organism, and is essentially a communicable 
 disease. It is now well established that the poison or infection 
 of this disease is given off fron\ the body of the sick person in 
 association with the excretal discharges, and it is these which 
 are so infectious. Formerly it was considered that the bowel 
 discharges were the chief, if not the only, vehicle by which the 
 infection passes from the body, but more recent investigations 
 indicate that the urine also may serve as the medium for the 
 diffusion of the infective agent. Air does not appear to carry 
 the enteric-fever poison under ordinary conditions ; though when 
 clothing, bedding, and other objects have been soiled by the 
 enteric discharges, and these have been allowed to dry and 
 pulverize, there is no reason to doubt but what an active dis- 
 semination of the disease infection may result by aerial diffusion 
 of dust particles. The most common means by which the infec- 
 tion of enteric fever finds its way into the body of another is by 
 way of the alimentary canal, as for instance along with water or 
 milk. Innumerable instances are on record in which direct and 
 obvious excremental contamination of wells, springs, rivers, and 
 cisterns has been followed by enteric-fever outbreaks. Milk is 
 another medium which has long been recognized as a means for 
 the spread of enteric fever ; the infection being sometimes traced 
 to the use of polluted water for washing out the cans or diluting 
 the milk, and in not a few cases to the milk being infected more 
 or less directly by a person suffering from the disease. 
 
 Other forms of food are probably responsible for about 4 per 
 cent, of cases ; the chief sources from which infection may arise 
 are oysters, shell-fish generally, and green foods which are eaten 
 in an uncooked state, such as watercress. Notable instances of in- 
 fection through all these channels have occurred within recent years. 
 
 Although it is true that, in the greater number of epidemics of 
 
ENTERIC FEVER. 327 
 
 enteric fever, the cases are due to specifically contaminated water, 
 milk, or food, it is not safe to say that the disease is never con- 
 veyed by direct infection, nor must we overlook other possible 
 modes of the spread of this disease. Not the least important of 
 these is infection of food, utensils, clothing, or bedding by persons 
 who carry and harbour the enteric bacilli for many months after 
 recovery from the disease. The existence of these enteric bacilli 
 carriers is now an established fact, and there can be little doubt 
 but that these persons and others who are suffering from unrecog- 
 nized forms of the disease are a fruitful source of direct infection. 
 Many of the chronic carriers are women ; some of them only 
 intermittently give off discharges from the bowel containing the 
 infective bacilli. The habitat of the enteric bacilli in these latter 
 cases appears to be the gall bladder. The danger associated with 
 the employment of carriers as cooks and dairy workers is obvious, 
 but unfortunately several instances have occurred in which out- 
 breaks of enteric fever have been directly traceable to such 
 persons. The custom of the army might well be introduced into 
 civil communities and that is, the forbidding of the employment 
 of any person as a cook and preparer of food who has had enteric 
 fever. 
 
 In places where dry systems of conservancy are in force a 
 possible danger exists in the dislodgment of dried and imperfectly 
 buried excreta from the soil, and their diffusion, as dust, by winds. 
 To this agency we must add the effects of flies which settle and 
 breed upon surface-buried excreta, and then convey the faecal 
 material and its essential bacteria back to the food of man. 
 If specifically infective, even in the absence of direct experi- 
 mental evidence, few persons will be disposed to deny that such 
 dried excretal matter possesses considerable potentialities for evil. 
 
 From time to time, a good deal of evidence has been forth- 
 coming in favour of the view that the air and gases of sewers or 
 drains which have become specifically contaminated may, if 
 allowed to find their way into dwellings through defective house 
 connections, cause enteric fever among the inhabitants of such 
 dwellings. In the light of recent researches, which indicate that 
 sewage is unable to give off micro-organisms to the air in contact 
 with it, we find it difficult to accept this view as to the occasional 
 origin of enteric fever cases, and are compelled to conclude 
 that some more exact causation has been overlooked in those 
 instances. 
 
 Some authorities have dwelt strongly upon the influence which 
 pollution of the earth by specific matter has in originating enteric 
 fever; and in connection with this have traced a connection 
 between movements of the ground-water and the occurrence of 
 
328 INFECTION AND DISINFECTION. 
 
 enteric sickness and mortality. In places where the soil is porous, 
 the ground-water high, and wells and cesspools both more or less 
 adjacent, doubtless this connection between rise and fall of the 
 subsoil-water with fall and rise of enteric prevalence may hold 
 good. Outside the human body, unless existing in pure culture 
 and free from other micro-organisms, the enteric bacillus does not 
 survive long. It has been known to survive in clothing for three 
 weeks and in blankets even longer. It can survive about three 
 days in refuse and soil and for variable periods in water, the 
 probable limit in most ordinary drinking waters being from seven 
 to eight days. 
 
 From this statement of the nature of the infection, cause, and 
 spread of enteric fever, it will be readily understood that the 
 risks of infection from the enteric sick to others is greatest in 
 small and crowded homes, where careful nursing, scrupulous 
 cleanliness as to attendants' hands, and soiled bedding or clothing 
 cannot be secured. When such can be obtained, as in the large 
 hospitals, the enteric sick can be treated side by side with other 
 cases with apparently little risk to the latter ; the chief precautions 
 needed as preventive measures being disinfection of all clothing 
 and articles which have been soiled by the sick, no matter how 
 slightly, scrupulous cleanliness of the attendants' hands, and the 
 exercise of the greatest care to disinfect all excretal discharges, 
 including the urine, and so dispose of them as not in any way to 
 contaminate sources of water, milk, or food. 
 
 As a preventive measure against enteric fever the value of anti- 
 typhoid inoculation holds a definitely high place. The material 
 used is a suspension or emulsion of the dead bacilli of enteric 
 fever obtained from a pure culture killed by heat. The results of 
 anti-typhoid inoculation in the British army has been extremely 
 good, the number of cases of enteric fever occurring among non- 
 inoculated soldiers serving in India and other places abroad being 
 more than five times as great as amongst the inoculated. Should 
 an inoculated man get infected with the disease, the severity of 
 the attack is much reduced and the probability of recovering 
 some nine times greater than had he not been inoculated. The 
 recent experiences in the Great War have confirmed these views, 
 as it was found that the non-inoculated soldier was between fourteen 
 and fifteen times more liable to get enteric fever than the inocu- 
 lated soldier. The results are known to have been much the same 
 in the French, German, and American armies engaged in the same 
 war. Therefore, in anti-typhoid inoculation we have a very power- 
 ful ally in not only preventing the occurrence of enteric fever 
 amongst those exposed to its infection, but also a means whereby 
 human life is saved and the severity of attacks much lessened. 
 
ENCEPHALITIS AND POLIOMYELITIS. 329 
 
 A disease known as paratyphoid fever is sometimes confused 
 with enteric fever. It is closely allied to enteric fever but caused 
 by a quite distinct micro-organism, of which two types are known. 
 Paratyphoid is a much less severe and less fatal disease than 
 enteric fever, but relapses are more frequent. The disease is con- 
 tracted and conveyed by the same means as those mentioned for 
 enteric fever, carriers are as frequently met with, and the value of 
 preventive inoculation equally good. In a word, what has been 
 said of enteric fever applies equally to paratyphoid fever. 
 
 Encephalitis and Poliomyelitis. — Although two distinct 
 diseases, we refer to them together as there is much in common 
 between them from the sanitary point of view. These diseases 
 are specific infections and only received serious attention during 
 the last five or six years. In both cases the cause is a minute 
 micro-organism which is filtrable through porcelain. There were 
 366 deaths from encephalitis in England and Wales during 191 8. 
 Some of these deaths were due to an obscure malady for which 
 the term encephalitis lethargiea was adopted in official reports, 
 others may have been due to the other grouped disease 
 poliomyelitis. Our knowledge regarding encephalitis is at 
 present scanty. It prevails chiefly between June and September 
 and has a high case mortality. The infection is contracted by the 
 nose and pharynx from which cavities it extends to the base in 
 the brain and its coverings, giving rise to severe symptoms such 
 as vomiting, headache, delirium and coma or severe stupor. The 
 discharges from the nose and pharynx appear to contain the in- 
 fection and need to be dealt with on similar lines to those laid 
 down for cerebo-spinal meningitis. There is reason to think that 
 the tw,o infections are closely related, and also that there is some 
 connection between these cases of encephalitis and the more 
 virulent types of influenza. The whole situation is, however, 
 obscure at present, and beyond directing attention to the existence 
 of the malady and its apparent mode of extension, it is unwise to 
 go. Carriers of the infection, who do not themselves appear to 
 suffer, probably play a large part in the dissemination of the 
 disease. 
 
 Of poliomyelitis we know more. The disease occurs 
 sporadically and in epidemic form, especially in summer and 
 autumn. The majority of the cases occur in children' under six 
 years of age in whom it gives rise to partial or complete paralysis 
 of various groups of muscles. For this reason it is sometimes 
 known as infantile paralysis. The incubation period is uncertain 
 but apparently between one and four days. The infection enters 
 by the nose and pharynx and ultimately attacks the anterior 
 cornua of the grey matter of the spinal cord and there sets up 
 
33° INFECTION AND DISINFECTION. 
 
 degeneration of the large motor cells of the coraua. Infection is 
 transmitted by direct contact and the virus appears to be in the 
 secretions of the nose, throat, and possibly of the intestines. 
 Transmission undoubtedly occurs through healthy carriers and 
 mild cases without the characteristic paralysis or severe illness. 
 The virus appears to withstand high temperatures and drying, 
 hence may be conveyed by dried secretions on handkerchiefs, 
 towels, and pillows. There were 178 deaths attributable to this 
 disease in 19 18, returned definitely as such. Discharges and 
 soiled articles from the infected must be disinfected or burnt. 
 The throats and nasal passages of contacts or suspects should be 
 sprayed twice- daily with a one per cent, solution of peroxide of 
 hydrogen, and children from infected homes should be excluded 
 from school. 
 
 Erysipelas. — This has been defined as spreading inflam- 
 mation of the skin, accompanied by fever. It is met with all 
 over the world, but less frequently in the tropics than in more 
 temperate climates. From facts collected by LongstafT, erysipelas 
 has a mortality in inverse ratio to the rainfall, in this respect 
 resembling scarlet fever ; it affects all races alike, and is especially 
 fatal among the very young. Formerly it was usual to regard 
 erysipelas as occurring either through a wound or without. To 
 a large extent this distinction has been replaced by the belief that 
 every case is caused by the poison entering the system through a 
 wound, though this in some instances may be so insignificant as 
 to be overlooked. 
 
 The actual cause of erysipelas is a streptococcus, possibly 
 the streptococcus pyogenes ; it is certainly an infectious disease, but 
 somewhat variable in its infectivity. It at times runs riot in 
 hospitals, especially in surgical wards, the most important 
 favouring circumstances being defective ventilation, overcrowding, 
 want of cleanliness, and defective drainage arrangements. Some 
 people seem to be more predisposed to erysipelas than others ; 
 among such are the intemperate, the badly fed, and those who 
 have had it before. Our knowledge at present is small as to what 
 are the precise connections between erysipelas and the various 
 forms of blood-poisoning, more particularly that peculiar kind of 
 blood-poisoning associated with lying-in women or those recently 
 confined. Evidence is strong that there is a relationship of some 
 kind between erysipelas and child-bed fever, as shown by the 
 familiar fact that women in labour attended by doctors or mid- 
 wives who are suffering from erysipelas, or even have been in con- 
 tact with erysipelas patients, commonly get blood-poisoning or 
 child-bed fever. Similarly, nurses, midwives, and doctors who 
 attend, or come into close contact with, women suffering from 
 
INFLUENZA. 331 
 
 blood-poisoning, frequently themselves suffer from erysipelas ; 
 also the new-born children of mothers with child-bed fever die in 
 large numbers of erysipelas. To a less degree, erysipelas has 
 some obscure relationship to diphtheria prevalence. 
 
 Influenza. — The recent series of epidemic visitations of this 
 disease in this country have made its chief characteristics familiar 
 to most people. Although the original home of this affection is 
 not known, our knowledge is sufficient to convince us that it is a 
 disease which has periodically prevailed in various parts of the 
 world since very early times ; and also that a particular micro- 
 organism stands in causal relation to it. Influenza is remarkably 
 infectious even in quite the early stage. Our knowledge as to 
 how this disease originates and spreads is small ; but what we do 
 know indicates that its progress is quite independent of season or 
 weather ; that man is the chief vehicle of its diffusion ; and that 
 its epidemic prevalence attains its height amongst crowded com- 
 munities. The curious tendency of influenza to recur at intervals 
 in the same locality is suggestive that the contagion or germ may 
 be able to live or thrive for considerable periods outside the 
 human body ; but whether this is in the soil or in the bodies of 
 domestic animals is unknown. That these latter creatures suffer 
 during influenza epidemics from symptoms extremely like it is 
 generally accepted. If similarly circumstanced, both males and 
 females appear to suffer equally from influenza ; its mortality is 
 greatest in the middle and later periods of life, and especially 
 among those weakened by disease, or at all predisposed to bron- 
 chitis and pneumonia. Experience indicates that the ordinary 
 preventive measures are of little or no avail. 
 
 These facts were particularly emphasized in the great epidemic 
 of 1918-19, when the deaths from influenza in 1918 were 112,329, 
 corresponding to a mortality of 3,129 per million of the popula- 
 tion. No such mortality as this has ever been recorded for an 
 epidemic in this country since registration of deaths commenced, 
 and has its nearest parallel in the case of the great cholera 
 epidemic of 1849 when the mortality was 3033 per million. The 
 spread of this disease is to a considerable extent dependent upon 
 mild, unrecognized cases and carriers. There is much to suggest 
 that during an epidemic, the influenza bacillus becomes widely 
 distributed among the population of urban areas, and as many of 
 those infected or invaded are tolerant and resistant or develop 
 only slight symptoms and go about their usual duties, the wide 
 dissemination of the infection is rapidly brought about. Possibly 
 25 per cent, of the population during epidemics may be carrying 
 influenza bacilli in their mouths, noses and pharynges. One thing 
 is certain, and that is the rapidity of spread of influenza is not 
 
332 INFECTION AND DISINFECTION. 
 
 greater than that of human intercourse with modern facilities of 
 travel. The infecting micro-organism is probably the ' bacillus 
 influenza as described by Pfeiffer, as it is found in almost pure 
 culture in the bronchial secretions of influenza cases, but not in 
 other allied diseases. The specially fatal broncho-pneumonia 
 which was such a characteristic complication of the late great 
 epidemic was possibly due to a mixed infection in which certain 
 septic and pus producing streptococci gained access to the lungs 
 after primary infection by Pfeiffer's bacillus. There remains 
 much work to be done in respect of influenzal outbreaks, more 
 particularly to determine their relation, if any, to some other 
 obscure infections which have been noted as often preceding typical 
 epidemics of influenza. We refer to such obscure diseases as 
 encephalitis lethargica, poliomyelitis, and cerebrospinal meningitis. 
 At present we know nothing as to the causes of the establishment 
 of what is sometimes called an epidemic constitution, or that 
 peculiar condition of health or susceptibility to some specific in- 
 fection which seems to be the characteristic of many epidemic 
 outbreaks affecting man, and more especially influenza outbreaks. 
 
 In respect of preventive measures we appear to be not very 
 well informed. Theoretically, notification of cases, isolation of 
 the sick, disinfection of the sputum and of soiled linen, as in other 
 infectious diseases, are indicated as the most suitable means of 
 checking or stopping the epidemic. The practicability of these 
 measures is largely discounted by the difficulty in detecting early 
 infections or mild cases and enforcing the isolation and treatment 
 of persons who are reluctant to admit that they are ill. The most 
 pressing need appears to be early diagnosis and prompt isolation 
 of the first case occurring in a house or family, coupled with 
 minute precautions to disinfect the sputum and other discharges. 
 For those not infected, the rule should be to avoid undue exposure 
 to cold or fatigue, to clothe the body warmly, to be temperate in 
 all things, and not to visit crowded places or centres of public 
 resort while the disease is prevalent. 
 
 Malaria. — This term should be reserved for the specific 
 disease caused by the malarial parasite ; and in that sense we use 
 it here. Malaria is caused by a number of microscopical para- 
 sites which live and propagate themselves in the blood. These 
 parasites are not bacteria or bacilli, but micro-organisms of a 
 more complex nature, namely, protozoa, which are carried from 
 infected persons to healthy ones by the agency of certain species 
 of mosquitoes, notably by the genus termed Anopheles. Formerly, 
 malaria was very common in this country, particularly in the fen 
 and marshy districts, but as the land became better drained and 
 less waterlogged, so the essential mosquito species disappeared, 
 
MALARIA. 33 
 
 -> 
 
 and with it the ague. Malaria is characterized by marked inter- 
 mittency, hence it is usual to speak of it as occurring in three 
 leading forms : (i) quartan, depending upon a parasite which 
 takes seventy-two hours to pass through its cycle of development, 
 and marked by fever every third day ; (2) benign or mild tertian, 
 in which the parasite takes forty-eight hours to complete its cycle ; 
 (3) malignant infections, in which the fever is of a severe and 
 continuous type, and in which the parasites assume a special or 
 crescentic form inside the blood corpuscles. 
 
 The parasites which have been found invariably associated 
 with all forms of malaria belong to the genus Hamamoeba of the 
 class Sporozoa amongst the protozoa. They pass through a 
 definite cycle of development, which is completed in a period of 
 time corresponding to the type of fever or disease. In its earliest 
 and simplest form, the malarial parasite is a motile amcebula 
 existing inside a red blood corpuscle. As the amcebula increases 
 in size, the corpuscle becomes paler, and the parasite living at 
 the expense of the haemoglobin of the corpuscle gradually destroys 
 the blood-cell and converts the haemoglobin into specks of pig- 
 ment. After the parasite has gained its mature size and form an 
 increase and concentration of pigment occurs, followed by a 
 splitting up into segments. This segmentation gives rise to what 
 is known as the " rosette " form. In reality, these segments are 
 new amoeboid bodies, or sporocytes, which, by the rupture of the 
 eaten-out corpuscle, become diffused into the blood. Many of 
 these sporocytes pass into the spleen or are destroyed by phago- 
 cytes or other cells of the body, but, in a few hours, many others 
 reappear in the blood, and inaugurate a fresh stage or infection 
 of healthy blood corpuscles. This is brought about by the 
 sporocytes attaching themselves to and penetrating healthy red 
 blood-cells and setting up a precisely similar series of changes. 
 In this way the multiplication of the malarial parasite is carried 
 on in the human host or body, and each paroxysm of ague or 
 malaria is related to the evolution cycle of a generation of these 
 parasites, the commencement of the paroxysm coinciding with 
 the maturation of a parasitic generation. This human or endo- 
 genous or asexual cycle is known as the " cycle of Golgi," and 
 shown in the accompanying scheme (Fig. 58, 1 to 8). In this 
 way, the parasite is propagated indefinitely in the human host. 
 The form and size of the parasite varies according to the type or 
 variety of the disease ; thus, in quartan malaria the invaded blood 
 corpuscles do not become so decolourized or altered in shape as 
 in other forms, neither is the parasite so motile or so delicate in 
 structure as in the tertian varieties of the disease. The rosette 
 form is distinctly daisy-headed in appearance, consisting of from 
 
334 
 
 INFECTION AND DISINFECTION. 
 
 six to fourteen round spores or elements. In the benign or mild 
 tertian type, the parasite is usually actively motile, showing deeply 
 stained spots, the pigment granules being finer than the quartan 
 parasite. The rosette body in this species is composed of from 
 
 Fig- 58. — Scheme showing human and mosquito cycles of the malaria parasite (after Hanson"). 
 Nos. 1 to 8 show the human or asexual cycle ; Nos. 9 to 24 show the mosquito or 
 sexual cycle. No. 1 is a normal red blood-cell ; Nos. 2 to 5 indicate red blood-cells, 
 containing an amoebula ; Nos. 6 to 8 represent sporocytes ; No. 9 is a young gameto- 
 cyte ; Nos. 11, 13, 15, and 17 are male gametes or microgametocytes ; Nos. 10, 12, 14, 
 and 16 are female gametes or macrogametocytes ; No. 18 is a female gamete being im- 
 pregnated by microgametes ; No. 19 is a travelling vermicule ; No. 20 is a young 
 zygote ; Nos. 21 and 22 are zygotomeres ; No. 23 is a blastophore ; and No. 24 is a 
 mature zygote. 
 
 fifteen to twenty-five smooth oval spores. This type of parasite 
 is probably the commonest form found in malaria, and is widely 
 distributed over the world. In the malignant infections, the 
 amoebulae are much smaller than in the benign types, are very 
 active in their movements, and often exist in enormous numbers. 
 
MALARIA. 335 
 
 Segmentation or sporulation occurs only in the spleen or internal 
 organs, hence the sporocytes are not found in the peripheral 
 blood. The most distinctive feature of this type is the formation 
 of " crescents " (gametocytes), and the attacking of a larger pro- 
 portion of red blood-cells. The crescents do not, as a rule, 
 appear in the blood until about a week from the onset of the 
 fever, and are not a true stage in the ordinary life-cycle : they are 
 uninfluenced by pyrexia, and may persist in man's blood for a 
 long time. 
 
 So far, we have merely considered the life-history of the 
 malarial parasite within the human body, and were this organism 
 unable to escape from man and pass into an intermediate host to 
 undergo further developmental changes, there would be no trans- 
 mission of infection to man. We know now that the necessary 
 intermediate host is the mosquito, and it is only by means of the 
 mosquito that the malarial parasite escapes from the human body, 
 undergoes the necessary developmental changes, and re-enters 
 man's blood. The various changes which take place within the 
 body of the mosquito constitute then the extra-corporeal stage 
 of the life-history of the malarial parasite ; further, inasmuch as 
 man cannot contract malaria without being bitten by a mosquito, 
 nor a mosquito infect another mosquito, so the position may be 
 stated briefly as being " no man no malaria, no mosquito no 
 malaria." 
 
 When malarial blood is observed outside the body, certain 
 flagellated forms may be seen. In the malignant infections, they 
 appear to be derived from the crescents (gametocytes), and in 
 the quartan and benign tertian types of fever from the free spores 
 of the parasite. This striking transformation is a stage of great 
 importance, and indicates a vital evolutionary change or first 
 stage in the life-history of the malarial parasite outside the human 
 body. Just as the segmentation body splits eventually into spores 
 for the further propagation of the parasite in the blood of the 
 malarial patient, so this flagellated body represents a provision 
 for the propagation of the parasite in some living host outside 
 the human body. The living host is the mosquito, and the chain 
 of events may be stated thus. The gametocytes, which in some 
 types of malaria assume a crescentic form, while in others they 
 resemble the mature sporocytes, continue to circulate in man's 
 blood for a while, or until they are transferred to the stomach of 
 a particular species of mosquito. When so transferred, they 
 escape from the enclosing red blood-cell, and can then be recog- 
 nized as being of two kinds, the hyaline and the granular (game- 
 tocytes). The hyaline or male gametocyte emits a number of 
 flagellated bodies (microgametes), which seek out and penetrate 
 
336 INFECTION AND DISINFECTION. 
 
 the granular or female gametocytes. The fertilized female game- 
 tocyte, now called a zygote, acquires locomotory powers, and as 
 a travelling vermicule passes into the muscular wall of the middle 
 intestine of the mosquito. It now grows rapidly, divides into a 
 number of zygotomeres, which become blastophores filled with 
 filiform spore-cells (sporozoits, zygotoblasts, or germinal rods). 
 Ultimately, the zygote becomes encysted and packed full of 
 zygotoblasts. When fully developed, say, twelve days after the 
 mosquito sucked the malarial blood, it bursts and discharges the 
 zygotoblasts, which are reproductive elements or spores. These 
 pass into the insect's large veneno-salivary gland, whence they are 
 emitted into the blood of the subject next bitten. These zygoto- 
 blasts are the actual infecting agents of man, and passing in this 
 way from the mosquito into human blood, at once attack the red 
 blood corpuscles, thus commencing the intra-corporeal or human 
 phase already dessribed. The mosquito phase occupies a period 
 
 Fig. 59. — Larvae of anopheles and culex mosquitoes lying on surface of water. 
 
 varying from six to sixteen days, according to temperature 
 (Fig. 58, 9 to 24). 
 
 Up to the present time human malarial parasites have only 
 been found in species of mosquito belonging to the genus 
 Anopheles. The commonest species of mosquito is the Culex of 
 the genus Culiadce. The larvae of the Culex mosquitoes live 
 almost everywhere in warm countries, inhabiting any pot, tub, 
 or cistern. In the fully developed insect, the palpi are short, 
 proboscis thin, thorax large, and the wings unspotted. The 
 larvae prefer to lie in artificial collections of water, and are pro- 
 vided with breathing tubes (Fig. 59, b). The insect when resting 
 on a wall carries its body parallel to the wall (Fig. 60, b). The 
 
MALARIA. 
 
 337 
 
 host of the malarial parasite or Anopheles mosquito differs in 
 various essential features from the Culex varieties. In Anopheles, 
 the palpi are long, proboscis 
 
 thick and long, body slim, A B 
 
 and the wings dappled with 
 dark spots on their anterior 
 margin. When at rest on a 
 wall, the axis of its body is 
 almost at right angles to the 
 wall. Its larvae have no 
 breathing tubes, conse- 
 quently lie horizontally in 
 the water of puddles (Fig. 
 59, a), looking like bits of 
 thorns floating on the sur- 
 face. While the Cidicidce. 
 are pot-breeding mosquitoes, 
 the Anopheles are puddle- 
 breeding. As is well known, 
 it is the female insect which 
 
 is the blood-SUCker. After FlG - 60.— Anopheles and culex mosquitoes at rest. 
 
 filling herself with blood, she 
 
 retires to some dark sheltered spot near water : in a few days' time 
 she deposits her eggs (300 on an average) in a mass or raft on the 
 surface of the water. Within twenty hours or so, the eggs give rise 
 to the tiny swimming larvae ; these grow, shed their skin, and be- 
 come nymphae or pupae. From the nympha the young mosquito 
 emerges. The entire cycle from egg to egg is about fifty days. 
 
 A particularly virulent form of malaria, known as blackwater 
 fever, occurs in various parts of Africa. It is a very fatal type of 
 infection, but, if recovered from, the malaria parasites which were 
 present in the blood prior to the attack, generally disappear 
 during the process of haemoglobinuria which frequently follows and 
 which would seem to be a method of nature to terminate for good 
 a chronic malarial infection. Apart from its association with 
 malarial parasites in the blood, very little is known as to the 
 cause of the occurrence of blackwater fever. It is so called 
 because of the black or deep blood red colour of the urine which 
 is passed towards the end of the attack. 
 
 Recognizing that the malarial parasite gains access to the 
 human subject by means of mosquito bites only, the means of 
 prevention must be directed mainly against the mosquito, or 
 (1) prevention of mosquito breeding, (2) destruction of mosquitoes, 
 (3) avoidance of being bitten by mosquitoes, (4) the use of 
 quinine, (5) isolation of the infected. 
 
338 INFECTION AND DISINFECTION. 
 
 Measles, Whooping-cough, and Mumps. — These diseases have 
 their infective germ contained almost exclusively in the mucus of 
 the nose, mouth, and throat, or in the breath. They are all appa- 
 rently very infectious, even in the earliest stages, the contagion 
 or germ being capable of spreading, not only by the air, but by 
 clothing, such as handkerchiefs, pillows, and bed-linen. What is 
 known as German measles is a malady seemingly different from 
 scarlet fever and measles, but having some of the characters of 
 both. It is regarded as an entirely distinct disease, inasmuch 
 as it occurs in epidemics, is able to protect against itself, but 
 not against either scarlet fever or measles; nor do attacks of 
 either of these diseases protect against it. Like measles and 
 whooping-cough, German measles is contagious even before the 
 rash comes out; fortunately, it has little or no mortality, and 
 its power of infection is less active and less persistent than 
 those of either measles or scarlet fever. Owing to their early 
 infectiveness, all these diseases spread largely by the attendance 
 of children at schools and other places of public gathering, 
 who are merely sickening for them, and have not so far mani- 
 fested the characteristic symptoms. There is no evidence 
 that these diseases are ever disseminated by the agency of 
 water, milk, or even by domestic animals. 
 
 Measles is largely a disease of infancy and early childhood, 
 and is particularly fatal to young children, owing to lung compli- 
 cations. Adults, unprotected by a previous attack, are also 
 susceptible. The mortality from measles is greatest under three 
 years of age. The case mortality is much affected by over-crowding 
 and general insanitary conditions. Over 10,000 deaths from measles 
 occur annually in England and Wales, the greater number being 
 in the great industrial towns of the Midlands and the North. 
 
 Owing to measles being infectious at the earliest stage and 
 often before the cases can be seen and diagnosed, the prevention 
 of its spread to other susceptible members of a household is 
 rendered very difficult. Prompt notification of recognized cases 
 is essential ; but if this is to be of service it must be followed by 
 prompt visitation of the infected household by the sanitary 
 officials, the source of infection traced, the existence of un- 
 notified cases discovered, schools and libraries informed, and 
 suitable isolation of the case or cases insisted upon. As the cases 
 occur for most part among the poorest, this latter procedure is 
 difficult to carry out. If measles could be scheduled as within 
 the scope of "infectious diseases" as used in the Public Health 
 Acts, 1875 an d 189 1 (London), then forcible action might be 
 taken in respect of the wilful exposure of sufferers, to the great 
 advantage of the public health. 
 
MEDITERRANEAN FEVER — PLAGUE. 339 
 
 Whooping cough tends to occur in recurring epidemics every 
 few years, and generally in association with measles. The 
 seasonal curve for both diseases attains its maximum late in 
 March or early in April. Whooping cough is now one of the 
 most fatal of all the infectious complaints of children under five 
 years of age, the total number of deaths occurring annually 
 being similar to those from measles. 
 
 Mumps occur often in epidemic form, spreading rapidly, but 
 giving rise to little if any mortality. Outbreaks are often associ- 
 ated with measles. The preventive measures in measles, 
 whooping cough,* and mumps are similar, and practically resolve 
 themselves into early diagnosis, prompt notification, and prompt 
 isolation. 
 
 Mediterranean Fever. — This is sometimes called Malta fever, 
 as it prevails much on that island. It is an exhausting and debili- 
 tating fever which usually runs a long course, but fortunately 
 having a very low death rate. Its cause is a minute micrococcus 
 which is to be found in the excreta of goats. Goats' milk is the 
 common source of supply in Malta, and as the udders of the goats 
 get fouled by infected excreta or soil, it follows that the milk of 
 those animals gets infected with the micrococcus and so conveys 
 the disease to consumers. The remedy is obviously to refrain 
 from unsterilized milk, and since 1906 goats' milk has been pro- 
 hibited in military and naval barracks in Malta. The result has 
 been to exterminate Mediterranean fever as a cause of sickness 
 and invaliding from the local garrison. 
 
 PlagUe. — This disease appears to be endemic in certain 
 eastern countries, but has visited western countries in epidemic 
 form, notably London in 1664, when it lasted a year, and caused 
 the death of 63,000 persons. It is caused by a specific bacillus 
 and the infection can be contracted by inoculation, by inhalation, 
 and by swallowing. Human beings are not the only carriers of 
 the contagion, as rats, mice, monkeys, guinea pigs, bandicoots, 
 pigs, and many other animals may and do suffer from this disease. 
 Fleas and flies are known to die in large numbers when exposed 
 to the bacillus pestis, and it is possible that they like mosquitoes 
 may act as carriers. The chief source of primary outbreaks 
 among men are rats, particularly the black rat or mus rattus, 
 which often get affected with plague before human beings are 
 affected. It is certain that the infection passes from rat to rat 
 and from rats to men by means of fleas, and as the black rat is 
 essentially a house rat and fond of human associations, it is not 
 difficult to trace the chain of events once the disease prevails 
 among these rodents. The black rat is not very common in this 
 country as he has been driven away by the fiercer and larger 
 
340 INFECTION AND DISINFECTION. 
 
 brown rat or mus deaimanus, and it happens that the particular 
 flea which infests the brown rat is not identical with the flea 
 which infests the black rat, and, moreover, does not appear to be 
 capable of conveying the plague infection. This difference in 
 both rats and fleas on the rats may explain the non-extension of 
 plague in this country on being introduced. Another reason of 
 our modern immunity from this infection may be that our houses 
 are not usually rat-infested, and that our general domestic arrange- 
 ments are unfavourable to any intimate associations of rats 
 with men. 
 
 There are three distinct types of plague : the bubonic, the 
 pneumonic, and the septicaemia The first named is the more 
 common, but the second named is the most contagious, the third 
 type occupying an intermediate position. In the pneumonic 
 type there is grave risk of infection by means of the breath and 
 droplets of saliva or froth from the mouth. The incubation 
 period of plague varies from two to seven days. Preventive 
 measures are early diagnosis, prompt isolation, and early notifi- 
 cation. Disinfection of all discharges must be rigidly enforced 
 and all contacts or suspects segregated and kept under daily 
 observation for ten days. Infected and rat-infested houses 
 should be evacuated and every endeavour made to destroy 
 rats. An emulsion of soap and kerosene oil is effective in 
 cleaning plague-infected rooms, as fleas exposed to its action are 
 quickly killed. Anti-plague inoculation should be vigorously 
 pushed during times of threatened epidemicity of the disease. 
 
 Rabies, or hydrophobia, is caused by inoculation with the 
 saliva from mad animals, more particularly by bites from dogs, 
 wolves, jackals, and even cats. The incubation period in dogs 
 is from three to six weeks, but it may be both shorter or longer. 
 The symptoms in the dog follow generally three stages. The 
 first is characterized by a capricious appetite, sullenness, irrita- 
 bility, and distrustfulness. If it has been bitten by another dog, 
 there is often abnormal itching at the site of the bite. The 
 second stage is marked by some fury and perhaps convulsions. 
 There is irritability and desire to snap and bite at persons and 
 things. As a rule such dogs do not try to bite human beings 
 unless approached. Hallucinations seem more obvious than 
 mania. In the third stage, the animal is emaciated, worn out, 
 and often paralytic. Death occurs usually between fifth and 
 tenth day. In so-called " dumb madness " in dogs, the second 
 stage may be absent or very short. 
 
 In man, the incubation period after being bitten by a rabid 
 animal may be as short as six days or as long as two years. The 
 average period is six weeks. The early symptoms are malaise 
 
RELAPSING FEVER — SCARLET FEVER. 34 1 
 
 with often pain at site of bite, and aversion to fluids. Later, 
 spasms, delirium, or mania may supervene. The spasms affect 
 chiefly the throat. There is much anxiety, thirst, and failure to 
 swallow saliva. The paralysis and spasms increase and death 
 usually occurs in from two to four days. The only effective 
 treatment is that by the Pasteur method, but to be effective in 
 warding off the disease it must be carried out so soon after the 
 original bite as possible. As rabies is spread in this country only 
 by infected dogs, it follows that the only effective preventive 
 measures against this terrifying disease are enforcement of the 
 muzzling regulations and the destruction of all stray dogs. 
 
 Relapsing Fever. — This is sometimes called " famine fever," 
 and is very closely related to typhus fever. Climate and weather 
 have no direct influence on this disease. Its chief causes are 
 overcrowding and uncleanliness. It is very infectious, the germ or 
 cause being conveyed probably from person to person by means of 
 ticks and other blood-sucking insects. The germ is a peculiar wavy 
 micro-organism, called a spirillum, and inoculation of the same has 
 been found to reproduce the disease in men and monkeys. Relaps- 
 ing fever appears to afford but little protection against subse- 
 quent attacks, but does seem to have some protective action 
 against typhus. 
 
 Scarlet Fever. — In this disease the infection reaches the air 
 in the early stages, even before the rash appears, chiefly by the 
 breath and mucous secretions of the nose, mouth, and throat. 
 These secretions remain infectious throughout the whole course 
 of the illness and for some time after convalescence. The 
 popular view that infection attaches to the desquamation or 
 peeling of the skin, which is so characteristic of this disease 
 in the later stages, we think to be based on a misconception. 
 The infectious discharges from the nose, throat, and also from 
 the ears, render clothes, bedding, and other personal belongings 
 of the sick highly infective. On this account, every care should 
 be taken to disinfect or burn all handkerchiefs, bedding, and 
 clothing which has been used by the sick person. There is no 
 evidence of scarlet fever infection being conveyed by water, 
 nor of its being carried any great distance by air-currents. 
 On the other hand, there is much to suggest that it can be 
 conveyed by milk. 
 
 The usual duration of infectiveness in scarlet fever is six 
 weeks, but it may be prolonged much longer, especially if there 
 be any discharge from nose or ears. Like many other in- 
 fectious diseases, scarlet fever is disseminated by mild and 
 unrecognized cases, possibly also by carriers who have been 
 in contact with cases and harbour the specific germs, though 
 
342 INFECTION AND DISINFECTION. 
 
 unaffected by them. The disease is essentially a disease of child- 
 hood, the incidence being greatest at from five to six years of 
 age. Its virulence has lessened greatly in recent years, but 
 the disease is still the cause of much sickness amongst children, 
 and schools play a great part in disseminating the infection. 
 Overcrowding and insanitary conditions in houses help to ag- 
 gravate the severity of attack and to aid in their dissemination. 
 The preventive measures to be adopted are those applicable 
 to other diseases of the kind, namely, early detection and 
 notification with prompt isolation of the risk and segregation of 
 contacts and suspects. 
 
 Simple Continued Fever. — A disease under this name is 
 scheduled in the Infectious Diseases Notification Act of 1889 as 
 one to be duly notified to the sanitary officials. It is doubtful 
 whether any separate disease of this name really exists. The 
 term is usually applied to cases of more or less transient fever, 
 unattended by any definite and constant symptoms other than 
 those commonly associated with a high body heat. Careful 
 inquiry generally throws light upon the cause of these cases, a 
 great number of them in reality being but mild and irregular 
 examples of more serious diseases, such as enteric fever, typhus, 
 or even measles ; hence the great practical value of duly giving 
 notice of their existence. 
 
 As other examples of what may be and often are returned or 
 regarded as cases of simple continued fever may be mentioned 
 sandfly fever of the tropics and trench fever. The former is a 
 simple and non-fatal fever of comparatively short duration, which 
 is a frequent source of sickness in eastern countries. It is chiefly 
 interesting as being due to infection by sandflies and can be pre- 
 vented only by safeguarding oneself from bites by those aggressive 
 insects. The infection known as trench fever, for want of a 
 better name, is an infection undoubtedly conveyed from man to 
 man by lice. It was first recognized among soldiers in the late 
 war, but it may occur under civil circumstances with similar 
 conditions as to personal uncleanliness. It is a fever of ar* 
 irregular type, fortunately attended by no mortality. It often 
 runs a long course with relapses, and tends to leave the con- 
 valescent debilitated and inclined to nervousness. Little by 
 little these disabilities pass off and the sufferer becomes restored 
 to his former health. From the sanitary point of view the 
 disease has an importance as being but another instance of how 
 a specific infection can be and is conveyed from man to man 
 by insects and vermin. 
 
 Small-pox is infectious from the very commencement of the 
 disease, the infection gaining intensity as the eruption advances, 
 
SMALL-rox. 343 
 
 even up to and including the scabbing stage. The microbes or 
 germs of the disease are contained in the secretions of the nose, 
 mouth, and air-passages, as well as in the contents of the pustules 
 or pocks. They are given off most freely, when these latter dry 
 and scab, diffusing themselves to great distances in the form of a 
 fine dust. Owing to the great resisting power or vitality of these 
 microbes, the spread of small-pox by means of infected clothing 
 is even greater than that of scarlet fever. Individual protection 
 against an attack of small-pox can be obtained in three ways : by 
 natural small-pox, by inoculated small-pox, and by vaccination. 
 In former years, protection once acquired was looked on as per- 
 manent and absolute ; but later experience shows that from what- 
 ever cause obtained, the amount of protection varies according 
 to the thoroughness of the protective procedure. Severe small- 
 pox gives more lasting protection than mild small-pox ; small-pox 
 inoculation gives most protection when followed by an eruption ; 
 and a complete, thorough, and multiple vaccination gives more 
 lasting protection than does a vaccination in which only a single 
 small vesicle has been produced. 
 
 Protection from small-pox by deliberate inoculation of the 
 disease, or variolation, as it was called, was very generally practised 
 in this country during the eighteenth century, and until made illegal 
 in 1840. The chief objections to it were the danger to life which 
 attended it, the disfigurement which so generally followed, and 
 the fact that the inoculated went about spreading the disease 
 broadcast. The researches and observations of Edward Jenner, 
 between 1768 and 1798, led to the introduction of vaccination, 
 or the inoculation of man with the small-pox of the cow, by which 
 man contracted the affection called vaccinia. This vaccinia is, as 
 Jenner always supposed it, small-pox of the cow; but owing to 
 the remarkable change in the cow or calf of small-pox into 
 vaccinia, the poison of human or ordinary small-pox is so 
 weakened as to be unable to cause, except in rare cases, a general 
 eruption or to spread by atmospheric convection ; in fact, to use 
 the words of McVail, the change in the calf from small-pox to 
 vaccinia has the effect of " removing the objectionable and retain- 
 ing only the valuable part of the original disease." Following 
 the introduction of vaccination, there resulted a remarkable 
 decline in the prevalence of small-pox, not only in England, but 
 in various European countries. 
 
 Vaccination in this country is generally performed within the 
 first three months of life, and under the Vaccination Acts must be 
 performed before the age of six months unless an exemption 
 certificate is given by a medical man that on health grounds it is 
 undesirable, or exemption is obtained as the result of the parent 
 
344 INFECTION AND DISINFECTION. 
 
 making a statutory declaration before the child reaches four 
 months that ,he objects conscientiously to vaccination. The 
 statutory declaration must be made before a justice or a com- 
 missioner of oaths, and must be sent to the vaccination officer 
 within seven days after it has been made. The efficiency of 
 vaccination depends upon the number and character of the 
 resulting scars as indices of the efficiency of the operation. The 
 protective influence wears away with the lapse of time and re- 
 vaccination at or before the age of puberty is a necessary 
 measure if protection is to be maintained during manhood. 
 In times of small-pox epidemicity even a third inoculation with 
 vaccine may be desirable for those in whom a long interval has 
 elapsed since a previous vaccination or re- vaccination. Calf lymph 
 and that from a vaccine of the eighth day from a healthy infant, 
 if used perfectly fresh, are equally efficient as regards protection. 
 
 The present-day apathy as to vaccination results largely from 
 the present generation being unfamiliar with the loathsome 
 nature of the disease, and the disfigurement which results from 
 severe or confluent attacks should recovery ensue. The evidence 
 as to the beneficial effects of vaccination both as a means of 
 lessening susceptibility to infection by small-pox and of reducing 
 the severity of attack should it occur is overwhelming. The 
 following figures given by Kidd as to 3057 cases of small-pox 
 occurring at Gravesend in young persons of 15 years of age is 
 typical of the value of vaccination as an agent in mitigating both 
 severity of attack and mortality. Of these cases, 673 had been 
 vaccinated in infancy, and only 9 died, but 7 of those 9 
 deaths occurred in those over 10 years of age. The remaining 
 2384 cases had never been vaccinated, and of them 668 died, no 
 less than 142 of these deaths being in those over 10 years of age. 
 These facts show that the death-rate in the vaccinated was 1*3 per 
 cent., and the death-rate among the unvaccinated was 28 per cent. 
 Further, the proportion of severe cases among the unvaccinated 
 was 7 3" 2 per cent, as against 24*8 per cent, among the vaccinated. 
 These recent figures are absolutely in accord with experiences in 
 the great epidemics of the past, such as those which occurred in 
 Sheffield^ Dewsbury, Leicester, and Gloucester. An analysis of 
 the evidence available from these outbreaks of small-pox indicates 
 that during small-pox prevalence, an unvaccinated child under 
 10 is 440 times more liable to die than a vaccinated one, and an 
 unvaccinated person over 10 is 55 times more likely to die than a 
 vaccinated one. Also, that unvaccinated children under 10 years 
 are 20 times more liable to attack than the vaccinated, and 
 unvaccinated persons over 10 are 5 times more liable. 
 
 The prevalence of smaii-pox in England and Wales has 
 
SMALL-POX. 345 
 
 diminished almost to vanishing point during the last twenty years, 
 and this notwithstanding the lessened number of children who 
 are vaccinated in infancy and the neglect of re-vaccination. It 
 has been alleged that this is due to so-called sanitation and better 
 administration. These improved methods, however, do not 
 challenge seriously the value of vaccination because they fail to 
 explain : (i) the fact that small-pox mortality has been transferred 
 from childhood to the later periods of life since vaccination has 
 been introduced ; (2) the immunity enjoyed by nurses, postmen, 
 sorters of letters, and others who have been re-vaccinated and yet 
 exposed to constant chances of infection ; (3) that the disease 
 passes by the vaccinated children but attacks the unvaccinated 
 children living in the same dwelling ; (4) the lessened fatality 
 among the vaccinated if attacked; (5) that those with three or 
 four good vaccination marks are less liable to a fatal attack than 
 those with one or two marks ; (6) that the disease has never been 
 shown to be caused, directly or indirectly, by any insanitary 
 condition. A further criticism against vaccination has been the 
 statement that it imparts diseases other than vaccinia. The 
 evidence in support of such statements is weak. Some cases of 
 vaccino-erysipelas have undoubtedly resulted, but only either 
 directly from the failure to take due precautions as to cleanliness 
 at the time of operation, or indirectly from exposure to dirt and 
 insanitary conditions in the home of the recently vaccinated 
 infant or person. Allegations of this kind have been grossly 
 exaggerated and with the routine use of glycerinated or chloro- 
 formed calf-lymph and the adoption of aseptic measures in the 
 actual operation, the risks of conveying any vaccinal disease are 
 remote, and not greater than risks of complications as occurring 
 in the performance of other minor operations. 
 
 The danger of the present position in respect of small-pox is 
 the increasing number of infants who escape vaccination, the 
 increasing number of persons who fail to be re-vaccinated, and 
 the consequent increase in numbers among the general population 
 of those who are unprotected against the disease. Excellent as 
 they are, modern sanitary administration methods and the free 
 isolation' of small-pox cases in hospitals are not sufficient substi- 
 tutes for vaccination in the control of the disease. At best, they 
 are but useful auxiliaries. The weak point is the failure to secure 
 isolation in all cases with the necessary promptness and thorough- 
 ness. This results from difficulties in diagnosis, late diagnosis 
 and late notification, delays in removal or isolation, occasional 
 inadequacy of hospital accommodation during epidemics, and the 
 frequent inefficiency as to disinfection of all infected articles. 
 
 Recent criticism suggests that vaccination is really a source 
 
346 INFECTION AND DISINFECTfON. 
 
 of weakness to the administrative control of small-pox, because 
 the presence in a population of large numbers of persons more or 
 less protected only by a previous vaccination leads to the 
 occurrence of numerous cases of mild or modified small-pox 
 which are difficult to diagnose, with result that the public health 
 is endangered by true cases of small-pox being missed. To this 
 it may be remarked that there is no guarantee or certainty that 
 errors in diagnosis would be reduced if the population was 
 entirely unprotected by vaccination ; further, it is not only the 
 cases of small-pox modified by previous vaccination that cause 
 errors in diagnosis, but also the mild cases of the unmodified 
 disease. The suggestion has the further objection that it ignores 
 the fact that infantile vaccination is primarily a protection to the 
 child population against the most loathsome of diseases, and that 
 the effects of the discontinuance of infantile vaccination would 
 fall most heavily and with distressing results on the most helpless 
 section of the community. No one who has seen cases of small- 
 pox in vaccinated and un vaccinated children can disregard the in- 
 dividual aspect of this question and consider only the possible and 
 doubtfully beneficial effects on the community as a whole. It 
 does not seem to be in the interests of the community that those 
 parents who are desirous of protecting their children should be 
 discouraged from doing so in order that others may reap a 
 problematical advantage. Even if a vaccinated person or child 
 do pass on a modified attack of small-pox in a virulent form to 
 an unvaccinated person or child, are we to lay the blame for 
 that person's or child's misfortune on the practice of vaccination, 
 or upon those who, directly or indirectly, were responsible for the 
 person's or child's unvaccinated condition ? Moreover, on 
 general grounds, there appears to be reason to think that small- 
 pox is less likely to become epidemic in a partially protected 
 community than in an entirely unprotected one. 
 
 As regards prevention and control of small-pox, early diagnosis 
 and prompt isolation are the first elements of attack and defence. 
 The diagnosis from chicken-pox is not always easy, and in times 
 of small-pox prevalence chicken-pox should be made a notifiable 
 disease. It is the first case of small-pox mistaken for chicken- 
 pox or for a non-variolous eruption that gives rise to the trouble. 
 Once small-pox is diagnosed, the case should be removed at 
 once to an isolation hospital and the polluted room aired and 
 cleaned, and all incriminated clothing and bedding disinfected. 
 All other inmates of the house and all contacts should be at once 
 vaccinated. Contacts and all who have been in personal com- 
 munication with the sick person must be either put in quarantine 
 for fourteen days or visited daily for inspection and prompt 
 
TETANUS — TUBERCULOSIS. 347 
 
 isolation on the appearance of initial symptoms. Schools attended 
 by children in the house should be notified of the case. In 
 respect of vaccination of contacts and others, it is probable 
 that if vaccination be performed on a person who has already 
 contracted small-pox, within forty-eight hours of the exposure to 
 contagion, vaccinia ensues and small-pox is avoided. But if 
 vaccination is delayed to a later hour, small-pox is usually 
 contracted, but in a modified form if vaccination be performed 
 within three days, unmodified if later than this, with vaccinia 
 possibly running its own course at the same time. 
 
 Tetanus, or lockjaw, is essentially a soil or earth-poison 
 disease, due to the presence of a bacillus. It is not infectious, 
 but commonly occurs as the result of the inoculation or fouling 
 of wounds by dirt, mud, or earth : this is the reason why it so 
 frequently follows injuries to the hands and feet. Its prevention 
 rests on the immediate removal by careful washing of all earth, 
 mud, or soil from cuts or wounds, should such contamination 
 have occurred. To these measures should be added the injection 
 of anti-tetanic serum by a medical man as soon as possible. The 
 value of this procedure was particularly proved in the Great War, 
 as shown by the small number of wounded who developed tetanus, 
 notwithstanding gross fouling of their wounds by mud, dirt, and 
 soil-tainted fragments of clothing. 
 
 Tuberculosis. — This is a diseased condition which occurs in 
 man in a variety of different forms, the most familiar being 
 phthisis or consumption, scrofula, and meningitis. Tuberculosis 
 is not limited to the human race; it is very common among 
 oxen and cows as a disease known as " grapes," it also affects 
 pigs as well as fowls, rabbits, and guinea-pigs. It is causally 
 related to the action of a particular bacillus, and the existence of 
 these bacilli in the expectoration of those afflicted with consumption 
 or tuberculosis of the lungs, and in the milk of cows suggests the 
 communicability of this disease either by the air or by food, 
 especially milk. The identity of the human and bovine forms of 
 the disease is now recognized, consequently we have no difficulty 
 in understanding that all forms of tuberculosis in man and animals 
 are produced by the same organism ; the more usual modes of 
 infection in man being by way of ingestion and inhalation. Speak- 
 ing generally, ingestion tuberculosis is a disease of child life, 
 inhalation tuberculosis is a disease of young adult life, although it 
 may occur at all ages. There are a certain number of cases of 
 tubercular infection which present difficulties to explain the pre- 
 cise path of infection ; but, whatever the path, it is certain that 
 the bacillus must pass through some portion of either the alimentary 
 or of the respiratory tract. 
 
348 INFECTION AND DISINFECTION. 
 
 Whatever is the path of infection, we must ever regard tuber- 
 culosis as an infection, that is, due to a virus which is introduced 
 into the body from without. The bacillus is essentially a parasite 
 and not a saprophyte, having no independent existence outside 
 the body ; but there are numerous sources of infection by tuber- 
 culous material from both human beings and animals the subjects 
 of the disease. Thus, from mankind there is the sputum from lungs 
 in pulmonary tuberculosis ; the faeces or urine when the intestines 
 or urinary tract are the seat of the disease ; also the discharges 
 from tuberculous ulcers or fistulae. Milk from a tuberculous cow 
 is an undoubted source of infection, also the meat or flesh from 
 oxen, pigs, or fowls affected with tuberculosis. Probably the most 
 important of all these, however, are cows milk and human sputum. 
 
 As regards direct contagion^ it must be confessed that clinical 
 observation is somewhat opposed to the idea that direct infection 
 from another patient is at all common in the etiology of tubercular 
 diseases. Experiments have indicated that infection with dry 
 powdered sputum is undoubtedly possible, but seldom happens, 
 because the very finest dust particles suitable for aerial convection 
 are only derived from perfectly dried sputum, and then in small 
 quantities only. Greater danger lies in the dissemination of 
 infection by means of the fine droplets of saliva given off in the 
 act of coughing or talking. Such droplets have been shown to 
 be abundant within 50 centimetres, or say two feet from the 
 mouth, whilst beyond 1^ metres, or say five feet, they are rare. 
 For these reasons continuous association with frequent close 
 approximation as in the case of married couples, nurses, crowded 
 workshops, etc., will greatly increase the likelihood of infection, 
 whereas mere occasional visits and conversation at a distance of 
 not less than a yard reduce the probability almost to nil. We 
 ourselves are disposed to think that bovines are the main source 
 of tuberculosis in man, and that infection by inhalation occurs 
 only as the result of prolonged and closest intimacy. The con- 
 clusion, therefore, which we form on this matter is, that the 
 infection of tuberculosis reaches man occasionally by the flesh 
 of bovines eaten in a partially cooked condition, less frequently 
 by direct infection from another human being, but most frequently 
 by cow's milk containing bovine tubercle bacilli derived from cows 
 who are themselves the subject of tuberculosis. It follows from 
 this that the period of greatest liability to infection from this last 
 source is infancy and early childhood. The sequence of events 
 warrants the further view that in civilized communities, such as our 
 own, large numbers of children in early life are invaded by the 
 tubercle bacillus in small doses or in an attenuated form. Many 
 acquire thereby an immunity in greater or less degree to subse- 
 
TUBERCULOSIS. 349 
 
 quent invasion by virulent bacilli in effective doses, and, probably, 
 in as many others the infective micro-organisms remain latent in 
 the mesenteric or other lymph glands until circumstances render 
 the body a suitable medium for the multiplication of the germs 
 and consequent general or local manifestation of the infection. 
 
 The above views are not inconsistent with experience in 
 respect of what appear to be predisposing causes to tuberculosis. 
 These are poverty, bad housing, overcrowding, bad ventilation, 
 foul air, insufficient daylight, insufficient nourishment and clothing, 
 exhausting occupations, alcoholism, and disorderly mode of life. 
 These factors all contribute to diminished resistance, and, given 
 the presence of the infecting micro-organisms either within or 
 with ready access to the human body, infection readily follows. 
 The incidence of tuberculosis falls on all classes and at all ages. 
 Females appear to be slightly less affected than males. It is the 
 most fatal of diseases, and there is no greater drain on the man- 
 hood of a nation than tuberculosis. There were 58,073 deaths 
 from this disease in England and Wales during 1918; of these 
 deaths, 46,077 or 79 per cent, were from phthisis or pulmonary 
 tuberculosis. Generally speaking, there has been a progressive 
 reduction in the death-rate from this disease in recent years, but 
 the existing mortality is still far too high. The reduction is most 
 marked during the 10 to 35 years age period. Children under 
 five years have a higher mortality from tuberculosis than exists at 
 any other five year age period, and this is due to the greater 
 prevalence of other forms of tuberculosis than phthisis. 
 
 Preventive measures promise the best results along the two 
 main paths of educating the people as to the danger and means 
 to avoid it, and improved sanitation and methods of administra- 
 tion. Education means the giving attention to personal hygiene, 
 advantages of cleanliness, fresh air and sunlight, the suppression 
 of spitting, the need of separate bed and room for the infected, 
 and the shielding of the mouth when coughing, with routine use 
 of special spittoons. On the administrative side, the protection 
 and improvement of the milk supply holds the first place. Once 
 the elimination of tuberculous milk from the dietary of the masses 
 can be secured, the chief source of infection will be removed. 
 The notification of phthisis is compulsory under the P. H. 
 (Tuberculosis) Reg. 191 2, and the same regulations give the 
 sanitary or local authority full power to take active measures in 
 respect of advice to the sufferer and dealing with contacts or 
 suspects, and for the removal of domiciliary or other conditions 
 known to promote the incidence of the disease. Further, they 
 are authorized to establish special departments and prepare 
 schemes for dealing with tuberculosis cases. Under the National 
 
350 INFECTION AND DISINFECTION. 
 
 Insurance Act, 191 1, the provision of Tuberculosis Dispensaries, 
 Sanatoria and Hospitals for advanced cases are authorized to be 
 established. The dispensary is really a clearing house for tuber- 
 culosis in the district which it serves. Here the tuberculous are 
 examined or visits paid to the home by the dispensary officers, 
 treatment given, and efforts made to obtain improvements in 
 environment. That part of the insurance benefit known as domi- 
 ciliary treatment, and intended for such patients as are unsuitable 
 for admission to an institution, is also usually carried out from 
 the dispensary. The sanatorium is an important link in the chain 
 of preventive measures and is intended mainly for the treatment 
 of early cases. The hospital for advanced cases is really an 
 isolation hospital for tuberculosis, and, from the preventive point 
 of view, possibly the most important factor. Disinfection of 
 clothing, bedding, and handkerchiefs in cases of tuberculosis is 
 essential. 
 
 There are some weak points in the existing schemes for 
 dealing with the tuberculous. One is that there is no general 
 power to compel patients to submit to isolation. Another is 
 that too often the stay in a sanatorium is too short, and the after 
 care of those discharged from sanatoria left to chance. Gradually 
 these defects will doubtless be remedied, and the prospects of 
 a more comprehensive control over tuberculosis by the local 
 authorities in the future is full of promise, more especially as 
 their powers to control the inspection of cows and the sale of 
 milk are much extended under the Milk and Dairies Acts of 
 1915 and 1920. 
 
 Typhus Fever. — In former years, this disease was much more 
 prevalent than now. It is very rarely met with in the present 
 day, except in the poorest, dirtiest, and most overcrowded parts 
 of towns. Its diminution is attributed to the removal of personal 
 filth and overcrowding. The infection of typhus is communi- 
 cated only at close quarters, being transferred from the sick to 
 the healthy, probably by fleas. It occasionally is transmitted by 
 means of clothing. It is only within comparatively recent years 
 that typhus fever has been clearly distinguished from other fever, 
 notably enteric fever and relapsing fever. 
 
 Yellow Fever. — This is a very infectious malady which fre- 
 quently prevails in the West Indies, Mexico, Brazil, and on the 
 West Coast of Africa. Spain and Portugal are practically the 
 only European countries ever affected with it, and even there it 
 rarely spreads. It is essentially a disease of towns, particularly 
 tropical towns where insanitary conditions of every kind abound. 
 The precise cause of the disease is believed to be a specific 
 micro-organism which is present in the general circulation during 
 
NOTIFICATION ISOLATION. 35 1 
 
 the first three days of the disease. Persons long resident in places 
 where it prevails appear to have a remarkable immunity from 
 yellow fever ; new arrivals, on the other hand, are very readily 
 affected. Its incubation period varies from one to five days; 
 while its infectivity lasts some two to three weeks. There is no 
 evidence that yellow fever is spread by infected water or milk, but 
 only by means of a special mosquito which plays the same part in 
 respect of this disease as does another species in regard to 
 malaria. The mosquito which conveys the infection of yellow 
 fever from man to man is the Stegomyia fasciata, a species peculiar 
 to countries having a mean temperature of ioo° F. The pre- 
 vention of this disease resolves itself into an organized campaign 
 against mosquitoes. 
 
 Notification. — If, then, the foregoing is a true statement and 
 explanation of the nature and causes of infectious diseases, what 
 steps ought we and can we take on their occurrence, to prevent 
 their extension to others ? Expressed briefly, the special and only 
 precautions we can take to prevent the spread of infection are 
 notification, isolation, and disinfection. 
 
 By notification is meant the immediate intimation of the occur- 
 rence of every case of infectious disease to the medical officer of 
 health. In the majority of places in this country, notification is 
 by law compulsory on the part of the doctor attending the case, 
 and by whoever is in charge of the patient ; and on receipt of 
 this intimation, the medical officer of health or sanitary officer has 
 power to enforce such sanitary measures as may seem to him 
 necessary. Under the Infectious Diseases Notification Acts, 1889 
 and 1899, and various Regulations issued since, the following 
 diseases are scheduled as notifiable : Small-pox, scarlet fever, 
 diphtheria and membranous croup, enteric fever, cholera, plague, 
 measles, German measles, typhus fever, continued fever, relapsing 
 fever, puerperal fever, erysipelas, cerebro-spinal fever, polio- 
 myelitis, tuberculosis in all forms, ophthalmia neonatorum, acute 
 encephalitis lethargica, acute primary pneumonia, acute polio- 
 encephalitis, malaria, dysentery, and trench fever. Local autho- 
 rities have the power, subject to the sanction of the Ministry of 
 Health, to include other infectious diseases, such as whooping- 
 cough and chicken-pox. Valuable as it is, notification alone can 
 never stamp out infectious disease or check its spread ; it must 
 be supplemented by other action, that is, by isolation and 
 disinfection. 
 
 Isolation. — This, to be of the slightest use, needs to be 
 thorough, and means that, when infectious disease occurs in a 
 house, the patient or sick person must be completely separated 
 from the rest of the household. This can usually be satisfactorily 
 
352 INFECTION AND DISINFECTION. 
 
 carried out in most private houses, but is almost impossible in 
 small shops, workrooms, business premises, schools, or the crowded 
 dwellings of the poor. In these latter circumstances, the only 
 alternative is to remove the sick person to a fever or isolation 
 hospital, where he will no longer be the source of danger to 
 others that he is in his own home. Moreover, so excellently well 
 are these hospitals organized, the patient in all likelihood stands a 
 better chance of good treatment and recovery than if left to the 
 care of his own relations and friends. 
 
 In all efforts to isolate a case of infectious disease in a private 
 house, a room should be selected, if possible, on the topmost 
 floor, and no other room be used on that level. The door of the 
 room should, as far as practicable, be kept closed, and the room 
 itself have an open fire burning in it, with its windows also kept 
 open as much as possible. The room should be cleared of 
 all unnecessary furniture, carpets taken away, hangings and 
 curtains removed, and all stuffed or upholstered chairs replaced 
 by wooden ones, such as can be readily cleaned. The passages 
 and staircases leading to the infected room should be kept 
 as airy as possible, by leaving windows open day and night, 
 the idea being to so thoroughly dilute and ventilate the house 
 that any chance escape of infection from the sick-room may be 
 at once neutralized. 
 
 A special attendant or nurse should be detailed for the exclu- 
 sive service of the sick person, and all general communication 
 with the house reduced to an absolute minimum. Any articles 
 brought to the room should be left at the door, or given to the 
 nurse there, and no one allowed to enter except the nurse and the 
 doctor. Those in attendance on the sick should not mix with 
 the rest of the household, or, if this be unavoidable, the sick 
 attendants or nurses should invariably remove their dresses in 
 the sick-room, wash their hands and face, and then put on fresh 
 dresses, kept either outside or in an adjoining room; an alterna- 
 tive arrangement is to wear a cotton overall or wrapper, which 
 can be laid aside when leaving the sick-room. All crockery, such 
 as cups, plates, knives, forks, etc., necessary for the sick person 
 and the nurse must be kept exclusively for their use, and on no 
 account allowed to mix with others, or be passed into and washed 
 in the kitchen. The cleaning of these articles should be per- 
 formed by the nurse, and be done either in the sick-room, or 
 just outside. The dress of the nurse should be of linen ; woollen 
 and heavy stuff fabrics are inadmissible. The clothes worn by 
 the patient, and all bed-clothes, should, as soon as removed from 
 the person or bed, and, before being taken out of the room, be 
 soaked in a disinfecting solution, such as four fluid ounces of izal 
 
DISINFECTION. 353 
 
 mixed with one gallon of water, and afterwards in every case be 
 boiled and washed quite separately from the other household 
 linen. The same care needs to be observed in the treatment of 
 all discharges from the sick person. Thus all discharges from the 
 nose and mouth, which, in cases of diphtheria, scarlet fever, and 
 measles, are often both profuse and tenacious, should be wiped 
 away with pieces of rag, which should at once be burnt; no 
 handkerchiefs should be used; if they are, they must be burnt 
 also. The bowel discharges so frequent in enteric fever, cholera, 
 and diarrhoea should be received into bed-pans or utensils con- 
 taining some disinfectant, such as corrosive sublimate solution 
 (i in iooo), carbolic acid (5 per cent.), or izal (5 per cent.), well 
 stirred up, left for a quarter of an hour for the disinfectant to act, 
 and either burnt, buried, or discharged down the closet ; if the 
 latter is done, it should be well flushed afterwards. 
 
 As concerns the length of time isolation should be maintained, 
 we may say that it should be commenced so soon as the case is 
 suspected to be infectious, and continued until the doctor says 
 the sick person is safe to mix with others. It has already been 
 explained that this period will vary. Thus enteric fever, diarrhoea, 
 and cholera cases need to be isolated until the bowel discharges 
 become natural ; whooping-cough for quite two months ; small- 
 pox and scarlet fever until the skin ceases to give off branny 
 scales or scabs — this is rarely in less time than six weeks ; typhus, 
 diphtheria, and measles need isolation usually for a month ; while 
 mumps and chicken-pox for about two weeks. 
 
 Disinfection. — Allusion has already been made to the use of 
 disinfectants in the management of infectious diseases, especially 
 as an essential procedure to guard against their spread. Possibly 
 with reference to no single matter concerning sickness and in- 
 fection is there a greater amount of ignorance and misunder- 
 standing among the public than on that of disinfection and 
 disinfectants. The term " disinfection " means the destruction of 
 the particular germ or micro-organism upon which any infection 
 depends, and the expression " disinfectant " is applied to any 
 substance which can so kill and destroy infection. Unfortunately, 
 many people regard disinfection as meaning, not so much the 
 killing and destroying of germs, as the removing, covering, and 
 destroying of unpleasant smells, or, at most, the arresting and 
 impeding of putrefaction and the growth of microbes. While the 
 first is carried out by a disbifectant, the second depends on the 
 action of a deodora?it, and the third upon what is termed an 
 antiseptic. A substance which is a deodorant or antiseptic is not 
 necessarily a disinfectant, neither is a disinfectant of necessity a 
 deodorant. As a rule, of itself a bad smell does no harm, but it 
 
 N 
 
354 INFECTION AND DISINFECTION. 
 
 is of importance as indicating the existence and the presence of 
 microbes ; the mere smell can usually be disguised, removed, or 
 hidden by such deodorants as eau de Cologne, camphor, sanitas, 
 or even tobacco smoke ; but these would all be useless as means 
 of removing or destroying the germs which are the cause of the 
 bad-smelling gases. Similarly, commencing putrefaction is checked 
 by an antiseptic like Condy's fluid, but this fluid cannot kill and 
 destroy the living infective matter or germs of disease, and is, in 
 consequence, in no sense a disinfectant. 
 
 In actual practice, disinfection proper is largely aided by the 
 preliminary removal of infection by the scraping and stripping of 
 paper from walls, the washing and sweeping of floors, to say 
 nothing of air perflation, and the washing, beating, shaking, and 
 exposure of clothes. These procedures, excellent in their way, 
 are uncertain and incomplete ; the destruction of germs, or true 
 disinfection, is only attainable by either heat or chemical means. 
 For articles of small value, the safest plan is to burn them, but 
 when this cannot be done disinfection is best secured by exposing 
 them to either dry or moist heat. Experiments have shown that 
 the highly resisting spores of bacilli are destroyed by an exposure 
 for four hours to hot air at a temperature of 284 F., while steam 
 at 212 F. killed them in five minutes. Everyday experience of 
 disinfection shows that infective matter, to be destroyed, is rarely 
 freely get-at-able or freely exposed, but lies enclosed in clothes, 
 pillows, or beds, which are extremely bad conductors of heat. 
 Unless raised to a heat which injures the fabric, hot dry air is 
 unable to penetrate into the centre of non-conducting materials 
 like blankets, beds, etc., and is in consequence unable to raise 
 their deeper or central parts to sufficiently high a heat to destroy 
 any germs lodged there. The prevalent idea of disinfecting 
 articles of clothing by an exposure to dry heat in an oven is 
 most mischievous and unsound, because, without the risk of 
 injuring the materials or fabrics, no greater heat than 220 F. 
 can be employed, and this temperature, unless maintained for 
 something like eight to ten hours, is incapable of destroying in- 
 fection. Hot air moistened with steam is somewhat better than 
 hot dry air, but much inferior in both penetrating and germ-killing 
 power to steam, either superheated or saturated. Steam under 
 pressure rapidly penetrates into the interior of articles, where 
 undergoing condensation it imparts its latent heat to them. 
 
