LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Class 
 
EXAMINATION OF WATER. 
 
 LEFf MANN. 
 
BY THE SAME AUTHOR. 
 
 Sanitary Relations of the Coal-tar Colors. 
 
 BY THEODORE WEYL. 
 
 AUTHORIZED TRANSLATION. 
 
 I2mo. 154 pages. $1.25. 
 
 Handbook of Structural Formulae. 
 
 Containing 180 Structural Formula? (with alternate pages blank). 
 
 i2mo. $1.00. 
 
 Analysis of Milk and Milk Products. 
 
 Second Edition, Revised and Enlarged. 
 i2mo. Illustrated. 120 pages. $1.25. 
 
 Select Methods in Food Analysis. 
 
 BY HENRY LEFFMANN AND WILLIAM BEAM. 
 8vo. 374 pages. $2.50. 
 
EXAMINATION OF WATER 
 
 FOR 
 
 SANITARY AND TECHNIC PURPOSES, 
 
 BY 
 
 HENRY LEFFMANN, A.M., M.D., PH.D., 
 
 PROFESSOR OF CHEMISTRY IN THE WOMAN'S MEDICAL COLLEGE OF PENNSYL- 
 VANIA AND IN THE WAGNER FREE INSTITUTE OF SCIENCE; PRESIDENT 
 OF THE ENGINEERS' CLUB OF PHILADELPHIA 1901 ; VICE- 
 PRESIDENT (BRITISH) SOCIETY OF PUBLIC ANALYSTS 
 1901-02 ; CHEMIST STATE BOARD OF HEALTH 
 OF PA. (EASTERN DISTRICT.) 
 
 FIFTH EDITION, REVISED AND ENLARGED, WITH 
 ILLUSTRA TIONS. 
 
 OF THE 
 
 DIVERSITY } 
 
 OF 
 
 PHILADELPHIA 
 P. BLAKISTON'S SON & CO. 
 
 1012 WALNUT STREET 
 1904 
 
COPYRIGHT, 1903, BY P. BLAKISTON'S SON & Co. 
 
 PRESS OF 
 
 WM. F. FELL COMPi 
 PHILADELPHIA 
 
I DEDICATE THIS BOOK TO THE 
 MEMORY OF 
 
 /ID$ fl&otber, 
 
 TO WHOSE WISE PRECEPT AND EXAMPLE 
 
 / 
 IN MY BABYHOOD 
 
 I OWE WHATEVER MERIT MY MANHOOD YEARS 
 MAY SHOW. 
 
 1 63458 
 
If thou couldst, doctor, cast 
 The water of my land. 
 
PREFACE. 
 
 IrTthe present edition, numerous revisions have been 
 made but the plan of the book has not been disturbed. In 
 the four editions which have been issued, it has seen notable 
 changes in the attitude of experts toward certain methods. 
 When the first edition was issued, under the joint author- 
 ship of Dr. William Beam and myself, bacteriologists were 
 enthusiastically claiming to be able to determine absolutely 
 the presence or absence of disease-producing microbes in 
 water, and asserting that sanitary analysis of water by chem- 
 ical methods was about to become a matter of history. At 
 present, the limitations of bacteriology are evident, and the 
 value of routine chemical analysis is generally recognized. 
 Upon this point, and also on the question of the inherent 
 danger of unfiltered surface water even when not receiving 
 sewage directly, the book took decided stand, and the devel- 
 opment of the views of experts has fully justified it. Long 
 experience has convinced me that for determining the pota- 
 bility of water, the determinations of chlorin, nitrates and 
 nitrites afford the most satisfactory indications, and that the 
 
X PREFACE. 
 
 figures for nitrogen or ammonium (so-called "free am- 
 monia") and nitrogen by permanganate (so-called "albu- 
 minoid ammonia") are of much less value than is generally 
 supposed. The suggestion of Woodman, that phosphates 
 afford a useful datum, is worthy of special attention. 
 
 ng South Fourth Street, 
 
 Philadelphia, November, 1903. 
 
CONTENTS. 
 
 NOTE ON WATER-SUPPLY, 
 
 NATURAL HISTORY AND CLASSIFICATION OF NATURAL WATERS. 
 Rain Water Surface Water Subsoil Water 
 
 Deep Water, _______________________________ 16-21 
 
 ANALYTIC OPERATIONS. 
 
 Sanitary Examinations: 
 
 Collection and Preliminary Examination Total 
 Solids Chlorin Nitrogen in Ammonium Com- 
 pounds and Organic Matter Nitrogen as Ni- 
 trates Nitrogen as Nitrites Oxygen-consuming 
 Power Phosphates Dissolved Oxygen Pois- 
 onous Metals Biologic Examinations, _________ 22-87 
 
 Technic Examinations: 
 
 General Quantitative Analysis Spectroscopic An- 
 
 alysis Specific Gravity, _____________________ 87-105 
 
 INTERPRETATION OF RESULTS. 
 
 Statement of Analysis Sanitary Applications 
 Action of Water on Lead Technic Applica- 
 tions Boiler Waters Sewage Effluents Puri- 
 fication of Water Identification of Source of 
 Water, ____________________________________ 106-135 
 
 ANALYTIC DATA. 
 
 Factors for Calculation Conversion Table, ------- 136-137 
 
 INDEX. 
 
 XI 
 
OF THE 
 
 UNIVERSITY 
 
 OF 
 
 NOTE ON WATER-SUPPLY. 
 
 The human race must have recognized at an early period 
 the value of an abundant supply of pure and refreshing 
 water. Pastoral communities would be obliged to guide 
 their movements along lines that would keep them within 
 convenient reach of streams and pools for watering cattle; 
 agricultural nations could only establish themselves where 
 water was abundant. Of the two classes, the former would 
 be much less likely to develop soil-pollution, and, accord- 
 ingly, we find that it is with agricultural and manufac- 
 turing centers i. e., towns and cities that the serious 
 difficulties with regard to water-supply arise. Drainage 
 areas are easily polluted; in all the civilized countries the 
 streams receive more or less sewage, and are correspond- 
 ingly offensive to the senses and dangerous to health. 
 The subsoil is better adapted to deal with normal pollu- 
 tion, but its powers are not inexhaustible, and in time 
 wells and springs become unsafe. The usual course of 
 events in this matter is well portrayed by Sextus Julius 
 Frontinus, who was Water Commissioner of Rome from 
 A. D. 97 to 103, and who has left us a comprehensive ac- 
 count of the water-supply of that city. He says that from 
 the building of the city until its four hundred and forty- 
 first year (312 B. c.), the citizens were supplied with water 
 from the Tiber, or from wells and springs. These springs, 
 as with other nations of antiquity, were often credited 
 
14 NOTE ON WATEK -SUPPLY. 
 
 with healing powers, either due to some medicinal in- 
 gredients or because the locality was supposed to be the 
 abode of a minor deity, whose favor could be secured 
 in various ways. The Roman water-supply became 
 unsatisfactory; aqueducts were built, and these supplied 
 the city for centuries. Two of the original aqueducts 
 are still in use, supplying modern Rome with excellent 
 water. The quantity of water supplied to the ancient 
 city during the height of the development of the aqueduct 
 system the early part of the second century of the Chris- 
 tian era is not accurately known, but Clemens Herschel, 
 after careful examination of all data, fixes it at about 50,- 
 000,000 gallons a day. Most of the supply was of good 
 quality, but some of the aqueducts delivered river water 
 that was frequently turbid. No proper filtering basins 
 were in vise, but special interrupting chambers assisted 
 in getting rid of the coarser suspended matters. 
 
 Much less is known of the water-supply of the other 
 great cities of the ancient world. Aristotle, in his "Con- 
 stitution of Athens," refers to an official designated " Super- 
 intendent of Springs," which shows that municipal hygiene 
 was not wholly overlooked in that city. Jerusalem, during 
 its influential period, was apparently well supplied with 
 water. The remains of underground conduits have been 
 lately discovered, including a tunnel cut through rock 
 to a point distant about 300 meters in a direct line, but 
 an actual length much greater on account of the tortu- 
 ous course. This tunnel was probably executed in the 
 reign of Hezekiah (eighth century B. c.). An inscription 
 found on the interior wall some years ago, states that the 
 tunnel was bored from each end and the borers met nearly 
 
NOTE ON WATER-SUPPLY. 15 
 
 in line. It leads from a spring, now called the Virgin's 
 Spring (considered as identical with the ancient Gihon), 
 to a point near the Pool of Siloam, at the southeast corner 
 of the city. 
 
 In common with the general decline of intelligence and 
 morals which affected Europe during the thousand years 
 from the fifth to the fifteenth century, the protection of 
 the water-supply was but little regarded. The aqueducts 
 of Rome, Athens, and Lyon fell into disuse, and ev.en at 
 present are mostly represented by a few scattered ruins 
 studied only by the antiquary and historian. 
 
 It is not appropriate to discuss the engineering features 
 of ancient or modern water-supply, but it is worth while 
 to correct a wide-spread error in regard to the Roman 
 engineers. It is often said that they did not know that 
 water will rise to its original level, and, therefore, built 
 extensive aqueducts to carry water over valleys. The fact 
 is that they were as fully aware of the principle as modern 
 engineers, but it was usually cheaper for them to build the 
 aqueducts than to use inverted siphons. They did use the 
 latter at times. In the first century of the Christian era, 
 an aqueduct for supplying Lyon (Lugdunum) was pro- 
 vided with a series of seven lead pipes, each about 20 cen- 
 timeters in diameter, to carry water across a deep valley. 
 
NATURAL HISTORY AND CLASSIFICATION OF 
 WATER. 
 
 Pure water is an artificial product. Natural waters 
 always contain foreign matters in solution and suspension, 
 varying from mere traces to very large proportions. The 
 properties, effects, and uses of water are considerably 
 modified by these ingredients, and the object of analysis is 
 to ascertain their character and amount. Since these are 
 largely dependent on the history of the water, a classifica- 
 tion based on this will be convenient. We may distinguish 
 four classes of natural waters : 
 
 Rain Water. Water precipitated from the atmosphere 
 under any conditions, and therefore including dew, frost, 
 snow, and hail. 
 
 Surjace Water. All collections of water in free contact 
 with the atmosphere, as in streams, seas, lakes, or ponds. 
 
 Subsoil or Ground Water. Water not in free contact 
 with the atmosphere, percolating or flowing through soil 
 or rock at moderate distance below the surface, and de- 
 rived in large part from the rain or surface water of the 
 district. 
 
 Deep or Artesian Water. Water accumulated at con- 
 siderable depth below the surface, from which the subsoil 
 water of the district has been excluded by difficultly per- 
 meable strata. 
 
 Rain water, when gathered in the open country and 
 in the later period of a prolonged rain or snow, is the purest 
 
 16 
 
SURFACE WATER. 17 
 
 form of natural water. When collected directly, it con- 
 tains but little solid matter, this consisting principally of 
 ammonium compounds and particles of organic matter, 
 living and dead, gathered from the atmosphere. In dis- 
 tricts near the sea an appreciable amount of chlorids will 
 be present. It is obvious that a prolonged rain will wash 
 out the air, but since storms are usually attended by wind, 
 fresh portions of air are continually flowing in, and thus 
 the water never becomes perfectly pure. Rain water 
 collected in inhabited districts is usually quite impure. 
 
 Surface Water. Rain water in part flows off on the 
 surface, and gains in the proportion of suspended and dis- 
 solved matters, the former being found in large amount 
 when the rainfall is profuse. The wearing action of water 
 is dependent on the amount 'and character of these sus- 
 pended materials. From th,e higher levels of a watershed, 
 the streams, more or less in the form of torrents, gather 
 into larger currents, and, reaching lower levels, become 
 slower in movement, and deposit much of the suspended 
 matter. By admixture of the waters from widely separated 
 districts the character and amount of the dissolved matters 
 are much modified. 
 
 It is obviously impossible to establish close standards of 
 composition for surface waters. In the case of rain water, 
 falling on the surface of undisturbed, unpopulated terri- 
 tory, the amount of solids dissolved will be small, and 
 will consist principally of carbonates and sulfates. The 
 water of lakes and rivers is, however, in part derived from 
 springs, which may proceed from great depths, and thus 
 introduce substances not easily soluble in surface water, 
 nor derivable from the soil of the district. 
 
1 8 HISTORY AND CLASSIFICATION. 
 
 The exposure to light and air which surface water under- 
 goes, results in the absorption of oxygen and loss of car- 
 bonic acid, together with the oxidation of the organic 
 matter. The diminution of the rapidity of the current 
 permits the deposition of the suspended matters, and this 
 occurs especially as the river approaches the sea, not only 
 from the retarding influence of the tidal wave, but from 
 the precipitating action of the salt water. 
 
 Subsoil Water. Water that penetrates the soil passes 
 to various depths, according 'to the porosity and arrange- 
 ment of the strata. As a rule, it descends until it reaches 
 but slightly pervious formations, upon the level of which 
 it accumulates. In the upper layer of soil it dissolves 
 mineral and organic ingredients, and becomes impreg- 
 nated with microorganisms, through the agency of which 
 the organic matter undergoes important transformations. 
 The water, constantly accumulating, gradually flows 
 along the incline of the impervious stratum, or through its 
 fissures, and may either pass downward or emerge in the 
 form of a spring. 
 
 Much difference is observed in the composition of sub- 
 soil waters, but as a general rule they contain small amounts 
 of mineral substances and organic matter. In popu- 
 lated districts, however, a marked change is produced 
 through admixture with water containing animal and 
 vegetable products in various stages of decomposition. 
 It is especially the organic matter containing nitrogen 
 that is of importance. These are mostly unstable, and 
 decompose, partly by oxidation, partly by splitting up 
 into simpler forms; changes in most cases brought about 
 by microorganisms. The nitrogen is in part converted 
 
DEEP WATER. 19 
 
 into ammonium compounds, but a considerable portion 
 suffers further oxidation, and in association with the 
 mineral substances present forms nitrites and nitrates, 
 especially the latter. This is called "nitrification." 
 
 Nitrification takes place under the influence of microbes, 
 the habitat of which does not extend more than a few 
 yards below the surface of the soil. Several microorganisms 
 with active nitrifying powers have been isolated and de- 
 scribed. The nitrifying action is often exerted upon the 
 ammonium compounds formed from the organic matter. 
 The presence of some substance capable of neutralizing 
 acids is usually necessary to continuous action. Calcium 
 and magnesium carbonates fulfil this function. Nitrates 
 are the final result of this action; nitrites are present at 
 any given time only in small quantity. Denitrification 
 that is, the reduction of nitrates and nitrites to ammonium 
 compounds takes place also under the influence of mi- 
 crobes, and is especially apt to occur when considerable 
 quantities of decomposing organic matter are introduced. 
 Several species of denitrifying bacilli have been described. 
 A partial reduction sometimes occurs, and a notable pro- 
 portion of nitrites is found, but in the presence of actively 
 decomposing organic matter, such as that in sewage, a 
 complete reduction, even to the liberation of nitrogen, 
 may occur. 
 
 Deep Water. Water which penetrates the fissures of 
 the fundamental rock-formations may pass to great depths, 
 and by following the lines of the lowest and least permeable 
 strata may be transported to points far removed from those 
 at which it was originally collected. The chemical changes 
 thus induced include most of those which take place at 
 
20 HISTORY AND CLASSIFICATION. 
 
 higher points, but the increase of pressure and temperature 
 confers increased solvent power. Carbonic acid will 
 accumulate under conditions favorable to the solution of 
 calcium, magnesium, and iron carbonates, and iron, and 
 manganese oxids may be converted into carbonates and 
 then dissolved. Sulfates are reduced to sulfids, and these 
 subsequently, by the action of carbonic acid, yield hy- 
 drogen sulfid. Organic matter, living and dead, plays 
 an important part, determining the reduction of ferric 
 compounds to ferrous, and of the sulfates to sulfids, and 
 is itself converted ultimately into ammonium compounds, 
 notable quantities of which are often found in deep waters. 
 Further, it is found that nitrates and nitrites are present 
 only in small amount, except from certain strata rich in 
 organic matter. In some cases the water acquires very 
 high temperature, and dissociation of rocks occurs w r ith 
 solution of considerable amounts of silicic acid, which is 
 ordinarily but sparingly soluble in water. 
 
 Masses of w r ater thus accumulated under heat and pres- 
 sure may find their way to the surface either through 
 natural fissures or be reached by borings. 
 
 While no absolute unchangeable line can be drawn be- 
 tween deep and subsoil waters, yet it will in most cases be 
 found that the deep water of a given district, whether 
 obtained through natural or artificial channels, will be 
 decidedly different in composition from the subsoil or sur- 
 face water of the same, and that the rocks passed through 
 in such cases will be characterized by one or more strata, 
 difficultly permeable to water, and therefore preventing 
 direct communication. The characteristic differences be- 
 
DEEP WATER. 21 
 
 tween surface, subsoil, and deep waters are clearly in- 
 dicated in the table of analyses given in the appendix. 
 
 The fact that mere depth is not the essential difference 
 between the two classes of waters is shown by comparison 
 between the composition of the water from a well at Barren 
 Hill, near the northern border of Philadelphia County, 
 and a deep well at Locust Point, Baltimore. The former 
 is a dug well, 130 feet deep; the latter is an artesian boring 
 of 128 feet, which in its descent passes through 4 feet of 
 solid rock. The deeper well is evidently supplied by 
 subsoil water. The artesian well, though located 100 
 yards from a brackish, sewage-laden estuary, evidently 
 derives no water from it. 
 
 BARREN HILL LOCUST POINT 
 
 WELL. WELL. 
 
 Total solids, 470.00 Less than 100.00 
 
 Chlorin, /___i2O.oo 4.68 
 
 Nitrogen as nitrates, 22.00 none 
 
ANALYTIC OPERATIONS. 
 
 SANITARY EXAMINATIONS. 
 
 COLLECTION AND PRELIMINARY EXAMINATION 
 OF SAMPLES. 
 
 Great care must be taken in collecting water samples, 
 in order to secure a fair representation of the supply and 
 
 to avoid introduction of 
 foreign matters. The 
 five-pint green glass- 
 stoppered bottles used 
 for holding acids are 
 suitable for containing 
 the samples. The con- 
 tents of one such bottle 
 will suffice for most 
 sanitary or technic ex- 
 aminations. Figure i 
 shows a boxed bottle 
 known as " Banker's 
 Glass Can," which I 
 FIG. i. have found very con- 
 
 venient for transporta- 
 tion. It is provided with a hinged lid which can be 
 fastened, if deemed necessary, by a padlock. The green 
 glass-stoppered bottles may be fitted in such an arrange- 
 
 22 
 
SANITARY EXAMINATIONS. 23 
 
 ment. Crated demijohns are now made for forwarding 
 water. The larger sizes are well adapted for samples 
 which are to be subjected to elaborate analysis. A boxed 
 bottle called the "New Era demijohn" is suitable for water 
 samples. Stone jugs, casks, or metal vessels should not 
 be employed. The bottles used must be thoroughly rinsed 
 several times with the water to be examined, filled, and the 
 stopper, tied down or fastened by stretching a rubber 
 finger-cot over the stopper and lip. If corks are used, 
 they should be new and thoroughly rinsed. Wax, putty, 
 plaster, or similar material should not be used. 
 
 In taking samples from lakes, slow streams, or reser- 
 voirs, it is necessary to submerge the bottle so as to avoid 
 collecting any water that has been in immediate contact 
 with the air. In the examination of public water-supplies, 
 the sample should be drawn from a hydrant in direct con- 
 nection with the main, and not from a cistern, storage-tank, 
 or dead end of a pipe. In the case of pump-wells, a few 
 gallons of water should be pumped out before taking the 
 sample, in order to remove that which has been standing 
 in the pipe. 
 
 In all cases care should be taken to fill the vessel with 
 as little agitation with air as possible. 
 
 It is important that with each sample a record be made 
 of those surroundings and conditions which might in- 
 fluence the character of the water, particularly in reference 
 to sources of pollution, such as proximity to cesspools, 
 sewers, or manufacturing establishments. The character 
 and condition of the different strata of the locality should 
 be noted if possible. 
 
 Determinations of nitrogen existing as ammonium com- 
 
ANALYTIC OPERATIONS. 
 
 pounds and as organic matter, and of oxygen-consuming 
 power, should be made upon the sample in the original 
 condition, whether turbid or clear, but all other estima- 
 tions should be made upon the clear liquid. 
 Turbid waters may be clarified by stand- 
 ing or by filtration; for the latter purpose 
 Schleicher & Schull's extra heavy No. 598 
 paper is the best. In many cases the sus- 
 pended matter can not be entirely removed 
 by filtration, and subsidence must be re- 
 sorted to. The use of a small quantity of 
 alum, or aluminum hydroxid, as described 
 in the section on the purification of water, 
 will sometimes be applicable as a means of 
 clarifying samples. For the quantitative 
 determination, the sediment from a known 
 volume of the water is collected on a tared 
 filter, dried, and weighed. 
 
 The water from newly-dug wells is 
 generally turbid, and the determinations 
 are best made after filtration; but the 
 results will be unsatisfactory, showing a 
 higher proportion of organic matter than 
 will be found when the supply becomes 
 clear. For taking samples at consider- 
 able depths the bottle shown in Fig. 2 
 will answer, but samples so collected will 
 not serve for determination of dissolved 
 
 FIG. 2. 
 
 gases. 
 
 Collection of Samples for Bacteriologic Exam- 
 ination. Bacteriologic examinations are of little value 
 
SANITARY EXAMINATIONS. 25 
 
 unless made promptly on samples that have been collected 
 with precautions against contamination. The inoculation 
 of the culture-medium is best done at the source. If this 
 is not possible, glass-stoppered bottles holding about 
 200 c.c., which have been thoroughly sterilized, with 
 stoppers in place, in a hot-air oven at 100 C., must be 
 used for collection. They should be rinsed on the outside 
 with the water, dipped below the surface, the stopper 
 withdrawn, and again inserted when the bottle is full. If 
 these are to be transported any distance, they should be 
 packed in ice. For the collection of samples below the 
 surface of the water, the bottle shown in the cut (Fig. 2) 
 is recommended by Abbott. The bottle having been pre- 
 viously thoroughly sterilized is sunk to the proper depth and 
 the stopper is then lifted by a special cord and held until the 
 bottle is full, when, the cprd being released, the stopper 
 falls. Before taking out portions for test the lip and stopper 
 must be thoroughly sterilized by strong alcohol and by care- 
 ful heating, and, after cooling, washing with sterilized 
 water. 
 
 Color. A colorless glass tube, two feet long and two 
 inches in diameter, is closed at each end with a disc of 
 colorless glass. An opening for filling and emptying the 
 tube should be made at one end, either by cutting a small 
 segment off the glass disc, or cutting out a small segmental 
 section of the tube itself before the disc is cemented on. 
 A good cement for such purposes is the following: 
 
 Caoutchouc, 2 parts. 
 
 Mastic, 6 
 
 Chloroform, 100 " 
 
26 ANALYTIC OPERATIONS. 
 
 The ingredients are mixed and allowed to stand for a 
 few days. The cement should be used as soon as solution 
 is effected, as it becomes viscid on standing. 
 
 The tube must be about half filled with the water to be 
 examined, brought into a horizontal position, level with 
 the eye, and directed toward a brightly illuminated white 
 surface. The comparison of tint has to be made between 
 the lower half of the tube containing the water under ex- 
 amination and the upper half containing air only. 
 
 A more convenient form of tube is made by attaching 
 brass screw-nipples to each end of the tube, and closing 
 these by screw-caps carrying plate-glass discs. Such tubes 
 can be obtained from dealers in chemical apparatus. It is 
 obvious that various methods of comparing color and tur- 
 bidity may be devised, but data so obtained are of little 
 analytic value, and even that little is limited to samples 
 closely analogous in character. 
 
 Hazen has devised a standard for color comparison 
 which he claims as capable of most satisfactory use on 
 all ordinary waters. It is based upon the modification of 
 a solution of platinum chlorid by a solution of cobalt 
 chlorid, as follows: 
 
 1.246 grams of potassium platinum chlorid (correspond- 
 ing to 0.5 gram of Pt) and i gram of cobalt chlorid (corre- 
 sponding to 0.25 gram of Co) are dissolved in water, 100 
 c.c. of strong hydrochloric acid added, and the solution 
 made up to 1000 c.c. It keeps well, even when exposed 
 to the light. For comparison, i, 2, 3, etc., of the stock 
 solution are diluted to 50 c.c. in Nessler tubes. These 
 correspond to o.i, 0.2, 0.3, etc., degrees of the color standard. 
 These also keep for a long time if protected from dust. 
 
SANITARY EXAMINATIONS. 27 
 
 Direct comparison in 200 mm. tubes is generally sufficient. 
 If the shade of color is not exactly that of the water, more 
 cobalt may be added, the platinum being constant. Hazen 
 expresses the result in any case in terms of "the amount 
 of platinum in parts per 10,000, which in acid solution 
 with so much cobalt as will match the hue, produces an 
 equal color in distilled water." 
 
 Lovibond's tintometer is probably the best means of 
 making color comparisons. 
 
 Odor. Put about 150 c.c. of the water into a clean, 
 wide-mouth 250 c.c. stoppered bottle, which has been 
 previously rinsed with the same water; insert the stopper 
 and warm the water in a water-bath to 100 F. Remove 
 the bottle from the water-bath and shake it rapidly for a 
 few seconds; remove the stopper, and immediately note if 
 the water has any smell v Insert the stopper and repeat 
 the test. 
 
 In a polluted water the odor will sometimes give a clue 
 to the origin of the pollution. 
 
