Engineering Library THE POPULAR CHEMICAL DICTIONARY THE POPULAR CHEMICAL DICTIONARY A COMPENDIOUS ENCYCLOPAEDIA BY C. T. KINGZETT, F.I.C., F.C.S. AUTHOR OF "THE HISTORY, PRODUCTS, AND PROCESSES OF THE ALKALI TRADE" (LONGMANS); "ANIMAL CHEMISTRY; OR, THE RELATIONS OF CHEMISTRY TO PHYSIOLOGY AND PATHOLOGY " (LONGMANS) ; "NATURE'S HYGIENE AND SANITARY CHEMISTRY" (BAILLIERE, TINDALL AND cox); "CHEMISTRY FOR BEGINNERS AND SCHOOL USE" (BAILLIERE, TINDALL AND cox), ETC., ETC.; PAST VICE-PRESIDENT, SOCIETY OF PUBl.IC ANALYSTS ; AND ONE OF THE ORIGINAL FOUNDERS OF THE INSTITUTE OF CHEMISTRY SECOND EDITION NEW YORK D. VAN NOSTRAND COMPANY EIGHT WARREN STREET 1921 Engineering Library There is a lesson in each flower, A story in each stream and bower ; On every herb o'er which we tread Are written words which, rightly read, Will lead us from earth's fragrant sod To hope and holiness and God." PRINfED IN GREAT BRITAIN. PREFACE TO THE SECOND EDITION THE very favourable reception accorded to the first edition of this work has induced me to enlarge its scope, thus permit- ting of the inclusion of many more natural products and manufactured articles and fuller references to a number of subjects which are of special present-day interest and import- ance, such as the Hypothetical ^Ether, Atomic Structure, Catalysis, Colloids, Constitution of Matter, Cottrell Precipita- tion Process, Enzymes, Flotation Process of Ore Dressing, Lubricants, Nitrogen Fixation, Plant Colouring Matters, Radio-activity, Refractories, etc. All criticisms of the original work have received careful attention, and it has been thoroughly revised and brought up to date, many chemical constants being introduced, so that it may be of increased usefulness to practical chemists for reference purposes, without diminishing its value in other respects. In brief, I have endeavoured to make the volume a compendious encyclopaedia of chemical information, of service to professional chemists by reason of its comprehen sive character and scientific accuracy ; useful to merchants, brokers, and all others who have to deal with chemical, manufactured and natural articles ; and, while I am conscious of many imperfections in carrying out what has proved to be a heavy and difficult task, I trust it is qualified by its informative character to find a place in the libraries of all who take an v 481594 vi PREFACE TO THE SECOND EDITION interest in the arts and industries of the British Empire, and the utilization of its boundless resources upon which the future prosperity of that Empire so largely depends. I have, of necessity, culled information from all sorts of sources, including standard works, the publications of scientific societies and the chemical press generally, for which I make grateful acknowledgment, as also to Messrs. John J. Griffin and Sons, John Browning, and L. Oertling, Ltd., for the use of printing blocks illustrative of apparatus. C. T. KINGZETT. "NEWLANDS," WEYBRIDGE. August, 1921 PREFACE TO THE FIRST EDITION IN the compilation of this dictionary, I have attempted to discharge a task which has not, to my knowledge, been pre- viously undertaken, and that is, to give in one volume, in compendious form, and in simple language, descriptions of the subjects of chemistry its laws and processes, the chemical elements, the more important inorganic and organic com- pounds and their preparation or manufacture and applications, together with illustrated descriptions of chemical apparatus. My endeavour has been to produce a popular educational work which will incidentally serve as an advanced companion to my little book entitled " Chemistry for Beginners and School Use" (Bailliere, Tindall and Cox), and as a general work of reference, not only to many practical chemists, but more particularly to that larger body of the public who, in course of their various callings, have occasion to deal or take interest in the thousand and one subjects and substances of which descriptions are given. While abstaining from giving references and quoting authorities, in order to avoid confusion, I gratefully acknow- ledge the use made, in particular, of Newth's " Text-book of Inorganic Chemistry" (Longmans, Green and Co.) Sudborough's translation of Bernthsen's " Textbook of Organic Chemistry" (Blackie and Sons, Ltd.), Watts' viii PREFACE TO THE FIRST EDITION " Dictionary of Chemistry " (Longmans and Co.), and Tilden's most interesting work entitled " Chemical Discovery and Invention in the Twentieth Century" (George Routledge and Sons, Ltd.). Mr. F. G. Clarke, B.Sc., has kindly assisted me in correcting the proof-sheets, and my thanks are due to Messrs. John J. Griffin and Sons, Messrs. Baird and Tatlockj John Browning, and L. Oertling, for the loan of printing blocks illustrative of chemical apparatus. C. T. KINGZETT. " MAPLIN," FRINTON-ON-SEA; November, 1919. CHEMICAL DICTIONARY ABIETIC ACID (C 19 H 28 O 2 ) A constituent of common rosin which crystallizes in small plates, melts at 153 C., and is soluble in hot alcohol, ether, and chloroform. Pimaric acid (C 20 H 30 O 2 ), obtained from galipot (French rosin), melts at 145 C., and nearly resembles abietic acid. ABRASIVES Preparations such as aloxite, carborundum, corundum, emery, kieselgiihr, pumice powder, tripoli, oilstone, and whetstone, used for cleaning or abrading by rubbing. Emery in the raw state comes from the Island of Naxos, in the Greek Archipelago ; silicon carbide, corundum, and corundite are found in South Africa; and an aluminous abrasive is found in the south of France and the Pyrenees. All are used in making grinding- wheels, etc. ABSINTHE A bitter and drink, used in France and Switzer- land, prepared from various species of Artemesia absin- thium (wormwood), which also yield absinthe, or wormwood, oil. The unexpanded flower-heads of another variety (Artemesia vahliana) are the source of santonin. A substance named absinthin (C 40 H 56 O 8 .H 2 O) is said to constitute the bitter principle of wormwood, and is a crystalline body, slightly soluble in water and readily soluble in alcohol. Absinthe oil has a sp. gr. of 0-92 to 0-955; a refractive index of 1-46 to 1*47, and is soluble in alcohol, ether, etc. ABSORBENT The property of absorbing or soaking up. ABSORPTION BULBS See Organic Analyses. ACACIA See Gums. ACANTHITE Natural silver sulphide (Ag 2 S), containing 87 per cent, silver, found in Colorado. ACETALDEHYDE See Aldehydes. ACET AMIDE See Amides.. ACETANILIDE (C 8 H 9 NO), or PHENYLACETAMIDE (C 6 H 5 .NH.C 2 H 3 O) A white crystalline substance known under the common name of " antifebrine," and used as a medicine in fever cases. It is made by boiling aniline with glacial acetic acid. Melting-point, 113 C. /, 5 J {?** .'V a 2 > 2 A " !"* :2lu ACETIC ACID (C 2 H 4 O 2 ) The active principle of vinegar, which contains from 3 to 5 per cent. It is readily pre- pared by the oxidation of ordinary alcohol and the fermentation of alcoholic liquids by a minute organism (Mycoderma aceti). It is also extracted from the products of the dry distillation of wood. (See Pyroligneous Acid.) Pure acetic acid (also known as glacial acetic acid) is a crystalline body of sp. gr. 1*055 which melts at 167 C., boils at 118 C., and is soluble in water and alcohol. What is known as the "quick process" of producing ordinary acetic acid consists in trickling dilute alcoholic liquors over shavings of beech-wood previously coated with "mother of vinegar" that is, a cultivation of the Bacterium aceti at a temperature of 35 C. The souring of thin wines is due to the production of acetic acid by the same micro-organisms, which are always present in the air. , A process for the production of acetic acid from acety- lene is as follows : calcium carbide is prepared by heating lime with coke in an electric furnace, and the acetylene produced from this product is then combined with water, through the agency of sulphuric acid acting in conjunction with mercuric and ferric sulphates, whilst the aldehyde is oxidized by means of oxygen distilled from liquefied air These changes may be expressed as follows : 1. The production of acetylene from calcium carbide CaC 2 + 2H 2 = C 2 H 2 + Ca(OH ) 2 . 2. The hydration of acetylene to acetaldehyde C 2 H 2 + H 2 O = CH 3 .CHO. 3. The oxidation of the acetaldehyde to acetic acid CH 8 .CHO + O = CH 3 COOH. From the acetic acid thus prepared acetone can be pro- duced by the reaction expressed by 2CH 3 COOH = (CH 3 ) 2 CO + C0 2 + H 2 O. (See Acetone.) Acetic acid in its various forms finds large applica- tion in industrial processes, including that of white-lead manufacture, and for technical purposes it is put on the market in liquid forms containing respectively 33, 70, and 80 per cent., etc. (See Wood.) By combination with bases, acetic acid forms the salts ACETIC ACID ACETYLENE 3 ACETIC ACID (Continued) known as acetates, most of which, including all the normal ones, are soluble in water. ACETIC ANHYDRIDE (C 4 H 6 O 3 ) A colourless mobile liquid of sp. gr. 1-082 and suffocating odour, which boils at 137 C. It may be chemically regarded as derived from acetic acid by the abstraction of a molecule of water from two mole- cules of the acid. 2 C 2 H 4 2 -H 2 O = C 4 H 6 3 . It is soluble in alcohol and ether, and resolved by water into acetic acid. ACETIC ETHER See Ethyl Acetate. ACETINE (C 2 H 3 O 2 .C 3 H 5 (OH) 2 ) A colourless, thick liquid of sp. gr. i '22 12; soluble in water, alcohol, and ether; used for gelatinizing smokeless gunpowder and dynamite, etc. ACETONE (C 3 H 6 O or CH 3 OCH 3 ) A mobile, inflammable, colourless liquid of agreeable characteristic odour, obtained, amongst other methods, by the dry distillation of calcium acetate. This method has been brought to a high degree of efficiency, but the reactions involved are complex, and there are many by-products. To produce acetone from acetic acid the latter is vapour- ized and passed through a heated vessel containing a catalyst which effects its decomposition, as expressed above (under Acetic Acid). The products are passed through a hot scrubber containing soda-ash, by which the unchanged acetic acid is arrested, thus forming sodium acetate, the acetone passing on into condensers, from which it is obtained in a 20 per cent, solution. There is also a bio- chemical process for the production of acetone in associa- tion with butyl alcohol from a starchy mass under aseptic conditions, maize being the material chiefly used during the war. It is largely used as a solvent of gun-cotton and celluloid bodies ; boils at 56 C., and has a sp. gr. of 0-81 at o C. Chemically, it belongs to a series of bodies named " Ketones," and it is said to