 Saturated steam has its temperature the same as, or near to, 
 that of the boiling-point of the liquid from which the steam is 
 derived, so that the steam condenses on very little cooling. 
 Superheated steam, on the other hand, is steam that has had its 
 temperature raised above that of the boiling-point of the liquid 
 
DISINFECTION. 355 
 
 from which the steam is produced, so that it must be cooled 
 down through several degrees of temperature before it condenses. 
 It is, in fact, dried steam, and acts like hot air, the heat passing 
 by a process of conduction. The difference between these two 
 forms of steam depends upon the quickness with which condensa- 
 tion takes place. The saturated steam condenses on very little 
 cooling, and therefore penetrates rapidly into articles, whereas 
 the superheated steam is not so penetrating because there is no 
 immediate condensation. The power of saturated steam to 
 penetrate into fabrics may be explained as follows : — Under 
 ordinary pressure, when water boils the temperature is 212 F., 
 and to convert this boiling water into steam a still greater heat is 
 needed, although the temperature of steam itself is only 212 F. 
 This extra heat has been absorbed and stored away by the steam, 
 and is in a condition known as latent heat, with the result that 
 when steam is condensed back into water by contact with any 
 cold surface the latent heat is given up again. Suppose a blanket 
 is being exposed to the action of saturated steam : the steam 
 enters its interstices and is there condensed, giving off at the 
 same time its latent heat, which assists in warming the blanket. 
 Further, when steam condenses to water, it contracts and occupies 
 a much smaller space (roughly 1 3 l ) than that previously occupied. 
 The result is that a vacuum is formed, and more steam rushes in 
 to fill it, to undergo in its turn condensation and contraction. 
 In this way every part of the blanket is attacked. The same, of 
 course, applies to mattresses and other fabrics : in fact, all bulky, 
 badly conducting articles are, in this way, penetrated thoroughly 
 by the steam, more especially if it be from time to time let off 
 and reapplied, or used in the form of current or moving steam, 
 so as to displace the cold air remaining in the interstices of the 
 article. Since penetration depends upon condensation, the dis- 
 infectant value of superheated steam does not much exceed that of 
 dry air. The amount of superheat which is generally given to the 
 steam in practice is not sufficient to cause it to act very differently 
 from saturated steam. The time required for disinfection by 
 steam varies with the organism to be destroyed, the bulk of the 
 infected articles, and the pressure of the steam employed. Expe- 
 rience indicates a temperature of from 115 to 120 C. for twenty 
 minutes to be alone trustworthy in all cases. 
 
 As practically applied in the present-day disinfecting machines, 
 steam may be saturated or superheated, and in either case in the 
 form of current steam that is in motion or confined under pressure. 
 A great advantage of current steam is that it favours penetration 
 by driving air out of the machine and out of the interstices of the 
 various articles and fabrics in it. A saturated steam disinfecting 
 
356 INFECTION AND DISINFECTION. 
 
 machine (working at a pressure of 10 lbs., and the steam having 
 a temperature of 240 F.) appears to be the best in practice, 
 whether from the point of view of expense, danger, or efficiency. 
 Such a machine is the so-called " Equifex." It consists of a 
 strong, thin elliptical chamber made of boiler plate, carefully 
 lagged on the outer side to prevent loss of heat by radiation, and 
 fitted at each end with a tight-fitting door. This chamber is fitted 
 with a light frame on wheels, on which clothing, etc., can be 
 suspended ; it is run out of the door for this purpose. The frame 
 being run in again, the door is closed and firmly fastened. 
 Steam, generated from an outside boiler, is conducted into the 
 interior of the chamber, and all the air therein carefully expelled ; 
 the articles within the chamber are kept exposed to this steam at 
 a pressure of about 10 lbs. for about twenty minutes, the steam 
 shut off. A blast of hot dry air is drawn through the chamber at 
 the last, so as to ensure the thorough drying of the articles which 
 have been exposed to the steam ; after this they are withdrawn. 
 The machine is fitted with gauges and thermometers, by which 
 the temperature and pressure inside may be definitely and exactly 
 told. No jacketing of the machine is necessary, as in the case of 
 those working with superheated steam : experience shows that a 
 uniform temperature can be obtained in all parts of the chamber, 
 together with a rapid and complete penetration of all bedding, 
 clothes, and other articles. Experiments show that a temperature 
 of 240 F. can be readily obtained in seven to ten minutes in the 
 centre of a blanket folded sixteen times by means of a machine 
 working with saturated steam at a pressure of 10 lbs. to the square 
 inch, over and above that of the atmosphere. Other experiments 
 made with a hot-air machine failed to obtain, under similar con- 
 ditions, a temperature higher than 190 F., and that only after 
 nine hours' exposure. In fact, hot air penetrates very slowly, 
 the heat passing by conduction, much as it does in the case of 
 superheated (dried) steam. Saturated steam, then, is the ideal 
 disinfectant, giving, under a pressure of 10 lbs. to the square 
 inch, a temperature of 240 F. (115 C), which is sufficient, by a 
 contact of twenty minutes, to kill all germs and their spores. 
 
 The employment of superheated steam is secured by one of 
 two ways : (1) By a jacket around the disinfecting chamber, in 
 which outer jacket steam is kept at about double the pressure and 
 some 30 F. hotter than that within the inner chamber, whereby 
 the latter steam is kept constantly dried or superheated ; machines 
 of the older Washington-Lyon patterns are representative of this 
 type. (2) By generating steam from a saline liquid, whose boiling 
 temperature under atmospheric pressure is about 225 F., or much 
 in excess of that of ordinary water under natural pressure. This 
 
DISINFECTION, 357 
 
 is the principle of Thresh's disinfecting stove. This latter 
 apparatus is effective, employing steam in the current state, and 
 has the advantage of being much less costly than some other 
 machines. In stoves using steam confined under pressure, the 
 steam should be allowed to escape, from time to time, as this 
 serves to displace the air in the centre of bulky articles, which air 
 is often compressed otherwise. The greatest effect is, of course, 
 produced when the steam has been under very high pressure. 
 
 The use of steam for disinfection, either superheated or satu- 
 rated, cannot be carried out in ordinary houses, but the majority 
 of health authorities now have some form or other of steam 
 disinfecting apparatus, and are prepared to remove, disinfect, and 
 return clothing, bedding, etc., free of charge. In sending articles 
 for disinfection, by either dry or moist (steam) heat, it must not 
 be forgotten that heat has a certain effect upon the colour and 
 texture of fabrics exposed to it. Thus leather is shrivelled up and 
 spoilt by steam, while hot dry air makes leather dry and brittle. 
 Cotton and silk are not injured by steam at all, but, unless care- 
 fully regulated, are damaged by dry heat. Flannels, blankets, and 
 woollen goods suffer little by either dry or moist heat, beyond 
 some loss in colour ; dyes appear to suffer little by either process. 
 In the case of bedding, the hair or feathers in mattresses or 
 pillows must always be taken out and loosened, before exposing 
 them to disinfection by heat. 
 
 The great drawback to the use of dry heat is the variation 
 in temperature at different parts of the disinfecting chamber ; 
 and its effects upon fabrics vary according as to whether they 
 are placed on the floor, or near the sides, or hung in the central 
 or upper parts. With the use of steam, this variability of heat 
 is not met with. 
 
 In circumstances where no means exist for disinfecting bulky 
 articles of clothing and bedding by these methods, they should, 
 if possible, be destroyed by burning ; failing that, they should 
 be boiled, or at least be allowed to soak for twenty-four hours in 
 some disinfecting liquid, such as one of the following : (a) Izal, 
 5 parts to ioo of water, (b) Chloride of lime, 2 ozs. to 1 gallon 
 of water. (c) Carbolic acid, 5 parts to 100 of water, (d) Bichloride 
 of mercury, \ oz. ; hydrochloric acid, 1 oz. ; aniline blue, 5 grs., to 
 3 gallons of water. 
 
 Without doubt, bichloride of mercury is the most powerful 
 disinfectant ; it surfers, however, from the disability of being very 
 poisonous, deleteriously affects metals, and forms insoluble com- 
 pounds with organic matter. Stains are apt to be fixed by it. 
 For these reasons, we think the practical utility of the bichloride 
 of mercury as a general disinfectant is limited and inferior to 
 
358 INFECTION AND DISINFECTION. 
 
 carbolic acid, izal, cyllin, the various cresols, and other proprietary 
 preparations of the higher phenols now in the market. 
 
 Many of the so-called disinfectants in common use are 
 absolutely unreliable, particularly when unduly diluted. Large 
 numbers of people appear to regard Condy's fluid as a disinfectant. 
 It is merely a solution of the permanganate of soda or potash, 
 which, as a powerful oxidizing agent, though capable of sweeten- 
 ing foul discharges from wounds, is nearly powerless to destroy 
 the germs of infection. Clothes and bedding, therefore, which are 
 merely dipped or soaked in it cannot be said to be disinfected. 
 Chloride of zinc, in the form of Burnett's fluid, is much more 
 powerful. It is well adapted for disinfecting cholera and enteric 
 discharges, but is less so than either carbolic acid or the bichloride 
 of mercury. Sulphate of iron, or green copperas, if used in the 
 strength of i lb. to a gallon of water, makes a valuable dis- 
 infectant for drains, but owing to its staining powers, is unsuited 
 for soaking linen or clothing. Sanitas, chloralum, eucalyptus, 
 camphor, thymol, boric acid, and iodoform are not true dis- 
 infectants, or only so in the weakest manner. They are unfitted 
 for the disinfection of fabrics and clothing. 
 
 Fumigation. — All attempts to disinfect clothing, bedding, 
 etc., by mere fumigation at home should be discouraged, as it 
 rarely succeeds in destroying the germs of infection. Far too 
 great importance is attached by people to fumigation, and to 
 the influence of chemical vapours as purifiers and means of 
 disinfecting the air. The truth is, aerial disinfection is more or 
 less of a delusion unless the air be rendered unfit to breathe. 
 We should not aim at purifying old or fouled air, but rather 
 renew it by free dilution and ventilation. It is, even in these 
 days, no uncommon thing to see people placing saucers of 
 Condy's fluid or carbolic acid about sick-rooms, or spraying 
 the air with vinegar, terebene, eucalyptus, and various other 
 volatile agents, under the impression that they are disinfecting 
 the air. All these efforts are useless, and give a false sense of 
 security, which at the same time diverts attention from more 
 efficient measures, especially those directed to secure adequate 
 disinfection of clothing and bedding to which, rather than to the 
 room itself, infection attaches. They, moreover, are based upon 
 a misconception. We cannot and do not need to disinfect the 
 air of a room or given space, neither can we disinfect the walls 
 and component structural parts of a building. To attempt to do 
 so is a waste of time and expensive materials. 
 
 It cannot be too clearly understood that while a room is 
 occupied it is quite impossible to kill and destroy any infection 
 or disease germs floating about in its contained atmosphere, with- 
 
FUMIGATION. 359 
 
 out also killing those persons living in the room. But once the 
 chamber is vacated we can, with some hope of success, endeavour 
 to remove microbes and their spores deposited in its dust on 
 floors, ledges, or adhering to its walls and ceilings, by a combi- 
 nation of scrubbing, scraping, spraying, and the evolution of 
 deterrent gases. The most reliable chemical agents used for 
 these purposes are formaldehyde and sulphur dioxide. Their 
 use in this way is not disinfection. At best it merely cleans and 
 deodorizes. Vermin such as bugs escape their action by retreat- 
 ing into shelter, and as ordinarily employed these gases are a 
 fraud upon the public. Their use should be discouraged. 
 
 Formaldehyde may be used either in watery solution and 
 applied to walls and surfaces in the form of a spray, or it may 
 be employed as a vapour. The commercial form of formaldehyde 
 is formalin, which contains 40 per cent, of formaldehyde. Two 
 per cent, of formalin, or 3*25 fluid ozs. to a gallon of water, to 
 which is also added 3 ozs. of glycerine to prevent polymerization, 
 applied as a spray, is very effective in the cleansing of walls, 
 floors, ceilings, and other parts of houses or rooms. This state- 
 ment, however, only holds good provided an efficient atomizer or 
 spray be used, and that great care is taken to see that the liquid is 
 brought into complete contact with the whole surface and no bare 
 patches left. Employing the above formula, we have found that, 
 for effective cleansing of walls, etc., at least two gallons of the 
 solution must be used for each thousand square feet of surface to 
 be sprayed. To avoid making streaks or marks on the wall, the 
 spraying must be begun at the bottom and continued from below 
 upwards. 
 
 Formaldehyde vapour, for use as a gaseous deodorizer or 
 cleanser, is usually obtained by volatilizing the solid form of 
 formaldehyde or para-formaldehyde by means of heat in the 
 presence of aqueous vapour in a special lamp. There are various 
 forms of apparatus for its production, the more common being 
 the Alformant lamps of Schering, in which tablets of paraform 
 are burned. It is claimed that one of these tablets, when vola- 
 tilized, is sufficient for 100 cubic feet of space ; our experience 
 indicates that at least five tablets per 100 cubic feet should be 
 converted into formaldehyde vapour, and we recommend not less 
 than this quantity to be used. 
 
 Various other forms of vaporizers for formaldehyde have been 
 suggested, but the greater number fail to secure sufficient pene- 
 trative power. Perhaps the best of the kind is Trenner's, which 
 in our hands has certainly yielded good results. It works from 
 outside the door of the room to be cleansed, vrithout pres- 
 sure, and automatically. It consists of a heavy cvopper retort 
 
3 6 ° 
 
 INFECTION AND DISINFECTION. 
 
 constructed on the lines of a modern tubular boiler, and from 
 which a known quantity of formaldehyde solution can be rapidly 
 and conveniently vaporized. The emerging vapour is practically 
 superheated by the escaping products of combustion from the 
 spirit-lamp beneath, and readily conducted by the elongated 
 
 neck of the retort to the interior 
 of a room, by passing the nozzle 
 through the keyhole of a closed 
 door. No attention is required 
 after filling the apparatus and light- 
 ing the lamp, which, containing a 
 definite amount of spirit, is allowed 
 to burn itself out. We have found 
 it unnecessary to hermetically seal 
 small crevices or cracks, as the for- 
 maldehyde gas and water vapour 
 are so highly superheated, evolved 
 so rapidly, and in such volume, that 
 penetration into all parts of the en- 
 closed space is secured with a maxi- 
 mum germicidal action on all ex- 
 posed surfaces within the room. 
 The main essential for success is 
 the vaporization of a sufficient 
 volume of formaldehyde solution in 
 relation to the size of the room. 
 From our experience, this may be 
 put at not less than nine fluid 
 ounces (250 c.c.) of formalin, with 
 1 per cent, of glycerine, for each 
 thousand cubic feet of space. In the 
 case of very large rooms, it may be 
 necessary to employ two or more 
 of these vaporizers. One of these lamps is sufficient for a space 
 of 4000 cubic feet. It must be remembered that the vapour of 
 formaldehyde is both pungent and irritating. Other efficient 
 vaporizers working on similar principles are the " Torrent " and 
 the " Lingner." 
 
 Under circumstances in which a special vaporizer is not 
 available, the following process will be found efficient. Pour 
 formalin quickly upon fine crystals of potassium permanganate 
 contained in a suitable metallic vessel ; a vigorous ebullition takes 
 place in a few seconds accompanied by the generation of steam 
 and free formaldehyde. The reaction is over in a few minutes, 
 and by using two parts of the formalin to each part of the per- 
 
 Fig. 61. — Trenner's formaldehyde 
 disinfector. 
 
FUMIGATION. 361 
 
 manganate the residue* in the vessel is left almost dry. We have 
 submitted this method to a large number of experimental obser- 
 vations, and found it to be effective, simple, and free from risk. 
 For a space of 1500 cubic feet, 285 grammes, or 10 ounces, of the 
 permanganate, and 570 cubic centimeters, or 1 pint, of formalin 
 are needed, the re-agents being mixed or added the one to the 
 other in an ordinary galvanized iron pail ; the permanganate 
 must be put in first, and the formalin poured on to the crystals. 
 
 A similar result can be obtained if a mixture of one part by 
 weight of paraform with two parts by weight of bleaching powder is 
 stirred with three parts of water : for a space of 1500 cubic feet 
 125 grammes of paraform, 250 grammes of bleaching powder, 
 and 400 grammes of water generate sufficient active formaldehyde 
 with slight traces of chlorine to secure cleansing of all exposed 
 surfaces. The principle of generating formaldehyde by these two 
 methods underlies the various reagents sold under the name of 
 " Autan." It is assumed that, in practically applying these 
 methods for the purification of a room, all doors, windows, 
 chimneys, cracks and crevices are closed and maintained in that 
 state for at least four hours. 
 
 Sulphur dioxide may be employed for fumigation and surface 
 purification in the absence of means for generating formaldehyde. 
 The dioxide of sulphur or sulphurous acid is most conveniently 
 generated from tubes of the liquefied gas. One of these tubes 
 suffices for a space of 1000 cubic feet. If these tubes are not 
 available, the sulphur dioxide can be readily generated by break- 
 ing up roll sulphur into pieces of the size of a hazel nut placing 
 these on a metal plate inside a large metal basin or pail. If 
 some methylated spirit be poured over the sulphur, the latter will 
 ignite readily. Not more than one pound of sulphur should be 
 placed in any one dish, and for a space of 1000 cubic feet, at 
 least three pounds of sulphur must be burnt. The great advan- 
 tage of sulphur dioxide as a gaseous purifier is the simplicity 
 of its generation, but it is somewhat unreliable in dry or cold 
 atmospheres, and, like formaldehyde, evinces its maximum effect 
 in a percentage humidity of 70, and at a room temperature of 
 70 F. In spite of these limitations, if precautions are taken to 
 reduce leakages to a minimum, purification of surfaces by fumiga- 
 tion with either of the above-mentioned gases will destroy most, 
 if not all, of the freely exposed and less resistant micro-organisms ; 
 more than this cannot be expected. 
 
 Of the many other reagents now in the market, and popularly 
 regarded as disinfectants, the majority are really not so at all, 
 unless used in very concentrated solutions ; they are merely 
 deodorants, or at most antiseptics or means of checking and 
 
362 INFECTION AND DISINFECTION. 
 
 delaying putrefaction. Much of this difficulty arises from the fact 
 that there is no official control over the sale of disinfectants, 
 other than that set forth in the Privy Council Orders of July 27, 
 1900, and June 5, 1902. The first order permits the sale, 
 without control, of liquids containing less than 3 per cent, of 
 phenol or its homologues as disinfectants, on the ground that 
 such a fluid is not a poison within the meaning of the Pharmacy 
 Act, 1868. In the second order, it is stated that liquid dis- 
 infectants containing scheduled poisons (which for present pur- 
 poses are practically phenol or its homologues, in solutions of 
 more than 3 per cent., and corrosive sublimate) shall be sent out 
 in distinctive bottles. It is clear that these orders exercise no 
 control over the sale of undoubted disinfectants such as mercuric 
 iodide and formaldehyde. This anomalous state of affairs is 
 largely due to the absence of any organized system of standard- 
 izing disinfectants. Any attempt at standardization must be 
 based upon a bacterial rather than a chemical determination of 
 efficiency, as although the strength of a preparation of phenol or 
 its homologues can be ascertained with accuracy, there are many 
 other equally good disinfectants which do not depend upon these 
 acids for their germicidal efficiency. We hope to see this matter 
 placed upon a satisfactory basis at no distant date. The difficulty 
 is to determine what shall be the unit of comparison. Pure phenol 
 has been suggested, and it is probable that this will be the most 
 convenient standard to adopt, and that the strength or efficiency 
 of any disinfectant will be expressed in multiples of carbolic acid 
 performing the same work, the ratio, so obtained, being called 
 the phenol coefficient. 
 
 Practical Disinfection. — Although under the preceding head- 
 ings the practical utility of the various means of disinfection has 
 been more or less clearly indicated, it may be of value to briefly 
 summarize these very necessary measures in respect of discharges 
 or excreta, clothing, bedding, furniture, rooms, and drains, gullies, 
 and refuse. 
 
 Of excreta and discharges. — These should be received into a 
 vessel containing either carbolic acid solution (1 in 20) or izal 
 solution (1 in 20) or cyllin (1 in 50), with the application of a 
 further quantity of the disinfectant directly afterwards, sufficient 
 to cover the mass. The whole should then be intimately mixed 
 by stirring with a stick. In cholera, enteric fever, and dysentery, 
 sterilization of the evacutions by steam heat is advisable if it can 
 be done. In cholera the vomited matter should be treated in the 
 same way as the stools. In diphtheria, scarlet fever, measles, 
 whooping-cough, and phthisis, great care needs to be taken that 
 all discharges from mouth or nose, and rags or handkerchiefs 
 
PRACTICAL DISINFECTION. 363 
 
 soiled by them, be adequately subjected to disinfection on these 
 lines. 
 
 Of clothing and bedding. — All articles of little value should be 
 burnt. Small articles may be boiled for an hour or longer. Bulky 
 articles, such as blankets, bedding, mattresses, etc., should be 
 subjected to moist heat in a proper disinfecting apparatus. In 
 default of special appliances, sheets and clothing may be soaked 
 in carbolic acid (1 in 20), or izal (1 in 20), or chloride of lime 
 (2 ozs. to gallon), or cyllin (1 in 100), or formalin (2 per cent.), or 
 perchloride of mercury (1 in 1000) for twelve hours, and then 
 boiled and washed. 
 
 Of furniture a?id rooms. — This can only be carried out 
 effectually when the room is unoccupied; therefore the first 
 essential is evacuation, next all articles that can be disinfected 
 by moist or dry heat or by soaking in some chemical disinfectant 
 should be removed, and treated accordingly. The structural 
 parts of rooms such as walls, ceilings, and floors cannot be dis- 
 infected. The most that can be done is to clean them. The 
 same is true of articles of furniture. If an attempt to cleanse by 
 gases is to be made, then all windows, chimneys, and orifices 
 having been closed as tightly as possible, and all cupboards and 
 drawers opened and exposed, the space or chamber be fumigated 
 in presence of moisture with either formaldehyde, or sulphurous 
 acid for at least four hours. 
 
 On re-entering, open all doors and windows, and strip the 
 walls of paper, burn the pieces, have the ceiling well limewashed, 
 and scrub all floors, all woodwork, and furniture with either plain 
 hot water and soft soap, or with bichloride of mercury (1 in 1000) 
 or with formalin (2 per cent.). 
 
 In many cases, adequate disinfection will be secured by free 
 perflation of air, and, in place of fumigation, the free use of a 
 spray of formalin in the proportions already stated to the surfaces 
 of walls and furniture. We are disposed to consider the routine 
 spraying of walls, or the fumigation of rooms with disinfectants as 
 largely a waste of time and reagents. The chief risk of infection 
 in these places attaches to clothing, bedding, and curtains ; if 
 these articles be disinfected by means of steam, the actual room 
 or place can be rendered sweet and wholesome by free ventilation 
 and thorough washing and scrubbing with soap and hot water. As 
 this fact becomes more generally appreciated, a considerable 
 modification in present day practice may be expected. 
 
 Of drains, gtillies, and refuse. — The actual disinfection of 
 drains and other places which receive offensive matters is impos- 
 sible; the most we can hope to do is to deodorize. This can be 
 done either by the liquid disinfectants already mentioned, or by 
 
364 PARASITES. 
 
 solid chemical reagents, such as lime, quicklime, and chloride of 
 lime. Even dry earth and charcoal will be found useful. So too 
 will the various carbolic powders, which are mainly combinations 
 of one or other of the phenols with either lime, silica, or alumina. 
 Sulphate of iron (1 lb. to gallon) is a valuable agent for drain and 
 gully deodorization. Free flushing with water is probably better 
 than the application of any disinfectant. 
 
 CHAPTER IX. 
 PARASITES. 
 
 In addition to the various micro-organisms referred to in the 
 last chapter, and which it was explained are now regarded as 
 the cause of the different infectious or specific diseases, the 
 human body is liable to the attacks of various other organisms. 
 These organisms are both vegetable and animal, and according 
 to the nature and function of the respective parts of the body 
 which they attack, give rise to diseased conditions of varying 
 severity. It is customary to speak of these living organisms, 
 which are dependent upon or adventitious, as it were, to the 
 human body as parasites. 
 
 The vegetable group of human parasites are almost exclusively 
 met with on external parts of the body, and being of the nature 
 of minute fungi, or moulds, they give rise to skin diseases of a 
 more or less contagious character. Such are the various kinds of 
 ringworm, chloasma, and thrush. 
 
 Ringworm is the popular name for a large group of skin 
 diseases which have a certain family resemblance to each other, 
 in that they often spread in the form of a ring or circle. All these 
 diseases are produced by species of fungi, which, as a rule, have 
 strong predilections for the scalp and other hairy parts of the 
 body. Being intensely infectious or contagious, these vegetable 
 parasitic diseases are readily transferred from one person to 
 another. Ordinary ringworm is sometimes epidemic in schools, 
 spreading from child to child by contact or contagion. The 
 
OTDIUM ALBICANS. 365 
 
 typical disease consists of circular patches varying from a six- 
 pence to a five-shilling piece in size or larger, having a slightly 
 raised or scurfy surface, the hairs on which are dry, brittle, lustre- 
 less, and broken off close to the scalp. This condition is caused 
 by the fungus attacking the hairs, a fact easily shown by soaking 
 a diseased hair in weak potash solution, and then examining it 
 under the microscope, when it will be seen that the hair is invaded 
 to a greater or less degree by the fungus called the Trichophyton 
 tonsurans. Ringworm of the body is marked by the occurrence 
 of red, scaly, itchy, and circular patches, and is excited by the 
 same fungus as occasions ringworm of the scalp. 
 
 Favus, or scald-head, is another form of ringworm, caused by 
 the fungus Achorion Schon/einii, and known by the presence of 
 dry, light, cup-shaped crusts, out of which a hair sticks, and 
 made up of fungus elements. Owing to the highly contagious 
 nature of these skin diseases, care needs to be taken that they 
 are recognized early, and treatment adopted. This consists in 
 the killing of the parasite by means of repeated applications of 
 iodine, or the use of germicides, such as corrosive sublimate. All 
 infected hats, caps, or clothing should be destroyed by burning. 
 
 Microsporon Furfur is the cause of a skin disease marked by 
 fawn-coloured patches, occurring in the parts covered by flannel, 
 especially the front of the chest and root of the neck, and known 
 as chloasma. These are often raised and occasionally itchy. The 
 liberal application of soap and water usually suffices to remove 
 this parasite. 
 
 Oidium Albicans is a mould which causes thrush, or the 
 greyish-white circular patches seen in the mouths of young and 
 feeble children, especially when artificially or improperly fed. 
 This mould is probably identical with the oidium of milk, since 
 the use of turned milk or a dirty feeding-bottle or tube by a 
 child is almost invariably followed by the appearance of this 
 parasitic growth inside the child's mouth. The occurrence of 
 these patches indicates, not only that a child is not in the best 
 of health, but also that greater care is needed to be observed 
 as to the freshness of the milk or food and the cleanliness of the 
 feeding-bottles. Every speck or patch of this oidium should be 
 wiped out of the child's mouth, by either the finger or corner of 
 the handkerchief, and the gums and insides of the cheeks washed 
 over with either glycerine and borax, or with a solution of 
 chlorate of potash. 
 
 The animal parasites which attack man are unicellular organ- 
 isms either belonging to the protozoa, or insects which burrow 
 into and attack the skin, or worms which infest the blood and 
 internal organs. As will be seen subsequently, the most remark- 
 
366 PARASITES. 
 
 able feature in animal parasites is the fact that their parasitism 
 only represents a single phase in the life of the animal, and that 
 while a few parasites, notably the parasitic insects, do not attain 
 to sexual maturity until they have commenced to lead a free 
 existence, the greater number of them, especially the worms, 
 attain sexual maturity while in their parasitic stage, and therefore 
 reproduce themselves in the body of their host. 
 
 Fig. 62. — Trypanosomes. 
 
 Of the protozoa, parasitic to man, the more important are the 
 following : — 
 
 Amoeba Dysenteriae is an oblong or round body consisting of 
 an outer pale homogeneous protoplasmic substance enclosing a 
 somewhat greenish highly refractive mass containing vacuoles 
 and a nucleus. These amoebae, which are the cause of certain 
 forms of dysentery, vary in size from 0*008 to 0*05 millimetre. 
 They commonly reach man by means of polluted drinking water, 
 attach themselves to the mucous lining of the large intestine, 
 where they give rise to ulcers and severe symptoms. Occa- 
 sionally, they may penetrate to the liver and cause abscesses io 
 that organ. 
 
 Trypanosomes are a species of protozoa characterized by the 
 possession of a longitudinal undulating membrane, which takes 
 its origin posteriorly from a mass of chromatin, and terminates 
 anteriorly in a whip-like lash or flageHum (Fig. 62). The trypano- 
 
SPIROCHETES. 367 
 
 somidae occur in fish, amphibia, reptiles, birds, and mammals. 
 Most of these are incompletely known, and only recently a few 
 forms have acquired great importance from the fact that they 
 cause more or less serious disease in man and animals. Thus, 
 T. evansi is the parasitic trypanosome causing a disease called 
 surra in horses in India ; other varieties cause similar disease among 
 horses in Algeria, Central and South America. T. brucei is the 
 highly pathogenic trypanosome of tsetse-fly disease or ngana, an 
 infection of cattle in South Africa conveyed by means of a species 
 of glossina or tsetse-fly. T. vgandietise is the notorious parasite 
 found in the cerebro-spinal fluid of cases of sleeping sickness. It 
 is conveyed from person to person by means of a biting fly known 
 as glossina palpalis. These are the more important trypano- 
 somes, but there are several others known to be associated with 
 certain obscure diseases of animals. 
 
 The life history of the trypanosomes is imperfectly known, but, 
 with one exception, all the species which have been investigated 
 have a second host, which is an invertebrate of some kind. The 
 exception is the T. equiperdnm of a disease in horses known as 
 dourine, in which the parasite is said to pass direct from a sick 
 animal to a healthy one. The intermediate host in the other cases 
 is a blood-sucking invertebrate, and in this host alone does the 
 sexual cycle take place. 
 
 Spirochetes. — This genus appears to be allied closely to the 
 trypanosomes, and some important parasitic forms have been 
 referred to it. These parasitic micro-organisms have the appear- 
 ance of minute slender threads, wavy or spirally twisted in form 
 (Fig. 63). The true type of this genius is S. plicatilis, which has 
 an undulating membrane, no trace of flagella, a blunt round end, 
 and a unclear apparatus of a thread-like nature. Among the more 
 important pathogenic members of this genus are the S. obermeiri 
 of relapsing fever conveyed from man to man by the bug ; 
 S. duttoni or the parasite of human tick-fever conveyed by the 
 tick ornithodoros moubata ; the S. pertenuis of yaws, and the 
 Treponema pallidum or infecting micro-organism of syphilis. 
 
 Leishmania. — Under this heading we refer to certain human 
 parasites which are still the subject of some controversy. These 
 are the so-called Leishman-Donovan bodies found in the spleen 
 and other organs in Kala-azar and oriental sore. These parasites 
 are typically intracellular, being found as ovoid or pyriform bodies 
 in leucocytes and cells of endothelial nature. When cultivated'in 
 suitable media and at moderate temperature, the Leishman- 
 Donovan bodies undergo changes which result in their becoming 
 flagellate organisms. Nothing is known of the natural develop- 
 ment of these parasites outside the human body, but it is suspected 
 
368 PARASITES. 
 
 that some form of arthropod like a bug or tick is the intermediary 
 host. It is not unlikely that there exists some minute spirillar 
 stage which is ultra microscopic. 
 
 Coccidium Hominis. — This is probably the same species as 
 attacks the intestinal epithelium of rabbits. The infection of man 
 by this parasite is associated with serious symptoms, such as fever, 
 
 Fig. 63. — Varieties of Spirochaetes. 
 A and B, Treponema pallidum. C, Spirochczta re/ringens. D, Spirochceta plicatilis. 
 
 diarrhoea, and enlarged liver. These parasites are minute spherical 
 bodies, rarely more than a millimetre in size, attacking the 
 epithelium of the bowel or the cells of the liver. Fortunately, 
 infection of man by these coccidia is rare, but in rabbits it is 
 fairly common. 
 
 Plasmodium Malarise. — Three varieties of this species parasitic 
 to man are recognized : P. malaria or the parasite of quartan 
 ague, P. vivax or the benign tertian parasite, and P. immaculatum 
 or the parasite of malignant tertian malaria. Other species of the 
 genus affect monkeys, birds, bats, and even reptiles. The life 
 cycle of the malarial parasite has been explained elsewhere, and 
 also its intimate association with a certain variety of mosquko, 
 which is its intermediate host. 
 
 Piroplasma. — In this family are included a number of 
 organisms which are parasitic to cattle and dogs, but only one 
 
SCABIES. 
 
 69 
 
 Fig. 64- — Acarus scabiei. 
 
 which is apparently parasitic to man. This is the P. hominis, the 
 cause of the tick fever of the Rocky Mountains. The parasites 
 are very minute pear-shaped forms occurring singly or in pairs 
 inside blood corpuscles. Very little is known regarding the life 
 cycle of the piroplasmata, but 
 the intermediary host in all cases 
 appears to be a tick. 
 
 Scabies, or itch, is caused by 
 the burrowing into the skin of an 
 insect called the Acarus scabiei 
 (Fig. 64). This burrowing excites 
 much itching and some rash. It 
 is the female itch insect which 
 thus burrows and causes the cha- 
 racteristic symptoms of this 
 disease; for, burrowing beneath 
 the cuticle, she lays her eggs at 
 the end of the burrow, where 
 they hatch, and the young insects 
 then commence to burrow afresh 
 in other directions. A very com- 
 mon place for itch to begin at is in the spaces between the 
 fingers, and from out of the burrows, here or elsewhere, the acarus 
 can be dug out by a needle, if carefully looked for. The irritation 
 which these insects set up is most intense, and often gives rise to 
 eruptions of pimples, blisters or pustules, which readily obscure 
 the true nature of the affection. Owing to the ready means by 
 which the itch insect can pass from one person to another, itch 
 is eminently contagious, and the greatest care needs to be taken 
 in separating those affected with the parasite from those who 
 are free, and too, the most careful disinfection of all clothing which 
 has been worn by the sufferer. For the actual cure of the itch, 
 sulphur ointment is the best remedy, but needs to be supple- 
 mented by scrubbing the skin with soft soap and hot water. 
 This scrubbing removes the loose scurf or scales of the skin, 
 and helps the action of the sulphur by exposing the insect in its 
 furrows. 
 
 The louse, or pediculus, may infest either the hair of the head 
 or the body, in both of which parts it gives rise to characteristic 
 irritation. Lice in the hair are quickly killed by saturating the 
 hair with an ointment of corrosive sublimate ; but a difficulty 
 often exists in destroying their eggs or nits, which adhere to the 
 hairs by means of a gummy matter. This can usually be dis- 
 solved by means of methylated spirits, and the nits detached by 
 careful combing. The constant use of warm baths, soap, and 
 
37° 
 
 PARASITES. 
 
 Fig. 65. 
 
 -Pulex penetrans. 
 and male. 
 
 Female 
 
 scrupulous cleanliness are essential aids to keeping away the 
 pediculi. The clothes of those affected with the body variety 
 
 require exposure for some hours 
 to a dry heat of not less than 
 220 F., or else to be treated by 
 one or other of the disinfection 
 methods as detailed in the last 
 chapter. 
 
 Fleas and bugs are, in a sense, 
 parasitic, but possibly less so than 
 a special variety of flea met with 
 in some parts of the tropics, called 
 the chigoe, or Pulex penetrans (Fig. 
 65). These insects give rise to 
 considerable pain and irritation, 
 accompanied by swelling of the 
 parts attacked. It is only the 
 female insect which gives rise to 
 these symptoms. While the male 
 retains the ordinary form and habits 
 of a flea, the female bores her way 
 into the skin of the foot in man, 
 dogs, and other animals, and be- 
 comes, by the enormous development of the ovary, a simple motion- 
 less bladder embedded in the flesh, around which, in course of 
 time, when the eggs have to be extruded, a certain amount of 
 inflammation arises. 
 
 Fleas, Bugs, Ticks, and other insects are not only of interest 
 because they bite, suck blood, and are parasitic on man and 
 animals, but on account of the fact that they serve as hosts for 
 the conveyance of germs and other parasites from animals to man 
 and from man to man. Thus Pulex cheopis or the common flea of 
 rats in India is concerned in the transmission of plague bacilli, 
 not only from rats to rats, but from these and other infected 
 animals to man. 
 
 As regards bugs and ticks, especially the latter, considerable 
 evidence has accumulated showing that these arthropods are 
 intimately associated with the spread of disease. Thus, Rhipi- 
 cephalus annulatus and R. Appe?idiculatus are two ticks common 
 in Texas, Queensland, and South Africa, which transmit the germs 
 of red-water fever among cattle ; in a similar manner another tick, 
 Dermacentor reticulatus, is associated with the spread of Rocky 
 Mountain fever in the Western States of North America. Other 
 ticks convey corresponding diseases among sheep and dogs, while 
 the Ornithodoros moubata is a tick found in the Congo Free State 
 
FLEAS, BUGS, AND TICKS. 37 1 
 
 and Sudan which conveys the infection of relapsing fever from 
 man to man. 
 
 The life history of a tick is briefly as follows : The female 
 deposits her eggs in masses on the ground, and then gradually 
 shrivels up and dies. The favourite place for ovi-deposition is on 
 grass or coarse herbage. The egg-stage varies from eight to 
 twenty-two weeks, and then gives rise to the larval form. These 
 larvae are six-legged and soon crawl up grasses and plants, waiting 
 to become attached to some passing host. The larval ticks feed 
 upon the blood of the host and when repleted fall to the ground. 
 Here they moult and change to the nymph or pupal stage, which 
 has four pairs of legs. The pupa acts just as the larva, crawling 
 up grass and there waiting to regain a host. Having done so and 
 gorged blood, the nymph falls to the ground and remains there 
 a variable time, sometimes as long as three months. It then 
 moults and becomes an adult male or female tick, which, regain- 
 ing a host, feeds on its blood and then repeats the cycle. Ticks 
 may live a long time away from the host, provided they have 
 moisture. There seems to be no pressing necessity for a tick to 
 secure a host, for even if starved and growth be arrested, the 
 longevity is marked ; on the other hand, feeding on a host appears 
 to be essential for growth and exuviation, and under these favour- 
 able conditions life is often brief. Although in the majority of 
 species of ticks, each individual must find a host three times in 
 the course of its existence, namely, in its larval, nymphal, and 
 adult stages, there are notable exceptions to this rule. Thus, 
 Rhipicephalus annulatus effects both moults upon one host ; 
 R. bursa makes its first moult on the host and its second on the 
 ground, thus needing a host twice; R. Appendiculatus effects 
 both moults on the ground, thus needing three hosts. Alterna- 
 tive stages are exemplified by Hyalomma hebrceum, which is 
 apparently parasitic only in adult condition, while, in the case of 
 Ornithodorus moubata^ the larval stage is passed within the egg- 
 shell, so that the nymph in reality emerges from the egg. 
 
 Among the other insects which have a parasitic interest are 
 the mosquitoes and gad-flies. These are all blood-suckers on 
 man or beast, and play an important part in the conveyance of 
 infection. The various genera of anopheline mosquitoes are the 
 means of transmitting malarial germs from one man to another, 
 while certain adicine mosquitoes are connected with the transmis- 
 sion of certain micro-filaria and also of the germ of yellow fever. 
 
 Of the larger blood-sucking flies, the most important is the 
 Glossina palpalis^ a species of tsetse fly, which transmits the 
 trypanosome of sleeping sickness in Uganda and other parts of 
 Central Africa. Another tsetse fly or Gl. morsitans transmits 
 
372 PARASITES. 
 
 from oxen and horses the infecting trypanosome of ngana cattle 
 disease in South Africa. An allied species of fly, the Stomoxys 
 calcitrans, appears to be associated with the dissemination of the 
 trypanosome of surra among horses in India. In addition to the 
 foregoing, various other large flies are parasitic in their larval 
 stage on man. The more notorious of these are Sarcophaga 
 earnaria,) Ochromyia antJwopophaga, and Bengalia depressa, whose 
 larvae penetrate the skin, produce severe ulcers and other re- 
 pulsive ravages on man in tropical countries. 
 
 Guinea-worm, or the Filaria medinensis, is a formidable 
 parasite, which, in some parts of Africa and India, gives rise to 
 boil-like swellings and sores upon the ankles and legs. There 
 has been much controversy as to how this worm gains entrance 
 into man's system, some maintaining that the entrance is gained 
 through the skin, either by a minute worm passing into a sweat- 
 duct, or by a minute embryo coming in contact with a broken 
 surface of skin ; while others maintain that it always obtains 
 entrance into the body by means of the drinking-water, and then 
 works its way to the superficial parts at which it is generally 
 found. At present this point is not definitely settled, but the 
 opinion is gaining ground that the parasite enters the human 
 body by means of drinking-water. The worm is about y^ inch in 
 diameter, and usually from i to 3 feet long. Like many other 
 animal parasites, its presence in the tissues of man is but a 
 portion of its life-history, and to complete its cycle of exist- 
 ence it requires to pass into the tissues of some other living 
 organism. So far as is known at present, the history of this 
 worm amounts to this. The worm having gained access to man's 
 body in an embryonic state, requires some nine months for its 
 development, and it is only when the stage of maturity is reached 
 and the eggs are about to be hatched that symptoms, in the form 
 of an abscess or boil-like swelling, appear which in any way in- 
 dicate its presence in the human tissues. The embryo which is 
 emitted from man is aquatic in habit, and to further develop 
 needs to pass into water. In this medium it meets with a fresh- 
 water crustacean (cyclops), whose skin it quickly perforates, and 
 in whose body it undergoes a certain degree of larval growth, 
 and afterwards, with its host, the crustacean, reaches the inside 
 of man, most probably by drinking-water. Its subsequent history 
 in man is not known, but the inference is, that it burrows its way 
 to the body surface in time to seek and secure an exit for its 
 embryos into fresh water, in which medium they pass again 
 through the changes already mentioned. This passing through 
 one or more hosts, or individual living organisms, is characteristic 
 of several other animal parasites of man, more particularly of the 
 
FILARIA SANGUINIS HOMINIS. 373 
 
 following, which mainly infest various parts of man's intestines 
 or other viscera. 
 
 Filaria Sanguinis Hominis. — This is a minute hair-like 
 worm, often reaching a length of 3 or 4 inches, found in the 
 blood of men who have lived in certain tropical countries. It is 
 considered to be the young form of another jilaria-like worm, 
 w r hich, in the sexual state, is found in the lymphatics of the 
 subcutaneous connective tissue of persons suffering from two 
 peculiar diseases called chyluria and elephantiasis. The former 
 is marked by periodic attacks, in which the urine becomes milky 
 and, upon standing, coagulates. This condition has been traced 
 to an admixture of urine with lymph, and in which immature 
 nlariae are visible under the microscope. Elephantiasis is attended 
 by an enormous enlargement of the limbs and generative organs. 
 The life-history of the Filaria sanguinis hominis is very curious. 
 The parent worm, or that usually associated with chyluria and 
 elephantiasis, and known as the Fila?'ia Bancrofti^ lies in a 
 lymphatic, and here emits her young into the lymph stream, along 
 which they pass through the thoracic duct into the blood. In the 
 blood, these embryos or young are know r n as the Filaria sanguinis 
 hominis nocturna, in consequence of their exhibiting there an 
 extraordinary periodicity, abounding in the night time, but dis- 
 appearing during the day, when they probably lie at rest in some 
 abdominal or thoracic viscera. This periodicity is for some 
 unknown reason an adaptation to the habits of the mosquito, 
 which is the intermediate host of this parasite. The mosquito, as 
 every one knows, is most active at night, and when it bites the 
 human host, these nlariae curl round its proboscis and are then 
 quickly transferred to its stomach. The greater number of the 
 nlariae so swallowed by the mosquito are digested or destroyed, 
 but a certain few undergo development inside its body, and, when 
 the mosquito retires to some water to lay eggs, or to eventually 
 die, these nlariae which have developed inside its body pass out 
 by boring into the water, whence they get swallowed by man. 
 Once inside the human stomach, the nlariae bore their way into 
 the lymphatics, finally reaching their permanent abode in some 
 distant lymph-vessel, where, as the Filaritz Bancrofti, they give 
 rise to chyluria and elephantiasis, and breed, their progeny passing 
 into the blood as before explained, till, released by the mosquito, 
 they in their turn can complete their cycle of development. Such 
 being the history of this remarkable parasite, it follows that, to 
 prevent people getting affected with it, all water in filaria districts 
 should be boiled and filtered. 
 
 Anchylostoma. — This is a short worm, about \ inch long, 
 which attaches itself, often in large numbers, to the villi of the 
 
374 PARASITES. 
 
 small intestine. It is common in Egypt and some parts of 
 Italy, where, on account of the large amount of blood which it 
 abstracts, it produces a serious and fatal form of anaemia known 
 as anchylostomiasis. The mature eggs of the worm, on being 
 discharged from the patient's intestines, undergo their primary 
 stage of development in wet soil, being much favoured by a high 
 temperature. In the warm damp earth the parasite leads a free 
 existence, and assumes a slightly different shape to that which it 
 presents when in the human bowel ; instead of being rather short 
 and stumpy, it is long and thin. The anchylostoma has only 
 one host, namely man. Recent researches show that the most 
 common mode of entry is through the hair follicles of the skin, 
 though it is possible to convey the larvae to the mouth and food 
 by means of the hands, especially in the case of workers with soil 
 or mud, such as agriculturists, canal workers, and miners. 
 Entering the skin the larvae bore their way to the heart and 
 lungs. Thence they bore their way to the oesophagus attaining 
 their ultimate destination in the intestine. 
 
 It is evident from the life-history of the anchylostoma, that any 
 attempts at prophylaxis are summed up in efforts to prevent the 
 ripe larvae entering the body. This can be secured either by 
 personal hygienic precautions against ingestion of larvae by the 
 mouth and skin infection, or by precluding development of larvae 
 once the eggs leave man's body. Air-borne infection is most 
 improbable ; in mines and agricultural pursuits the most serious 
 risk of infection is by dirty hands and working bare-footed in 
 mud or water. If contamination of the ground by human faeces 
 can be prevented there is no possibility of anchylostomiasis 
 spreading, as ripe larvae then cannot reach those who would 
 otherwise be exposed to infection. As the disease is absent as 
 an endemic affection in any town or community with a moderately 
 good system of excreta removal, the elaboration of some such 
 system is clearly the simplest preventive measure. 
 
 Trichina Spiralis. — This is a small worm, varying from ~ to 
 | inch in length, which attacks not only man, but also pigs and 
 other animals, producing the disease known as trichinosis. In 
 this disease the muscles present a number of ovoid cysts about 
 ^ inch in length, just visible to the naked eye, within which 
 is coiled an immature trichina, not much more than ~ inch long 
 (Fig. 66). If by chance the tissue or muscle containing the 
 capsule be eaten, the capsule is dissolved, and the young worm 
 set free, these rapidly develop, and breed so rapidly that within 
 a week the embryos of the trichina, by burrowing through the 
 walls of the intestine, are able to find their way into all parts of 
 the consumer's body, especially the muscles, in which they soon 
 
TRICHINA SPIRALIS— ASCARIDES. 
 
 375 
 
 get encapsuled, to go through the same history again. When 
 trichinosis occurs in man, it is generally due to the eating of 
 the imperfectly cooked ^^^ 
 
 flesh of pigs suffering from 
 the disease. It is some- 
 what common in Germany, 
 where sausages, hams, and 
 pork are more eaten than in 
 this country. The symp- 
 toms of trichinosis are 
 sickness, prostration, fever, 
 and muscular pains. The 
 mortality is often slight, but 
 occasionally very high. 
 Recent observations show 
 that rats inhabiting abat- 
 toirs suffer largely from 
 trichinosis, contracted by 
 their feeding upon the 
 trimmings and condemned 
 portions of diseased pigs. 
 In view of the well-known 
 tendency of rats to feed 
 upon their own dead, and 
 to frequent styes where pigs are kept, the necessity is great to keep 
 these vermin down and to properly dispose of or destroy all offal 
 and trimmings so that no vermin may reach them. 
 
 Ascarides. — Under this name is included a large family of 
 intestinal parasites. Of those affecting man there are three chief 
 varieties : namely, the lumbricus or round worm, the thread worm, 
 and a tropical kind called Tricoccphalus dispar. The common 
 round worm, or A scar is lumbricoides, is very like an ordinary earth 
 worm ; it is pinkish in colour, tapering at each end, and some 6 
 inches long in the case of the males, and 12 inches in the case 
 of the females. In man, it usually infests the small intestine, 
 where it gives off large numbers of eggs, which are oval, nodu- 
 lated, and about —^ inch in diameter. How and where the eggs 
 develop is not known, but it is supposed to be in some inter- 
 mediate host, possibly an aquatic host ; it is chiefly through water 
 that they appear to reach man. The thread worm, or Oxyuris 
 vermiailaris, is a well-known human parasite, occurring in large 
 numbers in the rectum. The female is about £ inch long, and 
 the male ~ inch. This worm gives off enormous numbers of 
 oval, unsymmetrical eggs, each being ^ inch lon g> an d about 
 half as broad. Improperly cooked or raw vegetables and water 
 
 Fig. 66. — Muscle containing trichinae. 
 
376 PARASITES. 
 
 are the vehicles by which they directly reach man from outside. 
 The Tricocephahis dispar is possibly the most common of all 
 intestinal parasites affecting man in the tropics. Its eggs are 
 voided into the bowel, and when discharged from the bowel the 
 embryo is not differentiated ; its development remains in abey- 
 ance until the egg is carried into water or some damp medium. 
 This happening, development proceeds, and on the egg being 
 swallowed by man in his drinking-water, the embryo is liberated 
 in the alimentary canal, and attaches itself to the mucous mem- 
 brane of the caecum. 
 
 Bilharzia Hsematobia. — This is another worm parasite, about 
 \ inch long, which infests the veins of the large intestine, bladder, 
 and kidney, and gives rise to inflammation of these parts with the 
 passing of blood in the urine. It is prevalent in Egypt, South 
 Africa, and elsewhere. The urine usually contains the ova, or 
 eggs, of the parasite, which are not more than y^- inch in size, 
 having, commonly, a sharp spine at one end. The bilharzia 
 probably gains access to the human body through drinking-water, 
 as we can follow the ova in their escape by way of the urine 
 from the body of the primary host. In water, these ova hatch 
 into minute ciliated embryos, which have been traced into the 
 bodies of certain fresh-water arthropodes, which appear to play 
 the part of intermediate hosts for them, in the same way as 
 certain fresh-water crustaceans do for the embryos of the guinea- 
 worm. If the water be drunk containing these arthropodes, the 
 transference of these embryos of the bilharzia to man is as simple 
 as it is certain. 
 
 Tapeworms. — These are a very common form of parasite in 
 man, both at home and abroad ; their life-histories are also 
 peculiar, as they show that these parasites pass through two 
 distinct phases in two different hosts. One phase of their exist- 
 ence is that in which the head, or scolex as it is called, of the 
 parasite, together with a kind of bladder-like expansion, is 
 embedded in muscle or other solid tissue. The bladder-like 
 expansion or cyst is called a cysticcrcus. If the flesh containing 
 these cysticerci is eaten by any other animal, the scolex or head 
 reaches the intestine of its new host or the consumer, attaches 
 itself to the wall of the intestine, and loses its cyst. Gradually, 
 now from this head grow a series of segments, each of which is 
 square or oblong, and each of which, too, is provided with double 
 sexual organs. The segments are often called proglottides, and 
 the chain or complete series of them may reach a length of many 
 feet, the whole constituting the tapeworm. Each of the segments 
 produces eggs or ova ; these escape into the host's bowels, and are 
 voided by him in his excreta. Some of the ova become attached 
 
TAPEWORMS. 
 
 377 
 
 to grass, or other vegetables, and with them are consumed by an 
 herbivorous animal in whose interior the embryo develops from 
 the egg, and quickly burrows into its host's solid tissues, where 
 it changes into a cysticercus, to go through the same train of 
 changes if devoured by a carnivorous 
 animal. If not so devoured it remains 
 passive, and eventually perishes. 
 
 Man is more subject to the tapeworm 
 than to the cysticercus phase of the 
 parasite's life. One of the most common 
 tapeworms met with in man is the Tce?iia 
 solium, which often grows to a length of 
 7 or more feet. Its head (Fig. 67) is 
 about -£q inch in diameter, and carries 
 four suckers with a double circle of hook- 
 lets surrounding a prominence or rostel- 
 lum. This tapeworm grows to its full 
 size in about four months. The ova are 
 spherical, yt~o mcn m s i ze - The cysti- 
 cercus stage of the Tania solium is called 
 the Cysticercus celluloses, and is most 
 commonly met with in the pig, in which 
 animal it constitutes the affection known 
 
 as "measles," and measly pork is the FiG.6 7 .-Head of 7W* *,//«» 
 chief source of Tcenia solium in man. 
 
 Another tapeworm, somewhat like the preceding, only longer, 
 is that called the Tcenia mediocanellata. It is not uncommon in 
 man. Its head is T V mcn m diameter, resembles that of solium 
 by having four suckers, but differs from it by not having either 
 hooklets or rostellum. The eggs are oval, being about —^ inch 
 in diameter. Its cysticercus is called the Cysticercus bovis, be- 
 cause it occurs in the flesh of cattle ; and the practice of eating 
 underdone or raw beef is the chief source of the media-canellata 
 tapeworm in man. 
 
 A tapeworm which is very common in Russia, Poland, 
 Sweden, and Switzerland is that known as the Bothriocephalus 
 latus. It is a very long tapeworm, often reaching 30 feet 
 in length. Its head (Fig. 68) is ovoid, T ^ inch long, and marked 
 by two longitudinal furrows or suckers, but without hooklets. 
 Its eggs are oval, about 3— inch in size, and fitted with a 
 lid at one end. Its embryo is a ciliated organism found in 
 river- water. Its cysticercus is supposed to be found only in 
 fish, more particularly the pike. 
 
 Man is occasionally affected with a dangerous parasite 
 under the name of hydatid disease. This commonly affects the 
 
378 PARASITES. 
 
 liver, but may occur elsewhere. It is really the cysticercus stage 
 of a tapeworm peculiar to the dog and wolf, and called the 
 
 Tarnia echinococcus. The head of this tape- 
 worm is like that of the Ta?iia solium, only 
 that it is but jj^ inch in width. The tape- 
 worm is short, having, as a rule, but four 
 segments, and the last segment only has 
 reproductive organs. The echinococcus 
 cysticercus in man differs from all other similar 
 cysts, in increasing indefinitely in size and 
 forms, within itself, secondary cysts, some of 
 which again enlarge, and form, by a process 
 Fig. 68.— Head of Bo- of budding, new cysts within themselves. Not 
 inocep atus on ^ ma n, but many animals, are at times 
 
 affected with hydatid disease, in whom the echinococcus cysts are 
 often spoken of as " bladder worms." It is not difficult to under- 
 stand how cattle become infected ; for the proglottides and eggs 
 of the echinococcus tapeworm, voided so constantly, and in such 
 large numbers by the dog, readily find access on to straw, grass, 
 or even water, and with those articles of food and drink are con- 
 sumed by the oxen. In the case of man, possibly the sequence 
 of events is not much different. As with cattle, both proglottides 
 and eggs of the tapeworm from the dog may in many ways be 
 carried in food, especially uncooked vegetables, such as lettuces, 
 or on the hands to the mouth, and thus reach the intestine. Pro- 
 bably, a greater risk of infection lies in the habit which dogs have 
 of licking the hands and faces of their masters, and that often 
 after they have been smelling and snuffing about other dogs. 
 These are considerations which should prevent our too familiar 
 association with dogs, more particularly to avoid their licking us, 
 and frequenting dwelling-rooms or kitchens, to say nothing of 
 keeping them clean, and that their excrement is not allowed to 
 remain about. Moreover, full precautions should be taken to 
 prevent infection of dogs by embryos of echinococcus, as may 
 occur in slaughter-houses, where the so-called bladder worms, or 
 echinococcus cysts from slaughtered and infected animals, are 
 often carelessly thrown down. It is needless to say that dogs 
 eating such echinococcus bladders would soon develop them into 
 sexually mature echinococcus tapeworms. It is with a view to 
 avoiding such possible contingencies as the foregoing that the 
 model bye-laws enact that " No dog may be kept in a slaughter- 
 house ; nor other animal, unless intended for slaughter upon the 
 premises, and then only in proper lairs, and not longer than may 
 be necessary for preparing it for slaughter by fasting, or other- 
 wise." 
 
CLIMATE AND WEATHER. 379 
 
 Although the life-history of these various parasites is but 
 imperfectly known, yet the remarkable facts, of which we have 
 reliable knowledge, distinctly point to the great part which water 
 plays in their diffusion to man, and the importance of avoiding 
 all risks of infection by securing a good and pure water-supply ; 
 at the same time similar precautions are needed to see that all 
 food is properly prepared and cooked before being eaten. . 
 
 CHAPTER X. 
 
 CLIMATE AND WEATHER. 
 
 Our term climate is derived from the Greek word KAtJua, a slope, 
 and probably had its origin in the idea that the diversities of the 
 qualities and conditions of our atmosphere varied according to 
 the bending or sloping of the earth's surface from the equator to 
 the poles. 
 
 The simplest plan of classifying climates is based upon 
 geographical limits, and largely according to latitude. This at 
 best is imperfect unless allowance be made for the influence of 
 warm or cold sea currents, nearness or distance of mountain 
 ranges, and large ocean areas. These latter in particular greatly 
 affect rainfall and exposure to winds. Allowing for these 
 modifying influences, and based upon the principle or limits of 
 latitude, a commonly accepted classification of climates is as 
 follows : — 
 
 Warm Climates. — These include what are called tropical and 
 subtropical climates, marked by high temperature, heavy rainfall, 
 and more or less well-defined dry and wet seasons. Such climates 
 are usually met with in places lying between the equator and 35° 
 of latitude north or south of it. Though possibly all the diseases 
 usually attributed to the influence of warm climates are not rightly 
 so, still they are peculiarly apt to be associated with such affec- 
 tions as heat-stroke, yellow fever, cholera, dengue, liver abscess, 
 dysentery, small-pox, and various forms of malarial fever, while 
 scarlet fever and measles are comparatively rare. 
 
 Temperate Climates. — These have a mean temperature of 
 
380 CLIMATE AND WEATHER. 
 
 6o° F., often with great extremes : four well-defined seasons, 
 usually most rainy during autumn and winter, and the geographical 
 limits of from 35 to 50 of latitude. 
 
 Cold Climates, or those belonging to regions situated between 
 50 of latitude and the poles. In them the summer is short, often 
 lasting but a few weeks, while the winter is long. Snow is exten- 
 sive, but of rain there is little or none. The diseases of temperate 
 climates are mainly those of everyday English life ; while in the 
 cold climates scurvy and scrofula are the principal affections 
 which can be directly attributed to climate. The former arising 
 from a deficient supply of fruit and vegetables, and the latter from 
 the overcrowding and general poorness of living which prevails. 
 Just as diseases of warm or hot climates have an affinity for the 
 abdominal organs, so have the diseases of temperate and cold 
 climates an affinity for the thoracic organs. 
 
 Mountain Climates. — These are peculiar, being marked by 
 extremes of temperature, great clearness and rarefaction of the 
 atmosphere, and lessened atmospheric pressure. Mountain cli- 
 mates are peculiarly favourable to those having imperfect chest 
 development, with hereditary or other tendencies to consumption ; 
 but are unsuitable for those troubled with chronic bronchitis or 
 acute diseases of the lungs, kidney, liver, or brain. The peculiar 
 effects of mountain climates appear to be due to the increased 
 aeration of the blood which takes place during the act of breathing 
 mountain air, and as a result of this, these climates are best suited 
 for those capable of taking abundant exercise, and distinctly 
 hurtful to the aged and very feeble. 
 
 Marine Climates are those prevailing upon islands, capes, and 
 sea coasts, in which the temperature is remarkably equal, rarely 
 reaching extremes, and in which, owing to the increased moisture 
 and rainfall, a certain softness of atmosphere is experienced. The 
 climates of Great Britain, Norway, and Iceland may be taken as 
 types of these so-called marine climates. The principal diseases 
 which appear to be in any way peculiar to marine climates are 
 rheumatism and the various affections of the lungs and air 
 passages, the greater part of which may be due to the dampness 
 and constant weather changes which are so characteristic of these 
 climates. 
 
 The multitudinous effects which climates have upon health 
 have long been recognized, and have constituted one of the most 
 difficult questions which nations and governments have had to 
 consider in regard to schemes of colonization, location of com- 
 munities, and the movement of armies. So great is the influence 
 of climatic conditions upon health, that it is probable that many 
 of the divisions of the human race owe their principal and 
 
TEMPERATURE. 38 1 
 
 essential characters to its continuous action through successive 
 generations. Note the difference between an Englishman and 
 an Italian, or between a German and a native of India. These 
 effects of climate appear really to be the expression or result of 
 the influences of all the various elements or factors and conditions 
 which go together to make a climate. Such are temperature and 
 sunshine, rainfall and moisture, wind and atmospheric pressure or 
 density. The systematic observation and study of these various 
 phenomena constitute the science of meteorology. 
 
 Temperature. — One of the most remarkable facts in connec- 
 tion with man is that when in health he is able to maintain his 
 normal or standard body heat of 98 to 99 F under the most 
 extreme and opposite climatic conditions. This, of course, is 
 not always the case, for at times both extreme cold and heat 
 profoundly affect man's physiological condition. Thus, prolonged 
 exposure to extreme cold causes excessive contraction of the 
 smaller blood-vessels, resulting in so great a shutting off of the 
 blood supply to the extremities that they become gangrenous or 
 frost-bitten. At the same time, if the exposure be very prolonged, 
 the body loses all power of reaction, lassitude sets in, followed 
 by deep sleep, usually ending in insensibility and death. More 
 rarely the languid state is replaced by one of delirium not unlike 
 intoxication. 
 
 Except perhaps in the tropics, the general effect of direct 
 sun's rays on the body is beneficial ; but prolonged exposure to 
 great heat, whether in the sun or in the shade, is accompanied by 
 pronounced physiological disturbance. Some experiments go to 
 show that the body heat itself is increased £0 degree for each 
 degree (Fahrenheit) rise in the air's temperature, while the respira- 
 tions of those living in hot countries, though at first (some six 
 months) increased, are afterwards so much lessened in frequency 
 that the entire respiratory function is reduced by about 18 J per 
 cent. Much of this lessened respiratory function in hot climates 
 is said to be due to the fact that with a high temperature the 
 quantity of oxygen present in the air is diminished. Thus, a 
 cubic foot of dry air at 32 F. weighs 566*85 grs., which, neglect- 
 ing the slight amount of carbon dioxide present, gives in that 
 cubic foot of air 436*5 grs. of nitrogen and 130*35 grs. of oxygen. 
 Assuming that a man at rest breathes 16*6 cubic feet of air pei 
 hour into his lungs, he will at 32 F. receive 2164*2 grs. of 
 oxygen per hour. At a temperature of ioo° F. (which is not 
 unusual in the tropics) a cubic foot of dry air weighs 498 grs., 
 and is made up by weight of 383*5 grs. of nitrogen and 114*5 g rs - 
 of oxygen. Therefore in an hour, breathing as before, the man 
 would receive 1901 grs. of oxygen, or nearly 12 per cent, less 
 
382 CLIMATE AND WEATHER. 
 
 than he would breathe in at the lower temperature. The action of 
 the skin is increased in hot countries by as much as 24 per cent., 
 but the water exhaled by the breath and passed off by the kidneys 
 is proportionately reduced. In hot climates, the general functions 
 of the whole body become impaired, notably the nervous system 
 and digestive organs, which, from being the seat of more or less 
 increased action, are peculiarly liable to become congested and 
 enlarged. The essential requirements for the bearing of great 
 heat by the body is the maintenance of abundant perspiration ; 
 the moment this fails the heat equilibrium is disturbed, and the 
 body heat rises rapidly, accompanied sooner or later by insensi- 
 bility and death from heat-stroke. 
 
 Owing to our senses being insufficiently acute to measure 
 slight changes in temperature, we have to make use, for this 
 purpose, of instruments, called thermometers, which indicate, 
 by means of the expansion or contraction of bodies under heat, 
 its varying degrees of intensity. Liquids are the bodies best 
 suited for this purpose in the construction of thermometers — the 
 expansion of gases being too great, and that of solids too small. 
 Of liquids, mercury and alcohol are practically the only ones 
 used ; the former because it boils only at an extremely high 
 temperature, and freezes at a very low one, and the latter 
 because at atmospheric pressure it does not solidify at the 
 greatest known cold. For these reasons, mercury is used for 
 recording high degrees of heat, and alcohol for low temperatures, 
 the alcohol when so used being generally coloured. Although 
 there are many varieties of thermometers, they can practically be 
 divided into three kinds, namely, the ordinary, the registering, 
 and the recording. 
 
 Ordinary thermometers consist of a capillary glass tube, at 
 the end of which is blown a bulb or reservoir. The manufacture 
 of a thermometer, to ensure accuracy, is one of great delicacy 
 and care ; in the first place, the tube must be divided into parts 
 of equal capacity, or calibrated, as it is called ; next, it must be 
 filled and finally graduated for the construction of the scale. 
 Just as a foot-rule is divided into a number of equal divisions 
 called inches for comparison of length, so is a thermometer 
 marked into a number of parts of equal capacity for the com- 
 parison of temperatures, called degrees. Sometimes the scale is 
 marked upon the thermometer stand, but in the best and more 
 accurate ones it is marked on the actual stem. 
 
 Since ice constantly melts at the same temperature and 
 distilled water under an atmospheric pressure of 29*92 inches, 
 and in a metal vessel always boils at the same temperature, 
 these two temperatures are taken as the limits of the scale, and 
 
TEMPERATURE. 383 
 
 the interval between them is taken as the unit for comparing 
 temperatures, just as a foot or yard are taken for comparing 
 lengths. The melting-point of ice or first fixed limit is usually 
 called zero, and the other fixed limit the boiling-point. On the 
 continent of Europe, the scale of a thermometer is divided into 
 100 parts or so-called Centigrade. This division is really the 
 simplest, and now generally used in this country in connection 
 with all scientific work. In this scale, the zero or freezing-point 
 is at o degrees, while the boiling-point is at 100 degrees. The 
 degrees are usually designated by a small cypher placed a little 
 above on the right of the number, thus 20 , while to indicate 
 temperatures below zero, the minus sign is placed before, thus 
 — io°, or ten degrees below freezing. 
 
 Another scale, known as Reaumur's, is used in Russia and 
 some other parts of the Continent ; in it the fixed points are the 
 same as in the Centigrade : but the interval between them is 
 divided into 80 instead of 100 parts; that is to say, 80 degrees 
 Reaumur equal 100 degrees Centigrade, or 1 degree Re'aumur 
 is I of a degree Centigrade, or 1 degree Centigrade is J of a 
 degree Reaumur. Consequently, to correct Reaumur degrees 
 into Centigrade ones it is necessary to multiply them by |. 
 Similarly, Centigrade degrees are converted into those of Reaumur 
 by multiplying them by f . 
 
 In England and America, for general use, the thermometric 
 scale invented by Fahrenheit is still employed. In this scale 
 the higher fixed point is, like that in the Centigrade and Re'aumur 
 scales, that of boiling water; but the lower fixed point, or zero, 
 is not the temperature of melting ice, but that obtained by 
 mixing equal parts of snow and sal ammoniac, and the interval 
 between the two is divided into 212 parts or degrees. The zero 
 temperature on this scale is lower than that of melting ice, with 
 the result that when a Fahrenheit scale thermometer is placed in 
 melting ice, it stands at 32 degrees, and, therefore, 100 degrees 
 on the Centigrade scale and 80 on the Reaumur equal 212 
 less 32, or 180 degrees on the Fahrenheit, or 1 degree Fahrenheit 
 equals f of a degree Centigrade, and f of a degree Re'aumur 
 For the conversion of any given number of degrees Fahrenheit 
 into Centigrade or Re'aumur degrees, the number 32 must be first 
 subtracted in order that the degrees may count for the same 
 part of the scale, and the result then multiplied by the relative 
 value of the two degrees. Conversely, Centigrade and Reaumur 
 degrees may be converted into Fahrenheit by adding 32 after 
 multiplying by the ratio value. Thus, by the use of the following 
 formulas — 
 
384 CLIMATE AND WEATHER. 
 
 fC. + 3 2 = F. |R.+ 3 2 = F. 
 
 (F. - 32)^ = C. (F. - 3 2)| = R. 
 
 we can show that 20 F. equals — 6°'6 C, or — 5°*4 R., and that 
 20 C. equals 68° F., and 20 R. equals 77 F. 
 
 A good mercury thermometer should answer to the following 
 tests. When completely immersed in melting ice, the top of the 
 mercury should exactly indicate zero or 32 , according as to 
 whether the scale be Centigrade and Re'aumur or Fahrenheit; 
 and when suspended in the steam of water boiling in a metal 
 vessel with the barometer at 29*92 inches, the mercury should be 
 stationary at either ioo° or 212 according to the kind of scale. 
 The value of the degrees should be uniform, as shown by a 
 detached piece of mercury occupying an equal number of degrees 
 in all parts of the tube. 
 
 Owing to the temperature constantly varying, the actual 
 reading observed has but a limited value, so that registering 
 thermometers are required; of these there are two kinds in 
 common use, namely, those known as minimum and maximum 
 thermometers. 
 