 Turbidity. Several methods for expressing degree of 
 turbidity have been used. Whipple and Jackson, after 
 comparing these, find that finely powdered diatomaceous 
 earth is satisfactory. The material is ignited, ground to a 
 powder that will pass through a 2oo-mesh sieve, dried at 
 1 00 C., cooled in a desiccator, and kept in a well-stoppered 
 bottle. A strong standard is prepared by adding i gram 
 of this powder to i liter of water, and 12 dilute standards 
 by mixing quantities of the strong standard in amount 
 from i to 10 c.c., increasing by 0.5 c.c., to quantities of 
 distilled water sufficient to make 100 c.c. in each case. 
 The dilute standards are kept in tightly corked tubes and 
 
28 ANALYTIC EXAMINATIONS. 
 
 shaken several times when used for comparison. If new 
 corks are used, they should well boiled in water to extract 
 coloring-matter. If the sample is of high turbidity, it 
 must be diluted by a known volume of water. The record 
 is made by noting the strength of the standard tube that 
 is nearest in turbidity to the sample, the tubes being held 
 together and viewed from the side. The tube containing 
 the sample must be uniform in size and quality with those 
 containing the standard. 
 
 Reaction. The determination of reaction is usually 
 made by the addition of a neutral solution of litmus to the 
 water. If an acid reaction is obtained, the water should 
 be boiled in order to determine if it is due to carbonic 
 acid. Some of the more delicate indicators, such as 
 phenolphthalein, lakmoid, and erythrosin, may be used 
 with advantage for these tests. The latter possesses the 
 advantage that it is unaffected by carbonic acid, but de- 
 tects even traces of free mineral acid. It is neutral, also, 
 to many normal metallic salts, such as ferrous sulfate, 
 which are acid to litmus. Ferric salts, however,- are acid 
 to lakmoid. Its color-changes are the same as those of 
 litmus /. e., red with acids and blue with alkalies. 
 
 Phenolphthalein is usually applied to the detection of 
 weak acids, such as carbonic acid and the organic acids. 
 In acid and neutral solutions it is colorless; in alkaline, 
 red. Nearly all waters contain carbonic acid, and will 
 therefore bleach a solution of phenolphthalein which has 
 been reddened by a small amount of alkali. 
 
SANITARY EXAMINATIONS. 
 
 2 9 
 
 TOTAL SOLIDS. 
 
 A platinum basin holding 100 c.c. will be found con- 
 venient for this determination. This will weigh about 
 45 grams. It should be kept clean and smooth by fre- 
 quent burnishing with sand, a little of which should be 
 placed in the palm of the hand, moistened, and the dish 
 gently rubbed against it. Very fine sea-sand with round, 
 smooth grains is the only kind suitable for this purpose. 
 Coarse river sand, tripoli, or other rough scouring-powders 
 must not be employed. If proper 
 care is taken, the luster of the 
 metal will be retained, and the 
 loss in weight will be trifling. 
 The inner surface can generally 
 be cleaned by treatment, with 
 hydrochloric acid, rinsing, and, 
 if necessary, burnishing with 
 sand. Neglect of these precau- 
 tions will soon lead to serious 
 damage to the dish. A small, 
 smooth slab of iron or marble is 
 
 convenient to set it on while cooling. When being heated 
 over the naked flame, the dish should rest on a triangle of 
 iron wire, covered with pipe-stems. Dishes of pure nickel 
 are not satisfactory substitutes for those of platinum. 
 
 Platinum-pointed forceps should be used in handling 
 the dish. The platinum terminals may be kept bright 
 and clean by the use of sand. 
 
 The low-temperature burner, used as shown in figure 3, 
 will be found a very convenient substitute for the water- 
 
 FIG. 3. 
 
30 ANALYTIC OPERATIONS. 
 
 bath and hot-air oven. The inlet pipe is very short and 
 soon becomes so hot as to injure the rubber tube. To 
 avoid this it may be lengthened by means of a piece of 
 J-inch gas-pipe, or the junction may be wrapped with a 
 rag, the ends of which dip into water. By capillary at- 
 traction the rag is kept moist and cool. 
 
 The determination of total solids is made by evaporating 
 100 c.c. of the water in the platinum basin, which has 
 been previously heated almost to redness, allowed to cool 
 for ten minutes, and weighed. The operation is conducted 
 at a moderate heat. When the residue appears dry, the 
 heat may be increased slightly for some minutes. The 
 above method will answer in most cases. In waters of 
 exceptional purity it may be advisable to use larger quan- 
 tities, such as 250 c.c. When the residue contains deli- 
 quescent bodies, the determination will not be accurate, 
 and when appreciable amounts of magnesium and chlorin 
 are present, a decomposition will occur toward the close 
 of the evaporation by which magnesium oxid will be formed 
 and hydrogen chlorid escape. 
 
 The irregular decomposition occurring during the evap- 
 oration may be largely prevented by adding 0.005 gram of 
 sodium carbonate to each 100 c.c. of the sample taken. 
 This converts magnesium and calcium salts into carbonates. 
 The sodium carbonate is conveniently kept in the form of 
 solution of such strength that i c.c. contains o.ooi gram. 
 The weight of the carbonate is, of course, to be deducted 
 from the weight of the residue. Drown and Hazen have 
 carefully investigated this method and have found it avail- 
 able for a more satisfactory determination of the loss on 
 ignition. For this process they place the platinum basin 
 
SANITARY EXAMINATIONS. 31 
 
 containing the residue within another similar basin of such 
 size that an air-space of about one-half of an inch is left all 
 around the inner dish, which is supported upon a spiral of 
 platinum that rests on the bottom of the outer' dish. Over 
 the inner dish is suspended a disc of platinum foil to reflect 
 the heat. The outer dish is heated to bright redness. 
 
 After the weight of the residue is obtained, the dish 
 should be cautiously heated to low redness and the effect 
 noted. Nitrates and nitrites, calcium and magnesium 
 carbonates, are decomposed; ammonium salts are driven 
 off; potassium and sodium chlorids are also driven off 
 if the temperature is high. Organic matter is at first 
 charred, and by continued heating burned off. When the 
 quantity of nitrates is considerable, slight deflagration may 
 be observed, or the production of red fumes of nitrogen 
 dioxid. The organic matter, in decomposing, not infre- 
 quently develops odors which indicate its character or 
 source. These are more satisfactorily observed when a 
 rather large quantity, say 250 c.c., is evaporated at a low 
 heat, preferably on a water-bath. 
 
 In water of high organic purity, the residue on heating 
 will give no appreciable blackening nor odor, while in 
 forest streams charged with vegetable matter derived from 
 falling leaves, very decided blackening without unpleasant 
 odor will be noticed. The loss of weight after heating 
 can not be taken as a measure of the organic matter, ex- 
 cept when present in relatively large amount. 
 
32 ANALYTIC OPERATIONS. 
 
 CHLORIN. 
 
 Solutions Required: 
 
 Standard Silver Nitrate. Dissolve about five grams of 
 pure re crystallized silver nitrate in distilled water, and 
 make the solution up to 1000 c.c. The amount of chlorin 
 to which this is equivalent may be determined as follows: 
 Several grams of pure sodium chlorid are finely powdered 
 and heated over a Bunsen burner for five minutes, not quite 
 to redness. When cold, 0.824 gram are dissolved in water 
 and the solution made up to 500 c.c. Twenty-five c.c. of 
 this should be treated as below, and the amount of silver 
 solution required noted. Each c.c. of the sodium chlorid 
 solution is equivalent to o.ooi gram chlorin. 
 
 Potassium Chromate. Five grams of potassium chro- 
 mate are dissolved in 100 c.c. of distilled water. A solu- 
 tion of silver nitrate is added until a permanent red pre- 
 cipitate is produced, which is separated by filtration. 
 Analytic Process : 
 
 If a preliminary test shows the chlorin to be present in 
 considerable amount, the determination may be made on 
 100 c.c. of the water without concentration. If, how- 
 ever, there is but little present, 250 c.c. should be evap- 
 orated to about one-fifth, best with the addition of a little 
 sodium carbonate, and the determination made on the 
 concentrated liquid after cooling. 
 
 The water is placed in a porcelain dish or in a beaker 
 standing on a white surface, a few drops of potassium 
 chromate solution added, and standard silver nitrate solu- 
 tion run in from a buret until a faint red color of silver 
 chromate remains permanent on stirring. The proportion 
 
SANITARY EXAMINATIONS. 33 
 
 of chlorin is then calculated from the number of c.c. of 
 silver solution added. Greater accuracy is secured by 
 operating in yellow light. A second determination may 
 be made, using as a comparison the liquid first titrated, 
 the red color having been previously discharged by a few 
 drops of sodium chlorid solution. 
 
 The water should always be as nearly neutral as possible 
 before titration. If acid, it may be neutralized by the 
 addition of sodium carbonate. 
 
 The residue obtained by evaporating the water with 
 sodium carbonate, as described in connection with the de- 
 termination of the total solids, will often serve conveni- 
 ently for estimating the chlorin. It is best to use 200 c.c. 
 of the sample and redissolve the residue in about 50 c.c. 
 of distilled water, rubbing the sides of the dish well with a 
 rubber-tipped rod, and the,n titrating as indicated above. 
 
 Chlorin may be determined by Volhard's method, 
 adding excess of standard silver solution, and then titrating 
 the residual silver by means of thiocyanate solution. Free 
 nitric acid does not interfere with this method, but it is 
 necessary to remove the silver chlorid before titrating with 
 thiocyanate. The following description of the method 
 is adapted from Button's "Volumetric Analysis": 
 Solutions Required : 
 
 Decinormal Thiocyanate. About 10 grams of the 
 potassium compound or 8 grams of the ammonium com- 
 pound are dissolved in a liter of water and the solution 
 adjusted by means of standard silver nitrate solution. 
 
 Decinormal Silver Nitrate. This may be prepared by 
 dissolving pure silver in nitric acid, since as noted above a 
 slight excess of the acid does not interfere with the test, 
 c 
 
34 ANALYTIC OPERATIONS. 
 
 Ferric Indicator, A saturated solution of ammonium 
 ferric sulfate. 
 
 Nitric A cid. This must be free from the lower oxids 
 of nitrogen. They may be removed by adding about one- 
 fourth volume of water and boiling until colorless. The 
 acid should be kept from the light. 
 Analytic Method : 
 
 f A suitable quantity of the water is treated with a slight 
 excess of decinormal silver nitrate, the chlorid collected by 
 shaking, and an aliquot part of the liquid removed by 
 decantation or nitration. To this is added 10 c.c. of the 
 nitric acid and 5 c.c. of the ferric indicator, and thiocyanate 
 is run in until a faint permanent brown is produced in the 
 liquid. This marks the precipitation of all the silver, and 
 the formation of ferric thiocyanate. The color is seen best 
 by holding the flask against a background of white paper. 
 As the point of precipitation of the last portions of silver 
 is approached, the precipitate becomes flocculent and 
 settles easily. The excess of silver is deducted from the 
 total used; the remainder is the amount required for the 
 chlorin in the water. 
 
 NITROGEN IN AMMONIUM COMPOUNDS AND IN 
 ORGANIC MATTER. 
 
 Apparatus Required : 
 
 Distilling Apparatus. That shown in figure 4 has been 
 found to be convenient. The still consists of a glass 
 retort of about 1000 c.c. capacity. The beak of the retort 
 should incline slightly upward, to prevent contamination 
 by splashing. At about seven centimeters from the end 
 it should be bent at a right angle, and drawn out so as to 
 
SANITARY EXAMINATIONS. 
 
 35 
 
 enter the condensing worm for such a distance as to ter- 
 minate beneath the level of the water. 
 
 The condenser shown in the figure is a copper tank, 
 33 cm. high, 15 cm. wide, and of length proportioned to 
 the number of distilling vessels operated. The condensing 
 tube is shown only as emerging from the bottom of the tank. 
 
 FIG. 4. 
 
 Glass worms are apt to break, and it is more satisfac- 
 tory to use block tin. A piece of rubber tubing is drawn 
 over the junction between the retort neck and worm. A 
 rapid current of cold water should be maintained through 
 the condenser. The heat is applied by means of the low- 
 
36 ANALYTIC OPERATIONS. 
 
 temperature burner, the iron ring of which is removed so 
 that the retort rests directly on the gauze. 
 
 To prevent overheating of the upper part of the retort, 
 a sheet of thick asbestos board about 20 cm. in diameter, 
 with a central opening about 5 cm. in diameter, may be 
 placed on the gauze. With this arrangement the heat is 
 under control, and the danger of breaking the retort is 
 slight. It is advisable to protect the retort from drafts 
 of cold air, which may be done with a cone made of thin 
 sheet asbestos. 
 
 Figure 5 shows the distilling arrangement used in the 
 laboratory of the testing station of the Philadelphia ni- 
 tration plant. The cut was loaned by the Journal 0} the 
 American Chemical Society, and the description is tran- 
 scribed from the paper published in that journal by G. E. 
 Thomas and C. A. Hall. The flask has a side-neck and 
 ground-glass stopper, and bulb of a capacity of nearly 
 2000 c.c. It is supported on wire gauze resting on a sheet- 
 iron cylinder. The condensing worm is of block tin con- 
 nected to the side-neck by rubber tubing, the glass extending 
 into the tin for several centimeters beyond the point of 
 contact of the rubber. Another piece of rubber tubing 
 covers the point of contact of the first piece with the metal 
 tube. The latter is about 9 mm. internal diameter, about 
 12 mm. external, and is coiled into a helix 6 cm. internal 
 diameter and n cm. pitch. The caliber of the tube is 
 expanded slightly at the upper end to allow of insertion 
 of the side-neck of the flask and is contracted for a few 
 centimeters at the outlet. The condenser is made of cold 
 rolled sheet-copper (commercially known as 24 ounce), 
 braced within and provided with a lid hinged at the back 
 
SANITARY EXAMINATIONS. 
 
 37 
 
 and overlapping slightly in front. The water is supplied 
 below and overflows at the top. The ground stoppers and 
 side-neck attachment permit of introduction of samples 
 and solutions without disconnecting the flasks. A long- 
 necked funnel will be convenient for this purpose. 
 
 Figure 6 shows an elaborate distilling apparatus ar- 
 ranged by R. S. Weston. It has the advantage that the 
 distillate is received on the side on which the distilling 
 
ANALYTIC OPERATIONS. 
 
 C/arrrjo 
 
 FIG. 6. 
 
SANITARY EXAMINATIONS. 
 
 39 
 
 flask is placed. The details of construction are indicated 
 in the figure. The condenser may be made of copper or 
 japanned, galvanized iron. 
 
 Scale lMin.= l foot. 
 
 FIG. 7. 
 
 Another convenient form of apparatus is shown in figure 
 7. It is employed in the laboratory of the Massachusetts 
 
ANALYTIC OPERATIONS. 
 
 State Board of Health. The joint between the flask and 
 condenser is made by means of a sound cork, into which 
 the condensing tube fits closely; the tube from the flask 
 is made slightly smaller than the condensing tube, and 
 passes into it for about four centimeters. 
 
 A form of condenser applicable to distillations of this 
 character has been devised by Cribb 
 and is shown in figure 8. The vapor 
 passes to a narrow annulus by the 
 tube A; the cooling water enters 
 the central portion and overflows, 
 running down the outside wall, 
 being collected by the projecting 
 rim and carried off by the tube G. 
 For water analysis a retort with the 
 neck bent at an obtuse angle may 
 be used, or a flask with side tube. 
 \ i JJJY In the latter case, the tube must 
 
 \J^T~[ ) leave the flask at a slight angle 
 
 upward, and about midway be bent 
 at a slight obtuse angle downward. 
 This prevents contamination of the 
 distillate by spurting. The draw- 
 ing shows the form given by Cribb, 
 but experience has shown that 
 
 more space should be allowed between the inner and 
 outer wall at the lowest point, and that the catch-basin 
 should be large. The tube, G, should be at least three 
 times the caliber of F. It will often be advantageous to 
 wrap a piece of muslin around the body of the apparatus. 
 Cylinders /or Comparison-color Tests, about 2.5 centi- 
 
 FIG. 8. 
 
SANITARY EXAMINATIONS. 41 
 
 meters in diameter and holding 100 c.c., made of colorless 
 
 glass. 
 
 Solutions Required : 
 
 Sodium Carbonate. Fifty grams of pure sodium carbon- 
 ate are strongly heated, dissolved in 250 c.c. of distilled 
 water, and the solution boiled down to 200 c.c. 
 
 Ammonium-jree Water. If the distilled water of the 
 laboratory gives a reaction with Nessler reagent, it should 
 be treated with sodium carbonate, about one grain to the 
 liter, and boiled until about one-fourth has been evapo- 
 rated. Ammonium-free water may be obtained by distill- 
 ing, in a retort, water made slightly acid with sulfuric acid. 
 
 Messrs. J. B. Weems, C. E. Gray, and E. C. Myers re- 
 commend the following method: Sodium dioxid is added 
 to ordinary water in the proportion of one gram to a liter, 
 and the liquid boiled for thirty minutes, or longer if the 
 amount of ammonium compounds is high. It is then 
 cooled and the flask kept closed. Flasks holding several 
 liters are most convenient. If the water be distilled, the 
 distillate may also be used for the preparation of standard 
 nitrate and nitrite solutions. 
 
 Standard Ammonium Chlorid. Dissolve 0.382 gram of 
 pure dry ammonium chlorid in 100 c.c. of ammonium- 
 free water. For use, dilute i c.c. of this solution with 
 pure water to 100 c.c. One c.c. of this dilute solution con- 
 tains o.ooooi gram of nitrogen. 
 
 Nessler Reagent. Dissolve 35 grams of potassium iodid 
 in 100 c.c. of water. Dissolve 17 parts of mercuric chlorid 
 in 300 c.c. of water. The liquids may be heated to aid 
 solution, but must be cooled before use. Add the mercuric 
 chlorid solution to that of the potassium iodid, until a 
 
42 ANALYTIC OPERATIONS. 
 
 permanent precipitate is produced. Then dilute with a 
 20 per cent, solution of sodium hydroxid to 1000 c.c., add 
 mercuric chlorid solution until a permanent precipitate 
 again forms, and allow to stand until clear. Nessler and 
 other reagents are best kept in glass-capped bottles, figure 
 9, in which the pipet may remain when not in 
 use. The solution improves by keeping. 
 
 Alkaline Potassium Permanganate. Dissolve 
 200 grams of potassium hydroxid, in sticks, and 
 8 grams of potassium permanganate, in a liter 
 of distilled water. 
 
 The solution may be boiled until about one- 
 FIG. 9 . fourth is evaporated, and then made up to a 
 liter with ammonium-free water. It will still 
 furnish some ammonium. Fox recommends to distil 50 
 c.c. with 500 c.c. of absolutely ammonium-free water, best 
 twice distilled with sulfuric acid, and note the ammonia 
 obtained. This quantity should be deducted in each anal- 
 ysis. The method of determining nitrogen by permanga- 
 nate, as given below, avoids the necessity for this pre- 
 liminary valuation of the solution. 
 Analytic Process : 
 
 The retort and condenser are thoroughly rinsed with 
 ammonium-free water, 500 c.c. of the water to be tested 
 introduced, about five c.c. of the sodium carbonate solu- 
 tion added to render the water alkaline, and some small 
 pieces of pumice-stone or fragments of pipe-stems heated 
 to redness and dropped in w r hile hot. The water is then 
 boiled gently until the distillate measures 50 c.c. The 
 distillate is transferred to one of the color- comparison 
 cylinders, and two c.c. of Nessler reagent added. A 
 
SANITARY EXAMINATIONS. 43 
 
 yellowish-brown color is produced, the intensity of which 
 is proportional to the amount of ammonium present. The 
 full color is developed in five minutes. This color is ex- 
 actly matched by introducing into another cylinder 50 
 c.c. of ammonium-free water, some of the standard am- 
 monium chlorid solution,- and two c.c. Nessler reagent, 
 as before. According as the color so produced is deeper 
 or lighter than that obtained from the water, other com- 
 parison liquids are prepared containing smaller or larger 
 proportions of the ammonium chlorid, until the proper 
 color is produced. 
 
 The distillation is continued, successive portions of 50 
 c.c. each collected, and tested until no reaction occurs 
 with Nessler reagent. The sum of the figures from the 
 several distillates gives the total nitrogen obtainable as 
 "free ammonia," so called. 
 
 If the quantity of ammonium is sufficient to cause a 
 precipitate, the color comparison can not be accurately 
 made. In most cases this will not be of serious moment, 
 as the quantity will be beyond the allowable limit. If 
 accurate determination be desired, it may be made by 
 dividing the first distillate into two equal parts, nessleriz- 
 ing one of these, and then, if necessary, diluting the second 
 part with ammonium-free water and nesslerizing this. 
 
 Occasionally, the evolution of ammonium hydroxid 
 continues indefinitely, and may even increase with succes- 
 sive distillates. This is due, not to ammonium compounds 
 existing as such, but to decomposition of certain nitro- 
 genous bodies, especially urea. In this case it is not ad- 
 visable to prolong distillation beyond the fourth or fifth 
 distillate, but to proceed to the following part of the process. 
 
44 ANALYTIC OPERATIONS. 
 
 The residue in the retort serves for the determination 
 of the nitrogen which is convertible into ammonium by 
 alkaline potassium permanganate the so-called "albu- 
 minoid ammonia" of Messrs. Wanklyn, Chapman, and 
 Smith. 
 
 Fifty c.c. of alkaline permanganate solution are added 
 to the retort, the distillation resumed, and the nitrogen 
 estimated in each 50 c.c. as before, deducting that yielded 
 by the permanganate. 
 
 It is a practice of some analysts to mix the distillates 
 of each of the foregoing operations, and make determina- 
 tions merely of the total nitrogen in each case. By so 
 doing, valuable information may be lost, since it has been 
 pointed out by several observers, notably Mallet and 
 Smart, that important information may be gained by 
 observing the rate of evolution of the ammonium hydroxid. 
 Mallet has further pointed out that many waters may con- 
 tain substitution ammoniums which may pass over before 
 the addition of the alkaline permanganate, but not be 
 correctly measured by nesslerizing. To avoid this error, 
 he suggested that two determinations be made on each 
 sample, one as above described, and the other by the 
 addition of alkaline permanganate without previous dis- 
 tillation. A higher figure may be obtained than the total 
 from the two distillations by the other process. 
 
 Since small quantities of ammonium compounds and 
 nitrogenous matters are everywhere present, the greatest 
 care should be exercised in order to avoid their introduc- 
 tion in any way during the course of the analysis. All 
 measuring vessels, cylinders, etc., should be thoroughly 
 rinsed before using. The temperatures of the distillates 
 
SANITARY EXAMINATIONS. 45 
 
 and standards should be approximately the same when the 
 colors are compared. 
 
 The Chemical Section of the American Association for 
 the Advancement of Science recommended the following 
 method for the application of the process: 
 
 200 c.c. of distilled water, together with 10 c.c. of 
 the sodium carbonate solution, are distilled down to 
 about 100 c.c. in the retort in which the analysis is to 
 be conducted, and the last portion of 50 c.c. nesslerized 
 to assure freedom from ammonium. Then 500 c.c. of the 
 water to be examined are added, and the distillation is 
 carried on at such a rate that about 50 c.c. are collected 
 in each succeeding ten minutes, and until a 50 c.c. measure 
 of distillate is obtained containing only an inappreciable 
 quantity of ammonia. In nesslerizing, five minutes are 
 to be allowed for the full development of color; after this, 
 no change takes place for many hours. 
 
 The distilling vessel is emptied and rinsed thoroughly, 
 200 c.c. of distilled water and 50 c.c. of alkaline perman- 
 ganate solution put in, and the liquid distilled down to 
 about 100 c.c., the last portions of the distillate being 
 tested to ascertain freedom from ammonium compounds, 
 another portion of 500 c.c. of the water to be tested is added, 
 and the distillation made as before. The difference be- 
 tween the "free" ammonia of the first operation and the 
 total ammonia of the second is to be taken as the "albu- 
 minoid" ammonia. 
 
 It is convenient to operate the distilling flasks in pairs, 
 using one of each pair for the permanganate process. Delay 
 and trouble of rinsing are thus avoided. Before beginning 
 an analysis, the greater part of the residue from a previous 
 
4 6 
 
 ANALYTIC OPERATIONS. 
 
 operation may be drawn off with a siphon, 200 c.c. of 
 distilled water added to each, and the liquids distilled 
 until the reagent shows freedom from ammonium com- 
 pounds. Suitable portions of the sample are then put in 
 each flask. 
 
 For nesslerizing and other 
 color comparisons, many forms 
 of apparatus have been pro- 
 posed. One, devised by Hehner, 
 is shown in figure 10. It con- 
 sists of a graduated cylinder with 
 a stop-cock near the base, by 
 which the liquid can be drawn 
 down at will. Two such cylin- 
 ders may be used one for the 
 nesslerized distillate, the other 
 for the comparison liquid. The 
 
 I 
 
 8.5 cc 
 
 FIG. 10. 
 
 FIG. ii a. 
 
 darker liquid is drawn out until the tints are equal, when 
 the relative volumes remaining will give the data for calcu- 
 lation. 
 
 H. J. Watson has modified the Hehner tube as shown 
 in figure n. The cuts were loaned by the Amer. Jour. 
 
SANITARY EXAMINATIONS. 
 
 47 
 
 of Pharmacy. The jar is 30 cm. long, 1.8 cm. in diameter, 
 and is graduated into cubic centimeters for about 20 cm. 
 from the base. At the side of the base a small tube pro- 
 
 Ul 
 
 FIG. ii b. 
 
 jects, which may be provided with a stop-cock but it will 
 be seen from one of the figures that this is not necessary. 
 