be present in urine in small quantity. (See Acetic Acid and Ketones.) ACETYL CHLORIDE (C 2 H 3 C1O) A colourless mobile liquid which boils at 55 C., and has a suffocating odour. ACETYLENE (C 2 H 2 ) A poisonous hydrocarbon gas pro- duced from calcium carbide by allowing water to drop on 4 ACETYLENE ACIDS ACETYLENE (Continued) that material as contained in a suitable generator, which may be connected with a gas-holder in which the gas can be stored over water CaC 2 + 2H 2 = Ca(OH) 2 + C 2 H 2 . It is soluble in water, alcohol, and acetone. By burning acetylene gas in conjunction with oxygen in blow-pipe form, a very high temperature is attained higher, indeed, than that of the oxyhydrogen flame and it can be effectively used as a means for cutting through armour-plates up to 6 inches in thickness. ACETYLENE TETRACHLORIDE (CHC1 2 .CHC1 2 ) A colour- less liquid of sp. gr. i'582, used as a solvent for greases and waxes. ACIDS By the word " acid " is meant, generally speaking, something that is sour. Vinegar, for example, is acid or sour in character, and contains acetic acid. Acids turn vegetable blue colours into red colours, tincture of litmus a vegetable dye being ordinarily employed for such testings. There are a great number of acids, derived from various sources. All of them contain replaceable hydrogen, so that they may be regarded as hydrogen salts. Hydrochloric Acid is a combination of i part by volume of hydrogen with i part by volume of chlorine, and is repre- sented by the formula HC1. Nitric Acid is a compound of i part hydrogen, i part nitrogen, and 3 parts oxygen by volume, and is represented by the formula HNO 3 . Sulphuric Acid is compounded of 2 parts hydrogen, i part sulphur, and 4 parts oxygen H 2 SO 4 . These are the three best-known inorganic acids, and they are all largely used in commerce and manufacturing operations. Citric Acid (the acid of citrons and lemons), Acetic Acid, Malic Acid (the acid of apples), Tartaric Acid, and Oxalic Acid, are five of the better-known acids from organic sources. These several acids all of which are soluble in water by combination with bases form the corresponding chlorides, nitrates, sulphates, citrates, acetates, malates, tartrates, oxalates, etc., as illustrated by the following typical equations : 2HC1 + Na 2 = 2NaCl + H 2 O. (Hydrochloric Acid) (Sodium Oxide) (Sodium Chloride) (Water) ACIDS 5 ACIDS (Continued) HN0 3 + NaHO - NaNO 3 + H 2 O. (Nitric Acid) (Sodium Hydroxide) (Sodium Nitrate) (Water) H 2 SO 4 + Na 2 CO 3 = Na 2 SO 4 + H 2 O + CO 2 . (Sulphuric (Sodium (Sodium (Water) (Carbon Acid) Carbonate) Sulphate) Dioxide) These acids and some of their compounds are described under their several names. Acids are termed monobasic, dibasic, tribasic, and tetra- basic, according to the number of hydrogen atoms con- tained in them being replaceable by a metal ; thus, acetic acid is monobasic, sulphuric acid is dibasic, and so forth. Organic Acids, like the inorganic series, may be generally described as substances capable of yielding salts by inter- action with metallic or other bases. They are of immense numbers and diverse characters. One series corresponds to the primary alcohols and aldehydes described under these several headings, and is known as the acetic or " fatty acids " series, thus Formic acid (CH 2 O 2 ) corresponds with Methyl alcohol (CH 3 HO); Acetic acid (C 2 H.O 2 ) corresponds with Ethyl alcohol (C 2 H 5 HO); Propionic acid (C 3 H 6 O 2 ) corresponds with Propyl alcohol (C 8 H 7 HO) ; and Butyric acid (C 4 H 8 O ) corresponds with Butyl alcohol (C.H.HO). It will be seen that these acids rise in steps of CH 2 , and they are formed by the oxidation of their corresponding alcohols or aldehydes. Many of the higher members of the series are solid bodies, and most of them are described under their individual names. Fatty acids can be obtained by the catalytic oxidation of petroleums. (See Petroleum.) A second group of acids is the so-called lactic acid (monobasic) series, and a third group is known as the oxalic acid (dibasic) series. Yet another group, styled the aromatic acids, are analogous to the fatty acids. The individual members of these various groups are described under their respective names, so far as they are included in this dictionary. The chemical relationships between the members of the lactic and oxalic series of acids respectively, are shown by the following typical examples : 6 A CIDSA CTINI UM ACIDS (Continued) Carbonic Acid CO }^ Oxalic Acid C 9 O, Glycolic Acid C 2 H 2 O| O Malonic Acid C 3 H 2 O 2 ) O "2^ -"-2^ Lactic Acid C 3 H 4 O \ n Succinic Acid C 4 H 4 O H The phenols and cresols, or so-called tar acids, while, having weak acid characters, stand in a class by themselves and to some extent behave like alcohols. Hydrocyanic acid (HCN) (a member of the cyanogen group of compounds) constitutionally resembles hydrochloric acid, the radical cyanogen (CN) behaving like chlorine as a halogen in this respect and playing the part of an element, so to say, in many of its compounds. ACONITIC ACID (C 6 H 6 O 6 ) A crystallizable substance soluble in water and found naturally in Aconitum napellus, shave- grass, and cane- juice. It is tribasic and can be prepared by heating citric acid (C 6 H 8 O 7 ), thus causing the loss of the elements of water. ACONITINE (CgjH^NOn) A white, crystalline, extremely poisonous alkaloid obtained from aconite root, which melts at 195 C. and is soluble in alcohol and ether. The leaves of Aconitum napellus (Monk's-hood) contain from 0*1 to i per cent, of the alkaloid, which is used medicinally, admixed with chloroform in the form of a liniment, to relieve neuralgia, etc. ACROLEIN (C 3 H 4 O or CH 2 : CH.CHO) A substance of aldehydic character produced by the oxidation of allyl- alcohol (C 3 HgO), and by the distillation of fats. It is a colourless, inflammable, and poisonous liquid of extremely pungent odour, having a violent action on the eyes. It has a sp. gr. of 0-84 ; boils at 52 C. ; is soluble in water, alcohol, and ether. It yields acrylic acid (C 3 H 4 O 2 ) by oxidation, and this upon fusion with alkali breaks up into acetic and formic acids. ACRYLIC ACID See Acrolein. ACTINISM The chemical effects of light, chiefly exercised by the violet rays. ACTINIUM Name of a radio-active substance resembling and being a product of the disintegration of thorium ; obtained from uranium minerals (pitch-blende), but no atomic weight A CT1NI UMA D REN A LIN 7 ACTINIUM (Continued) has yet been assigned to it. Aqueous solutions of its salts slowly evolve hydrogen and oxygen in the proportions in which they exist in water. 1 ' ADAMANTINE "A proprietary brand of fire and alkali proof material for use in sulphur, pyrites, zinc-blende, and other burners. ADDITIVE COMPOUNDS Are those formed, as it were, by mere addition of elements to compounds or of compounds to compounds, instead of by substitution or replacement. For example, ethylene (C 2 H 4 ),an unsaturated hydrocarbon, combines with chlorine, forming ethylene chloride (C 2 H 4 C1 2 ), by direct addition, thus satisfying two spare affinities of the carbon atoms in the ethylene. ADENINE (C 5 H 5 N 5 ) An alkaloidal base found in the pancreas and in a number of vegetable growths, which has also been produced synthetically. ADEPS LAN.32 (Lanoline) A refined wool fat, prepared from " suint," of melting-point about 40 C. (See Suint.) ADHESION The property of holding particles together. ADHESIVES Some varieties of adhesives are made from the proteins or alkali -proteins which are isolated from the residues resulting from the extraction or expression of oils from seeds, and in particular hemp-seed and castor-beans. These are treated with suitable bases, such as the alkaline earth hydroxides, or magnesia, and with an alkali salt (such as sodium fluoride or arsenate), which will react slowly with the bases and form alkali hydroxide, the re- sulting product being then mixed with dilute alkali hydroxide solution. Adhesives are also made from seaweeds, and from various starches and gelatinous bodies, such as gums and glues. (See also Mucilage.) ADIPIC ACID (C 6 H 10 O 4 ) A member of the oxalic series of acids produced by the action of nitric acid upon oleic acid and other fatty acids. It is a solid crystalline body soluble in alcohol, ether, and hot water, which melts at 153 C. ADIPOCERE Fatty matter which is found in dead bodies buried under peculiar circumstances. ADIPOSE (substance) Animal oil or fat. ADEENALIN (C 9 H 13 NO 3 ) A nearly white crystalline sub- stance prepared from the suprarenal glands of sheep and cattle, used in medicine. It melts at from 205 to 212 C., 8 A DRENA UN- A ER1A L ADRENALIN (Continued) and is slightly soluble in water but insoluble in alcohol, ether, and chloroform, and is used in medicine. ADSORPTION This term, in its most general sense, implies the unequal distribution of a substance at the boundary between two heterogeneous phases, and when these concern a solid and a gas it is usually referred to as gas adsorption. Practically, it means the removal or abstraction of a con- stituent of gases or liquids by certain agents, as, for instance, the removal of iodine from a solution of it in potassium iodide by means of charcoal, or, again, the surface action illustrated by the condensation of hydrogen gas by means of palladium (see Occlusion), and the reten- tion of the dark colouring matter of crude sugar solutions, as effected by charcoal during nitration processes. The adsorption compounds, as those of charcoal and caramel, or charcoal and litmus, do not resemble ordinary chemical compounds in constancy of composition and more or less resistance to decomposition by physical agencies, and are generally formed at the surfaces, the quantity being proportional to the active surface. The relative adsorptive powers of various kinds of charcoal depend not merely upon their respective capacities to absorb gases, but also to retain them at reduced pres- sures. It has been ascertained that adsorbents can be prepared from certain colloidal solutions, and silica gel prepared from a colloidal solution of silicic acid is stated to exhibit a power of adsorption equal or superior to that of animal charcoal. It can be prepared from silicate of sodium by the action of a dilute mineral acid, and is stable in the air even at high temperatures. Sulphur dioxide at a concentration of 0'5 per cent, in air, and with a time contact of 0-8 second, is stated to be adsorbed to the extent of 100 per cent., and it is thought in America, where the process has originated, that this new material will prove very valuable in a number of industrial