 The minimum thermometer or instrument for registering 
 the lowest temperature during a given period of time, is some- 
 times known as Rutherford's minimum. In principle it is very 
 simple, the bulb and part of the stem being filled with coloured 
 alcohol in which a little glass or metal index is placed. When 
 the temperature falls, and the alcohol contracts, the capillary 
 attraction of the liquid draws the index back with it towards the 
 bulb ; but when the temperature rises again, the alcohol passes 
 the index, and leaves the extremity of it farthest from the bulb 
 at the lowest temperature reached. The instrument, after having 
 been read, is readily set up by partially inverting it and letting the 
 index fall to the top of the spirit column ; it is then hung up in 
 a horizontal position. Occasionally air bubbles appear in the 
 alcohol and fix the index, while at other times some of the alcohol 
 volatilizes and condenses at the top of the tube. Both these 
 faults can be easily cured by holding the thermometer bulb 
 downwards and swinging it rapidly round ; this v/ill usually cause 
 the air bubbles to disperse, and displace any condensed alcohol 
 from the top of the tube. If, by chance, as the result of this 
 procedure, the index be thrown into the bulb, a little tapping and 
 patience will bring it out again. 
 
 Of maximum thermometers, or those registering the highest 
 degrees of heat during any given time, there are two in very 
 general use, namely, Negretti's and Phillips's. Both these instru- 
 ments have mercurial columns, a detached portion of which 
 
MAXIMUM AND SIX S THERMOMETERS. 
 
 335 
 
 upi 
 
 serves as an index for the highest temperature reached. In 
 Negretti's, the detachment is made by means of a slight con- 
 traction of the tube, which, while allowing the expanding mercury 
 to pass when the temperature is rising, is suffi- 
 cient to overcome the natural cohesion of the 
 metal, when contracting, to prevent it drawing 
 it back on cooling. In Phillips's, the detached 
 portion of the mercurial column is separated 
 from the rest by a bubble of air. Both these 
 instruments are placed horizontally, and both 
 can be re-set by lowering the bulb, and then 
 either gently tapping or swinging the thermo- 
 meter. 
 
 Previous to the invention of these minimum 
 and maximum thermometers, a registering in- 
 strument known as Six's thermometer (Fig. 69), 
 from the name of its inventor, was much used, 
 and is so now. The tube of the instrument is 
 long and U-shaped. One limb constitutes the 
 cold tube, and has at its extremity a bulb, 
 while the other limb is the heat tube, having 
 at its top or end a small chamber in which is 
 confined some air. The middle portion of the 
 tube contains mercury extending round the 
 bend and part of the way up each limb. The 
 bulb and both tubes or limbs above the mercury 
 contain alcohol. Inside the alcohol are tw r o 
 steel indices, one being in the cold tube and 
 the other in the heat tube. These are readily 
 set, or caused to rest gently upon either column 
 of mercury by moving them by means of a 
 magnet. This being done, if the temperature 
 rise, the alcohol in the bulb will expand and 
 push down the mercury in the cold leg, but raise that in 
 the heat leg, and by so doing drive up the index in it until 
 the temperature ceases to rise, when the point of maximum 
 heat will be indicated by the lower end of that index. On a 
 fall of temperature precisely the reverse will happen, for then the 
 spirit within the bulb will contract, and the pressure in the air 
 chamber at the top of the heat leg will force the mercury down 
 in it, but up in the cold limb, while the cold index will continue 
 to go up so long as the temperature continues to fall. Of course 
 the scales read downwards on the cold leg and upwards in the 
 heat one, and in each the lower end of the index shows respec- 
 tively the lowest and highest temperature reached since the 
 
 o 
 
 Fig. 69.— Six's ther- 
 mometer. 
 
386 CLIMATE AND WEATHER. 
 
 instrument was last set. The presence of the air chamber makes 
 a Six's thermometer unsuited for travelling, and necessitates the 
 vertical position. 
 
 Of recording thermometers, the cheapest are those of Cripps 
 or Richard. The bulb is a large curved flattened tube, filled 
 with a liquid which tends to straighten with an increase of heat, 
 and this being connected with a long lever in such a manner as 
 to rise with increase of temperature and to fall with decrease, 
 marks a tracing line upon a revolving cylinder. This cylinder 
 depends upon a clockwork arrangement, and can be wound up, 
 started, and left untouched for given periods of time, at the end of 
 which records of temperature will be found for every instant during 
 the period. As the curvature of the tube and the spring mechanism 
 are apt to alter, these instruments need to be corrected and 
 compared periodically with an accurate mercurial thermometer. 
 
 In all efforts to compare climates or temperatures, it is not 
 only necessary to have accurate thermometers, but also to place 
 them so far as possible under similar conditions ; for this purpose 
 uniformity of exposure is obtained by placing or exposing ther- 
 mometers in certain standard screens. The thermometers already 
 described are invariably kept in the shade, and carefully protected 
 from all direct rays of the sun and effects of reflected or radiated 
 heat from walls and buildings. Owing to this fact, these instru- 
 ments are sometimes spoken of as shade thermometers in contra- 
 distinction to others which will be described later on, and known 
 as sun thermometers. The screen or arrangement for shade 
 thermometers is a hut or box known as Stevenson's screen. It is 
 made of stout boards, with a ridge roof and louvred sides open 
 below, and standing some 4 feet off the ground on four legs. It 
 is placed where it will be freely exposed to the movements of the 
 air, and at least 20 feet away from any house or building. All 
 thermometers should be read once daily, say 9 a.m., when the 
 highest and the lowest temperatures of the previous twenty-four 
 hours will be recorded. 
 
 The mean temperature of the day may be obtained by taking 
 a single reading at 9 p.m., or by taking the mean of two readings 
 at 9 a.m. and 9 p.m., or by taking the mean of the maximum and 
 minimum recorded temperatures ; this is usually correct for 
 winter, but in summer may be as much as 2 too high. 
 
 The only true mean can be obtained by taking a mean of 
 hourly readings. The weekly, monthly, and annual means are' 
 derived from daily means. As a rule, the lowest temperature is 
 recorded at 3 a.m. and the highest at 2 p.m., but of course proximity 
 to the sea or elevation and influence of latitude considerably affect 
 these observations. 
 
SOLAR RADIATION THERMOMETERS. ^7 
 
 Some idea of the intensity of the sun's heat is obtained by 
 means of what are called solar radiation thermometers or maximum 
 thermometers placed direct in the sun's rays. In order to avoid 
 loss of heat by reflection from the bright glass surface of the bulb, 
 this and one inch of the stem is coated with lamp-black, and this 
 again, to protect it from being washed off by rain, is placed in a 
 glass case out of which air has been pumped to make it a vacuum. 
 Unfortunately, the presence of the outer glass covering largely 
 interferes with the cooling influence of wind, which materially 
 affects the distribution of heat by the sun in Nature. Notwith- 
 standing this theoretical defect, the blackened bulb maximum 
 thermometer in vacuo is the best instrument we have for measuring 
 the amount of heat given out or radiated by the sun. The 
 instrument is exposed freely to the sun and air by fixing it 
 horizontally 4 feet above the ground, well away from trees or 
 walls, and with its bulb, in this country, pointing south-east. The 
 heat recorded by such an instrument will be the temperature at 
 which an equilibrium or balance is established between the heat 
 produced by the direct rays of the sun on the bulb, and the cool- 
 ing caused by radiation or loss of heat from the bulb to the glass 
 jacket or covering ; this latter, of course, will have practically the 
 same temperature as that of the air. It follows, therefore, that 
 the excess of the temperature of the black bulb over that of the 
 outer air, as registered by the maximum shade thermometer, will 
 be an approximate measure of the power of the actual sun's rays, 
 or, in other words, the power of the sun's radiation of heat. This 
 is but a crude measure of the actual heat emitted by or derived 
 from the sun's rays. The only accurate method is by a special 
 instrument called a " bolometer." In principle the bolometer 
 is simple : it depends on the fact that the electrical resistance of 
 a metal is increased by heat. Two strips of metal are connected 
 wdth a galvanometer and one of them is exposed to the sun's rays 
 passing through a narrow slit. When heated by the sun's rays, 
 the resistance of this piece of metal is increased and the galvano- 
 meter needle moves. So sensitive is this instrument that 
 differences of temperature of less than one hundred millionth of 
 a degree can be detected. After allowing for atmospheric 
 absorption it is estimated that the solar constant is 30 calories, or 
 the earth receives hourly enough heat to melt a circular disc of 
 ice nine-tenths of an inch thick and nearly 8000 miles in diameter. 
 In a year, the solar rays would melt a disc 657 feet thick. 
 Owing to varying atmospheric conditions the amount of solar 
 heat varies at different points on the earth's surface. 
 
 Not only is there a constant gain of heat by the earth from 
 the sun, but there is also a more or less constant loss of heat 
 
3 88 
 
 CLIMATE AND WEATHER. 
 
 from the earth and from all objects on it. This loss of heat is 
 spoken of as terrestrial radiation, and is very much greater when 
 the sky is clear and the air dry than when overcast with clouds, 
 or when much moisture is present in the atmosphere. It is 
 owing to the comparative rapidity with which soil covered with 
 grass and vegetation radiates heat into space that the air over 
 grass-plots and lawns is colder than that in immediate contact with 
 or over bare flower-beds and gravel-walks. This loss of heat from 
 
 Fig. 70.— Minimum thermometer on grass for recording terrestrial radiation. 
 
 the earth is most marked where the disturbing influence of air 
 currents is least, hence it is usual to place a thermometer intended 
 to measure radiation upon the ground. The amount of the loss 
 of heat by radiation is determined by placing a minimum thermo- 
 meter, as already described, on short supports some 4 inches 
 off the ground on a plot of grass (Fig. 70). The difference or 
 defect of this minimum temperature below that of the air 
 minimum in the shade is taken as the amount of terrestrial 
 radiation. 
 
 Sunshine. — The duration of the sunshine is a very important 
 factor in all climates, and the extent of this duration is recorded 
 by either what is called Whipple-Casella's apparatus or by 
 Jordan's. The former is mainly a glass sphere so mounted 
 that when the sun shines its rays are focussed as by a lens upon 
 a strip of cardboard, with the result that a burnt track or hole 
 is left for such periods of time as the sun shines. The cardboard 
 is so placed in the instrument that definite sections of it corre- 
 spond to periods of time and hours. Jordan's instrument is, 
 strictly speaking, rather a recorder of sunlight than of sunshine. 
 It consists of a circular box in which some sensitive photographic 
 paper is placed, and the sunlight entering through a slit leaves a 
 varying record of its duration and intensity. The paper can be 
 readily " fixed " by washing in clean salt water. 
 
 Rainfall. — No factors have more influence upon the suitability 
 or unsuitability of the climate of any particular country than the 
 amounts of its humidity and rainfall. The p hys ica I cause of rain 
 
RAINFALL. 
 
 339 
 
 is the sudden chilling of comparatively warm air, more or less 
 laden with moisture," either by its ascent into the upper and 
 colder regions of the atmosphere, or by its impact against cold 
 mountain slopes, or with the colder surface of the ground. The 
 former cause is more potent in the summer, the latter in winter. 
 It was formerly supposed that rain was largely caused by the 
 mixture of masses of air of different temperatures. But, even 
 supposing that any such admixture did take place, a comparison 
 between the units of heat set free by condensation and the 
 weight of aqueous vapour per cubic foot of air at any two given 
 temperatures — one high, the other low — shows that the mixture 
 of volumes of air cannot be very effective in causing precipita- 
 tion (Hann). In fact, the latent heat set free in the process of 
 condensation largely prevents that fall of temperature which is 
 assumed to take place and to cause a rainfall. 
 
 The amount of rainfall is measured by an instrument called 
 a rain-gauge, which, in its simplest form, is a copper funnel 
 leading: to a can or other 
 
 receiving vessel (Fig. 71). 
 In this country the funnel is 
 usually circular and 8 inches 
 in diameter, so that its area 
 in square inches is accurately 
 known. Having entered the 
 funnel, the rain passes down 
 a long and narrow tube, 
 which at its end is curled 
 upward to check evaporation, 
 into a metal-collecting vessel. 
 The rain, having been col- 
 lected in the receiver, is mea- 
 sured in a graduated glass 
 vessel, the divisions of which 
 correspond to half-inches and 
 tenths. The measuring vessel 
 
 Fig. 71. — Rain-gauge and measuring-glass. 
 
 is divided proportionately to the area of the gauge, the diameter 
 of which should always be some simple unit, like 5 or 8 inches, 
 so that if the original measure get broken, a new one can be 
 readily improvised and graduated. Thus, take an 8-inch gauge, 
 the diameter being 8 inches, its receiving area is 50*26 square 
 inches ; therefore, 1 inch of rainfall, or rain 1 inch deep over a 
 town, would deposit in that particular rain-gauge 50*26 cubic 
 inches of water, or 29 J fluid ozs. Therefore, if 145 fluid ozs. of 
 water be poured into the proposed measuring glass, and the 
 vessel be marked with a line at its level, that line will represent 
 
39° 
 
 CLIMATE AND WEATHER. 
 
 the graduation of J inch of rain; subdivision markings are 
 similarly made for tenths and hundredths of an inch. 
 
 In the absence of a properly constructed rain-gauge, the 
 amount of rainfall can be readily measured in any receiving 
 vessel, provided its receiving area is known, by measuring the 
 volume collected in either fluid ounces or cubic centimetres, and 
 making the calculation on the basis of the facts that i fluid 
 oz. equals 1728 cubic inch, and that 1 c.c. is 0*061 cubic inch. 
 Thus- 
 cubic centimetres of rain collected X 0*061 . 
 — 7-. : — r inches of rain, 
 
 area of receiving vessel in square inches 
 
 fluid ounces of rain collected X 1728 . 
 
 or —.r- . . —j-. • — t — = inches of rain. 
 
 ' area of receiving vessel in square inches 
 
 More rain is collected on the ground than on the top of a 
 building, or on a stand at a height above the ground. For this 
 reason the best place for a rain-gauge is on the ground in a 
 well-exposed position, with the rim about one foot above the 
 earth. A rain-gauge should never be placed upon a house-roof, 
 unless, as in towns, no sufficiently open space is available. The 
 spot on which a rain-gauge is exposed should be clear of all 
 objects whose height is greater than their distance from the 
 gauge. Rain should not be collected in the measuring glass, as it 
 is liable to break, especially during frosts. Snow or hail can be 
 measured by thawing the quantity collected and measuring the 
 water which results. To avoid snow being blown out of the 
 gauge, the upper edge of the funnel is usually fitted with a 
 vertical rim about 6 inches in depth, and ground to a fine edge 
 on the top. 
 
 The amount of rain which falls varies, of course, very much 
 with the place ; but in determining the average fall at any station, 
 it is necessary to deal with observations extending over long 
 periods. In England and Wales, the average rainfall each year 
 is 3376 inches; in Scotland, 46*56 inches; in Ireland, 38*54 
 inches. The average annual rainfall for the United Kingdom is 
 37*30 inches; for Great Britain, 36*69 inches. On the east coast 
 of England not much more than 20 inches of rain falls in a year, 
 while on the west coasts of both Scotland and Ireland it averages 
 as much as 60 or 80 inches; in some parts of Cumberland as 
 much as 150 inches a-year have been known to fall. It is very 
 rarely that more than 1 inch of rain falls anywhere in Great 
 Britain in one day ; though occasionally as much as 5 inches have 
 been known to fall. For furnishing meteorological returns, a 
 minimum record of o'oi inch is considered as characteristic of 
 a rainy day in this country. 
 
HUMIDITY. 391 
 
 Humidity. — The question of the amount of moisture in the 
 air is somewhat complicated, and is usually spoken of as the 
 degree of humidity. It was explained in an earlier chapter that 
 water is constantly evaporating into the air, and that the amount 
 of water or moisture which the air can hold or retain is con- 
 stantly varying with its temperature. Thus at 32 F. a cubic 
 foot of dry air can only take up 2*10 grs. of water, while at 
 ioo° F. it can take up as much as 19*84 grs. When air is so 
 full of moisture that it can contain no more, it is said to be 
 saturated. In this country the air upon an average contains 
 about three-fourths of the amount of water needed to saturate it 
 — that is, it has an humidity of about 75 per cent. ; but if the air 
 containing this amount of moisture be cooled down, it will reach 
 a degree of heat at which that same amount of moisture will 
 suffice to saturate it, and if cooled still more, it will reach a 
 temperature insufficient to retain that moisture, with the result 
 that it must part with some of it, the amount so parted with 
 being precipitated or deposited as rain, snow, mist, or dew. For 
 instance, 100 cubic feet of air three parts saturated with moisture 
 at a temperature of 70 F. would hold 600 grs. of water; if for 
 some cause or other the temperature of that 100 cubic feet of air 
 were reduced to 6i° F., that volume of air would become quite 
 saturated, because at that temperature it could only hold 600 grs. ; 
 and if the temperature were still further reduced, say to 5 6° F., 
 it could only retain 500 grs. of moisture; therefore the difference 
 between 600 and 500 grs., or 100 grs. of water, would be released 
 or deposited as mist, dew, or rain. 
 
 It has been pointed out by some observers that occasionally, 
 in perfectly pure air, a pressure of vapour may be maintained 
 greater than that corresponding to the temperature of saturation 
 (Aitken). In fact, that condensation will not in general begin 
 unless some nucleus is present to which the particles of water 
 can attach themselves. It is on the presence of solid particles 
 of dust in the air that the formation of mists and fogs depends, 
 the precise degree of mist or fog depending on the amount 
 of dust present, and on the size and constitution of the particles. 
 When the number of dust particles is large or their size consider- 
 able, and the quantity of vapour condensed is small, we get the 
 phenomenon of a town, or so-called dry fog. The condensation 
 of water upon invisible particles so increases their size as to make 
 them visible. Often in the case of town fogs their obviousness 
 is not so much due to the action of the moisture condensed on 
 the particles as to the excessive size and quantity of the particles 
 themselves. What are known as sea fogs probably occur in 
 air which is comparatively dry, because the dust in their case 
 
39 2 
 
 CLIMATE AND WEATHER. 
 
 consists largely of salt grains derived from spray or surf, and 
 which have a great affinity for moisture. If the quantity of 
 condensed moisture is large, or the amount of dust and other 
 solid nuclei small, we get what is called a mist, and it is merely 
 a question of the degree of the moisture present which determines 
 where the mist ends and actual rain begins. 
 
 The formation of dew is precisely analogous ; in this case 
 the solid substance on which the moisture is precipitated or 
 condensed is the surface of the ground, or a blade of grass, and 
 not solid nuclei like soot or dust floating about in the air, as in 
 the formation of fogs. Owing to the rapidity with which the 
 earth, under certain circumstances, loses heat by radiation, as, 
 for instance, on a fine clear night, the strata of air containing 
 
 Fig. 72.— Dine's hygrometer. 
 
 moisture which are in contact with the cooling earth, themselves 
 become reduced so much in temperature that they are no longer 
 able to retain their water vapour, but actually lose it by con- 
 densation upon the ground, where it constitutes what we call dew. 
 The particular temperature at which air saturated or loaded with 
 moisture deposits its water is called the dew-point. It is from 
 the determination of this dew-point that the weight of water 
 present in the air (or, in other words, the percentage of saturation 
 of the air for the existing temperature) is calculated. This, of 
 course, expresses the degree of humidity. 
 
 For the determination of the temperature of the dew-point, 
 certain instruments called hygrometers are used. Of these there 
 have been many varieties. A very ingenious instrument of this 
 kind is that known as Dine's hygrometer (Fig. 72). Some cold 
 
HYGROMETERS. 
 
 393 
 
 water is put into the cup A, and allowed to flow through the 
 channel D, whence it rises through a perforated diaphragm into 
 a space above, in which rests the bulb of a thermometer; the 
 space itself being rendered water-tight by a thin cover of blackened 
 glass, E. On turning the tap B, the water flows through the 
 chamber, and so cools the glass cover down until a thin him of 
 dew or moisture is deposited on it from the contiguous air ; the 
 precise temperature of this dew-point, or moment of dew, being 
 deposited on the black glass is read off on the thermometer C, 
 and recorded as that of the dew-point. 
 
 Another instrument, known as Daniel's hygrometer (Fig. 73), 
 consists of a bent tube with a globe at each end, and is partly 
 
 Fig. 73. — Daniel's hygrometer. 
 
 filled with ether, the rest of the space in the tube being filled with 
 the ether vapour, all the air having been expelled. One globe is 
 made of blackened glass, and contains a thermometer, while the 
 other is covered with muslin. Before using the instrument, the 
 ether is made to pass into the blackened globe containing the 
 thermometer, while the muslin surrounding the second globe is 
 moistened with ether. This ether rapidly evaporates, causing a 
 condensation of some of the ether vapour inside the tube ; this in 
 its turn produces an evaporation of the ether in the blackened 
 bulb. Now, whenever evaporation occurs, there is absorption of 
 heat, so that the black bulb gradually becomes colder and colder, 
 and the moment is soon reached when the air in contact with it 
 begins to deposit dew on its surface. So soon as this happens, 
 the temperature shown by the contained thermometer is read off 
 and recorded as the dew-point. 
 
394 
 
 CLIMATE AND WEATHER. 
 
 The most common form of hygrometer now employed in 
 this country is that known as the dry-and-wet bulb thermometer 
 
 (Fig. 74). It really consists of two 
 ordinary thermometers mounted on 
 a frame side by side. One of these 
 has its bulb covered with muslin, 
 and kept constantly moist by being 
 connected with a small vessel con- 
 taining distilled water, by means 
 of the capillary action of a piece 
 of cotton wick, which has been pre- 
 viously well freed from grease by 
 being boiled in ether. The dry 
 bulb gives, of course, the tempera- 
 ture of the air, while the wet one, 
 in consequence of the evaporation 
 constantly going on from its sur- 
 face, gives a lower reading. The 
 difference between the two tem- 
 peratures recorded indicates the 
 vapidity with which evaporation is 
 proceeding, and, moreover, since 
 evaporation is faster the drier the 
 air, the indication of the degree of 
 evaporation is a measure of the 
 dryness or moistness (otherwise 
 humidity of the air). If the air be 
 saturated with moisture, of course 
 no evaporation is going on, and 
 the two thermometers will record 
 the same temperature. In frosty 
 weather, frequently the muslin 
 covering and the water in the vessel will freeze, with the result 
 that evaporation will not take place. In such case it suirices to 
 brush the frozen muslin over with a brush dipped in cold water 
 and allow this to freeze ; at such time evaporation will be going 
 on from the ice surface, so that it will be equivalent to its having 
 a damp but unfrozen bulb. 
 
 The calculation of the dew-point from the readings of the dry 
 and wet bulbs can be roughly made by taking it to be as much 
 below the wet-bulb reading as that is itself below the dry ; but 
 for greater accuracy use must be made of certain factors which 
 have been worked out by Glaisher, and given in the following 
 table : — 
 
 Fig- 74.— Mason's hygrometer, or the 
 dry-and-wet-bulb thermometer. 
 
ESTIMATION OF THE DEW-POINT, 
 
 395 
 
 Reading of 
 
 the dry-bulb 
 
 therm. 
 
 
 Reading of 
 
 
 Reading of 
 
 
 Reading of 
 
 
 Factor. 
 
 the dry-bulb 
 therm. 
 
 Factor. 
 
 the dry-bulb 
 thenn. 
 
 Factor. 
 
 the dry-bulb 
 therm. 
 
 Factor. 
 
 F. 
 
 
 F. 
 
 
 F. 
 
 
 F. 
 
 
 IO° 
 
 s- 7 s 
 
 33° 
 
 3'oi 
 
 56° 
 
 I -94 
 
 79° 
 
 I '6 9 
 
 11° 
 
 878 
 
 34° 
 
 277 
 
 57° 
 
 1*92 
 
 8o° 
 
 r68 
 
 12° 
 
 878 
 
 35° 
 
 2'6o 
 
 58° 
 
 i'9o 
 
 8i° 
 
 i-68 
 
 13° 
 
 877 
 
 36° 
 
 2-50 
 
 59° 
 
 1-89 
 
 8 2° 
 
 1-67 
 
 14° 
 
 876 
 
 37° 
 
 2-42 
 
 6o° 
 
 i-88 
 
 83 
 
 ■1-67 
 
 15° 
 
 875 
 
 38 
 
 2-36 
 
 6i° 
 
 1*87 
 
 84 
 
 r66 
 
 1 6° 
 
 870 
 
 39° 
 
 2-32 
 
 62 
 
 r86 
 
 85 
 
 I-6 5 
 
 i 7 ° 
 
 8-62 
 
 40 
 
 2-29 
 
 63 
 
 1-85 
 
 86° 
 
 1-65 
 
 i8° 
 
 8-50 
 
 41° 
 
 2-26 
 
 6 4 ° 
 
 1-83 
 
 87 
 
 1-64 
 
 19 
 
 8*34 
 
 42° 
 
 - *o 
 
 65 . 
 
 1-82 
 
 88° 
 
 1 -64 
 
 20° 
 
 8-14 
 
 43° 
 
 2*20 
 
 66° 
 
 r8i 
 
 89 
 
 1-63 
 
 21° 
 
 7-88 
 
 44° 
 
 2-18 
 
 67 
 
 1 -So 
 
 90 
 
 1 -63 
 
 22° 
 
 7-60 
 
 45° 
 
 2"l6 
 
 68° 
 
 179 
 
 9i° 
 
 1-62 
 
 23° 
 
 7-28 
 
 46° 
 
 2"I4 
 
 69 
 
 178 
 
 92 
 
 1*62 
 
 2 4 ° 
 
 6*92 
 
 47° 
 
 2*12 
 
 70 
 
 177 
 
 93° 
 
 i-6i 
 
 2 5 ° 
 
 6-53 
 
 4S 
 
 2TO 
 
 7i° 
 
 176 
 
 94° 
 
 1 '60 
 
 26° 
 
 6-o8 
 
 49° 
 
 2-08 
 
 72 
 
 175 
 
 95° 
 
 i - 6o 
 
 27 
 
 5*6i 
 
 5o° 
 
 2*o6 
 
 hiO 
 /d 
 
 174 
 
 96 
 
 1 '59 
 
 28° 
 
 5-12 
 
 5i° 
 
 2*04 
 
 74° 
 
 173 
 
 97° 
 
 i'59 
 
 29 
 
 463 
 
 52° 
 
 2'02 
 
 75° 
 
 172 
 
 98 
 
 r 5 8 
 
 3 o° 
 
 4'i5 
 
 53° 
 
 2*00 
 
 76 
 
 171 
 
 99° 
 
 r 5 8 
 
 3i° 
 
 3 '60 
 
 54° 
 
 1-98 
 
 77° 
 
 170 
 
 IOO° 
 
 i'57 
 
 
 332 
 
 55° 
 
 I'96 
 
 78 
 
 1*69 
 
 
 
 To use the table, the rule is to multiply the difference be- 
 tween the readings of the two bulbs by the factor corresponding 
 to the reading of the dry bulb, and subtract the product from the 
 dry bulb ; the result is the temperature of the dew-point. Thus, 
 say the dry bulb is 62 , and the wet bulb is 5 6°; their difference 
 is 6, and this, multiplied by the factor i'86, or that corresponding 
 to the dry-bulb reading, gives iri6, and this, taken from 62 , 
 yields 5o°*84 as the temperature of the dew-point. 
 
 Having obtained the temperature of the dew-point, the 
 relative humidity is determined by further reference to a table, 
 like the following, in which the weight of a cubic foot of vapour 
 constituting saturation, at various temperatures is given ;— 
 
396 
 
 CLIMATE AND WEATHER. 
 
 
 Weight in 
 
 
 Weight in 
 
 
 Weight in 
 
 
 Weight in 
 
 Temp. 
 
 grains of a 
 
 Temp. 
 
 grains of a 
 
 Temp, 
 
 grains of a 
 
 Temp. 
 
 grains of a 
 
 F. 
 
 cubic foot of 
 
 F. 
 
 cubic foot of 
 
 F. 
 
 cubic foot of 
 
 F. 
 
 cubic foot of 
 
 
 vapour. 
 
 
 vapour. 
 
 
 vapour. 
 
 
 vapour. 
 
 o° 
 
 o'55 
 
 26° 
 
 r68 
 
 5i° 
 
 4-24 
 
 76 
 
 9-69 
 
 1° 
 
 o'57 
 
 27 
 
 1*75 
 
 52° 
 
 4*39 
 
 77° 
 
 9'99 
 
 2° 
 
 o'59 
 
 28 
 
 1-82 
 
 53° 
 
 4*55 
 
 78° 
 
 10-31 
 
 3° 
 
 0*62 
 
 29 
 
 1-89 
 
 54° 
 
 47* 
 
 79° 
 
 10-64 
 
 4° 
 
 0-65 
 
 30 
 
 1-97 
 
 55° 
 
 4-87 
 
 8o° 
 
 10-98 
 
 5° 
 
 o-68 
 
 3i° 
 
 2-05 
 
 56 
 
 5*o4 
 
 8i° 
 
 11-32 
 
 6° 
 
 071 
 
 32° 
 
 2-13 
 
 57° 
 
 5'2i 
 
 82 
 
 11-67 
 
 7° 
 
 074 
 
 33° 
 
 2*21 
 
 58 
 
 5*39 
 
 83 
 
 12-03 
 
 8° 
 
 077 
 
 34° 
 
 230 
 
 59° 
 
 5-58 
 
 84 
 
 12-40 
 
 9° 
 
 o-So 
 
 35° 
 
 2-39 
 
 6o° 
 
 577 
 
 85 
 
 12-78 
 
 IO° 
 
 0-84 
 
 36 
 
 2-48 
 
 6i° 
 
 5 '97 
 
 86° 
 
 *3'"7 
 
 n° 
 
 o-88 
 
 37° 
 
 2'57 
 
 62° 
 
 6*17 
 
 87 
 
 i3'57 
 
 12° 
 
 0*92 
 
 38 
 
 2-66 
 
 63° 
 
 6*38 
 
 88° 
 
 13-98 
 
 13° 
 
 0-96 
 
 39° 
 
 276 
 
 64 
 
 6-59 
 
 89 
 
 14-41 
 
 4° 
 
 I'OO 
 
 40° 
 
 2-86 
 
 6 A°o 
 
 6-8i 
 
 90 
 
 14*85 
 
 i5° 
 
 I "04 
 
 4i° 
 
 2-97 
 
 66° 
 
 7-04 
 
 91 
 
 15-29 
 
 1 6° 
 
 1*09 
 
 42 
 
 3-o8 
 
 67 
 
 7-27 
 
 92 
 
 1574 
 
 i 7 ° 
 
 114 
 
 43° 
 
 3'20 
 
 68° 
 
 7-5* 
 
 93° 
 
 l6'2I 
 
 1 8° 
 
 1-19 
 
 44° 
 
 3'32 
 
 69 
 
 776 
 
 94° 
 
 16-69 
 
 19° 
 
 1 '24 
 
 45° 
 
 3 "44 
 
 7o° 
 
 8-oi 
 
 95° 
 
 17-18 
 
 20° 
 
 1-30 
 
 46° 
 
 3'5 6 
 
 7i° 
 
 8-27 
 
 96 
 
 17-68 
 
 21° 
 
 1-36 
 
 47° 
 
 3'69 
 
 72 
 
 8-54 
 
 97° 
 
 18-20 
 
 22° 
 
 1 '42 
 
 48 
 
 3-82 
 
 73° 
 
 8-82 
 
 98 
 
 18-73 
 
 2 3 ° 
 
 1-48 
 
 49° 
 
 3*96 
 
 74° 
 
 910 
 
 99° 
 
 19-28 
 
 24° 
 
 i'54 
 
 50° 
 
 410 
 
 75° 
 
 9'39 
 
 IOO° 
 
 1984 
 
 25° 
 
 i'6i 
 
 
 
 
 
 
 
 It is usual to express saturation by 100, and to calculate the 
 relative humidity or the ratio of the absolute humidity to satura- 
 tion by dividing the weight of a cubic foot of vapour correspond- 
 ing to the temperature of the dew-point by that corresponding to 
 the temperature of the air, and multiplying by 100. Thus, taking 
 the same example as given above, in which the dry bulb reads 
 6 2 , the wet 5 6°, and the dew-point is found to be 5o°'84, and using 
 the foregoing table, we get the weight of moist vapour per cubic 
 foot corresponding to the dew-point to be 4*21 grs., and this 
 divided by 6*17, or the corresponding vapour weight for the air 
 temperature, gives o*68, and that multiplied by 100 shows the 
 relative or percentage humidity to be 68. 
 
 This percentage saturation of the air is practically an inverse 
 measure of the drying power of the air, and as such has a most 
 important bearing upon climatic conditions, more particularly the 
 degree of radiation from the earth's surface. We are all familiar 
 with the peculiarly unpleasant effects of a hot moist atmosphere, 
 
EVAPORATION— WINDS. 397 
 
 and with the invigorating influence of dry and crisp air. A 
 saturated atmosphere at from 35 to 50 F. will be found to be 
 intolerably chilly, and although the evaporation may be checked, 
 and this source of heat-loss removed, yet the conduction and 
 radiation due to the vapour in the air will be enormous. A 
 temperature of 50 to 65 F. in a nearly saturated atmosphere 
 seems to be not uncomfortable, as under those conditions an 
 equilibrium seems to be established between the cooling action 
 by conduction and radiation, due to the vapour in the air, and the 
 supply of heat from checked skin evaporation. A saturated atmo- 
 sphere with a temperature of from 65 to 8o° F. becomes oppressive 
 and sultry. Above 8o° F., a saturated air becomes most oppressive, 
 and it is doubtful whether life could be long sustained in a saturated 
 atmosphere of 90 to ioo° F., as the surplus heat cannot be re- 
 moved by conduction or radiation, while at the same time the natural 
 effort of the system to produce evaporation is enormously exagge- 
 rated. Humidity of the air is very generally supposed to be 
 associated with the spread, or rather prevalence of disease ; much 
 moisture in the air certainly favours the continuance of colds, but 
 at the same time appears to relieve bronchitis by assisting expecto- 
 ration and the general discharge of mucus. Malarial diseases are 
 said never to attain their worst form except the air be saturated 
 with moisture, but on this point the evidence is not very strong. 
 
 Evaporation. — How much water is returned to the atmosphere 
 by evaporation from any moist surface, such as that of the earth, 
 is a factor which largely affects climate, but our knowledge regard- 
 ing it is small, as it is both complicated and regulated by the 
 temperature, and the degree of moisture in the air and winds. In 
 this country, the mean annual evaporation from a square inch of 
 water surface has been calculated to be about 20 inches. Various 
 attempts have been made from time to time to measure the 
 evaporation going on. An approximate idea of its amount can 
 be obtained by exposing a measured volume of water in an open 
 vessel of known area, and deducting from its final volume, after 
 exposure for a given period, the amount of rain which has been 
 known to fall into it during that time. 
 
 Winds. — The facts relating to winds are practically limited to 
 those connected with direction, force or pressure, and velocity. 
 As a rule, there is comparatively little trouble in obtaining records 
 as to direction, as, if no vane is convenient, the smoke from a 
 chimney will readily give the information, provided, of course, the 
 observer has a precise idea as to where lies his north or south. 
 A wind vane should be placed perfectly clear of trees, buildings, or 
 anything likely to deflect the course of the wind, and, too, should 
 be kept clean, and oiled to avoid sticking. All wind observations 
 
3 gS climate and weather. 
 
 should be recorded to the nearest point of the compass. To 
 calculate the mean direction, it is usual to give an arbitrary numeri- 
 cal value to each observation, and then to analyze them. Thus, 
 suppose we read to 16 points of the compass, and give a numeri- 
 cal value of 4 to each observation ; if the wind be due N., we 
 should give to N. the full value of 4 ; if the reading were N.YV , 
 we should give half the value of the observation, or 2, to N., and 
 the other half to W. If the reading were N.N.W., then N. would 
 get 3, and W. get 1, as their shares of the numerical value of the 
 observation. Suppose we have the following observations of 
 wind direction recorded : S., S.E., E., S.S.E., N.W., W.N. W., 
 N.E., E.N.E., N., N.E. Giving to each observation a numerical 
 value of 4 and deducting the opposite directions from each other, 
 we find the mean direction is six points nearer E. than N. As 
 each point on the compass equals n°'25, the precise mean 
 direction of the wind for these ten readings is 6 times n°'25 or 
 67°*5 from N., which on the compass is a mean direction of 
 E.N.E. 
 
 The instruments for the measurement of wind, either as 
 regards its force or pressure and velocity, are called anemometers. 
 The earlier forms of these instruments were rectangular plates, 
 whose movements, resisted by either springs or weights, recorded 
 upon a chart by means of a connected pencil the amount of their 
 displacement. In another form, the pressure of the wind is 
 measured by making it blow into the mouth of an open tube kept 
 facing the current by a vane, and noting the influence of the pres- 
 sure exerted upon a column of water or mercury in a siphon. 
 The later anemometers in use are those known as Robinson's, 
 consisting of four arms, each provided with a hollow cup and 
 rotating horizontally on a vertical axis, which, by means of an 
 endless screw, causes movements to be recorded upon a series of 
 dials in terms of miles and parts of a mile. These instruments 
 are graduated on the principle that, allowing for friction, the cups 
 revolve three times slower than the wind moves; so that if the 
 centres of the cups be 1*12 feet apart, each revolution corresponds 
 to 3*52 feet of movement, or 10*56 feet of actual wind motion, and 
 that 500 rotations of the cups indicate one mile of wind. Owing, 
 however, to the allowance for friction being placed probably too 
 high, and the cup motion being nearer 2 than 3 times slower than 
 the wind, the velocity of wind movement as recorded by many 
 instruments in general use is something like 20 per cent, too high 
 All anemometers to be reliable need to be kept scrupulously 
 clean, well oiled, and placed in a thoroughly open position some 
 20 feet from the ground. 
 
 Various proposals have been made for estimating and 
 
ANEMOMETERS. . 399 
 
 describing roughly the force of the wind. The earliest was that of 
 Admiral Beaufort, who, in 1806, devised a scale having a relation 
 to the pressure of the wind upon the sails of a ship, and the 
 amount of canvas which she could carry. 
 
 Attempts have been made to express the wind's force as a 
 pressure of so many pounds to the square foot. From experiments 
 with various kinds of anemometers, Dines calculates the pressure 
 P of the wind in pounds per square foot from the recorded velocity 
 in miles per hour, on the assumption that the pressure equals one 
 two hundredth (^~) of the square of the velocity, or P = 0*005 * 
 V 2 . According to this formula, a wind blowing with a velocity 
 of 50 miles an hour exercises a pressure of 12^ lbs. on the square 
 foot. 
 
 In England, the wind has an average velocity of 8 miles an 
 hour, and rarely exceeds 40. As a rule, at midday the wind blows 
 from sea to land, and from plains to hills, while in the evening 
 the direction will be reversed. In this country, the most preva- 
 lent wind throughout the year is the S.W., the next is the W. 
 The N.E. wind is the least prevalent, next the S.E., the E., and 
 the N. The W. and S.W. winds are largely the result of the Gulf 
 Stream, and are both warm and moist, while the E. and N.E. 
 winds which blow from the cold areas of northern Europe and 
 Asia are dry and cold. In all parts of the world there are 
 periodical and variable winds due to local causes, while the 
 permanent winds like the N.E. and S.E. trades take their 
 direction from the rotation of the earth, and are caused by the 
 constant movement of cold air from the poles towards the equator 
 to replace the heated air of the tropics. The trade winds vary 
 their prevalence over any particular area according to the season ; 
 but some other winds, such as the S.W. and N.E. monsoons of 
 India, are essentially seasonal. The former is a wet wind, while 
 the latter is in the main dry. The S.W. monsoon, usually com- 
 mencing in May, is caused by the surface of the whole continent 
 of India getting hotter than the sea, by which its air is rarefied, 
 and rises to be replaced by comparatively cooler air currents laden 
 with moisture blowing in from the Indian Ocean. The monsoon 
 having exhausted itself by the time it reaches the northern limits 
 of India, reverse currents of air begin to form, so that about 
 October the wind blows southward from the N.E., and continues 
 to do so until the same phenomena are started again in the early 
 summer by the increased heat of the land. Among other seasonal 
 winds may be mentioned the hot dry Khamsan wind of Egypt 
 which blows from the desert during the spring ; while in the 
 Mediterranean, the Bora and Mistral are two cold dry winds 
 coming from some portion of the Alps, the one being a N.E. wind 
 
400 . CLIMATE AND WEATHER. 
 
 affecting chiefly the Adriatic, and the other a N.W. wind blowing 
 powerfully over southern France. On the other hand, the E. or 
 S.E. winds in the Mediterranean, commonly called the Sirocco, are 
 hot, moist, relaxing, and proportionately unpleasant. 
 
 Clouds. — Although at present all attempts to estimate the 
 amounts of cloud are unsatisfactory, still continuous efforts are 
 being made to record their extent and conformations. As the 
 outcome of an International Meteorological Conference, held at 
 Munich in 1891, it is now usual to divide clouds into five large 
 groups, namely : (A) clouds existing very high in the air ; (B) clouds 
 at a medium height ; (C) clouds lying low or near the earth ; 
 (D) clouds in ascending currents of air; (E) masses of vapour 
 changing in form. A cloud is nothing more than the condensa- 
 tion of vapour into visible shape, and may occur in either of two 
 ways. Either a layer of the atmosphere is cooled in bulk to near 
 its dew-point, with the result that a stratified mass of cloud of 
 greater or less extent is formed, as the so-called stratus, or a body 
 of moist air is intruded into a mass which is cold and dry, result- 
 ing in a cloud of a heaped-up or cumulus form. 
 
 A close analysis of the various shapes or kinds of clouds has 
 resulted in their being divided into four principal forms, namely, 
 the stratus, the cumulus, the cirrus, and the nimbus, while from 
 these principal shapes result various modifications. 
 
 The stratus cloud can be best described as a widely extended 
 but continuous horizontal sheet of vapour, very often forming at 
 sunset. 
 
 The cumulus cloud is often very like a mountain in appear- 
 ance, rising from a horizontal base; they are familiar to most 
 people as conical heaps having often a bright or silver lining on 
 the aspect towards the sun. The vapour in cumulus clouds is 
 usually in the form of snow, and at its greatest density. 
 
 The cirrus cloud is best compared to a series of thin filaments 
 not unlike a brush. It is the loftiest of all kinds of cloud, 
 familiar examples being the so-called mares' tails, or parallel 
 and diverging strips extending in any direction. Cirrus clouds 
 are probably composed of ice or vapour in its least stage of 
 density. 
 
 The nimbus is the true rain-cloud, being usually a horizontal 
 sheet, having cumulus beneath and laterally, and with rain 
 actually falling from it. Besides these four chief forms, there are 
 compound modifications of them, the names of which are suffi- 
 ciently descriptive. 
 
 Halos and Coronae are circles which appear round the sun 
 and moon. Halos arise from the existence of minute prisms of 
 ice in the atmosphere, and consist of refracted light ; they usually 
 
ATMOSPHERIC PRESSURE. 4OI 
 
 portend unsettled weather in these latitudes. Coronae are more 
 common than halos ; they arise from the interference of rays of 
 light passing through a mass of minute globules of water, and 
 accordingly are seen whenever light clouds pass between us and 
 the moon. 
 
 Atmospheric Pressure. — It has already been explained that 
 the density or pressure which the atmosphere exerts is deter- 
 mined or noted by means of instruments called barometers. 
 These are usually either mercurial, glycerin, water, or aneroid 
 barometers. As commonly constructed, the mercurial barometer 
 consists of a tube of glass about 36 inches long, closed at one 
 end, filled with mercury, and placed vertically with the open end 
 dipping into a cup containing mercury, called the cistern. When 
 discussing the question of the weight of air, the principle of the 
 construction of this instrument was explained, as also was the 
 fact that the difference between the heights of the two mercurial 
 surfaces exactly measured the atmospheric pressure. This in 
 terms of mercury at sea-level, in this country, is 29*92 inches. 
 As the mercury in the tube balances, as it were, the pressure of 
 the air, it is obvious that it falls with a lessened pressure, but 
 rises with an increased pressure, so that if by means of a fixed 
 scale we note the precise length of the mercury column, we may 
 measure the weight of the atmosphere. Such a scale is commonly 
 divided into inches or other measures of length. In some 
 common forms of barometer, this scale is laid off from a zero at 
 some fixed point in the cistern, with the result that, except at one 
 particular point, the instrument reads wrongly, because during the 
 changes which take place in the length of the column, the level 
 of the mercury in the cistern also changes, being sometimes 
 higher and sometimes lower than the fixed zero point. In order 
 to overcome this difficulty and source of error, various expedients 
 have been resorted to, so as to compensate for the ever-changing 
 level of the mercury in the cistern • thus, (1) by a so-called 
 capacity correction which, duly noted and recorded on the scale 
 by the maker, states the ratio of the interior area of the tube 
 to that of the cistern, thus capacity -£$. To apply this correction, 
 there is always marked on the scale a certain height of the 
 column which is correctly measured by the scale. This exact 
 height is termed the neutral point ; when the mercury sinks below 
 this, the height read off will of course be too great, because trie 
 level of the mercury in the cistern will have risen above the zero 
 in a proportionate amount; for the same reason, when the 
 mercury nses above the neutral point, the reading will be too 
 small because the level of the mercury in the cistern will have 
 fallen below the zero of the scale. The capacity correction is 
 
40: 
 
 CLIMATE AND WEATHER. 
 
 applied by taking the indicated fractional part of the difference 
 between the height read off and that of the neutral point, and 
 adding or subtracting it from the reading, as the case may be. 
 Thus, suppose in the case of a barometer marked with a neutral 
 point, and with a capacity correction of •£§, the mercury stands 
 i inch above the neutral point, then -£§ of the difference the 
 
 height read off and the neutral point, or, in this 
 case, -—, or 0*02 inch, must be added to the ob- 
 served reading. (2) In the Kew barometers 
 the error is obviated by graduating the scale in 
 nominal inches, which are shorter than true 
 inches, from above downwards in proportion to 
 the relative size of the diameter of the tube and 
 cistern. (3) Another device is to do away with 
 the cistern altogether, and employ a U-shaped 
 tube, in which one arm is shorter than another 
 and open at one end. Both levels are read upon 
 a scale, and the reading of the barumeter is the 
 difference in level of the mercury in the two 
 legs. These are sometimes called siphon baro- 
 meters, of which the ordinary wheel barometer 
 is a common type; in this latter instrument the 
 movements of the mercury are transmitted from 
 a float on the mercury in the open tube, by 
 means of a string, to an axis which carries an 
 index moving over a dial-plate as in a clock. 
 (4) In what are called the Fortin barometers, 
 or best standard barometers, the necessity for 
 capacity correction, or either of the other above- 
 named devices, is avoided by giving the cistern 
 a pliable base of leather, and capable of being 
 raised or lowered by means of a screw c (Fig. 75). 
 The upper part of the cistern is made of glass, 
 through which the zero of the scale can be 
 seen as a piece of ivory, whose lower extremity is called the 
 fiducial point, d. Before taking a reading, the level of the mercury 
 in the cistern must be set exactly to this point, by raising or 
 lowering the cistern base by means of the screw ; since the fiducial 
 point is the tip of the piece of ivory, and accurately corresponds, 
 as a fixed point, to the zero of the scale, after the level of the 
 mercury in the cistern has once been carefully adjusted to it, it 
 is obvious that the height of the column of mercury then read 
 will be an accurate measure of the atmospheric pressure. 
 
 In order to secure a greater exactness in the reading of a baro- 
 meter, use is made of a secondary scale, or vernier, which slides 
 
 *m&> 
 
 Fig. 75 k — Diagram 
 showing cistern of a 
 Fortin's barometer. 
 
BAROMETERS. 
 
 403 
 
 upon the principal scale. In all standard barometers this vernier 
 scale is so graduated that 25 of its divisions correspond to 24 of 
 those upon the other, or fixed scale. Conse- D 
 
 quently, each space or division on the scale is 
 ■^ of its own size larger than each space on 
 the vernier, and as each such space on the 
 scale is ^, or of yf^ an inch, therefore the 
 
 r5- 
 
 vernier exhibits differences of ■— of ^0 inch, 
 or g£o, or C002 inch. In taking a reading of 
 a barometer, the first thing to do is to note the 
 temperature of the instrument by means of 
 the usually attached thermometer ; next, adjust 
 the mercury in the cistern to the fiducial point, 
 if it be one made on Fortin's principle ; then 
 place the vernier so that its lowest edge is level 
 with the top of the mercurial column. If this 
 level coincide exactly with one of the principal 
 scale-divisions, there is no need to use the 
 vernier ; but if it do not so coincide, the use of 
 the vernier will accurately measure the excess 
 of the mercury-level over the next lowest 
 division or mark on the scale. To do this, we 
 must follow the vernier scale up, until we find 
 one of its marks exactly corresponds with one 
 on the fixed scale ; call it x, and, as each of 
 
 3-1 
 
 -2- 
 
 H- 
 
 these represents 
 
 1 
 
 60 0' 
 
 or 0*002 inch, we have 
 
 B 
 
 A 
 
 
 
 
 
 30 
 
 29 
 
 1 
 
 15 
 
 10 
 
 05 
 
 00 
 
 Fig. 76. —Vernier at- 
 tached to a barometer 
 scale. 
 
 x X 0*002 inch as the exact distance which 
 the mercury column is over and above the 
 next lowest mark to it on the principal scale. 
 Thus, in Fig. 76, presuming that the lower 
 edge of the vernier, A B, has been accurately 
 adjusted to the level of the top of the mercurial 
 column, we find that that corresponds to a 
 point just below 29*20 inches, and something above 29*15 inches; 
 that is to say, neither of those readings gives the absolutely correct 
 height of the mercury. Following up the vernier, we find that its 
 seventeenth line or mark is the first to exactly coincide with one 
 on the principal scale CD • therefore, if we read that as meaning 
 J~q of an inch, or 0*034 inch, or the exact amount by which the 
 top of the mercury column exceeds 29*15 on the fixed scale, we get 
 by the addition of these two numbers 29*184 inches, as the correct 
 reading of this particular example. 
 
 The reading having been thus accurately taken, it remains to 
 apply certain corrections ; these are (1) index error, (2) for 
 capillarity, (3) for temperature, (4) for height above sea-level. 
 
404 
 
 CLIMATE AND WEATHER. 
 
 The first two corrections have to do with the actual instrument, 
 and are usually very small and determined before the instrument 
 is sent out, and their amounts duly entered on the certificate 
 which accompanies the barometer. The error due to temperature 
 is one which affects, not only the mercury, but also the brass of 
 the scale, and in extremes of heat or cold may be considerable ; 
 this explains why it is so important to note the temperature 
 before taking the reading. To secure uniformity of barometric 
 records all nations have agreed to reduce their barometer readings 
 to what they would have been had both the mercury and brass 
 scale been at 32 F., or o° C. All good barometers are made 
 with brass scales, and for these the necessary temperature cor- 
 rections are given in the following table: — 
 
 Temp. 
 
 27 inches. 
 
 28 inches. 
 
 29 inches. 
 
 30 inches. 
 
 31 inches. 
 
 30° 
 
 — 0*004 
 
 — 0*004 
 
 — 0*004 
 
 — 0*004 
 
 — 0*OC4 
 
 40° 
 
 — 0*028 
 
 — 0*029 
 
 — 0*030 
 
 — 0*031 
 
 — 0*032 
 
 50 
 
 — 0*052 
 
 -0*054 
 
 -0*056 
 
 -0*058 
 
 — 0*060 
 
 6o° 
 
 — 0*076 
 
 — 0*079 
 
 —0*082 
 
 -0*085 
 
 -0*087 
 
 70° 
 
 — O'lOO 
 
 — 0*104 
 
 — 0*108 
 
 — O'HI 
 
 -0-II5 
 
 8o° 
 
 — 0*124 
 
 — 0*129 
 
 -0*133 
 
 -0*I 3 8 
 
 -0*I43 
 
 90 
 
 — 0*148 
 
 -OT53 
 
 -0*159 
 
 — 0*164 
 
 — 0*170 
 
 IOO° 
 
 — 0*172 
 
 -0*178 
 
 — 0*184 
 
 — 0*I9I 
 
 -0*197 
 
 Corrections for height above sea-level are usually made by 
 reducing all readings to sea-level, which is the level of the mean 
 half-tide at Liverpool. If we know the exact height of the par- 
 ticular spot above or below sea-level, the necessary correction is 
 commonly obtained from specially prepared tables ; but the 
 application of this correction is very little needed in everyday 
 life, unless records are made for scientific purposes. As an 
 approximate calculation the correction may be said to be about 
 1 inch for every 1000 feet. 
 
 Although in the majority of barometers the atmospheric 
 pressure is measured by a column of mercury because of its 
 high specific gravity, still, in some others, other liquids are em- 
 ployed, such as glycerin, which, having a lower specific gravity, 
 is much more sensitive to variations in pressure. The specific 
 gravity or density of mercury is 13*59, while that of glycerin 
 is but 1*26; the atmosphere we know can support a mercurial 
 column 29*92 inches high; therefore, it can equally support a 
 glycerin column 27 feet high : or, in other words, a fall of 1 
 inch in a mercurial column is the equivalent of a fall of 107 
 inches in a glycerin instrument — the latter, in consequence of 
 
ANEROID BAROMETERS. 405 
 
 its greater range, being far more sensitive as an indicator. 
 Water barometers have also been made, in which the column 
 required to balance the atmosphere is 34 feet. Besides mer- 
 curial, glycerin, and water barometers, familiar instruments in 
 general use are aneroid barometers — their principle is very 
 simple. They are small, air-tight metallic boxes, exhausted of 
 air inside, and so constructed that as the atmospheric pressure 
 rises so the metal box is forced in, and, helped by means of 
 a strong spring, bulges out again when the pressure lessens. 
 The movements of the metal are, by a suitable arrangement of 
 levers, made to turn an index on a dial face. The dial is of course 
 graduated by comparison with a standard mercurial instrument. 
 Aneroids are very sensitive and convenient, but liable at times to 
 go hopelessly wrong, on which account they need to be periodi- 
 cally checked against a standard mercurial instrument. Mercurial 
 barometers may be said to measure absolute pressure, while 
 aneroids measure relative pressure. 
 
 By a combination of a series of aneroid vacuum boxes, the 
 movements of which by means of a lever are multiplied, and 
 recorded upon a revolving cylinder, so-called recording baro- 
 meters have been made, and for observatory work these instru- 
 ments serve a useful purpose, but, of course, are not absolutely 
 accurate without being constantly checked against standard 
 mercurial instruments. 
 
 Barometers generally, and aneroids in particular, have been 
 of the greatest value as measurers of the height of any given place 
 above the sea-level ; the barometer, of course, falls when heights 
 are ascended, but the diminution of pressure is not uniform. 
 Strictly speaking, such observations involve calculations of more 
 or less complexity, but, for rough work, fairly accurate results can 
 be obtained by simple rules. It is, however, necessary to make 
 three readings of the barometer. Suppose it is required to know 
 how much higher a town, A, is above a source of good water- 
 supply situated at B. Read the barometer at A, go then to B 
 and read it there, then back to A and read it there again ; take 
 a mean of the two readings at A, and determine the difference 
 between it and the reading at B ; this, multiplied by 9, and 
 neglecting decimals, will give the difference in height between 
 the two places in feet. Thus, suppose the first reading at A had 
 been 29*94, and the second had been 29*90, the mean, of course, 
 would be 29*92; -and suppose the reading at B to have been 
 30*35, the difference between these two is 0*43, which, multiplied 
 by 9 and ignoring decimals, gives 387 feet as the height of A 
 above B. When the barometer at the higher station is below 
 26 inches, or the temperature above 70 F., the multiplying factor 
 
406 
 
 CLIMATE AND WEATHER. 
 
 should be 10. The results by this method are correct to about 
 5 feet in ioo. 
 
 Results correct to about i foot in ioo can be obtained by (i) 
 estimating the mean temperature of the air; (2) ascertaining the 
 mean barometric pressure ; (3) using, instead of the factors 9 or 
 10, the figures in the following table, which correspond most 
 nearly to the values obtained for (1) and (2) : — 
 
 
 Mean temperature (Fahr.)- 
 
 
 3°° 
 
 40° 
 
 50° 
 
 6o° 
 
 7°° 
 
 Mean pressure, 27 inches 
 
 >j »i 2 9 >» • 
 »> j> 3° >> • 
 
 97 
 
 9*3 
 9-0 
 
 87 
 
 9*9 
 
 9'5 
 9-2 
 
 8-9 
 
 IO*I 
 
 9-8 
 
 9'4 
 9-1 
 
 10*3 
 
 IOO 
 
 9*6 
 9'3 
 
 io-6 
 
 IO*2 
 
 9-8 
 9*5 
 
 Example — 
 
 Temperature at Lower Station = 6o° Pressure at Lower Station 
 
 ,, Upper ,, = 56 ,, „ Upper „ 
 
 Mean temperature = 58 Mean pressure 
 
 Pressure at Lower Station = 30*25 
 Upper ,, = 29*02 
 
 »> 
 
 30*25 
 29*02 
 29*63 
 
 »» 
 
 >> 
 
 Difference = 1*23 
 Multiplier = 9*3 
 Altitude = 123 x 9*3 = 1143*9 f eet « 
 
 In most parts of the world there are distinct periodical and 
 non-periodical changes in the atmospheric pressure as indicated 
 by the barometer, but in these islands the former are barely 
 noticeable owing to the intensity of the non-periodical changes. 
 In reality the periodic changes are in the form of two maxima, 
 namely, at about 9 a.m. and 9 p.m., with two minima at 3 a.m. 
 and 3 p.m. In this part of the world the range between these 
 two is not more than 0*02 inch, but in the tropics it amounts to 
 quite o*i inch. The annual variation of pressure in this country 
 is most variable, but the maximum readings are usually about the 
 end of May or early in June, while the minima are at the end of 
 October or early in November. 
 
 Unless very extreme, variations in atmospheric pressure appear 
 to have only an indirect influence upon health ; but when the 
 barometric pressure is lessened to the extent of some inches, as in 
 mountain climbing and balloon voyages, or much increased, as in 
 diving-bells, or pneumatic tubes and chambers used in pier-driving 
 below water, marked effects are produced upon both the breathing 
 
Variations in atmospheric pressure. 407 
 
 and blood circulation of men. Under very low pressures, the 
 pulse rate and respirations are at first increased, becoming after- 
 wards gradually slower and stronger. After some lengthened 
 exposure to low atmospheric pressure, the thorax and lungs 
 become widened with deep respiration. The general results of 
 prolonged residence under low atmospheric pressure are good. 
 The thinning, as it were, of the atmosphere and the lessened 
 amount of oxygen available stimulates a development of the 
 inspiratory act and a more vigorous vascular system. These 
 effects are well seen in the broad and deep chests with well- 
 developed muscles of all mountain races. The effects of increased 
 atmospheric pressure are more marked, as evidenced by the deaf- 
 ness, ear pains, and sense of tightness round the head which are 
 experienced by those going down in diving-bells. In pneumatic 
 chambers and tubes used for pier-driving and laying the founda- 
 tions of bridges, the pressure in the air-chambers is usually of 
 from 3 to 4 atmospheres, and if due precautions are taken to 
 neither increase nor lower the pressure too rapidly, no symptoms 
 or inconvenience are experienced by workmen when employed 
 in them for hours together. What accidents and ill effects have 
 occurred are chiefly in the form of prickings, muscular pains, nose 
 bleedings, and paralysis, and these have occurred commonly after 
 leaving the high-pressure chambers or tubes, and when the reduc- 
 tion of pressure has been too rapid. Very few unfavourable 
 effects appear to occur under the actual high pressure. The great 
 danger in all these cases appears to be in the. too sudden reduction 
 of pressure. If time be given, the body seems to be quite able to 
 accommodate itself to the extreme variations of pressure : thus in 
 aeroplane ascents men have been able to withstand as low a 
 pressure as indicated by 6 inches of mercury ; while, on the 
 other hand, men who worked in sinking piers for the Forth 
 Bridge did so in air-chambers in which the barometer stood 
 as high as 72 inches. These two instances give a range of 
 atmospheric pressure extending over 66 inches, supportable by 
 man. 
 
 In everyday life, the variations of barometric pressure, though 
 rarely extending over a greater range than 3 inches, have a 
 practical value as indicating the general character of the Weather 
 and the probable presence or absence of rain. It has already 
 been explained how rain is dependent upon the presence of 
 moisture in the air, and upon how well the air can retain that 
 moisture. It has, too, been explained that when dry air receives 
 moisture its volume increases, with the result that an amount of 
 air which, when dry, measures 1 cubic foot, and weighs, at 50 F., 
 546*8 grs., becomes, when saturated with watery vapour at the 
 
408 
 
 CLIMATE AND WEATHER. 
 
 same temperature, 1*1021 cubic feet, with a weight of 550^9 grs. ; 
 so that 1 cubic foot of the saturated air weighs but 544'3, or 23 
 grs. lighter than it did when dry. It is this physical fact of moist 
 air weighing lighter than dry air that causes the barometer to 
 fall in consequence of lessened atmospheric weight when much 
 moisture is present, and, consequently, rain imminent. It must, 
 however, be remembered that other causes than moisture will 
 often affect the barometer, notably wind, though, in the main, its 
 movements are dependent largely upon the presence or absence 
 of watery vapour in the air. It was the early recognition of this 
 fact that led to the use of the barometer as a weather-indicator. 
 In former years the value of the barometric reading was neces- 
 sarily limited to the particular spot at which it was noted ; but 
 recently, as the result of increased facilities of communication 
 between one place and another, it is possible to obtain simul- 
 taneous readings of the barometer at any given time at several spots 
 distributed over a wide. area. Now, if these are recorded on a 
 map, and lines be drawn between and connecting all places where 
 the same pressure prevails, we obtain what is called a synoptic 
 chart, made up of lines of equal barometric reading, or isobars, as 
 they are termed. This is what is actually done in all the chief 
 meteorological stations, and experience has shown that these 
 isobars commonly assume certain typical forms or shapes, which 
 are again usually associated with certain kinds of weather. It is 
 upon these data and facts that the modern methods of weather 
 forecasting are based. 
 
 Isobars, or lines drawn on a chart indicating places of equal 
 barometric pressure, are found to arrange themselves practically 
 
 Antic 
 
 30j 
 
 
 ..— v *- Sy \ \ y /*99 
 
 ^—. <.. '< . \ — y 
 
 Zo.g 
 
 •°l \Cycf. 
 
 Isobar^- 
 Fig. 77. — Diagram showing the chief types ot isobars. 
 
 A)./" 
 
 into seven different shapes called cyclones, secondary cyclones, 
 V-shaped depressions, anti-cyclones, wedges of high pressure, 
 
CYCLONES. 409 
 
 cols and straight isobars ; the general characteristics of each are 
 shown in Fig. 77. The closeness of the isobars one to another, 
 or the rapidity of changes in pressure, constitute what is called 
 the "barometric gradient," and just as we measure and express 
 a railway gradient as being 1 in 20, 1 in 100, and so on, so can 
 we say that barometric gradients are so many thousandths of an 
 inch in 15 miles, or so many millimetres in one degree of the 
 meridian. The steepness of the barometric gradients directly 
 governs the velocity of the wind over any particular place, the 
 wind's velocity being greatest at the localities of steepest gradient, 
 and vice versd. In addition to this, if the wind's direction at each 
 place be noted on a synoptic chart, it is found to be nearly 
 parallel to the trend of the isobars, and tends to cross from the 
 higher to the lower ones. This fact has found expression in what 
 is known as Buys Ballot's law, namely, that if you stand with your 
 back to the wind, the lowest pressure lies to your left and in front. 
 Cyclones. — An area of low pressure, and the whole system 
 connected with it, is called a depression or cyclone, and in 
 America " a low." As seen on a synoptic chart, cyclones are 
 circles formed by concentric isobars, in which the outer lines 
 mark a higher pressure than the inner ones ; they constitute the 
 most frequent arrangement of isobars in these latitudes (Fig. 78). 
 They usually travel from west to east, at the rate of about 20 
 miles an hour, and are invariably associated with bad weather. 
 From what has already been said, it is evident that the actual 
 pressure or height of the barometer is of little moment ; the forces 
 involved are due to the gradients or differences of pressure, and 
 are greater the steeper the gradients. Hence a cyclone may be 
 of a mild type, or be a gale or hurricane, according as to whether 
 the gradients are gentle or steep. If we analyze the weather 
 associated with a cyclonic disturbance, we find that the foremost 
 portion of a cyclone area is always marked by stratiform clouds, 
 moist heavy atmosphere, and the usual signs of coming rain, such 
 as a pale moon, watery sun, dirty gloomy sky. As the cyclone 
 advances, a drizzling gradually changes into a driving rain, 
 accompanied in the trough or situation of lowest pressure by 
 squalls of wind. As the cyclone area shifts its position or moves 
 onward, the rain moderates into showers, followed by a brighter 
 sky with cumulus clouds and a sharp brisk feeling in the air. If 
 we study the barometer changes at different points in the path of 
 a cyclone, it is at once obvious that in the fore part of the area 
 of depression the barometer is everywhere falling, while in the 
 rear part it is everywhere rising, and the turning-point, or line of 
 lowest pressure, is what is called the trough. A cyclone may be 
 compared to a cup-shaped hollow, the isobars being simply 
 
4io 
 
 CLIMATE AND WEATHER. 
 
 contour lines. The extent or area of a cyclonic disturbance 
 may vary from 10 or 20 to some thousands of miles, covering 
 even the whole Atlantic or the greater part of Europe. Cyclones 
 are usually oval and not circular in form, their longest diameter 
 being in these latitudes in a direction nearly W.S.W. to E.N.E. 
 in the majority of cases. When the dimensions become great, 
 especially if the system be much elongated, a cyclone frequently 
 breaks up into two, three, or even more separate centres of 
 depression. Large cyclones are, of course, much modified in 
 both form and position by the variations of the deflecting force 
 due to the rotation of the earth, and arising from difference of 
 latitude. As a rule, the higher the latitude, the greater is the 
 average size of cyclones. In the tropics, cyclones are usually 
 smaller and circular. It is important, however, not to confound 
 small cyclones with either waterspouts or tornadoes, which are 
 too small to be much influenced by the rotation of the earth, 
 
 SIX'S 
 
 BLUE. 
 
 overcast X°^ FRONT 
 
 PALE MOON \<J, 
 STRATO- CUMULUS 
 
 \.>T 
 
 Blue 
 
 wikioy cirrus 
 
 Fig. 78. — Diagram showing weather typical of a cyclone. (After Abercromby.) 
 
 besides which they are special phenomena of a distinct nature. 
 The direction of the wind is, in all cyclones, obliquely across the 
 isobars, and may be described as blowing spirally into the area of 
 low pressure towards the centre, and from the central area in an 
 upward direction. The particular angle at which the incurving 
 of the wind takes place in a cyclone depends on the friction 
 
SECONDARY CYCLONES. 411 
 
 between the air-currents and the earth's surface, the angle being 
 smaller the greater the friction. Thus, according to Ley, the 
 angie between the direction of the wind and the isobars is 29° 
 for coast stations, and 13 for inland stations, thus showing 
 distinctly the increased effects of friction on land. It has already 
 been stated that cyclones in these latitudes for the most part 
 move in an easterly direction ; when a westward motion occurs, 
 it is usually slow and seldom long-continued. The advance of a 
 depression is commonly in a direction perpendicular to the line 
 of steepest gradient, so that the highest pressure lies to the right ; 
 while also the temperature is highest to the right of its track. 
 The rate of advance of a cyclone varies within very wide limits ; 
 on the whole, deep depressions move faster than shallow. The 
 average rate of motion of translation of cyclones over Europe 
 is from 20 to 30 miles an hour, while in America they travel 
 commonly as rapidly as 50 miles an hour. So far as is known, 
 cyclonic storms and weather seldom or never originate within five 
 degrees of the equator, but this intermediate tropical belt is the 
 scene of extremely violent hurricanes, which have a tendency to 
 move in a westerly or north-westerly direction, and, moreover, 
 appear to behave according to laws too complex to be given in 
 detail here. The general weather characteristics of a northern 
 cyclone area are given in Fig. 78, which shows such an arrange- 
 ment of isobars shifting in a north-easterly direction. 
 
 Secondary Cyclones are areas of low pressure formed by looped 
 or incompletely circular concentric isobars with the lowest pressure 
 in the centre. They have many weather features in common 
 with primary cyclones, moving like them mostly from west to east. 
 They frequently follow primary cyclones, and their bad weather is 
 usually associated with calm and stationary barometers. 
 
 V-shaped Depressions are angular intervals or areas with the 
 lowest pressure in the interior, and frequently form between 
 adjoining anticyclones, and are, as it were, a specialized form of 
 cyclone, or even may form part of a cyclone. They have been 
 aptly described as tongues of depression projecting from a cyclone 
 situated to one side ; in the northern hemisphere the point or tip 
 is usually towards the south. These V's commonly move from 
 east to west, and the weather experienced by an observer over 
 whom one of these areas of depression drifts is from blue sky to 
 cloud, later on rain with a falling barometer and south-west wind, 
 then a squall, during which the wind jumps round to north-west, 
 followed by a rapidly clearing sky and a rising barometer. This 
 type of isobars is always associated with squalls or thunderstorms. 
 Not only secondary cyclones but V-shaped depressions are in 
 general most uncertain in their movements, and their occurrence 
 
412 
 
 CLIMATE AND WEATHER. 
 
 is consequently very difficult to foretell. The extreme rapidity 
 with which they travel at times, and the violence of the wind and 
 rain developed within them, render them a source of great danger 
 to both life and property. The peculiar summer thunderstorms 
 of Central Europe and America are nearly always associated with 
 V-shaped depressions. 
 