48 ANALYTIC OPERATIONS. 
 
 A number of tubes similar in size and quality of glass to 
 the graduated tube, but marked only at 50 c.c., should 
 be provided. The distillates from the water are placed 
 in the ungraduated tubes, and compared with the tints 
 of the standard ammonium solution, by making the 
 volume of the latter in the graduated tube increase or 
 decrease by means of the stop-cock on the burette and 
 changing the height of the latter. 
 
 TOTAL ORGANIC NITROGEN. 
 
 Several processes for the determination of the organic 
 nitrogen in water, based on those in use in ordinary organic 
 analysis, have been devised. That of Frankland and Arm- 
 strong requires complex and extensive apparatus and 
 special skill, has been shown also to be liable to inaccuracies, 
 and has not come into extended use. 
 
 The ease and certainty with which the nitrogen of most 
 organic bodies may be converted into ammonium sulfate 
 by boiling with sulfuric acid, offers a means of determina- 
 tion free from the objections of former methods. The 
 method introduced by Kjeldahl for general organic analysis 
 was first successfully applied to water analysis by Drown 
 and Martin. 
 
 In their original process, 500 c.c. was concentrated to 
 about 300 c.c., and the distillate nesslerized for determin- 
 ing the nitrogen existing as ammonium compounds. The 
 organic nitrogen is then determined in the residual water. 
 Owing to the fact that organic matter may be decomposed 
 by moderate heat, there is liability to underestimation of 
 the nitrogen. It is best, therefore, to determine at once 
 the total unoxidized nitrogen, and estimate, without dis- 
 
SANITARY EXAMINATIONS. 49 
 
 tillation, on a separate portion of the sample, the nitrogen 
 that exists in ammonium compounds. The procedure 
 is as follows : 
 Reagents Required : 
 
 Concentrated Suljuric Acid. This should be as free as 
 possible from nitrogen. It can now be obtained of high 
 purity. 
 
 Sodium Hydroxid Solution. The white granulated 
 caustic soda sold for household use will answer; 350 grams 
 are dissolved in water and made up to 1000 c.c. 
 
 Sodium Carbonate and Hydroxid Solution. Twenty-five 
 grams of each are dissolved in 250 c.c. of distilled water, 
 and the solution boiled down to 200 c.c. to free it from 
 ammonium. 
 Analytic Process : 
 
 Determination of Nitrogen Existing as Ammonium. Two 
 hundred c.c. of the water are placed in a stoppered bottle, 
 two c.c. each of the solutions of sodium carbonate and 
 sodium hydroxid added, the stopper inserted, the solutions 
 mixed, and allowed to stand for an hour or tw r o. A filter 
 is prepared by inserting a rather large plug of absorbent 
 cotton in a funnel. This should be washed with ammo- 
 nium-free water until the filtrate gives no color with Nessler 
 reagent. The clear portion of the sample is drawn off 
 with a pipet and run through the filter, the first portions 
 being rejected, since it is diluted by the water retained 
 in the cotton. The filtration is rapid, and when 100 c.c. 
 of the liquid have passed through it, is nesslerized. If 
 but little ammonium is present, a narrow tube about 
 60 centimeters long should be used for observing the 
 color. 
 
 D 
 
5O ANALYTIC OPERATIONS. 
 
 Estimation of the Total Organic and Ammoniacal Nitro- 
 gen. Five hundred c.c. of the water are placed in a round- 
 bottomed Bohemian glass flask, ten c.c. of concentrated 
 sulfuric acid added, and a piece of pumice-stone is heated 
 to bright redness and dropped in while hot. The liquid 
 is boiled for an hour after it is colorless, or, at least, quite 
 pale yellow. The flask is allowed to cool, and about 250 
 c.c. of ammonium-free water added. Fifty c.c. of the 
 sodium hydroxid solution should be placed in the distilling 
 apparatus, about 250 c.c. of water added, a piece of red- 
 hot pumice-stone dropped in, and the liquid distilled until 
 the distillate is free from ammonium. It is best to distil 
 until the retort contains not more than TOO c.c. The 
 sulfuric acid solution is then poured in slowly by means 
 of a funnel, the stem of which touches the side of the retort, 
 so that the two liquids do not mingle. The stopper of the 
 retort is inserted, the liquids mixed by gentle agitation, and 
 distilled. If much ammonium is present, it is advisable 
 to distil the first portion into about ten c.c. of very dilute 
 (i: 1000) sulfuric acid, a piece of glass tube being con- 
 nected to the condensing worm so that the lower end dips 
 below the surface of the liquid. The distillates are col- 
 lected and nesslerized in the usual way. 
 
 A blank experiment should be made to determine the 
 amount of ammonium in the sulfuric acid. 
 
 NITROGEN AS NITRATES. 
 
 Solutions Required: 
 
 A. H. Gill has subjected the various indirect methods 
 of estimating nitrates" to comparative examination, and 
 finds the following method satisfactory : 
 
SANITARY EXAMINATIONS. 51 
 
 Phenoldisuljonic Acid. Strong sulfuric acid and pure 
 phenol are mixed in the proportion of 37 grams of the 
 former to 3 grams of the latter, and heated for six hours 
 'in, not upon, the water-bath. The resulting compound 
 usually solidifies to a white mass on standing, but can be 
 easily liquefied on the water-bath during the evaporation 
 of the samples to be tested. 
 
 Standard Potassium Nitrate. 0.722 gram of potassium 
 nitrate, previously heated to a temperature just sufficient 
 to fuse it, are dissolved in water, and the solution made up 
 to 1000 c.c. One c.c. of this solution will contain o.oooi 
 gram of nitrogen. 
 Analytic Process : 
 
 A measured volume of the water is evaporated just to 
 dryness in a porcelain basin about six centimeters in di- 
 ameter. One c.c. of the phe^noldisulfonic acid is added and 
 thoroughly mixed with the residue by means of a glass rod. 
 The liquid is then diluted with about 25 c.c. of water, 
 ammonium hydroxid added in excess, and the solution 
 made up to 50 c.c. 
 
 The nitrate converts the phenoldisulfonic acid into 
 picric acid, which, by the action of the ammonium hy- 
 droxid, forms ammonium picrate; this imparts to the 
 solution a yellow color, the intensity of which is propor- 
 tional to the amount present. 
 
 One c.c. of the standard solution of potassium nitrate 
 is now similarly evaporated in a platinum basin, treated as 
 above, and made up to 50 c.c. The color produced is 
 compared to that given by the water, and one or the other 
 of the solutions is diluted until the tints of the two agree. 
 
 I UNIVERSITY 
 
52 ANALYTIC OPERATIONS. 
 
 The comparative volumes of the liquids furnish the neces- 
 sary data for determining the amount of nitrate. 
 
 The results obtained by this method are satisfactory. 
 Care should be taken that the same quantities of phenoldi- 
 sulfonic acid are used for the water and for the comparison 
 liquid. 
 
 With subsoil and other waters probably containing much 
 nitrates, 10 c.c. will be sufficient; but with river and spring 
 waters, 25 c.c. may be used. When the organic matter is 
 sufficient to color the residue, it will be well to purify the 
 water by addition of aluminum hydroxid and filtration, 
 before evaporating. 
 
 Chlorin interferes with the accuracy of the test, but Gill 
 finds that when not amounting to more than 20 parts per 
 million it does not impair the practical value of the results. 
 When greater than this, it is best to evaporate in vacuo 
 over sulfuric acid. If the chlorin be more than 70 parts 
 per million, it should be considerably reduced by the 
 addition of silver sulfate which has been ascertained to be 
 free from nitrates. Nitrites do not influence the reaction. 
 
 The following is the process for determining nitrogen as 
 nitrates (and nitrites) recommended by the Chemical 
 Section of the A. A. A. S. It depends upon conversion into 
 ammonium by the copper-zinc couple, and subsequent 
 nesslerizing. It is inferior to the phenoldisulfonic acid 
 method, both in convenience and accuracy, and does not 
 exclude the influence of nitrites. 
 
 Take two wide-mouth glass-stoppered bottles, each hold- 
 ing 250 c.c., and a piece of sheet zinc as long and about as 
 wide as the bottles are deep from the shoulder down ; clean 
 the zinc by dipping in dilute acid and washing with water, 
 
SANITARY EXAMINATIONS. 53 
 
 and make it into a loose coil by rolling it around a piece of 
 glass tube. Immerse it in a 1.4 to 1.8 per cent, solution 
 of copper sulfate in ammonium-free water, and leave it 
 there until its surface is well covered with a continuous 
 layer of the black copper; lift it out carefully, cover it in 
 a beaker with successive portions of ammonium-free water, 
 lifting it out and draining each time, and at once put it into 
 one of the bottles of acidified water, prepared as follows: 
 Make 500 c.c. of the water to be examined distinctly 
 acid with oxalic acid added in fine powder, with constant 
 stirring, so that it shall dissolve readily, and pour half of 
 the liquid into one of these 250 c.c. bottles, and half into 
 the other, and leave them, stoppered, in a warm place for 
 twenty-four hours. Then nesslerize both samples, decant- 
 ing off the portions, as wanted, from the precipitated earthy 
 oxalates, and using double the usual quantity of Nessler's 
 solution, since the free oxalic acid must be neutralized 
 first by the alkali of the reagent. The proportion of am- 
 monia may often be so large in the water in which the 
 reduction is made, by the copper-zinc couple, that only 
 five or ten c.c. can be taken for each test, and made up 
 to 50 c.c. by the addition of ammonium-free water. The 
 difference between the results with the two portions of 
 water gives the amount of nitrogen due to the oxidized 
 nitrogen compounds in the water examined. 
 
 NITROGEN AS NITRITES. 
 
 The following is Ilosvay's modification of Griess's test. 
 It has the advantage over the original method, that the 
 color is developed more rapidly, and the solutions are less 
 liable to change. 
 
54 ANALYTIC OPERATIONS. 
 
 Solutions Required: 
 
 i-4-amidobenzenesulfonic Acid Solution (Suljanilic Acid). 
 Dissolve 0.5 gram in 150 c.c. of diluted acetic acid, 
 sp. gr. 1.04. 
 
 a-amidonaphthalene Acetate Solution. Boil o.i -gram of 
 solid a-amidonaphthalene (-naphthylamin) in 20 c.c. of 
 water, filter the solution through a plug of washed absor- 
 bent cotton, and mix the filtrate with 180 c.c. of diluted 
 acetic acid. All water used must be free from nitrites, and 
 all vessels must be rinsed out with such water before tests 
 are applied, since appreciable quantities of nitrites may 
 be taken up from the air. 
 
 Standard Sodium Nitrite. 0.275 gram pure silver nitrite 
 is dissolved in pure water, and a dilute solution of pure 
 sodium chlorid added until the precipitate ceases to form. 
 It is then diluted with pure water to 250 c.c., and allowed 
 to stand until clear. For use 10 c.c. of this solution are 
 diluted to 100 c.c. It is to be kept in the dark. One c.c. 
 of the dilute solution is equivalent to o.ooooi gram nitrogen. 
 
 The silver nitrite is prepared thus: A hot concentrated 
 solution of silver nitrate is added to a concentrated solu- 
 tion of the purest sodium or potassium nitrite available, 
 filtered while hot, and allowed to cool. The silver nitrite 
 will separate in fine, needle-like crystals, which are freed 
 from the mother liquor by filtration by the aid of a filter 
 pump. The crystals are dissolved in the smallest possible 
 quantity of hot water, allowed to cool, and again separated 
 by means of the pump. They are then thoroughly dried 
 in the water-bath, and preserved in a tightly stoppered 
 bottle away from the light. The purity may be tested by 
 heating a weighed quantity to redness in a tared porcelain 
 
SANITARY EXAMINATIONS. 55 
 
 crucible and noting the weight of the metallic silver. One 
 hundred and fifty-four parts should leave a residue of 
 1 08 parts silver. 
 Analytic Process : 
 
 Twenty-five c.c. of the water are placed in one of the 
 color-comparison cylinders, and two c.c. each of the test 
 solutions are dropped in. It is convenient to have a pipet 
 for each solution, and to use it for no other purpose. 
 
 One c.c. of the standard nitrite solution is placed in 
 another clean cylinder, made up with nitrite-free water to 
 25 c.c. and treated with the reagents as above. 
 
 In the presence of nitrites a pink color is produced. At 
 the end of five minutes the two solutions are compared, 
 the colors equalized by diluting the darker, and the calcu- 
 lation made as explained under the estimation of nitrates. 
 
 The reactions consist in tjie conversion of the sulfanilic 
 acid into diazobenzenesulfonic anhydrid, by the nitrite 
 present; this compound is then in turn converted by the 
 amidonaphthalene into azo-a-amidonaphthalene-i-4-ben- 
 zenesulfonic acid. The last-named body gives the color 
 to the liquid. 
 
 OXYGEN-CONSUMING POWER. 
 
 All organic materials being more or less easily oxidized, 
 several methods have been suggested for determining the 
 oxygen-consuming powers of waters by treatment with 
 active oxidizing agents. These methods are, however, 
 limited in value. The organic matters in water differ 
 much in character and condition, and their oxidability is 
 subject to much variation, according to the circumstances 
 under which the test is made. Nevertheless, as a high 
 
56 ANALYTIC OPERATIONS. 
 
 oxygen-consuming power certainly indicates departure 
 from purity, some additional evidence may be obtained. 
 Potassium permanganate is especially suitable. The test is 
 usually made by introducing a known amount of the per- 
 manganate into the water, which has been rendered acid, 
 and measuring after a definite period the proportion which 
 has been decomposed. 
 
 It must not be overlooked that if a water contains nitrites, 
 ferrous compounds, or sulfur compounds other than sul- 
 fates, the proportion of oxygen consumed will be greater 
 than that required for the organic matter. It has been 
 proposed, in order to remove the nitrites before applying 
 the permanganate, to take 500 c.c. of the water, add 10 c.c. 
 of the dilute sulfuric acid, boil for twenty minutes, allow 
 to cool, and then treat with permanganate. Since, how- 
 ever, the amount of nitrites, if appreciable, can be directly 
 determined, it is more satisfactory to deduct from the 
 oxygen consumed the amount required to convert the 
 nitrites present into nitrates, and the remainder will be 
 that required for the other oxidizable ingredients. Four- 
 teen parts of nitrogen existing as nitrite require 16 parts 
 of oxygen for conversion into nitrate. Similarly, 112 
 parts of iron in a ferrous compound will require 16 parts 
 of oxygen for conversion to the ferric condition. 
 
 Of the following methods the first is due, in the main, 
 to Tidy, has been improved by Dupre, and was approved 
 by the Society of Public Analysts of Great Britain : 
 Solutions Required : 
 
 Standard Permanganate. 0.395 g ram pure potassium 
 permanganate is dissolved in distilled water, and the 
 
SANITARY EXAMINATIONS. 57 
 
 solution made up to 1000 c.c. One c.c. is equal to o.oooi 
 gram oxygen. 
 
 Diluted Suljuric Acid. Add 50 c.c. of pure sulfuric 
 acid to 100 c.c. of water, and then add solution of potas- 
 sium permanganate until a faint pink color is obtained, 
 which is permanent when the liquid is heated to 80 F. 
 for four hours. 
 
 Potassium lodid. Ten grams of the pure salt recrystal- 
 lized from alcohol are dissolved in 100 c.c. of distilled water. 
 
 Sodium Thiosuljate. One gram of the pure crystallized 
 salt dissolved in 2000 c.c. of distilled water. 
 
 Starch Indicator. One gram of clean starch is mixed 
 smoothly with cold water into a thin paste, then poured 
 gradually into about 200 c.c. of boiling water, the boiling 
 continued for one minute, the liquid allowed to- settle, and 
 the clear portion used. It js best freshly prepared. 
 Analytic Process : 
 
 Two determinations are made one, of the oxygen con- 
 sumed in fifteen minutes, which is considered to represent 
 the nitrites, sulfids, or ferrous compounds, and the other, 
 of the oxygen consumed by four hours' action. Both de- 
 terminations are made at a temperature of 80 F. Three 
 glass-stoppered bottles, of about 350 c.c. capacity, are 
 rinsed with strong sulfuric acid and then with water. In 
 one is placed 250 c.c. of pure distilled water as a control 
 experiment, and in each of the others 250 c.c. of the water 
 to be tested. The bottles are stoppered and brought to a 
 temperature of 80 F.; 10 c.c. of the dilute sulfuric acid 
 and 10 c.c. of the standard permanganate are added to 
 each, and the stoppers again replaced. At the end of 
 fifteen minutes one sample of water is removed from the 
 
58 ANALYTIC OPERATIONS. 
 
 bath, and two or three drops of the potassium iodid solu- 
 tion added to remove the pink color. After thorough 
 admixture, the thiosulfate solution is run in from a buret 
 until the yellow color is nearly destroyed, a few drops of 
 the starch solution added, and the addition of the thiosul- 
 fate continued until the blue color is quite discharged. 
 If the addition of the thiosulfate solution has been properly 
 conducted, one drop of the permanganate solution will 
 restore the blue color. 
 
 The other bottles are maintained at 80 F. for four 
 hours. Should the pink color disappear rapidly in the 
 bottle containing the water under examination, 10 c.c. of 
 the permanganate solution must be added to each bottle, 
 in order to maintain a distinct pink color. At the end of 
 four hours each bottle is removed from the bath, two 
 or three drops of potassium iodid added, and the titration 
 with thiosulfate solution conducted as just described. 
 The calculation is most conveniently made as follows: 
 
 a = number of c.c. required for the control experiment. 
 b = number of c.c. required for the water under examina- 
 tion. 
 
 c = available O in permanganate (o.ooi for 10 c.c.). 
 x = oxygen consumed by water. 
 Then, a : a-b : : c : x. 
 
 The following method was recommended by the Chemical 
 Section of the American Association for the Advancement 
 of Science: 
 
 "Prepare a solution of potassium permanganate con- 
 taining 0.2 milligram of available oxygen to i c.c. and a 
 
SANITARY EXAMINATIONS. 59 
 
 solution of oxalic acid of such strength as to decompose 
 the permanganate solution, volume for volume, the strength 
 being redetermined from time to time. The water used 
 for making. these solutions should be purified by distillation 
 from alkaline permanganate. 
 
 "To 200 c.c. of water to be examined, in a 400 c.c. flask, 
 add 10 c.c. of dilute sulfuric acid (1:3) and such measured 
 quantity of the permanganate as will give a persistent 
 color; boil ten minutes, add, if necessary, more perman- 
 ganate in measured quantities, so as to maintain the red 
 color; remove the flask from the lamp, add 10 c.c. of oxalic 
 acid solution to destroy the color, or more if required by 
 the excess of permanganate, and then add permanganate, 
 drop by drop, until a faint pink tint appears.. From the 
 total quantity of permanganate used deduct the equivalent 
 of the oxalic acid used, and, from the remainder calculate 
 the milligrams of oxygen consumed by the oxidizable 
 organic matter in the water." 
 
 The oxygen-consuming power may also be indirectly 
 estimated by the action of the organic matter upon silver 
 compounds. H. Fleck's method depends upon the reduc- 
 tion produced by boiling the water with alkaline solution 
 of silver thiosulfate and estimation of the unreduced silver. 
 A. R. Leeds has proposed a method by treating the water 
 with decinormal silver nitrate, exposing to light until it 
 settles perfectly clear, and estimating the reduced silver. 
 
 These methods are open to practically the same objec- 
 tions as in the use of permanganate, and do not seem to 
 possess any decided advantage. Qualitative results of 
 some interest may occasionally be obtained by the fol- 
 lowing method: Two c.c. of a one per cent, solution of 
 
60 ANALYTIC OPERATIONS. 
 
 silver nitrate, rendered decidedly alkaline by ammonium 
 hydroxid, are added to 100 c.c. of the water in a stoppered 
 bottle, which is then placed in full sunlight for two hours. 
 Waters containing but little organic matter will not show 
 at the end of this period any appreciable tint. 
 
 PHOSPHATES. 
 
 The following method is recommended by A. G. Wood- 
 man: 
 Solutions Required : 
 
 Ammonium Molybdate Solution. 50 grams in i liter of 
 distilled water. 
 
 Nitric acid, sp. gr. 107. 
 
 Sodium Phosphate Solution. 0.5324 gram crystallized 
 disodium hydrogen phosphate, 100 c.c. of the above nitric 
 acid, distilled water sufficient to make i liter. This is 
 equivalent to o.oooi P 2 O 5 in i c.c. 
 Analytic Process : 
 
 Fifty c.c. of the sample and 3 c.c. of nitric acid are eva- 
 porated to dryness in a porcelain dish on the water-bath, 
 the residue heated for two hours at 100 C., and treated 
 with 50 c.c. of cold distilled water added in several portions 
 which are mixed in a comparison tube. It is usually un- 
 necessary to filter. Four c.c. of the ammonium molybdate 
 solution and 2 c.c. of nitric acid are added, the contents 
 mixed, and after three minutes the color compared with 
 that given by different quantities of the standard phos- 
 phate solution which have been made up to 50 c.c. and the 
 reagents added in the same amount as above. 
 
 Blank tests must be made to determine the purity of the 
 materials used. Distilled water kept for some time in 
 
SANITARY EXAMINATIONS. 6 1 
 
 glass vessels may contain appreciable amounts of substances 
 giving color with the reagents. 
 
 Ammonium molybdate solution suitable for the gravi- 
 metric determination of phosphates may be prepared as 
 follows : 
 
 Weigh into a beaker 10 grams of pure molybdenum ter- 
 oxid, mix well with 40 c.c. cold distilled water, and add 
 8 c.c. strong ammonium hydroxid, sp. gr. 0.900. When 
 completely dissolved, filter and pour slowly, with constant 
 stirring, into a mixture of 40 c.c. of nitric acid, sp. gr. 
 1.42, and 60 c.c. of water. Add 0.005 gram sodium am- 
 monium hydrogen phosphate, dissolved in a little water, 
 agitate well, allow precipitate to settle twenty-four hours, 
 and filter before using. 
 
 DISSOLVED OXYGEN. 
 
 The method here given, a modification of Mohr's, was 
 proposed by Blarez. It is rapid and satisfactory. 
 Solutions Required : 
 
 Sodium Hydroxid. Forty grams of pure sodium hy- 
 droxid to the liter. 
 
 Ferrous-ammonium Sulfate. Forty grams dissolved- in 
 about a liter of water, and acidified with a few drops of 
 concentrated sulfuric acid. 
 
 Decinormal Potassium Permanganate. 3.156 grams dis- 
 solved in a liter of distilled water. The accuracy of this 
 solution should be determined by titration with a known 
 weight of ferrous-ammonium sulfate. One c.c. should be 
 equivalent to 0.0392 gram ferrous ammonium sulfate 
 (0.0008 gram of oxygen). 
 
62 
 
 ANALYTIC OPERATIONS. 
 
 The apparatus employed (shown in Fig. 12) is a globular 
 separator, of about 250 c.c. capacity. Above the bulb is a 
 caoutchouc stopper carrying a cylindric funnel, of about 
 12 c.c. capacity, terminating in a tube, 8 mm. caliber, 
 sharply contracted at the outlet to a capillary opening. 
 The tube should project about 6 mm. below the stopper. 
 The exact capacity of the apparatus is measured as follows : 
 The bulb is completely filled with water and the stopper 
 inserted; the level of the water will rise slightly in the 
 funnel tube, and should be brought down to its 
 outlet by drawing a little off at the stop-cock, 
 after which the water is run into a graduated 
 measure and its volume noted. 
 Analytic Process : 
 
 Thirty-five c.c. of mercury and ten c.c. of 
 sodium hydroxid solution are put into the bulb, 
 and then sufficient of the water to be tested to 
 fill it. The funnel stopper is inserted, and the 
 water which rises into the funnel brought into 
 the bulb by cautiously running out at the stop- 
 cock, mercury, the volume of which should be 
 noted. The exact volume of water used is thus 
 known. Five c.c. of the ferrous ammonium sulfate solution 
 are poured into the funnel, brought into the bulb by running 
 out mercury, and the liquid thoroughly mixed by giving the 
 apparatus a gyratory movement. After standing five or six 
 minutes, the oxygen will be completely absorbed; 10 c.c. of 
 the diluted sulfuric acid are now added by the same method. 
 On agitating the bulb, the contents become clear. The 
 watery liquid is then transferred to a beaker and titrated 
 with decinormal permanganate. A volume of water equal 
 
 FIG. 12. 
 
SANITARY EXAMINATIONS. 63 
 
 to that used in the test is poured into another beaker, 10 
 c.c. each of the sodium hydro xid and diluted sulfuric acid 
 added, and then 5 c.c. of ferrous ammonium sulfate solu- 
 tion. The resulting liquid is titrated with permanganate. 
 The weight of oxygen corresponding to the difference be- 
 tween the two titrations gives the weight of dissolved oxygen 
 in the liquid employed. 
 
 Nitrates do not appear to impair the accuracy of this 
 method, and the interfering action of nitrites and other 
 reducing compounds is avoided by the control experiment. 
 
 It is perhaps hardly necessary to add that the exact tem- 
 perature of the water is to be noted at the time of collection 
 of the sample. 
 
 In transferring to the bulb, the water should be agitated 
 as little as possible in contact with the air, in order to 
 avoid the absorption of oxygen. A siphon should be used 
 for this purpose, the lower end being allowed to reach to 
 the bottom of the bulb. 
 
 POISONOUS METALS. 
 