operations for effecting the selective separa- tion of mixed gases and the saving of solvents. (See also Catalytic, Carbon, Enzymes, and Occlusion.) AERATION Charging of liquids with gases. So-called soda- water is water (with or without addition of a little alkali) charged with carbon dioxide gas under pressure. Water can be similarly charged with air or oxygen gas. Many natural sparkling waters are more or less charged with gases. AERIAL Character of air. AEROLITES-AIR (ATMOSPHERE) 9 AEROLITES Meteoric stones reaching the earth through its atmosphere. AETHER See Ether. AFFINITY See Chemical Attraction. AGAR-AGAR A jelly-like preparation, soluble in water, made from certain seaweeds found in the East chiefly of the genus Gelidium (class Rhodophyceae) and used in bacteriological work as a nutrient material for bacterial growths ; also as an adhesive, sizing for silk, and veneering wood. (See also Seaweeds.) AGATE An anhydrous crystalline form of natural silica (SiO 2 ) a variegated chalcedony found in many parts of the United States and elsewhere. AIR (ATMOSPHERE) The air is a mixture of gases. Many years ago it was found that animals which were confined in a limited amount (volume) of air died after a short time. Later, it was ascertained that, in breathing, animals do not consume (use up) all of the air which is inspired (breathed in), but only a part of it, and that part is now known as oxygen ; the other chief part, known as nitrogen, is of no direct use for sustaining life. Air is substantially a mixture of oxygen gas (about 21 parts) and nitrogen gas (about 79 parts). It really contains small quantities of other gases, also varying proportions of moisture (water) in consequence of the evaporation of water from the land and water surfaces of the earth which is always going on. For any given temperature, there is a maximum amount of water vapour which a given volume of air is capable of taking up or dissolving, and under these conditions it is saturated with moisture at that particular temperature. Instruments which have been devised for determining the amount of moisture contained in a given volume of air are termed hygrometers. A cubic metre of air at 20 C. can take up 17 -157 grms. of water, but at o C. it can only hold 4-87 grms., so that when cooled, the excess of water held in gaseous solution is deposited as mist, dew, rain, hail, or snow. As will be seen under the description of oxygen, that gas can be prepared in the laboratory by a number of methods, but it is a natural constituent of the air, the composition of which is materially the same throughout the world. Animal life could not exist if this oxygen gas were not present in the air, and the most interesting point is that the air contains such a much larger quantity of the other gas nitrogen. In breathing the act of inspiration the oxygen io AIR (ATMOSPHERE) AIR (ATMOSPHERE) (Continued) of the air is sucked up or absorbed in the lungs, and that reacting upon the blood forms carbon dioxide, which gas is given out in the breath the act of respiration. The inert nitrogen which is present in the air makes the oxygen weak or dilute enough to enable this to be done, as oxygen is fatal to human life when continuously breathed in its pure state. It is the oxygen of the air that also sustains the com- bustion of wood, coal, and coke in fire-grates. In burning, the carbon of which coal and coke are largely composed combines or enters into chemical combination with the oxygen of the air, forming carbon dioxide, and gives out heat at the same time. Charcoal is a form of carbon, and if a piece of it be heated to redness and then placed in a globe or glass jar containing oxygen gas, it becomes much brighter in redness, much hotter, and gradually disappears, being burnt up (consumed) and thereby converted into carbon dioxide by combining with the oxygen. This act of burning, or combustion as it is termed, is essentially dependent upon the presence of oxygen. If an ordinary night-light be lighted and placed in a wide- mouthed stoppered bottle, and the bottle then closed, the night-light will go on burning until the oxygen contained in the air present in the bottle has been used up, when it will go out. On the other hand, as is well known, it will go on burning in the open air until it is all consumed. The air always contains a certain quantity of carbon dioxide, and this constituent is of more importance than might appear without careful consideration, bearing in mind how essential it is to the growth and development of vegetable life, and how the quantity of oxygen contained in the air is maintained by way of compensation. It has been estimated that the amount of carbon dioxide given off in each twenty-four hours through the lungs of an adult human being is that which results from the oxidation of between 7 and n ounces of carbon, and this necessitates the consumption of about i| pounds of oxygen gas inhaled ; and if now we multiply this quantity by the number of the world's inhabitants (human beings and animals), the amount of oxygen gas thus removed from the air is represented by an astounding figure. The quantity, indeed, is so large that, unless there existed some compensating process, life would in course of time become impossible on the earth. It is now known that plant life gives back to the atmosphere the oxygen which animal life removes from it. This is the more important because, AIR (ATMOSPHERE) AIR-PUMP n AIR (ATMOSPHERE) (Continued) whereas 100,000 parts of air ordinarily contain about 33 parts by volume of carbon dioxide, larger proportions would foul it to such an extent as to produce headache and other sickness, while the presence of from 200 to 300 parts is seriously prejudicial to health. Vegetable life absorbs carbon dioxide from the air, as also from decomposing organic matter in the soil, and, assimilating the carbon in its tissues by a variety of chemical processes, gives out again the oxygen which is contained in it, and thus maintains the composition of the air practically constant and universal. The immensity of this process can be imagined when we reflect upon the vast extent of forestry and plant life which covers the surface of the earth, and makes us realize at the same time the great importance of carbon dioxide as a constituent of the air side by side with that of oxygen and nitrogen, its other chief constituents. (See Vegetation.) The air of towns generally contains small proportions of ammonia, sulphur dioxide, sulphuretted hydrogen, and organic matters, whilst nitric acid is produced by lightning flashes. At times, ozone in small proportion also forms an aerial constituent, particularly in the upper layers, whilst recent investigations have revealed the presence, as normal constituents, of a number of rare gases in minute quantities including argon, helium, neon, krypton, and xenon. The relative proportions in which these are present are shown below : Argon 0*937 P art m 100 air Helium i part in 250,000 air Neon i to 2 parts in 100,000 air Krypton i part in 1,000,000 air Xenon ... ... i part in 20,000,000 air The weight of a litre (1,000 c.c.) of air at o C. and 760 mm. of pressure is 1*2932 grms. Its constantly vary- ing pressure can be registered at the earth's surface by means of the barometer. (See Barometer.) AIR-PUMP A mechanical appliance provided with valves used for pumping air into or withdrawing (exhausting) it from a vessel. The hand and foot pumps used for pumping up cycle tyres are illustrative, whilst an ordinary syringe is useful for many purposes, although it has not any valves. Amongst other applications, air-pumps are used in labora- tories in association with desiccators for evaporating opera- tions conducted at the ordinary temperature, of the atmosphere. This is done in order to reduce the atmo- 12 AIR-PUMPALBUMINS AIR-PUMP (Continued) spheric pressure and thus promote the evaporation from the containing vessel, and at the same time to remove the aqueous vapour coming from the substance being desiccated (dried) in the partially vacuous space, which may not already have been absorbed by any appliance placed therein for that purpose. (For illustration, see Desiccator ; see also Pumps.) A JO WAN OIL From the seeds of Carum ajowan, which yield about 3 to 4 per cent, of sp. gr. from 0-900 to 0-930. (See Thymol.) ALABASTER A native form of fine-grained gypsum or calcium sulphate (CaSO 4 ), used in sculpture and for orna- mental applications. ALBUMINOMETER (Esbach's) A graduated tube about 6 inches long and J inch diameter, graduated so that each degree indicates o-i per cent, of albumin. The tube is filled to a given mark with urine, and a reagent of i per cent, picric acid and a 2 per cent, solution of citric acid in distilled water is then added up to another mark. This causes the precipitation of any albumin contained in the urine, and after settlement the volume is read off by the graduations on the tube. ALBUMINS Substances constituting one of the principal divisions of the larger group of so-called albuminoids or " proteins " which make up the chief part of the flesh of animal organisms and are contained in plants, especially in the seeds. They are uncrystallizable nitrogenous bodies of complicated composition containing : Carbon from 52-7 to 54-5 per cent., Hydrogen from 6*9 to 7-3 per cent., Nitrogen from 15-4 to 17*6 per cent., Oxygen from 20-9 to 23-5 per cent., and Sulphur from o'8 to 5^0 per cent. Some are more or less soluble in water, but all are soluble in dilute alkaline and saline solutions, and are precipitated therefrom by alcohol. When their solutions are heated they become coagulated. These albuminoids are changed by mild processes of hydrolysis, as induced by the action of dilute acids or alkalies, as also by the enzymes which take part in the processes of digestion, into so-called albumoses or peptones, and when the hydrolysis is carried still further, a variety of products result, ultimately terminating with a number of substances A LB UMINSA LCOHOLS ALBUMINS (Continued) termed amino-acids, one of the best known of which is tyrosine. (See Polypeptides.) The putrefaction of albumins gives rise to the production of many derivatives, including some alkaloidal substances called ptomaines or toxines, which are highly poisonous, and two of which have been isolated viz., " putrescine " and " cadaverine " and their chemical constitutions determined. Acted upon by the stomachic secretions, albuminoids are converted into peptones, which are soluble in water and become available for assimilation. The white of egg is a typical albumin, of which large quantities are used in France for