 Anticyclones. — These are areas of high pressure formed by 
 more or less circular isobars, with the highest pressure in the 
 centre. They differ from all other arrangements of isobars in 
 tending to remain stationary and, too, to extend over large areas. 
 The air is calm and cold in the centre, while on the borders the 
 wind blows round the centre spirally outwards in the direction of 
 the hands of the clock ; thus, on the east side the wind comes 
 
 30-0 
 
 Fig. 79. — Diagram showing weather typical of an anticyclone. (After Abercromby.) 
 
 from the north, on the south from the north-east, on the west 
 from the south-east, and on the north from the west. In 
 describing the cyclonic system it was explained how the wind in 
 the centre of that system was an ascending current ; that wind 
 circulation is compensated by an equivalent descending current 
 in what is in all respects the opposite of the cyclone, namely, the 
 anticyclone. The characteristic circulation of the air in this is 
 
WEATHER FORECASTING. 4*3 
 
 therefore exactly the reverse of that in a cyclone : it blows in the 
 same direction as the hands of the clock, more spirally outwards 
 from the centre at or near the surface of the earth, and in- 
 wards towards the centre at the level of the highest clouds. In 
 anticyclonic systems the barometric gradients are slight, and the 
 normal wind circulation usually disturbed or disguised by acci- 
 dental or local causes. The general weather features of an 
 anticyclone are given in Fig. 79, from which it will be seen that 
 they are the exact opposite of cyclonic conditions, being blue 
 sky, dry cold air, a hot sun, little or no wind, and a hazy horizon — 
 in fact, fine weather. The diagram shows in one half the summer 
 characteristics of an anticyclone, in the other those of winter. 
 Certain regions of the globe are remarkable for the existence of 
 permanent and recurrent anticyclone systems. There is a 
 permanent area of high pressure near latitude 30 north, called 
 the Atlantic Anticyclone, which varies in extent from month to 
 month, attaining its greatest intensity in summer and least in 
 winter. Another permanent area is that over the large land 
 surface of Asia and Eastern Europe in which the pressure is 
 usually excessive during winter. It is the existence and more or 
 less permanency of these two large areas of high pressure which 
 combine to give a north-westerly gradient towards a stationary 
 low-pressure centre near Iceland and to govefli the motions of 
 cyclones, which tend to skirt round their borders in an easterly 
 direction. It is important to remember that, while an an%:yclone 
 system compensates a cyclone in the matter of transferring air 
 from one level to another, there is no mutual relation between 
 them in the sense of cause and effect. 
 
 Wedge-shaped Isobars usually point to the north and indi- 
 cate areas of high pressure moving along between two adjacent 
 cyclones. Though very usually associated with fine weather, 
 it is only temporary because wedges of high pressure are never 
 stationary, and are commonly followed by well-defined cyclonic 
 areas. So far as weather is concerned, we may regard the two 
 sides of the wedge as the rear and front of cyclones, and the 
 wedge itself as a mere projecting tongue of an anticyclone. The 
 wide end of the wedge is often associated with fog, and the narrow . 
 end with thunderstorms or showers. 
 
 Cols, or necks of comparatively low pressure, generally lie 
 between two anticyclonic areas. Over them the weather is dull, 
 gloomy, and stagnant, while in summer violent thunderstorms 
 are frequently associated with them. Like the following, cols are 
 essentially intermediate systems. 
 
 Straight Isobars are those without any curve, and may trend 
 in any direction. This arrangement of isobars only marks the 
 
414 CLIMATE AND WEATHER. 
 
 position of a barometric slope, and does not include any area 
 of either high or low pressure. This form is essentially temporary 
 and an intermediate arrangement of the atmospheric circulation 
 or pressure which precedes the formation of a cyclone. The 
 weather associated with straight isobars is too transitional to be 
 characteristic, but very frequently is that of a hard sky, with a 
 blustering wind and an inclination to rain, such as one experiences 
 as to remark that " when the wind falls it will rain." 
 
 What are known as squalls, or puffs of wind of varying 
 intensity, appear to be caused by the sudden breaking of the 
 cold dense upper layers of air through lower and warmer layers 
 lying underneath, condensing the vapour in the latter and causing 
 them to ascend. In contrast to them are the various kinds of 
 squall attributable to the sudden ascent of masses of warm air ; 
 examples of this phenomenon we know, as the familiar dust 
 whirls on a dry road, or the dust storms, waterspouts, and 
 tornadoes of the tropics. Their causation is unknown. 
 
 It must not be forgotten that all the foregoing forms of 
 isobars are at any time liable to break up, or at least pass into 
 new forms, so 'that, although every part of every shape of isobars 
 has a characteristic weather and sky appearance, still, owing to 
 their often rapid breaking up, forecasting of weather is not always 
 certain to come 'true. Cyclonic disturbances, for instance, are 
 frequently diverted from their course by meeting a coast line or 
 range of mountains, or even by the formation of areas of high 
 pressure ; so that their velocity is neither regular nor their 
 direction of movement necessarily straight. On the other hand, 
 experience shows that when advantage is taken of Transatlantic 
 and other meteorological observations telegraphed to a central 
 meteorological office, synoptic charts can be prepared of such 
 magnitude and detail as to render weather forecasting com- 
 paratively successful in a great percentage of cases. All meteoro- 
 logical phenomena are practically the products or results of the 
 circulation or motion of a moist atmosphere, and consequently 
 forecasting weather is nothing more than saying how and where 
 certain air-currents or eddies will move, or when new ones will 
 form, and whether they will be gentle or violent. From the 
 rapidity with which meteorological changes take place, the use 
 of telegraphy is absolutely necessary if any success is to be 
 attained in forecasting, and even this information can be only 
 of use in some central office presided over by an experienced 
 forecaster thoroughly conversant with the motions of low-pressure 
 areas in his own country. It will be readily understood that 
 in some countries forecasting is easier than in others. Thus, 
 
VITAL STATISTICS. 415 
 
 in the temperate zone, where most disturbances move from the 
 west, those countries will be best suited for weather forecasting 
 which lie to the east of a well-observed land area. For this 
 reason Norway and Germany are better placed for weather fore- 
 casting than either France or England. Large areas of land and 
 water mainly determine the great areas of high and low pressure, 
 hence Great Britain being placed where it is, on the boundary, 
 so to speak, between anticyclonic and cyclonic systems, renders 
 the prognostication of weather peculiarly difficult in these islands, 
 more particularly as their geographical position precludes an early 
 knowledge of cyclones forming over the Atlantic. Moreover, just 
 as an outlying rock is exposed to the wash of every sea, so is 
 England exposed to the disturbing influences of every type of 
 European or Atlantic weather, and has, in consequence, more 
 unsettled weather than any other part of Europe. 
 
 CHAPTER XI. 
 
 VITAL STATISTICS. 
 
 Probably no single cause has contributed more to the attention 
 now paid to questions of public health than the careful collection 
 of the statistics of births and deaths, and of the causes of death 
 which have been collected and published by the Registrar- 
 General's Office in England during the past fifty years. These 
 collections of figures and facts are usually spoken of as vital or 
 health statistics, because they are so intimately associated with 
 the various problems relating to the health and chances of life 
 which the community enjoys. So valuable has been the work 
 done, that we are now able to determine with some precision the 
 causes and limits of mortality, and by the study and analysis 
 of the collection of facts known as vital statistics to apply them 
 as tests of the health of the communities to which they refer. 
 
 The chief vital statistics, bearing upon public health, relate in 
 detail to past and present facts concerning populations, age and 
 sex distribution, births, marriages, deaths, diseases, duration of 
 
41 6 VITAL STATISTICS. 
 
 the hours of occupation and general social conditions, such as 
 the health of each class of the community as judged of by the 
 expectation of life at given ages. Statistics of sickness, apart 
 from mortality, have as yet not been attempted, chiefly on account 
 of the difficulty in collecting the data with accuracy. 
 
 Population. — The very first necessity is to know what is the 
 precise number of the people. Our knowledge upon this point 
 in each place in Great Britain depends primarily upon the census 
 returns which have been made regularly and with increasing care 
 every ten years since 1801. It will be at once obvious that the 
 facts relating to the numbers living of each sex and age periods 
 and the numbers employed in certain callings can only be 
 accurately known in actual census years, and making from 
 them estimates for intermediate years. An interval of ten years 
 between the takings of the census is now acknowledged to be too 
 long, and it is probable that if our population statistics are to 
 remain in any way accurate, more frequent enumerations of the 
 people will need to be taken, and even then certain inaccuracies 
 are sure to exist, due chiefly to the imperfect education of large 
 numbers of householders and heads of families, these defects 
 of information collected relating especially to occupations and 
 ages. It is remarkable what a large number of people do not 
 know their precise age, these persons generally giving their age 
 in census returns in some multiple of ten. Another source of 
 error and perplexity in all census returns is the too frequent 
 wilful misstatements made by women, owing to their desire, for 
 various reasons, to be thought between 20 and 25 years of age. 
 This is shown by the fact that in each successive census, the 
 number of women returning themselves as between 20 and 25 is 
 larger than the number of girls returned in the census of ten years 
 before as between to and 15 years of age. The former being 
 only the survivors, after the lapse of ten years of these latter, they 
 should of necessity be fewer in number. The male sex is not 
 altogether free from blame in the same matter, though the bias 
 goes in the opposite direction. Thus, men of the poorer classes, 
 who have passed the age of 60, constantly overstate their age for 
 the sake of certain definite advantages, such as getting old-age 
 pensions, outdoor relief, or, if entering the poor-house, gaining 
 some special privilege not granted to their juniors. Some really 
 old people often exaggerate their age in order to appear as 
 centenarians. 
 
 In attempting to estimate the population of any given locality 
 for any year intermediate between the collection of census returns, 
 it is necessary to calculate the probable decrease or increase of 
 the particular population by comparing the numbers of the latest 
 
ESTIMATED POPULATION. 417 
 
 enumerations. Thus, say a town had in 1901 a population of 
 
 35,626, and in 191 1 one of 38,754, and it was required to know 
 
 its estimated population in June, 19 18: it is only fair in such a 
 
 case to assume that the 19 18 population will be greater than the 
 
 191 1, and, if we further assume that the increase will be at the 
 
 same rate as between 1901 and 191 1, by taking the difference 
 
 between the 1901 and the 191 1 populations and dividing by ten, 
 
 we get the annual increase of population for that town. Inasmuch 
 
 as the census is always taken in the first quarter of the year, and 
 
 we require the population at the end of June, 191S, an interval of 
 
 7^ years will have elapsed since the last census; if, therefore, we 
 
 multiply the annual increase of population, which in this example 
 
 38754 — 3^626 _ . . r 
 
 is ^ ^ = 312*8, by 7*25, we get an increase of 2267 
 
 to be added to the 19 11 population, giving an estimated popula- 
 tion of 38,754 + 2267, or 41,021 for the middle of 1918. 
 
 The foregoing method of calculating an estimated population 
 is fallacious, as it presumes the increase or decrease will be as in 
 an arithmetical progression. The true law of population increase 
 or its decrease is that of a geometrical progression, and is very 
 suitably compared to the increase of a sum of money at compound 
 interest. The increase in x years is derived from the increase in 
 one year by multiplying 1 plus the annual rate of increase x times 
 into itself. If the increase in one year be 1*5 per cent., 1 becomes 
 1 "oi 5 in one year, and 1*015 multiplied x times into itself will give 
 the increase in x years. To obtain, therefore, the annual rate of 
 increase in x years, the xth root, and not the xth part of the x rate 
 of increase, must be taken. It is on this assumption, that the 
 increase or decrease of a population proceeds as in a geometrical 
 and not in an arithmetical progression, that the Registrar-General 
 calculates the estimated populations for London and other large 
 towns, as well as for the whole country, for intercensal years. On 
 this basis the calculations are more conveniently performed by 
 logarithms in the following manner : — 
 
 Taking the same example as above, we find the logarithm for 
 the 191 1 population, or log 38,754 = 4*5883165, and deduct 
 from it the logarithm for the 1901 population, or log 35,626 =• 
 4'55 I 767i; this gives 0*0365494, which is the logarithm of the 
 decennial increase. Dividing this by 10 gives us 0*0036545, or 
 the logarithm of the annual increase, and a quarter of this is 
 0*0009136, or the logarithm of the quarterly increase. By adding 
 together the logarithm of the 19 n population and seven times the 
 logarithm of the annual increase and the logarithm of the quarterly 
 increase, we get the logarithm of the mid-year 19 18 population, or 
 4*6148116, which, by reference to a set of tables, = a population 
 
 p 
 
4 I 8 VITAL STATISTICS. 
 
 of 41,260, or somewhat higher than the estimation made by that 
 of a simple arithmetical progression. 
 
 Unfortunately, these assumptions as to a uniform increase or 
 decrease of numbers are largely arbitrary or conjectural, and but 
 rarely agree with the actual facts as found by the next census. 
 Thus the population of Cardiff as estimated in 1901 by the 
 Registrar-General was 200,808, but when actually enumerated by 
 that year's census was found to be 164,420 only; that is, the rate 
 of increase of population during the ten years 1 891-1900 had been 
 much less than in the preceding decennial period. In a similar 
 way the total population of England and Wales at the census of 
 1901 was found to be 32,526,075, showing a rate of increase 
 during the ten years 1 891-1900 of 12" 17 per cent, as against 
 1 1 '65 between the 1881-90. In 191 1 the population was found 
 to be 36,070,492, showing that in the last decennium the rate 
 of increase had dropped to 10*9 per cent. 
 
 The same thing was found to have occurred in regard to the 
 populations of most of the large towns, with the result that their 
 calculated death-rates had been returned too low. These errone- 
 ous estimates of population have obvious vitiating effects on vital 
 statistics. The only remedy is a more frequent enumeration, as 
 offered by a quinquennial census. 
 
 As the Registrar-General has pointed out, the official method 
 of calculating populations by the assumption of an equable rate 
 of growth is only trustworthy in the case of very large communities, 
 where any abnormal increase in one direction is sure to be counter- 
 balanced by an abnormal decrease in another. It is hardly suited 
 for very small communities, where growth is very often most 
 irregular and spasmodic. 
 
 A moment's reflection will show that many circumstances 
 may help to quicken or slow the increase of a population. The 
 increase in any given population may be either ?iatural or actual. 
 The former is merely the excess of births over deaths, while the 
 latter is dependent upon the balance between births and immigra- 
 tion on the one hand, and deaths and emigration on the other. 
 The facts revealed by the last census, in 19 n, showed a decline 
 •in the natural increase of population for England and Wales ; this 
 was not due to any increased mortality, but rather to a decline 
 in the birth-rate. For the whole country the actual increase, as 
 shown by the last census, also showed a decline, due mainly to an 
 excess of emigration over immigration during the last decennium. 
 As a general rule, in towns the actual increase is greater than 
 the natural^ simply because there is a natural tendency for 
 people to migrate from rural to urban districts; and with regard 
 to such local migrations, at present we have no available or 
 
AGE AND SEX DISTRIBUTION. 
 
 419 
 
 systematic record. It is well known that in times when trade 
 is bad in certain localities, a considerable movement of the 
 population occurs to other parts, and vice versa. 
 
 Although not officially recognized by the Registrar-General, 
 there are several methods of checking estimated populations, 
 which, if used judiciously, are of great value. Amongst such are 
 examinations of inhabited houses as ascertained from the rate- 
 books, and then, assuming the density to remain the same, to 
 multiply the number of inhabited houses by the average number 
 of persons per house. Care, however, must be taken to allow 
 for any marked change in the class of new houses built, whether 
 containing fewer or more occupants than others, and, too, to 
 allow for block buildings, flats and large hotels, all of which are 
 liable to seriously affect statistical results. 
 
 Ag"e and Sex Distribution. — This is sometimes spoken of as 
 the constitution of a population, inasmuch as it shows the proportion 
 in which males and females, and persons of different ages or of 
 different callings, enter into the composition of the community. 
 These figures and facts are of course only obtained at each census, 
 and generally may be taken to remain constant till the next census. 
 The effect which these facts have upon mortality statistics will 
 be explained later on ; at present, allusion need only be made to 
 the very marked difference which exists in the age distribution \ 
 between the populations of town or urban and those of rural 
 districts. The 19 n census gives for England and Wales the 
 following age and sex distribution of the population in town and 
 country : — 
 
 
 Urban districts. 
 
 Rural districts. 
 
 
 Persons. 
 
 Males. 
 
 Females. 
 
 Persons. 
 
 Males. 
 
 Females. 
 
 All ages 
 
 28,162,936 
 
 13,628,189 
 
 14,534.747 
 
 7,907.556 
 
 3,957,483 
 
 3,95o,o73 
 
 oto 5 . 
 
 3,022,864 
 
 1,505,267 
 
 1,5*7,597 
 
 831,519 
 
 416,601 
 
 414,918 
 
 5 ,, 10 . 
 
 5>57I>632 
 
 2,776,720 
 
 2,794,912 
 
 1,624,852 
 
 8l4,86l 
 
 809,991 
 
 10 „ 15 . 
 
 2,614,322 
 
 1.295,793 
 
 1,318,529 
 
 722,299 
 
 398,263 
 
 324,036 
 
 15 ,, 20 . 
 
 2,537,2/5 
 
 1,179,035 
 
 1,358,240 
 
 638,4i3 
 
 338,075 
 
 300,368 
 
 20 ,, 25 . 
 
 2,469,831 
 
 1,198,205 
 
 1,271,626 
 
 60 ,229 
 
 290,2-5 
 
 318,984 
 
 25 » 35 • 
 
 4i 3 8 3,i89 
 
 2,106,798 
 
 2,276,391 
 
 1,107,256 
 
 542,U9 
 
 565,137 
 
 35 ,, 45 
 
 3, 2 5 6 ,o67 
 
 1,578,868 
 
 1,677,199 
 
 902,133 
 
 445,766 
 
 456,367 
 
 45 „ 55 • 
 
 2,206,390 
 
 1,052,031 
 
 i,i54,359 
 
 674,721 
 
 33', 486 
 
 343,235 
 
 55 ,, 65 . 
 
 1,352,459 
 
 616,978 
 
 735,48i 
 
 474,309 
 
 229, 0S2 
 
 245,227 
 
 65 >. 75 • 
 
 610,218 
 
 263,821 
 
 346,397 
 
 253,264 
 
 120,074 
 
 133,190 
 
 Over 75 . 
 
 138,689 
 
 54,673 
 
 84,016 
 
 69,531 
 
 30,9" 
 
 38,620 
 
 The table shows that, as compared with the country districts, 
 
420 VITAL STATISTICS. 
 
 in the towns of England and Wales there is a great excess of 
 persons from 15 to 45 years of age, and a small proportion of 
 children between 5 and 10 years of age. The probable explana- 
 tion of these figures is the persistent immigration of young adults 
 from the country to the urban areas in the one case, and the 
 higher infantile mortality of the towns than of rural districts in 
 the other. The proportion of females to males, of all ages, is 
 much higher in towns than in the country, being 108 to 100 
 in the former, but only as 101 to 100 in the latter. These pro- 
 portions are only manifest after the 10 to 15 age period, when the 
 girls begin to migrate into the towns as domestic servants. The 
 migration of girls into towns is soon followed by that of boys, with 
 the result that the unequal proportion of the two sexes in towns 
 in the 15 to 20 age period is considerably reduced, and continues 
 to be so during all the more active working ages, or the period 
 from the end of the 25th to the end of the 45 th year of life. In 
 the later years of life, the disproportion between the sexes in the 
 towns again increases, so much so that in the 55 to 65 years period 
 the women are 20 per cent, more numerous in towns than the 
 men, but only about 5 per cent, more numerous in the country. 
 In the 65 to 75 period the excess is 33 per cent, in the towns, and 
 only 7 per cent, in the country; while in the over 75 years period 
 the excess of women becomes 55 per cent, in the towns, and only 
 15 per cent, in the rural districts. 
 
 As the Registrar-General has pointed out, this increasing 
 excess of females in the late-age periods, so far as it is common 
 to both towns and country, is, of course, due to the fact that 
 women are longer lived than men — that is, they survive when the 
 men die off. The greater excess of women over men in towns than 
 in the country is less easy of explanation. It may be due to the 
 fact that men, as they get old, leave the towns where the struggle 
 for existence is so much the more keen, and retire into the 
 country more rapidly than do the women ; or it may be due to 
 differences between the conditions of town and country life being 
 more hostile to old men than to old women. Possibly both 
 causes are at work. We know that for some reason or other 
 urban life is exceptionally fatal to elderly men, and that towns 
 offer, even to those in advanced age, more chances of compara- 
 tively easy work to women than to men ; hence there is more 
 inducement for women than for men to remain in the towns when 
 they have grown old, especially as town life is much less healthy 
 for men than for women. The practical importance of this 
 question of age and sex distribution in vital statistics will be 
 apparent when we come to consider the value of death-rates. 
 
 Birth and Marriage Rates. — The Births and Deaths Registra- 
 tion Act of 1874 compels every birth to be registered within 42 
 
BIRTH AND MARRIAGE RATES. 421 
 
 days of its occurrence. The number of births per 1000 persons 
 living, or birth-rate, as it is so called, averaged 287 per 1000 in 
 England and Wales, during the decennium 1896-1905, the highest 
 rate of 36*3 ever recorded in this country having been reached in 
 1876 and the lowest or 177 in 1918. This latter rate indicates 
 a fall of over 25 per cent, since 1914. If we assume that under 
 peace conditions the decline would have continued at the average 
 pre-w r ar rate, then 4^9 of the total decline of 6'i since 19 14 must 
 be attributed to the war. The birth-rate varies in different towns 
 or localities, being higher in towns and during times of com- 
 mercial prosperity, and of course lower in rural districts and 
 during periods of trade depression. Bad trade and bad harvests 
 also diminish the number of marriages, and consequently lower 
 the number of children born. 
 
 The birth and marriage rates are readily found by a simple 
 proportion sum ; thus, if the population of a town be 13,621, and 
 the number of births and marriages during the year are respec- 
 tively 441 and 215, then yfjjy X 1000 = 32*3 birth-rate per 
 1000, and yfjfy X 1000 =157 marriage-rate per 1000. This 
 method of stating the ratio of births, marriages, or deaths in 
 one year, as per thousand persons living in a place, is the most 
 usual and convenient, but occasionally it may be necessary to 
 compare these rates for shorter periods, say weeks, months, or 
 quarters ; in which case it is done in the following way. Suppose 
 
 it is required to know the birth-rate during- part of a year, then — 
 
 it* 
 
 Number of births during the period in question 
 
 Population in the middle of the year 
 birth-rate of period in question. Taking the preceding example^ 
 
 and required the birth-rate during one week, or part of a 
 
 5 52-17747 F 
 
 year, during which period 10 births have taken place, we get 
 
 Yj~ X 52*17747 x 1000 = 38-19 or birth-rate. 
 
 When comparing one community with another, to be strictly 
 fair, the birth-rate should be calculated on the total population 
 only after it has been reduced to a common or normal constitu- 
 tion as regards sex, age, and marriage. This is the best secured by 
 calculating the birth-rate on the number of women between 20 
 and 40 years of age who constitute the great majority of child- 
 bearing mothers. More males appear to be born than females, 
 in the proportion of 104 to 100. The number of illegitimate 
 children born is increasing, having increased by n*6 per cent, 
 in 1918, while legitimate births have decreased by i-6 per cent. 
 This illegitimate birth-rate varies much in different districts ; thus 
 the registration counties in which the proportion of illegitimate to 
 
422 VITAL STATICTICS. 
 
 total births was highest, were Nottinghamshire, Norfolk, Suffolk, 
 Shropshire, Staffordshire, and Radnorshire. 
 
 Closely connected with the birth-rate is that of the marriage- 
 rate, and both are intimately involved in the question of population 
 increase. In this country, the number of married persons per 
 iooo of living has averaged during the last 50 years something 
 like 16 or 17 • but of late years it has steadily fallen. In 1918, 
 15*3 persons per 1000 living married. like the births, the 
 marriages usually closely follow the fluctuations in commercial 
 prosperity, but it is affected also by the proportion of marriageable 
 persons in the population. The rates for 19 18 were 51*9 for 
 males and 41 - o for females. The mean age at marriage is 
 30 for males and 27 for females. The most disquieting feature 
 of our birth and marriage statistics is the steadily falling birth- 
 rate and the reduced number of children to each marriage. This 
 is to be deplored, and, if continued, amounts to gradual depopu- 
 lation and the gradual reduction of England and the British Empire 
 to the level of a second-rate Power. It is as much a mistake to 
 suppose that the inhabitants of a country are in proportion to 
 their food, as it is to think that the productions of a country are 
 in proportion to the number of its inhabitants. The truth is, the 
 population that a country sustains does not depend exclusively 
 on the amount of subsistence existing in it at any one time, but 
 rather that the produce of a country is limited chiefly by the 
 character of its inhabitants, and the more civilized and cultured 
 they are, the greater will be the products of their industry. Un- 
 fortunately, population is often out of the place where it is wanted 
 or could be most productive ; but at no time can it be said that 
 the population of these islands is excessive. 
 
 Death-rates. — By the Births and Deaths Registration Act of 
 1874, all deaths must be registered within five days of their 
 occurrence. In 1918, the deaths registered in England and 
 Wales were in a proportion of 17*1 to every 1000 persons living. 
 The death-rate is obtained in exactly the same way as that for births 
 — by multiplying the actual number of deaths from all causes by 
 1000, and dividing the product by the population ; this is known as 
 the general or gross death-rate. In a similar way as explained 
 above for calculating the weekly or quarterly birth-rate, so is the 
 annual death-rate for the week, month, or quarter obtained. 
 
 Thus, take a town with a population of 20,000 and the deaths 
 in any week being 8, the annual death-rate for that week will be 
 2I > or 20000 * 52-17747 x 1000 = 20*87. These so-called 
 weekly death-rates are convenient for reports, but are not reliable 
 data on which to compare the relative conditions of places, as 
 much of the mortality often depends upon epidemics, weather, 
 and other causes of a temporary nature. These death rates, as 
 
DEATH-RATES. 423 
 
 published for each week by the Registrar-General, must there- 
 fore not be regarded as actual rates, but rather as annual rates 
 per 1000, representing the number who would die supposing the 
 same proportion of deaths to population held good all through 
 the year. Their chief value is for contrasting mortality rates of 
 any given place at corresponding periods of some previous year. 
 The value of the general death-rate has been much criticized 
 on the ground that it is much influenced by movements of the 
 populations, by the presence of large institutions, such as hospitals, 
 by the age and sex distribution of the population, and by the 
 birth-rate. All this is quite true, but still, if due correction be 
 made, it is probably, in the case of large populations, the most 
 trustworthy test we have of relative vitality. The corrections most 
 advantageously applied to general death-rates are : (1) for non- 
 resident, or migratory people ; (2) for age and sex distribution. 
 
 The correction for a migratory population is most difficult to 
 apply, as it is not easy to trace and control the facts relating 
 to visitors and immigrants. In the case of watering-places and 
 favourite residential towns, corrections in this direction are most 
 important, and are largely made by the officials from materials 
 obtainable from the sub-registrars; but, even under the best 
 supervision, considerable disturbance and fallacies to the statistics 
 occur. Closely allied to the consideration of migration is the 
 effect which public institutions, such as poor-houses or hospitals, 
 exert on local death-rates, as the disturbance arising from them 
 is due to migration into them from neighbouring districts. To 
 meet this difficulty, the rule is to deduct the deaths of those 
 inmates drawn from outside areas, at the same time adding the 
 deaths of proper inhabitants of the place which may have occurred 
 in other institutions outside the district. Each sanitary authority 
 in London and in every urban and rural district in England is 
 supplied quarterly by the Registrar-General with particulars of 
 death of their inhabitants, so that the deaths in all these cases 
 may be apportioned to their proper districts. All general death- 
 rates require to be corrected for age and sex distribution. 
 Females live longer than males. It follows, therefore, that if two 
 towns were in an equally healthy state, but that one of them con- 
 tained a larger proportion of females than the other, the one with 
 the lower proportion of females would have the higher death-rate. 
 Similarly, there is a great tendency to death among infants ; this 
 liability to die reaching its minimum from between ten to fifteen 
 years of aire, and afterwards steadily increasing throughout life. 
 
 The following table shows the mortality from all causes in 
 England and Wales during 1918 expressed per million. The 
 term "standardized death-rate" means the death-rate corrected 
 for differences of sex and age constitution of the population. 
 
424 
 
 VITAL STATISTICS. 
 
 
 
 
 
 
 
 
 
 
 Males. 
 
 Females. 
 
 Persons. 
 
 
 1918 
 (Civilians only). 
 
 1918. 
 
 . . x 9 l8 
 (Civilians only). 
 
 ah Q „ AC / Crude . . . 
 
 21,098 
 
 15,086 
 
 • 17,560 
 
 Ail ages j Standardized , 
 
 
 
 19,814 
 
 14,642 
 
 17,095 
 
 o- 
 
 3^523 
 
 33,847 
 
 36,201 
 
 5- 
 
 
 
 
 
 
 
 
 5,271 
 
 5,554 
 
 5,412 
 
 10- 
 
 
 
 
 
 
 
 
 3,413 
 
 3,88o 
 
 3,647 
 
 15- 
 
 
 
 
 
 
 
 
 
 ? 
 
 5,964 
 
 ? 
 
 20- 
 
 
 
 
 
 
 
 
 
 ? 
 
 7,691 
 
 ? 
 
 2 5- 
 
 
 
 
 
 
 
 
 
 ? 
 
 9,291 
 
 ? 
 
 35- 
 
 
 
 
 
 
 
 
 
 ? 
 
 8,646 
 
 ? 
 
 15-45 
 
 
 
 
 
 
 
 
 
 14,663 
 
 8,201 
 
 10,176 
 
 45- 
 
 
 
 
 
 
 
 
 
 i6,754 
 
 12,904 
 
 i4,73i 
 
 55- - 
 
 
 
 
 
 
 
 
 
 29,554 
 
 22,893 
 
 26,127 
 
 65- 
 
 
 
 
 
 
 
 
 
 64,652 
 
 49,625 
 
 56,363 
 
 75- ■ 
 
 
 
 
 
 
 
 
 
 139,540 
 
 112,628 
 
 123,319 
 
 85 and upwards 
 
 246,705 
 
 242,691 
 
 244,122 
 
 It follows, therefore, that a tow r n, a large proportion of whose 
 inhabitants were at the most viable age, would have a lower death- 
 rate than a town equally healthy, in which the ages of the people 
 were less favourable to long life ; just as it would be if the one 
 town had a much larger population of females than the other. 
 In order to neutralize these errors, the Registrar-General has 
 devised a method by which they can be corrected. 
 
 This method, based primarily upon the death-rate of each sex 
 at different ages throughout England and Wales, provides a series 
 of factors by which the recorded death-rates of the great towns 
 can be each multiplied so as to make them comparable with that 
 of England and Wales. By the use of these factors, the recorded 
 gross death-rate of any of these towns Can be lowered or raised 
 to what it would be if the age and sex distribution of that par- 
 ticular town were the same as that of England and Wales 
 generally. This new rate is called the corrected death-rate. The 
 factor employed is practically the expression of the ratio which 
 the recorded death-rate bears to an empirical (arbitrary) standard 
 death-rate^ calculated on the hypothesis that deaths at each age 
 period were at the same rate as in England and Wales during the 
 decennium 1896-1905, the death-rate at all ages in England and 
 Wales during that period having been i8'i94 per 1000. Owing 
 to the proportions of persons of low mortality being excessive in 
 most towns, their recorded death-rates are too low, and in con- 
 sequence the factor for their correction is in most cases above 
 unity, the only exceptions being Hastings, Southampton, Ipswich, 
 
DEATH-RATES. 
 
 425 
 
 Brighton, Yarmouth, Norwich, and Plymouth. The table below 
 gives these factors for the chief towns as issued by the Registrar 
 General in 191 2, along with their recorded or crude death-rates 
 per 1000 living in 191 1 : — 
 
 
 S 0* 
 
 Crude 
 
 Corrected 
 
 s.t 
 
 Towns, 
 
 •2 e<.° 
 
 Death 
 
 -rate. 
 
 Death 
 
 •rate. 
 
 *2 .*£ 
 
 in the order of 
 
 
 
 
 
 
 
 their corrected 
 
 
 
 
 
 e-o J* 
 
 Death-rates, 191 1. 
 
 fa «.» 
 
 Average 
 1906-10. 
 
 1911. 
 
 Average 
 1906-10 
 
 1911. 
 
 0<i bJO 
 
 Cols. 
 
 1. 
 
 2. 
 
 3- 
 
 4- 
 
 5. 
 
 6. 
 
 England and Wales . 
 
 i' 0000 
 
 I4-70 
 
 14*60 
 
 M-70 
 
 14-60 
 
 1,000 
 
 England and Wales, less 
 
 9-9637 
 
 I4'02 
 
 13*89 . 
 
 I3-5I 
 
 I3-39 
 
 917 
 
 the 77 Great Towns 
 
 
 
 
 
 
 
 77 Towns 
 
 1*0627 
 
 i5'54 
 
 15*48 
 
 16-51 
 
 16-45 
 
 1,127 
 
 King's Norton 
 
 1-0456 
 
 10*16 
 
 9-09 
 
 10-62 
 
 9*50 
 
 651 
 
 Hornsey 
 
 
 1-1400 
 
 9-56 
 
 9-5 1 
 
 10-90 
 
 IC84 
 
 742 
 
 Handsworth 
 
 
 1*1007 
 
 io*66 
 
 10*29 
 
 n'73 
 
 n-33 
 
 776 
 
 Bournemouth . 
 
 
 1*0566 
 
 I2'20 
 
 11*41 
 
 12-89 
 
 12-06 
 
 826 
 
 Croydon 
 
 
 1*0250 
 
 12*12 
 
 11-83 
 
 12-42 
 
 12*13 
 
 831 
 
 Ipswich 
 
 
 0*9766 
 
 I4-58 
 
 12*46 
 
 14-24 
 
 12*17 
 
 834 
 
 Reading 
 
 
 i'0343 
 
 I2*80 
 
 11*84 
 
 13-24 
 
 12*25 
 
 839 
 
 Walthamstow . 
 
 
 1-0572 
 
 12-18 
 
 ii*6i 
 
 12-88 
 
 12*27 
 
 840 
 
 Leyton .... 
 
 
 1-0285 
 
 11-38 
 
 12*09 
 
 11*70 
 
 12*43 
 
 851 
 
 Willesden . 
 
 
 1-0728 
 
 1 1 • 50 
 
 11*76 
 
 12-34 
 
 12*62 
 
 864 
 
 East Ham . 
 
 
 1*0671 
 
 12*04 
 
 12-13 
 
 12-85 
 
 12-94 
 
 886 
 
 Hastings 
 
 
 0-9616 
 
 13*68 
 
 13-59 
 
 I3-I5 
 
 13*07 
 
 895 
 
 Great Yarmouth 
 
 
 0-9152 
 
 1 5 '44 
 
 14*30 
 
 I4-I3 
 
 13-09 
 
 897 
 
 Coventry . 
 
 
 1*0024 
 
 12*62 
 
 13-12 
 
 1265 
 
 I3'i5 
 
 901 
 
 Norwich 
 
 
 o-954i 
 
 14-96 
 
 I4-I5 
 
 14-27 
 
 i3'5o 
 
 925 
 
 Wallasey . 
 
 
 1 -0940 
 
 12*66 
 
 12*34 
 
 I3-85 
 
 13-50 
 
 925 
 
 Brighton 
 
 
 0-9856 
 
 14*84 
 
 13-75 
 
 14-63 
 
 I3'55 
 
 928 
 
 Northampton . 
 
 
 1 -0397 
 
 12*94 
 
 13-18 
 
 I3-45 
 
 1370 
 
 938 
 
 York 
 
 
 1*0297 
 
 13-68 
 
 I3'39 
 
 14-09 
 
 I3-79 
 
 945 
 
 Devonport . 
 
 
 1 -0486 
 
 13*04 
 
 13-38 
 
 13-67 
 
 14-03 
 
 961 
 
 Tottenham 
 
 
 1-0791 
 
 12*42 
 
 13*10 
 
 13-40 
 
 14*14 
 
 968 
 
 * The Factor for Correction is the figure by which the Crude Death-rate 
 should be multiplied in order to correct for differences of age and sex con- 
 stitution of population. For method of constructing these factors see Annual 
 Summary, 1908, pp. x.-xiii. These Factors being necessarily based upon the 
 constitution of the population as enumerated in 1901, are only approximately 
 applicable to the conditions of 191 1 owing to the changes which must have 
 occurred meanwhile in the constitution of the various populations. 
 
 f The Comparative Mortality Figure represents the corrected Death-rate 
 in each town compared with the death-rate at all ages in England and Wales 
 during 1911, the latter being taken as 1000. 
 
426 
 
 VITAL STATISTICS. 
 
 
 1 S 0*. 
 
 u '*■< bo c 
 
 Crude 
 
 Corrected 
 
 
 Towns, 
 
 <° c<.2 
 
 Death-rate. 
 
 Death-rate. 
 
 'rt^ M 
 
 in the order of 
 
 :tor : 
 :ctio 
 and 
 ibut: 
 
 
 
 
 
 
 their Corrected 
 
 
 
 
 
 c O fa 
 
 Death-rates, 1911. 
 
 rt *-> bJ *j 
 
 Average 
 1906-10. 
 
 191 1. 
 
 Average 
 
 1906-10. 
 
 1911. 
 
 oS 00 
 
 Cols. 
 
 1. 
 
 2. 
 
 3. 
 
 4- 
 
 5- 
 
 6. 
 
 Leicester .... 
 
 1*0671 
 
 I 3 -8o 
 
 13-29 
 
 I4-73 
 
 14*18 
 
 971 
 
 Burton-on-Trent . 
 
 
 1 -0747 
 
 13-46 
 
 13*23 
 
 I4-47 
 
 14-22 
 
 974 
 
 Barrow-in-Furness 
 
 
 1-1364 
 
 13*52 
 
 12-52 
 
 15-36 
 
 14-23 
 
 975 
 
 Newport (Mon.) . 
 
 
 1 '0804 
 
 14-90 
 
 13-35 
 
 16*10 
 
 14-42 
 
 988 
 
 Portsmouth 
 
 
 
 1*0267 
 
 14*06 
 
 14-05 
 
 14*44 
 
 14*43 
 
 988 
 
 Southampton . 
 
 
 
 0*9942 
 
 13-62 
 
 I5 -I 9 
 
 13-54 
 
 i5*io 
 
 1,034 
 
 Cardiff . 
 
 
 
 1*0875 
 
 14*44 
 
 14-02 
 
 15*70 
 
 15*25 
 
 1,045 
 
 Grimsby 
 
 
 
 1 "0709 
 
 14-62 
 
 14-41 
 
 15*66 
 
 I5-43 
 
 i,057 
 
 Derby . 
 
 
 
 1*0778 
 
 13*92 
 
 14-32 
 
 15*00 
 
 I5-43 
 
 1,057 
 
 Bristol . 
 
 
 
 1*0273 
 
 13*86 
 
 15-12 
 
 14-24 
 
 15*53 
 
 1,064 
 
 Smethwick 
 
 
 
 1 '0940 
 
 13-24 
 
 14-26 
 
 14*48 
 
 15*60 
 
 1,068 
 
 London 
 
 
 
 1-0511 
 
 14-88 
 
 15-04 
 
 15-64 
 
 15*81 
 
 1,083 
 
 West Bromwic 
 
 a 
 
 
 i*ooS5 
 
 15-80 
 
 15-76 
 
 I5-93 
 
 15*89 
 
 1,088 
 
 Tynemouth 
 
 
 
 1*0326 
 
 17*20 
 
 i5'43 
 
 17*70 
 
 15-93 
 
 1,091 
 
 Huddersfield 
 
 
 
 1*0728 
 
 i5'34 
 
 15*00 
 
 16*46 
 
 16*09 
 
 1,102 
 
 Wolverhampto 
 
 n 
 
 
 1 "o343 
 
 15-82 
 
 16-36 
 
 16*36 
 
 16*36 
 
 1,121 
 
 Halifax . 
 
 
 
 1 -0836 
 
 15-16 
 
 15-16 
 
 1 6*43 
 
 i6'43 
 
 1,125 
 
 Bradford . 
 
 
 
 1*1053 
 
 15-32 
 
 14-89 
 
 16*93 
 
 16*40 
 
 1,127 
 
 Merthyr Tydfil 
 
 
 
 1 -0603 
 
 18-28 
 
 15-54 
 
 19*38 
 
 16*48 
 
 1,129 
 
 Rhondda . 
 
 
 
 i- 1000 
 
 15-54 
 
 15-03 
 
 17-09 
 
 16-53 
 
 1,132 
 
 Birkenhead 
 
 
 
 1*0658 
 
 15-44 
 
 I5' 6 4 
 
 16*46 
 
 16*67 
 
 1,142 
 
 Warrington 
 
 
 
 1*0772 
 
 16*96 
 
 15-48 
 
 18*27 
 
 i6*68 
 
 1,142 
 
 Rochdale . 
 
 
 
 i- 1060 
 
 16-76 
 
 15-09 
 
 18-54 
 
 16*69 
 
 i,i43 
 
 Plymouth . 
 
 
 
 0-9750 
 
 16-28 
 
 17-16 
 
 15-87 
 
 16-73 
 
 1,146 
 
 Rotherham 
 
 
 
 i'0343 
 
 15-98 
 
 16*25 
 
 i6'53 
 
 16*81 
 
 1,151 
 
 West Ham. 
 
 
 
 1*0695 
 
 15*54 
 
 15*77 
 
 16*62 
 
 16*87 
 
 i,i55 
 
 Nottingham 
 
 
 
 I-Q535 
 
 16-24 
 
 16*06 
 
 17-11 
 
 16*92 
 
 i,i59 
 
 Gateshead . 
 
 
 
 1*0541 
 
 16-14 
 
 16*09 
 
 17-01 
 
 16*96 
 
 1,162 
 
 Stockport . 
 
 
 
 1*0804 
 
 17*12 
 
 15*74 
 
 18-50 
 
 17-01 
 
 1,165 
 
 Hull . . 
 
 
 
 1*0250 
 
 16-10 
 
 16-67 
 
 16*50 
 
 17-09 
 
 1,171 
 
 Aston Manor 
 
 
 
 1*1087 
 
 14*00 
 
 *5-5o 
 
 I5*52 
 
 17-18 
 
 i,i77 
 
 West Hartlepool 
 
 
 1 -0980 
 
 I5'30 
 
 15-65 
 
 16*80 
 
 17-18 
 
 i,i77 
 
 Walsall . . 
 
 
 1-0590 
 
 I5H4 
 
 16*24 
 
 16*35 
 
 17*20 
 
 1,178 
 
 Stockton-on-Tees 
 
 
 1-0486 
 
 16-62 
 
 16-55 
 
 17*43 
 
 17*35 
 
 1,188 
 
 Newcastle-on-Tyn 
 
 e . 
 
 1*0772 
 
 16-50 
 
 i6-ii 
 
 17-77 
 
 17*35 
 
 1,188 
 
 Sheffield . . 
 
 
 1*0778 
 
 16-30 
 
 16-12 
 
 17*57 
 
 17*37 
 
 1,190 
 
 Swansea 
 
 
 
 1 -072s 
 
 16-50 
 
 16-19 
 
 17*70 
 
 17*37 
 
 1,190 
 
 Bury 
 
 
 
 1*1196 
 
 16-02 
 
 15*86 
 
 17*94 
 
 17*76 
 
 1,216 
 
 Leeds . 
 
 
 
 1*0908 
 
 i6*oo 
 
 16-37 
 
 17*45 
 
 17*86 
 
 1,223 
 
 Bolton . 
 
 
 
 1*1308 
 
 15-90 
 
 15-86 
 
 17*98 
 
 I7-93 
 
 1,228 
 
 Birmingham 
 
 
 
 1*0759 
 
 16-62 
 
 16.78 
 
 17*88 
 
 18*05 
 
 1,236 
 
 South Shields 
 
 
 
 1*0584 
 
 17-04 
 
 17-08 
 
 18*04 
 
 iS*o8 
 
 1,238 
 
 Blackburn . 
 
 
 
 1*1308 
 
 16-30 
 
 l6*I2 
 
 i8'43 
 
 18*23 
 
 1,249 
 
 Salford . 
 
 
 
 1*1047 
 
 18-22 
 
 16*65 
 
 20*13 
 
 18-39 
 
 1,260 
 
 Preston . 
 
 
 
 1 '0940 
 
 17-94 
 
 16*86 
 
 19-63 
 
 18-44 
 
 1,263 
 
 See footnote on p. 425. 
 
 t Ibid. 
 
INFANTILE MORTALITY. 
 
 427 
 
 Towns, 
 
 for 
 n for 
 Age 
 on.* 
 
 Crude 
 Death-rate. 
 
 Corrected 
 Death-rate. 
 
 v • 
 
 in the order of 
 
 :tor 
 ctio 
 and 
 ibut 
 
 
 
 
 
 8* 
 
 their Corrected 
 
 
 
 J^ >« 
 
 Death-rates, 1911. 
 
 ra( 
 Corrt 
 Sex 
 Distr 
 
 Average 
 1Q06-10. 
 
 r 11. 
 
 Average 
 1906-10. 
 
 1911. 
 
 6*5 3 
 
 Cols. 
 
 I. 
 
 2. 
 
 3. 
 
 4- 
 
 5. 
 
 6. 
 
 Sunderland . . 
 
 
 1-0314 
 
 i8*6o 
 
 17-95 
 
 I9-I8 
 
 18*51 
 
 1,268 
 
 Manchester 
 
 
 
 
 1*1135 
 
 18*12 
 
 16*99 
 
 20*18 
 
 18*92 
 
 1,296 
 
 Dewsbury . 
 
 
 
 
 1-0993 
 
 17*5° 
 
 17*25 
 
 19*24 
 
 18*96 
 
 1,299 
 
 Bootle . 
 
 
 
 
 1*1013 
 
 17*26 
 
 17*63 
 
 19*01 
 
 19*42 
 
 i,33a 
 
 Wigan . 
 
 
 
 
 1-0973 
 
 18*28 
 
 17-87 
 
 20*06 
 
 19*61 
 
 1,343 
 
 St. Helens . 
 
 
 
 
 I -0836 
 
 17-02 
 
 18*17 
 
 1 8*44 
 
 19*69 
 
 i,349 
 
 Oldham . 
 
 
 
 
 1*1245 
 
 18*62 
 
 17-62. 
 
 20*94 
 
 19-81 
 
 i,357 
 
 Burnley 
 
 
 
 
 1*1273 
 
 17*70 
 
 17*97 
 
 19*95 
 
 2026 
 
 1,388 
 
 Middlesbrough 
 
 
 
 1 0888 
 
 19*74 
 
 19-42 
 
 21*49 
 
 21*14 
 
 i,443 
 
 Liverpool . 
 
 
 
 1*0702 
 
 19-60 
 
 19*96 
 
 2o*9S 
 
 21*36 
 
 1,463 
 
 Stoke-on-Trent 
 
 
 
 1*0791 
 
 18*48 
 
 19-89 
 
 19*94 
 
 21*46 
 
 1,470 
 
 See footnote on p. 425. 
 
 t Ibid. 
 
 If the corrected death-rate in each town be compared with the 
 death-rate at all ages in England and Wales taken as iooo, 
 it gives a number known as the comparative mortality figure, as 
 shown in the last column of the preceding table. These figures 
 may be expressed in another way, by saying that after correction 
 has been made for differences of age and sex distribution, the 
 same number of people that gave iooo deaths in England and 
 Wales in 1911, gave 1223 in Leeds, 971 in Leicester, and 1263 
 in Preston. Or we can say that in 19 n the recorded death-rate 
 for the whole of England and Wales was 14*60 * and the recorded 
 death-rate for Blackburn is 16*12 with its factor for correction as 
 
 ;o8. Then 16*12 x 1*1308 = 18-23 as the corrected death- 
 
 11 
 
 rate for Blackburn and 
 
 18-23 
 14-60 
 
 X iooo = 1249 as its 
 
 figure 
 
 of 
 
 comparative mortality. 
 
 Infantile Mortality. — The calculations of infant and child 
 mortalities demand special remark ; particularly as it is by no 
 means uncommon to find them worked out on the population, or 
 on the number of deaths at all ages. The proper, the most simple, 
 and most accurate way is rather to utilize the birth returns, and 
 calculate out the ratio of deaths of infants under one year to the 
 number of actual births in the latter half of the preceding year and 
 the first half of the current year. The greatest care should be 
 given to child mortality, or the death-rate of those under rive years 
 of age, as it constitutes an important and instructive index of 
 health conditions. In 1918, the proportion of deaths of infants 
 under one year of age to iooo registered births was 97 or 9-3 per 
 
428 
 
 VITAL STATISTICS. 
 
 cent, below the average of the ten preceding years. For London 
 the infantile mortality rate in 19 18 was 108 per 1000 births. 
 The rate differs widely in different counties and towns; the 
 general rule being that the rate is lowest in the purely agricul- 
 tural, and highest in the mining districts, and in those with textile 
 industries. 
 
 County Borough. 
 
 Deaths 
 
 under 
 
 One Year 
 
 per 1, 000 
 Births. 
 
 Total County Boroughs 
 
 Bournemouth 
 
 Canterbury 
 
 Southport 
 
 Oxford 
 
 Worcester 
 
 Exeter 
 
 East Ham 
 
 Hastings . 
 
 Brighton . 
 
 Lincoln . 
 
 Southend-on-Sea 
 
 Eastbourne 
 
 Bath . . 
 
 Reading . 
 
 Portsmouth 
 
 Croydon . 
 
 Gloucester 
 
 Ipswich . 
 
 Chester . 
 
 Wallasey . 
 
 Wakefield 
 
 Newport (Mon.) 
 
 Bristol 
 
 Southampton 
 
 Northampton 
 
 Coventry . 
 
 Swansea . 
 
 Derby 
 
 Plymouth 
 
 Birmingham 
 
 Wolverhampton 
 
 York . 
 
 Great Yarmouth 
 
 Burton-on-Trent 
 
 Warrington . 
 
 Huddersfield. 
 
 Barrow-in-Furness 
 
 Smethwick 
 
 Cardiff 
 
 Bolton 
 
 109 
 
 57 
 58 
 60 
 62 
 64 
 65 
 67 
 72 
 72 
 
 73 
 73 
 74 
 74 
 75 
 76 
 77 
 83 
 83 
 89 
 89 
 90 
 90 
 92 
 92 
 92 
 
 93 
 
 95 
 
 95 
 
 97 
 
 97 
 
 97 
 
 97 
 
 99 
 
 99 
 ioi 
 
 101 
 
 102 
 
 103 
 104 
 106 
 
 County Borough. 
 
 Norwich 
 Manchester . 
 
 Newcastle-on-Tyne 
 Leicester 
 
 Walsall,. . . . 
 Birkenhead . 
 Tynemouth . 
 Salford . 
 
 Preston .... 
 Dewsbury . 
 
 Bury 
 
 West Bromwich 
 Merthyr Tydfil. . 
 Stockport . 
 Stoke-on-Trent 
 Darlington . 
 Blackpool . 
 West Ham . 
 Bootle . . . . 
 Rochdale 
 South Shields . 
 Oldham . . . . 
 Gateshead . 
 Wigan . 
 Nottingham 
 Blackburn . 
 Bradford 
 Dudley . 
 Liverpool . 
 Halifax . 
 Burnley . 
 
 Hull 
 
 St. Helens . . 
 
 Sheffield . . . 
 
 Grimsby 
 
 Carlisle . 
 
 Sunderland . 
 
 Leeds . 
 
 Rotherham . 
 
 Middlesbrough. 
 
 Barnsley 
 
 West Hartlepool . 
 
 Deaths 
 
 under 
 
 One Year 
 
 per 1,0 o 
 
 Births. 
 
 I07 
 I07 
 I08 
 IO9 
 IIO 
 I IO 
 III 
 112 
 112 
 I 12 
 112 
 I 12 
 
 113 
 
 113 
 
 113 
 114 
 
 114 
 
 115 
 117 
 
 119 
 
 1 20 
 
 121 
 
 123 
 
 123 
 123 
 124 
 125 
 
 125 
 120 
 126 
 126 
 127 
 127 
 128 
 I29 
 130 
 131 
 133 
 136 
 I48 
 l62 
 167 
 
INFANTILE MORTALITY. 429 
 
 The chief causes of infantile mortality, common to every 
 locality, are briefly : premature birth, congenital defects, hereditary 
 tendencies, inexperience and neglect of mothers, industrial con- 
 ditions, improper food, and overlaying. 
 
 The table on p. 428 shows the infant mortality per 1000 
 registered births in the County Boroughs of England and Wales 
 in 191 8. From this it will be seen that the highest infantile 
 mortality was in Leeds, Rotherham, Middlesbrough, Barnsley, 
 and West Hartlepool. 
 
 A very frequent source of error in vital statistics is made in 
 calculating the mean death or other rate of two populations or 
 communities ; these are often spoken of as combiiied death-rates. 
 The error usually arises from failing to take into account the 
 proportion which the two populations or groups bear to one 
 another. Thus suppose two towns each contain 30,000 inhabi- 
 tants, and have respectively mortalities of 22 and 16, their mean 
 
 2 2 I T O 
 
 or combined death-rate would be or 19. But suppose 
 
 one of the towns has 42,000 inhabitants and the other 18,000, 
 and have respectively the above mortalities, their combined 
 death-rate will then not be the mean of their two separate death- 
 rates, but as follows : — 
 
 One town of 42,000 people with a death-rate of 22 per 1000 = 924 deaths. 
 „ „ 18,000 „ „ „ 16 „ = 288 ,, 
 
 or 60,000 people give 1212 deaths, 
 
 , 1212 X 1000 " , . , , , 
 
 ana = 20*2, the true combined death-rate per 1000. 
 
 60,000 ' v 
 
 Death-rates are said to be largely influenced by the birth-rate, 
 and by densities of population. With regard to the influence of 
 the birth-rate upon the death-rate much controversy has prevailed. 
 To a great extent this has been unnecessary, and has arisen from 
 a misconception as to the true meaning of the relation between 
 the birth- and death-rates. If we imagine a population in which 
 there has been a high birth-rate for one or more years, it is clear 
 such must contain a larger proportion than usual of young children, 
 and inasmuch as the death-rate of young children is higher than 
 that of all others except the aged, the general death-rate of that 
 population will be raised ; but this condition is to a large extent 
 counterbalanced by the fact that a high birth-rate implies the 
 presence in that particular population of a large proportion of 
 persons of the child-bearing age, that is, of an age-period when 
 the mortality is unusually low. So, again, if the high birth-rate 
 be continued for any length of years, it means not only a large 
 proportion of children and of persons at reproductive ages, but also 
 
430 VITAL STATISTICS. 
 
 of young adults, among whom a low rate of mortality also 
 prevails. 
 
 The real influence of the birth-rate upon the death-rate, there- 
 fore, is not one which can be well expressed as a low birth-rate 
 causing a low death-rate, or a high birth-rate producing a high 
 death-rate, but rather that the average age of a population governs 
 the death-rate, and that the lower the mean age of the living, 
 the lower should be the death-rate, and, by inference, that the 
 death-rate really controls the birth-rate, because the lower it is 
 the more chance is there of there being a large proportion 
 of persons at the child-producing ages. If a high death-rate 
 follows a high birth-rate, it reasonably suggests an excessive 
 infantile mortality ; very often low death-rates and low birth-rates 
 co-exist, but it does not follow that the one is necessarily caused 
 by the other. 
 
 The influence exerted by density of population on mortality 
 and death-rates has long been recognized. The density may be 
 either expressed as so many persons to a square mile or as acres 
 to a person. Farr found that the mortality increases with the 
 density of a population ; not in direct proportion to the density, 
 but as their sixth root ; while, according to Ogle, this influence of 
 the density does not affect the mortality unless there be more 
 than four hundred persons to the square mile. The practice of 
 building back-to-back houses, so prevalent in Yorkshire and 
 Lancashire, and without provision for through ventilation, illus- 
 trates very clearly the evil effects of crowding populations, and 
 has been well sifted by the reports of Barry and Gordon Smith to 
 the Local Government Board in 1888. 
 
 Increased density of population gives rise to filth conditions, to 
 the more rapid spread of infectious diseases, phthisis, accident, 
 and other evil conditions, the outcome of co-existent poverty and 
 occupation. It is probably by and through these, rather than 
 from mere overcrowding, that density of population in any way 
 influences the death-rate of a community. 
 
 Causes of Death. — It is not sufficient to know the death-rate 
 of a community ; it is necessary to know and inquire what rates 
 the different causes of death give when the deaths are distributed 
 to their several classes. Although the death returns obtained 
 from registrars are principally derived from certificates signed by 
 either doctors or coroners, and, as such, should be clear state- 
 ments of the precise cause of death, still even now the cause of 
 death in many cases is both vague and ill-defined. Each year, 
 however, shows improvement in this direction, with the result 
 that the registration of death-causes is becoming gradually more 
 and more accurate and complete. 
 
CAUSES OF DEATH. 43 1 
 
 The death-rate from zymotic or special febrile diseases is an 
 important fact to be noted among all communities, as it furnishes 
 a very popular standard as to their general healthiness. But it 
 will readily be understood that it is liable to great fluctuations 
 according to the greater or less prevalence of one or other of 
 those diseases, with the result that a so-called mean zymotic death- 
 rate is often of little value. Thus, say in a given community the 
 zymotic death-rate be excessive owing to the epidemic prevalence 
 of the two zymotic diseases, measles and whooping-cough. Owing 
 to these diseases not being either usually or truly dependent 
 upon defective sanitary conditions, their excessive prevalence, as 
 evidenced by an increased zymotic death-rate, furnishes less clue 
 as to the health-condition of the community than would an 
 equally high zymotic mortality rate, owing to such diseases as 
 diphtheria or enteric fever, which are more directly the expression 
 of faulty sanitary states. For this reason the aggregate zymotic 
 death-rate has now been abandoned by the Registrar-General. 
 
 Of late years the deaths from zymotic has shown a steady 
 tendency to fall. The following are the death-rates from some 
 of the principal diseases of this class in England and Wales 
 during 191 8, expressed per million persons living : — Enteric 
 fever, 35 for males and 25 for females, or 30 for all persons; 
 from small-pox only two deaths were recorded; measles, 289 for 
 all ages, or 867 for ages under 15 ; scarlet fever, 29 for all ages, 
 or 80 for ages under 15; whooping-cough, 296 at all ages, and 
 893 for ages under 15 ; diphtheria, 143 for all ages, and 418 for 
 ages under 15; tuberculosis of the lungs showed a rate of 1343, 
 or 7*6 per cent, of the death-rate from all causes. 
 
 The influence of age upon mortality rates is very marked in 
 certain diseases. Thus, phthisis or consumption is at its lowest 
 prevalence between the ages of 5 and 12, but increases up 
 to 47 years of age, after which it lessens. Small-pox mortality 
 is highest in the first and twenty-fifth years, while diarrhoea, 
 whooping-cough, measles, and diphtheria all have their highest 
 death-rates during the first few years of life. Cancer is a disease 
 which appears rarely to affect the young, but tends to increase after 
 28 years of age. Diseases connected with the heart and circulatory 
 system increase in their mortality rates from birth upwards. The 
 total death-rate, and the death-rates from affections of the nervous 
 system, lungs, and bladder, all appear to be at their lowest between 
 the tenth and fifteenth years of life. 
 
 Occupation. — Modern investigations have thrown consider- 
 able light upon the influence which occupation has upon 
 mortality. Some callings are much less favourable to health 
 than others ; some again, while being relatively healthy, are 
 
432 
 
 VITAL STATISTICS. 
 
 dangerous. The chief circumstances which render certain em- 
 ployments more or less hurtful to health are, bad ventilation 
 and overcrowding of workrooms ; exposure to weather, or 
 extremes of heat and cold ; inhalations of vapours, gases, or 
 metallic, mineral, or organic dust; overstrain, and mental anxiety; 
 and intemperance. Many difficulties and fallacies underlie all 
 comparative statistics of class mortalities, unless due allowance 
 be made for the age at which such employments are followed, as 
 well as the question of the class of person actually engaged, and 
 the importance of differentiating between employer and employed. 
 The following table shows the comparative mortality amongst 
 persons of various occupations, as gathered from the more recent 
 statistics : — 
 
 
 ive 
 figure. 
 
 
 ive 
 figure. 
 
 
 V 
 u 
 
 3 
 v -I 
 
 Occupation. 
 
 — ■ — 
 
 Occupation. 
 
 
 Occupation. 
 
 '5 ^ 
 
 u • — 
 
 
 Is 
 
 M 
 
 OS 
 
 
 Com pa 
 Mortal 
 
 
 11 
 
 3.2 
 
 u2 
 
 Clergymen . 
 
 5 2 4 
 
 Artists or 
 
 
 Silk workers 
 
 964 
 
 Gardeners 
 
 563 
 
 architects . 
 
 823 
 
 Fishermen . 
 
 967 
 
 Game-keepers 
 
 586 
 
 Coachmaken 
 
 > . 
 
 824 
 
 Law clerks . 
 
 970 
 
 Farmers . 
 
 59<3 
 
 Milk sellers 
 
 
 832 
 
 Other occupied 
 
 
 Railway engine- 
 
 
 Drapers . 
 
 
 845 
 
 males . 
 
 978 
 
 men 
 
 610 
 
 Jewellers 
 
 
 872 
 
 Shoemakers . 
 
 984 
 
 Farm labourers . 
 
 621 
 
 Gasworkers 
 
 
 878 
 
 Wool workers . 
 
 984 
 
 Brick makers 
 
 653 
 
 Coal miners 
 
 
 885 
 
 Commercial 
 
 
 Schoolmasters 
 
 665 
 
 Millers . 
 
 
 89O 
 
 travellers . . 
 
 988 
 
 Civilservice clerks 
 
 723 
 
 Bricklayers, 
 
 
 Printers . 
 
 994 
 
 Grocers . 
 
 729 
 
 Masons 
 
 906 
 
 Druggists 
 
 999 
 
 Paper makers 
 
 730 
 
 Cord makers 
 
 9IO 
 
 Tramway men . 
 
 1013 
 
 Coal merchants . 
 
 73i 
 
 Commercial 
 
 
 Fishmongers 
 
 1013 
 
 Navvies . 
 
 740 
 
 clerks . 
 
 911 
 
 Curriers . 
 
 1015 
 
 Ironmongers . 
 
 74i 
 
 Engine fitters 
 
 913 
 
 Paperhangers 
 
 1018 
 
 Ironstone miners. 
 
 744 
 
 Hosiery makers. 
 
 921 
 
 Tailors . 
 
 1027 
 
 Lawyers . 
 
 750 
 
 Bakers . 
 
 922 
 
 India-rubber 
 
 
 Tallow or soap 
 
 
 Indoor servants. 
 
 927 
 
 workers . 
 
 1032 
 
 makers . 
 
 764 
 
 Stationers 
 
 931 
 
 Copper and tin 
 
 
 Engine dri vers, &c. 
 
 767 
 
 Bookbinders 
 
 934 
 
 smiths 
 
 1043 
 
 Maltsters . 
 
 773 
 
 Blacksmiths . 
 
 937 
 
 Carpet makers . 
 
 1044 
 
 Tanners . 
 
 774 
 
 Stone quarriers . 
 
 939 
 
 Chemical workers 
 
 1065 
 
 Sawyers . 
 
 774 
 
 Greengrocers 
 
 942 
 
 Plumbers,painters 
 
 1114 
 
 Railway clerks . 
 
 776 
 
 Saddlers . 
 
 945 
 
 Cotton workers . 
 
 1114 
 
 Messengers . 
 
 791 
 
 Lace makers 
 
 950 
 
 Dyers, bleachers 
 
 1114 
 
 Cycle makers 
 
 797 
 
 Doctors . 
 
 95 2 
 
 Slaters, tilers 
 
 1IX 5 
 
 Wheelwrights 
 
 808 
 
 Cabinet makers. 
 
 956 
 
 Hatters . 
 
 1 137 
 
 Rlwy. guards, etc. 
 
 813 
 
 Gas or lock titters 
 
 957 
 
 Butchers 
 
 1 148 
 
 Shipwrights . 
 
 817 
 
 Tobacconists 
 
 962 
 
 Carmen . 
 
 1 153 
 
 Carpenters . 
 
 820 
 
 Lithographei 
 
 s . 
 
 964 
 
 Grooms . . 
 
 ii57 
 
OCCUPATION. 
 
 433 
 
 
 aj 
 
 3 
 V -£, 
 
 
 ive 
 figure. 
 
 
 £ 
 
 3 
 V M 
 
 Occupation. 
 
 re iv 
 
 Occupation. 
 
 3* 
 
 Occupation. 
 
 re Z? 
 
 
 E ^ 
 
 o ° 
 
 
 ? 
 
 
 re "Z 
 
 is 
 
 
 Cj£ 
 
 
 u< 
 
 
 OS 
 
 Gunsmiths 
 
 11S1 
 
 Musicians 
 
 1261 
 
 General shop- 
 
 
 Wood turners 
 
 1181 
 
 Scissor or file 
 
 
 keepers 
 
 1548 
 
 Nail or chain 
 
 
 makers 
 
 1315 
 
 Seamen . 
 
 1646 
 
 makers 
 
 1187 
 
 P'urriers . 
 
 1332 
 
 Copper miners . 
 
 1668 
 
 Hairdressers . 
 
 1 196 
 
 Bargemen 
 
 1333 
 
 Inn keepers . 
 
 1781 
 
 Lead miners 
 
 1206 
 
 Chimney sweeps 
 
 1343 
 
 Hotel servants . 
 
 1883 
 
 Brush makers 
 
 1216 
 
 Brewers . 
 
 1393 
 
 Costermongers . 
 
 2007 
 
 Coalheavers . 
 
 1221 
 
 Dock labourers . 
 
 1484 
 
 Tin miners . 
 
 2131 
 
 Glass blowers 
 
 1260 
 
 Potters . 
 
 1493 
 
 General labourers 
 
 2235 
 
 The comparative mortality figures as given in the foregoing 
 table simply mean that, for any given occupation, there would be 
 that number of deaths for every 1000 deaths in the general male 
 population of similar numbers and identical age distribution. 
 
 If comparisons be made with corresponding statistics calculated 
 on the census returns of 1891, it is found that the mortality in the 
 main working period of life has declined by 16 per cent. Nearly 
 all occupations have shared in this decline, for only six grades of 
 workers show an increase of mortality; these are lace makers, 
 hosiery manufacturers, copper miners, tin miners, general shop- 
 keepers, and general labourers. The total number employed in 
 these occupations amounts, however, to less than one-twentieth 
 part of the total occupied male population above the age of 
 15 years. The recorded increase of mortality among lace and 
 hosiery manufacturers is small, being one per cent, among the 
 former and six per cent, among the latter. Among copper miners 
 the increase is 13 per cent., but the number of these workers is 
 inconsiderable. Tin miners are also few in number ; their mor- 
 tality shows an increase of 35 per cent, on the previous record. 
 Among general shopkeepers the increase of mortality amounts to 
 26 per cent., and among general labourers to no less than 41 per 
 cent. It is probable, however, that owing to more accurate state- 
 ments of occupation under each heading the mortality figures in 
 the two periods are hardly comparable ; but, even now, the 
 mortality in both these occupations is above the standard for all 
 occupied males. 
 
 In attempting to judge the health of a community by statistical 
 evidence, the greatest importance is attached to the following 
 
434 VITAL STATISTICS. 
 
 points, namely : The total corrected death-rate, the zymotic death- 
 rate, and the infant mortality. All these have been discussed, 
 and the various sources of error connected with them explained. 
 But, besides these, certain other evidence is usually considered, 
 mainly as a test of the mean or average longevity of the popula- 
 tion. This evidence consists of facts relating to what is known 
 as " the mean age at death," " the probable duration of life," and 
 " the expectation of life." 
 
 The mean age at death is of course obtained by adding up 
 the ages of persons dying, and dividing this sum by the total 
 number of deaths. In this country, the mean age of death 
 averages 42 for males, and 45 for females. This fact is, however, 
 an imperfect and crude test or index of longevity, simply because 
 it is so largely affected by the birth-rate. If the birth-rate be 
 high, there will be in consequence a greater proportion of infants 
 or young children in the population. These we know have a 
 relatively high death-rate, with the result that the average age at 
 death will be proportionately reduced. 
 
 The probable duration of life is practically the age at which 
 exactly half of any given number of children born alive will have 
 died ; or, in other words, there are equal chances of their dying 
 before and after that age. It is sometimes spoken of as the 
 equation of life, or vie probable of French writers. All these terms 
 are more or less unfortunate, as there is a probability for every 
 possible duration of life. Regarded strictly as denned above, 
 the probable duration of life is of no great value as a test of 
 longevity ; it can only be obtained from what is called a life- 
 table, and as so determined for England and Wales, gives the 
 probable duration of life for each male 47 years, and for each 
 female 52 years. The probable duration of life is often con- 
 founded with another statistical expression, called the mean 
 duration of life, which is the probable or likely duration of life 
 from birth, and, by French writers, called the vie moye?uie. If we 
 imagine an absolutely stationary population, that is, one in which 
 age and sex distribution does not change, then, starting from 
 birth, the mean duration of life would be identical with the mean 
 age at death, and with the expectation of life as determined by 
 means of life-tables. But such a stationary population is rare, 
 and in an ordinary community, whose numbers are constantly 
 being disturbed by migration or other causes, the mean duration 
 of life really signifies the present age in years plus the probable 
 duration of life after having attained a given age, and which is 
 more commonly called the mean after lifetime, or expectation of 
 life. For comparative purposes, it is often more convenient to 
 employ the term mean duration of life as indicating the expectation 
 
PROBABLE DURATION OF LIFE. 435 
 
 of life at birth ; but if it is required to remove the disturbing 
 influence of infant mortality, then the mean after lifetime, or 
 expectation of life at a later age, must be taken. This expression, 
 expectation of life, must not be taken to imply that any individual 
 may reasonably expect to live a given number of years, because it 
 has no true relation to the most probable duration of the lifetime 
 of any given person. It merely shows the average number of 
 years which a person, at a given age, lives, and in that sense 
 constitutes the tme measure of the chances of living which a 
 mixed community has. Its estimation is made by means of what 
 is called a Life Table, and which is nothing more than a table 
 constructed from census figures on the basis of the number living 
 and the number dying at each age. Such a table shows how 
 many out of say a million persons supposed to be born at the 
 same time will survive at the end of each year or term of years. 
 The same table will also show the sum of the number of years 
 which they live, and if this sum of these years be divided by the 
 number living at any given age, the result will be the expectation 
 of life for that given age. 
 