 Under this conventional title are included barium, 
 chromium, zinc, arsenic, copper, and lead; manganese, iron, 
 aluminum, also, though not usually classed in this group, 
 are objectionable when present in notable amounts. 
 '' Barium is rarely present, and only in water containing 
 no sulfates. It can be detected and estimated by slightly 
 acidifying the water with hydrochloric acid, filtering if 
 necessary, and addihg solution of calcium sulfate. The 
 precipitated barium sulfate is collected and weighed in 
 the usual way. 
 
 Chromium is rarely present, but may be looked for in 
 
64 ANALYTIC OPERATIONS. 
 
 the waste waters of dye-works and similar sources. To 
 detect it, a considerable volume of the water is evaporated 
 to dryness with addition of a small amount of potassium 
 chlorate and nitrate, transferred to a porcelain crucible and 
 brought to quiet fusion; any chromium present will be 
 found in the residue in the form of chromate. The fused 
 mass, after cooling, is boiled with a little water, filtered, 
 the filtrate rendered slightly acid with hydrochloric acid, 
 and a solution of hydrogen dioxid added. In the presence 
 of chromium a transient blue color will appear; by adding 
 a little ether and shaking the mixture, the color will pass 
 into the ether, and on standing will form a blue layer on the 
 surface of the water. 
 
 Zinc is best detected by the test described by Allen. 
 The water is rendered slightly alkaline by addition of 
 ammonium hydroxid, heated to boiling, filtered, and the 
 clear liquid treated with a few drops of potassium ferro- 
 cyanid; in the presence even of the merest trace of zinc 
 a white precipitate will be produced, 
 v Arsenic is most readily detected by Reinsch's test. 
 One liter of the water is rendered slightly alkaline by pure 
 sodium carbonate, and evaporated nearly to dryness in a 
 porcelain basin. Two or three c.c. of water strongly acidu- 
 lated with hydrochloric acid are placed in a small test-tube, 
 about J of a square centimeter of bright copper foil is 
 added, and the liquid boiled gently for a few moments. If 
 the copper remains bright, showing that the reagents con- 
 tain no arsenic, the water-residue is acidified with hydro- 
 chloric acid, added to the contents of the test-tube, and the 
 liquid again boiled for several minutes. If arsenic be pres- 
 ent, a steel-gray stain will appear on the copper. The slip 
 
SANITARY EXAMINATIONS. 65 
 
 is removed, washed with distilled water, thoroughly dried by 
 pressure between filter paper, inserted into a narrow glass 
 tube closed at one end, which has been previously dried by 
 heating nearly to redness. The tube is gently heated at 
 the point at which the copper rests ; the deposit will sublime 
 and collect on the cooler portion of the tube, in crystals 
 which the microscope shows to be octahedral. 
 
 Since small amounts of arsenic frequently occur in re- 
 agents and in glass vessels, care must be taken to avoid 
 such sources of error. Sodium carbonate solution may 
 contain arsenic dissolved from the glass bottle in which 
 it is kept. It is best, therefore, to use the solid carbonate 
 for rendering the water alkaline, and to determine its 
 purity before use. 
 
 / Iron is detected by the addition of a drop of ammonium 
 
 I sulfid to the water in a tall^ glass cylinder. Ferrous sul- 
 
 ( fid is formed, having a greenish-black color, instantly 
 
 , discharged by acidifying the water with dilute hydrochloric 
 
 | acid. A still better test is the production of a blood-red 
 
 ( color, with potassium thiocyanate, due to the formation 
 
 1 of ferric thiocyanate. The water should be first boiled 
 
 with a few drops of nitric acid, to convert the iron to the 
 
 1 ferric condition, cooled, and a drop or two of the solution 
 
 I of potassium thiocyanate added. The test is very delicate. 
 
 Either of the above tests may be made quantitative by 
 
 matching the color produced in 100 c.c. of the water with 
 
 that obtained from a known weight of iron. The method 
 
 with potassium thiocyanate is preferable, as it is more 
 
 delicate and there are fewer interfering conditions. The 
 
 following is the method as elaborated by Thompson and 
 
 described in Sutton's "Volumetric Analysis": 
 
66 ANALYTIC OPERATIONS. 
 
 Solutions Required: 
 
 Standard Ferric Suljate. 0.7 gram ferrous ammonium 
 sulfate is dissolved in water acidified with sulfuric acid, 
 and potassium permanganate solution added until the 
 solution turns a very faint pink color. The solution is 
 diluted to a liter. One c.c. contains o.i milligram iron. 
 
 Diluted Nitric Acid. Thirty c.c. concentrated nitric 
 acid diluted with water to about 100 c.c. 
 
 Potassium Thiocyanate. Five grams of the salt dis- 
 solved in about 100 c.c. water. 
 Analytic Process : 
 
 About 100 c.c. of the water are evaporated to small bulk, 
 acidified with hydrochloric acid,, and just sufficient dilute 
 potassium permanganate solution added to convert all the 
 iron to the ferric condition. The liquid is evaporated 
 nearly to dryness to drive off excess of acid, then diluted 
 to its original volume, 100 c.c. In two tall glasses marked 
 at 100 c.c., 5 c.c. of the nitric acid and 15 c.c. of the thio- 
 cyanate solution are placed. To one of these a measured 
 volume of the treated water is added and both vessels 
 filled up to the mark with distilled water. If iron is present, 
 a blood-red color will be produced. Standard iron solu- 
 tion is added to the second vessel until the color agrees. 
 The amount of water which is added to the first glass will 
 depend upon the quantity of iron it contains; not more 
 should be used than will require two or three c.c. of the 
 standard to match it, otherwise the color will be too deep 
 for comparison. 
 
 Manganese. The following method is described by 
 Wanklyn in his treatise on water analysis. About one liter 
 of the water is evaporated to small bulk, nearly neutralized 
 
SANITARY EXAMINATIONS. 67 
 
 by hydrochloric acid and treated with a few drops of a 
 solution of hydrogen dioxid. The formation of a brown 
 precipitate indicates the presence of manganese. The test 
 is very delicate. The precipitate may be collected on 
 a filter, the filter ashed, and the residue fused with a mix- 
 ture of sodium carbonate and potassium nitrate. Green 
 potassium manganate will be produced, which, when boiled 
 with water, will give a bright-red solution of potassium 
 permanganate. The quantitative determination is given 
 elsewhere. 
 
 Aluminum. Traces of this element are to be ex- 
 pected in all waters, and it is not usual to test for it except 
 in elaborate analysis of the mineral ingredients, as de- 
 scribed in another section. The use of aluminum sulfate 
 as a coagulant in many rapid-filtration methods makes it 
 necessary to examine effluen-ts for excess of precipitant, and 
 this may be done by the following method devised by 
 Mrs. Richards: 
 
 To 25 c.c. of the water to be tested (concentrated from 
 one liter or more, if necessary) is added a few drops of 
 freshly prepared logwood decoction; any alkali is neutral- 
 ized and the color is brightened by the addition of two 
 or three drops of acetic acid. By comparison with standard 
 solutions, the amount of alum present may be determined. 
 One part of alum in 1,000,000 of water can be detected 
 with certainty. In cases of greater dilution, concentration 
 of several liters may be necessary to obtain a decisive 
 test. The logwood chips yield the right color only after 
 having been treated with boiling water two or three times, 
 rejecting the successive decoctions. The first portion gives 
 a yellow color, the third or fourth usually a deep red. The 
 logwood chips must be fresh. 
 
68 ANALYTIC OPERATIONS. 
 
 f Lead may be readily detected by adding to the water in 
 ' a tall glass cylinder a drop of ammonium sulfid; brown - 
 ( ish-black lead sulfid is formed, which does not dissolve 
 ( either by acidulating the water with dilute hydrochloric 
 '. acid (distinction from iron), nor by the addition of about 
 ' one c.c. of a strong solution of potassium cyanid (distinction 
 ' from copper). S. Harvey gives the following method: 
 250 c.c. are placed in a precipitating jar, about o.i gram 
 of crystallized potassium dichromate is added and dis- 
 solved by agitation. The same volume of lead-free water 
 is treated in the same manner, and the two solutions placed 
 side by side. Water containing 0.3 part per million will 
 show a turbidity in fifteen minutes which will be rendered 
 more distinct by contrast with the clear water alongside. 
 By allowing the jar to stand for about twelve hours un- 
 disturbed, the precipitate will settle and will become still 
 more distinct. No other metal likely to be present in 
 water will give a similar reaction. 
 
 In the absence of copper the amount of lead present may 
 be determined as follows : A solution is prepared containing 
 1.6 grams of lead nitrate to the liter; one c.c. of this contains 
 one milligram lead. One hundred c.c. of the water to be 
 tested are placed in a tall glass vessel, made acid by the 
 addition of a few drops of acetic acid, and five c.c. of hy- 
 drogen sulfid added. In a similar vessel 100 c.c. of dis- 
 tilled water are placed, together with the same quantities of 
 acetic acid and hydrogen sulfid, and sufficient of the stan- 
 dard lead solution to match the tint in the first cylinder. 
 The amount of lead in the water under examination is thus 
 known. 
 
 Copper is detected in the same manner as lead by acidify- 
 
SANITARY EXAMINATIONS. 69 
 
 ing the water with acetic acid and adding hydrogen sulfid. 
 The precipitate is distinguished from lead sulfid by the 
 fact that the color is discharged on the addition of about 
 i c.c. of a strong solution of pure potassium cyanid. It 
 may be further confirmed by the addition to another por- 
 tion of the water of a solution of potassium ferrocyanid. 
 In the presence of even a very small amount of copper, a 
 mahogany-red color is produced. 
 
 In the absence of lead, copper is estimated in the same 
 way as that metal, using, however, a standard solution of 
 copper for the comparison liquid. This is made by dis- 
 solving 3.929 grams of crystallized copper sulfate in one 
 liter of water. One c.c. of the solution contains one milli- 
 gram copper. 
 
 If both lead and copper are present, a large quantity of 
 the water should be evaporated to small bulk, and the 
 metals separated and estimated by any one of the ordinary 
 laboratory methods. 
 
 BIOLOGIC EXAMINATIONS. 
 
 In a comprehensive sense the living organisms of water 
 include representatives of all the great groups of animals 
 and plants. The higher orders of organic forms are absent 
 from very foul water. From an analytic point of view, 
 observation is limited to the determinations of those forms 
 which are inappreciable to the unassisted eye. So far as 
 regards some of the moderately complex organisms, such 
 as the minute crustaceans, algae, desmids, and even the 
 amebse, it may be said that while some general inferences 
 as to the character and history of the water may be deduced 
 from an identification of the specific forms, no definite 
 
70 ANALYTIC OPERATIONS. 
 
 sanitary signification can be attached to them. From 
 what is now known of the life-history of many parasitic' 
 organisms, it is evident that water that is freely accessible 
 to any animal forms is liable to be dangerously polluted. 
 Moreover, the dead bodies of such animals will furnish 
 food to many forms of microbes and thus assist in the 
 multiplication of the latter. The ova of the entozoa might 
 in some cases be detected by careful search, and would 
 indicate recent pollution of a highly dangerous character 
 
 The number of the higher forms present in any sample 
 will depend very much upon the point at which it is col- 
 lected, they being more numerous in the neighborhood of 
 large plants and at the bottom and sides of streams. 
 
 Several observers, notably Sedgwick and Rafter, have 
 paid considerable attention to the recognition of the animal 
 and vegetable forms in surface waters. Some of these 
 forms cause disagreeable odors and colors; in the warm 
 season of the year, when such water is stored in reservoirs, 
 considerable annoyance is felt by the users, and the 
 engineer-in-charge is subjected to much criticism. It has 
 been found that even crude nitration methods, such as allow- 
 ing the water to pass through a dike of porous soil before 
 storing it in a reservoir, will diminish the tendency to these 
 conditions. Cleansing a reservoir, disinfecting the inner 
 surface, for instance, by whitewashing, has also improved 
 the condition. 
 
 Observation, especially in Massachusetts, has shown 
 that reservoirs intended for even moderately prolonged 
 storage of water should be clean that is,, organic matter 
 of any kind should not be allowed to accumulate on the 
 bottom and sides. Drown states that while the water in 
 
SANITARY EXAMINATIONS. 7 1 
 
 one basin became foul from stagnation, in another which 
 was carefully prepared by the removal of all soil and vege- 
 table matter, and is supplied by a brown, swampy water 
 from a district almost entirely free from pollution, the 
 water is good at a depth of forty feet. 
 
 In Philadelphia, where large storage reservoirs are used 
 for water that is often very muddy, but little trouble from 
 the growth of microscopic organisms occurs. These reser- 
 voirs are artificial basins. 
 
 Sedgwick's method of collecting organisms other than 
 microbes, with some modifications by Williston, is as 
 follows : 
 
 In ordinary cases about 100 c.c. are employed. Some- 
 times it will be advantageous to use double this quantity, 
 at other times much less. In rare cases the examination 
 can be made upon unfiltere/l water. Originally sand was 
 employed for a filter material, but Williston finds that 
 precipitated silica, made by decomposing silicon fluorid 
 with water, is more satisfactory. This precipitated silica 
 is a commercial article, and its method of preparation is 
 given in all the larger manuals of chemistry. 
 
 A small glass funnel with an even-calibered stem is 
 selected, and the lower end of the stem plugged with a 
 little absorbent cotton, upon which a layer three or four 
 mm. deep of the filter-material is placed. The requisite 
 volume of water is then allowed to filter through. The 
 pledget of cotton is removed, and the filter-material is 
 washed down with filtered or distilled water into a cell 
 intended for microscopic examination. This cell is a glass 
 plate accurately ruled, to which is attached a brass cell 50 
 mm. long by 10 mm. wide, of depth sufficient to hold 
 
72 ANALYTIC OPERATIONS. 
 
 about two c.c. of water. After the material has been 
 allowed to distribute itself and settle in the cell, it is ex- 
 amined with a moderate power, and the different organisms 
 in a varying number of the squares counted. Each or- 
 ganism may be counted by itself, if occurring in large 
 numbers, the average of a few squares being sufficient for 
 the purpose. Organisms less numerously represented may 
 be counted by averaging a larger number of squares. 
 
 Filtering in this manner can not be relied upon in all 
 cases. Indeed, in most cases the unfiltered water also 
 should be examined. Some of the minute unicellular 
 organisms pass readily through the small extent of sand or 
 precipitated silica, or even through filter-paper. 
 
 It is not unlikely that the high-speed centrifugal appara- 
 tus now used in laboratories, associated with the employ- 
 ment of some fine precipitant, will aid in these investiga- 
 tions. 
 
 Dibdin prepares as follows, a "micro-filter," for the 
 collection of minute suspended matters: A piece of com- 
 bustion-tubing 20 to 25 cm. long is cleaned and drawn 
 out in the middle to a capillary tube, and broken by a 
 file scratch at a point at which the caliber is not more than 
 two millimeters. Each of these pieces serves for a filter. 
 A mixture of equal parts of air-dried clay and infusorial 
 earth is made into a smooth, stiff paste with water and 
 spread out on a slab in a layer about two millimeters deep. 
 The capillary end of a tube is pressed down into the mass 
 and moved in a circle until a plug is formed. This is 
 warmed until dry, and heated to redness, forming a close 
 filter. 
 
 The water to be examined is filtered in considerable 
 
SANITARY EXAMINATIONS. 73 
 
 amount, one liter, for example, if there is but little sus- 
 pended matter, first through a hardened paper filter placed 
 in a funnel, precautions being taken to exclude dust. The 
 deposit is washed from the filter paper into the micro- 
 filter by means of a jet of pure water. The suspended 
 matter collects on the top of the clay plug and is measured 
 by noting its height. If the clay plug is blocked the ap- 
 plication of a filter-pump may be needed. When the column 
 of water in the small tube is only about a centimeter in 
 height, the main body of the tube is cut away by means of 
 a file scratch and the deposit loosened from the filter plug, 
 if necessary, by the use of a platinum wire. The tube is 
 inverted so as to bring the deposit to the open end, and 
 then cut off close to the plug. By this means the sus- 
 pended matter is collected in a short capillary tube open 
 at both ends. By gentle ^haking, the contents may be 
 brought onto a glass slide. 
 
 Owing to the great differences in the size of microscopic 
 organisms, the mere enumeration of their numbers is not 
 always an index of the amount of living matter in sus- 
 pension. To obviate this, Whipple has suggested a stan- 
 dard unit of size, estimating by means of it the total volume 
 of the organisms, and not their number. He finds by 
 this method that the analytic and biologic results corre- 
 spond much more closely than when mere numbers are 
 recorded. The unit is an area of 400 microns that is, 
 a square of 20 microns on a side. The results are stated 
 in number of standard units per cubic centimeter. 
 
 Mr. Whipple has investigated the conditions influencing 
 the growth of the microscopic organisms in water. He 
 finds that diatoms thrive best with a supply of nitrates and 
 
74 ANALYTIC OPERATIONS. 
 
 a free circulation of air; temperature alone has no very 
 direct effect. Infusoria will be found in largest numbers 
 when the water contains the greatest amount of finely 
 divided organic matter. When the conditions bring about 
 a circulation of the water, the organisms are not only 
 brought constantly in contact with new food materials, 
 but are enabled to reach the upper layers of the water where 
 oxygen is abundant. 
 
 Bacteriologic examinations may be qualitative or 
 quantitative. The former involves the determination of 
 the species of microbes present, especially those having 
 disease-producing power, or characteristic of some form of 
 pollution. The processes are usually laborious, requiring 
 extensive laboratory facilities. Quantitative examination 
 microbe-counting, as it may be called is the determination 
 of the number of microbes, or microbe-colonies, that can 
 be grown from a given volume of water under specified 
 conditions. As the growth of living organisms is influenced 
 by all external conditions, the results of the culture of 
 microbes are not comparable with one another, unless 
 strict uniformity of methods has been observed. Neglect 
 of this fact renders a very large part of the earlier \vork and 
 some of the present-day work of little statistical value. 
 Among the conditions materially affecting the growth of 
 microbes are temperature, reaction of the culture-medium 
 to different indicators, degree of exposure to light and air, 
 and duration of cultivation. The composition of the 
 culture-medium has much influence, and it is difficult to 
 control this exactly, owing to the irregularity of quality 
 of some of the materials used. 
 
 At the present day, microbe-counting for water analysis 
 
SANITARY EXAMINATIONS. 75 
 
 is done almost entirely with culture-media that are solid 
 at ordinary temperatures but may be liquefied at or near 
 blood-heat. Gelatin or agar is used for producing the 
 solidity. The former is the most convenient, but its jelly 
 melts at such a low temperature that it is of limited ap- 
 plication, and agar is largely employed. 
 
 Apparatus for bacteriologic work is now all furnished 
 of good quality by dealers, and will not need special de- 
 scription. For the ordinary methods of microbe-counting 
 the following will be needed : 
 
 Open-steam Sterilizer. A modification of the Arnold 
 sterilizer is now much used. 
 
 Autoclave, a closed-steam sterilizer, permitting the ap- 
 plication of temperatures much above the boiling point of 
 water. 
 
 Hot Air Oven for special /sterilizations. 
 
 Culture Oven, with thermostat. 
 
 Double Boiler of agate or other good culinary ware. 
 The inner vessel should have a capacity of a little more 
 than a liter. 
 
 Test-tubes, about 12 cm. long and 1.5 cm. in diameter. 
 
 Petri dishes, about 10 cm. in diameter and i.o cm. deep. 
 As far as possible, dishes of uniform size should be selected. 
 Each dish and cover should be marked in the center by a 
 diamond with a distinguishing number. 
 
 Wire baskets for holding several dozen test-tubes. 
 
 Fermentation-tube, such as used in the detection of sugar 
 in urine. 
 
 Ordinary laboratory appliances, such as pipets, burets, 
 funnels, beakers, and cotton-wool. Tin-foil cut in squares 
 5 cm. on the side. 
 
76 ANALYTIC OPERATIONS. 
 
 The materials for preparing culture-media should be 
 obtained from responsible dealers, who will furnish the 
 grades regularly used. The following will assist in the 
 selection. 
 
 Gelatin. A grade made in Germany and distinguished 
 by a monogram of the initials WH is used. 
 
 A gar. A colorless grade is preferable. 
 
 Peptone. Witte's dry peptone is used. 
 
 Glucose. The grade termed "crystallized pure" is 
 preferred; it consists principally of dextrose. 
 
 Meat-extract. That made by the Liebig Meat-Extract 
 Company, limited, of London, is almost the only form 
 used by bacteriologists, but there seems to be no reason 
 for preference to some of the American extracts. 
 
 Sodium chlorid. A good quality of table salt will suffice. 
 
 Glycerol should be as free as possible from acid and 
 mineral matters. 
 
 Lactose should be of high purity, especially free from 
 milk-proteids. 
 Preparation of Culture-media : 
 
 Bouillon is the term applied to many forms of liquid 
 media, prepared with meat juice or meat-extract. The 
 ordinary bouillon is prepared according to the following 
 formula : 
 
 Five hundred grams of finely-chopped meat, as free as 
 possible from fat and gristle, are soaked overnight in about 
 a liter of cold water, at a temperature between o C. and 
 10 C. The mass is then strained through a coarse towel and 
 pressed until as much as possible of the liquid is obtained. 
 To this is added 10 grams of peptone and 5 grams of com- 
 mon salt. It is then heated to boiling, best in the open- 
 
SANITARY EXAMINATIONS. 77 
 
 steam sterilizer, to coagulate albumin, after which it is 
 filtered. The most difficult point in the work is neu- 
 tralization. This is often accomplished by the use of 
 sodium carbonate, which is added in small amounts until 
 the liquid no longer affects red litmus paper. The better 
 method is to titrate a portion of the bouillon with sodium 
 hydro xid solution, and calculate from this the amount 
 of that solution necessary to neutralize the whole of the 
 liquid. Fuller has devised a good method of procedure. 
 The bouillon is made up when cool to a definite volume, 
 say 1000 c.c.; 5 c.c. are mixed with 45 c.c. of distilled water 
 in a porcelain dish, boiled for three minutes, i c.c. of solu- 
 tion of phenolphthalein added, and quickly titrated with 
 twentieth normal sodium hydroxid. The neutral point 
 is the slight pink color not disappearing on gentle stirring. 
 From the number of cubic, centimeters used the amount 
 of alkali needed to neutralize the whole solution is cal- 
 culated, but this alkali should be added in the form of 
 normal solution in order to avoid much dilution of the 
 bouillon. 
 
 Bouillon may be modified in many ways, by the ad- 
 dition of different substances, but the inherent or possible 
 acidity or alkalinity of these must be ascertained and 
 corrected if culture results are to be kept standard. 
 
 A dextrose bouillon for special fermentation work is 
 made by adding glucose in the proportion of 20 grams 
 to 1000 c.c. of the liquid. 
 
 Meat-extract is often used instead of the infusion of 
 chopped meat. Five grams of a good commercial extract 
 are used for each 1000 c.c. of bouillon. 
 
 Gelatin Media. The ingredients, other than the gelatin, 
 
78 ANALYTIC OPERATIONS. 
 
 are dissolved and treated as described in the making 
 of bouillon. After neutralization, the gelatin is dissolved 
 by gentle heating. If this contributes any acidity, it must 
 be neutralized. The heating may be done in the double 
 boiler. The liquid should not be heated strongly or for a 
 long time, as the gelatinizing property may be injured. 
 The solution is made up to the proper volume and filtered 
 through paper. 
 
 Meat-extract peptone- gelatin. 
 
 Meat-extract, - 5.0 grams 
 
 Peptone, 10.0 " 
 
 Gelatin, 150.0 " 
 
 Dextrose, 2.0 " 
 
 Sodium chlorid, 5.0 " 
 
 Water, 1000.0 c.c. 
 
 The preparation of agar solution is more difficult than 
 that of gelatin. Several methods have been suggested. 
 Ravenel uses high pressure, according to the following 
 methods : 
 
 Preferable Method: 
 
 (A) Chopped meat, 500 grams 
 
 Water, 500 c.c. 
 
 These are mixed and allowed to stand overnight. 
 
 (B) Agar, 12 grams 
 
 Water, 500 c.c. 
 
 Solution B is put into the autoclave, the pressure run up 
 to 2 atmospheres, the heat withdrawn, and the boiler 
 opened when the temperature has fallen a little below 
 100 C. The solution is allowed to cool to about 75 C. 
 (below the coagulating point of albumin), 10 grams of 
 
SANITARY EXAMINATIONS. 79 
 
 dried peptone and 5 grams of sodium chlorid are added, 
 A and B mixed, the liquid boiled for about three minutes, 
 neutralized and filtered. The filtration is very quick 
 from ten to twelve minutes for a liter. A hot-water funnel 
 is not needed, but the filter must be moistened with boiling 
 water immediately before pouring in the agar. In the pro- 
 cess with fresh meat the clarification is effected by the 
 coagulation of the albumin in the meat-water, hence solu- 
 tion B must not be added to A until cool enough to avoid 
 coagulation. 
 Alternative method: 
 
 (A) Dried peptone, 10 grams 
 
 Common salt, 5 " 
 
 Meat-extract, 5 " 
 
 Water, 500 c.c. 
 
 Boil for three minutes and neutralize. 
 
 (B) Agar-agar, 12 grams 
 
 Water, 500 c.c. 
 
 The agar is chopped fine and heated in the autoclave 
 to two atmospheres. As soon as this pressure is reached, 
 the heat is withdrawn and the liquid allowed to cool until 
 below 100 C. before opening. The two solutions A and 
 B are then mixed, cooled to 60 C., the whites of two eggs 
 beaten in 50 c.c. of water added, well stirred in, and the 
 whole then boiled and filtered through paper. 
 