the clarification of wines. (See also Blood Albumin, Casein, and Proteins.) ALBUMOSES See Albumin and Proteins. ALCOBRONZE See Copper. ALCOHOL Spirits of wine, of indefinite alcoholic strength. (See also Methylated Spirit and Proof Spirit.) ALCOHOL TABLE, SHOWING THE SPECIFIC GRAVITIES OF VARIOUS STRENGTHS. Absolute Alcohol Absolute Alcohol per Cent. S.G. at 15-5 C. per Cent. S.G. at 15-5 C. by Volume. by Volume. I 9985 55 9242 5 9928 60 9134 10 9866 65 9020 J 5 9810 70 8899 20 9760 75 8772 25 9709 80 '8637 3 9654 85 8494 35 '959 1 90 8337 40 9518 95 8i59 45 '9435 100 7939 50 '9343 (See Absolute Alcohol and Fermentation.) ALCOHOLS Ordinary Alcohol (Ethyl Alcohol) is only one of a series of homologous alcohols of ascending specific gravities and boiling-points, the lower members being colourless mobile liquids, the middle ones of more oily character, and the 14 ALCOHOLS ALCOHOLS (Continued) higher ones solid, like paraffin in appearance and without taste or odour. Some are found in nature in combination with organic acids in essential (ethereal) oils and waxes. Methyl Alcohol, CH 3 OH (or CH 4 O), is contained in combination with salicylic acid in oil of wintergreen, and is found among the products of the distillation of wood. It is a limpid, colourless, volatile liquid which boils at 66 C., has a sp. gr. of 0*8, burns with a non-luminous flame, and is a solvent of fats and oils. It is soluble in water, and is used commercially in making spirit varnishes, polishes, and for " methylating " spirits of wine. Upon oxidation, it yields formaldehyde (CELO), and finally formic acid (CH 2 2 ). Ethyl Alcohol (Absolute Alcohol or Grain Spirit) (C 2 H 5 OH or C 2 H 6 O) is a limpid, colourless, volatile, inflammable liquid which boils at 78-3 C., and has a sp. gr. of 079. By oxidation, it is converted into acetaldehyde (C 2 H 4 O), and finally acetic acid (C 2 H 4 O 2 ). It is the pro- duct of the fermentation of sugar (glucose), and the intoxi- cating principle of wines, beers, and spirits (gin, whisky, brandy, and rum). (See Wines.) Alcohol is prepared commercially from the starches of cereals or potatoes or from sugar by processes of fermenta- tion. The starches are first of all converted into maltose by the action of malt, or otherwise saccharified, the extract or " wort " being then subjected to fermentation as in brewing, and subsequently distilled in order to obtain the alcohol thus produced. This process of fermentation has been applied to the waste sulphite liquors resulting from pulp production. (See Paper.) In the Philippine Islands, alcohol is made on a com- mercial scale from the sap of the Nipa palm, although the production of sugar from that source is at present only in the experimental stage. Alcohol is also made to some extent from wood-waste and sawdust by conversion of their cellulose contents into saccharoids and subsequent fermentation. Pine- wood saw- dust is stated to give the best result, yielding not less than 12 per cent, calculated on the dry sawdust. The " Amylo " process carried on near Lille depends upon the use of certain moulds, such as the Asptrgttlac&f, for saccharifying starch instead of malt the Rhizopus delemar or Mucor boulard being now almost exclusively employed thus avoiding the formation of the unfer- mentable dextrins which result to some extent when malt ALCOHOLS 15 ALCOHOLS (Continued) is used. The yeast used for fermenting the material thus prepared exercises its optimum effect at 38 C., and the process, which takes in all, four days to complete, yields up to 97-5 per cent, of the alcohol theoretically obtainable. Attempts have also been made to produce ethylic alcohol from the ethylene contained in coke-oven gases by absorb- ing it in 95 "per cent, sulphuric acid and hydrolizing the ethyl sulphate thus produced by dilution of the acid mixture with water or steaming, thus producing alcohol, which is recovered by distillation and regenerating the sulphuric acid. Of course the gas, prior to this procedure, is freed from tar, ammonia, naphthalene, benzol, sulphuretted hydrogen, the higher defines, and water vapour in the order as here given. It is on record that 1*6 gallons of alcohol can be thus obtained from each ton of the particular Durham coal employed. Alcohol is soluble in water, and is largely used as a solvent, in the manufacture of explosives, chemicals, perfumes, lacquers, pharmaceutical extracts and tinctures ; also as a fuel, in the compounding of drinks, and for pre- serving anatomical specimens. Although its calorific value is not much more than one half that of petrol, its efficiency is much greater owing to its relatively greater combustion. It can be compressed to a greater extent, and this property of high-ignition temperature under compression is not materially altered by admixture with 20 per cent, benzene or petrol. Such a mixture readily starts in the cold and runs smoothly ; so that if alcohol could be manufactured sufficiently cheap it would become a serious competitor with petrol as a motor fuel. Propyl Alcohol (C 3 H 7 OH or C 3 H 8 O) is a spirituous colourless liquid which can be obtained from fusel oil. It boils at 97 C., and has a sp. gr. of 0-806. By oxidation it yields propylaldehyde (C 3 H 6 O), and finally propionic acid (C 3 H 6 2 ). Butyl Alcohol (C 4 H 9 OH or C 4 H 10 O), a limpid, colour- less liquid which boils at 117 C., has a sp. gr. of 0-824, and by oxidation yields butyric acid (C 4 H 8 O 2 ). It is used to some extent in making fruit essences. There are further members of this class of so-called monohydric or aliphatic alcohols, including amyl alcohol (C^OH), hexyl alcohol (C 5 H 13 OH), and heptyl alcohol (C r H 15 OH) ; in addition, there are other series of alcohols i6 ALCOHOLS ALDEHYDES ALCOHOLS (Continued} - viz., the dihydric alcohols or glycols, and the trihydric alcohols, of which ordinary glycerine is a member. The glycols include ethyl glycol (C 2 H 6 O 2 or C 2 H 4 ,2HO), propyl glycol (C 3 H 8 O 2 or C 3 H 6 ,2HO), and butyl glycol (C 4 H 10 O 2 or C 4 H 8 ,2HO), and so forth. They are mostly thickish liquids of somewhat sweet taste, readily soluble in water and alcohol. Of the trihydric alcohols, or glycerines, glycerol or ordinary glycerine is a member and illustrative, its formula being C 3 H 8 O 3 or C 3 H 5 ,3HO. (See Glycerine.) The commercial article known as Alcohol Solidified is really a mixture of alcohol, or alcohol and methylated spirit, with soap. One formula is alcohol, 60 parts ; methylated spirit, 40 parts ; and sodium stearate, about 3 parts. ALDEHYDES constitute a series of organic bodies (mostly liquids) related to the alcohols and the ethers, and are formed as first products of the oxidation of the alcohols by the elimination of two atoms of hydrogen therefrom (C 2 H 5 HO less H 2 = C 2 H 4 O). This relationship is illus- trated by the following equation in the case of ethyl alcohol, C 2 H 5 HO+O = C 2 H 4 O + H 2 O. By further oxi- dation, the aldehydes so produced are converted into a corresponding series of acids ; thus ethyl aldehyde becomes oxidized to acetic acid, C 2 H 4 O + O = C 2 H 4 O 2 . The lower members of the aldehydes are neutral volatile liquids of characteristic odour, soluble in water, with lower boiling-points than those of the corresponding alcohols. These aldehydes are easily reconverted into their cor- responding alcohols by the action of nascent hydrogen ; thus the ethyl or acetic aldehyde is changed back to ethyl alcohol, as shown in the equation, C 2 H 4 O + H 2 = C 2 H 5 HO. This can be realized, for example, by passing its vapours with hydrogen gas over finely divided copper or nickel at 120 to 300 C. With copper the yield is 87-6 per cent, at 200 C. It is the Ethyl Aldehyde (CH 3 CHO) that is commonly known as acetaldehyde or aldehyde, and it is ordinarily prepared by the oxidation of ethyl alcohol by means of potassium dichromate or manganese dioxide and sulphuric acid. It is a colourless, mobile, inflammable, volatile fluid of a peculiar pungent odour, boiling at 22 C., and of sp. gr. 0-801, miscible with water, alcohol, and ether, ALDEHYDES ALIZARIN 17 ALDEHYDES (Continued) and possesses strong reducing properties (see Reducing Agents). Apart from its chemical applications, it finds use as a solvent and as an antiseptic inhalant in cases of nasal catarrh and ozaena. It is otherwise known as "ethanal." Methyl Aldehyde (CH 2 O), the next lower member of the series, is, in its normal state, an exception to the rule above stated, being a gas, and is produced as described under Formaldehyde, which is the common name for it : CH 3 HO (methyl alcohol) + O = CH 2 O + H 2 O. It is otherwise known as " methanal." (See Formaldehyde and Paraform.) ALEMBROTH (SALT OF) A crystalline compound of mercu- ric chloride and ammonium chloride (2NH 4 Cl,HgCl 2 ,H 2 O), prepared by mixing solutions of the two salts in suitable proportions. ALG^E An order of flowerless plants, including the sea- weeds (fucus) and the fresh-water confervas. (See Sea- weeds.) ALGIN A gelatinous (albuminous) material, being a sodium salt of alginic acid, obtained from seaweeds, which finds some industrial applications, and can be used as a food. It is obtained by soaking the marine algae for twenty-four hours in a i per cent, solution of sodium carbonate, filtering the viscous liquor through cloth, and precipitating it there- from by dilute sulphuric acid, washing, and drying. The compounds of algin give very viscous solutions, and are valuable as sizings for textiles and paper, as thickenings for printing colours, and as proofings for interior walls and ceilings. The sodium compound is soluble in water, and a 5 per cent, solution is so viscous that it can hardly be poured out from its containing vessel. The heavy metallic compounds are insoluble in water, but some are soluble in ammonia, and these solutions are used as waterproofing materials for textiles. ALIZARIN (C 14 H 8 O 4 or C 6 H 4 (CO) 2 C 6 H 2 (OH) 2 ) An im- portant colouring matter, prepared from the roots of the madder plant (grown largely in Alsatia), and now made on an extensive scale by a synthetic process from anthracene. It is contained in the red dye of madder root (Rulia tinctovum) in the form of a glucoside. 