 Farr called a life-table a bionieter, because it really represents 
 " a generation of individuals passing through time," and measures 
 the probabilities of life and death of this generation at birth, and 
 of the survivors at each successive age-period, until the whole 
 generation is extinct. In order to construct a life-table, it is 
 necessary to have (i) particulars from a census return of the 
 number, age, and sex-distribution of a population ; (2) return of 
 deaths for one or more years among this same population, grouped 
 in the same ages or age-periods as have been adopted for slating 
 the census population. A separate table is required to be con- 
 structed for each sex, and for this reason the death returns must 
 be distinct for the two sexes. 
 
 A life-table can be constructed for either annual or quin- 
 quennial intervals ; in most tables, an annual interval is adopted 
 for the first five years, and after that five-year periods are taken. 
 The first step is to calculate from the census returns the death- 
 rate per 1000 living for each age or group of ages, and call thi^ 
 D. These deaths may be assumed to be evenly distributed over 
 the whole age-period, so that half the deaths will occur in the 
 first portion of the period, and the other half in the second 
 portion ; and the ratio of the final to the initial population is 
 
 1000 — ^D ... . . ... , , 2000 — D 
 
 — rrr, which, when simplified, becomes r— ^. 
 
 1000 -h^-D 2000 -f D 
 
 For the construction of a hypothetical life-table, let us suppose 
 
 that the mortality among infants in a given population is 100 for 
 
 every 1000. It will be at once evident that if there be r ,000,000 
 
\5 
 
 or 
 
 436 VITAL STATISTICS. 
 
 babies born and living at the commencement of a given year, 
 
 these will be reduced to 900,000 in the course of the year, and 
 
 this number will commence the second year. Presuming that the 
 
 data show that the death-rate among children in the second year 
 
 of life is as high as 50 per thousand living, then applying the fore- 
 
 2000 — 50 1950 
 
 going formula, we get r- — or — — or 0*95 1019, and the 
 
 00 5 2000 + 50 2050 u * 
 
 900,000 children at the beginning of the second year are reduced 
 to 900,000 x 0*951219, or 856,097 at the beginning of the third 
 year. In the same way, knowing the death-rates for the third, 
 fourth, and fifth years of life, the actual numbers of children 
 surviving at the end of those age-periods is calculated. Suppose 
 now, by the end of the fifth year only 650,000 survive out of the 
 original million, and we propose to continue constructing the 
 life-table for quinquennial or five-year periods in place of annual 
 intervals. The calculation is practically the same, substituting 
 for the death-rate of each year the death-rate for each quinquen- 
 nium. Presume the death-rate among persons aged 5 to 10 years 
 to be 7, then applying the formula for the reduction of the 
 
 /2000 — 7V 
 population during this five-year period, we get ( -r— J 
 
 0*965632, and at the end of this quinquennium, or by 
 the end of the tenth year, the 650,000 will be reduced to 
 650,000 X 0*965632 = 627660. This calculation can be re- 
 peated for each five-year period until there are no more 
 survivors left. 
 
 Such an ideal life-table will consist of a series of columns, in 
 the first of which will be entered the various years of life or age- 
 periods headed by the symbol x. 
 
 The second column would be marked D, or as it is sometimes 
 written M^ The entries in this column would be obtained by 
 dividing the deaths during each year or age-period by the 
 corresponding mean population, and represent the rate of 
 mortality. 
 
 From the entries in the second column, those of the third or 
 p x column would be obtained. These represent the probability 
 of living one year for each age or age-period, as calculated from 
 
 the formula p x = — — 
 
 2000 -j- U. 
 
 The next column, l x is obtained by multiplying the number 
 living at the immediately preceding year by p^ The entries in 
 this column will represent the number surviving at each successive 
 age, or, in other words, l x represents the number who reach the 
 precise age x. 
 
 The next column required in a life-table is one showing the 
 
CONSTRUCTION OF LIFE-TABLES. 
 
 437 
 
 mean number living in each year of life, and technically called P^ 
 
 Thus the mean number living in the tenth year = — 
 
 The next column in the table is known as the Q^ column. 
 The number opposite any age in this column is the sum of all 
 the numbers in the P x column from that age to the end of the 
 table, that is, until all the lives become extinct : and it shows, 
 therefore, the aggregate number of years which the persons at 
 each age in the table will live. 
 
 The last column is that marked E^.; in it, opposite each age, 
 is placed the mean after lifetime, or expectation of life at each 
 
 age. This is obtained from the formula E x = -j- 
 
 The following table represents the headings of a typical life- 
 table, prepared in accordance with the foregoing principles; it 
 will serve to show a complete view of the results obtainable from 
 a life-table. Each year of age should be inserted to make it 
 complete, but in order to economize space, the intermediate years 
 have been omitted. 
 
 Age 
 of Age- 
 Period. 
 
 X. 
 
 A nntial ATor- 
 
 Probability 
 
 Number 
 
 Mean 
 
 Years of 
 
 Mean 
 
 . 1 LlllUCAl llli VI 
 
 tality per 
 
 Unit at Age^r. 
 D or M^ 
 
 of Living one 
 Year from 
 each Age 
 
 /V 
 
 Born and 
 Living at 
 each Age. 
 
 Population 
 
 in each Year 
 
 of Age. 
 
 Life Lived at 
 
 Age x and 
 
 upwards. 
 
 afterLife- 
 time at 
 
 each Age 
 x. E x . 
 
 O 
 
 0*18326 
 
 0*83212 
 
 5">745 
 
 456,820 
 
 20,426,138 
 
 39 '4 1 
 
 5 
 
 0*01369 
 
 0*98640 
 
 370,35^ 
 
 367,672 
 
 18,410,252 
 
 49' 7 1 
 
 IO 
 
 0-00563 
 
 0*99438 
 
 353<<>3i 
 
 352,007 
 
 16,608,936 
 
 47'oi 
 
 15 
 
 "005 19 
 
 99482 
 
 3+4,290 
 
 343,415 
 
 14,866,429 
 
 43-18 
 
 20 
 
 0*00832 
 
 0*99171 
 
 333>6oS 
 
 332,231 
 
 13,169,656 
 
 39H8 
 
 25 
 
 O"O092O 
 
 0*99084 
 
 319,442 
 
 317,892 
 
 11,536,677 
 
 36*12 
 
 35 
 
 0*01105 
 
 0*98901 
 
 288,850 
 
 287,229 
 
 8,492,601 
 
 29*40 
 
 45 
 
 001554 
 
 0*98458 
 
 253,708 
 
 251,763 
 
 5,774,489 
 
 22*76 
 
 55 
 
 "0248 5 
 
 0*97644 
 
 209,539 
 
 206,984 
 
 3,447,708 
 
 16 '45 
 
 65 
 
 0*04698 
 
 0*95410 
 
 i5o,754 
 
 147,315 
 
 1,631,508 
 
 10*82 
 
 75 
 
 0*10391 
 
 0*90122 
 
 75,777 
 
 72,012 
 
 491,685 
 
 6*49 
 
 85 
 
 0*21966 
 
 0*80208 
 
 16,877 
 
 15,151 
 
 63,030 
 
 3-73 
 
 95 
 
 0-42035 
 
 0*65265 
 
 833 
 
 678 
 
 1,806 
 
 2*17 
 
 105 
 
 
 
 4 
 
 n 
 
 
 
 5 
 
 """""™* 
 
 On this basis a number of life-tables have been constructed, 
 the earliest being based on the population of England and Wales 
 enumerated in 1841, and the deaths registered in the seven years 
 1838-44. The latest life-table for England and Wales is that 
 issued from the Registrar-General's office by Tatham, and based 
 on the death-rates 'for the ten years 1891-1900, and on the census 
 
438 
 
 VITAL STATISTICS. 
 
 returns of 190 1. The following table gives a portion of this life- 
 table as issued in 1907 : — 
 
 Age. 
 
 x, 
 
 o 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 10 
 
 15 
 
 20 
 
 25 
 
 30 
 
 35 
 40 
 
 45 
 50 
 
 55 
 60 
 
 65 
 
 70 
 
 75 
 80 
 
 85 
 90 
 
 95 
 100 
 
 Chance of Living 
 
 One Year from 
 
 each Age. 
 
 
 0*82814 
 0*94681 
 
 0-97917 
 0-98682 
 0-99030 
 0-99282 
 0-99786 
 0-99695 
 
 o-99543 
 0-99432 
 
 0-99329 
 
 0-99103 
 
 0*98810 
 
 0-98519 
 0-98064 
 0-97432 
 0-96404 
 0-95031 
 0*92788 
 0*89460 
 0*84800 
 07S642 
 070S14 
 0*61719 
 0*52092 
 
 H 
 
 0*85934 
 0-9505I 
 0-97986 
 0-98666 
 0*99045 
 0*99294 
 0-99769 
 
 0-99694 
 0-99586 
 0-99498 
 0-99382 
 0*99218 
 0-99005 
 0-98830 
 0-98505 
 
 0-97977 
 0-97072 
 0*95813 
 0-93757 
 0-90689 
 0-86374 
 0-80655 
 0-73622 
 0-65806 
 0-58305 
 
 Of 
 
 1,000,000 
 
 Males 
 
 born, the 
 
 Number 
 
 Surviving 
 
 at each 
 
 Age. 
 
 
 1,000,000 
 828,136 
 784,090 
 
 7 6 7,754 
 757,631 
 750,281 
 
 734,299 
 725»373 
 7H,7H 
 693, 8 94 
 673,200 
 648,169 
 
 615,964 
 577,010 
 530,888 
 
 475,849 
 409,518 
 
 332,344 
 246,630 
 
 158,608 
 82,298 
 
 3I.323 
 
 7,724 
 1,059 
 
 138 
 
 Of 
 
 1,000,000 
 
 Females 
 
 born, the 
 
 Number 
 
 Surviving 
 
 at each 
 
 Age. 
 
 1,000,000 
 
 859,342 
 8l6,8lO 
 800,357 
 789,683 
 
 782,144 
 765,267 
 
 755,499 
 741,766 
 725,386 
 
 705,819 
 682,147 
 
 653> OI 4 
 619,184 
 580,320 
 
 533,io5 
 473,037 
 398,299 
 309,168 
 
 210,688 
 118,068 
 
 49,925 
 i4,33o 
 
 2,494 
 556 
 
 Of 1,000,000 of both 
 
 Sexes born (508,770 
 
 Males and 491,230 
 
 Females). 
 
 The 
 
 Number 
 
 Surviving 
 
 at each 
 
 Age. 
 
 1,000,000 
 843,464 
 800,163 
 
 783,769 
 773,376 
 765,932 
 
 749,5^ 
 740,172 
 
 726,427 
 
 709,363 
 689,223 
 
 664,860 
 
 634,164 
 
 597,727 
 555,170 
 
 503,975 
 440,720 
 
 364,743 
 
 277,251 
 
 184,191 
 
 99,870 
 
 40,461 
 
 10,969 
 
 1,764 
 
 242 
 
 Population 
 or Years of 
 Life Lived, 
 in and above 
 each Year. 
 
 45,920,642 
 45,019,089 
 
 44,197,275 
 
 43,405,309 
 42,626,737 
 
 41,857,083 
 
 38,077,372 
 
 34,352,172 
 
 30,683,582 
 
 27,092,709 
 
 23,595>o47 
 20,207,596 
 16,957,225 
 13,875,672 
 10,990,312 
 
 8,338,589 
 5,971,126 
 
 3,952,986 
 
 2,343,547 
 1,189,793 
 
 486,744 
 148,098 
 
 30,369 
 
 3,784 
 
 573 
 
 Mean after 
 
 Lifetime or 
 
 Expectation 
 
 of Life. E^. 
 
 (A 
 
 44" 1 3 
 52*22 
 
 54*12 
 
 54*26 
 
 53'98 
 
 53'5o 
 
 49*63 
 45*21 
 
 41*02 
 
 37*01 
 
 33'o7 
 29*26 
 25*64 
 
 22*20 
 189O 
 
 15*79 
 12*93 
 
 10*34 
 
 8-05 
 
 6*15 
 
 4-62 
 
 3*45 
 2-58 
 
 i*95 
 i*5i 
 
 I/! 
 V 
 
 E 
 
 u 
 
 is. 
 
 47*77 
 54*53 
 56-34 
 56-49 
 56*25 
 
 5579 
 5i'97 
 47-6i 
 
 43-44 
 39-37 
 35-39 
 31-52 
 27-82 
 24-20 
 20-64 
 17*24 
 14*10 
 11*27 
 8*78 
 6*70 
 
 5-05 
 3*80 
 
 2-87 
 
 2*23 
 
 i-8i 
 
 Having stated the data on which a life-table is based, and 
 described the method of its construction, we are in a position 
 to study the life-history of the persons to which it has refer- 
 ence. The essential points for such a study are the three 
 
 following : — 
 
 (a) The probability of living a given period for each age-period 'in 
 the two sexes separately. This is commonly written/,., and equals, 
 
 number of survivors at end of period 
 as we have already seen, number living at beginning of period" 
 
CONSTRUCTION OF LIFE-TABLES. 439 
 
 Thus, by the above latest English life- table, at birth the proba- 
 bility of a male child living one year is — — . or, the certainty 
 
 1,000,000 J 
 
 of surviving to the end of the first year of life being taken 
 as unity, the probability of his dying during the year is 
 
 1,000,000 — 828,136 
 
 = 0*271864. At 25, the probability of a 
 
 1,000,000 
 
 male living five years by the same life-table is , ' — , 
 
 693,894 
 
 and the probability of his dying during the quinquennium is 
 
 693» 8 94-673> 20 ° . Q -, 
 
 7 5 or o 02982 : and so on. 
 
 693,894 y > 
 
 (b) The number of swvivors out of 1,000,000 children born of 
 each sex, at each succeeding year, or quinquennial period of life, 
 until the whole number becomes extinct by death. The above 
 table starts with a million boys and a million girls assumed to be 
 born at the same time, and shows how many survivors there 
 would be at each successive period. Thus, of 1,000,000 males 
 born, 530,888 are still alive at the end of fifty years from birth ; 
 and of 1,000,000 females born, 580,320 survive to the same age. 
 
 (c) The expectation of life, or mean after lifetime, of males 
 and females at the end of each given period. To find the 
 expectation of life at any age x, the rule is, add together the 
 years of life lived through by the whole of the life-table 
 population after that age, and divide by the number of survivors 
 
 at that age, or E* = -f. Suppose it is required to find the 
 
 expectation of life for males at the age of 35, on the basis of this 
 English life-table. If we refer to that table, and add together 
 the numbers surviving at each age later than 35, we obtain the 
 figure 3,469,353, which is the number of complete five-year 
 periods lived through by the whole of the life-table population 
 after 35 years of age. These five-year periods equal 17,346,765 
 years, and as this number of years is lived by 648,169 males, the 
 number of complete years lived by each male is 2676 years. 
 This result is known as the " curtate expectation of life." 
 
 In the above remarks w T e have confined our attention to the 
 complete quinquennia of life, and have not taken into account 
 that portion of lifetime lived by each person in the quinquennium 
 of his death. In some instances this may be only a few months 
 or days, in others one or more years ; but it may be assumed 
 with a fair degree of accuracy, taking one person with another, 
 that the duration of life in the quinquennium of death will be 
 half such a period, that is, 2*5 years. If we add this 2$ to 
 
440 VITAL STATISTICS. 
 
 the curtate expectation of life, the complete expectation of 
 life is obtained. Thus, the complete expectation for males at 
 35 = 26*76 -f- 2'5 = 29*26 years. In life-tables where the age- 
 periods are given in single years of life, the addition to be 
 made to the curtate expectation will be 0*5 year. Usually, 
 only the complete expectation of life is given in life-tables. 
 
 Recent statistical returns indicate that the expectation of life 
 at birth has risen in the case of males to 51 years, and in 
 that of females to 55 years. These increases are due largely to 
 the lessened mortality in the first few years of life. The increased 
 expectation of life at birth has risen by as much as ten years in 
 the last generation, for both sexes. 
 
 Tests of Longevity. — These resolve themselves practically 
 into attempts to measure the duration of life. The expectation of 
 life or mean after lifetime has been explained and is identical with 
 the " mean duration of life at birth," but the mean duration of life 
 for any later age signifies the age in question plus the mean after 
 lifetime at that age. In the absence of life-tables, the late Dr. 
 Farr showed that the mean duration of life, or mean after lifetime, 
 could be approximately calculated from the birth- and death-rates 
 by the following formula, in which B = birth-rate and D = death- 
 rate, while x = the expectation of life at birth. 
 
 2 1000 , 1 ] 000 
 
 3 D 3 B 
 
 Say a town has a birth-rate of 32 and a death-rate of 28 per 
 1000, then, applying this formula, we get 
 
 2000 1000 2000 1000 
 
 Id + 7F or ~W + ~W = 34 
 
 as the mean expectation of life at birth under those conditions. 
 Willich gives another formula, in which x = the expectation of 
 
 2 
 life at any age a, between 25 and 75 years ; then : x = - (So — a), 
 
 and applying this, say for calculating the expectation of life at 53 
 
 2 
 years of age, we get - (80 — 53) = x, or 18 years. 
 
 For comparative purposes, it is often more convenient to 
 employ the term " mean duration of life " as indicating the 
 expectation of life at birth ; but if it is required to remove the 
 disturbing influence of infant mortality, then the mean after life- 
 time, or expectation of life at a later age, must be taken. This 
 expression, " expectation of life," must not be taken to imply that 
 any individual may reasonably expect to live a given number of 
 years, because it has no true relation to the most probable 
 duration of the lifetime of any given person. It merely shows 
 
VALUE OF STATISTICAL FACTS. 441 
 
 the average number of years which a person, at a given age, 
 lives, and in that sense constitutes the true measure of the 
 chances of living which a mixed community has. 
 
 The mean age of the livings obtained by dividing the sum of 
 the ages of the population at the census by the number of the 
 population, has been proposed as a test of longevity. At best 
 it is unreliable and, as Newsholme says, in insanitary areas the 
 mortality may spend itself chiefly among young children ; apart 
 from this, immigration is a circumstance which especially disturbs 
 the mean age of the living and renders it most untrustworthy as 
 an index of longevity. 
 
 Value of Statistical Facts. — We have now discussed the 
 chief kinds of statistical material generally at the disposal of the 
 sanitarian, but before closing the subject, it is necessary to 
 indicate the chief sources of fallacy in statistics, and the general 
 limits within which they may be used. In an ideal mass of 
 statistics, the facts must (1) be all correctly observed; (2) they 
 must be of the same kind and order ; (3) they must be all 
 localized both in regard to time and place ; (4) they must be 
 sufficiently numerous to give correct averages, and extend over 
 sufficient length of time. It will be at once obvious that these 
 various essentials are not easy to obtain. It has already been 
 explained that while it is easy enough to ascertain correctly the 
 numbers of a people during a census year, it is less simple to 
 do so during intermediate years. Similarly, differences of degree 
 or intensity, causation or virulence of diseases, render their com- 
 parison, by reducing their statistics to the same order and kind, 
 extremely difficult. So, too, the importance of localizing statistics, 
 both in respect of time and place, is made clear by pointing out 
 the absurdity of attempting to construct a particular disease-rate 
 for some health resort from the deaths of persons occurring there 
 from that special affection. The fourth essential for an ideal 
 statistical series is well expressed in the mathematical statement 
 that the error diminishes as the square root of the number of 
 observations ; in other words, the smaller the total number of 
 facts, the larger will be the relative percentage of errors displayed 
 by them, and the larger the number of facts collected the smaller 
 will be the margin of error. 
 
 The i?iean or average has been described as being a number 
 
 which lies between the highest and lowest of a series of numbers, 
 
 and has a definite dependence upon the whole of the series. The 
 
 terms mean and average are often used synonymously ; regarded 
 
 mathematically, there are several kinds of means. Thus, the 
 
 simple average, or arithmetic mean of four numbers, such as 
 
 a -f- b -\- c 4* d 
 a, d, c, d t is conveniently written as , but their 
 
442 VITAL STATISTICS. 
 
 geometric mean would be V abed, while their harmonic mean 
 
 stands thus : — . — , and their quadratic mean is — 
 
 i i i i 
 
 a + ~o + ~c~ + d 
 
 v 
 
 a 2 4- o 2 + £* + d % 
 
 Of course if the terms of the series of numbers are unequal, 
 then the quadratic mean will be the highest, next the arithmetic, 
 and then the geometric and harmonic means ; but if all the terms 
 of the series are equal, then their means are equal too. The chief 
 practical question in vital statistics is not so much the value of a 
 true average, or arithmetic mean, or even the probable value of a 
 fixed quantity, but rather the value of a variable quantity. If we 
 consider any measurable character in a group of people, we find 
 that there is variation, and the first essential is some means of 
 describing this variability. For this purpose, biometricians use the 
 standard deviation, a function usually expressed by the symbol <r. 
 
 Mathematically, standard deviation can be defined by the 
 
 . /n x a? + n 2 a 2 2 + ?i z a z 2 + n A a? 
 following expression, <r = \/ r^ . . . ; 
 
 in which n u n 2 , etc., are the numbers of individuals having the same 
 measurements, and a lt a 2 , etc., are the number of* units separating 
 each group value from the mean value of the whole sample N. 
 Suppose in a sample of ioo poppy capsules 15 individuals had 
 5 stigmatic bands, 30 had 6, 30 had 7, 20 had 4, and 5 had 3, 
 then the arithmetic mean of the whole would be 5*6 stigmatic 
 bands, and the standard deviation would be 
 
 ' 15 (o-6) a + 30 (o-4) 2 + 30 (i-4) 2 + 20 (r6) 2 + 5 (*W 
 ~ v 100 
 
 or V 1 '54 = 1 "24. 
 
 The standard deviation is a concrete number which measures 
 the way the frequencies are distributed in terms of the unit of 
 measurement. Since the greater is the distance between any 
 group value and the mean, the larger is the number by which the 
 total of individuals in the group is multiplied, the standard devia- 
 tion affords us a knowledge as to how the observations are dis- 
 tributed about the mean ; the more they are scattered the larger 
 will be the standard deviation. 
 
 Probable Error. — The theory of the probable error and its 
 connection with the standard deviation is developed from the 
 normal curve of error, and gives that value (p) of x which divides 
 the part of the normal curve representing positive errors into two 
 
PROBABLE ERROR. 443 
 
 equal portions. Its proof is, however, of a complicated nature, 
 and unsuitable for insertion in the present work, 
 
 It is clear that the magnitude of the probable error is a 
 criterion of the weight to be attached to any statistical constant, 
 and any statistical constants unaccompanied by their probable 
 errors are of no scientific importance. Since the exact degree of 
 improbability to be regarded as decisive is a matter of individual 
 opinion, the general rule followed by statisticians when con- 
 sidering probable errors is that unless a result exceeds the 
 expected by two or three times the probable error it is not safe 
 to assume that the particular case differs from the expected 
 result. This value is of considerable use in statistical work, and 
 it may be of interest to see its application to an example or so. 
 Assume a simple case wherein it is wished to find the probable 
 error of an event happening mp times when m trials are made and 
 / is the probability of the event happening and q of its failing. 
 The standard deviation is *I vipq, and the probable error is 
 0*67449 V mpq. Take another case: If 51,350 out of 100,000 
 children proved to be males in a certain township, would it be 
 safe to base on the statistics any theory connected with the 
 variation from the usual probability that the usual number of 
 male children born is to the number of females born as 1050 is to 
 1000? Clearly the expected result is 51,220; therefore the 
 
 probable error is 0*67449*/ 100,000 — 5- . _z2 — r ± 103*9. 
 
 V 2050 2050 
 
 The difference between the actual case and the expected result 
 was 130, and as this is but one and a quarter times the probable 
 error, no definite conclusions can be based on the divergence from 
 the result. Had the number of cases been ten million, then 
 the probable error would have been 1039 and the actual differ- 
 ence 13,000. This would have been sufficient evidence for the 
 conclusion that the ratio 1050 to 1000 did not fit the particular 
 case. 
 
 It is unnecessary here to go into further detail as to the 
 calculation of probable errors. Formulae have been obtained 
 for the errors of all important constants, among which may 
 be mentioned the following : The probable error of the mean is 
 
 standard deviation _ , , , 
 
 ± 0*67449 X — -f-r r c ^~r~ • The probable 
 
 ' ^ y square root of the number of vanates * 
 
 error of the median is + 0*84535 X standard deviation -f square 
 
 root of the number of variates. The probable difference between two 
 
 averages of which the probable errors are known is the square 
 
 root of the sum of the squared probable errors. The p7-obable 
 
 error of the standard deviation is 
 
444 SANITARY LAW. 
 
 square root of twice the number of variates 
 
 ± 0-67449 
 
 standard deviation 
 
 Recognizing that the probable error is a pair of values lying 
 one above and the other below the value determined, we can say 
 that there is an even chance that the true value lies between these 
 limits. 
 
 CHAPTER XII. 
 
 SANITARY LAW, 
 
 It is not proposed in the following pages to completely review 
 and summarize the whole of the law bearing upon the Public 
 Health, but only to consider so much of it as appears requisite 
 to be known by the head of a household. While the main basis 
 of so-called sanitary law, as now in force in the different parts of 
 the United Kingdom, are the various Public Health Acts, notably 
 those of 1867 (Scotland), of 1875 (England and Wales), of 1878 
 (Ireland), and of 1891 and 1899 (London), there are in addition 
 a large number of other Acts of Parliament which, in various 
 ways, strengthen ot otherwise modify the foregoing. This con- 
 dition of affairs naturally renders the whole subject of sanitary 
 law a matter of some complexity. 
 
 For the purposes of this chapter, in place of analyzing each 
 Act separately, we have deemed it more convenient to consider 
 the general effect of legislation as a whole upon certain matters 
 of sanitary importance, and to limit that summary to the law as 
 applicable to England, Wales, and London. 
 
 By the Ministry of Health Act, 1919, a Ministry of Health 
 came into existence, and it has all the powers and duties of the 
 old Local Government Board, of the Insurance Commissioners, 
 of the Board of Education with respect to the health of expectant 
 mothers, of nursing mothers and children under five years of age, 
 and as to the medical inspection and treatment of children and 
 young persons, of the Privy Council in respect of the Midwives 
 Acts, 1902 and 191 8, &nl as to infant life protection under the 
 Children's Act, 1908. 
 
 In order to economize space, certain abbreviations will be 
 employed ; these and the full titles of the chief Acts of Parlia- 
 ment bearing upon the Public Health, and referred to in the 
 following abstract, are given below : — 
 
LOCAL SANITARY AREAS AND AUTHORITIES. 445 
 
 B.A. Board of Agriculture. 
 
 B.M.A. Butter and Margarine Act, 1907. 
 
 C.B.A. Canal Boats Acts, 1877-84. 
 
 CD. (Animals) A. Contagious Diseases (Animals) Acts, 1878 and 1886. 
 
 C.P.A. Cleansing of Persons Act, 1897. 
 
 D.C.M.O. Dairy, Cowshed, and Milk-shop Orders, 1885-86 and 1899. 
 
 F.W.A. Factories and Workshops Acts, 1878, 1895, I 9 OI > an d 1907. 
 
 H.T.P.A. House, Town Planning Acts, 1909 and 1919. 
 
 H W.C.A. Housing of the Working Classes Acts, 1885, 1890, 1900, and 
 
 1903. 
 I. D.N. A. Infectious Disease Notification Act, 1889. 
 I.D.P.A. Infectious Disease Prevention Act, 1890. 
 I.H.A. Isolation Hospital Acts, 1893 and 1901. 
 L.B.A. London Building Act, 1894. 
 
 L.C.C. (G.P.) A. London County Council (General Powers) Act, 1890. 
 L.G.A. Local Government Acts, 1888, 1894, and 1899. 
 M.H. Ministry of Health. 
 M.A. Margarine Act, 1887. 
 M.D.A. Milk and Dairies Acts, 1915 and 1920. 
 M.M.A. Metropolitan Management Act, 1855. 
 M.O.H. Medical Officer of Health. 
 M.S. A. Merchant Shipping Act, 1894. 
 M.W.A. Metropolitan Water Acts, 1852 and 1871. 
 N.B.A. Notification of Births Act, 1907, and Extension Act, 1915. 
 N.I.A. National Insurance Act, 191 1. 
 O.S.A. Open Spaces Act, 1887. 
 
 P.H.A., 1875 and 1896. Public Health Act (England). 
 P.H. (Amend.) A. Public Health Act Amendment Act, 1890. 
 P.H. (Lond.) Public Health (London) Act, 1891. 
 P.H. (Fruit-pickers) A. Public Health (Fruit-pickers) Act, 1882. 
 P.H. (Foods) A. Public Health Food Regulations Act, 1907. 
 P.H. (Interments) A. Public Health (Interments) Act, 1879. 
 P.H.P.A. Public Health Ports Act, 1896. 
 P.H. (Water) A. Public Health (Water) Act, 1878. 
 P.H. (S.) A. Public Health (Scotland) Act, 1867. 
 P.H. (I.) A. Public Health (Ireland) Act, 1878. 
 R.P.P.A. Rivers Pollution Prevention Acts, 1876 and 1893. 
 S.A. Sanitary Authority. 
 
 S.F.D.A. Sale of Food and Drugs Acts, 1875 and 1907. 
 S.F.D. (B.) A. Sale of Food and Drugs Act, 1899. ' 
 V.D.A. Venereal Diseases Act, 191 7. 
 
 Of these Acts, the Public Health Amendment Act, 1890, and 
 the I.D.P.A. of 1890, and the Notification of Births Act, 1907, 
 are alone " adoptive " at the discretion of a sanitary authority. 
 
 Local Sanitary Areas and Authorities. — The whole of Eng- 
 land and Wales, outside the City of London, is divided into (a) 
 administrative counties and {b) county boroughs. By the L.G.A., 
 1894, the administrative counties are divided into county districts, 
 some of which are urban and others rural districts. For sanitary 
 administration, the county boroughs and municipal boroughs are 
 deemed to be urban districts, and constitute urban sanitary dis 
 
446 SANITARY LAW. 
 
 tricts ; while the rural districts, each consisting of one or more 
 parishes, are rural sanitary districts. 
 
 In every administrative county there is a county council, 
 who may appoint one or more Medical Officers of Health, and 
 who have various other powers and duties in connection with the 
 sanitary administration and supervision of the county, more par- 
 ticularly of complaining under sec. 299 P.H.A., 1875, in cases 
 where a S.A. is not doing its duty, and of enforcing the provisions 
 of the Rivers Pollution Prevention Act, the Isolation Hospitals 
 Acts, the Diseases of Animals Act, etc. 
 
 In county and other boroughs the mayor, aldermen, and 
 burgesses, acting as the municipal council, are the urban sanitary 
 authority. In urban districts, other than county and municipal 
 boroughs, the district council constitutes the sanitary authority : 
 but they may appoint committees, consisting either wholly or 
 partly of their members, for the exercise of sanitary powers. An 
 U.D.C. administers the P.H.A., 1875, the P.H.A. (Amend.) A., 
 1890, the P.H. (Water) A., 1878, if applied by the M.H., the 
 R.P. Prev. A., the Factory Act, Housing of Working Classes 
 Acts, the Inf. D.N. A:ts, the Inf. Dis. Prev. Act, 1890 (if adopted), 
 the S.F.D.A., the Horseflesh Act, the Margarine Act, the D.C.M. 
 Orders, the Canal Boats Act, Infant Life Protection Act and 
 Local Acts. 
 
 A rural district council has all the powers, duties, and liabili- 
 ties of an urban sanitary authority under the P.H.A. and other 
 Acts. Ifi addition, the M.H. may, by Order, direct that any 
 provisions of any Act which are applicable to urban districts only, 
 shall apply to rural districts as well. Under this category come 
 various clauses in the P.H. (Amend.) A and the H.W.C.A. The 
 P.H. (Water) A. applies only to rural sanitary districts. A rural 
 district council may apply to the M.H. to have all the powers of 
 an urban district council conferred upon them. 
 
 While in the provinces there is practically one S.A. acting for 
 each district, it is otherwise in the Metropolis. Under L.G.A., 
 1899, with the exception of the City of London, every part of the 
 administrative County of London is situated in some one of the 
 metropolitan boroughs established under the Act. In the City 
 and Port of London the City Corporation are the S.A. In the 
 metropolitan boroughs the borough councils are the S.A., certain 
 powers being transferred from the County Council. These powers 
 can only be exercised within the borough, and refer chiefly to the 
 registration of dairymen, to the removal of obstructions, and sky 
 signs, etc. While certain powers of the County Council will also 
 be exercised by the borough councils. 
 
 Definitions. — There are certain definitions of terms in the 
 
DEFINITIONS. 447 
 
 various sanitary Acts which give to those terms meanings which 
 are not the same as the common meaning. The more important 
 of these definitions are the following : — 
 
 Building. This word includes wooden structures on wheels, 
 also those without foundations, but resting simply on the ground. 
 Under I. D.N. A., 1889, the term "building" applies to boats, 
 vessels, ships, tents, vans, sheds, and other similar structures 
 used for human habitation. 
 
 House. Though not absolutely defined, the term " house " is 
 so extended as to include schools, factories, and other buildings 
 in which persons are employed. For a structure to be a " house " 
 it is not necessary that persons reside in it. 
 
 Under the Town Planning Act, 1909, "house" includes part 
 of a house, and a house does not cease to be a dwelling when no 
 longer inhabited. A " dwelling " is a place in which a person 
 passes the night. 
 
 Owner. Under the Public Health Acts, the term " owner " 
 means the person who, for the time being, receives the rack-rent 
 of the lands or premises in connection with which the word is used, 
 whether on his own account, or as agent or trustee for any other 
 person, or who would so receive the same if such premises were 
 let at rack-rent. By " rack-rent " is meant the rent that is not 
 less than two-thirds of the full net annual value of the property. 
 
 Under Part II. Housing of the Working Classes Act, the 
 owner of a property is held to be any person or corporation who 
 has at least a twenty-one years' interest in it. 
 
 Drain means any drain of. and used for the drainage of, one 
 building only, or premises within the same curtilage, and made 
 merely for communicating therefrom with a cesspool, or like 
 receptacle for drainage, or with a sewer into which the drainage 
 of two or more buildings or premises occupied by different persons 
 is conveyed. 
 
 Sewers include sewers and drains of every description, except 
 drains to which the word •' drain," as above defined, applies. In 
 other words, a sewer is a drain receiving the drainage of two or 
 more buildings, and may be an open channel, such as a polluted 
 watercourse, as well as an underground culvert. The situation 
 has been complicated by certain judicial rulings and interpreta- 
 tions of the adoptive P.H. (Amend.) A., 1890, which imply that, 
 under sec. 19 of this adoptive act, the common pipe is to be 
 deemed a sewer only if ail the houses belong to one owner and 
 that, if they belong to more than one owner, then the combined 
 drain is a drain repairable at the owners' expense, and not a 
 sewer repairable at the expense of the S.A. Fig. 80 will explain 
 the meaning of these definitions. The diagram represents four 
 
448 
 
 SANITARY LAW. 
 
 houses, the drains of which pass out at the back of each into the 
 garden or yard. Under the definition as given in sec. 4 of 
 P.H.A., 1875, the pipe AD is a drain only as far as its junction 
 with the pipe from the second house, after which it is a sewer, as 
 much as the public sewers EF and GF. The application of 
 rhe rulings under sec. 19 of the Act of 1S90, will be obvious, 
 according as to whether the houses are owned by one or more 
 owners. The sec. 19 of the adoptive Act of 1890 speaks of a 
 
 -^ 
 
 STK££T SffVf/? 
 
 
 
 Fig. 80. — Diagram illustrating what is a " drain " and what is a " sewer." 
 
 " single^ private drain," and the whole difficulty seems to hinge on 
 what this expression really means, when read in conjunction with 
 the definition of the words " drain " and " sewer " as contained in 
 sec. 4 of the Act of 1875. 
 
 Our own view of the case is that the majority of the 
 rulings have been wrong, owing to too much importance having 
 been attached to the mere definitions as given in sec. 4 P.H.A., 
 1875, and sufficient attention not having been given to the 
 Act as a whole, especially when read in conjunction with the 
 Amending Act of 1890. To understand the point it is desirable 
 to appreciate the general nature of the drainage system which 
 the 1875 Act designed to establish. By sec. 21 of the Act, an 
 
DEFINITIONS. 449 
 
 owner or occupier is, under certain conditions, entitled to cause 
 his drains to empty into the sewers of the S.A., and by sec. 23 
 that body may require the owner or occupier of any house within 
 its district which is without a drain " sufficient for efficient 
 drainage," to make a covered drain or drains to open into a 
 public sewer, if within 100 feet of the site of such house, or to 
 empty such drain into such covered cesspools or places as the 
 S.A. may direct. Again, under sec. 25 of the Act, it is unlawful 
 in any urban district to erect any house or rebuild any house, or 
 to occupy such newly erected or rebuilt house until covered drains 
 be constructed in such manner as the S.A. approves. Next, we 
 find sec. 40 of the Act of 1875 enacting that these drains must be 
 constructed and kept so as not to be a nuisance, and sec. 41 
 prescribes the machinery by which the owners of houses may be 
 compelled to discharge the obligations imposed on them as 
 regards drains. It is clear from these sections that so long as 
 the drainage was efficient, it was immaterial whether the owner of 
 two or more houses caused the drainage to go into sewer or cess- 
 pool by separate pipes or by several pipes uniting into one. This 
 conduit or conduits would be in the ordinary meaning of language 
 a drain, and, being situate in whole or in part on the premises of 
 the person who constructed, would be " single " and " private " ; 
 and, even if not made to carry off drainage of his own houses, 
 would belong to his premises and consequently to be kept in good 
 order by him. In the case of two or more owners providing for 
 the drainage of their houses on a similar plan, the common pipe 
 would belong to their premises, would be "single" and " private," 
 and clearly maintained by those owners whose houses it served. 
 It is clear from these sections what were the objects, in respect of 
 drains, which the framers of the Act of 1875 had in view r , and 
 that, when they defined " drains," they contemplated the pipes 
 which sees. 23 and 25 required the owners to provide or see were 
 provided. There appears to be no justification to assume that 
 the definition as given in sec. 4 was intended to raise a drain to 
 the dignity of a sewer simply because it joined another drain. In 
 fact, the Amending Act of 1890 would seem to have been passed in 
 order to correct the view that where a common conduit carried to 
 a sewer the drainage of two or more houses belonging to different 
 owners, that common conduit was no longer a drain. Its real 
 object was to bring within the reach of sec. 41 of the P.H.A., 
 1875, that class of drainage conduit which, by force of the strained 
 definition of " drain," had begun to be placed outside its 
 operation, and to transfer to the shoulders of owners of houses, 
 which this class of conduit served, the burden of maintaining 
 them. In other words, that class of conduit or pipe which sees. 
 
 Q 
 
450 SANITARY LAW. 
 
 23 and 25 of the 1875 Act compelled owners to provide or see 
 were provided. Therefore, in regard to this vexed question of 
 what is a " drain/' we may say that, irrespective of the definition, 
 a pipe, in order to be a single private drain under sec. 19 of the 
 P.H. (Amend.) Act, 1890, must be such a pipe as owners could 
 be required to provide under sees. 23 and 25 of the P.H. A., 1875. 
 A necessary corollary to this is that a pipe to be a " drain " under 
 the P.H. A., 1875, must have as termini at one end one "building 
 or premises within the same curtilage," and at the other end " a 
 cesspool or other receptacle for drainage, or a sewer into which 
 the drainage of two or more buildings occupied by different 
 persons is conveyed." While the word "sewer" includes sewers 
 and drains of every description except drains to which the word 
 "drain" interpreted as aforesaid applies, and also except drains 
 "vested in or under the control of any authority having the 
 management of roads and not being a local authority under this 
 Act." 
 
 Canal. Under the C.B.A., 1877 and 1884, the term "canal" 
 includes any river, lake, water, or inland navigation " being within 
 the body of a country, whether it is or is not within the ebb or 
 flow of the tide." 
 
 Canal Boat. This includes any and every vessel, however 
 propelled, used for conveyance of goods along a canal, as 
 above defined, but does not include a ship registered under 
 the Merchant Shipping Act, 1894, unless the M.H. orders other- 
 wise, which it may do on the representation of a S.A, or any of 
 its inspectors. 
 
 Bye-laws and Regulations.— In respect of certain matters, 
 and under certain conditions expressly stated in the various Acts 
 dealing with the Public Health, sanitary authorities may make 
 bye-laws, having the force of law. These bye-laws are intended 
 rather to supplement than to summarize, vary, or supersede the 
 express provisions of the statute law. All 'bye-laws made by a 
 S.A. under and for the purpose of the Public Health Acts must 
 be under its common seal ; and any such bye-law may be altered 
 or repealed by a subsequent bye-law made pursuant to the pro- 
 visions of the Acts. But no bye-law is of effect, if repugnant to 
 the laws of England, or to the provisions of the Acts. A S.A. may, 
 by any bye-laws made by it, impose such reasonable penalties as 
 it thinks fit, not exceeding ^5 for each offence, and, in the case 
 of a continuing offence, a further penalty not exceeding 40^. per 
 each day after written notice of the offence ; but all such bye- 
 laws imposing any penalty must be so framed as to allow of the 
 recovery of any sum less than the full amount of the penalty. 
 Bye-laws do not take effect unless and until they have been 
 
BYE-LAWS AND REGULATIONS. 45 I 
 
 confirmed by the M.H., who have power to allow or disallow the 
 same as they think proper. The bye-laws, when confirmed, must 
 be printed and hung up in the office of the S.A., and a copy of 
 them must be delivered to any ratepayer of the district who applies 
 for them (see P.H.A. 1875, secs « I ^ 2 t0 l %5)- 
 
 Some bye-laws must be made by a local authority ; there are 
 others which may be made by both urban and rural authorities, 
 and others also which urban sanitary authorities alone are 
 empowered to make. In the greater number, the power to 
 make them is permissive. 
 
 Regulations differ somewhat from bye-laws, because with few 
 exceptions they do not require the approval of the M.H. They 
 may be simply passed as a resolution at a meeting of the authority, 
 and may be amended or rescinded at a subsequent meeting. In 
 certain cases, as, for instance, under sec. 125, P.H.A., 1875, relating 
 to the removal to hospital of infected persons brought by ships, a 
 regulation, just like a bye-law, has to be approved by a superior 
 authority, and its breach involves liability to a money penalty. 
 The same is the case in regard to regulations made by a S.A., 
 under the regulations as to Food Act, 1907, as to the importation, 
 storage, preparation, and distribution of food. 
 
 Urban Sanitary authorities are empowered to make bye-laws, 
 in respect of the following : — 
 
 Common Lodging Houses (P.H.A., 1875, sec. 80). 
 
 Cleansing and Scavenging and Nuisances (P.H.A., 1875, sec * 44)« 
 
 Tenement Houses and Lodging Houses (P.H.A., 1875, sec - 9°)« 
 
 Seamen's Lodging Houses (M.S. A., 1894, sec. 214). 
 
 New Streets and Buildings (P.H.A. , 1875, sec. 157, and Part III. P.H. 
 
 (Amend.) A., 1890). 
 Slaughter Houses (P.H.A., 1875, sec « 169). 
 Markets and Fairs (P.H.A., 1875, sec. 167). 
 Offensive Trades (P.H.A , 1875, sec. 113). 
 Hop and Fruit Pickers (P.H.A., 1875, sec. 314, and P.H. (Fruit-pickers) A., 
 
 1882). 
 Tents and Vans (H.W.C.A., 1885, sec. 9). 
 Mortuaries andCemeteries (P.H.A., 1876, sec. 141, and P.H. (Interments) A., 
 
 1879). 
 Open Spaces (P.H.A., 1875, sec. 164, and Open Spaces Act, 1887). 
 
 Buildings provided under H.W.C.A., 1903. 
 
 Means of Escape from Fire (F.W.A., 1901, sec. 15). 
 
 The Municipal Corporations Act, 1882, sec, 23, gives power 
 to municipalities or borough councils to make bye-laws for the 
 suppression and prevention of nuisances, not already punishable 
 in a summary manner by any other Act in force throughout the 
 borough. County councils have similar powers under the Local 
 Government Act, 1888, sec. 16. 
 
 Urban authorities can further make bye-laws under the 
 Housing of the Working Classes Act, 1890, for the regulation 
 
45 2 SANITARY LAW. 
 
 of all buildings provided under that Act or the Acts which it 
 supersedes. 
 
 Rural sanitary authorities have similar powers for making 
 bye-laws in respect of the following: (i) Private Scavenging; 
 (2) Common Lodging-houses; (3) Tenement Houses and Sea- 
 men's Lodging-houses ; (4) Hop and Fruit-pickers ; (5) Tents and 
 Vans ; (6) Mortuaries ; and (7) Under the Housing of the Work- 
 ing Classes Act, 1890. Further, by adopting portions of the P.H. 
 (Amend.) A., 1890, which are not expressly limited to urban 
 districts, rural sanitary authorities can make certain bye-laws as to 
 new and old buildings. The M.H. may confer on them any 
 other powers as to bye-laws which the Public Health Acts give to 
 urban authorities (P.H. A., 1875, sec ' 2 7^)« 
 
 Every sanitary authority must make bye-laws as to common 
 lodging-houses ; every urban sanitary authority must do the same 
 as to slaughter-houses ; the exercise of power as to other bye-laws 
 is optional. 
 
 The London County Council has power to make bye-laws for 
 the regulation of the plans, levels, width, surface, inclination and 
 materials of new streets and roads ; for the plan and sites of 
 buildings ; as to the dimensions, form, construction, cleansing and 
 repairing of pipes, drains and traps connected with sewers ; and 
 as to the construction, ventilation and cleansing of sewers (L.B.A., 
 1894, sec. 164, and certain unrepealed clauses of the Metropolitan 
 Local Management Acts). 
 
 Also under the P.H. (Lond.) A., 1891, for regulating the con- 
 duct of offensive trades, and the structure of the premises (sec. 
 19). For prescribing the times for removal of any faecal or 
 offensive matter in or through London, so as to avoid the creation 
 of a nuisance (sec. 16). As to the closing of cesspools and privies, 
 the removal and disposal of refuse, and as to the duties of the 
 occupier of any premises in connection with house refuse (idem). 
 As to water-closets, earth-closets, ash-pits, cesspools, receptacles 
 for dung, and the proper accessories thereof in connection with 
 buildings (sec. 39). Also as to tenement houses (sec. 94). The 
 power to make bye-laws under section 19 is permissive, but under 
 sees. 16, 39, and 94 is compulsory. Under the L.G.A., 1899, it 
 is the duty of each borough council to enforce the bye-laws and 
 regulations in force for the time being. 
 
 The Metropolitan sanitary authorities, under the same Act, 
 must make bye-laws for the control of nuisances arising from snow, 
 ice, salt, dust, rubbish, ashes, carrion, fish, or filth in the streets ; 
 or from offensive matters running from any manufactory, brewery, 
 slaughter-house, or dung-hill; for the prevention of keeping 
 animals on any premises in such place or manner as to be a 
 
BYE-LAWS AND REGULATIONS. 453 
 
 nuisance or dangerous to health ; and as to the paving of yards 
 and open spaces in connection with dwelling-houses (sec. 16). 
 For the keeping of water-closets supplied with sufficient water for 
 their effective action (sec. 39). For the cleansing and protecting 
 of all cisterns, tanks, etc., used for storing water for domestic 
 purposes, drinking, or the manufacture of beverages (sec. 50). 
 
 Similarly, in rural districts, the district council is the rural 
 sanitary authority. Where the number of councillors of any such 
 district is less than five, the M.H. may, by Order, nominate such 
 number of persons as are necessary to make up that number from 
 owners or occupiers of property situated in the district. The 
 persons so nominated are entitled to act and vote as members 
 of the rural S.A., but not further or otherwise. An alternative 
 procedure is for the M.H. to order the affairs of the district to be 
 administered by the district council of an adjoining district. Each 
 rural district council has all the powers, duties, and liabilities, as 
 a rural S.i\., as were exercised by the old boards of guardians. 
 They have also the same powers for appointing committees as 
 have the district councils of urban districts other than boroughs 
 (L.G.A., 1894, sec. 56). 
 
 The M.H. may, by a General Order, confer upon rural district 
 councils such urban powers as they think fit ; this is in addition 
 to their right, under the P.H.A., 1875, to grant urban powers for 
 particular areas, which right, under the 1894 Act, may be exer- 
 cised by the Board on the application of the county or parish 
 council concerned. 
 
 All district councils have the charge of highways. They also 
 administer the Acts relating to petroleum and infant life protec- 
 tion, and the licensing of knackers' yards — a duty hitherto carried 
 out by quarter sessions. In large rural districts, the district 
 council may appoint parochial committees for outlying parishes 
 to act as a resident subordinate authority, and as its agents. If 
 such exist, the members of these committees must be selected 
 from the members of the parish council. These parochial 
 committees are completely under the control of the rural S.A., 
 which made them, and have no jurisdiction beyond the places 
 for which they are formed. 
 
 By the L.G.A., 1894, parish councils and parish meetings are 
 constituted in rural districts. By sec. 8 of that Act, the parish 
 council has power to utilize any well, spring, or stream within 
 its parish, and power to drain, clean, cover, to remedy the con- 
 dition of ponds and stagnant pools ; also to acquire or hire land 
 for allotments, make official representation to the district council 
 under the Allotments Act ; or to the M.O.H. under the Housing 
 of the Working Classes Act, in regard to unhealthy areas and 
 
454 SANITARY LAW. 
 
 obstructive or unhealthy dwellings ; or to the M.H., for granting 
 of urban powers for their parish or any part of it. The district 
 council may delegate to the parish council any powers which it 
 may delegate to a parochial committee under the Public Health 
 Acts. A parish council may complain to the county council if 
 the rural district council have failed to provide or to maintain 
 sufficient drainage or water supply for the parish, or to enforce 
 any provision of the P.H.A. 1875. 
 
 Apart from expenditure under adoptive Acts, such as the Public 
 Health Amendment Act, 1890, the parish council must not incur 
 expenses involving more than a 6d. rate in any year, nor more than 
 a $d. rate without the consent of the parish meeting. They may 
 raise money on loan, but only with the approval of the parish 
 meeting, the county council, and the M.H. The parish meeting 
 has the exclusive power of adopting certain optional Acts, in- 
 cluding the above-named, the Burial Acts, the Baths and Wash- 
 houses Acts, the Lighting and Watching Act, 1833, and the 
 Public Improvements Act, i860. 
 
 In order to simplify sanitary administration, boundaries of 
 local sanitary areas are adjusted so as to prevent intersection of 
 those which define counties, county districts, unions, and parishes. 
 Small rural parishes are grouped into workable units for parish 
 council purposes, but each has its own parish meeting. Although 
 by the Act of 1894 some few sanitary powers are given to 
 parish councils, those powers in no way derogate from the 
 sanitary obligations of a district council, which is the true rural 
 sanitary authority. 
 
 Although the powers conferred on urban and rural sanitary 
 authorities are in many respects identical, they are not entirely 
 so. By sec. 276, P.H.A., 1875, the M.H. may, on application 
 of a rural S.A., or of persons rated to the relief of the poor, whose 
 assessments amount to one-tenth of the nett rateable value of the 
 district, declare, by Order, any provision of that Act in force in 
 an urban district to be in force in such rural district or part 
 thereof. In like manner the Private Street Works Act, 1892, 
 and the P.H. (Amend.) Act, 1890, may be put in force in the 
 whole or part of any rural sanitary district. In amplification of 
 the foregoing, by sec. 25 (7) of the L.G.A., 1894, similar powers 
 may be exercised by the M.H., on application of a county council, 
 or with respect to any parish or part thereof, on application 
 of the parish council. Experience has shown that the pro- 
 visions of the P.H. A., 1875, hitherto most frequently put in force, 
 are sees. 42, 44, 157, and 158, relating to cleansing and watering 
 of streets, and making of bye-laws as to nuisances and new 
 buildings. Other sections which are occasionally put in force 
 
BYE-LAWS AND REGULATIONS. 455 
 
 are 112 and 114, relating to offensive trades, and sees. 169, 170, 
 which regulate slaughter-houses. 
 
 The same authorities may make bye-laws for the removal to 
 hospital, or detention therein, of persons suffering from infectious 
 disease (sec. 66). For preventing the fouling of tents, vans, sheds, 
 and similar structures used for human habitation, and the spread 
 of infectious disease by the inhabitants thereof (sec. 9). In 
 relation to tenement houses, under sec. 8 of H.W.C.A., 1885, 
 these same authorities must also enforce any bye-laws made by 
 the London County Council under sees. 16, 39, and 94 of the 
 P.H. (Lond.) A., 1891. 
 
 In the City of London, similar powers are vested in the Cor- 
 poration under the City of London Sewers Acts, 1848 and 185 1, 
 the Public Health (Lond.) Act, 1891, the Gardens in Towns 
 Protection Act, 1863, the Metropolitan Open Spaces Act, 1877 
 and 1 88 1, and the Open Spaces Act, 1887. 
 
 Under the Dairies Order, 1885 and 1899, any S*A. may make 
 regulations for any of the following purposes : (a) for the inspec- 
 tion of cattle in dairies ; (b) for prescribing and regulating the 
 lighting, ventilation, drainage, cleansing, and water supply of 
 dairies, and cowsheds ; (c) for prescribing precautions to be taken 
 by purveyors of milk against infection ; (d) for securing the clean- 
 liness of milk-stores, milkshops, and milk vessels, used for con- 
 taining milk for sale. 
 
 A S.A., subject to approval by the M.H., may make Regula- 
 tions for the removal to hospital, and detention there as long as 
 necessiry, of all persons who may be brought within their district 
 by either boat or ship, and who may be infected with an infectious 
 disease (P.H. A., 1875, sec « I2 5)« They have also power to make 
 Regulations for the management of places provided by them for 
 making post-mortem examinations ordered by a coroner (sec. 
 
 143)- 
 
 The M.H. has power to make Regulations under sees. 130 and 
 
 134, P.H. A., 1875, in relation to cholera, and other dangerous 
 infectious diseases. These powers are extended under P.H. A., 
 1896. 
 
 From time to time, the M.H. has prepared and issued " model 
 bye-laws " to serve as guides to sanitary authorities when seeking 
 to frame bye-laws. As these models have been very generally 
 adopted, subject to occasional modifications, by various local 
 authorities, a summary of them will be given under their proper 
 heading, where their provisions may help to a better appreciation 
 of the requirements of the several Public Health Acts. The 
 following have been issued up to the present time ; — 
 
4 c6 SANITARY LAW. 
 
 Private Scavenging. Houses let in Lodgings. 
 
 Prevention of Nuisances. Cemeteries. 
 
 Common Lodging Houses. Mortuaries. 
 
 New Streets and Buildings. Hop-pickers. 
 
 Markets. Offensive Trades, including those of a 
 Slaughter-houses. Blood-boiler. Leather-dresser. 
 
 Hackney Carriages. Bone-boiler. Tanner. 
 
 Horses, etc., let for hire. Fell-monger. Fat-melter. 
 
 Pleasure-boats. Soap-boiler. Glue-maker. 
 
 Pleasure-grounds. Tallow-melter. Size-maker. 
 
 Public Bathing. Tripe-boiler. Gut-scraper. 
 
 Baths and Wash-houses. Blood-drier. 
 
 Supplementary to these model bye-laws, various regulations in 
 regard to the management of mortuaries and cemeteries have 
 been issued by the Home Secretary. 
 
 Cleansing and Scavenging.— By sec. 42, P.H.A., 1875, every 
 S.A. may, and when required by the M.H. shall undertake or 
 contract for the removal of house refuse and cleansing of privies, 
 ashpits, etc. Further, every urban S.A. and every rural S.A. 
 invested by the M.H. with the requisite powers may, and when re- 
 quired by the Ministry shall themselves undertake or contract for 
 the proper cleansing and watering of streets for the whole or any 
 part of their district. All refuse, so collected, shall be the property 
 of the local authority, to be sold or otherwise disposed of. More- 
 over, if Part III. P.H. (Amend.) A., 1890, has been adopted, the 
 S.A. may, under sec. 26 (2) of that Act make bye-laws imposing 
 on occupiers duties to facilitate the removal of refuse. Any 
 person obstructing removal to be liable to a penalty not exceeding 
 ^5, except as regards refuse, etc., which the occupier intends to 
 employ for his own use, unless he meanwhile suffers it to become 
 a nuisance. If the S.A., having themselves undertaken or con- 
 tracted for the removal of house refuse from premises, or the 
 cleansing of earth-closets, privies, ashpits, and cesspools, neglect, 
 without reasonable excuse, to remove any refuse within seven 
 days of receiving a remonstrance from the occupier, they shall be 
 liable to pay to him 5^. for each further day's neglect (sec. 43, 
 P.H.A., 1875). An urban S.A. may, by sec. 45 of the same Act, 
 provide receptacles and places for the temporary deposit of the 
 matter collected. 
 
 By sec. 44, P.H. A., 1875, the S.A. has power to make bye- 
 laws imposing the duty of cleansing footways, pavements, ashpits, 
 privies, cesspools, and removing house refuse when they them- 
 selves do not contract or undertake to do the same, and may 
 make bye-laws for the prevention of nuisances from accumulations 
 of snow, filth, ashes, etc., and from the keeping of animals. 
 
 Model bye-laws have been issued for the prevention of these 
 nuisances, (a) They require the house refuse to be removed 
 
CLEANSING AND SCAVENGING. 457 
 
 once at least every week, and prescribe the same interval for 
 the cleansing of every ashpit and privy, and every earth-closet 
 furnished with a movable receptacle for faecal matter, and with 
 suitable means or apparatus for the frequent and effectual 
 application of dry earth to such matter. Where the receptacle 
 is fixed, the time allowed is three months, and a like period is 
 prescribed for the cleansing of cesspools, (b) So far as nuisances 
 from snow are concerned, the occupier of any premises must clear 
 away snow from the footways and pavements adjoining his 
 premises, as soon as possible after it ceases to fall. (c) The 
 refuse from any premises shall only be removed in a suitable 
 covered receptacle or carriage, and if removed from premises 
 within 20 yards of any dwelling, place of business, or public 
 building, only between 7 a.m. and 9 a.m. from November to 
 February, and between 6 a.m. and 8 a.m. from March to October. 
 Refuse must not be deposited upon any road, and any refuse 
 accidentally falling upon a road must be immediately gathered up 
 and the place cleansed, (d) No load of filth must be deposited 
 for more than 24 hours within 100 yards of any street, dwelling, 
 public building, or place of business. Night soil deposited for 
 agricultural purposes upon land within 100 yards of a street, 
 dwelling, etc., and not deodorized, must at once be dug or 
 ploughed into the ground, (e) Swine must not be kept within 
 100 feet of any dwelling, nor cattle where they can pollute water 
 likely to be used for drinking, domestic, or dairy purposes, or for 
 manufacturing drinks. The same prohibitions apply to the storage 
 of dung. Premises wherein are kept any swine, cattle, horses, etc., 
 must be provided with proper receptacles for manure, and with 
 efficient drainage ; the receptacle must be water-tight, covered, 
 and entirely above the level of the ground, and it must be cleansed 
 at least once a week ; the drain must be properly constructed and 
 kept in order at all times, so as to convey all liquid filth to a sewer, 
 cesspool, or other suitable receptacle. 
 
 If the M.O.H. or two medical practitioners certify that any 
 house or part thereof is so filthy as to endanger health, or that 
 the whitewashing and purifying thereof would tend to prevent 
 infectious disease, the S.A. may require the owner or occupier 
 to cleanse, etc., and in his default may themselves do what is 
 necessary (P.H.A., 1875, sec. 46). 
 
 Sec. 47 of the same Act prohibits not only keeping of swine 
 in dwelling-houses so as to be a nuisance within an urban district, 
 but also suffering stagnant water to lie in cellars or dwellings 24 
 hours after written notice from the S.A, and allowing contents of 
 privies and cesspools to overflow or soak out, on a penalty not 
 exceeding 405-., and a daily penalty not exceeding 5-r. after notice, 
 
458 SANITARY LAW 
 
 
 and authorizes the abatement of the nuisance by the S.A. at the 
 occupier's expense. Moreover, a sanitary inspector in an urban 
 district may give notice to the owner of any offensive accumulation 
 of matter, or to the occupier of the premises whereon it exists,, to 
 have it removed within twenty-four hours, failing which the S.A. 
 may remove the same (sec. 49). An urban authority may give 
 public notice requiring the periodical removal of manure from 
 mews, and other public premises, and enforce the same under 
 penalty (sec. 50). 
 
 In cases where Part III. P.H. (Amend.) A., 1890, is in force, 
 by sec. 27 of the same, the S.A. has powers for keeping common 
 courts and passages clean, apportioning the expenses incurred to 
 the occupiers of adjacent premises. 
 
 In the Metropolis, the provisions for cleansing and scavenging 
 under the P.H. (Lond.) A., 1891, are somewhat more stringent 
 than those of the P.H. A., 1875, which controls the main actions 
 of sanitary authorities in the provinces. By sees. 29 and 30 of 
 the London Act, the S.A. must cleanse streets, footpaths, cess- 
 pits, earth-closets, and privies. They must remove house refuse 
 at proper intervals, and trade refuse also, if required to do so, on 
 payment. As to what is or is not trade refuse shall, on complaint 
 of either party, be determined by a petty sessional court, such 
 decision being final (sec. 33 (2)). The S.A., further, may 
 undertake the collection of manure and other refuse, on request ; 
 or may by order, require periodical removals by owner (sec. 36). 
 
 Sec. 16 (2) of the London Act empowers the county council 
 to make bye-laws (a) for prescribing the times for removal of faecal 
 or other offensive matter through London, and for providing that 
 the vessel or carriage therefor is properly constructed so as to 
 prevent any nuisance; and (b) as to the closing and filling of 
 privies, removal of refuse generally, and as to the duties of the 
 occupiers in relation to facilitating the removal of it by the 
 scavengers of the S.A. Further, a constable may arrest without 
 warrant and take before a justice any person found committing 
 an offence against such bye-laws, and who refuses to give his true 
 name and address. Swine may not be kept in London within 
 forty yards of a street or public place, nor be allowed to stray 
 into any public place. A court may prohibit the keeping of any 
 animal in any specified place shown to be unfit for the purpose 
 (sec. 17). 
 
 Sewers and Disposal of Sewage.— By the P.H.A., 1875 
 (sec. 13), it is enacted that all sewers, except certain private 
 sewers are vested in the S.A. of the district. The exceptions 
 mentioned in the section are (1) Sewers made by a person or 
 persons for his or their profit; (2) sewers made and used for 
 
 
SEWERS AND DISPOSAL OF SEWAGE. \$g 
 
 draining or improving land under any local or private Act, or tor 
 irrigation ; (3) sewers under any commissioners of sewers ap- 
 pointed by the Crown. The S.A. may purchase (sec. 14), or 
 construct (sec. 15) sewers. They must provide such sewers as 
 are necessary for effectually draining their district, having, by 
 sec. 16, powers ot taking them through, across, or under lands 
 and streets. Sec. 308 of the Act provides for compensation 
 for damage, to be ascertained by arbitration. The sewers must 
 be so constructed, covered, ventilated, and kept as not to be a 
 nuisance or injurious to health, and must be properly cleansed 
 (sec. 19). The performance of these duties by a S.A. can be 
 enforced on complaint by individuals (sec. 299), while further 
 powers, in this respect, are given by sees. 16 and 19 of the 
 L.G.A., 1894, to county councils, on complaint by a parish council 
 of a defaulting rural sanitary authority. 
 
 Under sec. 7, Rivers Pollution Prevention Act, 1876, every 
 S.A. must give facilities for factories to drain into sewers, but 
 provision is given for the protection of sewers from injurious 
 matters such as anything which may impede the flow of their 
 contents, any chemical refuse, waste steam, or water or liquid 
 heated above no° F., by sees. 16 and 17, P.H. (Amend.) A., 
 1890. The restrictions imposed by sees. 32, ^^, and 34 of 
 the P.H. A., 1875, on the execution of sewerage works by a S.A. 
 outside its own district, involve the giving of a public notice, and 
 in case of objection, the work not to be commenced without 
 sanction of the M.H., who may appoint an inspector to make 
 inquiry and report. 
 
 For the protection of the sewers of an urban sanitary authority, 
 sec. 26, P.H. A., 1875, provides a penalty for unauthorized 
 buildings over them; and sees. 150 and 151 give power to the 
 S.A. to compel the sewering of private streets, subject to any bye- 
 laws the authority can get confirmed by the M.H. Powers are 
 given by sec. 27 of the same Act for the treatment and disposal 
 of sewage, but sec. 17 expressly insists that such disposal of 
 sewage must not be into streams, unless purified before discharge ; 
 this latter section, however, needs to be read in connection with 
 the Rivers Pollution Prevention Acts, 1876 and 1893, which give 
 a certain amount of protection to sanitary authorities in respect of 
 the pollution of streams and rivers by sewage channels used, con- 
 structed, or in process of construction at date of passing of the 
 Act of 1876. Sees. 28, 29, and 30 of the P.H.A., 1875, further 
 give power to the S.A. to deal with land appropriated to sewage 
 purposes, to contribute to works executed by others for the dis- 
 posal of the sewage, and to agree for communication of sewers 
 with sewers of adjoining districts. 
 
/\6o SANITARY LAW. 
 
 The incidence of the charge of sewage and other public 
 sanitary works in urban districts is usually made by a general 
 district or borough rate. In rural districts, the incidence of 
 charge of expense of sewerage and other sanitary works are not 
 made on the entire district, but constitute a separate charge on 
 parishes or parts of parishes for which the works have been carried 
 out, and the areas liable to contribute are termed " contributory 
 places" (sec. 229). There are four kinds of contributory places: 
 (1) a rural sanitary authority may, subject to approval by the 
 M.H., constitute any portion of its area a " special drainage 
 district" for the purpose of charging thereon exclusively the 
 expenses of sanitary works, the cost of which is not spread over 
 the entire district, and thereupon such area becomes a " con- 
 tributory place ; " (2) where no part of a parish is situate in a 
 special drainage district, or in an urban sanitary district, the entire 
 parish is a contributory place ; (3) where no part of a parish is in 
 an urban sanitary district, but part of it is in a special drainage 
 district, the part not in a special drainage district is a contributory 
 place ; (4) where part of a parish is in an urban sanitary district, and 
 part in a rural sanitary district, so much of it as is not in an urban 
 district or special drainage district is a contributory place (sec. 229). 
 
 In the Metropolis, outside the city, the county council are the 
 local authority for the purposes of the mam sewerage and disposal 
 of the sewage of London, while the borough councils are the local 
 authorities for the purpose of the sewerage and drainage, other 
 than the main sewerage. The powers of the county council, as 
 regards main sewerage are derived from the Metropolis Manage- 
 ment Act, 1885, taken in conjunction with a similar Act of 1862, 
 and the Metropolitan Main Drainage Act, 1858. 
 
 While the main sewers are to be constructed and kept so as 
 not to be a nuisance, the county council has power to declare 
 sewers to be main sewers, and to take jurisdiction over sewerage 
 and drainage matters belonging to the boroughs, also to control 
 the borough councils in the construction of sewers, etc., by means 
 of bye-laws. The general powers of the London County Council 
 in respect of sewerage and disposal of sewage are very similar to 
 those of the sanitary authorities in the provinces under the P.H.A., 
 1875. As relates to procedures for the prevention of floods, the 
 powers of the county council, by inheritance from the Metro- 
 politan Board of W T orks, are derived from the Metropolitan 
 Management (Thames River Prevention of Floods) Amendment 
 Act, 1879. All sewers, etc., within the City are vested in the 
 Corporation, who have full power over them and all drains com- 
 municating with the public sewers, under the City of London 
 Sewers Act, 1848. 
 
HOUSE DRAINAGE. 461 
 
 By the Metropolis Management Act, 1855, sec. 68, all sewers, 
 other than those now vested in the county council and the City 
 Corporation, are vested in the borough councils, who from time 
 to time must repair, maintain, alter, or extend as may be 
 necessary ; but no new sewers can be made in the administrative 
 county of London without the approval of the county council. 
 The powers given by the above provisions are extended in certain 
 cases to areas outside the Metropolis by sec. 58 of the Metropolis 
 Management Act, 1862. The Act of 1855 (sees. 73 to 75) further 
 provides for the ventilation, trapping, cleansing, inspection, and 
 proper connection of drains with sewers on the part of the sanitary 
 authorities; while sec. 202 of the same Act gives the local 
 authorities power to make bye-laws as to drains. For the pur- 
 poses of their sewers, and for other purposes of the Metropolis 
 Management Acts, every vestry or district board has the same 
 power as the county council to purchase lands. These powers of 
 purchase, however, are not compulsory (sees. 151, 152). 
 