 Instead of the white of egg, blood-serum may be used, 
 which seems to add also to the nutritive value of the medium. 
 Agar made with meat-extract will often form a precipitate 
 during the sterilization. 
 
 Abbott gives the following method of preparing agar 
 solution: The bouillon is prepared and neutralized in 
 
8o ANALYTIC OPERATIONS. 
 
 the usual way, then 15 grams of finely chopped agar are 
 added, and water sufficient to make the volume 1250 c.c. 
 The mass is boiled gently over a direct flame, stirring 
 occasionally, for several hours. If the fluid goes below the 
 liter level, enough water should be added to make up the 
 amount. The boiling should be continued until about 
 a liter is left in the vessel. When the solution of the agar 
 is attained, the vessel is placed in a large dish of cold water, 
 until it has cooled to about 70 C., the white of one egg 
 that has been beaten up with water added, mixed well, 
 and boiled again for a half-hour, avoiding the evaporation 
 of the liquid below the liter point. The liquid is filtered 
 through heavy folded filter paper at room-temperature. 
 It is necessary that the solution should be not above 70 C. 
 when the white of egg is added or it will become lumpy. 
 Commercial egg-albumin in 10 per cent, solution in water 
 may be used instead of white of egg. The solution thus 
 prepared should filter rapidly. 
 
 Potato Culture. Cultivation on potatoes has been much 
 used as a method of distinguishing certain microbes. 
 Large, sound potatoes should be selected, thoroughly 
 washed, and cut into disks about five centimeters in diam- 
 eter and one centimeter thick. These are placed in glass 
 boxes (pomade boxes) which have lids with ground joint, 
 and heated for about one-half hour in the sterilizer. An- 
 other method is to cut out cylinders with the aid of an 
 apple-corer, or largest size cork-borer, slice these obliquely, 
 and place them in test-tubes, which are then closed with 
 cotton plugs and sterilized. The latter method does not 
 give a large surface, but the growth of any inoculation 
 may be easily watched. 
 
SANITARY EXAMINATIONS. 8 1 
 
 Many special forms of culture-media are employed for 
 bacteriologic investigations which do not come within the 
 line of water analysis, and need not be described. One 
 form is much employed in the search for the specific germ 
 of typhoid fever, namely, Wiirtz's litmus -lactose solution. 
 This may be with either agar or gelatin, in conjunction 
 with meat extract. The nutrient medium must be made 
 so as to possess such a degree of alkalinity that 10 c.c. 
 will neutralize 0.5 c.c. of decinormal sulfuric acid. Lactose 
 is added in the proportion of two or three grams to 100 c.c. 
 of medium and the mixture sterilized, after which sufficient 
 sterilized litmus tincture is added to give the fluid a dis- 
 tinct but not deep-blue color. 
 
 Cultivation in gelatin at ordinary temperatures usually 
 yields a larger number of points of microbic life than in 
 agar at blood-heat. This js due to the fact that many 
 common water-bacteria do not grow well at the higher 
 temperatures. 
 
 Culture-media when ready for use are distributed in 
 test-tubes. These must be well cleaned. In laboratories 
 in which regular chemical work is done the solution of 
 crude chromic and sulfuric acids used for voltaic batteries 
 is a good cleaning agent, the tubes being soaked in this 
 for about a day, and then rinsed thoroughly and sterilized 
 as noted below. In bacteriologic laboratories it is usual 
 to cleanse the tubes with a 3 per cent, solution of sodium 
 hydro xid. The tubes are boiled in the solution, rinsed, 
 swabbed out with a brush, and allowed to dry in the inverted 
 position. A cotton-wool plug is made for each tube, care 
 being taken that it fits neatly, without creases or channels 
 and not too tightly. The projecting part of the plug is 
 
82 ANALYTIC OPERATIONS. 
 
 clipped moderately close and a tinfoil cap placed on each. 
 The arrangement is sterilized in the hot-air oven' at 150 C. 
 When cold, the tinfoil and plug are carefully removed, 
 about 10 c.c. of culture-medium put into each tube, with 
 as little outside contamination as possible, the plug and 
 cap replaced, and the tubes and contents sterilized in the 
 open-steam sterilizer. The wire baskets are used to hold 
 the tubes during the sterilizations. 
 
 For making cultures definite volumes of the water sample 
 are introduced into the culture-medium, and if this is a 
 solidifying form, it is put into the Petri dish. All the 
 manipulations must be conducted with great care to avoid 
 contamination. When there is no clue to the amount 
 of microbes present, it will be necessary to make cultures 
 with different proportions of water. Some tubes may be 
 inoculated with a few drops, some with three to five drops, 
 and some with i c.c. Some operators dilute the water 
 considerably and take small measured volumes. If this 
 method is used, the diluting water must be distilled and 
 have been well sterilized, by at least five minutes' boiling, 
 and cooled out of contact of air. All pipets, dishes, and 
 other apparatus that come in contact with the water must 
 have been first sterilized. 
 
 The test-tubes containing the culture-medium are 
 warmed gently, just enough to render the culture-medium 
 fluid, the desired volume of the water added, the mixture 
 shaken and promptly poured into the Petri dishes, covered 
 and placed in the oven, which should have been already 
 raised to the temperature at which it is desired to conduct 
 the work. Unless specially desired otherwise, cultures 
 should be made in the dark. They may be made at any 
 
SANITARY EXAMINATIONS. 83 
 
 temperature short of that at which the medium melts, but 
 either ordinary temperature or 37 C. is usually selected. 
 The condition of the plates should be observed at intervals 
 of twenty-four hours, and the points of microbic life 
 counted and recorded. After some days the growth will 
 become so luxuriant or the liquefaction of the medium so 
 extensive that accurate observation is not possible. 
 
 If the microbic points are numerous, it will be necessary 
 to employ a counting scale. For the Petri dish, Pake's 
 modification of Lafar's scale is cheap and sufficient. 
 
 General Character of the Microbes in Natural 
 Waters. The microorganisms of natural waters are prin- 
 cipally included in the genera Bacillus and Spirillum, 
 especially the former. Micrococci and molds are rare, 
 and are generally due to contamination by dust. 
 
 Microbes are distinguished according to the conditions 
 favorable to their growth, as follows: 
 
 Saprophytic. Growing on dead matter. 
 
 Parasitic. Growing only on living matter. 
 
 Aerobic. Requiring free oxygen. 
 
 Anaerobic. Not requiring free oxygen. 
 
 When the organism possesses the power of adapting 
 itself to different conditions, the term facultative is applied; 
 when it can grow only under special conditions, the term 
 obligatory is applied. 
 
 Microbes are also differentiated by the effect which they 
 produce upon the culture-medium. Some species rapidly 
 or slowly liquefy the jelly with evolution of foul-smelling 
 gases; others chromogenic microbes produce character- 
 istic colors. Many do not produce any positive modifica- 
 tion, and for purposes of distinction it is usual to transfer 
 
84 ANALYTIC OPERATIONS. 
 
 portions of the colonies to other culture-media. Such 
 special cultures are obtained by taking up a portion of 
 the colony on the end of a wire which has been just ster- 
 ilized by heating to redness and inoculating the prepared 
 medium. 
 
 Indol Reaction. Indol, C 8 H 7 N, more properly indin, 
 is a weak base, which is a product of the growth of many 
 species of microbes, and the detection of it may, therefore, 
 be utilized as a differentiation test. Kitasato gives the 
 following method for performing the test: 
 
 Ten c.c. of an alkaline-peptone-meat infusion (without 
 gelatin), which has been previously inoculated with the 
 microbes to be tested, and kept for twenty-four hours at 
 blood-heat, are treated with i c.c. of solution of pure 
 potassium nitrite (0.02 gram in 100 c.c.) and then with 
 a few drops of concentrated sulfuric acid. In the presence 
 of indol a rose or deep-red color is developed. Spirillum 
 cJwlercB and Bacillus coli communis give the reaction strongly; 
 S. Finkleri feebly; the so-called B. typhosus ordinarily 
 does not give it. 
 
 Careful and experienced bacteriologists do not now claim 
 to be able to isolate the typhoid bacillus from natural 
 waters. The effort has failed even with waters that are 
 obviously polluted. In default of a method for such de- 
 tection, resort is had to methods for the detection of the 
 microbe known as Bacillus coli communis. This being 
 a constant inhabitant of the intestinal canal of the highest 
 animals, and being almost always associated with dangerous 
 pollution, the detection of it in water indicates previous 
 contamination. This organism is not constant in character, 
 but, in common with many other dangerous microbes, 
 
SANITARY EXAMINATIONS. 85 
 
 grows well at blood-heat, while many common water, air, 
 and soil organisms do not. Some mild germicides also 
 affect the latter class of microbes more than the intestinal 
 bacilli. Upon these principles have been founded many 
 methods for differentiation, two of which are in common use. 
 
 The Franklands, after reviewing at length the various 
 methods that have been suggested for differentiating the 
 typhoid bacillus, show that most of them are quite insuffi- 
 cient. A routine treatment is, however, suggested as fol- 
 lows: 
 
 The water is freed from the ordinary water-bacteria 
 by preliminary culture in Parietti's solution. This is a 
 phenol-broth prepared by mixing 10 c.c. of neutral bouillon 
 with 0.25 c.c. of the following solution: 
 
 Phenol, 5 grams 
 
 Hydrochloric acid, '_ 4 " 
 
 Water, 100 " 
 
 This solution is sterilized by heating it for twenty-four 
 hours at 37 C. The tubes are then inoculated with from 
 one to ten drops of the water sample, which must be thor- 
 oughly mixed with the broth, and again kept in the sterilizer 
 for not less than forty-eight hours. If any of the tubes 
 appear turbid after the treatment they should be submitted 
 to plate cultivation, and any colonies which resemble those 
 produced by the typhoid bacillus should be further studied 
 by inoculation into gelatin tubes to observe the gas-pro- 
 ducing test, into milk to note if coagulation occurs, and 
 by cultivation in broth to determine if indol-reaction will 
 be obtained. 
 
 The method of Theobald Smith is to cultivate the water 
 
86 ANALYTIC OPERATIONS. 
 
 sample at blood-heat with a bouillon rich in dextrose and 
 note whether there is evolution of gas. The fermentation 
 tube is used. Sufficient bouillon is put in to fill the upright 
 stem and the curved part, but not much of the bulb. The 
 whole is then well sterilized in the open steam sterilizer, a 
 cotton plug with tinfoil cover having been previously placed 
 in the opening of the bulb. The apparatus is cooled ; a few 
 drops of the water sample are then introduced into the 
 bouillon, taking care not to allow outside contamination, 
 the plug and tinfoil are replaced, and the tube kept at 37 C. 
 for about forty hours. An accumulation of gas at the top 
 of the tube indicates that microbes of the type of the B. 
 coli communis are present. Several tubes and one or two 
 control tubes, that is, tubes which are not inoculated with 
 water, should be tried together. Portions of the gas-pro- 
 ducing bouillon may be inoculated into sterile agar and 
 cultivated at the same temperature after pouring into the 
 Petri dish. 
 
 The bouillon is made according to the procedure on 
 page 76, except that 20 grams of glucose are used to the 
 liter. 
 
 The resemblance between the two forms, B. typhosits 
 and B. coli communis, is so great, and the variability of 
 both forms so marked, that some observers have suggested 
 that they are but varieties of the same specific bacillus. 
 Much attention has been paid to the distinctions. The 
 following synopsis has been given by Abbott: 
 
TECHNIC EXAMINATIONS. 87 
 
 CHARACTERISTICS. B. TYPHOSUS. B. COLI COMMUNIS. 
 
 Motility, Conspicuous. Not marked. 
 
 Growth in gelatin, ___Slow. Not very slow. 
 
 " " potato, Usually inconspicu- Always rapid and visi- 
 
 ous. ble. 
 
 " " milk, No coagulation; no Acidity and coagula- 
 
 acidity. tions in forty-eight 
 
 hours in incubator at 
 38 C. 
 
 Growth in media con- 
 taining glucose, lac- 
 tose, or sucrose, No evolution of gas. Marked evolution of 
 
 gas. 
 
 Growth in media con- 
 taining lactose and 
 
 litmus, Colonies pale blue; no Colonies pink; sur- 
 
 reddening of sur- rounding medium 
 rounding medium. red. 
 Indol reaction in pep- / 
 
 tone solution (forty- 
 eight hours at 38 C.) Rarely present. Always present. 
 
 It will be seen that the characteristics of B. typhosus are 
 rather negative than positive. The data are derived from 
 cultures obtained from intestinal discharges or viscera of 
 patients affected with typical typhoid fever. 
 
 TECHNIC EXAMINATIONS. 
 GENERAL QUANTITATIVE ANALYSIS. 
 
 Silica, Iron, Aluminum, Manganese, Calcium, and 
 Magnesium. One liter of the water acidified with hy- 
 drochloric acid is evaporated to complete dryness, best 
 in a platinum dish, the residue treated with hydrochloric 
 
ANALYTIC OPERATIONS. 
 
 acid and water, and the separated silica filtered, washed, 
 dried, ignited in a platinum crucible, and weighed. 
 
 To the filtrate, previously boiled with a few drops of 
 strong nitric acid, slight excess of ammonium hydroxid is 
 added, the liquid boiled several minutes, the precipitate 
 collected, washed thoroughly with boiling water, dried, 
 ignited, and weighed. It consists of Fe 2 O 3 and A1 2 O 3 . 
 It also contains all the phosphates and some manganese if 
 much is present in the water. In such cases the precipitate 
 before drying is redissolved in hydrochloric acid and 
 neutralized with a dilute solution of ammonium carbonate 
 until the water becomes almost turbid. It is then boiled, 
 and the precipitate, now free from manganese, washed, 
 dried, ignited, and weighed. The iron may be determined 
 by dissolving the precipitate in strong hydrochloric acid 
 and employing the colorimetric method described on page 
 66. 
 
 If no manganese or only traces are present, the filtrate 
 from the iron is mixed with sufficient ammonium chlorid 
 to prevent the precipitation of the magnesium, ammonium 
 hydroxid, and then ammonium oxalate added in quantity 
 sufficient to precipitate the calcium and to convert all the 
 magnesium into oxalate, and thus hold it in solution. The 
 precipitate contains all the calcium and some of the magne- 
 sium. If the magnesium is present only in relatively small 
 quantity, the amount carried down may be disregarded; 
 otherwise a second precipitation should be made as follows: 
 The solution is allowed to stand until the precipitate has 
 subsided; this will require some hours. The supernatant 
 liquid is poured off through a filter, the precipitate washed 
 by decantation, then dissolved in hydrochloric acid, water 
 
TECHNIC EXAMINATIONS. 89 
 
 added, then ammonium hydroxid and a small quantity 
 of ammonium oxalate. After the calcium oxalate has 
 thoroughly subsided it is filtered off, washed, and dried. If 
 quite small in amount, it is placed with the filter in a weighed 
 platinum crucible, ignited over the Bunsen burner for a 
 short time, and then over the blast lamp for from five to 
 fifteen minutes. The calcium is thus obtained in the form 
 of oxid, which is allowed to cool in the desiccator and 
 weighed. The weight thus obtained multiplied by 0.714 
 gives the weight of calcium. When the amount of precipi- 
 tate is large, it is better to remove it from the filter, and 
 heat it just short of redness until it assumes a grayish tint. 
 It then consists of calcium carbonate. To this is added 
 the ash of the filter. The weight of the calcium carbonate 
 multiplied by 0.4 gives the weight of calcium. 
 
 The calcium may be/ determined by titration. The 
 precipitate of calcium oxalate, after thorough washing, is 
 dissolved from the filter by warm, dilute, sulfuric acid, 
 heated to about 65 C., and titrated with decinormal per- 
 manganate until a pink tint is obtained. One c.c. of the 
 permanganate is equivalent to 0.0020 calcium; 0.0028 cal- 
 cium oxid; 0.0050 calcium carbonate. 
 
 The filtrates are mixed, slightly acidified with hydro- 
 chloric acid, concentrated and cooled, ammonium hydroxid 
 and sodium phosphate added in excess, stirred briskly 
 and allowed to stand in the cold for about twelve hours. 
 The precipitated ammonium magnesium phosphate is 
 brought upon a filter, that adhering to the sides of the vessel 
 being dislodged by rubbing with a glass rod tipped with 
 a piece of clean rubber tubing. It is washed with a solu- 
 tion made by mixing one part of the ammonium hydroxid 
 
90 ANALYTIC OPERATIONS. 
 
 of 0.96 sp. gr. with three parts of water. The precipitate 
 is dried, transferred to a platinum crucible, the filter ashed 
 separately and added to it, and the whole heated at first 
 gently and then to intense redness for several minutes. 
 After cooling, it is weighed. It consists of magnesium 
 pyrophosphate ; the weight multiplied by 0.218 gives the 
 weight of magnesium. 
 
 Manganese, if present in appreciable quantity, is sepa- 
 rated before the precipitation of the calcium, as follows: 
 The filtrate from the iron precipitate is slightly acidulated 
 with hydrochloric acid, concentrated, and the manganese 
 precipitated as sulfid by colorless or slightly yellow solu- 
 tion of ammonium sulfid. The flask, which should be 
 nearly full, is stoppered, allowed to rest in a moderately 
 warm place until the precipitate has thoroughly settled, 
 filtered, washed with dilute ammonium sulfid water, and 
 purified by dissolving in a small quantity of hydrochloric 
 acid and reprecipitating with ammonium sulfid. It is 
 filtered off, washed as before, dried, placed in a weighed 
 porcelain crucible, covered with a little sulfur, and ignited 
 in a current of hydrogen introduced into the crucible by a 
 tube passing through a hole in the cover. The pure man- 
 ganese sulfid thus obtained is allowed to cool and weighed. 
 The weight multiplied by 0.633 gi yes manganese. 
 
 Sulfates. Five hundred c.c. of the clear water are 
 slightly acidulated with hydrochloric acid, heated to boil- 
 ing, and barium chlorid solution added in moderate ex- 
 cess. The precipitated barium sulfate is allowed to sub- 
 side completely, collected upon a filter, washed thoroughly, 
 dried, and incinerated. The weight multiplied by 0.411 
 gives SO 4 . If the proportion is very low, it will be ad vis- 
 
TECHNIC EXAMINATIONS. 9 1 
 
 able to concentrate the water to one-fifth or one-tenth its 
 bulk before precipitating. 
 
 Control. Potassium, Sodium, and Lithium. From 
 250 to 1000 c.c. of the water, according to the amount of 
 solid matters present, are evaporated to dryness in a plati- 
 num dish, and the residue treated with a small amount of 
 water and sufficient dilute sulfuric acid to decompose the 
 salts present. The dish should then be covered and placed 
 upon the water-bath for five or ten minutes, after which 
 any liquid spurted on the cover is washed into the dish, the 
 whole evaporated to dryness and heated to redness. A 
 few drops of ammonium carbonate solution should then be 
 mixed with the residue, and the ignition repeated to insure the 
 removal of the last portions of free acid. In the majority 
 of cases the only basic elements present in considerable 
 quantity are calcium, magnesium, and sodium. The 
 sodium may be determined indirectly, therefore, by cal- 
 culating from the amount of calcium and magnesium 
 found, the calcium and magnesium sulfate in the residue, 
 and subtracting this sum, together with the silica, from the 
 total residue. 
 
 For the determination of potassium and sodium in ordi- 
 nary well and river waters, not less than two liters should 
 be employed. When lithium is to be determined, it is 
 generally necessary to use much more. In any case, as 
 the alkalies are to be weighed as chlorids, it is advisable, 
 if notable amounts of sulfates are present, to precipitate 
 them by addition of barium chlorid. 
 
 The water is evaporated to about 200 c.c., a slight excess 
 of calcium hydroxid added to the hot liquid, generally 
 three c.c. of thin milk of lime will be sufficient, and the 
 
92 ANALYTIC OPERATIONS. 
 
 heat continued for several minutes. It is then washed 
 into a 250 c.c. flask, disregarding the insoluble portion ad- 
 hering to the dish, which, however, should be thoroughly 
 washed, and the washings added to the flask. After cool- 
 ing, the flask is filled up to the mark with distilled water, 
 thoroughly mixed, the precipitate allowed to settle, and 
 the liquid filtered through a dry filter. Two hundred c.c. 
 of the filtrate are measured into another 250 c.c. flask, 
 ammonium carbonate and ammonium oxalate added, filled 
 with water up to the mark, mixed, allowed to settle, filtered 
 through a dry filter, 200 c.c. of the filtrate measured off, 
 and evaporated to thorough dryness in a platinum crucible, 
 heating very cautiously at the last stages, to avoid loss 
 by spurting. The low r -temperature burner is suited for 
 this purpose. The crucible is now covered and cautiously 
 heated to dull redness, cooled, and weighed. The residue 
 contains the potassium, lithium, and sodium as chlorids. 
 It contains, sometimes, also, traces of magnesium, which 
 may be removed by treating again with lime and ammonium 
 carbonate and oxalate. It is frequently of advantage, in 
 evaporating these saline solutions, to add, when the solu- 
 tion becomes concentrated, several cubic centimeters of 
 strong hydrochloric acid. This precipitates the greater 
 portion of the salts in a finely granular condition, and 
 renders loss by spurting less liable to occur. 
 
 If potassium and sodium chlorids only are present, the 
 residue is dissolved in a small quantity of water, an excess 
 of a concentrated neutral solution of platinum chlorid 
 added, evaporated to small bulk at a low heat on the water- 
 bath, some eighty per cent, alcohol added, allowed to 
 stand, the clear liquid decanted off on a small filter, and 
 
TECHNIC EXAMINATIONS. 93 
 
 the residue washed in this way several times by fresh, small 
 portions of eighty per cent, alcohol. The precipitate is 
 then washed on to the filter with alcohol, washed again 
 with eighty per cent, alcohol, thoroughly drie'd and trans- 
 ferred as far as possible to a watch-glass. The small por- 
 tion on the filter is dissolved off and the solution placed in 
 a weighed platinum dish and evaporated to dryness. The 
 main portion on the watch-glass is then added, and the 
 whole dried to a constant weight at about 260 F., cooled, 
 and weighed. The weight thus found multiplied by 0.3 
 gives the weight of potassium chlorid. This subtracted 
 from the combined weight of the chlorids gives the weight 
 of sodium chlorid. 
 
 Lithium, if present, is best separated before the treatment 
 with platinum chlorid. The following method, devised 
 by Gooch, gives good results: To the concentrated solution 
 of the weighed chlorids, amyl alcohol is added and heat 
 applied, gently at first, to avoid bumping, until the water 
 disappears from the solution and the point of ebullition 
 becomes constant at a temperature which is approximately 
 that at which the alcohol boils (270 F.), the potassium 
 and sodium chlorids are deposited, and the lithium chlorid 
 is dehydrated and taken into solution. The liquid is then 
 cooled, and a drop or two of strong hydrochloric acid added 
 to reconvert traces of lithium hydroxid in the deposit and 
 the boiling continued until the alcohol is again free from 
 water. If the amount of lithium chlorid be small, it will be 
 found in the solution and the potassium chlorid and sodium 
 chlorid in the residue, excepting traces which can be allowed 
 for. If the lithium chlorid exceed ten or twenty milligrams, 
 the liquid may be decanted, the residue washed with amyl 
 
94 ANALYTIC OPERATIONS. 
 
 alcohol, dissolved in a few drops of water, and treated as 
 before. For washing, amyl alcohol, previously dehydrated 
 by boiling, is to be used and the filtrates are to be measured 
 apart from the washings. In filtering, the Gooch filter 
 with asbestos felt may be used with advantage, applying 
 gentle pressure by the aid of the filter-pump. The crucible 
 and residue are ready for weighing after gentle heating 
 over the low-temperature burner. The weight of the in- 
 soluble chlorids is to be corrected by adding 0.00041 for 
 every 10 c.c. of amyl alcohol in the filtrate, exclusive of the 
 washings, if only sodium chlorid be present; 0.00051 for 
 every 10 c.c. if only potassium chlorid, and 0.00092 in the 
 presence of both these chlorids. 
 
 The filtrate and washings are evaporated to dryness in a 
 platinum crucible heated with sulfuric acid, the excess 
 driven off, and the residue ignited to fusion, cooled, and 
 weighed. From the weight is to be subtracted, for each 
 10 c.c. of filtrate, 0.0005, 0.00059, or 0.00109, according 
 as only sodium chlorid, potassium chlorid, or both were 
 present in the original mixture. 
 
 Hydrogen Sulfid. The following method is taken 
 from Button's "Volumetric Analysis": 
 Reagents Required : 
 
 Centinormal lodin. Dry, commercial iodin is intimately 
 mixed with one-fourth its weight of pure potassium iodid 
 and gently heated between two clock-glasses by resting 
 the lower on a hot plate. The iodin sublimes in a per- 
 fectly pure condition. It is allowed to cool under the 
 desiccator, 1.269 grams weighed out, together with 1.8 
 grams of pure potassium iodid, dissolved in about 50 c.c. 
 of water, and the solution made up exactly to a liter. The 
 
TECHNIC EXAMINATIONS. 95 
 
 liquid must not be heated, and care should be taken that 
 no iodin vapor is lost. One c.c. is equivalent to 0.00017 
 H 2 S. The solution is best prepared in stoppered bottles, 
 which should be completely filled and kept* in the dark. 
 It will not even then keep very long, and should be stan- 
 dardized by titration with a weighed amount of pure sodium 
 thiosulfate, which should be powdered previous to weighing, 
 and pressed between filter-paper to absorb any moisture. 
 Fifty c.c. of the iodin solution, when of full strength, will 
 require o. 1 24 gram of sodium thiosulfate. 
 