18 ALIZARIN ALKALI TRADE ALIZARIN (Continued) crystallizes in fine red prisms and needles, which melt at 289 C ; is sublimable, and soluble in alcohol and ether, but only to a small extent in water. With metallic oxides it gives very fine " lakes '' of varying hues, and is used in making dyestuffs. ALKALI METALS See Bases. ALKALI TRADE- CHART SHOWING THE PROCESSES EMPLOYED. and Soda Nitre (NaNO 3 ) From Iron Pyrites (Sulphide of Iron, FeS) there are produced: Burnt Ore and from which are extracted Sulphuric Acid, which is used Iron Copper Silver and Gold. to act upon Common Salt (NaCl) making I to act upon Magnesia to make Epsom Salts (MgSOJ. Hydrochloric Acid (HC1), which is used with Man- ganese Ores to make and Sulphate of Sodium (Na 2 SO 4 ), from which is produced | I 1 Chlorine Gas, M a n g an- Carbonate of and which is ese Chlor- Soda(Na 2 CO 3 ), ' ' Alkali waste, ' used to ide (MnCl 2 ) from which from which make (from which also Caustic the Sulphur the Mangan- Soda (NaHO^ is recovered. ese is re- is made. covered as Oxide and used over again) and Calcium Chloride (CaCy. Bleaching Powder (Chloride of Lime). Potassium Chlorate (KClOg). ALKALI TRADE ALKANET 19 ALKALI TEADE (Continued) In 1869 it was estimated that the total quantity of salt decomposed in Great Britain for the production of soda was 326,000 tons. ALKALI WASTE The residual matter or by-product from the manufacture of sodium carbonate by the old (Leblanc) process. For every ton of soda ash produced there are from one and a half to two tons of waste. Many processes have been devised for the extraction or recovery of the sulphur it contains in combination with calcium viz., 15 to 20 per cent. and of these the most important is the " Chance " process, which, however, is applicable only to recently made waste as distinct from the old accumu- lated masses lying in manufacturing areas, and which rapidly undergoes chemical changes by atmospheric action. (See Sodium and Sulphur.) ALKALIES See Bases. ALKALINE EAETH METALS See Bases. ALKALOIDS A nitrogenous class of organic substances (bases), viewed by some as built up or derived from amino-acids. They are basic or alkaline in character, and may be regarded on the whole as compound ammonia bodies, resembling ammonia, as many of them do, in forming definite or crystalline salts with acids, and in other respects. They are individually described under their several names. The vegeto-alkaloids occurring in plants, in contra- distinction to those derived from animal sources (such as cadaverine), constitute an important group of compounds by reason of their physiological properties, and are the active principles of many drugs. As they exist in plants they are, for the most part, in combination with acids such as citric, malic, tannic, and quinic acids, and comprise quinine and the other associated alkaloids (see Opium), atropine, berberine, brucine, codeine, coniine, hyoscya- mine, morphine, nicotine, papaverine, pilocarpine, solanine, strychnine, etc. As a class they are bitter compounds of poisonous character, and are usually extracted from the plant tissues containing them by infusion with acidified water. (See also Amines.) ALKANET An ancient dyestuff in the form of a dark red amorphous powder, prepared from the roots and leaves of the shrub Lawsonia inermis. It exhibits a green iridescence, 20 ALKANET ALLOYS ALKANET (Continued) and is used in the East for dyeing the nails, teeth, and hair, as also garments. ALKYLENES The divalent residues (C n H 2n ), such as the defines. ALKYLS The monovalent groupings, such as methyl and ethyl, which form the radicles of the monovalent alcohols. ALLANITE A natural complex silicate. (See Lanthanum.) ALLOPEANE A mineral hydrated aluminium silicate. ALLOTROPY The property of assuming various distinct forms. Oxygen and ozone, for example, are allotropic forms of the same substance. Again, carbon is known in the forms of the diamond, graphite, and charcoal. Sulphur and phosphorus are also known in several distinct forms. It has been conjectured that allotropy is to be attributed to the varying number of atoms contained in the molecules of the various substances capable of assum- ing allotropic forms. ALLOXAN (C4H 2 N 2 O 4 ) A derivative of uric acid, which yields urea by the action of barium hydroxide. ALLOYS Many metals when melted together have the pro- perty of combining with each other to form either mixtures or definite compounds called alloys, a number of which are very useful in the arts and manufactures. At least some of these mixtures may be regarded as solutions of definite com- pounds in an excess of one of the metals employed, and may, therefore, be considered as solidified solutions. In this way, the metals aluminium, zinc, iron, tin, copper, and lead are largely used, and sometimes mercury, silver, gold, and platinum. So-called German silver is a mixture of copper, zinc, and nickel; and brass consists of about 2 parts copper and 1 part zinc. The British gold coin consists of pure gold 22 parts, and 2 parts alloy of silver and copper, and, until recently, silver coins consisted of 92^ parts silver and yj parts copper. Descriptions of various alloys will be found under the headings of the metals used in compounding them, and some of the better-known ones are shown in tabulated form on the opposite page. Some alloys can be obtained in crystalline forms in which the combined metals are associated in atomic pro- portions. ALLOYS 21 ALLOYS (Continued) An alloy of 85 per cent, lead and 15 per cent, magnesium when exposed to moist air undergoes rapid oxidation, swelling up and falling to a black powder in course of a few hours, the interactions being expressed as follows : (a) Mg +0 + H 2 O = Mg0 2 H 2 . (b\ 2Pb + O + H 2 O=PboO 9 H 2 . \ / 2 222 This alloy decomposes water, liberating hydrogen, and particularly so w r hen the proportion of magnesium is increased to 30 per cent. a . o , ' 1 d _c d o 1 1 "3 1 CJ N r^ d 2 "* .2 u < Muntz metal 3 I __ Yellow brass 66 33 Britannia metal (a) 3 140 9 it (&) 4 84 10 2 Bell metal 80 20 Bronze (for statues) 91-4 5*53 1-7 r 37 ,, (for cannon) 90*0 lO'O German silver 50 25 25 Type metal 5 20 75 Stereotype metal ... 3 18 112 Pewter 4 I Wood's fusible metal I i 2 4 Aluminium is extensively used in making a number of alloys with copper, of which magnolium in several varieties contains from 10 to 30 per cent, of magnesium also. It is silver-white, strong, ductile, and easily cast, having a sp. gr. of from 2 to 2'5. When 10 per cent, magnesium is present, the alloy has a melting-point of from 650 to 700 C. Alloys of aluminium and magnesium of the compositions Al 3 Mg 2 and Al 2 Mg 3 have been described, and other mag- nesium alloys adapted to special applications are made containing small percentages of manganese, nickel, lead, tin, and iron. Evidence has also been forthcoming of the existence of definite alloys of copper with zinc and tin respectively having the formulae CuZn 3 and Cu 3 Sn. Soldering consists in fusing together the surfaces of the 22 ALLOYSALUMINIUM ALLOYS (Continued) same or different metals by means of an interposed alloy which must be more fusible than the two metals to be joined, and have an affinity for both of them. (See also Ferro- Alloys.) ALLSPICE OIL (oil of pimenta) A colourless or somewhat yellow oil, distilled from the fruit of Pimenta officinalis, which darkens and thickens upon exposure to the air, and has a clove-like odour. It has a sp. gr. of from 1*02 to 1*05, refractive index about 1*53, is soluble in alcohol and ether, and is chiefly used for flavouring. ALMOND OIL Bitter almond oil is extracted by maceration and distillation from the ripe seeds of Amygdalus communis, which is cultivated in Italy, Spain, and the south of France, thus yielding about 40 per cent, of yellowish oil of sp. gr. 1-045 to 1*070, with refractive index of 1-54. It is soluble in alcohol and ether, and is used for flavouring purposes. Its fragrant odour is due to benzaldehyde (C 7 H 6 O), which is not contained in the original oil, but is produced during the maceration by the action of the enzyme named emulsin on the amygdalin contained in the fruit. (See Amygdalin.) Sweet almond oil is obtained by expression of the same seeds. It has a yellowish colour, is aromatic, has a sp. gr. of 0-915 to 0*920, consists mainly of olein, and is used in perfumery and as a delicate lubricant. ALOES (bitter aloes) The inspissated juice of various species of the aloe, containing aloin and used in medicine. Barbadoes aloes comes from the leaves of Aloes vulgaris, and is a dark-coloured, resin-like substance ; Cape aloes, from A loe ferox, A . africana, and A . spicata, is used both in medicine and dyeing. ALOIN (C 17 H 18 O 7 ) A yellow crystalline substance extracted from Barbadoes aloes, little soluble in water and alcohol but soluble in formamide and alkalies. Used in medicine. ALOXITE (aluminium oxide, A1 2 O 3 ) Prepared by fusion of bauxite and sold as an abrasive. ALUMINIUM (Al) (atomic weight, 27 ; sp. gr. 2-58 ; melting- point, 658 7 C.) Aluminium is found very abundantly in nature in a state of combination, but not in the metallic state. Combined with oxygen as alumina (A1 2 O 3 ), it forms the substance of the precious stones known as the sapphire and ruby, both of which are now produced commercially by the fusion of pure alumina in a specially constructed electric ALUMINIUM 23 ALUMINIUM (Continued) furnace, and are as good in all respects as the natural gems, with which they are identical in composition and properties. In combination with silica, aluminium exists as clay, and in another form of combination with iron oxide, it is found in the mineral known as bauxite (A1 2 O 3 ,H 2 O), from which it is chiefly manufactured by an electrical process. Alumina prepared from bauxite and dissolved in fused cryolite (a double fluoride of aluminium and sodium) is subjected to electrolysis in iron pots lined with carbon, carbon rods being used to carry the current, the power used for generating the electric current (by dynamos) being that of falling waters as utilized at Niagara, the falls of the Rhine at Schaff- hausen, and Kinlochleven in Argyllshire. In this way, the aluminium oxide is decomposed, the melted metal collect- ing at the bottom of the pots and oxygen being liberated at the carbon poles. The total output of aluminium in the year 1909 was estimated at 30,000 tons. The metal is extremely light, being about one-third the weight of iron, and is of the colour of tin. It is very malleable, ductile, does not tarnish when exposed to the air, is a good conductor of electricity, and is extensively used in the construction of many articles both for manu- facturing and household employment. Aluminium powder mixed with oil is also used as a paint for iron exposed to the air. When combined with copper, it makes an alloy known as aluminium bronze, which makes good castings. This bronze is manufactured by heating a mixture of alumina in the form of corundum with charcoal and granulated copper in an electric furnace, in which process the carbon is burned out of the mixture by the oxygen of the alumina (A1^O 3 ), and the copper combines with the metallic aluminium, forming the alloy. The so-called "true bronzes" contain from 3 to 5 per cent, aluminium. An alloy of 85 per cent, aluminium, 12-5 per cent, zinc, and 2-5 per cent, copper has proved very successful for general castings, crank cases, pump-bodies, carburettors, etc. Aluminium has been used in the construction of zeppelins, and alloyed with various other metals it can be usefully employed where lightness combined with strength are desirable qualities. In the form of powder it finds use as an ingredient of certain explosives (see Ammonal) and in the " thermit process," while it is also largely employed in the metallurgy of other metals. 