 House Drainage, Water-Closets, Privies, etc. — Every sanitary 
 authority, by sees. 22 to 25 P.H.A., 1875, nas power to enforce 
 drainage of undrained houses, and in certain cases to close existing 
 drains on condition of providing others. These drains must lead 
 to the public sewer if there be any within 100 feet of the site of 
 the house; if not, to a covered cesspool in such position (not 
 under a house) as the S.A. may direct. Failing compliance, the 
 authority may carry out the work and recover in a summary 
 manner the expenses incurred from the owner, or may by order 
 declare the same to be " private improvement expenses." These 
 private improvement expenses may be made payable by instalments 
 with interest. They may, moreover, be levied on the occupier, 
 whereas the expenses, if incurred summarily, will only be recover- 
 able from the owner. It occasionally happens that owing to the 
 delay in construction of sewers, houses have been supplied with 
 cesspools and effectual drains leading thereto. In those cases 
 the S.A. are under no obligation to pay the costs of drains 
 necessary for enabling the house to discharge its sewage into the 
 new sewers. Where the sewer is in the same sanitary district as 
 that in which the premises are situate, the owner or occupier, 
 upon giving due notice and complying with the regulations of the 
 authority as to the mode in which the communication is to be 
 made, is entitled to carry drains into the public sewer. In places 
 where Part III. P.H. (Amend.) A., 1890, has been adopted, by 
 sec. 18 of that Act, the owner or occupier has a right to require 
 the S.A. to make the communication at his cost. Where the 
 sewer is in another sanitary district, the communication must be 
 made on such terms and conditions as may be agreed upon between 
 
462 SANITARY LAW. 
 
 the owner or occupier and the S.A. to whom the sewer 
 belongs. 
 
 Where any drain or cesspool is a nuisance, or injurious to 
 health, the S.A. may take proceedings to remedy the matter either 
 under sec. 41, P.H.A., 1875, or under the provisions of the same 
 Act relating to nuisances. All the foregoing provisions apply to 
 existing houses and drains without regard to the date of their 
 construction, in both urban and rural districts. 
 
 In urban districts, and in rural districts, or contributory places 
 endowed with urban powers by sec. 276, P.H.A., 1875, not 
 only may no house be built, or rebuilt after having been pulled 
 down to or below the ground floor, or be occupied after having 
 been built or so rebuilt until proper covered drains have been 
 constructed and duly connected with either a sewer or cesspool, 
 as above indicated, to the satisfaction of the S.A. (P.H.A., 1875, 
 sec. 25), but the authority may make bye-laws as to the mode in 
 which connections between drains and sewers are to be made 
 (sec. 157). This 157th section of the 1875 Act ^ s on ty of limited 
 extent, as it provides that no bye-law made under it shall affect 
 any building erected in any place which, on August n, 1875, 
 was included in an urban sanitary district before the Local 
 Government Acts came into force in such place, or any building 
 erected in any place which, on that date, was not included in any 
 urban sanitary district, before such place became constituted or 
 included in an urban district, by virtue of any order of the M.H. 
 subject to this enactment. Nor might any bye-law made under 
 the section apply to buildings belonging to railway companies, 
 and used for the purposes of such railways under any Act of 
 Parliament. In places where Part III. P.H. (Amend.) A., 1890, 
 has been adopted, sec. 23 of this same Act has extended the 
 operation of this 157th section of the 1875 Act to buildings 
 erected before the time mentioned and to rural sanitary districts. 
 Rural S.A.s can therefore now, by adopting this part of the 1890 
 Act, obtain these very important powers throughout their districts 
 without the intervention of any order of the M.H. 
 
 The law relating to privies, water-closets, excrement and refuse 
 disposal resembles thai relating to house drainage inasmuch as it 
 is contained partly in statutory enactments applicable to both 
 urban and rural sanitary districts, and partly in bye-laws applicable 
 only to urban districts and to those rural sanitary districts or 
 contributory places to which it has been specially applied by 
 order of the M.H. The general statutory enactments in regard 
 to these matters of excrement and refuse disposal are contained 
 in the P.H. A., 1875, sees. 35 to 45, and practically amount to the 
 following : — 
 
HOUSE DRAINAGE. 463 
 
 It is unlawful to erect any house without a sufficient water- 
 closet, earth-closet or privy, and an ashpit with proper doors and 
 coverings ; and the same must be provided for any existing house 
 on the order of the S.A., who may require a separate closet for 
 each house (sees. 35, 36, 37). The S.A. may order sanitary con- 
 veniences in factories where persons of both sexes are employed 
 (sec. 38), while the Coal Mines Regulation Act, 1887, sec. 74, 
 makes the same provision applicable to parts of mines above 
 ground in which women and girls are employed. Every S.A. must 
 see that all drains, closets, ashpits, and cesspools are properly 
 constructed and kept (P.H.A., 1875, sec. 40); while urban 
 sanitary authorities may provide public urinals, closets, or re- 
 ceptacles for refuse (idem. 39-45). On the written application 
 of any person that any drain, closet, ashpit, or cesspool is a 
 nuisance, the S.A. may, by writing, empower their surveyor or 
 inspector, after giving 24 hours' notice, to enter the premises and 
 open the ground; if any defect is found, the S.A. must serve 
 notice upon the owner or occupier to do the necessary work, but 
 if there is no defect the authority must close the ground and make 
 good any damage (P.H.A., 1875, sec « 4 1 )* 
 
 Under Part III. P.H. Acts Amendment Act, 1907, local 
 authorities have fuller powers in regard to these matters, notably 
 right of entry for purposes of inspection on the report of one of its 
 officers ; further they have power to order such number of closets 
 in a domestic building as they shall deem necessary to the size of 
 the building. They also have power to deal with any urinal or 
 sanitary convenience opening on to a public street, and to insist 
 on the provision of urinals in public houses or places of refresh- 
 ment or amusement. On the report of one of its responsible 
 officers a S.A. is authorized to apply the smoke or coloured water 
 test (not water under pressure) to drains, but the consent of the 
 owner or occupier must be given or an order of a Court of 
 Summary Jurisdiction must be obtained. 
 
 There have been issued a series of model bye-laws relating 
 to the various matters for which bye-laws may be made by a 
 S.A. under the foregoing provisions. Their general provisions 
 are sufficiently indicated in the following summary : — 
 
 Drainage. — Damp sites must be drained by earthenware field 
 pipes properly laid to a suitable outfall, but not directly communi- 
 cating with any sewer, or cesspool, or drain containing sewage. 
 Rain pipes must be provided to carry away all water falling on 
 the roof without causing dampness of the walls or foundations. 
 The level of the lowest story must be such as to allow of the 
 construction of a drain sufficient for the drainage of the building 
 communicating with a sewer at a point above the centre of the 
 
464 SANITARY LAW. 
 
 sewer. All drains for sewage must be made of impervious pipes 
 4 inches or more in internal diameter, laid with a proper fall in a 
 bed of concrete, and with water-tight joints. Every drain inlet 
 not intended for ventilation must be trapped. No drain conveying 
 sewage must pass under a building unless no other rnode of 
 construction is practicable; in that case it must be laid in a 
 direct line for the whole distance beneath the house, and must be 
 embedded in and covered with concrete 6 inches thick all round, 
 and must be laid at a depth below the surface at least equal to its 
 diameter, and lastly, must be ventilated at each end of the portion 
 beneath the building. The main drain must be trapped at a point 
 within the curtilage, but as distant as practicable from the building. 
 Branch drains must join other drains obliquely in the direction of 
 the flow. 
 
 There must be at least two untrapped ventilating openings 
 into the drains, according to one of the following alternative 
 arrangements : — (1) One opening consists of a shaft or discon- 
 necting chamber opening at or near the ground level, and situated 
 as close as possible to the trap specified above, but on the house 
 side of it ; the other opening is a pipe or shaft carried from a 
 point as far distant as possible from the said trap, that is, as near 
 as possible to the head of the drain, vertically upwards in such 
 manner and to such height (in no case less than 10 feet) as to 
 prevent any escape of foul air into any building ; but (2) if more 
 convenient, the relative positions of these openings may be 
 reversed, the shaft being placed near the trap, and the opening 
 near the ground level at the head of the drain. The ground-level 
 opening must have a grating, with apertures equal in total area to 
 the sectional area of the drain. The pipe or shaft at the other 
 end of the drain (whether used as a soil-pipe or not) is required 
 to have a sectional area equal to that of the drain, and in no case 
 to be less than 4 inches ; all bends and angles are to be avoided 
 as far as practicable. 
 
 No drain inlet is permitted within a building except the inlet 
 necessary for a water-closet. Every soil-pipe must be at least 
 4 inches in diameter, must be placed outside the building, and 
 must be continued upwards in full diameter without bends or 
 angles, to such a height and such a point as to afford a safe outlet 
 for sewer air. This height and point will usually be above the 
 highest part of the roof of the building to which the soil-pipe is 
 attached, and, where practicable, not less than 3 feet above 
 any window within 20 feet measured in a straight line from the 
 open end of such soil-pipe. There must be no trap between the 
 soil-pipe and the drain to which it leads, nor in any part of 
 the soil-pipe, except such as may be necessary in the construction 
 
HOUSE DRAINAGE. 465 
 
 of the water-closet. The waste-pipe from a slop sink must con- 
 form to the same requirements as a soil-pipe. The waste-pipe 
 from any other sink, bath, or lavatory, the overflow-pipe from 
 any cistern and from any " safe " under a bath or water-closet, 
 and every pipe for conveying waste water, must be taken through 
 an external wall and must discharge in the open air over a 
 channel leading to a trapped gully grating at least 18 inches 
 distant. 
 
 Waier-closets must have a window opening directly into the 
 external air, and measuring 2 feet by 1 foot clear of the frame ; 
 and, in addition to the window, adequate means of constant 
 ventilation by air-bricks, air-shafts, etc. Such closets, if within 
 the building, must adjoin an external wall. The water must be 
 supplied to a water-closet by means of a special cistern. The 
 apparatus must be suitable for effectual flushing and cleansing of 
 the basin ; the basin must be made of non-absorbent material, and 
 of such shape and capacity as to receive and contain a sufficient 
 quantity of water, and to allow all filth to fall free of the sides 
 directly into the water. " Containers " and " D traps " are 
 forbidden. 
 
 Earth-closets are subject to the same conditions as water-closets 
 so far as regards position, lighting, and ventilation. Proper 
 arrangements must be made for the supply of dry earth, and its 
 effectual and frequent application to the excreta ; also for con- 
 venience of scavenging, and for exclusion of rainfall and drainage. 
 The receptacle for excreta, whether fixed or movable, must be so 
 constructed as to prevent absorption or escape of the contents, 
 and to exclude rainfall and drainage ; if fixed, its capacity must 
 not be greater than may suffice for three months, nor in any case 
 greater than 40 cubic feet, and it must in every part be 3 inches 
 above the ground. In the case of earth-closets placed inside 
 houses, the maximum limit of size may with advantage be reduced 
 to 2 cubic feet. 
 
 Privies must not be erected within 6 feet of a dwelling, public 
 building, or place of business, nor within 50 feet of any water 
 likely to be used for drinking or domestic purposes, or for manu- 
 facturing drinks, nor otherwise in such a position as to entail 
 danger of the pollution of such water. Privies must be built so 
 as to admit of convenient scavenging, without carrying the contents 
 through any dwelling, public building, or place of business. There 
 must be an opening for ventilation at the top ; the floor must be 
 paved, and raised 6 inches above ground in all parts, with a. fall 
 of half an inch per foot towards the door. The receptacle may 
 be fixed or movable. If movable, as in pail-closets, the floor 
 of the area beneath the seat must be flagged or asphalted, and 
 
466 SANITARY LAW. 
 
 raised 3 inches above the ground level, and all the sides of the 
 said area must be made of flag, slate, or brick, at least 9 inches 
 thick, and rendered in cement. If the receptacle is fixed, it must 
 be in every part 3 inches above the ground level, and its capacity 
 not exceeding 8 cubic feet, presuming that the scavenging will be 
 done weekly : suitable means or apparatus must be provided in 
 connection with the privy for the application of ashes, dust, or 
 dry refuse to the filth deposited ; and the receptacle must be so 
 constructed that the contents may not at any time be exposed 
 to rainfall or to the drainage of any waste water or liquid 
 refuse from any adjoining premises, while at the same time 
 conveniently accessible for scavenging; the materials and con- 
 struction must be such as to prevent any absorption by any part 
 of it of any filth deposited therein, or any escape by leakage 
 or otherwise of its contents. It must in no way be connected 
 with a drain. 
 
 Cesspools must not be constructed within 50 feet of any 
 dwelling, public building, or place of business, nor within 100 feel, 
 of any water likely to be used for drinking or domestic purposes, 
 or for manufacturing drinks, or otherwise in such a position as to 
 entail danger of pollution of such water. Cesspools must be so 
 constructed and placed as to conveniently admit of scavenging 
 and cleansing without carrying the contents through any dwelling, 
 public building, or place of business. They must not be con- 
 nected with any sewer. They must be covered over by an arch 
 or otherwise, and adequately ventilated ; they must be constructed 
 of brick in cement, rendered inside with cement, and with a 
 backing of at least 9 inches of clay. 
 
 Ash-pits must not be constructed within 6 feet of any dwelling, 
 public building, or place of business, nor within 50 feet of any 
 water likely to be used for drinking or domestic purposes, nor 
 otherwise in such a position as to entail danger of the pollution 
 of such water. Ash-pits must be so placed and constructed as to 
 conveniently allow of scavenging without carrying the contents 
 through any dwelling, public building, or place of business. The 
 capacity must not exceed 6 cubic feet, or such less capacity as 
 may suffice for a period not exceeding one week. The walls must 
 be of flag, slate, or brick, at least 9 inches thick, and rendered 
 inside with cement ; the floor must be flagged or asphalted, and 
 raised at least 3 inches above the ground level. The ash-pit must 
 be roofed and ventilated, and provided with a door so arranged 
 as to allow of the convenient removal of the contents, and to 
 allow also of being closed and fastened. The ash-pit must not be 
 connected with any drain. 
 
 In the Metropolis, in regard to all the foregoing matters, the 
 
WATER SUPPLY. 467 
 
 London County Council, by sec. 39 (1) of the P.H. (Lond.) 
 A., 1 89 1, are empowered to make bye-laws, which it is the duty 
 of every S.A. in London outside the City to enforce and observe. 
 Bye-laws made by the county council under this Act do not, how- 
 ever, extend to the City ; but in that area analogous bye-laws can 
 be made by the Corporation, who, as before stated, are the local 
 authority. These bye-laws, whether made by the county council 
 or by the City Corporation under the London Act of 1891, are 
 subject to the provisions of sees. 182 to 185 of the P.H. A., 1875, 
 as already explained in connection with bye-laws made by any 
 S.A. in the provinces (see p. 440). In their main provisions the 
 bye-laws in force in the administrative county of London and 
 in the City accord closely with those suggested as models. 
 
 The obligations and powers of a S.A. in London in relation 
 to house drainage and the removal of refuse are very similar to 
 those of a sanitary authority in other parts of the country. A new 
 house must have " one or more water-closets, as circumstances 
 may require," with proper water supply, trapped soil-pan, and 
 other accessories. The same applies to all houses, irrespective of 
 date, under notice from the S.A. (P.H. (Lond.) A., sec. 37). 
 A privy or earth-closet may only be substituted if the available 
 sewerage and water supply is insufficient for a water-closet. Any 
 person who may think himself aggrieved by any notice or act of 
 the S.A. may appeal to the county council, whose decision is 
 final. These appeals are governed by sec. 126 of the London 
 Act. Penalties are prescribed for (a) constructing or reconstruct- 
 ing water-closets, etc., not in accordance' with this Act, or any 
 bye-laws, or in defiance of notice or prohibition ; (b) for dis- 
 continuing any such water supply without lawful authority ; (c) 
 illegally or wilfully injuring or constructing a drain or water-closet 
 so as to create a nuisance or danger to health (sec. 41). 
 
 Water Supply. — Owing to the privileges granted, from time to 
 time, to companies and other corporate bodies, sanitary authorities 
 are under certain restrictions as to their supplying water. Where 
 a water company has parliamentary powers to supply water over 
 any given area, the S.A. must give notice to the company stating 
 the purposes for which and extent to which it requires water ; and 
 if the company are able and willing to supply sufficient and proper 
 water for the purposes of the local authority, this latter body may 
 not construct any water- works within that area (P.H. A., 1875, 
 sec. 52). Moreover, sec. 332 of the Act provides that when 
 the supply of water must be taken from a running stream, the 
 S.A. before abstracting water from such stream, river, or source, 
 must obtain the consent in writing of any person or persons who 
 have prior claims upon those streams or sources. 
 
468 SANITARY LAW. 
 
 When not hampered by either of the foregoing restrictions, 
 any S.A. may construct works for supplying any part of their 
 district with water, or may take on lease, hire, or purchase works 
 (with the sanction of the M.H.), or contract for the . supply 
 (P.H.A., 1875, sec. 51). When a S.A. supply water within their 
 district, they have the same powers and are under the same 
 restrictions for carrying their mains within and without their 
 district as they have and are subject to in respect of their sewers 
 (sec. 54). The water supplied must be pure and wholesome, and 
 under sufficient pressure as will carry the same to the top storey 
 of the highest dwelling-house in the district supplied. There is, 
 however, no obligation to provide a constant supply under pressure 
 (sec. 55). The S.A. have power to charge water-rates and rents 
 in respect of premises to which they supply water, while all public 
 cisterns, pumps, wells, etc., used for the gratuitous supply of water 
 to the inhabitants of a district, vest in and are under the control 
 of such authority (sees. 56 and 64). 
 
 The same Act (sec. 62) gives any S.A. power to require houses 
 which are without a proper water supply to be so supplied, if it 
 can be furnished at a cost not exceeding the water-rate authorized 
 by any local Act or twopence per week, or such other cost as the 
 M.H. may, upon application, determine to be reasonable. In 
 order to guard against the pollution of sources of water supply, 
 the S.A. have power to proceed against offenders (sees. 67 and 69). 
 If the water of any well or cistern is deemed to be injurious to 
 health, a justice's order may be obtained for its being permanently 
 or temporarily closed, or the water to be used for certain purposes 
 only, and for the payment of any necessary analysis of the sample 
 at the cost of the S.A. (sec. 70). 
 
 The general provisions of the P.H.A., 1875, m respect of 
 water supply may be briefly summarized by saying that it is the 
 duty of the S.A. to provide their district with water, where danger 
 exists to the health of the inhabitants from either the unwhole- 
 someness or the insufficiency of the existing supply, and a proper 
 supply can be got at reasonable cost. If the S.A. neglect to do 
 this duty, the same proceedings can be taken to make them 
 perform it under sec. 299 of the Act of 1875, or, if they are 
 a rural sanitary authority, under the L.G A., 1894, sees. 16 and 
 19, just as can be taken in the case of their failing to supply the 
 district with sewers. But cases arise where it is impossible for 
 the S.A. to supply water at a reasonable cost; under these cir- 
 cumstances they may require the owner to do so, if he can at 
 reasonable cost (P.H. (Water) A., 1878, sec. 3). If neither the 
 S.A. nor the owner can provide water at a reasonable cost, then, 
 if the absence of a proper water supply creates a nuisance that the 
 
WATER SUPPLY. 469 
 
 house is unfit for habitation, steps may be taken to obtain a 
 justice's order prohibiting its being so used for human habitation 
 (P.H. A., 1875, sec. 97)/ 
 
 It was largely to meet difficulties of this kind, especially in 
 rural districts, that the P.H. (Water) A. of 1878 was designed. 
 It applies to every rural sanitary authority, and also to such 
 urban authorities as the M.H. may order (sec. 11). Under 
 sec. 3 of this same Act, it is the duty of the local authority 
 to provide or require the provision of sufficient water supply 
 to every occupied dwelling-house within their district. From 
 time to time they may take steps, by means of inspections 
 on the part of their officers, to see that these conditions are 
 fulfilled. The same powers of entry upon premises are given as 
 are conferred by sees. 102 and 103, P.H. A., 1S75, in respect of 
 nuisances (sec. 7) ; and if the M.O.H. reports that an occupied 
 house is without a proper water supply, and the S.A. are of 
 opinion that such a supply can be provided at a reasonable cost 
 (the interest on which at 5 per cent, shall not exceed twopence 
 a week, or as the M.H. may, on the application of the S.A., 
 decide to be reasonable in the circumstances), the S.A. may 
 require the owner, subject to appeal to the M.H., to provide 
 such supply within a specified time, and in case of default may 
 themselves carry out the necessary works at his expense. The 
 authority may, on cause being shown why the requirements of 
 the notice served by them should not be complied with, withdraw 
 the notice or modify the terms thereof. Nothing, however, in 
 this Water Act must be deemed to relieve the S.A. from the duty 
 imposed upon them by the P.H. A., 1875, of providing their 
 district or any contributory part of it with a supply of water, 
 where danger arises to the health of the inhabitants from the 
 insufficiency or unwholesomeness of the existing supply, and a 
 general scheme pf supply is required, and can be got at a reason- 
 able cost (sees. 3 and 4). 
 
 In order to prevent houses being built in situations where 
 they cannot be provided with water, the W^ater Act, 1S78, has 
 prohibited (sec. 6) the owner oi any dwelling in a rural district 
 that may be erected or rebuilt from the ground floor after July 4, 
 1878, from permitting such house to be occupied without a 
 certificate from the S.A. that it is provided with a sufficient and 
 available supply of wholesome water ; such certificate to be based 
 upon the report of the M.O.H. or sanitary inspector. Sec. 9 
 of the same Act provides that if the S.A. furnish a stand-pipe for 
 water supply, they may make water-charges upon every dwelling 
 within 200 feet, just as if the supply were actually given on the 
 premises; but they may not make this levy upon houses which 
 
470 SANITARY LAV/. 
 
 have a good supply within reasonable distance, from another 
 source, unless the water from the stand-pipe is used by the 
 inmates. 
 
 The L.G.A., 1894, sec. 8 (1) (e), empowers a parish- council 
 to utilize any well, spring, or stream within the parish, and to 
 provide facilities for obtaining water therefrom, consistent with the 
 just rights of any person or corporation ; but these powers do not 
 in any way derogate from the obligations of a rural sanitary 
 authority in respect of supplying water. 
 
 Under the Rivers Pollution Prevention Act, 1876, proceedings 
 may be instituted, in respect of pollution of streams by sewage or 
 solid matters, by any private person or aggrieved local authority 
 (sec. 8) ; but in respect of manufacturing or mining effluents, a 
 S.A. only can take action, and that subject to the approval of the 
 M.H. The Ministry, in giving or withholding consent, must have 
 regard to the industrial interests involved, and the circumstances 
 and requirements of the locality. They shall not give their con- 
 sent to proceedings by a S.A. of a district which is the seat of any 
 manufacturing industry, unless they are satisfied, after due inquiry, 
 that means for rendering harmless the effluents from such manu- 
 facturing processes are reasonably practical and available, and 
 that no material injury to the interests of such industry will be 
 caused by the proceedings (sec. 6). These powers are capable of 
 further amplification by the formation of River Boards, composed 
 of joint Committees of County Councils, for the purpose of better 
 enforcement of the R.P.P.A. Sec. 14 of the L.G.A., 1888, confers 
 upon County Councils the powers of S.A. under the R.P.P.A., and 
 enables the M.H. to form joint Committees of administrative 
 Counties through which a river or part of a river passes. Such a 
 joint Committee has all or any of the powers of a S.A. under the Act. 
 
 The water supply of the Metropolis is now in the hands of the 
 Metropolitan Water Board. This Board controls the water supply 
 not only in London, but also over a large extra-metropolitan area. 
 Practically the Board has the same position as the provincial 
 water companies, and so far as this question is concerned neither 
 the county council nor any other local authority in London has 
 any direct power. The controlling authority, as atfecting the 
 public health, over the water board is the M.H., who have 
 the water supplied examined periodically, approve or disapprove 
 of new sources of supply, of various regulations made by the 
 board for preventing waste, misuse, or contamination, and who 
 also inquire into complaints made to them as to the quality or 
 quantity of the water supplied for domestic use. 
 
 The Metropolis Water Act gives the County Council power 
 to ask for the repeal or alteration of any of the regulations for 
 
WATER SUPPLY. 47 1 
 
 the above purposes, and if the board refuse to do so, to appeal 
 to the M.H., who, on inquiry and report of some impartial 
 engineer or person of engineering knowledge, may make such 
 repeal or alterations as they think fit. The same Act contains 
 similar provisions as to the county council asking for a constant 
 supply in any given district. The board cannot, however, be 
 compelled to give a constant supply to any premises in any 
 district until its regulations, as approved by the M.H., are in 
 operation in the district, nor if the board can show that at any 
 time after two months from the date of the service of any requi- 
 sition for a constant supply more than one-fifth of the premises 
 in the district are not supplied with the prescribed fittings. The 
 county 'council have power to supply the prescribed fittings on 
 default of owner or occupier. The M.H. have power to order 
 a constant supply without application from the county council 
 where they think that by reason of the insufficiency of the existing 
 supply in the district, or the unwholesomeness of such water in 
 consequence of its being improperly stored, the health of the 
 inhabitants is, or is likely to be, prejudicially affected. 
 
 So far as relates to the powers of the metropolitan boroughs 
 and borough councils in connection with the water supply, the 
 P.H. (Lond.) A., 1891, indicates the absence of a proper water 
 supply or of proper fittings in a house, to render such house unfit 
 for habitation. A new house must not be occupied until the S.A. 
 grant a certificate that it has a proper water supply (sec. 48). The 
 water board cutting off the supply of water to any house, must 
 give immediate notice to the S.A. (sec. 49). For the closure of 
 polluted wells, etc., the S.A. have only to satisfy a justice that the 
 water is " so polluted or likely to be so polluted, as to be injurious 
 or dangerous to health" (sec. 54). It must be noted that this 
 section gives a S.A. somewhat greater powers than sec. 70, 
 P.H. A., 1875, inasmuch as it says not only when the water is 
 so polluted as to be injurious to health, but when it is so polluted 
 or likely to be so polluted as to be injurious or dangerous to health. 
 Moreover, it gives the court no power to allow the water to be 
 used for certain purposes only, and imposes a fine not exceeding 
 ^20 for disobedience to any order under this section. 
 
 Every S.A. under the London Act of 1891 must make bye-laws 
 for cleansing tanks, cisterns, and other receptacles for storing 
 water likely to be used for drinking or domestic purposes, and 
 guarding them from pollution (sec. 50). The model bye-laws 
 framed in connection with this section, demand: (i)the emptying 
 and cleansing of cisterns and tanks once at least in every six 
 months, and at such other times as may be necessary to keep 
 them clean ; (2) every such tank, cistern, or receptacle to be 
 
472 SANITARY LAW. 
 
 fitted with a proper cover, and to be kept at all times properly 
 covered. In cases where two or more tenants of a premises are 
 entitled to the common use of any tank, cistern, or receptacle to 
 which this bye-law applies, the foregoing requirements apply to 
 the owner instead of to the occupier of the premises. 
 
 Nuisances. — In a legal sense, nuisances are of two chief 
 kinds, namely, (i) nuisances at common law, (2) nuisances under 
 the Public Health Acts, commonly called " statutory nuisances." 
 
 Statutory nuisances have been well defined by Wynter-Blyth 
 as being "something which either actually injures, or is likely to 
 injure health, and admits of a remedy, either by the individual 
 whose act or omission causes the nuisance, or by the local 
 authority." In the Public Health Act sense, as now understood 
 and interpreted, the idea of a nuisance embraces future as well as 
 present consequences. The sanitary law in respect of nuisances 
 may be summarized in the following manner. 
 
 The provisions of the P.H.A., 1875, sees. 91 to in, dealing 
 with nuisances, apply to every urban and rural sanitary district, 
 and are " deemed to be in addition to, and not to abridge any 
 right, remedy, or proceeding under any other provisions of the 
 Act, or under any other Act, or at law or in equity." But no 
 person may be punished for the same offence both under these 
 provisions and under any other law or enactment. Under this 
 1875 Act "nuisance" is regarded as likely to arise in connection 
 with: (a) sewers, sees. 18, 19 ; (b) sewage, sec. 27; (c) con- 
 struction of drains, closets, ash-pits, and cesspools, sees. 40, 41 ; 
 by the P.H.A. (Amend.) A., 1907, nuisances under this head 
 embrace cisterns, gutters, drains, shorts, stack pipes, and deposits of 
 material in or on any building or land which shall cause damp in 
 any such building; (d) in connection with snow, dust, ashes, filth, 
 and rubbish, sec. 44; (e) swine, pigsties, and stagnant water in 
 cellars, or the overflowing of privies and cesspools, sec. 47 ; (f) 
 offensive trades, sees. 112, 113, and 114. 
 
 In regard to some of these cases, remedies are given by other 
 provisions of the Act, more particularly by sees. 41, 49, and 
 50. It will rest with a S.A. to determine under which provisions 
 they will proceed. The main section dealing with nuisances is, 
 however, sec. 91, which defines the following to be nuisances 
 to be dealt with summarily under the Act : (1) Any premises, 
 including buildings and lands, in such a state as to be a nuisance 
 or injurious to health. (2) Any pool, ditch, gutter, watercourse, 
 privy, urinal, cesspool, drain, or ash-pit, so foul, or in such a state 
 as to be a nuisance or injurious to health. (3) Any animal so 
 kept as to be a nuisance or injurious to health. (4) Any accumu- 
 lation or deposit which is a nuisance or injurious to health. 
 
NUISANCES. 473 
 
 (5) Any house, or part of a house, so overcrowded as to be 
 dangerous or injurious to health of the inmates, whether or not 
 members of the same family. (6) Any factory, workshop, or 
 work-place, not kept in a cleanly state, or not ventilated in such 
 a manner as to render harmless as far as practicable any gases, 
 vapours, dust, or other impurities generated in the course of the 
 work carried on therein that are a nuisance or injurious to health, 
 or so overcrowded as to be dangerous or injurious to the health 
 of those employed therein. (7) Any fireplace or furnace which 
 does not, as far as practicable, consume the smoke arising from the 
 combustible used therein, and which is used for working engines 
 by steam, or in any manufacturing or trade process whatever • and 
 any chimney (not being the chimney of a private dwelling-house) 
 sending forth black smoke in such quantity as to be a nuisance. 
 
 In defining these nuisances, the same section, however, 
 provides that there is no penalty if the accumulation or deposit 
 mentioned in (4) is necessary for, and has not been kept longer 
 than is necessary for the carrying on of any business or manu- 
 facture, and if the best available means have been taken for 
 preventing injury to the public health. The provisions of sub- 
 section (6) apply to all buildings, including schools, factories, and 
 workshops, except such as are subject to the special provisions, 
 relating to cleanliness, ventilation, or overcrowding, of the 
 Factories and Workshops Acts. In respect of (7), there is no 
 penalty if the Court is satisfied that the fireplace or furnace is 
 constructed in such manner as to consume, as far as practicable, 
 having regard to the nature of the manufacture or trade, all 
 smoke arising therefrom, and that such fireplace or furnace has 
 been carefully attended by the person in charge thereof. Under 
 the smoke sections, it is not necessary in taking action to prove 
 anything with regard to health, it being sufficient to prove that on 
 such and such a day and hour the chimney emitted black smoke. 
 Urban sanitary authorities have some other powers with regard to 
 smoke under sec. 171 of this Act, and under the Railway 
 Regulation Act, 1868, and the Highways and Locomotives Act 
 of 1878. 
 
 For interpreting the term "overcrowded" in sec. 91 (5), 
 P.H.A., 1875, a sanitary officer usually takes as his guide the 
 minimum standards laid down by the model bye-laws, namely, 
 400 cubic feet for rooms in which persons both live and sleep, 
 and 300 cubic feet for rooms used solely for the waking life of the 
 tenants. For factories and workshops, by the F.W.A., 1895 an ^ 
 1901, overcrowding is deemed to exist when the cubic space for 
 adults is less than 250 cubic feet, and 400 cubic feet during over- 
 time. In the event of a second conviction for overcrowding 
 
474 SANITARY LAW. 
 
 within three months, the Court may order the closing of the 
 premises (P.H.A., 1875, sec. 109). Another point to be noted in 
 connection with sec. 91 (5) of the 1875 Act, is that the* words 
 " tent, van, shed, or similar structure" may be included within 
 it by sec. 9 of the Housing of the Working Classes Act, 1885. 
 
 Unfenced quarries and abandoned coal-mines are deemed to 
 be nuisances under sec. 91, P.H.A., 1875, by the Quarry Fencing 
 Act, 1887, and by the Coal Mines Regulation Act, 1887. 
 
 It is the duty of every S.A. to cause their district to be 
 inspected for the detection of nuisances, and to enforce the 
 provisions of the P.H.A., 1875, in order to abate the same 
 (sec. 92), but the authority may be put in motion by any 
 aggrieved person, or by any two inhabitants of such district, or by 
 any officer of the S.A., or by the relieving officer, or by any 
 police officer (sec. 93). If satisfied of the existence of a nuisance, 
 the S.A. is required by the Act to serve a notice on the person 
 responsible, or, if he cannot be found, on the owner or occupier 
 of the premises on which the nuisance arises, requiring him to 
 abate the same within a time to be specified in the notice, and to 
 execute such works as are specified in the notice to be necessary. 
 When the nuisance arises from the want or defective construction 
 of any structural convenience, or where there is no occupier, the 
 notice must be served on the owner. If the person causing the 
 nuisance cannot be found, and the owner or occupier is not 
 responsible for its occurrence, the S.A. may themselves abate the 
 same without further order (sec. 94). On non-compliance with the 
 notice, or if the nuisance, although abated, is likely to recur, 
 the S.A. may apply to a justice, who must thereupon summon 
 the person responsible to appear before a court of summary 
 jurisdiction (sec. 95). If the Court is satisfied that the alleged 
 nuisance exists, or that although abated, it is likely to recur on 
 the same premises, it must make an order requiring him to 
 comply with the notice, or prohibiting the recurrence of the 
 nuisance, and directing the execution of any necessary works. 
 The Court may further impose a penalty not exceeding ^5 
 (sec. 96). Where the nuisance is such as to render the house 
 unfit for habitation, the Court may order the house to be closed, 
 and may cancel this by a further order when satisfied that the 
 house has been made fit for habitation (sec. 97). Any person 
 not obeying the order of the Court, or failing to use diligence, is 
 liable to a penalty not exceeding ten shillings per day during his 
 default, and the S.A. may carry out the order and charge him 
 with the expenses (sec. 98). Where the person responsible for 
 the nuisance cannot be found, the order of the Court may be 
 carried out by the S.A. ; and any matter or thing removed by the 
 
NUISANCES. 475 
 
 authority in abating any nuisance may be sold (sees, ioo, 101). 
 Where any nuisance under the Act is caused by the acts or 
 defaults of two or more persons, the S.A. may institute proceed- 
 ings against any one or more of such persons (sec. 255). Where 
 a nuisance within a district is caused by some act or default 
 beyond its limits, the S.A. may institute proceedings provided 
 that they be taken before a court having jurisdiction in the 
 district where the act or default is alleged to be committed or 
 take place (sec. 108). 
 
 For the purpose of the provisions of this Act of 1875, relating 
 not only to nuisances, but also for infectious diseases and hospitals, 
 any ship or vessel lying in any water within the district of a sanitary 
 authority is subject to their jurisdiction, as if it were a house. If 
 in any other water, it is deemed to be within such district as the 
 M.H. may prescribe, and in the absence of any such prescription, 
 then within the nearest sanitary district (sec. no). The master 
 or other officer in charge of any such ship will be deemed to be 
 the occupier; but these provisions do not apply to any of His 
 Majesty's ships, or to those of any foreign government. 
 
 The S.A. and their officers have rights of entry between 9 a.m. 
 and 6 p.m. upon private premises, and in the case of a nuisance 
 arising in respect of any business, at any hour when such business 
 is in progress. If admission is refused, a justice's order may be 
 obtained (sees. 102, 103). 
 
 Where sanitary authorities fail to take proceedings for abate- 
 ment of nuisances, individuals may obtain a remedy in one of 
 three ways, either (1) by complaining to the M.H., who may 
 issue an order, enforceable by mandamus in a High Court (sec. 
 299) ; or (2) on it being proved to the satisfaction of the M.H. 
 that a S.A. has made default in relation to nuisances under the 
 P.H.A., 1875, tne Ministry may authorize any police officer, 
 acting within the district of the defaulting authority, to institute 
 proceedings, which the defaulting authority might institute with 
 regard to such nuisance (sec. 106); or (3) an individual may 
 complain direct to a justice as to the existence of a nuisance, and 
 the Court may make orders, penalties for disobedience of orders, 
 etc., as in the case of a complaint relating to a nuisance made to 
 a justice by a S.A. (sec. 105). This latter mode of procedure is obvi- 
 ously the most expeditious for any individual to take where he feels 
 aggrieved by the neglect of a S.A. to take proceedings, and where 
 the existence of a nuisance within the meaning of the Act is 
 clear. 
 
 Under the P.H. (Lond.) A., 1S9T, and the L.G.A., 1899, the 
 powers and duties of the borough councils in the capacity of sani- 
 tary authorities in London, with respect to nuisances, correspond 
 
476 SANITARY LAW. 
 
 in the main with those already detailed as applicable to sanitary- 
 authorities in England and Wales under the Act of 1875. The 
 London Act embodies, however, several amendments and exten- 
 sions of the law which have materially strengthened the hands of 
 the Metropolitan sanitary authorities for dealing with nuisances. 
 Sec. 2 of the London Act extends the definition of " nuisance," 
 making it include not only that which is i?ijurious to health, but 
 also that which is dangerous to health. It also makes it include 
 any cistern, water-closet, earth-closet, or dung-pit, so foul or in 
 such a state as to be a nuisance or injurious, or dangerous to 
 health, and any such absence from premises of water fittings as 
 is a nuisance by virtue of sec. 3 of the Metropolitan Water Act, 
 187 1. Further, any person may give information to the S.A. of a 
 nuisance, and it is the duty of every officer of the authority and of 
 the relieving officer so to do, and to give written notice to the 
 persons who may be required to abate it 
 
 In giving notice requiring abatement of a nuisance, it is 
 optional to specify the works to be executed; also, where the 
 person responsible for causing the nuisance cannot be found, the 
 S.A. may not only themselves abate the nuisance, but also do 
 what is necessary to prevent its recurrence. In cases of over- 
 crowding, the S.A. must take proceedings to abate the nuisance. 
 The penalty for wilful nuisance or non-abatement is a fine of ^10 
 for each offence, whether an order to abate it or prohibiting its 
 recurrence is made or not (P.H. (Lond.) A., 1891, sec. 4). 
 
 Similarly, the maximum fines for failing to comply with an 
 order for the abatement of a nuisance, or for acting contrary to 
 a prohibition order, are increased from the amounts fixed by the 
 P.H.A., 1875, to 20J-. a day, and 40J. a day respectively, during 
 default or contrary action, as the case may be (sec. 5 (9)). Wilful 
 damage to drains, water-closets, etc., so as to create nuisances, 
 involve a fine not exceeding ^5 (sec. 15). Groundless appeals 
 to quarter sessions against nuisance orders are checked by daily 
 fines of 2 0J-. (sec. 6 (3) (4)). 
 
 The S.A., moreover, is required by sec. 16 of the London 
 Act to make bye-laws for the prevention of nuisances arising from 
 (1) any snow, ice, salt, dust, ashes, rubbish, offal, carrion, fish, 
 filth, or other matter in the street ; (2) from any offensive matter 
 running out of any manufactory, brewery, slaughter-house, knacker's 
 yard, butcher's or fishmonger's shop, or dunghill, into any un- 
 covered place, whether or not surrounded by a wall or fence; 
 (3) from keeping of animals ; (4) as to the paving of yards and 
 open spaces in connection with dwelling-houses. It is, moreover, 
 the duty of the S.A. to enforce any bye-laws made, in respect of 
 these matters, by the county council. 
 
UNSOUND FOOD. 477 
 
 Under the L.G.A. (Lond.), 1899, it is the duty of each borough 
 council to enforce within their borough the bye-laws and regula- 
 tions for the time being in force with respect to dairies and milk, 
 and with respect to slaughter-houses, knackers' yards, and offensive 
 businesses, and for the purpose of performing this duty, the 
 borough council shall in all cases have the same powers of entry 
 as was accorded under the P.H.A. (Lond.), 1891. 
 
 As regards the prevention of smoke in London, sec. 24, 
 P. PI. (Lond.) A., 189 1, corresponds closely with sec. 91 of the 
 1875 Act; but the main provisions against nuisances arising 
 from smoke in the Metropolis are contained in sec. 23 of the 
 London Act, which provides that " every furnace employed in the 
 working of engines by steam, and every furnace employed in any 
 public bath or wash-house, or in any mill, factory, printing-house, 
 dye-house, iron-foundry, glass-house, distillery, biew-house, sugar- 
 refinery, bake-house, gasworks, waterworks, or other building used 
 for the purpose of trade or manufacture (although a steam-engine 
 be not used or employed therein), shall be constructed so as to 
 consume and burn the smoke arising from such furnace." Sanitary 
 authorities must carry out these provisions of this section, and, 
 moreover, any information under it is not to be laid except under 
 the direction ot a S.A. This section extends to the port of 
 London, where it must be enforced by the port sanitary authority, 
 which is the City Corporation. 
 
 Unsound Food.— Under the P.H.A., 1875, the M.O.H. and 
 inspector of nuisances have power, at all reasonable times, including 
 Sundays, to examine any animal, carcase, meat, poultry, game, 
 flesh, fish, fruit, vegetables, corn, bread, flour, or milk exposed for 
 sale, or deposited for the purposes of sale, or of preparation for 
 sale, and intended for the food of man ; and may seize the same 
 if diseased, unsound, or unwholesome, and take it to a magistrate 
 (sec. 116), who may order it to be destroyed or so disposed of as 
 to prevent it from being exposed for sale, or used for the food 
 of man, and inflict a penalty not exceeding ^"20, or a term of 
 imprisonment of not more than three months (sec. 117). The 
 proof that it was not intended for the food of man rests with 
 the person charged. Any person hindering these officers from 
 inspecting meat, etc., is subject to a penalty of ^5 (sec. 118). 
 On complaint made by oath by any officer of a S.A. that there is 
 reason to believe that there is kept or concealed on any premises 
 any articles to which these sections apply, a justice may grant a 
 search-warrant, and any person hindering the execution of this 
 warrant is liable to a penalty of ^20 (sec. 119). 
 
 Under sec. 4, S.F.D. A., 1899, the Board of Agriculture has the 
 power to fix the limit of deficiency from the normal in the com- 
 
478 SANITARY LAW. 
 
 position of milk, cream, butter, and cheese, and declare what 
 addition of extraneous matter thereto, or proportion of water 
 therein (including, as to the former, condensed milk), shall raise 
 a presumption that the article in question is not genuine, or is 
 injurious to health. Statutory orders under this section have been 
 issued, and have now the force of law. 
 
 By the Butter and Margarine Act, 1907, all butter and mar- 
 garine factories must be registered. It is an offence for any 
 substance for the adulteration of butter to be found in any butter 
 factory. Further, no butter or margarine may contain more than 
 16 per cent, of water, nor milk-blended butter more than 24 per 
 cent, of water. In the marking of wrappers, all margarine must 
 be described either as margarine or by a name embracing the 
 word " margarine " ; margarine means any article of food, whether 
 mixed with butter fat or not, which resembles butter and is not 
 milk-blended butter. It includes also " margarine-cheese." 
 Milk-blended butter must be sold under such name as may be 
 approved by the B.A., and the wrapper must set out the percent- 
 age of water contained therein and approved by the Board. The 
 brand or mark " margarine " or " margarine-cheese " must be on the 
 package itself and not solely on a label or ticket. The letters must 
 be half an inch long, legible, and with no other printed matter. 
 
 Proceedings for offences under the various Acts will have 
 to be taken in all cases within twenty-eight days from the date of 
 purchase ; the summons is to state the nature of the offence with 
 which the defendant is charged, and to be accompanied by a copy 
 of the analyst's certificate, and is not returnable for hearing until 
 after the expiration of fourteen days from the date of service 
 (sec. 19). 
 
 In markets and fairs under the control of a S.A., the sale of 
 unwholesome meat or provisions is subject to similar provisions 
 under sec. 15 of the Markets and Fairs Clauses Act, 1847, which 
 is incorporated with the P.H.A., 1875. Where the market or 
 fair does not belong to the local authority, the above provisions 
 will not apply, unless a local Act is in force, with which the 
 Market and Fairs Clauses Act is incorporated. A S.A. can make 
 bye-laws for preventing the sale of unwholesome provisions in 
 a market or fair by sec. 42 of the Act of 1847, also incorporated 
 in the P.H.A., 1875, but owing to the stringency of sees. 116 to 
 119 of this latter Act, these bye-laws will be rarely necessary. 
 
 The P.H. (Food Regulations) A., 1907, enables a S.A. to 
 make regulations for the prevention of danger arising to public 
 health from the importation, preparation, storage, and distribution 
 of food, in amplification of the power which such authority 
 possesses under the P.H. A., 1875. For the purposes of these 
 
UNSOUND FOOD. 479 
 
 regulations, articles commonly used for food or drink by man 
 shall be deemed to be intended for sale for human consumption, 
 unless the contrary be proved. 
 
 Two sets of Regulations have been issued under this Act, one 
 the "Unsound Food Regulations" of 1908, and the other the 
 " Foreign Meat Regulations" of 1908. Under these regulations 
 powers are, conferred on the M.O.H.or other authorized officer of 
 a S.A. to examine and seize any article of food which in his 
 opinion is unsound or unwholesome, in order that an application 
 be made to a justice for an order of condemnation. Similar 
 powers of inspection and seizure are given as to imported foreign 
 meat. An M.O.H. may pass the meat without further examina- 
 tion, if provided with an official certificate of soundness affixed 
 in the country of exportation. Foreign meat is graded into three 
 classes. Class I. comprises scrap meat, tripe, tongue or kidney 
 with antiseptics, and parts of uncured pig. Class II. is the 
 carcass of the pig uncured minus the head and lymphatic glands. 
 Class III. embraces severed u?icu?rd parts of the carcass of the 
 pig. " Unclassed " embraces all other foreign meat. 
 
 In the Metropolis, under sec. 47, P.H. (Lond.) A., 1891, the 
 provisions as to the sale of unsound food are somewhat more 
 stringent. The London Act not only closely follows the lines 
 of sec. 28, Part III., P.H. (Amend.) A., 1890, but renders the 
 offender liable, on conviction, to a fine not exceeding ^50, or 
 imprisonment for six months with or without hard labour. The 
 section further enforces the liability of the previous vendor of the 
 food, and also renders any one obstructing an officer acting under 
 a warrant for entry within twelve months after a previous conviction 
 for obstruction and evidently with intent to prevent detection, 
 liable to imprisonment for a month in lieu of fine. The S.A. have 
 further the duty placed upon them of removing unsound food, as 
 if it were trade refuse, on the receipt of w-ritten notice from a 
 person having possession of the same. 
 
 Horseflesh. — The provisions controlling the sale of horseflesh 
 for human food are the same in all parts of the United Kingdom. 
 They are contained in the Sale of Horseflesh, etc., Regulation 
 Act, 1889, which defines "horseflesh" to be horseflesh, cooked or 
 uncooked, alone or mixed with other substances, and includes the 
 flesh of asses and mules. 
 
 This Act provides that the flesh of horses, asses, or mules 
 must not be sold or kept for sale for human food, except in a shop 
 or stall over or upon which is placed in conspicuous and legible 
 characters 4 inches long, an announcement that horseflesh is sold 
 there. If otherwise, the M.O.H. or inspector of nuisances, or 
 any other officer of the S.A., may seize the meat and carry it 
 
480 SANITARY LAW 
 
 before a magistrate, who may order as to its disposal as he thinks 
 fit ; and the offender is liable to penalty. It is illegal to supply 
 horseflesh for human food to a purchaser asking for other meat, 
 or for a compound article not usually made of horseflesh. 
 
 Bakehouses. — Under the Factory and Workshop Act, T901, 
 considerable powers of sanitary control are given to district 
 councils over bakehouses. Sec. 97 prescribes the sanitary regula- 
 tions for bakehouses ; sec. 98 imposes a penalty for a bakehouse 
 being unfit for the purpose on sanitary grounds ; sees. 99 and 100 
 provide for the periodical lime washing, painting, etc., of these 
 places, and require proper regulation of sleeping accommodation 
 near bakehouses; sec. 101 prohibits underground bakehouses 
 except where they were so used at the passing of the Act, and 
 subject to the foregoing provision, after the first day of January, 
 1904, no underground bakehouse shall be used unless certified by 
 the district council to be suitable as regards construction, light, 
 ventilation, and in all other respects. No sleeping place is 
 allowed on same level as a bakehouse unless there be complete 
 separation and the sleeping room has an external window of 
 9 square feet, one half opening. No closet or ashpit is allowed 
 within or to communicate directly with a bakehouse ; neither may 
 there be a drain or pipe carrying faecal or sewage matter with an 
 opening within a bakehouse. Each bakehouse must have a 
 separate water cistern. An underground bakehouse means a 
 baking room so situate that the surface of the floor is more than 
 3 feet below the surface of the footway or nearest ground. Sec. 
 102 imposes on the district council the duty of enforcing these 
 provisions as to bakehouses. 
 
 Shellfish. — The P.H. (Shellfish) Regulations, 1915, issued 
 under the P.H. (Reg. as to Food) Act, 1907, provides machinery 
 for closing of shellfish layings, suspected or known to be in 
 polluted waters, where the evidence justifies such action by an 
 Order of the local S.A. The local authority of a district in which 
 the layings are situate must take action on representation from 
 another local authority in whose district the shellfish are consumed. 
 The closing of such shellfish layings is subject to appeal to the 
 Ministry of Health by either or all parties interested. 
 
 Milk Supplies. — It has already been shown that, under sec. 
 117, P.H.A., 1875, and under sec. 15, Market and Fairs Clauses 
 Act, 1847, unwholesome provisions, including milk, may be dealt 
 with by seizure and condemnation. The Acts, however, which 
 are most active in regulating the milk supply, are the CD. 
 (Animals) A., 1878 and 1886. Under these Acts the M.H. have 
 power to make general or special orders for (1) the registration 
 with the local authority of all persons carrying on the trade of 
 
MILK SUPPLIES. 4S1 
 
 cowkeepers, dairymen, or purveyors of milk ; (2) for the in- 
 spection of cattle in dairies, and the general sanitation of 
 dairies and cowsheds ; (3) for securing the cleanliness of 
 milk-stores, shops, and vessels for containing milk ; (4) for 
 guarding milk against infection; (5) and for authorizing local 
 authorities to make regulations for any or all of the aforesai4 
 purposes. 
 
 Under the powers thus conferred, were issued the Dairies, 
 Cowsheds, and Milk-shops Order of 1885, 1886, and 1899, the 
 chief effect of which Orders is to throw upon every S.A. the duty 
 of supervising the milk trade in their district, and of carrying 
 out certain general regulations prescribed by the Orders. These 
 duties are common to all districts, but any S.A. may arm itself 
 with further powers by making regulations under sec. 13 of the 
 Order of 1885, having the force of bye- laws. The chief provisions 
 of the Order of 1885, as amended by that of 1886, are summarized 
 as follows : — 
 
 Section 6. (1) It shall not be lawful for any person to carry 
 on in the district of any local authority the trade of cowkeeper, 
 dairyman, or purveyor of milk unless he is registered as such in 
 accordance with this article. (2) Every S.A. shall keep a register 
 of such persons, and shall from time to time revise and correct 
 the register. (3) The S.A. shall register every such person, but 
 the fact of such registration shall not be deemed to authorize 
 such person to occupy as a dairy or cowshed any particular 
 building, or in any way preclude any proceedings being taken 
 against him. (4) The S.A. shall from time to time give public 
 notice of registration being required, and of the mode of regis- 
 tration. (5) A person who carries on the trade of cow- 
 keeper or dairyman for the purpose only of making and 
 selling butter or cheese, or both, and who is not also a purveyor 
 of milk, need not be registered. (6) A person who sells milk 
 of his own cows in small quantities to his workmen or neigh- 
 bours for their accommodation need not, by reason thereof, be 
 registered. 
 
 Section 7. (1) It shall not be lawful to begin to occupy 
 as a dairy or cowshed any building not so occupied at the 
 commencement of this Order until provision is made, to the 
 reasonable satisfaction of the S.A., for the lighting and ventila- 
 tion, including air-space (800 cubic feet per head are suggested 
 as a minimum), and the cleansing, drainage, and water supply ; 
 (2) or without giving one month's notice in writing to the 
 sanitary authority. 
 
 Section 8. It shall not be lawful for any . . . cowkeeper or 
 dairyman to occupy as a dairy or cowshed any building, the lighting 
 
 R 
 
482 SANITARY LAW. 
 
 and ventilation, including air-space, and the cleansing, drainage, 
 and water supply thereof, are not such as are necessary or proper 
 for the health and good condition of the cattle therein ; and for 
 the cleanliness of milk vessels used therein for containing milk 
 for sale ; and for the protection of the milk therein against infection 
 or contamination. 
 
 . Section 9. It shall not be lawful for any cowkeeper, dairyman, 
 or purveyor of milk or occupier of a milk shop (a) to allow any 
 person suffering from a dangerous infectious disorder, or having 
 recently been in contact with a person so suffering, to milk cows 
 or handle vessels used for containing milk for sale, or in any way 
 to take part or assist in the conduct of the trade ... so far as 
 regards the production, distribution, or storage of milk; or (b) if 
 himself so suffering, or having recently been in contact as aforesaid, 
 to milk cows or handle vessels containing milk for sale, or in any 
 way to take part in the conduct of the trade as far as regards the 
 production, storage, and distribution of milk ; until in each case, 
 all danger therefrom of the communication of infection to the 
 milk, or of its contamination has ceased. 
 
 Section 10. It shall not be lawful for any cowkeeper, dairy- 
 man, or purveyor of milk, or occupier of a milk-shop or milk-store, 
 after the receipt of notice of not less than one month from the 
 local authority calling attention to the provisions of this Article, 
 to permit any water-closet, earth-closet, privy, cesspool, or urinal 
 to be within, communicate directly with, or ventilate into, any 
 dairy or room used as a milk-store or milk-shop. 
 
 Section 11. It shall not be lawful for any cowkeeper, dairy- 
 man, or purveyor of milk, or occupier of a milk-shop or milk-store, 
 to use a milk-shop or store in his occupation, or permit the same 
 to be used, as a sleeping apartment, or for any purpose in- 
 compatible with the proper preservation of the cleanliness of 
 the milk-store or shop, and of the milk vessels and milk therein, 
 or in any manner likely to cause contamination of the milk 
 therein. 
 
 Section 12. It shall not be lawful for any cowkeeper, dairy- 
 man, or purveyor of milk to keep any swine in any building used 
 by him for keeping cows, or in any milk-store or other place used 
 by him for keeping milk for sale. 
 
 Section 13. Any S.A. may from time to time make regula- 
 tions for the following purposes, or any of them : — (a) For the 
 inspection of cattle in dairies ; (b) for prescribing and regulating 
 the lighting, ventilation, cleansing, drainage, and water-supply 
 of dairies and cowsheds; (c) for securing the cleanliness of 
 milk-stores, milk-shops, and milk-vessels used for containing 
 milk for sale; (d) for prescribing precautions to be taken by 
 
MILK SUPPLIES. 48 
 
 •-1 
 
 purveyors of milk, and persons selling milk by retail, against 
 infection or contamination. 
 
 Section 14. The following provisions shall apply to regulations 
 made by any S.A. under this Order : — (1) Every regulation shall 
 be published by advertisement in a newspaper circulating in the 
 district of the S.A. (2) The S.A. shall send to the M.H. a copy 
 of every regulation made by them not less than one month before 
 the date named for such regulation to come into force. (3) If at 
 any time the M.H. are satisfied on inquiry, with respect to any 
 regulation, that the same is of too restrictive a character, or other- 
 wise objectionable, and direct the revocation thereof, the same 
 shall not come into operation, or shall thereupon cease to operate, 
 as the case may be. 
 
 Section 1 5. The milk of a cow suffering from tuberculosis of 
 the udders, cattle-plague, pleuro-pneumonia, or foot-and-mouth 
 disease (a) shall not be mixed with other milk ; and (b) shall not 
 be sold or used for human food ; and (c) shall not be sold or used 
 for food of animals, unless it has been boiled. 
 
 The Amending Order of 18S6 imposed penalties of ^5 for 
 every offence, and in the case of continuing offences, an additional 
 daily penalty of 40^. The courts have power to reduce these 
 penalties if they think fit. 
 
 For the purpose of enforcing orders made under the CD. 
 (Animals) A., 1 878-1 886, the S.A. and its officers have the same 
 right of entry as they have under P.H.A., 1875, sec. 102, in respect 
 of nuisances. 
 
 As regards the metropolis, the P.H. (Lond.) A., 1891, which 
 repeals, so far as they apply to London, sec. 34 of the CD. 
 (Animals) A., 1878, and sec. 9 of the 1886 Act, gives the same 
 powers as are given by those sections to sanitary authorities in 
 the provinces, to the county council and the Corporation of 
 London to make bye-laws applicable to so much of the adminis- 
 trative county of London as is not included in the City, and in 
 the City respectively. The powers of the M.H. to make regula- 
 tions and orders for dairies are the same in the Metropolis as 
 elsewhere in England and Wales. The L.CC. under their 
 General Powers Act, 1907, can take milk samples for examination 
 for the presence of tubercle bacilli. If found, power is granted 
 for examination of cows, and cause shown by the dairyman why 
 prohibition of sale be not enforced. Every dairyman selling 
 milk within the County of London must notify the presence of 
 tuberculosis among his cows. 
 
 Where the P.H. A. (Amend.) A., 1907, is adopted, by sec. 52 
 of that Act, if an M.O.H. suspects that a milk supply is the cause 
 of infectious disease, the S.A. can call upon the person supplying 
 
484 SANITARY LAW. 
 
 the milk to furnish a list of places from which he derives such 
 supply. Further, in districts in which sec. 4 of I.D.P.A., 1890, 
 is in force, an M.O.H. can prohibit the sale of milk from suspected 
 dairies and, if authorized by a justice having jurisdiction within 
 the place where the dairy is situate, visit and inspect dairies with- 
 out his district and, if accompanied by a veterinary officer, can 
 inspect the animals. If after inspection he is of opinion that 
 infectious disease is caused by the consumption of the milk on 
 report to his S.A. that body can give 24 hours' notice to the dairy- 
 man to appear before them and show cause why the supply of 
 milk in their district should not be prohibited. If he fail to show 
 cause, they may order accordingly, notifying to the S.A. and C.C. 
 of the district in which the dairy is situate, and also to the M.H. 
 The order must be withdrawn on the S.A. being satisfied that the 
 milk supply has been changed, or that the cause of infection has 
 been removed. 
 
 The foregoing legislative enactments as to the control of 
 milk supplies are likely to be superseded by more drastic Orders 
 issued by the M.H. under the Milk and Dairies Acts, 19 15 and 
 1920. These Acts are not yet operative, but come into force 
 on a date to be appointed by the M.H. The Acts repeal the 
 CD. (A,) A., 1878 and 1886, also sections 9 and n of the 
 S.F.D.A., 1899. The provisions and scope of these new Milk 
 and Dairies Acts of 1915 and 1920 are extensive and embrace 
 the following features. The M.H. may make general or special 
 Orders as they think fit relating to registration of dairies and 
 dairymen with the S.A. ; licensing of dairymen by a S.A. ; the 
 inspection of dairies, persons employed and cattle by officers of 
 the S.A. ; the lighting, ventilation, cleansing, drainage, and water 
 supply of dairies ; the cleanliness of milk stores, milk shops, 
 and milk vessels ; the protection of milk from contamination ; 
 the prevention of the sale of infected or dirty milk or milk 
 products ; the cooling, conveyance, and distribution of milk ; 
 the labelling, marking, sealing, or closing of churns and vessels ; 
 the prevention of the adulteration of milk ; the conditions under 
 which milk designated " certified milk " may be sold ; the 
 authorization of regulations by a S.A. for these purposes, subject 
 to such conditions as the M.H. prescribes. 
 
 Any Orders issued by the Minister of Health must be con- 
 curred in by the Minister of Agriculture and Fisheries and also 
 be laid before both Houses of Parliament. 
 
 Sec. 1 (2) authorizes the person making an inspection of 
 cattle to require any cow to be milked from any particular teat 
 in his presence and to take a separate sample from any teat. 
 By sees. 2 and 3, the M.O.H. of a county or county borough, 
 
MILK SUPPLIES. 4S5 
 
 and, by Order of the M.H., of any S.A. for an area within a 
 county, if of opinion that tuberculosis is caused, or is likely to 
 be caused, by the consumption of milk supplied by any dairy 
 in which cows are kept within such county, county borough, or 
 S.A. or area within a county, may put in force the procedure for 
 stopping the supply of milk as is given in the first schedule of 
 the Act. This procedure is identical practically with that laid 
 down in Infectious Diseases Prevention Act, 1890. Further, if 
 the M.O.H. of any S.A. has reason to suspect that tuberculosis is 
 likely to be caused by any milk which is sold within his district, 
 he shall endeavour to ascertain the sources of supply, and give 
 notice of any facts ascertained to the M.O.H. of the county or 
 county borough in which the cows from which the milk is 
 obtained are kept. On receipt of such notice, the county or 
 county borough M.O.H. shall cause the cattle in the dairy to 
 be inspected. The results of such inspection, with copies of 
 bacteriological and veterinary reports must be sent to the M.O.H. 
 who gave notice, together with an account of any action taken 
 (sec. 4). 
 
 By sec. 5 it is an offence under the Act to sell or offer 
 for sale any milk from a cow which has tuberculosis, acute 
 mastitis, suppuration of the udder, anthrax, foot and mouth 
 disease, or actinomycosis of the udder, if it is proved that the 
 seller knew, or by exercise of ordinary care could have ascer- 
 tained, that the cow was so suffering. Sections 6 and 7 lay 
 down that milk sold in the streets from vehicles or recep- 
 tacles must be sold only from vehicles and receptacles on 
 which the vendor's name and address are conspicuously in- 
 scribed. Receptacles for the sale of condensed, machine skimmed, 
 or skimmed milk must be clearly so labelled. Powers as to 
 taking of samples under the Act by officers of the S.A. are 
 laid down in sec. 8, and sec. 9 amends the provisions of the 
 S.F.D.A., 1875 and 1907, as to procedure in the taking of milk 
 samples and subsequent proceedings in connection therewith. 
 The details as to procedure are given in the section of this 
 chapter dealing with adulteration of food. The appointment of 
 veterinary inspectors under the Act, and Orders made under it, 
 are provided for in sec. 10. 
 
 Sec. 12 is quite a new departure in that it enables a S.A., with 
 the approval of the M.PL, to establish and maintain milk depots, 
 also to purchase and sell milk at cost price within their area, 
 make and sell milk products, distribute, store, cool, clean, and 
 otherwise treat milk in their area. The S.A. can exercise any 
 such powers either itself or through the agency of any organiza- 
 tion approved by them, also with the consent of any other 
 
486 SANITARY LAW. 
 
 S.A. it may exercise these powers in the area of such other 
 S.A. 
 
 Sec. 13 provides that the M.H., after local inquiry, may 
 make an order, enforceable by mandamus, compelling a defaulting 
 local authority to perform its duties under the Act ; or in the case 
 of a district council, all its powers under the Act and Orders may 
 be transferred to the county council. Sec. 15 allows a S.A. to 
 delegate to a committee any of their powers or duties (other than 
 raising rates) under the Act or Orders. At least one-third of the 
 members of the committee shall be members of or elected by any 
 agricultural committee appointed by a local authority having 
 jurisdiction in their area or otherwise be representative of the 
 interests of agriculture. 
 
 The Act applies also to London, and its powers, otherwise 
 conferred on a S.A. with respect to the supply and distribution of 
 milk, are exercisable by the London County Council ; but if the 
 L.C.C. fail to exercise such powers, it is lawful for a S.A. in the 
 county to undertake the same, and the M.H., in approving any 
 scheme submitted for the purpose, may require the possible sub- 
 sequent reversion of the powers to be left open to be taken over 
 by the L.C.C. should such be deemed advisable. The Act 
 repeals sec. 20 of the P.H. (Lond.) A., 1891, so far as it relates 
 to dairymen, cowhouses, and places for keeping cows, also sub- 
 section (4) of sec. 6 of London Government Act, 1899, as relating 
 to dairies and milk, and also sec. 5 of the L.C.C General Powers 
 Act, 1908. These repeals only come into force from date when 
 a milk and dairies Order providing for the licensing of dairies 
 and dairymen comes into force. 
 
 The expression " dairy " in the Milk and Dairies Acts, 191 5 
 and 1920, includes any farm, cowshed, milk store, milk shop, or 
 other place from which milk is supplied on, or for sale, or in 
 w r hich milk is kept or used for purpose of sale or manufacture 
 into butter, cheese, dried milk, or condensed milk for sale ; and, 
 in the case of a purveyor of milk who does not occupy any 
 premises for the sale of milk, includes the place w r here he keeps 
 the vessels used by him for the sale of milk, but does not include 
 a shop from which milk is not supplied otherwise than in the 
 properly closed and unopened receptacles in which it was 
 delivered to the shop, or a shop or other place in w r hich milk 
 is sold for consumption on the premises only. The expres- 
 sion " milk ' : includes cream, skimmed milk, and separated 
 milk. 
 
 Adulteration of Food. — The legislative enactments relating 
 to this matter, in respect of the whole United Kingdom, are con- 
 tained in the Sale of Food and Drugs Act, 1875, tne Sale of Food 
 
ADULTERATION OF FOOD. 487 
 
 and Drugs Act Amendment Act, 1879, tne Margarine Act, 1887, 
 and Butter and Margarine Act, 1907, the Sale of Food and Drugs 
 Act, 1899,. and, so far as concerns England and Wales, also the 
 Local Government Act, 1888. As affecting milk and milk 
 products important provisions are contained in the Milk and 
 Cream Regulations of 19 12 and 191 7, and the Milk and Dairies 
 Act, 19 1 5 and 1920. These latter Acts are in abeyance at present. 
 
 The S.F.D.A., 1899, defines " food " as including every article 
 used for food or drink by man, other than drugs or water, and 
 any article which ordinarily enters into or is used in the com- 
 position or preparation of human food, and shall also include 
 flavouring matters and condiments; and "drug" as including 
 medicine for external as well as internal use. The S.F.D.A., 1875 
 (sec. 2), enacts that " no person shall mix, colour, stain, or powder 
 (or order or permit any other person to mix, colour, stain, or 
 powder) any article of food with any ingredient or material so as 
 to render the article injurious to health, with intent that the same 
 may be sold in that state ; and no person shall sell any article so 
 mixed, coloured, stained, or powdered . . ." (sec. 3). ' " No person 
 shall, except for the purpose of compounding, . . . mix, colour, 
 stain, or powder (or permit any other person to mix, colour, stain, 
 or powder) any drug with any ingredient or material so as to affect 
 injuriously the quality or potency of such drug, with intent that 
 the same may be sold in that state ; and no person shall sell any 
 drug so mixed, coloured, stained, or powdered . . ." (sec. 4). The 
 penalty for such injurious admixture is a fine not exceeding £50 
 for a first offence ; subsequent offences are misdemeanours, punish- 
 able by imprisonment with hard labour for a period not exceeding 
 six months. No liability is, however, incurred if the accused 
 person can show that he was unaware of the admixture, and could 
 not, with reasonable diligence, have ascertained it (sec. 5). 
 
 No person shall sell, to the prejudice of the purchaser, any 
 article of food or any drug which is not of the nature, substance, 
 and quality of the article demanded by such purchaser, under a 
 penalty not exceeding ^20 ; but no offence shall be deemed to be 
 committed under this section in the following cases : — (1) Where 
 any matter or ingredient not injurious to health has been added 
 to the food or drug because the same is required for the produc- 
 tion or preparation thereof as an article of commerce in a state 
 fit for carriage or consumption, and not fraudulently to increase 
 the bulk, weight, or measure of the food or drug, or conceal the 
 inferior quality thereof; (2) where the drug or food is a pro- 
 prietary medicine, or is the subject of a patent in force, and is 
 supplied in the state required by the specification of the patent ; 
 (3) where the food or drug is compounded . . . [and the pro- 
 
488 SANITARY LAW. 
 
 visions of the seventh and eighth sections are observed] ; (4) 
 where the food or drug is unavoidably mixed with some extrane- 
 ous matter in the process of collection or preparation " (sec. 6). 
 As regards these exemptions, the onus probandi rests with the 
 defendant (sec. 24). No person shall sell any compound, drug, 
 or article of food which is not composed of ingredients in accord- 
 ance with the demand of the purchaser, under a penalty not 
 exceeding ^£20 (sec. 7) ; but no offence under this section is 
 committed in respect of the sale of a drug or article of food mixed 
 with an ingredient not injurious to health, if it is labelled as 
 " mixed " at the time of sale (sec. 8). 
 
 " No person shall (with the intent that the same may be sold 
 in its altered state without notice) abstract from an article of food 
 any part of it, so as to affect injuriously its quality, substance, or 
 nature ; and no person shall sell any article so altered without 
 making disclosure of the alteration, under a penalty not exceeding 
 ^"20" (sec. 9). In any prosecution under this Act, the. defendant 
 is to be discharged if he proves to the satisfaction of the Court (a) 
 that he bought the article as being the same in nature, substance, 
 and quality with that demanded by the purchaser, and with a 
 written warranty to that effect ; (b) that at the time of sale he had 
 no reason to believe it to be otherwise ; and (c) that he sold it in 
 the same state as when he purchased it (sec. 25). 
 