 Starch Indicator, See page 57. 
 Analytic Process : 
 
 Ten c.c., or any other necessary volume of the iodin 
 solution, is measured into a 500 c.c. flask, and the water 
 to be examined added until the color disappears. Five 
 c.c. of starch liquor are then added, and the iodin solution 
 run in until the blue copper appears; the flask is then filled 
 to the mark with distilled water. The respective volumes 
 of iodin and starch solution, together with the added water, 
 deducted from the 500 c.c., will show the volume of water 
 actually titrated by iodin. A correction should be made 
 as follows for the excess of iodin required to produce the 
 blue color: Five c.c. starch solution are made up with 
 distilled water to 500 c.c., iodin run in until the color matches 
 that in the test, and the volume of iodin solution so used 
 subtracted from the figure obtained in the first titration. 
 
 Hardness. C0 3 in Normal Carbonates. Waters con- 
 taining considerable quantities of calcium and magnesium 
 are said to be hard. Since the solution of calcium and 
 magnesium carbonate in water depends partly upon the 
 presence of carbon dioxid, boiling precipitates the greater 
 
9 6 ANALYTIC OPERATIONS. 
 
 portion of the carbonates, the result being to dimmish the 
 hardness i. e., to soften the water. Magnesium and 
 calcium sulfates and chlorids are not precipitated in this way. 
 Hardness, therefore, is divided into two classeSj temporary 
 and permanent, the former being that which may be re- 
 moved by boiling. The determination may be made either 
 by titration or by soap solution. 
 
 TITRATION METHOD. This method is due to Hehner. 
 Reagents Required : 
 
 Standard Sodium Carbonate. 1.06 grams of recently 
 ignited pure sodium carbonate are dissolved in water and 
 the solution diluted to 1000 c.c. One c.c. = 0.00106 gram 
 Na 2 CO 3 equivalent to o.ooi gram CaCO 3 . 
 
 Standard Sulfuric Acid. One c.c. of pure concentrated 
 sulfuric acid is added to about 1000 c.c. of water. Fifty 
 c.c. of the standard sodium carbonate are placed in a 
 porcelain dish, heated to boiling, a few drops of a solution 
 of methyl orange added, and the sulfuric acid cautiously 
 run in from a buret until the proper change of color occurs. 
 From the figure thus obtained, the extent to which the acid 
 should be diluted in order to make i c.c. of the sodium 
 carbonate equivalent to i c.c. of the acid may be calculated. 
 The proper amount of water is then added, and the solution 
 verified by again titrating. 
 Analytic Process : 
 
 Temporary Hardness. One hundred c.c. to 250 c.c. 
 of the water tinted with the indicator are heated to boil- 
 ing, and the sulfuric acid cautiously run in until the color- 
 change occurs. Each cubic centimeter required will repre- 
 sent one part of calcium carbonate or its equivalent per 
 100,000 parts of the water. 
 
TECHNIC EXAMINATIONS. 97 
 
 Permanent Hardness. To 100 c.c. of the water is added 
 an amount of the sodium carbonate solution more than suffi- 
 cient to decompose the calcium and magnesium sulfates, 
 chlorids, and nitrates present; usually a bulk 'equal to the 
 water taken will be more than sufficient. The mixture 
 is evaporated to dryness in a nickel or platinum dish, and 
 the residue extracted with distilled water. The solution 
 is filtered through a very small filter, and the filtrate and 
 washings titrated hot with sulfuric acid as above; or 25 
 c.c. of distilled water may be poured on the residue, and 
 the solution obtained filtered through a dry filter, the 
 filtrate measured and titrated. The difference between 
 the number of cubic centimeters of sodium carbonate used 
 and the acid required for the residue will give the permanent 
 hardness. 
 
 If the water contains sodium or potassium carbonate, 
 there will be no permanent hardness, and there will be 
 more acid required for the filtrate than the equivalent of 
 the sodium carbonate added. From this excess the quan- 
 tity of sodium carbonate in the water may be determined. 
 
 Since any alkali carbonate in the water would be erro- 
 neously calculated as temporary hardness by the direct 
 titration, the equivalent, in terms of calcium carbonate, of 
 the alkali carbonate present should be deducted from the 
 figure given by the titration in order to get the true tem- 
 porary hardness. 
 
 The total CO 3 in normal carbonates is given by the 
 direct titration of the water with dilute sulfuric acid. One 
 c.c. of the acid is equivalent to 0.0006 gram of CO 8 . 
 
 SOAP METHOD. Many chemists estimate hardness by 
 the use of soap solution. The following is a description 
 
98 ANALYTIC OPERATIONS. 
 
 of this method, as carried out in the laboratory of the 
 Massachusetts State Board of Health: 
 Reagents Required : 
 
 Standard Calcium Chlorid Solution. 0.2 gram of Ice- 
 land spar is dissolved in dilute hydrochloric acid in a por- 
 celain dish, the solution evaporated to dryness, redissolved 
 and reevaporated, until a perfectly neutral salt remains. 
 This is dissolved in water and made up to one liter. One 
 c.c. contains calcium equivalent to 0.0002 gram calcium 
 carbonate. 
 
 Soap Solution. 0.50 gram of best quality, dry, white, 
 Castile soap is cut into thin shavings, dissolved in a mix- 
 ture of 250 c.c. of 96 per cent, alcohol and 250 c.c. of dis- 
 tilled water, and allowed to stand overnight to settle; 50 
 c.c. of the clear liquid are then made up to one liter, enough 
 alcohol being used to keep all of the soap in solution. 
 Fifty c.c. of the standard solution of calcium chlorid, which, 
 according to the table, should take exactly 14.25 c.c. of 
 standard soap, are used to test the strength. The soap 
 solution thus prepared does not change perceptibly if 
 air has no access to it, and, if used with a siphon buret at- 
 tached to the bottle, will keep for five or six weeks or longer. 
 It contains 5.2 grams of Castile soap to the liter. 
 
 For the standardization of the soap, and for the deter- 
 mination of the hardness of any water, 50 c.c. of the sample 
 or of the standard calcium chlorid solution are placed in a 
 flask or bottle of 200 c.c. capacity, and of a convenient 
 shape, and the soap solution added, -f$ or -f$ of a c.c. at a 
 time, shaking well after each addition, until a lather is 
 obtained which is permanent for five minutes and covers the 
 entire surface of the liquid with the bottle placed on its side. 
 
TECHNIC EXAMINATIONS. 
 
 99 
 
 The following table gives the hardness corresponding to 
 the number of cubic centimeters of soap solution used in 
 the analyses: 
 
 C.C. OF 
 
 
 SOAP 
 
 HARDNESS. 
 
 SOLUTION 
 
 
 0.7 
 
 0.0 
 
 0.8 
 
 O.I 
 
 0.9 
 
 -3 
 
 .0 
 
 0.4 
 
 .1 
 
 0.6 
 
 .2 
 
 0.7 
 
 3 
 
 0.9 
 
 4 
 
 i.i 
 
 5 
 
 .2 
 
 .6 
 
 4 
 
 7 
 
 5 
 
 .8 
 
 .6 
 
 9 
 
 .8 
 
 2.0 
 
 9 
 
 2.1 
 
 2.O 
 
 2.2 
 
 2.2 
 
 2-3 
 
 2-3 
 
 2.4 
 
 2.4 
 
 2-5 
 
 2.6 
 
 2.6 
 
 2-7 
 
 2.7 
 
 2.8 
 
 2.8 
 
 2.9 
 
 2. 9 
 
 3-1 
 
 3- 
 
 3-2 
 
 3.1 
 
 3-3 
 
 3-2 
 
 3-5 
 
 3-3 
 
 3-6 
 
 3-4 
 
 3-7 
 
 3-5 
 
 3-9 
 
 3-6 
 
 4.0 
 
 C.C. OF 
 
 
 C.C. OF 
 
 
 SOAP 
 
 HARDNESS. 
 
 SOAP H, 
 
 VRDNESS. 
 
 SOLUTION 
 
 
 SOLUTION. 
 
 
 3-7 
 
 4.1 
 
 6.7 
 
 8-4 
 
 3-8 
 
 4.2 
 
 6.8 
 
 8-5 
 
 3-9 
 
 4-4 
 
 6.9 
 
 8.7 
 
 4.0 
 
 4-5 
 
 7.0 
 
 8.8 
 
 4.1 
 
 4-7 
 
 7.1 
 
 9.0 
 
 4.2 
 
 4-8 
 
 7.2 
 
 9.1 
 
 4-3 
 
 5.0 
 
 7-3 
 
 9.2 
 
 4-4 
 
 5.1 
 
 7-4 
 
 9.4 
 
 4-5 
 
 5-2 
 
 7-5 
 
 9-5 
 
 4.6 
 
 5-4 
 
 7.6 
 
 9-7 
 
 4-7 
 
 5-5 
 
 7-7 
 
 9.8 
 
 4-8 
 
 5-7 
 
 7-8 
 
 IO.O 
 
 4-9 
 
 5-8 
 
 7-9 
 
 IO.I 
 
 
 6.0 
 
 8.0 
 
 10.3 
 
 5- 1 
 
 6-. i 
 
 8.1 
 
 10.4 
 
 5-2* 
 
 6.2 
 
 8.2 
 
 10.6 
 
 5-3 
 
 6.4 
 
 8-3 
 
 10.7 
 
 5-4 
 
 6-5 
 
 8.4 
 
 10.9 
 
 5-5 
 
 6.7 
 
 8-5 
 
 II.O 
 
 5-6 
 
 6.8 
 
 8.6 
 
 II. 2 
 
 5-7 
 
 7.0 
 
 8-7 
 
 n-3 
 
 5-8 
 
 
 8.8 
 
 
 5-9 
 
 7-2 
 
 8.9 
 
 1 1. 6 
 
 6.0 
 
 7-4 
 
 9.0 
 
 11,8 
 
 6.1 
 
 7-5 
 
 9.1 
 
 11.9 
 
 6.2 
 
 7-7 
 
 9.2 
 
 12. 1 
 
 6-3 
 
 7-8 
 
 9-3 
 
 12.2 
 
 6.4 
 
 8.0 
 
 9-4 
 
 12.4 
 
 6-5 
 
 8.1 
 
 9-5 
 
 I2 -5 
 
 6.6 
 
 8.2 
 
 
 
 The soap solution must be added in small quantities, 
 especially in the presence of magnesium compounds. If 
 much carbonic acid be liberated, it is well to remove it by 
 suction. The table given above does not apply to hard- 
 ness above 12.5. If the water tested requires more than 
 
100 ANALYTIC OPERATIONS. 
 
 10 c.c. of the standard soap solution, a smaller portion of 
 25 c.c., 10 c.c., or even 2 c.c., as the case may require, 
 is measured out and made up to a volume of 50 c.c. with 
 recently distilled water. This will keep the results com- 
 parable with each other, although the dilution introduces 
 some error into the calculation. 
 
 If the hardness of a water is given as 9.0, it means that 
 in 100,000 pounds of water there is of calcium and mag- 
 nesium salts a quantity which gives the same hardness to 
 water which would be given by nine pounds of calcium 
 carbonate. In order to soften this water for manufacturing 
 purposes, about nine pounds of soda ash will be required, 
 and for laundry purposes about ninety pounds of soap. 
 
 Free and Half-bound Carbonic Acid. Several methods 
 for the determination of these data have been devised. 
 Pettenkofer's is much used, but F. B. Forbes and G. H. 
 Pratt, after careful study of different methods, favor the 
 Lunge-Trillich (also termed the Seyler) method, which 
 they describe as follows: 
 
 One hundred c.c. of the sample are placed in a tall glass 
 cylinder, by means of a siphon (in order to avoid contact 
 with air), 6 drops of neutral alcoholic solution of phenol- 
 phthalein added, and -f$ sodium carbonate run in from a 
 buret with careful stirring, until a faint permanent pink 
 is obtained. If the water contains much free carbonic 
 acid, it is better to take less than 100 c.c., and in every case 
 care must be taken not to stir the sample so vigorously as 
 to cause loss of the acid, nor to proceed so slowly that it 
 may be absorbed from the air. The solutions must be 
 carefully standardized and preserved so that they do not 
 absorb the acid. The fixed carbonic acid is determined on 
 
TECHNIC EXAMINATIONS. IOI 
 
 another portion of the sample by Hehner's method as 
 given above. . In waters acid to phenolphthalein this will 
 be equal to the half-bound. 
 
 When the water is alkaline to phenolphthalein, the 
 alkalinity with this indicator is first determined, then the 
 total alkalinity by Hehner's method. Twice the phenol- 
 phthalein alkalinity subtracted from the total alkalinity 
 gives the half-bound acid, no free acid being present in 
 this case, and the half -bound being less than the fixed. 
 If the water is neutral to phenolphthalein, the half-bound 
 may be equal to the fixed. 
 
 Forbes and Pratt have modified the Pettenkofer methods 
 as follows: 
 
 Ground glass-stoppered bottles, holding approximately 
 480 c.c., are accurately calibrated by weighing completely 
 
 filled with water. The bottle is filled with the water to be 
 f ^ . 
 
 analyzed by means of a siphon, the glass stopper inserted, 
 leaving no air-bubble, and the neck of the bottle wiped dry. 
 The glass stopper is then carefully removed, and the 57 
 c.c. of the water withdrawn by means of an accurately 
 calibrated pipet, in order to make room for the reagents. 
 Three c.c. of strong barium chlorid solution (8 grams per 
 liter), 2 c.c. of saturated ammonium chlorid solution, and 
 50 c.c. of standard barium hydro xid are then introduced, 
 the bottle quickly stoppered, well shaken, and set aside 
 to settle. 
 
 There is now in the bottle an air space of only 2 c.c., 
 which is left to avoid the possibility of loss of liquid when 
 the stopper is inserted. After the precipitated carbonates 
 have completely settled out, several portions of 100 c.c. are 
 siphoned off and titrated with -$ sulfuric acid, which is 
 
102 ANALYTIC OPERATIONS. 
 
 prepared from decinormal acid, against which the barium 
 hydroxid is standardized, by carefully diluting with water 
 freed from carbonic acid by boiling. The barium hydroxid 
 that we use is approximately T N ^-, and is carefully pre- 
 served out of contact with the air, the bottle in which it is 
 kept being fitted with an arrangement whereby the air is 
 drawn through soda-lime before entering either the bottle 
 or the buret. The figure obtained by averaging several 
 results of titration of portions of 100 c.c. is taken as the true 
 value. 
 
 The use of this large quantity of water and the titration 
 of 100 c.c. portions reduce considerably the errors due to 
 the difficulty of obtaining the exact end-point, and those 
 due to inaccuracies of measurement. 
 
 Boric Acid. To detect it, add to one liter of the water 
 sufficient sodium carbonate to render it distinctly alkaline. 
 Evaporate to dryness, acidify with hydrochloric acid, 
 moisten a slip of turmeric paper with the liquid, and dry 
 it at a moderate heat. In the presence of boric acid the 
 paper will assume a distinct brown-red tint. 
 
 Analysis of Boiler Scale. If the scale is made up of 
 pieces of decidedly different quality, some being hard and 
 gritty, others soft and friable, separate tests should be 
 made on representative samples of each sort; but if the 
 general character is fairly uniform, it will be sufficient to 
 sample the entire mass and reduce about 5 grams to a fine 
 powder, finishing in an agate mortar. All of the quantity 
 selected as the sample should be equally finely powdered. 
 
 0.5 gram should be heated in a covered beaker with 
 moderately strong hydrochloric acid, until all soluble 
 matter is dissolved ; the liquid is then evaporated to dryness 
 
TECHNIC EXAMINATIONS. 
 
 I0 3 
 
 on the water-bath, redissolved in water containing some 
 hydrochloric acid, and filtered. The precipitate is silica. 
 The nitrate and washings are mixed and divided into 
 convenient parts. One part is used for the determination of 
 sulfates, and the other for iron oxid, alumina, calcium, and 
 magnesium, according to the 
 methods given on pages 87 
 to 90. Scale often contains an 
 appreciable amount of oil. 
 This may be determined by 
 extracting a known weight of 
 the fully produced material 
 with a petroleum spirit that 
 leaves no residue on evapora- 
 tion on the water-bath. 
 
 SPECTROSCOPIC EXAMI- 
 NATION. 
 
 For the ordinary spectro- 
 scopic examination of a water 
 a simple apparatus will suf- 
 fice. The arrangement shown 
 in the cut (Fig. 13) is a small 
 direct-vision spectroscope, 
 held in a universal stand, 
 with an adjustable burner as 
 the source of heat. 
 
 For the examination a liter or more should be evaporated 
 nearly to dryness, a little hydrochloric acid being added 
 near the end of the process, the residue placed in a narrow 
 strip of platinum foil, having the sides bent so as to retain 
 
 FIG. 13. 
 
104 ANALYTIC OPERATIONS. 
 
 the liquid, and heated in the flame. While this method 
 will, be sufficient in many cases, a far better plan is to 
 separate the substance sought for in a state of approximate 
 purity and then examine with the spectroscope. Very 
 small traces of lithium, for instance, may be detected as 
 follows: To about a liter of the water sufficient sodium 
 carbonate is added to precipitate all the calcium and mag- 
 nesium, and the liquid boiled down to about one-tenth its 
 bulk; it is then filtered, the filtrate rendered slightly acid 
 with hydrochloric acid, and evaporated to dryness. The 
 residue is boiled with a little alcohol, which will dissolve 
 out the lithium chlorid. The alcoholic solution is evapo- 
 rated to dryness, the residue taken up with a little water 
 and tested in the flame. 
 
 In order to identify with certainty any line which may 
 be obtained, it is only necessary to hold in the flame at 
 the same time a wire which has been dipped in a solution 
 of the substance supposed to be present and to note whether 
 the lines produced by it and the material under examination 
 are identical. 
 
 SPECIFIC GRAVITY. 
 
 In the great majority of cases the determination of 
 specific gravity is not essential. Ordinary river, spring, 
 and well waters contain such small proportions of solid 
 matter that it is usually the practice to take a measured 
 volume and to assume its weight to be that of an equal 
 bulk of pure water. If the proportion of solids be high, a 
 determination of the specific gravity may be desirable. 
 For this purpose the specific gravity bottle may be used. 
 This consists merely of a small flask provided with a finely 
 
TECHNIC EXAMINATIONS. 105 
 
 perforated glass stopper. The bottle is weighed first alone, 
 then filled with distilled water at 60 F., and finally with 
 the water under examination at the same temperature. In 
 filling the bottle, the liquid is first brought* to the proper 
 temperature, the bottle completely filled, the stopper in- 
 serted, and the excess of water forced out through the 
 perforation and around the sides of the stopper carefully 
 removed by bibulous paper. The weight of the water 
 examined divided by the weight of the equal bulk of dis- 
 tilled water at the same temperature gives the specific 
 gravity. 
 
 Another method, and one which gives very satisfactory 
 results, is by the use of a plummet. This may conveniently 
 consist of a piece of a thick glass rod of about 10 c.c. in 
 bulk, or of a test-tube weighted with mercury and the open 
 end sealed in the flame. The plummet is suspended to the 
 hook of the balance by means of a fine platinum wire and 
 its weight ascertained. It is then immersed in distilled 
 water at 60 F., and the loss in weight noted. The figure 
 so obtained is the weight of a bulk of water equal to that 
 of the plummet. This having been determined, the specific 
 gravity of any water may be found by immersing in it the 
 plummet and noting the loss in weight. This, divided by 
 the loss suffered in pure water, gives the specific gravity. 
 
INTERPRETATION OF RESULTS. 
 
 STATEMENT OF ANALYSIS. 
 
 The composition of water is generally expressed in terms 
 of a unit of weight in a definite volume of liquid, but much 
 difference exists as to the standard used. The decimal 
 system is very largely employed, the proportions being 
 expressed in milligrams per liter, nominally parts per mil- 
 lion ; or in centigrams per liter, nominally parts per hundred 
 thousand. The figures are often given in grains per im- 
 perial gallon of 70,000 grains, or the U. S. gallon of 58328 
 grains. In this work the composition is always expressed 
 in milligrams per liter. This ratio is practically equivalent 
 to parts per million, except in case of water very rich in 
 solids, a liter of which will weigh notably more than one 
 million milligrams. Factors for converting the different 
 ratios are given at the end of the book. 
 
 From the analysis of a water it is rarely possible to ascer- 
 tain the exact arrangement of the elements determined, but 
 it is the custom to assume arrangements based upon the 
 rule of associating in combination elements having the 
 highest affinities, modifying this system by any inferences 
 derived from the character or reactions of the water itself. 
 It has been demonstrated that, even in the case of mixtures 
 of salts producing no insoluble substances, partial inter- 
 change of the basylous and acidulous radicles takes place. 
 In a solution of sodium chlorid and potassium sulfate 
 
 106 
 
SANITARY APPLICATIONS. 1 07 
 
 sodium sulfate and potassium chlorid will be found, as 
 well as the original salts. When the conditions are ren- 
 dered more complex by the addition of other substances, 
 it is obviously impossible to determine the exact arrange- 
 ment. In view of these facts, it is preferable to express 
 the composition of a water by the proportion of each ele- 
 ment or radicle present. In this way a water containing 
 K 2 SO 4 will be expressed in terms of K and SO 4 , respec- 
 tively. In the case of bodies like CO 2 and SiO 2 , which 
 may possibly exist free in the water, their proportion is 
 expressed as such. It frequently occurs that the character- 
 istics of some of the compounds in a water are sufficiently 
 marked to indicate their presence, and there can be no 
 objection to suggesting, in connection with the analytic 
 statement, the inferences which may thus be drawn. 
 
 The organic matters, or derived products, are best 
 stated in terms of the nitrogen which they contain, thus 
 permitting a comparison of the different stages of decom- 
 position. It is inadvisable to represent the amount of 
 unchanged organic matter in terms of oxalic acid, as has 
 been suggested, or to express the nitrogen in terms of 
 albumin, or any other supposititious compound. 
 
 The results of bacteriologic examinations should, as a 
 rule, be reported as "points of microbic life" in the given 
 volume of water. Many operators, however, report the 
 number of points as "colonies" or even "bacteria." 
 
 SANITARY APPLICATIONS. 
 
 Judgment upon the analytic results from a given sam- 
 ple of water depends upon the class to which it belongs, 
 and to the particular influences to which it has been sub- 
 
108 INTERPRETATION OF RESULTS. 
 
 jected. A proportion of total solids which would be sus- 
 picious in a rain or river water, would be without signifi- 
 cance in that from an artesian well. On the other hand, a 
 subsoil water of unobjectionable character would contain a 
 proportion of nitrates which would be inadmissible in the 
 case of a river or deep water. Location has also much 
 bearing in the case; subsoil waters near the sea will be 
 found to contain, without invoking suspicion, proportions 
 of chlorin which would be ample to condemn the same 
 sample if derived from a point far inland. Hence the im- 
 portance of recording, at the time of collection, all ascer- 
 tainable information as to the surroundings and probable 
 source of the water. 
 
 Analyses of surface waters have little value, unless sup- 
 plemented by a careful survey of the watershed to deter- 
 mine sources of pollution. Such survey will often discover 
 conditions sufficient to condemn the supply, even though 
 the analyses may be satisfactory. Indeed, it may be taken 
 as a fundamental principle that surface water from even 
 a sparsely populated district will be unsafe for use unless 
 efficiently filtered. 
 
 Color, Odor, and Taste. Water of the highest purity 
 will be clear, colorless, odorless, and nearly tasteless. 
 While in some cases a decided departure from this stand- 
 ard may give rise to suspicion, analytic observations are 
 necessary to decide the point. Water highly charged with 
 mineral matters will possess decided taste, vegetable 
 matters may communicate distinct color; but, on the other 
 hand, it may be highly contaminated with dangerous sub- 
 stances and give no indications to the senses. Well- 
 waters occasionally become offensive in odor, from pene- 
 
SANITARY APPLICATIONS. 1 09 
 
 tration of tree roots. The odor often recalls that of 
 hydrogen sulfid. Sulfids are, indeed, often formed in such 
 cases by the abstraction of oxygen from sulfates under 
 the influence of microbes. Such waters are often used 
 without apparent injury, but it is probable that if direct 
 pollution occurs, the danger would be enhanced by the 
 presence of the vegetable matter. 
 
 Surface waters collected in reservoirs or ponds often 
 become very offensive from the growth of algae, but apart 
 from the disgust created by the water, it is not known that 
 any harmful results occur to those using it. 
 
 Turbidity may be due to several causes, of different 
 degrees of danger, but is always objectionable. 
 
 Total Solids. Excessive proportions of mineral solids, 
 especially of marked physiologic action, are known to 
 render water non-potable, but no absolute maximum or 
 minimum can be assigned as the limit of safety. Dis- 
 tilled water and waters very highly charged with mineral 
 matter have been used for long periods without ill effects. 
 The popular notion that the so-called hard waters con- 
 duce to the formation of urinary calculi is not borne out 
 by surgical experience or statistical inquiry. Many urinary 
 calculi are composed of uric acid, and are the results of 
 disorders of the general nutritive functions. 
 
 Sanitary authorities have fixed an arbitrary limit of total 
 solids of about six hundred parts per million, but many 
 artesian waters in constant use exceed this. An instance 
 is found in the well on Black's Island, near Philadelphia, 
 which contains nearly twelve hundred parts per million, 
 is very agreeable in taste, and has been in constant use for 
 some years by a number of persons without injury. The 
 
110 INTERPRETATION OF RESULTS. 
 
 assertion that water to be wholesome must contain an 
 appreciable proportion of total solids is also not demon- 
 strated by clinical experience. A discussion of the effects 
 of special mineral ingredients e. g., magnesium sulfate, 
 ferrous carbonate, etc. belongs to general therapeutics. 
 