24 ALUMINIUM COMPOUNDS ALUMINIUM (Continued) Corundum, a nearly pure natural oxide of aluminium, occurs in crystallized form, hard enough to cut glass ; it is now made by an electric process on a considerable scale, and is largely used for polishing purposes. Aluminium is the essential constituent of the salts or compounds known as alums, which have important applica- tions in the industries of dyeing and calico printing. Aluminium Oxide or Alumina (A1 2 O 3 ) is used as a mordant in dyeing and calico printing owing to its property of forming insoluble compounds known as "lakes" with vegetable colours, thus fixing them in the tissues under- going treatment and making them washable or " fast." In hydrated form it can be prepared by adding ammonia to a solution of alum, as a white precipitate (A1 2 O 3 .3H 2 O), which can be rendered anhydrous by drying and heating. A dry process for the preparation of alumina involves furnacing bauxite with soda, and subsequent extraction of the aluminate by leaching with water, and a wet process in which the mineral is first heated under pressure with a solution of caustic soda. From these solutions the alumina is obtained by two several methods. In the one, carbon dioxide gas is blown into the solution, thus precipitating the A1 2 O 3 , and, in the other, the solution, after dilution, is stirred with a small quantity of hydrated alumina, in which case a large proportion of the alumina in solution is precipitated, leaving a liquid which, after concentration, is used for attacking a fresh quantity of bauxite. In another process, known as the " Serpek," or " nitride," bauxite, carbon (coal), and nitrogen are made to react at a high temperature (1,700 to 1,800 C.), and the aluminium nitride thus produced yields sodium aluminate upon treat- ment with sodium hydroxide, ammonia being incidentally obtained as a by-product. From this, pure alumina can be readily produced ready for the application of the electrical process for production of the metal. A process has recently been used in Norway for pro- ducing alumina from this mineral by leaching with a 30 per cent, nitric acid solution, which dissolves the aluminium, calcium, and part of the iron contents, leaving the silica and the rest of the iron undissolved. The iron is then removed, the solution evaporated to dryness, and the residue heated to such an extent that the aluminium salt only is decomposed. The nitrogen oxides driven off in this operation are recovered as nitric acid, and the alumina is ALUMINIUM COMPOUNDS 25 ALUMINIUM (Continued) employed for the manufacture of the metal and its various compounds. Aluminium Chloride (A1C1 3 ) is a white volatile solid sub- stance produced by heating powdered metallic aluminium, or a mixture of alumina and charcoal, in a current of chlorine. It was at one time used for the manufacture of the metal. The hydrated salt is A1C1 3 .6H 2 O, and both are soluble in water and alcohol. Aluminium Sulphate (Al^SO^glSHgO) constitutes the natural minerals aluminite and hair-salt, and large quantities are manufactured by dissolving the mineral bauxite in sulphuric acid and purifying the product from associated iron impurities which would interfere with its applications in the dyeing and other industries. It is soluble in water. Aluminium Nitrate (A1(NO 3 ) 3 ), in anhydrous and hydrated forms, is a white crystalline body, soluble in water, used in the textile and leather industries. Alums are double sulphates, the most important of which is the so-called potash alum or ordinary alum of commerce. Potash alum or aluminium potassium sulphate (A1 2 SO 4 ) 3 , K 2 SO 4 ,24H 2 O) is a colourless crystalline efflorescent salt, made on a large scale by mixing the two sulphates and allowing the compound to crystallize out of solution. In a form known as " Roman alum " it is also prepared by dis- solving calcined alumstone (alunite) in water, which leaves alumina undissolved ; or calcined alumstone can be dis- solved in sulphuric acid, and the solution admixed with the proper proportion of potassium sulphate. There is a further process by which it can be produced from a bituminous mineral known as alum shale. Alum is extensively used in the dyeing and calico-printing industries. It is readily soluble in water, and when heated in the dry state melts in its own water of crystalliza- tion, which is gradually expelled, and when the process is carried to a dull red heat a white mass of so-called burnt alum is left. Ammonia Alum or Aluminium Ammonium Sulphate a compound containing ammonium in place of the potassium of ordinary alum is manufactured on a considerable scale, using ammonia (as prepared in gas-works) and sulphuric acid in conjunction with the burnt alum shale already referred to. This shale contains iron pyrites (FeS a ), and 26 ALUMINIUM COMPOUNDS AMALGAM ALUMINIUM (Continued) when roasted in air, the sulphur is to some extent oxidized to sulphuric acid, which combines with the alumina. Ahuninic Acetate ( A1 2 (C 2 H 3 O 2 ) 3 ) , or so called ' < red liqueur, " in solution is used as a mordant in calico printing and dyeing, also for waterproofing cloth, etc. ALUMINIUM BRONZE See Aluminium. ALUM (CHROME) or Potassium Chromium Alum has the formula K 2 SO 4 ,Cr 2 (SO 4 ) 3 24H 2 O, and is prepared by the addition of sulphuric acid to potassium dichromate (K 2 Cr 2 O 7 ) dissolved in water and then reducing it by the passage of sulphur dioxide gas, with the result that the two sulphates of potassium and chromium are left in solution and the so-called alum can be crystallized out therefrom in the form of dark plum-coloured octahedral crystals. It is used as a chrome tanning material, and in the textile industry as a mordant. ALUM SHALE See Aluminium. " ALUMINO -FERRIC " A mixture of crude sulphates of iron and aluminium used as a precipitating and clarifying agent in the treatment of sewage and refuse liquids. ALUMS See Aluminium. ALUNITE or ALUMSTONE A natural, greyish, hydrated basic potassium alum (A1 2 (SO 4 ) 3 ,K 2 SO 4 ,2A1 2 O 3 ,8H 2 O) found at Tolfa and elsewhere in Italy, in the United States, etc. ALLUVIAL ACTION The action of water and air on rocks, attended with the formation of mineral deposits. (See Clay.) AMALGAM The name given to any combination of other metals with mercury. Gold and lead, for example, are both somewhat easily dissolved by liquid mercury in varying proportions ; such combinations, however, are probably not definite chemical compounds, but mere mixtures. The potassium and sodium amalgams decompose water, giving off hydrogen, and are frequently used as reducing agents. An amalgam composed of 25 per cent, zinc, 25 per cent, tin, and 50 per cent, mercury is used as a dental cement, and in the construction of electrical machines. Amalgams of gold and copper are also used by dentists as stoppings for teeth, and tin amalgam is employed for silvering mirrors. There is a native amalgam of mercury and silver in which the proportion of silver ranges from 2 7 '5 to 95*8 per cent., and a native gold amalgam con- AM ALGA MA MIDES 27 AMALGAM (Continued) taining from 39 to 42-6 per cent, is found in California and Colorado. AMATOL See Explosives. AMBER or SUCCINITE (C 10 H 8 O) A yellow, resin-like com- bustible substance of probably vegetable origin, found upon some sea-shores, including the Prussian coast, an'd as a fossil from the extinct conifer Pinus succinifer (Goppert) in certain alluvial soils. Its usual position is in beds of brown coal formation of lower Tertiary Age. It becomes electri- fied by friction, and finds use in the construction of pipe mouthpieces, the bowls of Turkish pipes, and amber neck- laces. It is also used to some extent in the preparation of amber varnishes and amber spirit- varnishes. It contains from 3 to 4 per cent, succinic acid, and yields by destructive distillation so called amber oil, which has a sp. gr. of from 9'i5 to 9*75, consisting mainly of phenols. AMBERGRIS A greyish-brown organic substance found in the intestinal tract of the sperm whale, soluble in alcohol, and greatly valued by perfumers on account of its fine musk- like scent ; sp. gr. 0*908 to 0*920, melting at about 40 C. AMETHYST A native form of silica coloured with iron and other metallic oxides. AMIDES, or acid amides, are amino compounds containing the group or radical NH 2 . For instance, urea or carba- mide (CH^O or NH 2 ,CO,NH 2 ) is the amide of carbonic acid, and is prepared by heating ammonium carbamate to 135 C., thus: O = CO(NH 2 ) 2 (Urea) + H 2 (water). An acid amide is the result of introducing the amido group (NH 2 ) in place of the hydroxyl radical of certain compounds. Acetamide (C 2 H 5 NO or CH 3 ,CO,NH 2 ) is a crystalline deliquescent body derived from acetic acid, which is soluble in water and alcohol and melts at 82 C. Benzamide (C 6 H 5 CO,NH 2 ) is a crystalline substance soluble in water and alcohol, with a melting-point of 130 C. Formamide or Methane-amide (CH 3 NO) may be shown as HCO,NH 2 , being derived from H,CO,HO or CH 2 O 2 (formic acid), and the liquid when heated quickly splits up into carbon monoxide and ammonia. Succinamide is C 4 H 8 O 2 or C 2 H 4 (CO) 2 (NH 2 ) 2 . (See also Amines and Imides.) 