 As an outcome of the report of a committee which inquired 
 into the uses and abuses of preservatives and colouring matters 
 in food, it is probable that this Act will be soon amended and 
 strengthened in special reference to these points ; the recommen- 
 dations made have already been given on p. 169. 
 
 In order to carry out the provisions of this Act, in every 
 district a competent person may be, and if required by the M.H. 
 must be, appointed as public analyst (sec. 10). In the case of 
 boroughs having a separate Court of Quarter Sessions, or a sepa- 
 rate police force, this appointment is made by the town council ; 
 while for all other parts of the country it is made by the county 
 council. All these appointments and re-appointments are subject 
 to the approval of the M.H. When a public analyst is thus 
 appointed, any purchaser of an article of food or drug within the 
 district shall be entitled to have it analysed for a fee of 10s. 6d., 
 otherwise by another analyst, at such fee as he may require, and 
 in either case to have a certificate of the result (sec. 12). The 
 M.O.H., the sanitary inspector, or any other officer charged by 
 the S.A. with the execution of the Act, may procure samples of 
 food and drugs, and submit them to the public analyst (sec. 13). 
 The quantities of the samples purchased under sec. 13 should not 
 be less, in the case of milk, than r pint ; butter, f of a lb. ; lard, 
 
ADULTERATION OF FOOD. 4^9 
 
 -J of a lb. ; coffee, | ot a lb. ; spirits, £ of a pint. Any person 
 purchasing an article for analysis shall, upon the completion of 
 the purchase, forthwith notify to the seller his intention to have it 
 analyzed by the public analyst ; and shall offer to divide it into 
 three parts, to be then and there separated, and each part to be 
 marked and sealed or fastened up, and shall, if required to do so, 
 proceed accordingly, and shall deliver one of the parts to the 
 seller. He must retain one of the three parts for future com- 
 parison, and deliver the third to the public analyst. 
 
 Samples may be sent to the analyst by post, in a registered 
 letter, if his residence is two miles from that of the purchaser 
 (sec. 1 6). Any person refusing to sell to an officer of the S. A. 
 any article of food or drug on sale by retail, the price being 
 tendered, and the quantity demanded not being greater than is 
 reasonably requisite, is liable to a penalty not exceeding ^10 
 (sec. 17). The certificate of the analyst must be in a prescribed 
 form (sec. 18), and is sufficient evidence of the facts therein 
 stated, unless the defendant requires the analyst to be called 
 as a witness (sec. 21). The B.A. have the power to fix the 
 limits of deficiency from the normal in the composition of milk, 
 cream, butter, etc. The justices before whom a case is heard 
 may, at the request of either party, cause any article of food or 
 drug to be sent to the Commissioners of Inland Revenue for 
 analysis by the chemists of their department at Somerset House 
 (sec. 22). 
 
 Owing to certain defects in the Act of 1875, an Amendment 
 Act was passed in 1879. This latter Act qualifies the earlier one 
 by stating that " it shall be no defence to allege that the purchaser 
 is not prejudiced by the sale of adulterated articles, on the ground 
 that he bought it for analysis only ; or to allege that the article in 
 question, though defective in nature, or substance, or quality, was 
 not defective in all three respects " (sec. 2). " The M.O.H., 
 inspector, or constable charged with the execution of the Act, 
 may procure, at ths place of delivery, a sample of milk in course 
 of delivery to the purchaser or consignee, in pursuance of any 
 contract ; and may submit the sample to the public analyst " 
 (sec. 3). " The seller, or his representative, if he refuses to allow 
 a sufficient sample to be taken, is liable to a penalty not exceed- 
 ing ;£io" (sec. 4). "As regards spirits not adulterated otherwise 
 than by admixture of water, it is a good defence to prove that the 
 admixture has not reduced the spirit more than 2$ degrees under 
 proof for brandy, whisky, or rum ; or 35 degrees under proof for 
 gin " (sec. 6). 
 
 Under the Milk and Dairies Acts, 19 15 and 1920, the pro- 
 ceedings as to taking of milk samples is somewhat different to 
 
490 SANITARY LAW. 
 
 that given for other foods and drugs in the S.F.D.A., 1875, '^99, 
 and 1907. The special provisions under the new Milk Act are 
 briefly as follows. A purveyor of milk from whom a sample has 
 been procured may be compelled to give name and address of the 
 consignor from whom he received the milk; and the S.A. may 
 take one or more samples in course of transit or delivery from 
 such consignor. Within sixty hours after the sample of milk was 
 procured from the purveyor, he may serve on the S.A. a notice 
 stating the name and address of the consignor from whom he 
 received the milk, and the time and place of delivery to the 
 purveyor by the seller or consignor of milk from a corresponding 
 milking, and requesting them to take immediate steps to procure, 
 as soon as practicable, a sample of milk in the course of transit or 
 delivery from the consignor, unless a sample has been so taken 
 since the sample was procured from the purveyor, or within 
 twenty-four hours prior to the sample being procured from the 
 purveyor ; and where a purveyor has not served such notice as 
 aforesaid, he shall not be entitled to plead a warranty as a defence 
 in any such proceedings ; and if the S.A., after such notice, fails 
 to procure a sample in accordance with the foregoing provisions 
 no proceedings may be taken under the S.F.D. Acts in respect of 
 the sample of milk procured of the purveyor. If proceedings are 
 taken against the purveyor, a copy of the analyst's certificate of 
 every sample taken in course of transit or delivery shall be 
 furnished to him. The S.A. may take proceedings not only 
 against the purveyor, but also against the consignor of milk. If 
 a sample is taken in course of transit or delivery, the owner of 
 the cows may, within sixty hours, serve on the S.A. a notice to 
 take immediate steps to procure, as soon as practicable, a sample 
 from a corresponding milking of the cows, and the foregoing 
 provisions shall apply accordingly. 
 
 In order to prevent the fraudulent sale of margarine for butter, 
 the Margarine Act, 1887, was passed. Sec. 3 of this Act defines 
 "butter" as made exclusively from milk, or cream, or both, with 
 or without salt or other preservative, and with or without added 
 colouring matter. " Margarine " includes all substances, whether 
 compounds or otherwise, prepared in imitation of butter, and 
 whether mixed with butter or not It shall be unlawful to manu- 
 facture, sell, or expose for sale, or import any margarine the fat 
 of which contains more than 10 per cent, of butter fat (S.F.D. A., 
 1899, sec. 8). Every package or parcel of margarine must be so 
 marked, in capital letters not less than three-quarters of an inch 
 square (sec. 6). All margarine factories must be registered with 
 the S.A., by whom the public analyst of the district is appointed 
 (sec. 9). Officers authorized to take samples under the Sale of 
 
ADULTERATION OF FOOD. 49 1 
 
 Food and Drugs Act may take samples of butter (or substances 
 purporting to be butter which are exposed for sale and not marked 
 as margarine) without going through the form of purchase required 
 by that Act, but otherwise complying with its provisions as to 
 dealing with the samples (sec. 10). Any such substance not being 
 marked as margarine is to be presumed to be exposed for sale as 
 butter, so that there is a possible offence under both Acts. There 
 is a saving clause similar to sec. 25 of the Sale of Food and 
 Drugs Act, viz. that the vendor is absolved if he proves that he 
 bought the article with a written warranty, and sold it, in the same 
 state as when bought, believing it to be butter. 
 
 Under the S.F.D.A., 1899, any person who imports into the 
 United Kingdom, any margarine or margarine-cheese, except in 
 packages conspicuously marked ; or adulterated or impoverished 
 butter (other than margarine) ; or adulterated or impoverished 
 milk or cream, except in packages or cans marked with a name or 
 description indicating that the butter or milk or cream has been 
 so treated ; or condensed, separated, or skimmed milk, except in 
 tins or other receptacles which bear a label whereon the words 
 " Machine-skimmed Milk " or " Skimmed Milk," as the case may 
 require, are printed in large and legible type ; or any adulterated 
 or impoverished food to which by Order in Council this section 
 shall be applied, shall be liable, on summary conviction, for the 
 first offence to a fine not exceeding £20, for the second offence 
 to a fine not exceeding ^50, and for any subsequent offence to a 
 fine not exceeding ^100. 
 
 The word "importer" in this Act includes any person who, 
 whether as owner, consignor, or consignee, agent, or broker is in 
 possession of, or in any wise entitled to the custody or control of 
 the article. Prosecutions for offences under these sections of the 
 Act shall be undertaken by the Commissioners of Customs, who 
 shall take such samples as necessary ; divide each sample into 
 three parts, sending one to the importer, one to the principal 
 chemist of the Government laboratories, and retaining one part 
 (sees. 1 to 4). The result of the analysis in the certificate of the 
 principal chemist shall be sufficient evidence of the facts therein 
 stated. If an offence has been committed, the name of the 
 importer and the destination of the consignment shall be com- 
 municated to the Board of x\griculture by the Customs. An 
 article of food shall be deemed to be adulterated or impoverished 
 if it has been mixed with any other substance, or any part 
 abstracted so as to affect injuriously its quality, substance, or 
 nature. 
 
 When either the M.H. or the B. of A. consider, in relation to 
 any articles of food, that the general interests of the consumers and 
 
4Q2 SANITARY LAW. 
 
 agriculture respectively have been or are affected adversely they 
 may direct one of their officers to procure for analysis samples of 
 food as if he were an officer authorized to act under the S.F.D.A., 
 1875, except that the sample shall be divided into four parts, 
 three of such parts being dealt with as under sec. 14 of the 
 S.F.D.A., 1875, as amended by this Act of 1899, an d the fourth 
 part sent to the M.H. or B. of A. as the case may be. If any S. A. 
 fails to enforce or execute any of the provisions of the S.F.D.A. 
 in relation to any article of food, and such failure affects the 
 interests of the consumers or agriculture, either the M.H. or B. of 
 A., as the case may demand, may by Order empower one of their 
 officers to execute and enforce these provisions and charge any 
 expenses to the defaulting sanitary authority. 
 
 The B. of A. may make Regulations (sec. 4) as to the 
 deficiency of normal constituents, the addition of extraneous 
 matter and the proportion of water in respect of milk, cream, 
 butter, and cheese. The following Regulations have been made. 
 Sale of Milk Regulations, 1901, to the effect that milk not sold as 
 skimmed, separated, or condensed milk, shall be presumed to be 
 not genuine if it contains less than 3 per cent, of milk fat and less 
 than 8*5 per cent, of milk solids other than milk fat. Sale of 
 Milk Regulations, 191 2, to the effect that skimmed or separated 
 milk, not being condensed milk, shall be presumed to be not 
 genuine if it contains less than 87 per cent, of solids not fat. An 
 amendment Order of 191 7 to these Regulations forbids more than 
 28 grains of boric acid to be added to the pound of preserved 
 cream. No thickening substance may be added to cream, and no 
 preservatives may be added to cream containing less than 35 per 
 cent, by weight of fat. Only boric acid, borax, or peroxide of 
 hydrogen may be added to cream containing 35 per cent, or 
 more of fat. If so treated, such cream must be labelled as 
 "preserved cream." The Sale of Butter Regulations, 1902, state 
 that butter containing more than 16 per cent, of water shall be 
 presumed to be not genuine. 
 
 The Margarine Act, 1907, lays down that margarine must be 
 sold as such or by a name embracing the word " margarine." 
 Milk-blended butter must be sold under such name as may be 
 approved by the B. of A., and the wrapper must set out the 
 percentage of water contained therein and approved by the Board. 
 This Act gives powers also to B. of A., to M.H., and the S.A. 
 over all processes of manufacture, blending, reworking, or treat- 
 ment of butter and similar substances, and moreover lays down a 
 limit of not more than 16 per cent, of moisture in butter and 
 margarine, and not more than 24 per cent, in milk-blended 
 butter. Such goods may not be imported. Powers are also given 
 
INFECTIOUS DISEASES. 493 
 
 to M.H. as to prohibition of the use of preservatives in butter, 
 margarine, and milk- blended butter. 
 
 A prosecution under S.F.D.A., 1899, in respect to the sale of 
 adulterated food, must be instituted within twenty-eight days, and 
 a warranty or invoice is no defence unless defendant, within seven 
 days after service of summons, sends to purchaser a copy of such 
 warranty or invoice, and a written notice that he intends to rely 
 on that warranty (sees. 19 and 20). 
 
 Infectious Diseases. — The P.H.A., 1875, enacts that, upon 
 the certificate of a M.O.H. or other medical practitioner that the 
 cleansing and disinfecting of any house or part thereof, and of 
 any articles therein, would tend to prevent infectious disease, it is 
 incumbent on the S.A. to serve notice upon either the owner or 
 occupier, requiring him to cleanse and disinfect. A daily penalty 
 not exceeding 10s. is incurred by default, and the authority may 
 do what is necessary and recover the costs, or may undertake the 
 duty in the first instance, with the consent of the occupier, at 
 their own cost (sec. 120). Under the I.D.P.A., 1890 and 1899, 
 the above section is repealed, and the provisions so far modified 
 that the S.A. may, after twenty-four hours' notice, proceed to carry 
 out such disinfection or cleansing, unless within that time the 
 owner or occupier informs the authority that he will, within a 
 period fixed in the notice, himself carry out the work to the satis- 
 faction of the M.O.H. In case of default, the S.A. may cause the 
 necessary work to be done and recover the expenses. Power of 
 entry between 10 a.m. and 6 p.m. is given for the purposes of 
 this section (Infectious Diseases Prevention Act, 1890, sees. 5 
 and 17). 
 
 By sec. 121, P.H.A, 1875, tne S.A. may destroy infected 
 bedding, clothing, or other articles, and give compensation. By 
 sec. 6 of the Act of 1890, the authority may, by a written notice, 
 require, under a penalty of ^10, any infected clothing or other 
 articles to be delivered to their officers for disinfection. The S.A. 
 must take away, disinfect, and return such articles free of charge, 
 and, in the event of any unnecessary damage, must compensate 
 the owner. 
 
 The P.H.A., 1875, further enacts that a S.A. may provide a 
 disinfecting apparatus and disinfect free of charge (sec. 122); 
 also provide an ambulance and pay expenses of conveyance to 
 hospital of infected persons (sec. 123). Where a hospital is 
 provided within convenient distance, a justice may, on the 
 certificate of a medical practitioner, order the removal of any 
 person who is suffering from any dangerous infectious disorder, 
 and is without proper lodging or accommodation, or is lodged in 
 a room occupied by more than one family, or is on board any ship 
 
494 SANITARY LAW. 
 
 or vessel (sec. 124). The authority may make regulations for 
 removing to any available hospital, and for keeping there as long 
 as necessary, any persons brought within their district by vessel, 
 who are infected with a dangerous infectious disorder (sec. 125). 
 It is unlawful for any person so suffering to expose himself 
 wilfully, without proper precautions against spreading the dis- 
 order, in any street, public place, shop, inn, or public conveyance, 
 or to enter any public conveyance without previously notifying to 
 the owner, conductor, or driver thereof that he is so suffering ; or, 
 being in charge of any person so suffering to expose such sufferer, 
 or to give, lend, sell, transmit, or expose without previous dis- 
 infection any bedding, clothing, rags, or other things which have 
 been exposed to infection from any such disorder, but this does 
 not apply to the transmission with proper precautions of articles 
 for the purpose of having them disinfected (sec. 126). The 
 owner or driver of a public conveyance so used is required under 
 penalty to have the same immediately disinfected, but he need 
 not convey any person so suffering until he has been paid a sum 
 sufficient to cover any loss or expense incurred by him (sec. 127). 
 Any person who knowingly lets for hire any house or room in 
 which any person has suffered from such disorder, without having 
 it and its contents disinfected to the satisfaction of a medical 
 practitioner, as testified by a certificate signed by him, is liable to 
 a penalty not exceeding ^20 (sec. 128). Any person letting or 
 offering for hire any house or part of a house, who on being 
 questioned as to the fact of there being, or within six weeks 
 previously having been therein, any person suffering from any 
 dangerous infectious disorder, knowingly makes a false answer 
 to such question, becomes liable to penalty or imprisonment 
 (sec. 129). 
 
 The above provisions have been supplemented in districts 
 by the I.D.P.A., 1890, by the following enactment in sec. 7 
 of that Act. It provides that any person who shall cease to 
 occupy any house or room in which any person has, within six 
 weeks, been suffering from any infectious disorder, (1) must have 
 such house or room, and all articles therein liable to retain 
 infection, disinfected to the satisfaction of a registered medical 
 practitioner, as testified by a certificate signed by him ; and (2) 
 must give to the owner notice of the previous existence of such 
 disease ; and (3) must not knowingly make a false answer when 
 questioned by the owner, or by any person negotiating for the 
 hire of the house or room, as to there having, within six weeks 
 previously, been therein any person suffering from any infectious 
 disease. Penalties of ^10 are provided in each case. Infectious 
 rubbish must not be thrown into any receptacle for refuse without 
 
INFECTIOUS DISEASES. 495 
 
 previous disinfection j or in default a daily penalty ot 40.$-. 
 (sec. 13). In any district where these sections are in force, the 
 S.A. must give notice of their provisions to the occupier of any 
 house in which they are aware there is a person suffering from 
 any infectious disease (sec. 14). 
 
 The P.H.A., 1875, sees. 131 to 133, enacts that any S.A. 
 may build or contract for the use of hospitals for their district, 
 two or more authorities, if necessary, combining for this purpose. 
 The S.A. may recover from a patient, who is not a pauper, the 
 cost of his maintenance in such hospital ; and may, with the 
 sanction of the M.H., themselves provide or contract for a 
 temporary supply of medicine and medical assistance for the 
 poor of their district. Further, the I.D.P.A., 1890, requires the 
 same authorities to provide free temporary shelter with any 
 necessary attendance, for the members of any family in which 
 infectious disease has appeared, who have to leave their dwellings 
 to allow of disinfection by the S.A. Any person suffering from 
 infectious disease, and being an inmate of a hospital for infectious 
 diseases, and who upon leaving would be without accommodation 
 in which due precautions could be taken against the spread of 
 infection, may, by order of a justice, be detained in hospital at 
 the cost of the S.A. for any specified period, and such period may 
 be extended as often as necessary (sec. 12, Act of 1890). 
 
 With a view to promote the establishment of infectious 
 hospitals, a very important Act was passed in 1893, called the 
 Isolation Hospitals Act, giving to county councils limited power 
 to secure the provision of isolation hospitals in their county. It 
 applies to England and Wales generally, but not to London, or to 
 any county borough • other boroughs are also exempt, except by 
 order of the M.H., if the population be less than 10,000, at the 
 last census, or by consent of the corporation if the population be 
 10,000 or more. A hospital district under this Act may consist 
 of one or more local areas ; a " local area " being defined as 
 including an urban or rural sanitary district, or any contributory 
 place. This district is constituted by order of the county council. 
 To put this Act in force, the county council may take the 
 initiative by directing their M.O.H. to report as to the hospital 
 requirements of any part of their county, and acting upon his 
 report ; but they may also be set in motion by a petition from 
 any local authority, or from twenty-five ratepayers in any con- 
 tributory place. The next step is for the county council to hold 
 a local inquiry, after which they make an Order constituting the 
 hospital district and defining its extent. No local area can be 
 included in a hospital district without the consent of its local 
 authority, if it has already, in the judgment of the county council, 
 
496 SANITARY LAW. 
 
 adequate accommodation ; nor must a hospital district be formed 
 for one local area only, or for one or more local areas within the 
 same rural sanitary district, without the consent of the S. A., unless 
 the county council are satisfied that the S.A. are unable or 
 unwilling to make suitable provision for the purpose. The Order 
 constitutes a hospital committee, consisting of local representa- 
 tives, but if a grant be made out of county funds, the committee 
 may consist wholly or in part of county councillors. The Order 
 further gives the committee power to provide and maintain a 
 hospital ; and apart from this they are authorized by this Act 
 to make temporary arrangements for isolation, and to establish 
 district hospitals in cottages or small buildings. They may also, 
 subject to county council regulations, undertake the training of 
 nurses, and may charge for their attendance outside the hospital. 
 Every hospital is to be provided with one or more ambulances, 
 and must, if practicable, be in connection with the system of 
 telegraphs (sec. 13). 
 
 The county council have the power of 'inspecting any such 
 hospital, and of raising money by loan for the purposes of the 
 hospital. 
 
 "Structural" and "establishment" expenses are borne by the 
 several local rates of the constituent local areas, in proportions to 
 be fixed by the county council's Order. The cost of conveying, 
 removing, feeding, medicines, disinfecting, and all other things 
 required for patients individually, are termed " patients' expenses." 
 For ordinary non-pauper patients they are to be paid by the local 
 authority out of the rates of the local area from which the patient 
 came, but the guardians are responsible if poor-law relief has been 
 given at or within fourteen days at the time of admission. Patients 
 desiring exceptional accommodation are themselves responsible 
 for the cost of maintenance, " special patients' expenses," on such 
 terms as the committee may appoint (sees. 17 to 19). 
 
 The I.H.A., 1893, has been considerably amended by the 
 I.H.A. of 1 901. Hitherto there has been some doubt as to the 
 extent of the power of a district council or joint board who 
 had provided a hospital under the P.H.A., 1875, to transfer their 
 hospital to the county council. These powers have now been 
 clearly explained, and facilities for exercising them materially 
 furnished by the later Act. Further, difficulties in the way of 
 hospital committees hiring temporarily a hospital from a district 
 council whilst they themselves were erecting a permanent hospital, 
 and also as to transferring patients from one district to the hospital 
 of other authorities in times of stress or epidemics, are removed. 
 The new Act, sec. 5, also provides that upon an appeal against 
 any Order including any area in a hospital district under subsec. 3 
 
infectious Diseases. 497 
 
 of sec. 8 of the Act of 1893, the M.H. may confirm, disallow, 
 or modify the Order as they think fit. Sec. 6 of the new Act 
 now provides that the rural district council shall, to the exclusion 
 of any other authority, be the local authority in the case where a 
 contributory place consisting of a parish is concerned. Hitherto, 
 under the Act of 1893, a county council could only be represented 
 upon a hospital committee by members of- their own body. This 
 is altered by sec. 8 of the new Act, whereby the representatives of 
 the county council upon a hospital committee may be members 
 of the council or not. 
 
 It is, of course, of the greatest importance from a sanitary point 
 of view that the dead bodies of persons who have died of infectious 
 diseases should not remain unburied in such a manner as to 
 endanger the health of the survivors. The P.H.A., 1875, sec. 
 142, provides that where the dead body of any one who has died 
 of any infectious disease is retained in a room in which persons 
 live and sleep, any justice may, on a certificate signed by a 
 medical man, order the body to be' removed by the S.A. to a 
 mortuary, and direct the same to be buried within a time to be 
 limited by the Order ; unless the friends of the deceased undertake 
 to so bury the body within the time specified, it is the duty of 
 the relieving officer to bury such body at the expense of the poor- 
 rate ; but any expenses so incurred may be recovered in a 
 summary manner from any person legally liable to pay the 
 expenses of the burial. A penalty of ^5 attaches to any person 
 obstructing the execution of an order made under this section 
 
 Further provisions in respect of this matter are contained 
 in sees. 8 to 11 of the Act, the I.D.P.A., 1890, which enact 
 that the body of a person who has died of any infectious disease 
 must not, without a certificate from the M.O.H. or a registered 
 medical practitioner, be retained for more than forty-eight hours 
 elsewhere than in a mortuary, or «in a room not used at the 
 time as a dwelling-place, sleeping- place, or workroom. In such 
 cases, and also where any corpse is retained in a building so as 
 to endanger the health of the inmates, a justice may, upon the 
 application of the M.O.H., order the body to be removed by the 
 S.A. to a mortuary, and to be buried within a specified time. 
 Unless the friends undertake to bury, and do bury within the 
 specified time, the relieving officer must do so. The body of any 
 person who has died from infectious disease in a hospital must 
 not be removed except for immediate interment or to a mortuary, 
 if the M.O.H. or other medical practitioner certify that such 
 restriction is desirable for preventing infection. The body of any 
 person who has died of an infectious disease must not be con- 
 veyed in any public conveyance, other than a hearse, without due 
 
498 SANITARY LAW. 
 
 warning to the owner or driver, who must forthwith provide for 
 disinfection. 
 
 In cases where there is any suspicion that an epidemic of 
 infectious disease has its origin in any milk supply of the district, 
 the powers of a S.A. under the CD. (Animals) A., 1886, as 
 amplified and amended under the Milk and Dairies Acts, 191 5 and 
 1920, should not be lost sight of. They have been fully 
 explained in the preceding section. In addition to these powers 
 and provisions, sanitary authorities of districts have power to 
 prohibit the supply of milk from suspected dairies (sec. 4, 1.D.P.A., 
 1890). If the M.O.H. has reason to believe that the con- 
 sumption of milk from any dairy, farm, cowshed, milk-store, 
 milk-shop, or other place from which milk is supplied within 
 or without his district, has caused or is likely to cause infectious 
 disease to any person residing in the district, he may, if authorized 
 by a justice having jurisdiction in the place where the dairy is 
 situate, inspect the dairy. He may further, if accompanied by 
 a veterinary surgeon, inspect the animals therein. If after 
 inspection he is of opinion that infectious disease is caused by 
 the consumption of the milk, he must report to the S.A., forward- 
 ing also any report furnished to him by the veterinary surgeon. 
 The local authority may then give not less than twenty-four hours' 
 notice to the dairyman to appear before them, and show cause 
 why the supply of the milk in their district should not be pro- 
 hibited. If in their opinion he fails to show such cause, they 
 may order accordingly, and must give notice of the facts to the 
 S.A. and the county council of the district in which the dairy is 
 situate, and also to the M.H. The order must be forthwith 
 withdrawn on the S.A. or the M.O.H. being satisfied that the 
 milk supply has been changed, or that the cause for infection has 
 been removed. Penalties of ^5, and if a continuing offence 
 of 40s. a day, are provided* for contravention of this section of 
 the Act. 
 
 In respect of tuberculosis, considerable control and means of 
 taking action against this disease arise out of the National In- 
 surance Act, 191 1. Although this is a public health Act, in actual 
 practice a S.A. and its officers have comparatively little to do with 
 its administration. The working of its provisions is centralized 
 in the M.H., which operates mainly through Insurance Com- 
 mittees where such have been established. In many areas, these 
 Insurance Committees exist distinct from the S.A. This latter 
 body, therefore, concerns itself chiefly with those sections of the 
 Act making special reference to the S.A. Sections 16 and 22 of 
 the N.I. A., 191 1, deal with tuberculosis and sanatorium benefits 
 and empower councils of boroughs and districts to contribute 
 
INFECTIOUS DISEASES. 499 
 
 :ertain expenditure on medical and sanatorium benefit. Sec. 17 
 *ives power to extend sanatorium benefit to dependants. The 
 nost important provisions of the Act are in sees. 59 to 62 in- 
 ;lusive, which give power to Insurance Committees to provide 
 ;uberculosis dispensaries, sanatoria, and hospitals for advanced 
 :ases of tuberculosis. The practice in relation to Insurance 
 Committees varies. Where such exist they can act independently 
 )f the S.A., but in a number of places the local S.A. is the 
 [nsurance Committee, an arrangement which is convenient and 
 vorks well. Sec. 63 authorizes inquiries to be held in districts in 
 vhich excessive sickness occurs, due or alleged to be due to 
 leglect on the part of the S.A. 
 
 The control of venereal disease is furnished by the P.H. 
 Venereal Diseases) Regulation, 191 6, and the Venereal Disease 
 \ct, 191 7. Venereal disease means syphilis, gonorrhoea, and soft 
 mancre. By the Regulations, 19 16, every County Council and 
 County Borough Council in England and Wales and the Common 
 Council of the City of London must prepare and submit to the 
 VI. H. a scheme, (a) for the treatment at and in hospitals or other 
 nstitutions of persons suffering from venereal disease ; and (b) for 
 applying medical practitioners with salvarsan or its substitutes 
 or the treatment and prevention of venereal disease. After 
 Lpproval by the M.H., the council concerned must put the scheme 
 nto execution at its own cost. All information obtained in 
 egard to any person treated under the scheme approved shall be 
 egarded as confidential. With the approval of the M.H. any 
 :ouncil may make arrangements to delegate its powers to the 
 nanagers of a hospital, institution, or society. Any council may 
 nake provisions for the giving of instructional lectures or publica- 
 ion of information relating to venereal disease. Under the V.D.A., 
 [917, no one but a duly qualified medical practitioner may, for 
 eward either direct or indirect, treat, prescribe for, or advise any 
 )erson for venereal disease. This applies only to areas where a 
 jratuitous' scheme approved by the M.H. is in operation. No 
 )erson, other than a S.A. or M.H., is allowed to treat any person 
 vith venereal disease, or advise treatment by advertisement or 
 Dublic notice, nor may he recommend any internal or external 
 nedicines or medicaments for the cure, relief, or prevention of 
 venereal diseases. The penalties under this Act are severe 
 igainst offenders, being imprisonment with hard labour up to two 
 rears, or a fine up to ^100. 
 
 The relation of schools/to infectious diseases, and the action 
 )f the S.A. in the matter, is of importance. By Article 88 of the 
 Education Code, a S.A. has alternative power with respect to 
 elementary public schools : (a) to notify the managers that par- 
 
500 SANITARY LAW. 
 
 ticular scholars be for a specified time excluded from attendance, 
 or (if) to require the school to be closed for a specified time. 
 Managers of schools, after complying with the requirements of a 
 S.A., have the right of appeal to the Education Department, if 
 they consider any notice to be unreasonable. A S.A. has no 
 power in respect to Sunday schools, or other private schools; 
 except in so far as these may contravene sect. 91 (5) (nuisance 
 from overcrowding), or sec. 126 (exposure of infected person 
 or thing), or other provision of the P.H.A., 1875, Dut usually the 
 managers of such schools are only too ready to co-operate in 
 efforts for securing the public health. 
 
 Where the Public Health Acts Amendment Act, 1907, is 
 adopted, the powers of the S.A. to deal with the infective 
 diseases are materially strengthened. By sec. 52 of this Act, 
 if any person knows that he is suffering from an infectious disease 
 he shall not carry on any trade or occupation unless he can do 
 so without risk of spreading the infectious disease. The penalty 
 in respect of each offence is forty shillings. Further, if the 
 M.O.H. suspects that any case of infectious disease is attributable 
 to the milk-supply, the S.A. can call upon the dairyman supplying 
 the milk to furnish a list of places from which he derives such 
 supply. Payment for these lists to be at the rate of sixpence 
 for every twenty-five names. Failure to comply entails a fine 
 of £$ and a running penalty not exceeding £2 per day (sec. 53). 
 Dairymen are also required to notify the medical officer of any 
 cases of infectious disease amongst their employees (sec. 54). 
 
 Infected clothes may not be sent to a laundry, and the S.A. 
 may, on application of any person, pay the expenses of the 
 disinfection of any such clothing or bedding, if carried out by 
 them or under their direction (sec. 55). Also, the authority 
 is empowered to cleanse, purify or destroy any article in a 
 dwelling-house which, by reason of its filthy condition, might 
 prove dangerous to the health of any persons in the house. 
 Reasonable compensation to owner may be given (sec. 56). 
 
 Children suffering from infectious disease may not attend 
 school (sec. 57), and principals of schools where a scholar is 
 suffering from an infectious disease can be called upon to furnish 
 lists of scholars to the S.A. ; the penalty in default being a fine of 
 40s. These lists to be paid for at the rate of sixpence for 
 twenty-five names (sec. 58). The borrowing of books from 
 public or circulating libraries is illegal for persons knowing 
 themselves to be suffering from an infectious disease (sec. 59). 
 
 Further material powers of control over infectious diseases 
 arise out of the provisions of the Midwives Acts, 1902 and 1918, 
 as to the extension of diseases of this kind among lying-in women. 
 
INFECTIOUS DISEASES. 5<DI 
 
 by the Cleansing of Persons Act, 1897, and the Children Act, 
 1908, especially as to the cleansing of verminous children. 
 
 Under sec. 61 of P.H. (Amend.) Act of 1907, a S.A. may 
 exercise powers of sec. 15 of the Infectious Disease (Prevention) 
 Act, 1890, whether that section has or has not been adopted in 
 the district, and, if they so determine, can remove persons from 
 infected premises and provide for their temporary shelter or 
 accommodation. If any such person does not consent to be so 
 removed, a compulsory order from two justices can be obtained 
 on application by the S.A. Penalties attach to wilful disobedience 
 or obstruction of an order under this section. Sec. 126 of the 
 P.H.A., 1875, which imposes a penalty on the exposure of 
 infected persons and things is amended so as to read in paragraph 
 two as if the words " or causes or permits such sufferer to be 
 exposed" followed after the word "sufferer" (sec. 62). Owners 
 or drivers of public vehicles are prohibited from knowingly 
 conveying infected persons in public vehicles, but if such 
 incident come to their knowledge they must give notice to the 
 S.A., who must, on request of the owner or driver of such 
 public vehicle, disinfect the same free of charge, except in cases 
 where the owner or driver knew that the person conveyed was 
 suffering from infectious disease (sees. 63 and 64). Full powers 
 to cleanse and disinfect premises are given to the S.A. on 
 certification by their medical officer that such cleansing and 
 disinfection is necessary to prevent or check disease. Notice to 
 do so may be given to owner or occupier, failure to comply 
 within twenty-four hours gives the S.A. power to enter on any 
 premises by day and carry the disinfection out under the super- 
 intendence of the medical officer. Reasonable compensation 
 for damage must be given (sec. 66). A S.A. may provide 
 nursing attendance for cases of infectious disease, where removal 
 to hospital is likely to endanger the patient's health (sec. 67). 
 The holding of wakes over bodies of persons dying of infectious 
 diseases is unlawful (sec. 68). 
 
 One of the most important and valuable aids to the various 
 foregoing provisions has been the co?npulsory notification of in- 
 fectious diseases under the Notification Acts of 1889 and 1899, 
 coupled with extensions of scheduled diseases under various 
 Public Health Regulations issued since. The diseases now 
 scheduled as compulsorily notifiable are : small-pox, cholera, 
 diphtheria, membranous croup, erysipelas, scarlet fever, typhus 
 fever, enteric fever, continued fever, relapsing fever, puerperal 
 fever, plague, tuberculosis in all forms, cerebro-spinal fever, acute 
 poliomyelitis, ophthalmia neonatorum, measles and German 
 measles, acute encephalitis lethargica, acute polio-encephalitis, 
 
502 SANITARY LAW. 
 
 acute primary pneumonia, malaria, dysentery, and trench fever. 
 Power is given to a S.A., with the sanction of the M.H., to adopt 
 within its district the notification of any other infectious disease; 
 this is occasionally done in respect of whooping cough and 
 chicken-pox, especially during times of epidemicity. Every 
 medical practitioner attending on, or called in to visit, the patient 
 shall forthwith, on becoming aware that the patient is suffering 
 from an infectious disease to which this Act applies, send to the 
 medical officer of health for the district a certificate stating the 
 name of the patient, the situation of the building, and the infectious 
 disease from which, in the opinion of such medical practitioner, 
 the patient is suffering. The penalty for default is a fine not 
 exceeding 405-. Under the same penalty, the householder is 
 compelled to notify, but in a less formal manner. Though the 
 system of notification is " dual " under the Act, it is so only in 
 theory ; as practically the householder's share in the notification 
 is allowed to lapse, unless there is no doctor in attendance. The 
 Act does not apply to Government buildings, such as barracks, 
 nor to any " hospital " in which persons suffering from infectious 
 disease are received ; it applies to " every ship, vessel, boat, tent, 
 van, shed, or similar structure used for human habitation." The 
 Act gives no power of compulsory removal of patients to hospital, 
 nor even power of entry upon premises for the purpose of making 
 inquiries. 
 
 Sec. 130, P.H.A., 1875, enables the M.H. to make regu- 
 lations for the treatment of persons affected with cholera or 
 any other infectious disease, and by the P.H. Acts, 1896 and 
 1904, to make regulations for preventing the spread of such 
 diseases as well on the seas, rivers, and waters of the United 
 Kingdom, and on the high seas within 3 miles of the coast 
 thereof, as on land, and may declare by what S.A. such regulations 
 shall be enforced and executed. Cholera, plague, and yellow fever 
 regulations have been issued under these Acts. 
 
 The main principles on which regulations on this matter have 
 proceeded are that a report with regard to infected vessels 
 arriving from foreign ports should be made by the Officers of 
 Customs to the Port S.A. of the place on arrival ; that infected 
 vessels should be detained temporarily, pending visitation by 
 the M.O.H. of the place ; and that, after visitation by the M.O.H. 
 of such vessels, or of any other vessels to which suspicion of 
 infection attaches, the measures indicated by the regulations 
 should be taken. Such measures have included, according to 
 circumstances, the further detention of the vessel, the removal 
 of persons suffering or suspected to be suffering from plague, 
 cholera, or yellow fever, the adoption of steps to free the vessel 
 
INFECTIOUS DISEASES. 503 
 
 from causes of infection, and such other action as is expedient for 
 the purposes of tracing the further movements of persons allowed 
 to leave the vessel. Some modifications of the regulations have 
 now been made. 
 
 In relation to vessels arriving from foreign ports, a new 
 classification is adopted. The term " infected ship " is limited 
 to a ship on which there is actually on board at the time a case of 
 cholera, yellow fever, or plague, or on which there has been a case 
 of cholera or plague within seven days before arrival, or a case of 
 yellow fever within eighteen days before arrival. At the same 
 time the term " suspected ship " is used as applying to a ship 
 on which there has been a case of cholera or plague more than 
 seven days before the arrival of the ship, or a case of yellow 
 fever more than eighteen days before arrival, whether the case 
 has occurred in the port of departure or in another port in the 
 course of the voyage, or at any time during the voyage, and on 
 which no fresh case of cholera or plague has occurred within the 
 seven days, or of yellow fever within the eighteen days. In this 
 connection, it is important that the M.O.H. of a port should keep 
 themselves informed as to the ports that may be infected, and 
 should advise the local Officers of Customs as to the ports from 
 which it is anticipated that ships liable to detention by those 
 officers might come, or at which they might have called. 
 
 If a ship is certified to be " infected " the regulations 
 (except as regards any person actually suffering from cholera, 
 yellow fever, or plague, or from any illness which may prove to 
 be one or other of those diseases) prohibits the landing of any 
 person who is on board, unless he satisfies the M.O.H. as to his 
 name, intended destination, and intended address at such place. 
 As regards a "suspected" ship, a similar provision does not come 
 into operation unless the M.O.H. certifies that it is desirable that 
 the provision should take effect. In either case the permission 
 to land is coupled with an obligation that any change of address 
 or destination within five days after landing must be notified 
 forthwith either to the Port Medical Officer or to the S.A. of 
 the district in which the place of actual destination or address is 
 situate. 
 
 Under the regulations the measures of disinfection that may 
 be applied to an infected or a suspected ship, as apart from 
 articles in it, are restricted to instances in which the infection is 
 due to cholera or plague, and they are to be confined to those 
 parts of the ship which have been used as quarters by the person 
 so infected, or which, in the opinion of the M.O.H., are iniected 
 with either of these diseases. The disinfection or destruction of 
 articles on board the ship is restricted to those which may be 
 
§04 SANITARY LAW. 
 
 infected with cholera or plague. Similarly, certain proceedings 
 for dealing with bilge water, water ballast, drinking and cooking 
 water, which under former regulations were requisite in the case 
 of yellow fever and plague, are now made necessary only in those 
 instances where cholera is in question. 
 
 Provisions have been made for preventing the transmission 
 of plague by rats on board ship, and the escape from the ship to 
 the shore of rats that may be infected with plague. These are 
 obligatory in the case of infected ships, but in the case of a 
 suspected ship, only where the M.O.H. requires them to be 
 followed. Where a ship is neither infected nor suspected by 
 reason of plague, but has come from, or has during the voyage 
 called at, a port infected with plague, the M.O.H. by so 
 certifying that they are necessary, the measures for destruction 
 of rats are to be applied and the cost borne by the S.A. The 
 enforcement of measures for effectually stopping the access of 
 rats from the ship to the shore is left to the discretion of the 
 M.O.H. 
 
 In view of the part now known to be taken by a certain 
 species of mosquito in the transmission of yellow fever to man, 
 a provision is made enabling the M.O.H. to give a certificate 
 requiring the taking of measures intended to secure the destruc- 
 tion of mosquitoes and their larvae on board ship subject to 
 the conditions set out in that article. The S.A. are obliged to do 
 any such work as is specified at the request of and in substitution 
 for the master of the ship. If they think fit, they can recover the 
 cost of the work so done, but they may not derive any profit, and 
 the amount recoverable may not, in relation to any piece of work, 
 exceed ,£20. 
 
 For the Metropolis, the legislative enactments relating to 
 infectious diseases are practically all contained in the P.H. (Lond.) 
 A., 1891, sees. 55 to 87, as both the I.D.N.A., 1889 and 1899, 
 and the I.D.P.A., 1890, are embodied in the London Act of 189 1. 
 There are, however, a few modifications necessitated by the fact 
 that the whole of the Metropolis has been formed into one asylum 
 district, under managers known as the Metropolitan Asylums 
 Board, who, by the Metropolitan Poor Acts of 1867, 187 1, and 
 the Diseases Prevention (Metropolis) Act, 1883, provide asylums 
 for the insane and infirm as well as hospitals for infectious 
 diseases. 
 
 As regards notification in London, there is an important 
 difference of procedure as compared with England and Wales, 
 namely, that a copy of the certificate must be sent by the M.O.H. 
 of a sanitary authority both to the Asylums Board and to the head 
 teacher of the school attended by the patient (if a child), or by 
 
CANAL BOATS. 505 
 
 any child who is an inmate of the same house as the patient. 
 Besides this, the different medical officers of health receive weekly 
 a. full and complete list from the Asylums Board of all notifications 
 in the respective metropolitan districts. 
 
 The London County Council have power to extend the 
 provisions of the Act as to the notification of infectious disease 
 to diseases not specifically mentioned. The other general pro- 
 visions as to disinfection, removal of infected persons or dead 
 bodies, and burial of the infective dead, are similar to those 
 llready explained, 
 
 Power is a-lso given to the M.H, by sec. 13 of the 
 L.C.C. (G.P.) A., 1890, to assign to the county council any 
 duties and powers under epidemic regulations made by them in 
 pursuance of sec. 134, P.H.A., 1875, as tnev deem desirable. 
 In extension of the same, they may substitute the London 
 County Council for any local authority, on whose default the 
 council have power to proceed and act under the London 
 Public Health Act of 189 1. 
 
 Canal Boats. — Under the Canal Boats Acts of 1877 and 
 1884, the supervision of canal boats is placed under every S.A. 
 through whose district a canal takes its course, or which has a 
 piece of water coming under the definition of the word canal. It 
 is further the duty of the S.A. to report annually as to the 
 execution of the Acts, and as to any steps taken during the year 
 to give effect to them. In the following summary, the sections 
 quoted are those of the 1884 Act, unless expressly stated to be 
 otherwise. 
 
 No canal boat must be occupied as a dwelling unless it is 
 registered under these Acts, and then only by the number of 
 persons of the age and sex for which it is registered (sec. 1). 
 The owner can register the boat with any registration authority 
 having a district abutting on the canal on which such boat is 
 accustomed or intended to ply ; and the boat must be registered 
 as belonging to some place which is within the said district 
 (sec. 7). When the boat passes from the canal on which the 
 district of the authority with whom it has been registered abuts, 
 its original registry will be recognized as operative on other 
 canals whereon it may ply. If a canal boat is used in contra- 
 vention of the Acts, the master of the boat, and also the owner, 
 if he is in fault, will be each liable to a fine not exceeding 20s. 
 for each occasion on which the boat is so used. Directly a canal 
 boat ceases to be inhabited, it is no longer subject to the Canal 
 Boats Acts. Upon registration, two certificates must be given to 
 the owner, identifying the owner and the boat, and stating the 
 place to which it belongs, and the number, age, and sex of the 
 
506 SANITARY LAW. 
 
 persons allowed to dwell in the boat. The master of the boat 
 must carry one of these certificates (sec. 3). A boat cannot be 
 considered to be registered unless it is marked with (a) the name 
 of the place to which the boat belongs ; (b) the number ; (c) the 
 word " registered." Further, a boat will not be deemed to be 
 lettered, marked, and numbered in conformity with these require- 
 ments unless it is so lettered, marked, and numbered on both 
 sides of it, or in some suitable position plainly visible from both 
 sides of the boat (sec. 7). A certificate of registration will cease 
 to be in force in the event of any structural alterations having 
 been made in the canal boat affecting the conditions upon which 
 it was originally registered (sec. 1). 
 
 If any person on a canal boat is suffering from an infectious 
 disease, the S.A. of the place where the boat is shall adopt such 
 precautions as appear necessary, upon the certificate of the 
 M.O.H., or other legally qualified practitioner; and may remove 
 such sick person, and exercise the other powers conferred by 
 the P.H.A., 1875, m tms respect, and may detain the boat as 
 long as is necessary for cleansing and disinfecting (sec. 4, 
 Act of 1877). If any person duly authorized by the S.A. has 
 reason to suspect any contravention of the Act, or that a person 
 on board is suffering from an infectious disease, he may enter the 
 boat for the purpose of inspection between 6 a.m. and 9 p.m., 
 and may require the master or whoever is in charge of the boat 
 to afford him facilities for so doing, and to produce the certificate 
 of registry of the boat (sec. 5, Act of 1877). 
 
 Sec. 2 of the Act of 1877 directs the M.H. to make regula- 
 tions : — (i) for the registration of canal boats ; (ii) for lettering, 
 marking, and numbering such boats ; (lii) for fixing the number, 
 age, and sex of persons who may be allowed to dwell in a canal 
 boat, having regard to the cubic space, ventilation, separation of 
 the sexes, general healthiness, and convenience of accommoda- 
 tion; (iv) for promoting cleanliness and habitable condition of 
 such boats ; and (v) for preventing the spread of infectious 
 disease by canal boats. 
 
 In pursuance of the above powers, an Order was issued in 
 1878, prescribing a series of regulations which are still in force. 
 The following is a summary of their principal sanitary pro- 
 visions : — 
 
 " There must be at least one dry, clean, and weather-proof 
 cabin in good repair. An after-cabin, intended to be used as a 
 dwelling, must contain not less than 180 cubic feet of free air 
 space, and a fore-cabin 80 cubic feet ; every such cabin must 
 have means of ventilation besides the door, and must be so 
 constructed as to provide adequate sleeping accommodation. 
 
VANS AND TENTS. S°7 
 
 One cabin must contain a stove and chimney. The boat must 
 be furnished with suitable storage for three gallons of water. If 
 intended to be ordinarily used for foul cargoes, the hold must be 
 separated from any inhabited cabin by a double bulk-head with 
 an interspace of 4 inches, and the bulkhead next the cargo 
 must be water-tight. Not less than 60 cubic feet of air space 
 must be allowed for each person over twelve years of age, and 
 not less than 40 cubic feet for each person under that age. In 
 4 fly-boats ' worked by shifts, a cabin occupied at the same time 
 by two persons must have a capacity of 180 cubic feet. A cabin 
 in which a married couple sleep must not be occupied at the same 
 time by any other male above fourteen, or female above twelve 
 years of age. Males above fourteen and females above twelve 
 years of age must not occupy the same sleeping-cabin at the 
 same time, but reservation is made for married couples, and 
 also (under certain conditions) in respect of boats constructed 
 prior to 1878. The interior of the cabin must be repainted 
 every three years, and must be kept clean. Bilge water must 
 be pumped out daily. The master of the boat must at once 
 notify the occurrence of any case of infectious disease on the 
 boat to the S.A. of the district through which the boat may be 
 passing, and also to the S.A. of the place of destination ; he 
 must also inform the owner, who is required to notify to the S.A. 
 of the place to which the boat belongs. If the boat is detained 
 by the authority for purposes of disinfection, the S.A. must 
 obtain a medical certificate that the boat has been cleansed and 
 disinfected, and shall cause such certificate to be delivered to the 
 master of the boat, who cannot proceed until that certificate has 
 been obtained. The S.A. may pay a reasonable remuneration 
 for any such certificate." 
 
 The Acts contain special provisions with respect to the 
 education of children living in canal boats, and enable the 
 Education Department to make regulations on this subject 
 (sees. 6 and 12, Act of 1877). Sec. 4 of the Act of 1884 
 requires the M.H. to make inquiries, from time to time, by 
 an inspector or inspectors, specially appointed for the purpose, 
 as to the working of these Acts and Regulations, and to report 
 annually thereon to Parliament. 
 
 Vans and Tents. — To control the sanitation of the more or 
 less vagrant population occupying movable dwellings other than 
 canal boats, every S.A. possesses certain powers under the 
 P.H.A., 1875, under the unrepealed 9th and 10th sees, of the 
 H.W.C.A., 1885, and under the P.H. (Fruit-Pickers) A., 1882. 
 
 Sec. 9 of the H.W.C.A., 1885, provides that a tent, van, shed, 
 or similar structure, used for human habitation (exclusive of those 
 
508 SANITARY LAW. 
 
 used by a portion of his Majesty's military or naval forces), which 
 is in such a state as to be a nuisance or injurious to health, 
 or which is so overcrowded as to be injurious to the health of 
 the inmates, whether or not members of the same family, shall 
 be deemed to be a nuisance within the meaning of sec. 91 of 
 the P.H.A., 1875, and the provisions of that Act shall apply 
 accordingly. By sec. 10, any S.A. may make bye-laws in regard 
 to such habitations. Power of entry between 6 a.m. and 9 p.m. 
 is given to any person duly authorized by the S.A. or by a Justice 
 of the Peace, if such person has reasonable cause to suspect any 
 contravention of the Act, or of any bye-laws made under it, or 
 that there is in such habitation any person suffering from any 
 dangerous infectious disease. If any such person is obstructed 
 in the performance of his duty under the above provisions, the 
 person obstructing him will be liable on summary conviction to a 
 fine not exceeding 40s. 
 
 As regards the accommodation and lodging of hop- and fruit- 
 pickers, every S.A. has power under sec. 314 of the P.H.A., 
 1875, t0 ma ke bye-laws for securing the decent lodging and 
 accommodation of persons engaged in hop-picking within the 
 district of such authority. This power has been extended by the 
 Fruit-Pickers' Act of 1882, so as to enable the same authorities to 
 make bye-laws for securing decent and proper accommodation 
 and lodging of those engaged in the picking of fruit and 
 vegetables. 
 
 For the proper control and regulation of the tents, sheds, 
 barns, or other places occupied as temporary dwellings by hop- 
 pickers and others, but not of places inhabited throughout the 
 year, the Model Bye-laws have been promulgated. Of these, 
 the following is a brief summary : — 
 
 " (a) The habitations must be clean, dry, weather-proof, 
 ventilated, and lighted, (b) At least 16 square feet of floor space 
 must be allowed in them for each adult and for every two children 
 under ten years of age. (c) When intended for the reception 
 of adults of different sexes, the habitations must be so furnished 
 or provided that every bed is properly separated from any 
 adjoining bed by a suitable screen or partition to secure 
 adequate privacy to the occupants, (d) There must be a 
 separate cooking-place for every fifteen persons authorized to 
 be received, (e) There must be a sufficient supply of good 
 water for drinking, cooking, and washing. (/) There must 
 be adequate privy accommodation for the separate use of each 
 sex. (g) Every lodger or occupant shall be provided with a 
 sufficient supply of clean dry straw, or other clean, dry, and 
 suitable bedding, which must be changed or properly cleansed 
 
CELLAR DWELLINGS. 509 
 
 "rom time to time, as occasion may require, (k) Every part of 
 ;he interior of the premises, the cook-houses, and privies must 
 )e thoroughly cleansed immediately before any person is 
 •eceived to lodge therein, the internal surfaces limewashed, and 
 ill offensive accumulations cleared away; this cleansing and 
 imewashing must be done at least annually and repeated as 
 •equired from time to time during the period of occupation." 
 
 Cellar Dwellings. — Sec. 71 of P.H.A., 1875, prohibits the 
 separate occupation as a dwelling of any cellar built or rebuilt 
 ifter the passing of the Act, or which was not lawfully so let or 
 Kcupied at the time the Act was passed. Any one passing the 
 light in a cellar is deemed to occupy it (sec. 74). 
 
 Cellar dwellings, the letting or occupation of which are not 
 orbidden under sec. 71, are prohibited by sec. 72 from 
 )eing let or occupied unless they comply with the following 
 equirements : — (a) The height must in every part be at least 
 j feet, 3 feet of which must be above the level of the adjoining 
 itreet. (b) An open area at least 2\ feet wide in every part, and 
 > inches below the level of the floor, must extend along the whole 
 rontage. It may be crossed by steps, but not opposite the 
 vindow. (c) The cellar must be drained by a drain at least 
 [ foot below the floor, (d) There must be proper closet and 
 ishpit accommodation, (e) There must be a fireplace and 
 :himney, and (f) a window at least 9 square feet in area, made 
 o open. The window of a back cellar let or occupied along 
 vith a front cellar need only be 4 square feet in area. 
 
 Any person who lets, occupies, or knowingly suffers to be 
 )ccupied for hire or rent any cellar contrary to the Act is liable 
 "or every offence to a penalty not exceeding 20s. for every day 
 )f default (sec. 73). Where two convictions relating to the 
 xxupation of a cellar as a separate dwelling have taken place 
 vithin three months, a Court of Summary Jurisdiction may close, 
 iither temporarily or permanently, the premises, as it deems to 
 )e necessary (sec. 75). 
 
 In the Metropolis, the provisions as to cellar dwellings by 
 >ecs. 96 to 98 of the P.H. (London) A., 1891, differ some- 
 what from those given in the preceding section. A cellar dwelling 
 Dr underground room must not be occupied in London unless : — 
 [a) Every part is 7 feet high, and the ceiling is at least 3 feet 
 ibove the surface of the adjoining street ; but if the area outside 
 is as much as 6 feet in width, or not less wide than the depth 
 of the floor below the ground level, then the height may be 1 foot 
 above the street, (b) Every wall has a damp-course, and, if in 
 contact with the soil, is effectually secured from damp from the 
 soil, (c) There is an open area outside along the frontage, 
 
5IO SANITARY LAW. 
 
 ^feet wide in every part, and 6 inches below the floor level. It 
 may be crossed by steps, but not opposite a window, (d) The 
 area and the soil immediately below the room are effectually 
 drained, (e) The hollow space (if any) below the floor is ven- 
 tilated to the outer air. (/) Any drain passing under, the room 
 is properly constructed of gas-tight pipe, (g) The room is 
 effectually secured against the rising of any effluvia or exhalation. 
 (h) There is a proper water-closet and ashpit in a convenient 
 place. (/') There is effectual ventilation. (J) There is a fire- 
 place, with chimney, (k) There are one or more windows 
 opening directly into the open air ; the window-area being at 
 least one-tenth of the floor area, and so constructed that at least 
 half of each window can be opened, and in each case opening 
 to the top. 
 
 The same conditions apply to underground rooms occupied 
 separately as dwellings before January i, 1892 ; but the S.A., 
 either by general regulations or upon special application by the 
 owner,' may modify any conditions newly imposed by this Act 
 which involve structural alteration of the building. The power 
 as to closure of underground rooms after two convictions is the 
 same as under the 1875 Act. 
 
 Common Lodging-houses. — The expression " common lodging- 
 house" is taken to mean, for the purposes of the P.H.A., 1875, 
 those lodging-houses " in which persons of the poorer class are 
 received for short periods and, though strangers to each other, 
 are allowed to inhabit one common room." The term does not 
 include inns, nor lodgings let to the middle or upper classes. 
 Sec. 76 of P.H.A., 1875, requires every S.A. to keep a 
 register of common lodging-houses in their district, in which 
 shall be entered the names and addresses of the keepers thereof, 
 and the situation of every such house, and the number of persons 
 authorized by such authority to be received therein. Under the 
 P.H.A. (Amend.) A., 1907, the S.A. can refuse the registration 
 of a common lodging-house keeper, notwithstanding the produc- 
 tion of a certificate signed by three ratepayers. Further, the S.A. 
 must keep a register of keeper's deputies. The registration of 
 keepers and their deputies needs renewal annually. No common 
 lodging-house can be kept unless registered, and this can only 
 be done after inspection and approval by some officer of the 
 S.A. (P.H.A., 1875, sees. 77, 78). Before premises are so 
 approved they should " (1) Possess the conditions of wholesome- 
 ness needed for dwelling-houses in general ; and (2) should have 
 arrangements fitting it for its special purpose of receiving a 
 number of lodgers." Thus, the house should have dry founda- 
 tions, and have proper drainage, guttering, and spouting, with a 
 
COMMON LODGING HOUSES. 5 1 1 
 
 well-laid and paved yard abutting on it. The drains must be 
 properly connected, the soil-pipe ventilated, the water-closets 
 trapped, and all waste-pipes from sinks, basins, etc., discharging 
 Dver gullies outside the house. The closets, privies, and recep- 
 tacles should be in convenient situations, of proper construction, 
 ind adapted to the scavenging arrangements of the district. The 
 svalls, roof, and floors should be in good repair. Inside walls 
 should not be papered. Every registered room should have 
 special means of ventilation, by chimney if possible, and a 
 vindow opening freely and directly upon the outer air. There 
 should be kitchen and day-room accommodation apart from the 
 bedrooms. Rooms partially underground should not be registered 
 is sleeping-rooms. There should be a supply of pure water, 
 illowing at least 10 gallons per head per day for the maximum 
 lumber of inmates, and one closet for every 20 registered 
 odgers. The washing accommodation should, wherever practi- 
 cable, be in a special place, and not in the bedrooms ; the basins 
 or personal washing being fixed, trapped, and fitted with dis- 
 connected waste-pipes. 
 
 All common lodging-houses must have their walls and ceilings 
 imewashed in the first weeks of April and October in each year 
 sec. 82). Free access must be allowed to officers of the 
 5.A. to all parts of a common lodging-house. Under sec. 80 
 P.H.A., 1875, ever y S.A. must make bye-laws for the sani- 
 ary control and management of common lodging-houses : 
 he following is a summary of the models issued :— 
 
 " (a) A greater number of lodgers than the maximum from 
 ime to time fixed by the S.A. by a notice served on the keeper of 
 he house must not be accommodated in each room ; it is usual 
 o require at least 300 cubic feet of air space per head, but to 
 ount two children as one adult, (b) In general, no person above 
 to years of age must occupy the same sleeping-room as persons 
 )f the opposite sex, but rooms may be set apart for the sole use 
 >f married couples, to the exclusion of other persons over 10 years 
 )f age, on condition that every bed is screened off. No bed 
 nust be occupied by more than one male above 10 years of age. 
 
 c) The yards, etc, must be kept clean and in good order; all 
 loors swept daily, and washed once a week ; all windows, painted 
 surfaces, and fittings of wood, stone, or metal kept clean. 
 
 d) Closets must be kept clean and in good and efficient order. 
 >) Ashpits must be kept clean and in good order ; no filth or 
 vet refuse being thrown into ashpits designed for dry refuse only. 
 '/) The windows must be opened fully for an hour in the 
 norning and an hour in the afternoon, except in case of bad 
 veather or occupation of the room by a sick person, or other 
 
512 SANITARY LAW. 
 
 sufficient cause. Beds must be stripped of clothes and fully 
 exposed to the air for an hour each day, and must not be re- 
 occupied within 8 hours after being vacated. All refuse and 
 slops must be removed every day before 10 a.m., and all utensils 
 cleansed daily. Every sleeping-room must be provided with 
 sufficient bedsteads, beds, bed-clothes, and utensils for the use 
 of the maximum number of lodgers to be received therein, (g) A 
 sufficient supply of suitable basins, water, and towels must be 
 provided for the use of lodgers, and must be kept clean and 
 renewed as required, (h) If the keeper finds that any lodger is 
 suffering from an infectious disease, he must at once take all 
 necessary precautions. No person, except a relative or attendant, 
 must occupy the same room as the sick person. If the patient 
 is removed to hospital by the S.A., the keeper must afford all 
 facilities for removal, and must adopt all precautions directed by 
 the M.O.H. He must, if required to do so, temporarily cease 
 to receive lodgers into any infected room. At the end of the 
 case, by removal, recovery, or death, the keeper must at once 
 give notice to the M.O.H., and must cleanse and disinfect every 
 part of the infected rooms and their contents, and in doing so 
 must comply with all the instructions of the Health Officer. 
 When the cleansing and disinfection are completed, he must give 
 notice thereof to the M.O.H. , and must not receive any lodger 
 into the rooms in question until two days after such notice has 
 been given. (/) A copy of the bye-laws in force with respect to 
 common lodging-houses, supplied by the S.A., and a statement 
 of the provisions of sees. 75 to 89 of the P.H.A., 1875, must 
 be placed in some conspicuous place in the house, and must not 
 be concealed, altered, obliterated, or injured." If the keeper of 
 a common lodging-house fails to give notice of the occurrence of 
 any infectious disease, he is liable to a penalty under sec. 84 
 of P.H.A., 1875. As regards houses let in lodgings or occupied 
 by members of more than one family, any S.A. may make bye- 
 laws, under sec. 90 P.H.A., 1875, as modified by sec. 8 of 
 H.W.C.A., 1885. 
 
 Housing of Working Classes. — A considerable amount of 
 legislature exists as to this question. Under the H.W.C.A., 
 1885, every S.A. must exercise powers which they possess under 
 the P.H.A., 1875, to secure a proper sanitary condition of all 
 premises within their area. Powers of entry to inspect suspected 
 premises between the hours of 6 a.m. and 9 p.m. is given to any 
 person authorized by the S.A. or by a magistrate, by sec. 9, 
 H.W.C.A., 1885. As regards the pulling down of unhealthy 
 areas, full powers are given by Part i. of H.W.C.A., 1890. After 
 complaint, inspection is to be made, and due publicity given as to 
 
HOUSING OF WORKING CLASSES. 5 1 3 
 
 ny scheme of amendment. If the scheme be confirmed by the 
 -I.H., application is made to Parliament for a provisional order, 
 ifter this order is confirmed by Parliament, it is executed by the 
 5.A., who must take care to adjudicate claims for compensation, 
 .nd, if necessary, submit them to arbitration. In London ac- 
 :ommodation must be provided in or near the area for the whole 
 >opulation displaced, unless the provisional order decrees other- 
 vise ; outside the metropolis such provision is only compulsory if 
 .nd to the extent provided by the order. 
 
 As regards unhealthy or obstructive buildings, similar powers 
 re given and to be carried out, subject to the concurrence of 
 £.H., under Part ii. of the H.W.C.A. , 1900. In rural districts, 
 nformation of proceedings about to be taken must be sent to the 
 bounty Council by a S.A. instigating proceedings for either closing 
 >r demolition. Similarly, a County Council can compel a S.A. 
 proceed, or can take over and exercise the powers of a S.A. 
 ailing to act, and recover expenses from the S.A. concerned. 
 Jnder House, Town Planning Act, 1909, it is compulsory on 
 LA. to adopt Part iii. of the H.W.C.A., 1890, formerly adoptive. 
 rhis authorizes every S.A. to provide lodging-houses for the 
 working-classes, subject to sanction of M.H., in urban districts, 
 nd the County Council in rural. The H.W.C.A., 1900 and 1903, 
 leal with and simplify the terms on which the S.A. acquire land 
 or improvement of this kind. Under H.T.P.A., 1909, the 
 acilities for acquiring land are still further increased, and its 
 ►bject is to ensure, by schemes prepared by the S.A. or land- 
 iwner, that land in the vicinity of towns shall be developed in 
 uch way as to secure proper sanitary conditions and convenience 
 n connection with laying out of land and building thereon. Its 
 ssential feature and object is to improve the relations between 
 andowners and the S.A., and also to enable each to co-operate 
 rith the other in promoting the public interests. 
 
 A recent amplification of the foregoing legislation is the 
 lousing and Town Planning Act of 1919. It applies to England 
 nd Wales, and orders every S.A. to prepare and submit, within 
 hree months after notice by M.H., a scheme under Part iii. of 
 be principal Act, 1900, specifying the approximate number and 
 ature of houses to be provided by the local authority, the 
 pproximate quantity of land required, the average number of 
 ;Ouses per acre, the cost and time within which the scheme is to 
 e completed. S.A.'s may make joint schemes. The M.H. may 
 pprove or modify the schemes as they think fit. In the case of 
 lefaulting local authorities, the County Council may be authorized 
 d act and charge expenses to the defaulting S.A. Under these 
 chemes, existing bye-laws may be relaxed if plans and specifica- 
 
 s 
 
5 14 SANITARY LAW. 
 
 tions are approved by the M.H. The powers under P.H.A., 
 1875, which refer to houses let in lodgings shall, in the case of 
 houses so occupied by the working classes, be extended so as to 
 provide for adequate or separate provision for each family of- 
 w.c. accommodation, water supply, and washing facilities, accom- 
 modation for storage, preparation, and cooking of food. Also for 
 adequate lighting and keeping in repair any common stair, the 
 provision of handrails for all staircases, prevention and safety 
 from fire, the adequate lighting of any room, paving of courts or 
 yards, and cleaning or redecoration at stated times. On applica- 
 tion by a S.A. a county court may authorize conversion of a 
 house into several tenements, notwithstanding any restrictive 
 covenant. 
 
 Factories and Workshops. — The general effect of the 
 Factories and Workshop Act, 1901, is to place all factories and 
 workshops under a dual control, namely, the Home Office and the 
 various sanitary authorities. The Home Secretary appoints 
 factory inspectors, whose primary duty is to inspect factories , 
 while the primary duty of inspecting workshops and workplaces 
 rests with the S.A. 
 
 By the Factory and Workshop Act, 1901, factories include (1) 
 all places in which mechanical power is used in aid of the manu- 
 facturing process ; and (2) the following, whether power be used 
 or not : — print-works, bleaching and dye-works, earthenware 
 works, lucifer-match works, percussion-cap works, cartridge 
 works, paper-staining works, fustian-cutting works, blast-furnaces, 
 copper mills, iron mills, foundries, metal and india-rubber 
 works, paper mills, glass-works, tobacco factories, letterpress 
 printing works, bookbinding works, flax scutch mills, electrical 
 stations. 
 
 Factories and workshops, be they wholesale, retail, or sub- 
 contracting, may be (1) those in which "protected persons" are 
 employed, that is, a child under 14 or a young person over 14 
 but under 18, or a woman over 18 years of age; (2) those in 
 which "protected persons" are not employed; (3) tenement 
 factories or workshops ; and (4) domestic factories and workshops. 
 
 A "tenement factory" is one in which mechanical power is 
 supplied to different parts of the same building occupied by 
 different persons, for the purpose of any manufacturing process 
 or handicraft in such manner that these parts constitute in law 
 separate factories. 
 
 Domestic factories and Domestic workshops are those carried on 
 in private houses, without use of mechanical power, where the 
 only persons employed are members of the same family dwell- 
 ing there. If any work certified by the Home Secretary to be 
 
FACTORIES AND WORKSHOPS. 5 1 5 
 
 langerous is carried on, they are treated as ordinary factories and 
 workshops ; otherwise they are, so far as sanitation is concerned, 
 .reated as ordinary workshops, except that the requirements as to 
 general ventilation and drainage of floors do not apply. The 
 "ollowing, if carried on under conditions which would otherwise 
 nake thf premises a domestic workshop, are exempted : — (1) 
 Straw-plaiting, pillow-lace making, glove-making ; (2) work done 
 it irregular intervals, and not furnishing the principal means of 
 iving to the family. 
 
 Workshops include (1) the following, unless they are factories 
 )y reason of the use of mechanical power : — hat-works, rope- 
 vorks, bakehouses (any places in which are baked bread, biscuits, 
 )r confectionery, from the baking or selling of which a profit is 
 lerived), lace warehouses, ship-building yards, quarries, pit-banks 
 )f metalliferous mines, dry-cleaning works, carpet-beating works, 
 ind bottle-washing works ; (2) premises (not being factories) in 
 vhich manual labour is exercised by way of trade or for purposes 
 }f gain, in or incidental to the making, altering, repairing, orna- 
 nenting, finishing or adapting for sale of any article, if the em- 
 ployer has the right of access or control ; (3) tenement work- 
 shops ; that is, workplaces in which, " with the permission of or 
 inder agreement with the owner or occupier, two or more persons 
 :arry on any work which would constitute the workplace a work- 
 shop if the persons working therein were in the employment of 
 :he owner or occupier." Instances of tenement workshops are 
 ;he Sheffield file-cutting shops, where file-cutters work on their 
 )wn account; also journeymen tailors' workshops, where men 
 lire a separate sitting or place to work from the owner or 
 )ccupier. 
 
 Men's workshops (those in which only males over eighteen are 
 employed) are exempted from several of the provisions of the 
 Act, including those relating to general ventilation, temperature, 
 drainage of floors, sanitary accommodation, lavatories, fans for 
 removal of dust or fumes, and means of escape from fire. 
 
 Crown factories and workshops are excluded from the juris- 
 diction of the S.A. 
 
 Workplace is not defined, but has a wider meaning than 
 workshop, and has been held to include any place where people 
 assemble together to do work permanently, e.g. a stable and 
 stable-yard, where men are employed as cab-cleaners and horse- 
 keepers. 
 