 The odor produced on heating the water residue is often 
 of much use in detecting contamination. Odors similar 
 to those produced by heating glue, hair, rancid fats, urine, 
 or other animal products, will give rise to grave suspicion. 
 On the other hand, a more favorable judgment may be 
 given when the odor recalls those given off in the heating 
 of non-nitrogenous vegetable materials, such as wood-fiber. 
 
 Poisonous Metals. The proportion of iron in water 
 constantly used for drinking purposes should not much 
 exceed three parts per million. Lead, copper, arsenic, 
 and zinc must be considered dangerous in any amount, 
 though it appears that zinc and copper, being least cumu- 
 lative, are rather less objectionable in minute amount than 
 the others. Concerning the limit of safety with mangan- 
 ese and chromium very little is known, but their presence 
 in appreciable quantity must be looked upon with suspicion. 
 
 Chlorids and Phosphates. Chlorids principally so- 
 dium chlorid and phosphates are abundantly distributed 
 in rocks and soils, and find their way into natural waters; 
 but while the former are freely soluble and remain in un- 
 diminished amount under all conditions to which the water 
 is subjected, all but small amounts of the latter are either 
 precipitated or removed by the action of living organisms. 
 Surface and subsoil waters ordinarily contain but a few 
 parts per million. Both chlorids and phosphates being 
 constant and characteristic ingredients of animal excre- 
 
SANITARY APPLICATIONS. Ill 
 
 tions, it is obvious that an excess of them in natural waters, 
 unless otherwise accounted for, will suggest direct con- 
 tamination. Proximity to localities in which sodium chlorid 
 is abundant, such as the sea- or salt-deposits, will deprive 
 the figure for the chlorin of diagnostic value, nor can any 
 indication of sewage or other dangerous pollution be in- 
 ferred from high proportion of chlorin in deep waters. 
 Further, it has be.en shown that the proportion of chlorin 
 in uncontaminated waters is tolerably constant, while 
 in water subjected to the infiltration of sewage the chlorin 
 undergoes marked variation in amount. In most cases, 
 therefore, a correct judgment can only be attained by com- 
 parison with the average character of the waters of the 
 same type in the district, and by examination at intervals 
 of the water in question. 
 
 As regards phosphates, Hehner, who has published a 
 series of analyses, states mat the presence of more than 0.6 
 part per million calculated as PO 4 should be regarded 
 with suspicion. On the other hand, the absence of phos- 
 phates affords no positive proof of the freedom from pol- 
 lution. Woodman, who has carefully investigated this 
 question, regards Hehner's limit as too strict. He would 
 fix i part per million as the minimum. He regards this 
 datum as valuable in judging of the sanitary quality of 
 the sample. 
 
 Nitrogen from Ammonium Compounds. Ammonium 
 compounds are usually the results of the putrefactive fer- 
 mentation of nitrogenous organic matter; they may also 
 be the product of the reduction of nitrites and nitrates 
 in presence of excess of organic matter. In either case, 
 therefore, they suggest contamination. Deep waters often 
 
112 INTERPRETATION OF RESULTS. 
 
 contain an excess of ammonium compounds, derived, in 
 large part, from the reduction of nitrates. Their presence 
 here is hardly ground for adverse judgment, since the 
 water, even though originally contaminated, has undergone 
 extensive nitration and oxidation, its organic matter con- 
 verted into bodies presumably harmless, and microbes have 
 perished. Such waters, indeed, usually show only traces 
 of unchanged organic matter. 
 
 Rain water often contains large proportions of ammo- 
 nium compounds; but here, also, the fact can not condemn 
 the water, since it does not indicate contamination with 
 dangerous organic matter. 
 
 The evolution of ammonia in the distillation of rain water 
 may continue indefinitely, the larger portion passing over 
 in the first distillates, but small quantities being present 
 even after the distillation has been much prolonged. The 
 same continuous evolution of ammonia has been noted in 
 waters containing urea, but in this case a larger proportion 
 is collected in the earlier distillates, nearly all coming over 
 before one-half the water has been distilled. 
 
 Nitrogen by Alkaline Permanganate (Nitrogen of 
 " albuminoid ammonia"). A large yield of ammonia 
 by boiling with alkaline potassium permanganate will, of 
 course, point to an excess of nitrogenous organic matter. 
 The inferences to be drawn depend upon the origin and 
 condition of the organic material. If animal, the water 
 may at once be condemned as unsafe. Waters containing 
 excessive amounts even of vegetable matter are not free 
 from objection, since they have frequently caused persis- 
 tent diarrhea. If the organic matter, whether animal or 
 vegetable, is in a state of active decomposition, it is doubly 
 
SANITARY APPLICATIONS. 113 
 
 objectionable. Mallet has called attention to the fact 
 that such waters, as a rule, yield ammonia rapidly, whereas 
 non-decomposing material yields it but slowly, and he 
 points out the importance, therefore, of notirrg the rate at 
 which the ammonia collects in the distillate. 
 
 Smart has observed that water containing fermenting 
 vegetable matter is colored yellow by boiling with sodium 
 carbonate. 
 
 Inferences as to the source of the organic matter can 
 usually be drawn from the amount of chlorin and nitrates 
 present. If the chlorin be high, i. e., in excess of the 
 average of the district, it may be inferred that the mate- 
 rial is, in great part, of animal origin. In this case the 
 nitrates will either be high or entirely absent, according as 
 the contaminating matter has passed through soil or enters 
 the water directly. 
 
 A large amount of vegetable matter will, as a rule, show 
 itself by the color it imparts to the water. 
 
 Total Nitrogen. Drown and Martin's results with 
 surface waters indicate that the total nitrogen obtained by 
 their process is about twice that obtained by alkaline per- 
 manganate. The experiments made by Dr. Beam and my- 
 self accord with this. Further observation on different 
 waters and by different observers will be required to deter- 
 mine the value to be assigned to the figures obtained by 
 this method. This method is especially suitable for study- 
 ing the effects of nitration, storage, etc., on the nitrogenous 
 organic matter in water. 
 
 Nitrogen as Nitrites. Nitrites are present in water 
 as the result either of incomplete nitrification of ammo- 
 nium, or the reduction of already formed nitrates, under 
 
114 INTERPRETATION OF RESULTS. 
 
 the influence of reducing agents or microbes. Since they 
 are transition products, their presence in water is usually 
 evidence of existing fermentative changes, and, further, 
 may be taken as indicating that the water is unable to 
 dispose of the organic contamination. When, however, 
 the conditions are such that oxidation can not take place, 
 nitrites may persist for a long time. This sometimes 
 occurs in deep waters in which fermentative changes have 
 long since ceased, but oxygen is not available. These 
 contain not infrequently small amounts of nitrites, to 
 which the same degree of suspicion can not be attached. 
 When nitrites are found in these waters, the possibility of 
 their introduction from polluted subsoil water, through 
 defective tubing, must not be overlooked. Rain water, 
 also, sometimes contains nitrites derived from the air, and 
 therefore not indicative of any putrefactive change. The 
 presence of measurable quantities of nitrites in river or 
 subsoil water is sufficient ground for condemnation. 
 
 Nitrogen as Nitrates. Nitrates are the final point in 
 the oxidation of nitrogenous organic matter, especially 
 animal matters. Rain water and that from mountain 
 streams and deep wells, except from cretaceous strata, 
 generally contain only traces, but river and subsoil waters 
 will always contain appreciable amounts, unless some re- 
 ducing action, such as recent sewage -pollution, is at work. 
 When, therefore, a water contains enough mineral matter 
 to demonstrate its percolation through soil, and at the 
 same time is free from nitrates or contains only traces, the 
 occurrence of a destructive fermentation may be inferred. 
 These cases are not uncommon among well-waters, and 
 the samples are generally turbid from suspended organic 
 
SANITARY APPLICATIONS. 115 
 
 matter. Decided departure, either by increase or de- 
 crease, from the proportion of nitrates usual in the same 
 class of water in any district may be taken as evidence of 
 contamination. 
 
 Oxygen-consuming Power. Sanitary authorities differ 
 very much as to the significance of this datum. Attempts 
 have been made to fix maximum limits for the various 
 types of water, and also to gage the character and con- 
 dition of the organic matter by observing the rate at which 
 the oxidation takes place, but no positive conclusions can 
 be given. In general, it may be said that a sample which 
 has 'high oxygen-consuming power will be more likely 
 to be unwholesome than one which is low in this respect; 
 but the interferences are so numerous, and the suscep- 
 tibility to oxidation of different organic matters, of even 
 the same type, is so different, that the method is at best 
 only of accessory value. ' It is especially suitable for con- 
 secutive determinations on the same supply. 
 
 The following proportions are given by Frankland and 
 Tidy as the basis of interpreting the results of this method: 
 
 OXYGEN ABSORBED IN THREE HOURS. 
 
 High organic purity, 0.05 parts per million. 
 
 Medium purity, 0.5 to 1.5 " " " 
 
 Doubtful, 1.5 to 2.1 " " " 
 
 Impure, over 2.1 
 
 For the method with acidified permanganate at the 
 boiling heat, the German chemists, who employ it largely, 
 regard an absorption of 2.5 parts of oxygen per million 
 as suspicious, and some sanitary authorities have fixed 3.8 
 parts of oxygen per million as the highest permissible limit. 
 
n6 
 
 INTERPRETATION OF RESULTS. 
 
 Dissolved Oxygen. Full aeration of water is favorable 
 to the destruction of organic matter; a decided diminution 
 in the quantity of dissolved oxygen may show excess of 
 such matter and of microbic life. Gerardin has pointed 
 out that this diminution is associated with the development 
 of low forms of vegetable life, and Leeds has recorded 
 similar facts. These changes are more likely to take place 
 in still waters, and are frequently accompanied by dis- 
 agreeable odor and taste. In cases in which stored waters 
 become unpalatable, these facts should be borne in mind. 
 
 Hardness. The degree of hardness, unless very high, 
 has but little bearing on the sanitary value of water, but 
 is important in reference to its use for general household 
 purposes, in view of the soap-destroying power which hard 
 waters possess. 
 
 USUAL ANALYTIC RESULTS FROM UNCONTAMINATED WATERS. 
 Milligrams pet' Liter. 
 
 
 RAIN. 
 
 SURFACE. 
 
 SUBSOIL. 
 
 DEEP. 
 
 Total solids, 
 Chlorin, 
 
 5 to 20 
 Traces to i 
 
 15 upward 
 i to 10 
 
 30 upward 
 2 to 12 
 
 45 upward 
 Traces to large 
 
 
 
 
 
 quantity 
 
 Nitrogen by perman- 
 
 
 
 
 
 ganate, 
 Nitrogen as NH 4 , . . . 
 " nitrites, 
 
 0.08 to 0.20 
 
 O.2O tO 0.50 
 
 None or 
 
 0.05 to 0.15 
 o.oo to 0.03 
 None 
 
 0.05 to o.io 
 o.oo to 0.03 
 None 
 
 0.03 to o.io 
 Generally high 
 None or traces 
 
 
 traces 
 
 
 
 
 " nitrates, . 
 
 Traces 
 
 0.75 to 1.25 
 
 i-5 to 5 
 
 o.oo to 3 
 
 Inferences from Culture Methods. No absolute limit 
 as to the number of ordinary microbes can be fixed. Some 
 bacteriologists have fixed the maximum of 100 per cubic 
 centimeter, but this is arbitrary. An appreciable number 
 
ACTION OF WATER ON LEAD. 1 17 
 
 of microbes of the intestinal type will be a basis for con- 
 demnation of the water. 
 
 There is, however, one field of inquiry in which even 
 mere microbe-counting has value; that is" in comparing 
 samples of the same water before and after some treatment 
 or other incident. In these studies the method is suffi- 
 ciently free from fallacy to make the results trustworthy 
 when they are conducted in a strictly uniform manner; 
 thus, if a river water supplied to a filter be studied daily 
 by examination of repeated samples before and after filtra- 
 tion, inoculating separate portions of the same culture- 
 medium, and multiplying the results to such an extent as 
 to eliminate accidental differences, a comparison between 
 the water before and after filtration may be safely made as 
 to the proportion of microbes removed. Moreover, special 
 microbes of highly characteristic properties may be intro- 
 duced in large quantities into the water, and by subse- 
 quent culture the extent to which these are removed may 
 be satisfactorily recognized. 
 
 ACTION OF WATER ON LEAD. 
 
 The almost universal use of lead pipes for conveying 
 water, and the facility with which some waters corrode 
 and dissolve the metal, make it a question of moment to 
 determine the cause of this action and to devise means for 
 its prevention. The subject has received considerable 
 attention within the last few years, and the conditions which 
 determine corrosion are now fairly understood. As a rule, 
 it is found that waters free from mineral matter dissolve 
 lead with facility, especially in the presence of oxygen. 
 Some very soft waters are entirely without action, and 
 
Il8 INTERPRETATION OF RESULTS. 
 
 this was unexplained until a few years ago, when Messrs. 
 Crookes, Odling, and Tidy found that the action was con- 
 trolled by the amount of silica contained in the water. 
 They found that those soft waters which, when taken from 
 the service pipes, contained a notable quantity of lead, 
 gave, on the average, three parts of silica per million; in 
 those in which there was no lead, the silica present amounted 
 to 7.5 per million, and in those in which the action was 
 intermediate, 5.5 parts per million. That it was really 
 the silica that conditioned the corrosion was confirmed by 
 laboratory experiments. They also found that the most 
 effective way of silicating a water is by passing it over a 
 mixture of flint and limestone. The reason for this was 
 pointed out later by Messrs. Camelry and Frew, who 
 showed that while calcium carbonate and silica both exert 
 a protective influence, calcium silicate is more effective 
 than either; and, further, that in almost all cases in which 
 corrosion took place, it was greater in the presence of 
 oxygen. This is particularly the case with potassium 
 and ammonium nitrates and with calcium hydroxid. The 
 reverse is true of calcium sulfate, which is more corrosive 
 when air is excluded. Their experiments also show that 
 the presence of calcium carbonate or calcium silicate, 
 altogether prevents corrosion by potassium and ammonium 
 nitrates. 
 
 As the result of an elaborate series of experiments, Miiller 
 concludes, that while chlorids, nitrates, and sulfates all 
 act upon lead pipes, no corrosion takes place in the pres- 
 ence of sodium acid carbonate, and that calcium car- 
 bonate, by taking up carbonic acid, acts in the same way. 
 This latter conclusion is at variance with the observations 
 
TECHNIC APPLICATIONS. IIQ 
 
 of Carnelly and Frew, who found that calcium carbonate 
 is equally effective when carbonic acid is excluded. Mliller 
 also states that surface waters, contaminated by sewage 
 and containing large amounts of ammoniacal compounds, 
 will dissolve lead under all circumstances. 
 
 Allen has shown that water containing free acid, in- 
 cluding sulfuric acid, acts energetically upon lead. This 
 is not surprising in view of the later experiments, which 
 prove that even calcium sulfate is corrosive. Later, W. 
 Carleton- Williams found that even in the presence of free 
 acid, corrosion may be prevented by the addition of suffi- 
 cient silica. His experiments also confirm the view gener- 
 ally held, that soluble phosphates protect lead to a marked 
 degree. 
 
 The following is a summary of the more important ob- 
 servations on this subject: 
 
 Corrosive: Free acid or alkalies, oxygen, nitrates, par- 
 ticularly potassium and ammonium nitrates, chlorids, and 
 sulfates. 
 
 Non-corrosive and preventing corrosion by the above: 
 Calcium carbonate, sodium acid carbonate, ammonium 
 carbonate, calcium silicate, silica, and soluble phosphates. 
 
 TECHNIC APPLICATIONS. 
 
 Boiler Waters. The main conditions affecting the 
 value of a water for steam-making purposes are its tendency 
 to cause corrosion and the formation of scale. Corrosion 
 may be due to the water itself, to the presence of free acids, 
 or to substances which form acids under the influence of 
 the heat to which the water is subjected. Pure water 
 e. g., distilled water exhibits a powerfully corrosive action 
 
120 INTERPRETATION OF RESULTS. 
 
 upon iron. The dissolved oxygen which all waters contain 
 also aids in the corrosion, and especially when accom- 
 panied, as is usually the case, by carbonic acid. There 
 is always greater rusting at the point at which the water 
 enters the boiler, since there the gases are driven out of 
 solution and immediately attack the metal. This is an 
 evil that obtains with all waters, and it is not customary, 
 in making examination for technic purposes, to deter- 
 mine the amount of these bodies. In water that has had 
 free access to air, the oxygen in solution is a tolerably con- 
 stant quantity, and it is sufficient to note the temperature 
 and refer to the table of amounts of oxygen dissolved in 
 water. The corrosive action of oxygen and carbonic acid 
 is especially noticeable in waters that are comparatively 
 pure, such as those derived from mountain springs. This 
 was repeatedly observed by Dr. William Beam, in the 
 examination of the waters used for the locomotives of the 
 Baltimore and Ohio Railroad. The waters which caused 
 the most corrosion were mainly those containing small 
 quantities of solid matter, the full amount of oxygen, and 
 considerable carbonic acid, but no other acid ot\ acid- 
 forming body. 
 
 Free acid, other than carbonic acid, is not often found 
 in water, and if present, renders the water unfit for use, 
 unless it be neutralized. Mine waters are the most likely 
 to contain free acid, sulfuric acid being generally present. 
 Sometimes the acidity is due to organic acids. These 
 act very injuriously on iron. Allen gives an example 
 of this in the water supplied to Sheffield, England, which 
 he found to contain an organic acid in amount equivalent 
 to from 3.5 to 10 parts of sulfuric acid per million. 
 
TECHNIC APPLICATIONS. 121 
 
 Magnesium chlorid is frequently present in waters, and 
 if in considerable quantity may be very harmful. At a 
 temperature of 310 F., corresponding to an effective 
 pressure of four atmospheres, magnesium chlorid reacts 
 with water to form magnesium oxid and hydrochloric acid, 
 the latter attacking the boiler, especially at the water-line. 
 If there be present at the same time considerable calcium 
 carbonate, the evil may be somewhat lessened, but, as Allen 
 has pointed out, and as we also have noticed, there may 
 still be corrosion, so that the presence of more than a small 
 quantity of the salt, say a grain or two to the gallon, may 
 be considered objectionable. Allen remarks that the 
 presence of a certain amount of sodium chlorid may pre- 
 vent this decomposition, the two chlorids combining to 
 form a stable double salt. The addition, therefore, of 
 common salt to a water containing magnesium chlorid may 
 act to diminish corrosion, a point which will bear further 
 investigation. 
 
 It has not been determined how far the presence of 
 nitrites, nitrates, and ammonia affects the quality of water 
 for steam-making purposes; but it is more than probable 
 that they act harmfully, especially the nitrates, which are 
 frequently present in large amount. 
 
 Scale is composed of matters deposited from the water 
 either by the decompositions induced by the heat or by 
 concentration. When the deposit is loose, it is termed 
 sludge or mud, and usually consists of calcium carbonate, 
 magnesium oxid, and a small amount of magnesium car- 
 bonate. The magnesium oxid is formed by the decompo- 
 sition of the magnesium carbonate and chlorid. 
 
 The formation of sludge is the least objectionable effect, 
 
122 INTERPRETATION OF RESULTS. 
 
 since it may readily be removed by "blowing off," pro- 
 vided that care is previously taken to allow the flues to 
 cool down so that when the water is removed the heat of 
 the flues may not bake the deposit to a hard mass. Waters 
 containing calcium sulfate form hard incrustations difficult 
 to remove and causing great loss of fuel by interfering 
 with the transmission of the heat to the water. It not 
 only forms a hard incrustation in itself, but becomes in- 
 corporated with the mud, and renders it also hard. The 
 hard scale will also contain practically all the silica and 
 the iron and aluminum present in the water, besides any 
 matters originally held in suspension. 
 
 It follows from the above that a water only temporarily 
 hard will, if care is taken in the management of the boiler, 
 cause the formation merely of a loose deposit of sludge 
 temporary hardness being due in the main to calcium and 
 magnesium carbonates. A water permanently hard will 
 probably form a hard scale, since such hardness is usually 
 due to calcium sulfate. 
 
 In accordance with these principles, the analysis of a 
 water for steam-making purposes may include the deter- 
 minations of free acid, total solid residue, SO 4 , Cl, Ca, Mg, 
 temporary and permanent hardness. In cases in which 
 the qualitative tests show but small amounts of SO 4 and 
 Cl, the analysis may be limited to the determinations of 
 the temporary and permanent hardness. 
 
 In the laboratory of the Pennsylvania Railroad an ap- 
 proximate determination of scale-forming ingredients is 
 made in the following manner: The total solids obtained 
 by evaporation are treated with diluted alcohol (fifty per 
 
TECHNIC APPLICATIONS. 123 
 
 cent.), and the undissolved residue is denominated "scale- 
 forming material." 
 
 It has been pointed out in an earlier chapter that it is 
 not possible to deduce from the analytic result the exact 
 forms in which the various elements are combined, but 
 since it is known that at the high temperature ordinarily 
 reached in boilers definite chemical changes occur, it is 
 safest to exhibit the maximum amount of corrosive and 
 scale-forming ingredients which the water under these cir- 
 cumstances could develop. Thus, since calcium sulfate 
 is practically insoluble in water above 212 F., the pro- 
 portion of calcium sulfate may be regarded as such as 
 would be formed by the total quantity of calcium or the 
 total quantity of SO 4 , according to which is present in the 
 larger amount. Similarly, as the decomposition of magne- 
 sium chlorid is induced by the high temperature of the 
 boiler, the analytic statement should indicate the maxi- 
 mum proportion of this compound obtainable from the 
 magnesium and chlorin present. These rules can not apply 
 absolutely to waters rich in alkali carbonates, since these 
 would neutralize any acid formed from the magnesium 
 chlorid, or even prevent its formation, and would prevent, 
 to a large extent, the formation of calcium sulfate. Much 
 remains to be determined concerning the effects of the 
 high temperature and concentration to which boiler waters 
 are subjected. 
 
 General Technic Uses. In regard to the quality 
 of water for technic other than steam-making purposes, 
 such as brewing, dyeing, tanning, etc., no detailed methods 
 or standards can be laid down. The nearest approach 
 to purity that can be secured in the supply will be of the 
 
124 INTERPRETATION OF RESULTS. 
 
 greatest advantage. The more objectionable qualities will 
 be large proportion of organic matter, especially if it dis- 
 tinctly colors the water, excessive hardness, and notable 
 amounts of iron or free mineral acid. It is said that one 
 part of iron per million will render water unsuitable for 
 bleaching establishments. It has been noted that a large 
 proportion of active microbes is injurious in the manufac- 
 ture of indigo. In artificial ice making, a very pure water 
 must be used if a clear and colorless product be desired. 
 Any suspended or dissolved coloring-matter will be con- 
 centrated by the freezing and appear in the bottom or 
 center of the mass. 
 
 The examination of sewage-effluents and waste waters 
 from manufacturing establishments is to be conducted 
 upon the same principles as for ordinary supplies, but 
 especial attention must be given to the presence of poison- 
 ous metals and free mineral acids. The latter interfere 
 with the normal self-purification of the water. For the 
 nitrogen determination, the Kjeldahl process will be found 
 more satisfactory than that by alkaline permanganate. 
 
 PURIFICATION OF DRINKING WATER. 
 The most obvious method of purifying water is by dis- 
 tillation. The process is too expensive for general use, 
 but is especially adapted for water intended for pharma- 
 ceutic or analytic purposes. It has also been used for 
 supplying vessels at sea and in tropic localities in which 
 the natural waters may be contaminated with malarial or 
 other germs. The majority of microbes are killed by 
 short exposure to a temperature of 212 F. ; hence, water 
 may be purified, on a small scale, by simple boiling. Freez- 
 
PURIFICATION OF DRINKING WATER. 
 
 125 
 
 ing does not have as beneficial an effect, many microbes 
 retaining vitality for a long time in ice, and even at very 
 low temperatures. 
 
 FIG. 14. 
 
 For the rapid sterilization of water^the Forbes sterilizer 
 is useful. Its efficiency has been ascertained. The in- 
 
126 INTERPRETATION OF RESULTS. 
 
 ternal construction is shown in figure 14. It is so arranged 
 that the incoming water is kept in lively boiling by which 
 it constantly overflows into the cooling tube, and, in de- 
 scending this, imparts its heat to the incoming current, thus 
 securing a heat-exchange which makes the operation 
 economic. The water is not distilled nor filtered, but 
 pathogenic microbes are killed. The illustration shows 
 a form intended for detached use, but arrangements are 
 also available for operation in connection with a constant 
 supply. 
 
 The self-purification of water that is, the destruction of 
 organic matter and pathogenic microbes, by reason of the 
 development of the ordinary microbes of putrefaction 
 occurs satisfactorily only in alkaline waters, hence, acid 
 effluents check this process. The addition of lime in suffi- 
 cient amount to give a slightly alkaline reaction will be 
 beneficial. 
 
 The conditions necessary to secure self-purification of 
 surface waters are not fully understood, and it is unsafe to 
 state that a polluted stream will purify itself in any given 
 distance. It must also be remembered that the dilution 
 of infected sewage by its introduction into a large volume 
 of uninfected water will assist, for a time at least, the 
 multiplication of pathogenic microbes. 
 
 The methods in general use for purifying water are 
 simple filtration and the removal of the impurities by ap- 
 propriate chemical agents. 
 