28 AMIDOL AMINES AMIDOL (diaminophenol dihydrochloride, (C 6 H 8 N 2 O,2HC1) is used with sodium sulphate as a photographic developing agent. AMIDOPYRIN (dimethylaminoantipyrine) A medicinal agent. AMINES (nitrogen or ammonia bases) Substances containing the group NH 2 as in the primary amines, and distinct from the so-called acid amides. They constitute an important class of chemical bodies, and are intimately connected with the alkaloidal bases or alkaloids. They have a more or less ammoniacal odour, produce white clouds with acid vapour as does ammonia, and combine with hydrochloric and other acids to form salts. Like many of the alkaloids, they yield double platinum chlorides. They are divided or classified into a number of groups, of which the "primary " one includes methylamine and ethylamine, which are pro- duced by heating methyl and ethyl cyanates respectively with potash solution, etc. Methylamine (CH 5 N or CH 3 NH 2 ) is found amongst the products of bone distillation and many decompositions of alkaloidal bodies by barium hydrate. It is strongly basic, very soluble in water, possesses a mixed ammoniacal and fish-like odour, and is chemically allied to another substance known as trimethylamine, found in nature in several plants and well known as a constituent of herring brine. Trimethylamine (CH 3 ) 3 N) can be obtained as a colourless liquefied gas of fishy ammoniacal odour, soluble in water, alcohol, and ether. It can be prepared by the interaction of methyl iodide and ammonia, and is to be met with in commerce in solutions of 10 and 33 per cent, strength respectively. The table below shows the relationship between the primary amines : Name. Formula. Boiling-point. Methylamine CH 3 NH 2 Below o C. Ethylamine C 2 H 6 ,NH 2 187 C. Propylamine C 3 H 7 ,NH 2 497 C. Butylamine C 4 H 9 ,NH 2 69-0 C. Octylamine C 6 H U ,NH 2 1 80-0 C. The secondary and tertiary amines corresponding to the above and their relationships are shown by the following table : A MINES A MYGDALIN AMINES (Continued) 29 Name. Formula. Boiling-point. Dimethylamine Diethylamine Trimethylamine Triethylamine CH 3 ,CH 3 ,NH C 2 H 5 ,C 2 H 5 ,NH CH 3 ,CH 3 ,CH 3 .N ^2^5'^2^5'^2^5'^ 8. _o f 5 ** 57-5 C. 4 C. 96 C. Another distinct class of bodies, yet with some chemical relationship, are now known as aromatic amines or Aryl- amines, and of these aniline is the best-known member, and is regarded as benzene (C 6 H 6 ), in which a hydrogen atom has been replaced by the amino group NH 2 (its formula being C 6 H 5 NH 2 ) ; or otherwise as ammonia NH 3 , in which one of the hydrogen atoms has been replaced by phenyl (C 6 H 6 ). Upon this latter view it is sometimes called phenylamine. (See Amides.) AMINO-ACIDS A class of substances derived from fatty acids by the exchange of an amino group for a hydrogen atom in the hydrocarbon radical. For example, acetic acid (CH 3 .CO 2 H) becomes CH 2 (NH 2 ).CO 2 H (amino-acetic acid). Another name for this compound is glycocoll (see Glycocoll). Amino-acids are the chief hydrolytic product of the proteins, and amongst these tryptophane is of peculiar interest, as a supply of this substance in food has been shown to be necessary by certain experiments made on animals. (See Proteins, Vitamines, and Foods.) AMINO-ACETIC ACID See Glycocoll (glycine). * AMMONAL See Explosives. AMMONIA LIQUOR See Coal. AMMONIA-OLEIN A commercial form of sulphonated castor oil. AMMONIA-SODA PEOCESS See Sodium. AMMONIUM AND ITS COMPOUNDS See Nitrogen Com- pounds. AMORPHOUS Without crystalline form. AMPHIBOLE See Hornblende. AMYGDALIN A glucoside, being a white crystalline sub- stance found in the bitter almond, and which, by the action of an enzyme present in the tissue of the almond named 30 A MYGDA LIN A MYLOPSIN AMYGDALIN (Continued) emulsin (synaptase), is decomposed in the presence of water into a number of products, including glucose (C 6 H 12 6 ). Amygdalin is one of a series of so-called glucosides, all of which yield glucose by similar decomposition. The bitter almond is odourless, but directly it is crushed in water this decomposition takes place, and a characteristic odour is produced indicative of the products which are formed. (See Almond Oil and Glucosides.) AMYLACEOUS See Gums, Starches, and Cellulose. AMYL ACETATE (C 7 H 14 O 2 or CH 3 CO 2 C 5 H U ) An alco- holic solution of this substance forms the essence of pears. It is produced by the slow action of acetic acid upon amyl alcohol, and is made by distilling potassium acetate or lead acetate in admixture with amyl alcohol and strong sul- phuric acid. It is a colourless liquid, of sp. gr. 0*866, nearly insoluble in water, having an ethereal aromatic odour, and is largely used for flavouring purposes and as a solvent of cellulose, etc. AMYL ALCOHOL The pure alcohol has the formula C 5 H 12 O, but the commercial article is, or was, a mixture prepared from fusel oil. It is made in large quantities as a solvent of cellulose for making so-called " dope," for use in con- nection with the manufacture of aeroplanes. It is a clear, colourless liquid, of sp.gr. 0-810, boiling at 130 C., soluble in water, alcohol, and ether ; obtained as a by-product in the production of ordinary alcohol from starch or sugar by fermentation. AMYL BUTYRATE (C 4 H 7 O 2 C5H n ) A colourless liquid of sp. gr. 0-859, and boiling-point about 154 C. ; used as a flavouring principle, and in the making of liqueurs. AMYL NITRITE (CgH^NOa) A yellowish liquid, soluble in alcohol and ether, of sp. gr. 0-880, which boils at 97 to 99 C., and is used as a stimulant inhalant in cases of angina pectoris ; also in perfumery. AMYLOPSIN, otherwise known as pancreatic diastase, is one of the enzymes contained in pancreatin capable of con- verting starch into dextrin and maltose. It acts best in neutral or slightly alkaline media at a temperature of between 30 and 45 C., and is destroyed at 65 C. AMYL SALICYLATE ANHYDROUS 31 AMYL SALICYLATE (C 7 H 5 O 3 : C 5 H n ) A colourless or slightly yellow liquid, of sp. gr. 1*045, an( ^ boiling-point about 270 C. ; soluble in alcohol and ether ; used as a flavouring material. AMYLUM See Starch. ANALOGOUS Having resemblance or relation. ANALYSIS The decomposition of substances into their constituent parts or elements. The term is also employed in respect of the processes by means of which chemists ascertain the constituents of substances. ANASTASE A mineral form of nearly pure titanium oxide (Ti0 2 ). ANDALUSITE A mineral form of crystallized aluminium silicate (Al 2 O 3 ,SiO 2 ), found in Andalusia (Spain) and else- where. ANEMOMETER An instrument or device to measure the direction and force of the wind. ANGELICA (Archangelica officinalis) A plant, parts of which are used for flavouring purposes and in the rectification and compounding of gin. The root contains angelic acid (C 5 H 8 O 2 ), a crystalline, colourless substance, which melts at 45 C., and is sometimes used in medicine. ANGLESITE Native lead sulphate, found in Spain, North America, and Cumberland, probably produced by the oxidation of galena (lead sulphide). ANGOSTURA A bitter principle in the nature of an organic base, obtained from the bark of Angustura (Cusparia febri- fuga, or trifoliata). The bark is stated to contain cusparine (C 20 H 19 N0 2 ), etc. ANHYDRIDES Chemical substances resulting from the abstraction of the elements of water from other substances. For instance, the metallic hydrates or hydroxides, of which potassium hydroxide (KHQ) is illustrative, give the cor- responding oxides or anhydrides by deprivation of water ; thus, 2KHO = K 2 + H 2 0. Again, acetic anhydride (C 4 H 6 O 3 ) is similarly obtained from acetic acid ; thus, 2C 2 H 4 O 2 = C 4 H 6 O 3 + H 2 O. In a sense also cymene (C 10 H 14 ) may be regarded as the anhydride of camphor, as by distillation with phosphoric anhydride it yields cymene, C 10 H 16 O = C 10 H 14 + H 2 O. ANHYDRITE See Calcium. ANHYDROUS Devoid of water as a constituent. 32 ANILINE ANIMAL MATTER ANILINE (amino-benzene or phenylamine, C 6 H 5 ,NH 2 ) is an important base from which a great number of dyes are prepared, and is manufactured by acting on nitrobenzene with iron filings and hydrochloric acid, and subsequently distilling with steam after the addition of lime. The following equation expresses the chemical change that thus takes place : C 6 H 6 N0 2 + 3Fe+6HCl=C 6 H 5 ,NH 2 + 2H 2 + 3FeCl 2 . In a more modern process the reduction of nitrobenzene is effected by passing its vapour, mixed with hydrogen gas, over a catalyst at an appropriate temperature. The aniline oil thus produced is the base or starting- point from which a great number of other " intermediates " for dyes are prepared, including dimethylaniline and diethylaniline, and these yield in turn a great number of so-called basic dyes, such as methyl violet, methylene blue, and malachite green. The physical constants of pure aniline, as recently deter- mined, are as follows : freezing-point, 6-24 C. ; boiling- point, 184-32 to 184-39 C. ; sp. gr.j 1-0268 ; and refractive index at 20 C., 1-5850. Aniline is an oily, colourless liquid of peculiar odour, which darkens on exposure to air, and finally dries up into a resin-like mass. It is soluble i in 31 parts water, in alcohol and ether, and behaves as a base like ammonia, but is weaker, poisonous, and forms a number of combina- tions, including aniline hydrochloride (CgH 5 ,NH 2 ,HCl). By boiling aniline with glacial acetic acid, a substance named " acetanilide " (C 6 H 5 ,NH,CO,CH 3 ) is produced. This is otherwise known under the medicinal name of " antifebrine," and is a beautiful crystalline substance, readily soluble in hot water, alcohol, ether, and chloroform, melting at 115 C. There are several homologues of aniline. (See also Amines.) ANILINE SALT Aniline hydrochloride (C 6 H 5 ,NH 2 ,HC1), which crystallizes in large colourless plates, and can be distilled without change. It melts at 198 C., and is soluble in water, alcohol, and ether, ANIMAL CHARCOAL See Carbon. ANIMAL LIFE See Air. ANIMAL MATTER See Carbon. ANIME RESINANTHRACENE 33 ANIME RESIN (or gum) is of several varieties (East Indian, Zanzibar, West Indian, and South American), and is said to be used for fumigation, also in the making of varnishes. Sp. gr. i -06, and melting-point 240 to 250 C. The West Indian variety is the produce of a tree known as the Hymencza, Courbaril. (See Copal.) ANIONS. See Electricity. ANISEED OIL contains a substance called anethol (C 10 H 12 O), is used in flavouring certain liqueurs, and is made from the seed of Pimpinella anisum and the China or star anise (Illicmm anisatum) by distillation with water. It is a thick yellowish, syrupy liquid of sp. gr. 0-975 to 0*990, and re- fractive index 1-54 to 1-56, of peculiar aromatic smell and taste. The yield of oil from the seeds is about 2-4 per cent. Anethol is also obtained from fennel (Anethum fcenicidum) and tarragon (Artemisia dracimcukis). ANNATTO A colouring matter made from the seeds of the Bixa orellano, cultivated in Guiana, St. Domingo, and the Indies. It dissolves in alcohol with an orange-red colour, and is said to contain a crystalline yellow substance named bixin, which in the presence of alkalies absorbs oxygen and turns red. It is a fugitive colour, used in dyeing and for colouring cheese, etc. ANORTHITE A mineral compound silicate of