 In factories, sanitation generally is enforced by the Factory 
 Inspector, not by the District Council, hereafter referred to as the 
 Sanitary Authority, but the latter deals with the means of escape 
 from fire (in London this rests with the County Council), and have 
 
516 SANITARY LAW. 
 
 special duties in connection with bakehouses and domestic fac- 
 tories, as well as with sanitary accommodation under sec. 9 of 
 the Factory Act, 1901, also under sec. 38 of the P.H.A., 1875, 
 and where Part III. of the P.H. (Amend.) A., 1890, is in 
 force, under sec. 22 of that Act. If any act or default, punish- 
 able or remediable under the P.H. A., but not under the 
 Factory Act, is found by the Factory Inspector in a factory or 
 workshop, he is to report it to the S.A., who must make inquiry, 
 take such action as may seem proper, and inform the Factory 
 Inspector what has been done. If proceedings are not taken 
 by the S.A. within a month, the Factory Inspector may 
 institute proceedings in default, and recover from the S.A. any 
 expenses not recovered from other persons, and not incurred in 
 unsuccessful proceedings (sec. 5). If the S.A. fail generally to 
 carry out their duties with regard to factories, workshops, or work- 
 places, the Home Secretary may authorize the Factory Inspector 
 to act in default for a specified period, and the expenses not 
 recovered from other persons may be recovered from the S.A. 
 
 In workshops and workplaces the S.A. (sees. 2, 3, 4 and 5) 
 is primarily responsible for enforcing sanitary requirements 
 generally, and means of escape from fire ; and their officers have 
 the same powers of entry, inspection, and legal proceedings as 
 Inspectors of Factories. Certain sanitary requirements, however, 
 more particularly those relating to temperature, fans for removal 
 of dust and fumes, and those arising under the Factory Act 
 (as distinguished from the powers of the S.A. under the 
 P.H. A., 1875) with regard to sanitary accommodation are en- 
 forced by the Factory Inspectors. The S.A. is required to keep 
 a register of all workshops in its district (sec. 131). If the 
 M.O.H. finds any woman, young person, or child employed in 
 a workshop in which no abstract of the Factory Act is affixed, he 
 is required to inform the Factory Inspector. The occupier of a 
 new factory, workshop, or laundry must notify the Factory In- 
 spector, who, in the case of a workshop, forwards the notice to 
 the S.A. 
 
 The M.O.H. (under sec. 132) is required in his annual 
 report to report specifically upon the administration with regard 
 to workshops and workplaces, and to send a copy to the Home 
 Secretary. A table issued by the M.H. for the guidance of the 
 M.O.H., includes the items calling for statistical record. 
 
 Outside the Factory Act, the S.A. is concerned with certain 
 factories and workshops on public health grounds, as sources of 
 smoke, poisonous fumes, trade effluents ; as places where offen- 
 sive trades or food manufacture needing control are carried on ; 
 as new buildings needing approval of plans, or old buildings in a 
 
FACTORIES AND WORKSHOPS. 517 
 
 dangerous state; or more indirectly as places in which infection 
 may be spread from one person to another, or (as in laundries) 
 infected articles may be handled. Nor are these the only points 
 claiming the attention of the various officials of the S.A. in 
 connection with plans for new factories and workshops. Others 
 are strength of foundations and structure generally where heavy 
 machinery is to be fixed ; means of escape from fire ; sanitary 
 accommodation. Others, again are the statutory requirements as 
 to air space, ventilation and warming ; the surfaces of walls and 
 ceilings must be such as to admit of due cleansing, and the proper 
 construction of floors (soundness, impermeability, slope, drainage) 
 is of importance in certain processes. In certain dangerous 
 trades additional structural requirements arise, and in some the 
 plans have also to be approved by the Chief Inspector of 
 Factories. 
 
 The requirements of the Factory and Workshop Act, 1901, in 
 the above-mentioned matters, and which it is the duty of the 
 S.A. to enforce, are as follows : — 
 
 Cleanliness. — By sec. 2 every workshop and workplace must be 
 kept in a cleanly state, and if not so kept may be dealt with as a 
 nuisance under the P.H.A. A workshop or any specified part 
 thereof (in London this power extends to domestic factories and 
 to workplaces, P.H. (L.) A v 1891, sec. 25) must be limewashed, 
 cleansed or purified when so required, by notice from the S.A., 
 on the certificate of the Medical Officer or Sanitary Inspector that 
 it is necessary for the health of the workers. All factories must be 
 kept in a cleanly state, and (subject to certain exceptions) either 
 (a) limewashed every fourteen months, or (b) painted with oil or 
 varnished every seven years, and washed with soap and hot water 
 every fourteen months. For the cleaning of floors, etc., damp 
 processes are preferable, as checking the production of dust. 
 
 Air Space. — Factories, workshops and workplaces (sees. 2 
 and 3) must not be so overcrowded as to be dangerous or inju- 
 rious to the health of the workers, and there must be at least 250 
 cubic feet of air space for each worker; during overtime for 
 women 400 cubic feet must be provided, 500 cubic feet in under- 
 ground bakehouses, 400 cubic feet between 9 p.m. and 6 a.m. in 
 other bakehouses with light other than electric, 400 cubic feet in 
 workshops (not domestic) used also as sleeping-rooms. The air 
 space of each workroom must be stated in a notice affixed in the 
 works. A much larger air space is required in certain dangerous 
 trades, and in works where certain special exceptions are per- 
 mitted, e.g. in match factories in which yellow phosphorus is used 
 the minimum is 400 cubic feet, and height above 14 feet is not 
 counted, and in engineering works exemption from routine 
 
518 SANITARY LAW. 
 
 annual limewashing is allowed if the air space be 2500 cubic feet 
 per head. 
 
 General Ventilation (sec. 7) must be efficient in every 
 workroom of a factory or workshop (other than a men's work- 
 shop), and any standard fixed by the Home Secretary must be 
 observed ; thus, a limit of 9 volumes of carbon dioxide per 
 10,000 of air in humid cotton-cloth factories is required, and 600 
 cubic feet of fresh air per head per hour must be supplied in other 
 humid textile factories. Air samples are taken usually at the 
 breathing-level, at points when work is carried on, and not in 
 extreme corners or near to inlets or outlets, or close to persons or 
 to sources of carbon dioxide. In breweries, aerated water 
 factories, bakehouses, etc., where carbonic acid is given off by 
 trade processes, allowance has to be made ; and similarly where 
 artificial lighting yields carbon dioxide. As a rule, it is well to 
 make a parallel determination in the open air. 
 
 Local Ventilation, for removal of dust, gases, vapours, or other 
 impurities generated in the course of work, which are a nuisance 
 or injurious to health, must be such as to render them harmless as 
 far as possible. Usually this involves exhaust ventilation, applied 
 at or near the point of origin ; and fans (or other efficient 
 mechanical means) for the purpose are prescribed in certain 
 dangerous processes, and can be required by the Factory 
 Inspector in others. Exhaust ventilation may sometimes be 
 secured by connection with flues or other heated shafts, but in, 
 general fans are required, and need careful planning. The 
 essentials are that the dust or fumes should be intercepted as near 
 as possible to their source, and carried away from the workers, 
 without entering the general air of the room ; that the draught 
 should be adequate for the purpose, and guided where necessary 
 by hoods ; and that the air-ducts should be kept clean and dis- 
 charge at a suitable point, preferably in a closed dust-chamber. 
 As a rule, a downward draught is best, since it carries away the 
 dust more readily. The efficiency of exhaust can be tested by 
 anemometers or by smoke, light dust, or fumes of ammonium 
 chloride. In some instances, standards are fixed, in terms of 
 sectional area of openings and velocity at given points. Other 
 measures are the use of closed chambers or boxes, and as regards 
 dust the adoption of wet processes, handling the dusty materials 
 over gratings through which the dust can fall, cleanliness of 
 premises and floors, and the use of overalls. 
 
 Temperature. — In every workroom of a factory or workshop 
 provision must be made for securing a reasonable temperature 
 (sec.' 6), and without interfering with the purity of the air of the 
 room. This requirement is enforced by the Factory Inspector. 
 
FACTORIES AND WORKSHOPS. 519 
 
 ras-jets cannot be accepted as means of warming, nor must the 
 ventilators be closed. As a lower limit 6o u F. is suitable for 
 edentary occupations, but active work can be carried on at a 
 ower temperature. The upper limit is not easily denned, since in 
 :ertain processes a high temperature is a trade necessity, while in 
 >thers it is only accidental. In humid cotton-cloth factories it is 
 orbidden to raise the temperature artificially above 70 F., 
 ixcept so far as is necessary for moistening the air. If the air be 
 Iry, high temperatures can be borne, but as a rule where work is 
 lard, high wet-bulb temperatures should be avoided. Humidity 
 5 expressly regulated in textile factories generally, such as spin- 
 ling- and weaving-sheds where the air is moistened by steam jets 
 ►r otherwise to facilitate the efficient working and treatment of 
 he cotton fibres. In these places a limit of humidity is fixed for 
 :ach dry-bulb degree, thus 88 per cent, from 59 to 70 F. t 
 lecreasing thence to 77*5 per cent, at 8o° F., 69 per cent, at 90 
 ?., and 64 per cent, at ioo° F. In certain textile processes, 
 lowever, a difference of 2 between wet and dry bulbs is accepted 
 t all temperatures. Hygrometers must be affixed in each room, 
 .nd (except in cotton-spinning mills), records kept of two (in 
 otton-cloth factories three) daily readings at 7 to 8 a.m., 10 to 
 1 a.m. and 3 to 4 p.m. The water used for humidification must 
 ie taken either from a pure source or be effectively purified ; a 
 rater which gives off an offensive smell on being heated, or 
 fhich absorbs more than 0*5 mgm. of oxygen from an acid 
 olution of potassium permanganate in two hours at 6o° F. is to 
 ie regarded as unsuitable. Owing to the clothing of workers 
 lecoming damp in moist air warmed ventilated cloak rooms are 
 •bligatory in new-built humid cotton weaving sheds. 
 
 Sanitary Accotnmodatlori. — The following are the provisions 
 nade in regard to these matters by an Order of the Home 
 Secretary, under sec. 9 of the Act : — 
 
 " 1. In factories or workshops where females are employed or 
 a attendance there shall be one sanitary convenience for every 
 wenty-five females. 
 
 " In factories or workshops where males are employed or in 
 ttendance there shall be one sanitary convenience for every 
 vventy-five males; provided that (a) in factories or workshops 
 mere the number of males employed or in attendance exceeds 
 >ne hundred, and sufficient urinal accommodation is also pro- 
 ided, it shall be sufficient if there is one sanitary convenience 
 or every twenty-five males up to the first hundred and one for 
 very forty after ; {b) in factories or workshops where the number 
 »f males employed or in attendance exceeds five hundred, and 
 he district Inspector of Factories certifies in writing that by 
 
520 SANITARY LAW. 
 
 means of a check system, or otherwise, proper supervision or 
 control in regard to the use of the conveniences are exercised by 
 officers specially appointed for that purpose, it shall be sufficient 
 if one sanitary convenience is provided for every sixty males, in 
 addition to sufficient urinal accommodation. Any certificate 
 given by an Inspector shall be kept attached to the general 
 register, and shall be liable at any time to be revoked by notice 
 in writing from the Inspector. In calculating the number of 
 conveniences required by this Order, any odd number of persons 
 less than twenty five, forty, or sixty, as the case may be, shall be 
 reckoned as twenty-five, forty, or sixty. 
 
 " 2. Every sanitary convenience shall be kept in a cleanly 
 state, shall be sufficiently ventilated and lighted, and shall not 
 communicate with any workroom except through the open air or 
 through an intervening ventilated space ; provided that in work- 
 rooms in use prior to January i, 1903, and mechanically 
 ventilated in such manner that air cannot be drawn into the 
 workroom through the sanitary convenience, an intervening 
 ventilated space shall not be required. 
 
 " 3. Every sanitary convenience shall be under cover and so 
 partitioned off as to secure privacy, and if for the use of females, 
 shall have a proper door and fastenings. 
 
 " 4. The sanitary conveniences in a factory or workshop shall 
 be so arranged and maintained as to be conveniently accessible 
 to all persons employed therein at all times during their employ- 
 ment 
 
 " 5. Where persons of both sexes are employed, the con- 
 veniences for each sex shall be so placed or so screened that the 
 interior shall not be visible, even when the door of any con- 
 venience is open, from any place where persons of the other sex 
 have to work or to pass ; and, if the conveniences for one sex 
 adjoin those for the other sex, the approaches shall be separate." 
 
 Safety from Fire. — By sees. 14 and 15 it is the duty of a 
 District Council, and in London the duty of the County Council, 
 to see that every factory and workshop in its district is provided 
 with sufficient means of escape in case of fire. 
 
 Home Work. — Very important powers of controlling the con- 
 ditions under which certain classes of work are done in the homes 
 of the workers are given to S.A. by sees. 107 to 115 of the 
 Factory Act, 1901. These powers aim at the prevention of 
 home work being done (1) in dwellings which are injurious or 
 dangerous to the health of the workers themselves; (2) in 
 premises where there is infectious disease. The employer must 
 keep lists of the names and addresses of the out-workers, and 
 send copies to the S.A. of his district on or before February 1 
 
FACTORIES AND WORKSHOPS. 521 
 
 and August i of each year, in a prescribed form. If any such 
 addresses are outside the area of the authority, particulars of 
 them must be sent by the S.A. to the authority concerned. If 
 the home premises are injurious or dangerous (overcrowding, 
 want of ventilation, or other insanitary condition) to the health 
 of the workers, the S.A. may prohibit the employer giving out 
 the work to be done there. This power may be exercised also 
 in the case of work given out from places other than factories or 
 workshops, as, for instance, shops, warehouses or laundries. The 
 power does not apply to all classes of home work, but only to 
 those which may be specified by Orders of the Home Secretary. 
 The trades scheduled by Orders of August, 1905, and May, 1907, 
 and to which the power is rendered applicable, are the following 
 classes of work : the making, cleaning, washing, altering, ornament- 
 ing, finishing and repairing of wearing apparel, and any work 
 incidental thereto ; the making, ornamenting, mending and finish- 
 ing of lace, and of lace curtains and nets ; cabinet and furniture 
 making and upholstery work ; the making of electro-plate ; the 
 making of files ; fur-pulling ; the making of iron and steel cables 
 and chains ; the making of iron and steel anchors and grapnels ; 
 the making of cart-gear, including swivels, rings, loops, gear- 
 buckles, mullin-bits, hooks, and attachments of all kinds ; the 
 making of locks, latches, and keys ; the making of covers for and 
 finishing of umbrellas, sunshades, parasols; the making of card- 
 board or paper boxes and paper bags; brush making and the 
 making of stuffed toys ; the making of artificial flowers, or pea 
 picking and feather sorting. Wearing apparel and upholstery 
 may not be made, cleansed, or repaired by out-workers in any 
 house where there is a case of small-pox or scarlet fever. If an 
 inmate of a house is suffering from a notifiable infectious disease, 
 no matter if removed, the S.A. can prohibit the employer from 
 giving out work in respect of any of the foregoing scheduled 
 classes of work to be done in that home or house, or in any 
 specified part of it, during a specified period. 
 
 An out-worker is one who works outside the factory, that is, 
 receives work from a factory to do at home or in another work- 
 shop. He is also called a home-worker. The M.O.H. must give 
 notice to the Factory Inspector for the district of any " protected 
 person " employed in a workshop. Lists giving the names and 
 addresses must be kept by occupiers of factories or workshops of 
 all out-workers, and these lists sent to the factory inspector and 
 to the Council of the district and S.A. where the factory or 
 workshop is situated on February 1st and August 1st every year. 
 
 Laundries are technically workshops, and as regards sanita- 
 tion, under the F. and W.A., 1907/ are subject to the same 
 
522 SANITARY LAW. 
 
 requirements as other workshops under the Act of 1901. This 
 includes all laundries used by way of trade or auxiliary to 
 charitable institutions. They are also open to Government 
 inspection. In addition to the sanitary requirements laid down 
 for factories and workshops, in factory laundries fans are required 
 for regulating the temperature of ironing rooms and for remov- 
 ing steam from wash-houses ; stoves for heating irons must be 
 separated from the ironing rooms, and gas-irons emitting noxious 
 fumes must not be used ; floors must be kept in good condition, 
 and so drained as to allow the water to flow off freely. 
 
 Among other provisions of the Factory Act, bearing upon 
 the well-being of the worker, may be mentioned those relating to 
 safety from machinery, accidents, age and sex of those employed, 
 and the hours and intervals for work and rest. Children under 
 1 2 years of age may not be employed in factories or workshops. 
 Above 12, they may be employed for half-time (if they have 
 attained a certain standard, and if the local educational bye-laws 
 permit), but must attend school for the other half. In factories 
 they must have a certificate of fitness (as to age and physique) 
 from the certifying surgeon, which may be coupled with conditions 
 as to the nature of the employment allowed. " Young persons " 
 are those between 14 and 18 (or between 13 and 14, subject to 
 conditions as to educational certificates), and are eligible for full- 
 time employment, with certain limitations. Certificates of fitness 
 are required for those under 16 employed in factories. A woman 
 must not be employed within four weeks after giving birth to a 
 child. 
 
 Offensive Trades. — The "offensive trades" are defined by 
 sec. 112, P.H.A. 1875, and sec. 51, P.H. (Amend.) Act, 1907, 
 as those of bloodboiler, bone-boiler, soapboiler, fellmonger, 
 tallow-melter, tripe-boiler, and any other trade, business, or 
 manufacture which the S.A. declare by Order confirmed by the 
 M.H., and published in such manner as the Board direct, to 
 be an offensive trade. 
 
 An urban S.A. may make bye-laws with respect to these 
 trades, when they^have been established with their consent, so 
 as to prevent or diminish any nuisance arising therefrom (sec. 
 113); but a rural authority would have to apply to the M.H. for 
 power, under sec. 276, to apply these provisions. 
 
 Model Bye-laws have been issued in regard to not only the 
 six trades mentioned in sec. 112 of the Act of 1875, Dut a ^ s0 m 
 reference to the trades of a leather-dresser, tanner, fat-melter or 
 fat-extractor, glue-maker, size-maker, blood-drier, and gut-scraper. 
 The same general provisions appear in all, with numerous 
 additions or variations as required by the conditions of the 
 
OFFENSIVE TRADES.. 523 
 
 particular trade in question. The following summary will show 
 their general scope and character : — 
 
 " (a) All materials not required for immediate use or treatment 
 shall be so stored as to prevent effluvium. (0) The best practi- 
 cable means must be adopted for rendering any offensive vapours 
 emitted during melting, boiling, etc., innocuous. The vapour 
 must be either discharged into the external air in such a manner 
 and at such a height as to admit of its diffusion without injurious 
 effects; or shall be passed directly from the pan, etc., through 
 a fire ; or into a condensing apparatus ; or through a condensing 
 apparatus and then through a fire ; in such a manner as effectually 
 to consume the vapour or deprive it of all noxious or injurious 
 properties, (c) The drainage on the premises must be kept in 
 efficient order. Bone-boilers must cool all hot liquid refuse 
 before passing it into any drain, (d) Floors must be kept in 
 good order so as to prevent the absorption of filth. In the 
 majority of these trades it is advisable to require the floors to 
 be either swept, washed, scraped, or otherwise cleansed at the 
 close of every working day. All refuse so collected, by scraping 
 or sweeping, shall be removed forthwith from the premises in 
 covered receptacles, unless intended to be forthwith subjected 
 to further trade processes on the premises, (e) Walls must be 
 kept in good order so as to prevent the absorption of filth, and, 
 if necessary, be scraped. Limewashing of walls and ceilings 
 twice a year is necessary in regard to these trades, (f) All 
 apparatus, including implements and vessels, must be kept clean ; 
 where possible, this should be done daily, (g) Waste lime result- 
 ing from the businesses of fellmongers and tanners must be 
 removed at once, and under close cover, (h) Tanks used by 
 fellmongers for washing or soaking skins must be emptied and 
 cleansed as often as may be necessary to prevent effluvia. 
 (i) Every facility must be allowed for the access to the premises 
 of the Medical Officer of Health, Inspector of Nuisances, 
 Surveyor, or any Committee appointed by the authority, for the 
 purpose of inspection at all reasonable times." 
 
 Section 114 enacts that, if the M.O.H., or two legally qualified 
 medical practitioners, or ten inhabitants of a district, certify that 
 any of the following places are a nuisance, or injurious to health, 
 it is the duty of the S.A. to take proceedings against the offender, 
 who is liable to a penalty not exceeding ^5, nor less than 40J., 
 unless he can show that he has used the best practical means 
 for abating such nuisance, or preventing or counteracting such 
 effluvia. The premises mentioned in this section are " any 
 candle-house, melting-house, melting-place, or soap-house, or 
 any slaughter-house, or any building or place for boiling offal 
 
524 SANITARY LAW. 
 
 or blood, or for boiling, burning, or crushing bones, or any 
 manufactory, building, or place used for any trade, business, 
 process, or manufacture causing effluvia." The same powers 
 are applicable where a nuisance, affecting the inhabitants of a 
 district, arises from offensive trades carried on in premises 
 situated beyond the limits of the district (sec. 115). 
 
 Rag Flock. — The Rag Flock Act, 191 1, prohibits any one 
 selling or having in his possession for sale any flock manufactured 
 from rags, or use for the making of any article of upholstery, 
 cushions, or bedding, any such flock unless it conforms to such 
 standard of cleanliness as may be prescribed by Regulation. The 
 existing Regulations, issued in 191 2, require that the amount of 
 soluble chlorine, as chlorides, removed by thorough washing with 
 distilled water at a temperature not exceeding 25 C, from not 
 less than 40 grammes of a well-mixed sample of flock shall not 
 exceed 30 parts of chlorine in 100,000 parts of the flock. 
 
 Slaughter-houses are defined by sec. 4, P.H.A., 1875, and 
 sec. 169 of the same Act empowers any urban S.A. to provide 
 abattoirs or slaughter-houses, and also license those belonging 
 to private owners. The S.A. must make bye-laws for the 
 licensing and inspection of slaughter-houses and knackers' yards, 
 preventing cruelty therein, keeping the same clean, for the daily 
 removal of filth, and for the proper supply of water. The 
 following model bye-laws are applicable to these requirements : — 
 
 " (a) Licences. — Applications for licence of existing premises, 
 or erection of new slaughter-houses, must be made upon a 
 specified form, and must include full particulars as to the 
 position, form, area, cubic space, etc., of the buildings and 
 appendages ; materials and construction of walls and floors ; 
 means of water-supply, drainage, lighting, and ventilation ; means 
 of access for cattle ; number, position, and size of stalls or lairs, 
 and number of animals to be accommodated therein, distinguish- 
 ing oxen, calves, sheep, and swine. The boundaries must also 
 be shown, and, in the case of old premises, particulars as to 
 the ownership and the applicant's tenure must be given. The 
 areas where the P.H. (Amend.) A., 1890, has been adopted the 
 licence shall run for one year only, or such period as the S.A. 
 shall specify in the licence. If the licensee is convicted under 
 sees. 1 1 6-1 1 9 of the P.H. A., 1875, a court of justice may revoke 
 the licence. 
 
 "(b) Registration. — If the Sanitary Authority approve the 
 application, a licence shall be issued to the applicant, and must 
 be registered by him at the office of the Sanitary Authority. 
 
 "(c) Inspection. — Free access to every slaughter-house for the 
 purpose of Inspection must be afforded at all reasonable times 
 
SLAUGHTER-HOUSES. 525 
 
 to the Medical Officer of Health, Inspector, Surveyor, and 
 Committees appointed by the Sanitary Authority. 
 
 " (d) Water must be supplied to every animal kept in a lair 
 prior to slaughter. 
 
 " (e) Mode of Slaughter. — Cattle must be secured by the head 
 so as to be felled with as little pain as practicable. 
 
 " (/) Drainage, water-supply , and ventilation must be kept in 
 efficient order. 
 
 " (g) Cleanliness. — The walls and floor must be kept in good 
 order and repair^ and must be thoroughly cleansed within three 
 hours after any slaughtering; the walls and ceiling must be 
 limewashed four times yearly, that is to say, within the first 
 ten days of March, June, September, and December respectively. 
 
 " (h) Afiimals not to be kept. — No dog may be kept in a 
 slaughter-house ; nor other animal, unless intended for slaughter 
 upon the premises, and then only in proper lairs, and not longer 
 than may be necessary for preparing it for slaughter by fasting or 
 otherwise. 
 
 " (i) Removal of Refuse. — Suitable vessels made of non- 
 absorbent materials, and provided with close-fitting covers, must be 
 provided for 'the reception of blood, manure, garbage, and other 
 refuse. All such matters must be placed in these vessels imme- 
 diately after the slaughtering. The refuse must be removed within 
 twenty-four hours, and the vessels forthwith cleansed. All skins, 
 fat, and offal must be removed within twenty-four hours." 
 
 Alkali and Chemical Works. — These are inspected and regu- 
 lated by the M.H., under the Alkali Works Act, 1906. The 
 following processes of manufacture come under this Act : — 
 
 " (1) Alkali works, that is to say, every work for {a) the manu- 
 facture of sulphate of soda or sulphate of potash, or (b) the treat- 
 ment of copper ores by common salt or other chlorides, whereby 
 any sulphate is formed, in which muriatic acid gas is evolved. 
 (2) Cement works. (3) Smelting works, that is to say, works in 
 which sulphide ores, including regulars, are calcined or smelted. 
 (4) Sulphuric acid works, that is to say, works in which the 
 manufacture of sulphuric acid is carried on by the lead chamber 
 process, namely, the process by which sulphurous acid is con- 
 verted into sulphuric acid by the agency of oxides of nitrogen and 
 by the use of a lead chamber. (5) Sulphuric acid works, that is 
 to say, works in which the manufacture of sulphuric acid is carried 
 on by any process other than the lead chamber process, and 
 works for the concentration or distillation of sulphuric acid. 
 (6) Chemical manure works, that is to say, works in which the 
 manufacture of chemical manure is carried on, and works in 
 which any mineral phosphate is subjected to treatment involv- 
 
526 SANITARY LAW. 
 
 ing chemical change through the application or use of any acid. 
 (7) Gas liquor works, that is to say, works (not being sulphate of 
 ammonia works or muriate of ammonia works) in which sulphu- 
 retted hydrogen or any other noxious or offensive gas is evolved 
 by the use of ammoniacal liquor in any manufacturing process, 
 and works in which any such liquor is desulphurised by the appli- 
 cation of heat in any process connected with the purification of 
 gas. (8) Nitric acid works, that is to say, works in which the 
 manufacture of nitric acid is carried on, and works in which nitric 
 acid is recovered from oxides of nitrogen. (9) Sulphate of 
 ammonia works and muriate of ammonia works, that is to say, 
 works in which the manufacture of sulphate of ammonia or of 
 muriate of ammonia is carried on. (10) Chlorine works, that is 
 to say, works in which chlorine is made or used in any manufac- 
 turing process, (n) Muriatic acid works, that is to say, (a) 
 Muriatic acid works, or works (not being alkali works as defined 
 in this Act) where muriatic acid gas is evolved either during the 
 preparation of liquid muriatic acid or for use in any manufacturing 
 process ; (b) tin-plate flux works, that is to say, works in which any 
 residue or flux from tin-plate works is calcined for the utilization 
 of such residue or flux, and in which muriatic acid gas is evolved ; 
 and (c) salt works, that is to say, works (not being works in which 
 salt is produced by refining rock salt, otherwise than by the disso- 
 lution of rock salt at the place of deposit) in which the extraction 
 of salt from brine is carried on, and in which muriatic acid gas is 
 evolved. (12) Sulphide works, that is to say, works in which 
 sulphuretted hydrogen is evolved by the decomposition of metallic 
 sulphides, or in which sulphuretted hydrogen is used in the pro- 
 duction of such sulphides. (13) Alkali waste works, that is to say, 
 works in which alkali waste or the drainage therefrom is subjected 
 to any chemical process for the recovery of sulphur or for the 
 utilisation of any constituent of such waste or drainage. (14) 
 Venetian red works, that is to say, works for the manufacture of 
 Venetian red, crocus, or polishing powder, by heating sulphate or 
 some other salt of iron. (15) Lead deposit works, that is to say, 
 works in which the sulphate of lead deposit from sulphuric acid 
 chambers is dried or smelted. (16) Arsenic works, that is to say, 
 works for the preparation of arsenious acid, or where nitric acid 
 or a nitrate is used in the manufacture of arsenic acid or an 
 arseniate. (17) Nitrate and chloride of iron works, that is to say, 
 works in which nitric acid or a nitrate is used in the manufacture 
 of nitrate or chloride of iron. (18) Bisulphide of carbon works, 
 that is to say, works for the manufacture of bisulphide of carbon. 
 (19) Sulpho-cyanide works, that is to say, works in which the 
 manufacture of any sulpho-cyanide is carried on by the reaction 
 
OFFENSIVE TRADES. 527 
 
 of bisulphide of carbon upon ammonia or any of its compounds. 
 (20) Picric acid works, that is to say, works in which nitric 
 acid or a nitrate is used in the manufacture of picric acid. (21) 
 Paraffin oil works, that is to say, works in which crude shale oil is 
 refined. (22) Bisulphite works, that is to say, works in which 
 sulphurous acid is used in the manufacture of acid sulphites of the 
 alkalis or alkaline earths. (23) Tar works, that is to say, works 
 where gas-tar or coal-tar is distilled or is heated in any manufac- 
 turing process. (24) Zinc works, that is to say, works in which, 
 by the application of heat, zinc is extracted from the ore, or from 
 any residue containing that metal." 
 
 The following are the requirements of the Act of 1906 with 
 respect to alkali works. Every such work must be carried on in 
 such a manner that 95 per cent, of the hydrochloric acid gas 
 evolved must be condensed, and not more than ^th of a grain of 
 hydrochloric acid gas per cubic foot of air, smoke or chimney 
 gases must escape from the works into the atmosphere. Nor 
 must there be more of the acid gases of sulphur and nitrogen 
 than the equivalent of 4 grains of sulphuric anhydride per cubic 
 foot of air. 
 
 Acid drainage must not be allowed to mix with alkali waste 
 so as to cause a nuisance. The owners of alkali works may 
 require the S.A. to provide and maintain, at his expense, a drain 
 for carrying the acid waste into the sea, or any watercourse into 
 which it can be taken without breach of the Rivers Pollution 
 Prevention Act, 1876. Alkali waste must not be deposited or 
 discharged without the best practicable and available means 
 being used to prevent nuisance. Similar regulations apply to 
 sulphuric acid works. The gases escaping into the atmosphere 
 must not have an acidity equivalent to more than 4 grains of 
 sulphuric anhydride per cubic foot. The other works scheduled 
 in the Acts must employ the best practicable means for preventing 
 the escape of noxious and offensive gases, and for rendering them 
 harmless and inoffensive, subject to the qualification in the case 
 of sulphuric acid works as to the degree of aerial vitiation by the 
 escaping gases. 
 
APPENDIX. 
 
 MEASURES OF LENGTH. 
 
 The Standard Metre is |^§§g of the distance, at the temperature of 16*3° C, 
 between the ends of a certain bar, called the " Toise of Peru," kept in the 
 French Archives, and is approximately the ten-millionth part of the distance 
 from one of the earth's poles to the Equator, at the meridian of Paris. This 
 measure, and those founded on it, is lawful in this country, and a copy 01 the 
 standard metre is kept in the Exchequer Office at Westminster. 
 
 The English Standard Yard is the distance, at the temperature of 62 F., 
 between two marks on a certain bar which is kept in the office of the 
 Exchequer. 
 
 The relative values of the Metric and English measures of length can be 
 gathered from the following table : — 
 
 
 Metres. 
 
 Inches. 
 
 Feet. 
 
 Yards. 
 
 Miles. 
 
 Kilometre 
 
 IOOO 
 
 
 
 
 0*6214 
 
 Hectometre . 
 
 IOO 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Decametre . 
 
 IO 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Metre 
 
 1 
 
 39 37 
 
 3 28 
 
 10936 
 
 — 
 
 Decimetre 
 
 O'l 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Centimetre . 
 
 O'OI 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Millimetre . 
 
 0*001 
 
 0-03937 
 
 — 
 
 •— * 
 
 "■■■ 
 
 MEASURES OF AREA. 
 
 Square Kilometre 
 
 Hectometre, or Hectare 
 Decametre, or Are 
 Metre .... 
 Decimetre. 
 Centimetre 
 Millimetre 
 
 Square metres. 
 
 I OOOOOO 
 
 I OOOO 
 
 IOO 
 
 1 
 
 O'OI 
 O'OOOI 
 O'OOOOOI 
 
 British measures of area. 
 0*3861 sq. mile. 
 
 2-4711 
 119*6 
 10-764 
 
 I5-5 
 
 0,I 55 
 0-00155 
 
 acres, 
 sq. yards 
 
 feet. 
 
 inches. 
 
 sq. 
 sq. 
 
 »» 
 
 SOLID MEASURES. 
 
 I Cubic Decametre, or Kilostere, equals 35,316*5 
 Metre, or Store, ,, 35*3 
 
 Decimetre, or Millistere, ,, 61*025 
 
 Centimetre ,, 0*061 
 
 Millimetre ., O'oooo6i 
 
 11 
 
 »> 
 
 cubic feet. 
 
 11 
 cubic inches. 
 
 11 
 ft 
 
53o 
 
 APPENDIX. 
 
 MEASURES OF WEIGHT. 
 
 The metric Standard Kilogramme is the weight, at the temperature of the 
 maximum density of water (4 C), and under the atmospheric pressure of 
 760 millimetres of mercury, in the latitude of Paris, of a certain piece of 
 platinum which is kept in the French Archives. A copy of this standard 
 kilogramme is kept in our Exchequer Office. The kilogramme was at first 
 intended to be the weight of one cubic decimetre of pure water at its maximum 
 density, but it is in actual fact slightly greater. 
 
 The English Standard Pound Avoirdupois is the weight, at the temperature 
 of 62 F., and under the atmospheric pressure of 30 inches of mercury, in the 
 latitude of London, and at or near the level of the sea, of a certain piece of 
 platinum, which is kept in the Exchequer Office at Westminster. 
 
 The relative values of the Metric and English weights is shown in the 
 following table : — 
 
 Kilogramme 
 
 Hectogramme 
 
 Decagramme 
 
 Gramme . 
 
 Decigramme 
 
 Centigramme 
 
 Milligramme 
 
 Grammes. 
 
 1000 
 
 IOO 
 
 10 
 
 I 
 
 O'l 
 
 O'OI 
 O'OOI 
 
 Grains. 
 
 15432 
 
 I5'432 
 0-0154 
 
 Avoir, ozs. 
 
 353 
 
 0-035: 
 
 Avoir, lbs. 
 
 2 2 
 
 - 0022 
 
 MEASURES OF CAPACITY. 
 
 The metric Standard Litre is the volume of a kilogramme of pure water 
 at its temperature of maximum density (4 C.) and under the atmospheric 
 pressure of 760 millimetres of mercury. It was originally intended to be a 
 cubic decimetre, but is actually a little greater. Under the above-mentioned 
 conditions, a litre of pure water weighs one kilogramme. 
 
 The English Standard Gallon is the volume of 10 lbs. avoirdupois of pure 
 water, at the temperature of 62 F., and under the atmospheric pressure of 
 30 inches of mercury. 
 
 The relative values of the Metric and English measures of capacity is 
 shown in the following table : — 
 
 Kilolitre . 
 Hectolitre 
 Decalitre 
 Litre . 
 Decilitre . 
 Centilitre 
 Millilitre . 
 
 Cubic 
 centimetres. 
 
 I 000000 
 
 I OOOOO 
 
 I OOOO 
 
 1000 
 
 100 
 
 10 
 
 1 
 
 Fluid ozs. 
 
 353 
 
 Pints. 
 
 1-76 
 
 Gallons. 
 
 22 
 
 Cubic ins. 
 
 61-027 
 
APPENDIX. 
 
 533 
 
 THE CHEMICAL SYMBOLS AND ATOMIC WEIGHTS OF 
 
 ELEMENTARY BODIES. 
 
 Names of 
 
 Chemical 
 
 Atomic 
 
 Names of 
 
 Chemical 
 
 Atomic 
 
 elements. 
 
 symbols. 
 
 weights. 
 
 elements. 
 
 symbols. 
 
 weights. 
 
 Aluminium . 
 
 Al 
 
 27'5 
 
 Nitrogen 
 
 N 
 
 I4*0 
 
 Antimony 
 
 Sb 
 
 I20'0 
 
 Oxygen 
 
 
 
 16*0 
 
 Arsenic . 
 
 As 
 
 75"o 
 
 Palladium . 
 
 Pd 
 
 IO57 
 
 Barium . 
 
 Ba 
 
 137-0 
 
 Phosphorus 
 
 P 
 
 3TO 
 
 Bromine . 
 
 Br 
 
 8o*o 
 
 Platinum 
 
 Pt 
 
 I97-2 
 
 Cadmium 
 
 Cd 
 
 II2T> 
 
 Potassium . 
 
 K 
 
 39'o 
 
 Calcium . 
 
 Ca 
 
 40*0 
 
 Rubidium . 
 
 Rb 
 
 853 
 
 Carbon . 
 
 C 
 
 I20 
 
 Selenium . 
 
 Se 
 
 788 
 
 Chlorine . 
 
 CI 
 
 355 
 
 Silicon . 
 
 Si 
 
 28-0 
 
 Chromium . 
 
 Cr 
 
 5 2 *5 
 
 Silver . 
 
 Ag 
 
 io8 # o 
 
 Cobalt . . 
 
 Co 
 
 59 "o 
 
 Sodium . 
 
 Na 
 
 23-0 
 
 Copper . 
 
 Cu 
 
 63-2 
 
 Strontium . 
 
 Sr 
 
 87-4 
 
 Fluorine . 
 
 F 
 
 19*0 
 
 Sulphur 
 
 S 
 
 320 
 
 Gold . . . 
 
 Au 
 
 196*2 
 
 Tantalum . 
 
 Ta 
 
 182*0 
 
 Hydrogen 
 
 H 
 
 i*o 
 
 Tellurium . 
 
 Te 
 
 125*0 
 
 Iodine 
 
 I 
 
 1266 
 
 Thallium 
 
 Tl 
 
 203-7 
 
 Iridium . 
 
 Ir 
 
 1927 
 
 Thorium 
 
 Th 
 
 2 3 i 's 
 
 Iron . 
 
 Fe 
 
 56-0 
 
 Tin . 
 
 Sn 
 
 118-0 
 
 Lead . 
 
 Pb 
 
 206 -5 
 
 Titanium 
 
 Ti 
 
 48-0 
 
 Lithium . 
 
 Li 
 
 7-0 
 
 Tungsten . 
 
 W 
 
 184-0 
 
 Magnesium . 
 
 Mg 
 
 24-0 
 
 Uranium 
 
 U 
 
 240*0 
 
 Manganese . 
 
 Mn 
 
 55'o 
 
 Vanadium . 
 
 V 
 
 5i*3 
 
 Mercury . 
 
 Hg 
 
 200'0 
 
 Yttrium . 
 
 Y 
 
 88 -o 
 
 Molybdenum 
 
 Mo 
 
 95'5 
 
 Zinc 
 
 Zn 
 
 65*0 
 
 Nickel . 
 
 Ni 
 
 59"o 
 
 Zirconium . 
 
 Zr 
 
 89-4 
 
 PREPARATION OF CULTURE MEDIA. 
 
 A variety of culture media have been alluded to in the text, particularly in 
 the section which deals with the bacteriological examination of a water sample. 
 The manner of preparing but one has been given in detail — namely, the bile- 
 salt glucose broth used in MacConkey's method. Details as to some other 
 media in common use are given below. 
 
 Nutrient Broth. — One pound of meat, free from fat, must be minced finely, 
 then infused in a litre of cold distilled water, and allowed to stand in a cold 
 place for twenty-four hours. The whole mass is then strained through a cloth, 
 and distilled water added to the filtrate so as to make up the volume of fluid 
 to one litre. Ten grammes of peptone and five grammes of common salt are 
 now added to the litre of fluid, which is then boiled in the steam sterilizer for 
 one hour at 100 C. Owing to the presence of acid phosphates of potassium 
 and sodium, weak acids of the glycolic series and organic compounds in which 
 the acid character predominates, this meat extract will be more or less acid. 
 It will always react acid to phenolphthalein, but occasionally reacts neutral or 
 even alkaline to litmus. Further, if exactly neutral to litmus, it will be found 
 to react acid to phenolphthalein. The main reason for this is due to the fact 
 that litmus is insensitive to many weak organic acids, the presence of which is 
 
534 APPENDIX. 
 
 readily indicated by phenolphthalein. Estimate the reaction of the medium by 
 
 placing 25 c.c. of it into a clean beaker, running in 0*5 c.c. of phenolphthalein 
 
 solution, immersing the beaker in a water-bath, and raising to the boil. Now 
 
 cautiously run in to the medium in the beaker, standing in the water-bath at 
 
 N 
 the boil, some — NaOH solution, until the end point is reached as indicated 
 10 
 
 by the development of a faint pink tinge. Note the amount of deci-normal soda 
 solution used. It is convenient to use broth media standardized to +10, the 
 symbol + meaning acid and — meaning alkaline, in both cases to phenolphtha- 
 lein as indicator. Briefly, the method of standardizing a litre of broth or other 
 medium to +10 consists in subtracting 10 from the initial titre of the medium 
 mass ; the remainder indicates the number of cubic centimetres of normal soda 
 solution that must be added to the medium, per litre, to render the reaction + 10. 
 
 N 
 Say, 25 c.c. of the medium have required the addition of 5*65 c.c. — NaOH 
 
 solution to neutralize it, and therefore 1000 c.c. will require 226 c.c. or 
 
 N ... 
 
 22'6 c.c. of — NaOH solution. The initial titre, then, of this medium will 
 
 be +22'6, and as such requires the addition of (22*6 — io)i2'6 c.c. of normal 
 NaOH per litre to leave its finished reaction at +10. To be strictly accurate, 
 allowance must be made for the volume of medium used in the titrations, and 
 remembrance made that the remainder of medium to be neutralized does not 
 now measure a full litre. Say, three titrations were made, each with 25 c.c, 
 then the original bulk of the medium will be but 925 c.c, requiring but 
 11*65 c - c - of normal NaOH to make it +10. 
 
 Having brought the medium to the required reaction, heat again for half 
 an hour at ioo° C, to complete the precipitation of phosphates. Filter 
 through Swedish filter-paper into sterile tubes (10 c.c. in each). Plug the 
 tubes with cotton wool, and then sterilize these in the steamer on three suc- 
 cessive days for twenty minutes. 
 
 Glucose and Lactose Broth. — These are simply the above ordinary broths 
 containing 1 or 2 per cent, of either grape or milk sugar. The steps in the 
 preparation are the same as those just described. 
 
 Nutrient Gelatine. — This is made by adding 10 to 15 per cent, of best 
 gold-label gelatine, cut into small pieces, to ordinary broth prepared as above, 
 and then melting it by steaming at ioo° C. for one hour. Estimate the 
 reaction of the medium mass, as explained for broth, then add sufficient normal 
 soda solution to render the reaction of the calculated bulk of medium +10. 
 Replace in the steamer, and keep at ioo° C. for twenty minutes, to precipitate 
 all the phosphates. Allow to cool to 6o° C. Add the whites of two eggs for 
 each litre of medium, replace in steamer at ioo° C. for half an hour ; then 
 filter through Chardin paper into sterile tubes. Sterilize these at ioo° C. 
 for twenty minutes on each of three consecutive days. 
 
 Glucose and Lactose Gelatine are made in the same way, adding 1 to 2 
 per cent, of the respective sugars. 
 
 Nutrient Agar-Agar. — Add 15 grms. of agar, cut into very fine fragments, 
 to a litre of ordinary broth, prepared as explained. Dissolve by heating at 
 ioo° C. for an hour and a half. Estimate the reaction of the medium mass as 
 explained under the head of " Broth ; " then add sufficient normal soda solution 
 to render the reaction of the calculated bulk of the medium -f- 10. Replace 
 in the steamer for twenty minutes to complete the precipitation of phosphates. 
 Allow the medium to cool to 6o° C, add whites of two eggs, replace in 
 steamer, and keep at ioo° C. for half an hour. Now filter through Chardin 
 paper, by the aid of a hot-water funnel, into sterile tubes. Sterilize these in 
 the steamer at ioo° C. for half an hour on each of three successive days. 
 
APPENDIX. 535 
 
 Glycerine Agar is made in the same way, 6 per cent, of glycerine being 
 added after filtration. 
 
 Glucose and Lactose Agar are made as under ordinary agar, 2 per cent, 
 of the respective sugars being added, as the case may be. If required to be 
 tinted with neutral red, 2 per cent, of a half per cent, solution of neutral red 
 is added before filtration. 
 
 Peptone Solution.— One to 2 per cent, of Witte's peptone with 0*5 per cent, 
 of common salt are dissolved in distilled water by heating. The fluid is then 
 filtered, placed in tubes, and sterilized. In this medium, cholera vibrios grow 
 with great rapidity. It is also much used for testing the formation of indol 
 by different bacteria. 
 
 Glucose Peptone Solution. — Made by dissolving, by means of heat, I grm. 
 of glucose, I grm. of peptone, and £ grm. of salt in 100 c.c. of distilled 
 water. This is filtered, rendered neutral to litmus, placed in steamer at 
 ioo° C. for half an hour, then tubed into test-tubes containing inverted fer- 
 mentation tubes, and sterilized for twenty minutes at ioo° C. on three suc- 
 cessive clays. 
 
 Lactose Peptone Solution. —Prepared as the foregoing, substituting lactose 
 for the glucose. 
 
 Sucrose Peptone Solution.— Prepared as the foregoing, substituting pure 
 cane-sugar for the glucose or lactose. 
 
 Mannite Peptone Solution. — Prepared as the foregoing, substituting the 
 alcohol mannite for one or other of the sugars. 
 
 Proskauer and Capaldi's Media. — The No. I. medium has the following 
 composition : Asparagin and mannke of each o'2 per cent. ; potassium mono- 
 phosphate, o*2 per cent. ; sodium chloride and calcium chloride of each o"02 
 per cent. ; and of magnesium sulphate, 001 per cent. The reagents are dis- 
 solved in distilled water, sterilized for an hour at ioo° C. The medium is 
 then rendered neutral to litmus by the addition of sufficient normal caustic 
 soda solution. Sufficient litmus solution is added to give the medium a purple 
 tint. It is now tubed and sterilized in the usual way for twenty minutes at 
 ioo° C. on three successive days. 
 
 The No. II. medium contains 2 per cent, of Witte's peptone and o*i per 
 cent, of mannite dissolved in distilled water. Sterilized at 100 C. for an hour. 
 This will be now found to be alkaline ; it is next carefully rendered neutral 
 to litmus by the addition of a saturated solution of citric acid. Litmus solu- 
 tion is added to give it a deep red colour. It is now tubed and sterilized in 
 the usual way for twenty minutes at ioo° C. on three successive days. These 
 media are of great value in the differential diagnosis between the B. coli and 
 the B. typhosus. 
 
 Milk. — Fresh milk and free from any preservative is steamed for half an 
 hour at 100 C, and then placed in a cool place overnight for separation of 
 cream. The milk is then siphoned off from beneath the cream, and placed in 
 sterile tubes j if necessary, sufficient litmus solution is added to give it a purple 
 tinge. The tubes are plugged, and then sterilized at ioo° C. for twenty 
 minutes on each of three successive days. 
 
 Potato Medium. — A large potato is well washed and scrubbed with a 
 brush. A cylinder is then bored from its interior, and cut obliquely. The 
 peel from the ends is cut off, and the wedges so obtained allowed to soak 
 overnight in cold water to get rid of any excess of starch. Each wedge of 
 potato is then placed in a test-tube, previously fitted with a pad of cotton 
 wool at the bottom, and filled for about \ inch in depth with distilled water. 
 The tube is now plugged with cotton wool, and sterilized at ioo° C. for 
 twenty minutes on three successive days. 
 
INDEX 
 
 ABS 
 
 bsorption of heat by cloth- 
 ing, 294 
 
 by soil, 210 
 
 carus domesticus, 173 
 — farinoe, 175 
 — scabiei, 369 
 :cessory foods, 186 
 cetylene, 26 
 
 chorion Schenleinii, 365 
 ;id, boric, in milk, 170 
 — , carbonic, 4 
 cidity of beer, 199 
 
 • of bread, 176 
 ■ of vinegar, 187 
 
 • of wice, 205 
 cids, vegetable, 134 
 
 ctual increase of population, 
 
 418 
 
 dulteration of food, law as 
 
 to, 486 _ 
 
 ge distribution of population , 
 
 419 
 
 ir, amount needed for 
 
 animals, 28 
 
 for lights, 23 
 
 for man, 25 
 
 — , effects of varying pres- 
 sure, 407 
 
 — , examination of, 48 
 — , impurities of, 11 
 — , movements of, 9, 35 
 
 — of sewers, 17 
 lbumin, 130 
 
 lcohol, nutritive value of 
 
 z 94 . . 
 
 — , determination of, 199 
 
 les, 196 
 
 lkali works, fumes from, 18 
 
 T'. law as to ' 5 2 5 
 
 .mmonia in water, 91 
 
 .mceba of dysentery, 366 
 
 .nalysis of air, 52 
 
 - of milk, 166 
 
 — of water, 79 
 nchylostoma, 373 
 nemometers, 398 
 neroid barometer, 405 
 oiimal, amount of air for, 28 
 
 -, of water for, 57 
 
 mthrax, 318 
 inticyclone, 412 
 mtiscorbutics, 153 
 
 BOO 
 
 Antiseptics, 353 
 
 Apparatus for water analysis, 
 
 84 
 Arithmetic mean, 441 
 Arrowroot, 181 
 Artesian well, 63 
 Artificial lighting, 19 
 
 ventilation, 41 
 
 Artisan dwellings, 233 
 Ascaris lumbricoides, 375 
 Ashpits, 466 
 
 , law relating to, 466 
 
 Aspects of houses, 215' 
 Asses' milk, 162 
 Atmospheric pressure, 6, 401 
 Atomic weights, 533 
 Averages, 441 
 
 Bacilli, 308 
 Bacillus coii, 116 
 
 typhosus, 118 
 
 Back-to-back houses, 216 
 Bacteria in air, 55 
 
 in water, 106 
 
 Bain-marie, use of, 164 
 Bakehouses, 480 
 Ball-traps, 255 
 Barley, 177 
 Barometers, 401 
 Barometric gradients, 409 
 Barracks, cubic space in, 30 
 Baths, 232, 287 
 Beans, 180 
 
 Bedding, disinfection of, 355 
 Beef tea, 154 
 Beer, 196 
 Bell-traps, 262 
 Berber system, 271 
 Bile-salt broth, no 
 Bilharzia ha>matobia, 376 
 Biological treatment of sew- 
 age, 270 
 Biith-rates, 420 
 , as affecting death-rates, 
 
 429. 
 Biscuits, 177 
 Boiling, as means of cooking, 
 
 J 47 
 , as means of disinfection, 
 
 354 
 Boots, 295 
 
 CHE 
 
 Boric acid in milk, 168 
 
 Bothriocephalus latus, 377 
 
 Brandy, 206 
 
 Bread, 175 
 
 Brewing, 197 
 
 B iicks, 218 
 
 Broth, 533 
 
 Bugs, 370 
 
 Buildings, definition of, 447 
 
 Burners for gas, 23 
 
 Butter, 171 
 
 Buys Ballot's law, 409 
 
 Byelaws, 450 
 
 Cabbage, 138 
 
 Caffein, 190 
 
 Calandra granaria, 175 
 
 Calcium salts in water, 73 
 
 Calculation of cubic space, 
 
 49 
 
 • of diets, 140 
 
 Calorie, 136 
 Camps, 279 
 Canal boats, 505 
 
 definition of, 443 
 
 Candle standard, 19 
 Cane sugar, 132 
 Carbohydrates, 132 
 Carbolic acid, 350 
 Carbon dioxide, 12 
 
 ■ , amount exhaled, 27 
 
 , estimation of, 51 
 
 , monoxide, 13 
 
 Carburetted hydrogen, 15 
 Carcel burner, 20 
 Casein, 165 
 
 Cattle, diseases of, 160 
 Causes of death, 430 
 Cellar dwellings, 509 
 Cement works, 512 
 Census, importance of, 408 
 Cerebro-spinal fever, 320 
 Cesspools, law as to, 466 
 Chalk, water from, 71 
 Cheese, 172 
 Chemical analysis of air, 52 
 
 of water, 84 
 
 purification of sewage, 
 
 274 
 
 of water, 82 
 
 weights and symbols, 519 
 
53§ 
 
 CHE 
 
 Chemical woiks, law relating 
 
 tp, 525 
 Chicken-pox, 319 
 Chicory, 193 
 Chigoe, 362 
 Child-welfare, 299 
 Chlorine as disinfectant, 349 
 
 in water, 90 
 
 Chocolate, 191 
 
 Cholera, 320 
 
 microbe, detection 
 
 123 
 Cisterns, 66 
 
 Claviceps purpurea, 180 
 Clay soils, 217 
 Cleansing, law as to, 456 
 Climate, 379 
 Closets, dry, 236 
 
 of, 
 
 water, 227 
 
 Closure of unfit houses, 467 
 Clothing. 288 _ 
 
 , disinfection of, 357 
 
 Clouds, 392 
 Coal gas, 22 
 Coccidium hominis, 368 
 Cocoa, 191 
 Coffee, 190 
 Collection of water, 65 
 
 samples, 80 
 
 Colon bacillus, 119 
 Cols, 413 
 
 Comma bacillus, 123 
 Common lodging houses, 510 
 Comparative mortality, 432 
 Compulsory detention in hos- 
 pital, 483 
 
 disinfection, 482 
 
 notification of disease. 
 
 Condensed milk, 171 
 Condensing stoves, 46 
 Constant water supply, 67 
 Contagion, 304 
 Contagious diseases, law as 
 
 to, 493 
 
 Cooking, 147 
 
 Copper as purifier of water, 
 82 
 
 Cornflour, 182 
 
 Coronse, 392 
 
 Corrected death-rates, 423 
 
 Corrosive sublimate as a dis- 
 infectant, 350 
 
 Cotton, 291 
 
 Cubic space, 29 
 
 , measurement of, 
 
 5° 
 Culture media, preparation 
 
 of, 533 
 Cyclones, 409 
 Cyllin, 358 , 
 Cysticerci, 159 
 
 Dairies, regulations for, 480 
 Damp-proof course, 217 
 Death, causes of, 430 
 Death-rates, 422 
 Deficiency of food, 153 
 
 INDEX 
 
 FIL 
 
 Definitions, sanitary, 446 
 Dew-point, 394 
 Dextrose, 137 
 Diarrhoea, epidemic, 319 
 
 , in relation to water, 73 
 
 Diets, 140 
 
 Dibdin slate-beds, 273 
 Diffusion of air, 10 
 Digestibility of food, 147 
 Diphtheria, 323 
 Diseases due to food, 152 
 
 ■ , infectious, 307 
 
 , notification of, 501 
 
 , zymotic, 430 
 
 Disinfectants, 358 
 
 , standardization of, 362 
 
 Disinfection, 353 
 
 , law, relating to, 482 
 
 Drainage of houses, 252 
 Drains, byelaws as to, 464 
 
 , definition of, 447 
 
 , examination of, 256 
 
 , law relating to, 463 
 
 , ventilation of, 259 
 
 Dry heat, disinfection by, 349 
 Dryness of wines, 204 
 Dustbins, 466 
 
 Dwellings, construction of, 
 214 
 
 , drainage of, 252 
 
 Dysentery, 325 
 
 Earth-closets, 236 
 Echinococcus disease, 161 
 Eggs, 161 
 
 Elements, chemical, 533 
 Encephalitis, 329 
 Energy from food, 140 
 Enteric fever, 325 
 Entozoa in water, 74 
 Epidemic diarrhoea, 321 
 Ergot in flour, 180 
 Error, probable, 442 
 Erysipelas, 330 
 Excess of food, 156 
 Excreta, composition of, 257 
 
 , disposal of, 246 
 
 Exercise, 295 
 Expectation of life, 427 
 Expired air, 13 
 Extraction, ventilation by, 41 
 Extracts of meat, 187 
 
 Factories, law as to, 514 
 
 , ventilation of, 41 
 
 Fans, ventilation by, 41 
 Fats, 131 
 
 Favus, parasite of, 357 
 Feathers, 290 
 Fever, enteric, 322 
 famine, 332 
 
 , relapsing, 332 
 
 , scarlet, 332 
 
 , typhus, 341 
 
 , yellow, 341 
 
 Fiducial point, 394 
 Filaria, 373 
 
 ' 
 
 HOU 
 
 Filter bed, 75 
 Filters, domestic, 77 
 Filtration of sewage, 279 
 
 of water, 75 
 
 Fish, 160 
 Flax. 292 
 Fleas as carriers of disease; 
 
 37o 
 Floor space in dwellings, 32 
 
 in hospitals, 250 
 
 in schools, 247 
 
 Floors, 222 
 Flour, 174 
 Food, 129 
 
 , amount required, 140 
 
 , cooking of, 147 
 
 , law relating to, 486 
 
 , nutritive value of, 136 \ 
 
 , unsound, law as to, 47H 
 
 Foot-and-mouth disease, 160 
 Forecasting of weather, 400 
 Formaldehyde, 359 
 
 in milk, 168 
 
 Fumigation, 358 
 Furs, 289 
 
 Gas burners, 22 
 
 , composition of, 21 
 
 , impurities from, 22 
 
 , stoves, 45 
 
 Gelatin, 134 
 
 Geological origin of soils, 211 
 
 Geometric mean, 442 
 
 Gin, 207 
 
 Glaisher's factors, 395 
 
 Glanders, 157 
 
 Glucose, 133 
 
 Gluton, 130 
 
 Glycerine in milk, 170 
 
 Goat's milk, 165 
 
 Goitre, 73 
 
 Golgi, cycle of, 333 
 
 Grape sugar, 136 
 
 Grates, sanitary aspects of, 4 
 
 Ground air, 213 
 
 water, 212 
 
 Guinea-worm, 372 
 Gully traps, 255 
 
 Habits, 289 
 
 Halos, 392 
 
 Hardness of water, 73 
 
 Heat, disinfection by, 347 
 
 Heat, purification of water by 
 
 78 , 
 
 , units of, 136 
 
 Heating of houses, 42 
 
 Htights, measurement of, 4c 
 
 Hemp, 293 
 
 Hesse's process, 53 
 
 Horses, flesh of, 479 
 
 Hospitals, 242 
 
 Hot air, disinfection by, 349 
 
 , heating by, 47 
 
 Hot-water appaatus, 224 
 House, construction of, 220 1 
 , law as to drainage of 
 
 461 
 
HOU 
 
 louses of Commons, ventila- 
 tion of, 40 
 
 lousing of the working 
 classes, 512 
 
 lovis bread, 176 
 
 rumidity of air, 391 
 
 lydraulic mean depth, 261 
 
 lygrometers, 392 
 
 lluminants, artificial, 21 
 mmunity, 310 
 mpurities of air, n 
 
 - of water, 72 
 ncubation of disease, 309 
 ndex error, 403 
 ndiarubber, 293 
 nfunt mortality, 427 
 nfection, 307 
 nfectious diseases, 315 
 , hospitals for, 252, 
 
 483 
 
 , law relating to, 493 
 
 , notification of, 501 
 
 nfluenza, 331 
 
 nlets for air, 37 
 
 noculation proiective, 314 
 
 nsects as parasites, 362 
 
 ntermittent filtration of sew- 
 age, 269 
 
 water supply, 66 
 
 nterpretation of analysis, 125 
 
 ron in water, 104 
 
 rrigation of sewage, 276 
 
 sobars, 408 
 
 solation of sick, 351 
 
 tch insect, 369 
 
 zal, 358 
 
 UTE, 293 
 
 Cefir, 163 
 •Coumiss, 163 
 
 ACTOSE, 167 
 
 atrines, 235 
 -.aw of error, 442 
 
 , sanitary, 444 
 
 -,ead, action of water on, 67 
 
 , estimation of, 103 
 
 Leishmania, 367 
 l,emon-juice, 183 
 jevulose, 133 
 -iernur system, 271 
 _,ife, expectation of, 439 
 
 , mean duration of, 434 
 
 — — tables, 435 
 
 -lights, artificial, 21 
 
 Lime, purification of sewage, 
 
 274 
 
 in water, 71 
 
 ^inen, 292 
 
 Macaroni, 177 
 VJacConkey's medium, no 
 
 INDEX 
 
 OUT 
 
 Made soils, 211 
 Magnesia in water, 71 
 Maize, 179 
 Malaria, 332 
 Maltose, 136 
 Manholes, 258 
 Margarine, 174, 490 
 
 , law as to, 492 
 
 Marriage rates, 414 
 
 Marsh air, 17 
 
 Mean age at death, 427 
 
 Means, 441 
 
 Measles, 338 
 
 Meat, 154 
 
 Mechanical ventilation, 41 
 
 Media, preparation of culture, 
 
 532 
 Mediterranean fever, 339 
 Mercuric chloride, 357 
 Meteorology, 379 
 Metrical system, 530 
 Microbes, 308 
 
 in air, 55 
 
 in sewer air, 17, 269 
 
 in water, 112 
 
 Microsporon furfur, 365 
 Middens, 235 
 Milk, 162 
 
 , adulteration of, 165 
 
 , law relating to, 480' 
 
 — — , preservation of, 168 
 Mineral salts in food, 138 
 Miners, mortality of, 432 
 Moisture in air, 383 
 Mortality and age, 423 
 
 and occupation, 431 
 
 and sex, 423 
 
 Mosquitoes, 336 
 Mumps, 338 
 Mussels, 163 
 
 Natural increase of popula- 
 tion, 410 
 
 ventilation, 31 
 
 Nessler's test, 82, 92 
 Neutral point, 401 
 Nitrates in water, 96 
 Nitrification of sewage, 273 
 Nitrites in water, 97 
 Nitrogen in air, 2 
 
 in food, 144 
 
 Notification of infection, 351 
 Nuisances, definition of, 472 
 , law as to, 472 
 
 Oatmeal, 179 
 
 Oats, 178 
 
 Occupation and mortality, 431 
 
 Offensive trades, law as to, 
 
 522 
 Oidium albicans, 365 
 Oil as illuminant, 24 
 Ovchocenciasis, 160 
 Organisms in air, 55 
 
 in water, 115 
 
 Oswego, 182 
 Outlets for air, 39 
 
 539 
 
 SAL 
 
 Overcrowding, 473 
 Owner, definition of, 447 
 Oxidizable matter in water, 98 
 Oxygen in air, 3 
 
 absorbed by water, 98 
 
 dissolved in water, 101 
 
 Ozone, 3 
 
 Pail-closets, 236 
 
 Parasites, 364 
 
 Paratyphoid bacilli, 120 
 
 Parish Councils, 453 
 
 Peas, 180 
 
 Pediculi, 369 
 
 Personal hygiene, 284 
 
 Phagocytosis, 311 
 
 Pipes for water, 66 
 
 Piroplasma, 368 
 
 Plague, 339 
 
 Plasmodium of malaria, 368 
 
 Poliomyelitis, 329 
 
 Population, 416 
 
 Porter-Clark process, 75 
 
 Potato, 181 
 
 Potters, mortality of, 433 
 
 Precipitation of sewage, 267 
 
 Preservation of food, 184 
 
 Privies, 235 
 
 Probable duration of life, 434 
 
 Proof spirit, 194 
 
 Protective inoculation, 311 
 
 Proteins, 130 
 
 Purification of sewage, 266 
 
 of water, 72 
 
 Quadratic mean, 442 
 Quantity of air required, 27 
 
 of food required, 141 
 
 of water required, 57 
 
 Rabies, 340 
 Radiation of heat, 44 
 Rain, 380 
 
 Rainfall in England and 
 Wales, 60 
 
 Scotland, 61 
 
 Ireland, 61 
 
 Rain-gauge, 389 
 Rectified spirit, 194 
 Refuse destructors, 248 
 , law as to, removal of, 
 
 449 
 Registration of births, 413 
 
 of deaths, 415 
 
 Relapsing fever, 341 
 
 Respiration, effect on air, 18 
 
 Rice, 179 
 
 Ringworm, 364 
 
 Rivers, prevention of pollution 
 
 of, 470 
 
 as sources of water, 61 
 
 Roofs, 220 
 Rum, 206 
 
 Rye, 178 
 
 Sago, 183 
 
 Salicylic acid in milk : 168 
 
540 
 
 INDEX 
 
 SAM 
 
 Samples, collection of air, 52 
 
 of water, 107 
 
 Sand filters, 75 
 Sanitary areas, 445 
 
 definitions, 446 
 
 law, 444 
 
 Scabies, 369 
 Scarlet fever, 341 
 Schools, 238, 303 
 School-hygiene, 299 
 Scurvy, 157 
 
 Seasonableness of fish, 163 
 Selection of sites, 215 
 Septic tanks, 272 
 Service pipes, 65 
 Sewage, composition of, 249 
 
 , disposal of, 265 
 
 , purification of, 266 
 
 Sewers, air in, 262 
 
 — — , construction of, 257 
 
 — — , definition of, 447 
 
 , law relating to, 458 
 
 , ventilation of, 263 
 
 Sex, distribution of, 419 
 
 ■ , influence on mortality, 
 
 423 
 
 Shell-fish, 163, 480 
 
 Ships, disinfection of, 489 
 
 Shoes, 300 
 
 Shone's ejectors, 265 
 
 Silk, 290 
 
 Simple continued fever, 342 
 
 Siphons, 254 
 
 Sites, 2 to 
 
 Slaughter-houses, 524 
 
 Sleep, 285 
 
 Slop-closets, 233 
 
 Sludge activated, 275 
 
 Small-pox, 342 
 
 and vaccination, 343 
 
 Smoke as a nuisance, 466 
 
 Soap, 286 
 
 Soft water, 73 
 
 Soils, 207 
 
 Soil-pipes, 251 
 
 Solutions, standard, 87 
 
 Soup, 151 
 
 Sources of water, 58 
 
 Spirilla, 304 
 
 Spirits, 206 
 
 Spirochaetes, 367 
 
 Springs, 61 
 
 Standard solutions, 85 
 
 Standards of air purity, 29 
 
 of water, 131 
 
 Standardization of disinfect- 
 ants, 362 
 
 Starches, 178 
 
 VEL 
 
 Statistics vital, 415 
 Steam, disinfection by, 354 
 Storage of water, 63 
 Stoves, 44 
 
 Streptococci in water, 122 
 Subsoil water, 212 
 Sugar, 136 
 
 in wines, 206 
 
 Sulphur dioxide, 361 
 Sulphuretted hydrogen, 15 
 Superheated steam, 355 
 Suspended matter in air, 54 
 
 in water, 105 
 
 Synoptic charts, 408 
 
 Tapeworms, 376 
 
 Tapioca, 182 
 
 Tartaric acid, 134 
 
 Tea, 187 
 
 Temperature, 381 
 
 Tents, law as to residents in, 
 
 507 
 Tetanus, 347 
 Theine, 188 
 Thermometers, 381 
 Thread-worms, 375 
 Thresh's disinfector, 357 
 Ticks, 370 
 Tidy's process, 98 
 Tinned foods, 185 
 Total solids in water, 89 
 Towns, death-rate of chief, 418 
 Traps, 253 
 Trichinosis, 374 
 Trough closets, 235 
 Trypanosomes, 366 
 Tub closets, 236 
 Tube wells, 63 
 Tuberculosis, 347 
 
 and animals, 161 
 
 ■ and milk, 338 
 
 Typhoid fever, 325 
 Typhus fever, 350 
 
 Unit of work, 137 
 
 Unsound food, law as to, 477 
 
 Vaccination, 315, 343 
 Valve closets, 228 
 Vans, law as to livers in, 507 
 Vapour, tension of, 388 
 Vegetable acids, 134 
 
 foods, 175 
 
 Velocity of air currents, 36 
 
 of w.nd, 390 
 
 ZYM 
 
 Venereal diseases, 499 
 Ventilation, artificial, 39 
 
 , natural, 31 
 
 of sewers, 263 
 
 Vermicelli, 177 
 Vernier of barometer, 403 
 Vibrio of cholera, 123 
 Vinegar, 187 
 Vital statistics, 415 
 Vitamines, 135 
 
 Walls, construction of, 219 
 Warming methods, 42 
 Wash-down closet, 229 
 Wash-out closet, 229 
 Waste-pipes, 263 
 Water, 55 
 Water-gas, 26 
 Water, action on lead, 67 
 
 , amount required, 56 
 
 , analysis of, 79 
 
 , bacteriology of, 106 
 
 ■ , classification of, 69 
 
 closets, 227 
 
 -, law relating to, 467 
 
 , collection of samples, 
 
 80, 107 
 
 , effects of impure, 70 
 
 , nitration of, 76 
 
 , impurities in, 69 
 
 , purification of, 72 
 
 , supply of hot, 224 
 
 in relation to cholera,! 
 
 321 
 
 to enteric fever, 326] 
 
 Weather, 379 
 
 Weight of air, 6 
 
 Wells, 61 
 
 Wheat, 174 
 
 Whisky, 206 
 
 Whooping cough, 338 
 
 Wind, 389 
 
 Wine, 200 
 
 Wool, 289 
 
 Woolsorters' disease, 316 
 
 Work, calculation of, 298 
 
 , standard of a clay's, 14;. 
 
 Yeast extracts, 187 
 Yellow fever, 350 
 
 Zymotic death-rate, 431 
 diseases, 309 
 
 PRINTED IN GREAT BRITAIN EY WILLIAM CLOWES AND SONS, LIMITED, BECCLES. 
 

 
 JBBAJtt 
 
 U.C. BERKELEY LIBRARIES 
 
 CDETEfiEMMl