 Filtration. For household purposes forms of carbon, 
 stone, and sand filters are used, which yield clear filtrates, 
 but permit, sooner or later, the transmission of microbes. 
 The suspended matter in the water gradually accumulates 
 
PURIFICATION OF DRINKING WATER. 127 
 
 on the surface of the filter, and causes a great increase in 
 the number of the microbes, some species of which appar- 
 ently grow through the pores of the filter, and are carried 
 into the filtrate. The following are among the more 
 efficient forms of household filters: 
 
 Chamberlain- Pasteur Filter. This consists of tubes of 
 unglazed biscuit-ware, the number depending on the 
 size and required delivery of the filter. There are arrange- 
 ments for continuous filtration by attaching the tube to 
 the faucet; also forms adapted to simultaneous cooling and 
 filtration. The observations of Pasteur and others have 
 shown that this is a highly efficient filter, yielding for a con- 
 siderable time a filtrate entirely sterile. It requires oc- 
 casional cleaning, since, after continuous use, the microbes 
 may pass through the pores, probably by a process of 
 growth. An occasional boiling of the tubes in water would 
 be sufficient to overcome this difficulty. The Berkefeld 
 filter is of this type. 
 
 Many other forms of filters have been devised. Com- 
 prehensive comparative tests show that, except as to those 
 based on the principle of the Chamberlain-Pasteur filter, 
 but little time elapses before the filtrate contains numerous 
 microbes. 
 
 For the purification of water on the large scale the value 
 of sand filters has been so thoroughly established that the 
 method needs no further discussion. The construction 
 and operation of these filters are engineering questions 
 entirely. 
 
 Precipitation Methods. A small quantity of aluminum 
 sulfate added to natural waters is decomposed with the 
 formation of a flocculent precipitate of aluminum hydroxid, 
 
128 INTERPRETATION OF RESULTS. 
 
 which settles comparatively rapidly, and carries down with 
 it all suspended matters, as well as a large proportion of the 
 dissolved organic matters. Waters which contain such an 
 excess of organic matter as to be distinctly colored may 
 usually be made quite clear and colorless by this treatment. 
 One grain to the gallon will often suffice for the purpose, 
 but if very rapid subsidence is desired, more may be added. 
 
 This precipitation is a gradual process, and a water that 
 will give the test for aluminum immediately after filtering 
 may give none after twenty-four hours. It is not infre- 
 quently noted that such effluents, originally clear, become 
 cloudy on standing, in consequence of the separation of 
 aluminum hydroxid. On the addition of aluminum sul- 
 fate to brown surface waters there is also a precipitation 
 by the organic matters. A sample of the Cochituate River 
 water (Boston supply), of moderately deep color, to which 
 25 milligrams of alum to the liter had been added, when 
 filtered gave no reaction, even when 2.5 liters were con- 
 centrated for the test. An addition of 30 milligrams to 
 the liter could be detected without difficulty. 
 
 Several systems of filtration now in extended use employ 
 this precipitation method in conjunction with filters of 
 small area, the necessary flow being obtained by increased 
 pressure. The differences between the various forms are 
 chiefly in the mechanical arrangements for supplying the 
 water and for cleaning the filter. The material is generally 
 sand or coke; the cleaning is performed at short intervals, 
 by means of reverse currents of water. The aluminum 
 solution is introduced as needed by automatic apparatus. 
 
 These filters are efficient, and are suitable for the purifi- 
 cation of water for manufacturing establishments, and when 
 
PURIFICATION OF DRINKING WATER. 129 
 
 large basins are not available. It must be noted, how- 
 ever, that the use of aluminum sulfate will increase the 
 liability of the water to form hard scale. This can be 
 avoided by using some other aluminum salt. 
 
 The addition of an iron salt to water containing carbon- 
 ates is attended with decomposition and the formation of 
 a precipitate of ferric hydroxid. This reaction has been 
 employed as a means of purification. One of these meth- 
 ods was by passing the water through spongy iron, then 
 aerating to precipitate the iron, and filtering through sand. 
 The method is very efficient, but the spongy iron gradu- 
 ally chokes by oxidation and becomes useless. This diffi- 
 culty is removed by the use of iron borings or pun chin gs 
 contained in an iron cylinder, which is rotated while the 
 water passes through; the iron is brought into thorough 
 contact with the water, and there is sufficient abrasion to 
 keep its surface clean. 
 
 In the laboratory of the State Board of Health of Mass- 
 achusetts, Drown investigated the effect of various methods 
 of aeration, such as exposing water in bottles to the air 
 of the room, drawing a current of air through by means 
 of an aspirator, shaking it in a bottle by machinery, and 
 exposing it to air under pressure of from sixty to seventy- 
 five pounds. While no appreciable benefit so far as re- 
 gards the organic matter and its decomposition-products 
 occurs, aeration appears to prevent the growth of alg, 
 with the troublesome accompaniments of bad tastes and 
 odors. It may also have a beneficial effect upon ground 
 waters containing considerable amounts of iron. These 
 waters are often clear when first drawn, but become turbid 
 i 
 
130 INTERPRETATION OF RESULTS. 
 
 and yellow in a few hours by the separation of ferric hy- 
 droxid by oxidation. Waters from considerable depth 
 often contain so little free oxygen that this oxidation does 
 not occur until they reach the surface. By applying an 
 aeration method the change may be hastened, and by some 
 simple process of rapid nitration afterward applied, the 
 water will be made clear and remain so. 
 
 Filtration through bone charcoal, which contains con- 
 siderable calcium phosphate, will remove small amounts 
 of lead, copper, and arsenic. 
 
 Purification of Boiler Waters. The problems present 
 in the treatment of boiler waters are usually the removal 
 of the calcium carbonate and sulfate, and magnesium 
 carbonate and chlorid. Both carbonates are appreciably 
 soluble in pure water. About one grain of calcium car- 
 bonate to the gallon is usually stated to be the proportion 
 dissolved, but it has been pointed out by Allen that solu- 
 tions can be obtained containing twice this amount. If 
 the water contains carbonic acid, it will take up a much 
 greater proportion of the carbonates, but in this case they 
 will be deposited from the solution by boiling. This has 
 been accounted for by supposing the existence of soluble 
 bicarbonates, which are decomposed_by the boiling. Nearly 
 all of these carbonates can be thrown out of solution by 
 any means that will deprive the water of the carbonic acid. 
 Sodium hydroxid is often employed for the purpose, and 
 should be added in quantity just sufficient to form normal 
 sodium carbonate. If there are present in the water 
 calcium and magnesium chlorids and sulfates, these also 
 will be decomposed and precipitated by the sodium car- 
 
PURIFICATION OF DRINKING WATER. 131 
 
 bonate so formed. If the amount of sodium carbonate 
 formed is not sufficient to decompose all of these bodies, a 
 sufficient quantity should be added with the sodium hy- 
 droxid to effect the complete decomposition. The pre- 
 cipitate is allowed to settle or filtered off. 
 
 In cases in which the feed-water is heated before it enters 
 the boiler, it may only be necessary to add to the water 
 sodium carbonate in quantity sufficient to decompose the 
 calcium and magnesium chlorids and sulfates, since the 
 heat alone will suffice to throw down the carbonates. 
 
 Care should be taken in these precipitations that no 
 more sodium hydroxid is added than is required for the 
 precipitation, since any excess would tend to corrode the 
 boiler. 
 
 Clark's process consists in treating the water with calcium 
 hydroxid (lime-water). This precipitates the calcium and 
 magnesium carbonates by depriving the water of its free 
 carbonic acid. It has, of course, no effect upon the cal- 
 cium sulfate. It is to be noted that the proportion of 
 calcium hydroxid which is to be added must be calculated 
 from the amount of free carbonic acid existing in the water, 
 and not from the amount of carbonates to be removed. 
 The precipitate will usually require at least twelve hours 
 for complete subsidence, but after three or four hours the 
 water will be sufficiently clear for some purposes. If a 
 filter press is used, as in Porter's process, the time required 
 for clarification is very much shortened. Another advan- 
 tage of this process is the use of a solution of silver nitrate, 
 in order to determine more conveniently the proportion 
 of calcium hydroxid which is to be employed. The lime 
 is first slaked and dissolved in water, and the water to be 
 
132 INTERPRETATION OF RESULTS. 
 
 softened run in and thoroughly mixed with it. From time 
 to time small portions are taken out and a few drops of a 
 solution of silver nitrate added. As long as the lime is in 
 excess, a brownish coloration is produced. When this has 
 become quite faint, and just about to disappear, the addi- 
 tion of the water is discontinued, and, after a short time, 
 the water is filtered by means of the press. 
 
 Soluble phosphates added to a water precipitate com- 
 pletely in a flocculent condition any calcium, magnesium, 
 iron, or aluminum. This reaction can be best applied by 
 using the trisodium phosphate (Na 3 PO 4 -[~ i2H 8 O), which 
 is now a commercial article. By reason of the facility with 
 which this substance loses a portion of its sodium to acids, 
 it acts not only as a precipitant to the above materials, but 
 will neutralize any free mineral acid present in the water. 
 From evidence submitted by those who have used the pro- 
 cess on the large scale, it appears that not only is no hard 
 scale formed, but that scale already existing prior to its 
 use is gradually disintegrated and removed with the sludge. 
 Experiments indicate that no injury results from an excess 
 of the material; but the economical employment of the 
 method, especially with very hard waters, can only be 
 based upon a correct analysis, and an estimation of the 
 phosphate required for the precipitation. In many cases 
 the composition of the water will be such that a partial 
 precipitation will be sufficient. 
 
 Considerable success has been obtained by the use of 
 fluorids as precipitants of scale-forming elements. Sodium 
 aluminate has also been recommended. 
 
 Waters rich in ferrous compounds may be purified by 
 
IDENTIFICATION OF THE SOURCE OF WATER. 133 
 
 thorough aeration and nitration, the iron being separated 
 as ferric hydroxid. 
 
 The corrosive action of very pure waters is partially 
 abated by filtration through bone charcoal or by addition 
 of small amounts of lime. 
 
 IDENTIFICATION OF THE SOURCE OF WATER. 
 
 The determination of the course of underground streams, 
 and of communications between collections of water, is 
 often an important practical problem. In geologic and 
 sanitary surveys, valuable information may occasionally be 
 gained. The method generally pursued when connection 
 between water at accessible points is to be detected, is to 
 introduce at one point some substance not naturally exist- 
 ing in the water, and capable of recognition in small amount. 
 Lithium compounds are among the best for this purpose. 
 They are not frequent fngredients of natural waters, and 
 are easily recognized by the spectroscope. Lithium chlorid 
 is the most suitable. The quantity to be employed will 
 vary with circumstances. It scarcely needs to be stated 
 that the waters under examination should be carefully 
 tested for lithium before using the method. 
 
 When the lithium method is inadmissible, recourse must 
 be had to other substances of distinct character, such as 
 strontium chlorid, but this possesses the disadvantage that 
 a considerable amount may be rendered insoluble, and 
 thus lost in the ordinary transit through soil. Use has 
 been made of organic coloring matters of high tinctorial 
 power, one of the most suitable of which is fluoresce'in, 
 C 20 H 12 O 5 , a derivative of benzene. This will communi- 
 cate a characteristic and intense fluorescence to many 
 
134 INTERPRETATION OF RESULTS. 
 
 thousand times its weight of water. The coloration is 
 distinct only in alkaline liquids. Other colors, such as 
 anilin-red, may be employed. 
 
 I am indebted to Dr. F. P. Vandenburgh, who conducted 
 the investigation, for a description of an instance of the 
 application of the above methods. In a suit at law grow- 
 ing out of use of a creek for the supply of Syracuse, N. Y., 
 it was alleged that the creek supplied a spring which was 
 used by a manufacturing establishment. Tests of the 
 water of creek and spring for lithium were made, ten gallons 
 of each being evaporated, with negative results. Twenty- 
 five pounds of lithium carbonate were converted into 
 chlorid and poured into the stream about half a mile from 
 the spring. Samples of ten gallons each were taken out of 
 the spring by almost continual dipping during forty-eight 
 hours following. Twenty of these samples were examined 
 and lithium found in each. 
 
 Ten pounds of fluorescem were introduced at a point 
 about one mile above the spring, and the characteristic 
 fluorescence appeared at the spring about six hours after 
 its introduction into the creek. The greatest intensity of 
 color was between six and ten hours after its introduction. 
 
 A more important feature of the problem from a sanitary 
 point of view is the determination of the source of a given 
 current or collection of water, when such source is in- 
 accessible. Problems of this character are not infrequent 
 in large cities in which the systems of water-supply and 
 drainage are defective, thus giving occasion to accumu- 
 lations of water in cellars and similar places. Often, in 
 these cases, no extended explorations can be made, by 
 reason of the adjacent buildings and conflicting property 
 
IDENTIFICATION OF THE SOURCE OF WATER. 135 
 
 interests, and the question may arise whether the water 
 proceeds from a leaky hydrant, drain, sewer, or subsoil 
 current. It is obvious that in the case of the collection 
 of water in a cellar from causes other than surface washings 
 or entrance of rain, it must have passed through some 
 distance of soil, and in built-up districts will almost certainly 
 be charged with organic refuse. To correctly interpret 
 the results, it will be necessary to know the general char- 
 acter of the subsoil water of the district and the composition 
 of the public supply. As a rule, the transmission of water 
 through moderate distances of soil will not materially in- 
 crease the mineral constituents. Hence, if the sample con- 
 tains an excess of dissolved matters as compared with the 
 water-supply of the district, it may reasonably be inferred 
 that it is derived from a drain, sewer, or subsoil current. 
 In these investigations it will generally be sufficient to deter- 
 mine the total solids, odor on heating, chlorin,.nitrates, and 
 nitrites. 
 
 Occasionally, the analytic results will be ambiguous, and 
 it is advisable to make examinations of more than one 
 sample, since accidental circumstances, rain-fall, etc., may 
 affect the composition of the water. 
 
 Instances of the contamination of water by unusual sub- 
 stances are occasionally noted, and these sometimes afford 
 a clue to the source of the water. Among the instances 
 of this kind within my own experience may be noted the 
 contamination with petroleum and with soap. In the 
 former case it was evident that the contamination was from 
 a leaky pipe connecting two refineries. In the latter it 
 was shown to be derived from an adjoining building used 
 as a laundry. 
 
136 ANALYTIC DATA. 
 
 DATA FOR CALCULATION. 
 
 Parts per 100,000 X 0.7 = Grains per Imperial Gallon. 
 
 " 1,000,000 X 0-07 = " " " " 
 
 100,000 X 0.583 " " U. S. 
 
 " 1,000,000 X 0.058 
 
 ; 1,000,000 X 0.00833 = Pounds per 1000 U. S. Gal. 
 
 Grains" Imp. gallon -=- 0.7 = Parts per 100,000 
 
 -j- 0.07 " " 1,000,000 
 
 " " U. S. " -*- 0.583 " " 100,000 
 
 -*-' 0.058 " " 1,000,000 
 
 A1 2 3 , Xo. 53 =A1 
 
 AgCl, X 0.247 = C1 
 
 BaSO 4 , X 0.588 = Ba 
 
 BaS0 4 , X 0.411 = S0 4 
 
 BaS0 4 , X 0.342 = S0 3 
 
 B 2 3 , X 0.314 = B 
 
 CaO, X 0.714 = Ca 
 
 CaO, X 1-78 = CaCO 3 
 
 ' CaC0 3 , X 0.40 = Ca 
 
 Cl, X 1-65 := NaCl 
 
 Fe 2 3 , Xo. 7 =Fe 
 
 KC1, X 0.524 = K 
 
 2KC1, PtCl 4 , X 0.16 = K 
 
 2KC1, PtCl 4 ,____ X 0.307 = KC1 
 
 Mg 2 P 2 7 , X 0.218 = Mg 
 
 Mg 2 P 2 7 , X 0.853 = P0 4 
 
 Mg 2 P 2 7 , X 0.757 = MgC0 3 
 
 MnS, X 0.633 = Mn 
 
 NaCl, X 0.394 = Na 
 
 N, X 4-42 = N0 3 
 
 N, X3-27 -=N0 2 
 
 N, X 5-84 == Ca(N0 3 ) 2 
 
 N, X i.2i =NH 3 
 
 NH 3 , X 0.823 = N 
 
ANALYTIC DATA. 
 
 CONVERSION TABLE. 
 
 PARTS 
 
 PER 
 
 MILLION. 
 
 GRAINS PER 
 U.S. GALLON. 
 
 GRAINS 
 
 PER 
 
 IMP. GAL. 
 
 PARTS 
 
 PER 
 
 MILLION. 
 
 GRAINS PER 
 U.S. GALLON. 
 
 GRAINS 
 
 PER 
 
 IMP. GAL. 
 
 I 
 
 0.058 
 
 0.07 
 
 26 
 
 I.S08 
 
 1.82 
 
 2 
 
 0.116 
 
 0.14 
 
 27 
 
 1.566 
 
 1.89 
 
 3 
 
 0.174 
 
 0.21 
 
 28 
 
 1.624 
 
 1.96 
 
 4 
 
 0.232 
 
 0.28 
 
 29 
 
 1.682 
 
 2.03 
 
 5 
 
 0.290 
 
 0-35 
 
 3 
 
 1.740 
 
 2.10 
 
 6 
 
 0.348 
 
 0.42 
 
 3 1 
 
 1.798 
 
 2.17 
 
 7 
 
 0.406 
 
 0.49 
 
 3 2 
 
 1.856 
 
 2.24 
 
 8 
 
 0.464 
 
 0.56 
 
 33 
 
 1.914 
 
 2.31 
 
 9 
 
 0.522 
 
 0.63 
 
 34 
 
 1.972 
 
 2. 3 8 
 
 10 
 
 0.580 
 
 0.70 
 
 35 
 
 2.030 - 
 
 2-45 
 
 ii 
 
 0.638 
 
 0.77 
 
 36 
 
 2.088 
 
 2.52 
 
 12 
 
 0.696 
 
 0.84 
 
 37 
 
 2.146 
 
 2-59 
 
 13 
 
 -754 
 
 opi 
 
 38 
 
 2.204 
 
 2.66 
 
 14 
 
 0.812 
 
 0.98 
 
 39 
 
 2.262 
 
 2-73 
 
 15 
 
 0.870 
 
 1.05 
 
 40 
 
 2.320 
 
 2.80 
 
 16 
 
 0.928 
 
 1. 12 
 
 4i 
 
 2.378 
 
 2.87 
 
 17 
 
 0.986 
 
 I.I9 
 
 42 
 
 2.436 
 
 2-94 
 
 18 
 
 1.044 
 
 1.26 
 
 43 
 
 2-494 
 
 3.01 
 
 19 
 
 I.IO2 
 
 J -33 
 
 44 
 
 2-552 
 
 3.08 
 
 20 
 
 1. 1 60 
 
 1.40 
 
 45 
 
 2.610 
 
 3-i5 
 
 21 
 
 1.218 
 
 47 
 
 46 
 
 2.668 
 
 3-22 
 
 22 
 
 1.276 
 
 54 
 
 47 
 
 2.726 
 
 3-29 
 
 2 3 
 
 1-334 
 
 .61 
 
 48 
 
 2.784 
 
 3^36 
 
 24 
 
 1.392 
 
 .68 
 
 49 
 
 2.842 
 
 3-43 
 
 25 
 
 1.450 
 
 75 
 
 5 
 
 2.900 
 
 3-5 
 
INDEX. 
 
 A CIDS, action on lead, 117 
 " Actinic method for organic mat- 
 ter, 59 
 
 Action of water on lead, 117 
 Aeration of water, 116, 129 
 Agar, 78 
 
 Albuminoid ammonia, 44, 112 
 Alkali carbonates, determination of, 97 
 Alkaline permanganate, 42 
 Alum, action of, 127 
 
 , test for, 67 
 
 , use of, 127 
 
 Aluminum, determination of, 88 
 
 , test for, 67 
 
 Ammonia, albuminoid, 44, 112 
 
 , free, 43, in 
 
 free water, 41 
 
 process, 34 
 
 Ammonium chlorid, standard, 41 .' 
 
 molybdate, 60 
 
 Analysis, statement of, 106 
 Analytic operations, 22 
 Arsenic, detection of, 64 
 Artesian water, 16, 116 
 
 OACILLUS typhosus, 87 
 
 coli communis, 87 
 
 Bacteriologic examination, 74 
 Barium, detection of, 63 
 Biologic examination, 69 
 Boiler scale, 102, 121 
 
 water, 119 
 
 , purification of , 119 
 Boric acid estimation, 102 
 Bouillon, 77 
 
 compounds, removal of, 
 
 , determination of, 88 
 sulfate in boiler water, 123 
 , insolubility of, 123 
 
 - , determination of normal, 95 
 Carbonic acid, determination of, 100 
 Chlorin, determination of, 32 
 
 - , significance of, 1 10 
 Chromium, detection of, 63 
 
 Clarifying water, 24, 126 
 Clark's process, 131 
 Collection of samples, 22 
 Color comparator, 46 
 
 , determination of, 25 
 
 , significance of, 108 
 
 Comparison cylinders, 46 
 Conversion of ratios, 136, 137 
 Copper, detection of, 68 
 
 zinc couple, 52 
 
 Corrosion of boilers, 119 
 Cultivation of microbes, 81, 116 
 Culture-media, 76 
 
 "P\EEP water, 16, 116 
 
 *' Demijohn for water samples, 22 
 
 Denitrification, 19 
 
 Distilling apparatus, 34 
 
 pERRIC sulfate, standard, 34 
 * Ferrous ammonium sulfate, stan- 
 dard, 6 1 
 
 Filters, 71, 72, 126 
 Filtration, 127 
 Fluorescein, use of , 134 
 Forbes' sterilizer, 125 
 
 GALLON, Imperial, 106 
 , U. S., 106 
 Gelatin culture-media, 76 
 Ground water, 16, 116 
 
 TJARD scale, 122 
 
 * A water, softening of, 130 
 
 Hardness, 95, 116 
 
 , permanent, 96 
 
 , temporary, 97 
 
 Hydrogen sulfid, titration of, 94 
 
 IDENTIFICATION 
 x water, 133 
 Imperial gallon, 106 
 Indol reaction, 84 
 
 of source of 
 
 139 
 
140 
 
 INDEX. 
 
 Interpretation of results, 106 
 
 lodin, centinormal, 94 
 
 Iron, action of, in purification, 129 
 
 , determination of, 65, 88 
 
 , significance of, 1 10 
 
 T EAD, action of water on, 117 
 
 *"' determination of, 68 
 
 Lithium compounds, use of, 127 
 
 , detection of, 103 
 
 , separation of, 93 
 Litmus agar, 81 
 
 TV/TAGNESIA in boiler sludge, 121 
 *" Magnesium, determination of, 
 chlorid, effects of, 121 
 
 Manganese, detection of, 66 
 , determination of, 90 
 Microbes of water, 83 
 Micro-filter, 72 
 
 TyjESSLER reagent, 41 
 * ' Nesslerizing, 46 
 
 , determination of, 50 
 
 , formation of, 19 
 
 , significance of, 114 
 
 Nitrification, 19 
 
 Nitrites, determination of, 53 
 
 , formation of, 19 
 
 , significance of, 114 
 Nitrogen in ammonium, 44, 1 1 1 
 
 as nitrates, 50, 114 
 
 as nitrites, 53, 113 
 
 by permanganate, 44, 112 
 
 , oxidation of, 19 
 
 , total organic, 48, 113 
 
 /"}DOR, determination of, 27 
 
 ^ from residue, 31 
 
 , significance of, 108 
 
 consuming power, 55, 115 
 , dissolved, 61, 116 
 
 OARIETTI'S solution, 85 
 
 * Pasteur-Chamberlain filter, 127 
 
 Permanganate method, 44 
 
 standard, 56 
 
 Petri dish, 75 
 Phenol broth, 85 
 
 disulfonic acid, 5 1 
 
 , determination of, 60 
 
 , significance of, no 
 
 Potassium chromate solution, 32 
 
 , determination of, 93 
 
 iodid solution, 57 
 
 nitrate, standard, 51 
 
 permanganate, alkaline, 42 
 
 thiocyanate, 33 
 
 Potato culture, 80 
 Pure water, corrosive action of, 119 
 Purification of boiler water, 130 
 of drinking waters, 124 
 
 "DAIN water, 16, 116 
 
 ^ Ratios, conversion of , 136, 137 
 Reaction, 28 
 Residue, charring of, 3 1 
 Results, statement of, 106 
 River water, 16 
 
 CAMPLES, collection of, 22 
 Sand filters, 127 
 Sanitary examinations, 22 
 Scale, 102, 121 
 
 , analysis of, 102 
 
 Silica, determination of, 87 
 Silver nitrate, standard, 32 
 
 nitrite, preparation of, 54 
 
 test for organic matter, 59 
 Sludge, 121 
 
 Soap solution, 98 
 
 Sodium and potassium, separation of, 91 
 
 , carbonate solution, 90 
 
 , determination of, 92 
 
 hydroxid solution, 49 
 
 nitrite, standard, 54 
 
 thiosulfate, 57 
 
 Solids, significance of, 109 
 
 , total, 29 
 
 Source of water, tracing, 133 
 Specific gravity, 104 
 Spectroscopic examination, 103 
 Spongy iron filter, 129 
 Starch indicator, 57 
 Statement of analysis, 106 
 Subsoil water, 16, 116 
 Sulfates, determination of, 90 
 Sulfids, 20, 94 
 
 , determination of, 94 
 
 Surface water, 16 
 
 npECHNIC examinations, 87 
 A Total solids, 29 
 Turbidity, 27 
 
 , detection of, 64 
 
THIS BOOK IS DUE ON THE LAST DATE 
 STAMPED BELOW 
 
 30m-l,'15 
 
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 3458