aluminium and calcium. ANTHOCYANINS See Plant Colouring Matters. ANTHRACENE (C 14 H 10 or CgH 4 .CH.CH.C 6 H 4 )--A product of the destructive distillation of coal, present in coal-tar to the extent of from J to nearly per cent. In the pure state it is a yellow crystalline body, and exhibits a fine blue fluorescence. It is obtained from the so-called anthracene oil, which distils over between 270 and 400 C., and forms about 12 to 17 per cent, of the tar. Upon cooling, the crystals of anthracene are separated from the oily mother- liquor by pressing and centrifugalizing. This crude pro- duct, containing about 40 per cent, anthracene, is further purified from naphthalene, phenanthrene, crysene, carba- zole, and other bodies with which it is associated, by exposure to steam when placed in a hydraulic press, after which it is washed with a mixture of solvent naphtha mixed with pyridine bases. In this way a product con- taining about 90 per cent, anthracene can be obtained. The chemically pure anthracene is obtained by grinding up the crude substance with caustic potash and lime, and 3 34 A NTHRA CENEA NT I MO NY ANTHRACENE (Continued) redistillation, the product being finally washed with solvent, and sublimed. Anthracene melts at 216 C., boils at 351 C., and is used for making various aniline colours, especially Turkey red. (See Alizarin.) ANTHRACITE A hard coal, which burns with little smoke and flame, and contains from 85 to 95 per cent, carbon. ANTHRAQUINONE (C 14 H 8 O 2 or C 6 H 4 (CO) 2 C 6 H 4 ) A product of the oxidation of anthracene. It crystallizes in yellow needles, melts at 285 C., and is soluble in alcohol, ether, and acetone. ANTICHLOR A term used by bleachers in respect of chemicals, such as sodium sulphite and sodium thiosulphate, employed for the purpose of obviating any deleterious after- effects of the action of chlorine preparations used in bleach- ing operations by removing the residual chlorine. ANTIFEBRINE See Acetanilide. ANTIMONY (Stibium, Sb) and its compounds Atomic weight, 120 ; sp. gr., 67 ; melting-point, 630 C. Antimony is found naturally in small quantities, but in greater quantities it exists combined with oxygen as so-called white antimony (Sb 2 O 3 ), and in another form as antimony ochre (Sb 2 O 4 ). Its chief ore is the trisulphide stibnite (Sb 2 S 3 ), or grey antimony ore, whilst other combinations with oxygen and sulphur are antimony blende (Sb 2 O 3 ,2Sb 2 S 3 ), and red antimony (kermisite). Antimony mining is conducted on a considerable scale in Bolivia, China, Mexico, the United States of America, and elsewhere. Antimony is a bright bluish-white crystalline metal, largely used in making alloys. Type metal consists of lead 75 parts, antimony 20 parts, and tin 5 parts. Stereotype metal consists of lead 112, antimony 18, tin 3 parts; and Britannia metal, tin 140, copper 3, antimony 9, all of which give fine and sharp castings. Antimony is also used for producing the appearance of polished steel on papier-mache ; the tetroxide is used for rendering enamels opaque, and the trioxide for colouring glass, and as a paint. The red sulphide is used for vulcan- izing rubber and for preparing the striking surface on safety-match boxes. (See Phosphorus.) Alloyed with lead, it has been largely used in the great war in preparing shrapnel bullets, and the sulphide in making shell primers and as a smoke producer. The metal is prepared by heating the broken-up native ANTIMONY ANTIPYRINE 35 ANTIMONY (Continued) trisulphide with half its weight of scrap iron in plumbago crucibles, when iron sulphide is formed, and the metallic antimony set free, as follows : Sb 2 S 3 + 3Fe = 2Sb + 3FeS or the selected sulphide separated from the associated rocky matter of the ore can be mixed with charcoal or coal and heated in a reverberatory furnace ; the sulphur in this way is burnt off as sulphur dioxide. Antimony is a bad conductor of heat and electricity and is not acted upon by the air. When strongly heated, it burns in air or oxygen with a brilliant light and forms antimony trioxide (Sb 2 O 3 ). When thrown into chlorine gas it takes fire and forms antimony trichloride (SbCl 3 ). There are two chlorides of antimony viz., the tri- chloride (SbCl 3 ), which is used as a mordant and for bronzing iron, etc., and the pentachloride (SbClg) ; and three oxides viz., the trioxide (Sb 2 O 3 ), the tetroxide (Sb 2 O 4 ), and the pentoxide (Sb 2 O 6 ). The trichloride (butter of antimony) is a colourless crys- talline body, soluble in water and alcohol, and is used in bronzing iron, as a mordant for making lakes, and colouring zinc black. When the trioxide is dissolved in a boiling solution of potassium hydrogen tartrate (cream of tartar), potassium antimony tartrate or tartar emetic is formed. This compound is used medicinally. Two sulphides are known viz., the trisulphide (Sb 2 S 3 ), which is used as a pigment, and the pentasulphide (Sb 2 S 5 ). The trisulphide occurs in nature as the black crystalline stibnite, but when precipitated from solutions it is an orange- red compound. Antimony hydride or antimoniuretted hydrogen (SbH 3 ) is produced when an antimonial solution is brought into contact with zinc and sulphuric acid. It is a colourless gas of offensive odour, which can be obtained also in liquid and solid forms. Antimony lactate (Sb(C 3 H 5 O 3 ) 3 ) is soluble in water, and is used as a mordant. Antimony forms compounds with the alkyls similar to those of arsenic, for example, trimethyl-stibine, Sb(CH 3 ) 3 , a disagreeable inflammable liquid. ANTIPYRINE (Phenazone) (C U H 12 N 2 or C 6 H 5 (CH 3 ) 2 C 3 HN 2 0) A white crystalline substance which melts at 113 C, is 36 ANTIPYRINEARACHIS OIL ANTIPYRINE (Continued) soluble in water, alcohol, and ether, and constitutes an excellent febrifuge and an alleviative to neuralgic pains. ANTISEPTICS Preventives of septic poisoning or decom- position in the nature of putrefaction. APATITE A mineral compound of phosphate and fluoride of calcium^(3Ca 3 (PO 4 ) 2 ,CaF 2 ), occurring in the United Srates and Canada, etc. APIOL An oil obtained from the fruit of parsley, pale green in colour, sometimes used as a diuretic. APPARATUS The utensils and appliances used by chemists. AQUADAG See Lubricants. AQUA FORTIS An old name for nitric acid. AQUA REGIA A mixture of nitric and hydrochloric acids a very powerful solvent. Gold and platinum, for example, can be dissolved by this mixture, which is commonly made of 1 8 parts and 82 parts of the respective acids. AQUEOUS VAPOUR (Atmospheric) The water or moisture held dissolved in vaporous solution in the air. (See Air.) ARABINOSE (C 5 H 10 O 5 ) A white crystalline body soluble in water, is a constituent of many plants, and can be made by boiling gum arabic or cherry gum with dilute sulphuric acid. ARACHIDIC (ARACHIC) ACID (C 20 H 40 O 2 ) A member of the normal fatty acids, found in the oil of the earth-nut (Arachis hypogcea). It is a crystalline body which melts at 75 C., and is soluble in boiling alcohol and in ether. (See Arachis Oil.) ARACHIS OIL (Earth-nut Oil, Pea-nut Oil) A fatty oil, of which there are many grades, expressed from the fruit of Arachis hypogcea, a leguminous plant indigenous in India, South Africa, and South America. It is pale yellow, of agreeable odour, of non-drying character; is soluble in alcohol, ether, benzol, and carbon disulphide, has a sp. gr. of 0-916 to 0-925, a saponification value 185 to 196, and iodine value 92 to 101. It is used as a salad oil and substitute for olive oil, for soap-making, and as a delicate lubricant by watchmakers. Chemically, it is a glyceride of ararchidic acid. A recent examination of the fatty acids obtained from a sample with an iodine value of 86 -i showed the presence of 2 -3 arachidic acid, 1-9 lignoceric acid, 4*5 stearic acid, 4-0 palmitic acid, 79-9 oleic acid, and 7*4 linoleic acid. ARCHIL ARRACK 37 ARCHIL A purple dye obtained from many kinds of lichens, including the geni Rocella and Variolaria orcina, etc., a number of which contain certain colourless acids which are capable of transformation into a colourless substance termed orcin, which, by the action of air and ammonia, is changed into the purple body called orcein (C 28 H 24 N 2 O 7 ) the colouring principle of archil. The Rocella pemviana occurs in abund- ance around Magdalena Bay (Lower California), as much as 100,000 tons being harvested in 1917. The lichen is torn from the trees, and, after drying, is ground to a coarse powder, and then macerated during several weeks in dilute ammonia with frequent stirring. It is expensive and perishable, and is used as a dye for cloth and silk Marble, however, stained with it retains the colour well. Cudbear is a variety of archil, and the bright blue it gives to silks is said to be much more permanent. ARECA (Betel) A genus of plants, including the Areca catechu, the ground-nut of which contains numerous alka- loids and is used as a vermifuge, especially for dogs. ARGENTITE (" Silver glance ") A native form of silver sulphide (Ag 2 S) occurring in cubic crystals, containing 87 per cent, silver, found in several of the United States of America. ARGILLACEOUS Clayey in character. ARGOL Crude tartar as deposited in wine casks or at the bottoms of fermenting vessels. (See Tartar.) ARGON (A) Atomic weight, 39*88. Argon is a recently dis- covered element found present in the gaseous state in the air to the extent of rather less than i per cent, by volume, and also in minute quantity in Bath and other mineral spring waters. It is isolated by processes which remove the oxygen and nitrogen respectively. It is a remarkably inert substance, and has been liquefied and frozen to a white solid. No chemical combinations of it are known. The density of the gas is 19*94, an( ^ ** * s soluble in water to the extent of 4*1 volumes in 100 at 15 C. It boils at 187 below o C. According to Ramsay, the fractional distillation of argon yields traces of other gases having distinct spectra, and to these he gave the names of Neon, Xenon, and Krypton. ARRACK A spirituous drink prepared by the fermentation of an infusion of rice. A similar preparation known as " palm wine " is made in Ceylon from cocoa-nut toddy. 38 A RRA GONITEA RSENIC ARRAGONITE-See Calcium. ARROWROOT See Starch. ARSENIC (As) and its compounds Atomic weight, 75; sp. gr., 5-62; melting-point, 850 C. (under pressure). Arsenic occurs in nature in the metallic state and in com- bination with sulphur as realgar (As 2 S 2 ) and orpiment (As 2 S 3 ). It is also found in other combinations with iron (arseno- pyvite or arsenical iron, FeAs 2 and Fe 4 As 3 ), and mispickel (FeS 2 + FeAs 2 ), with nickel (kupfernickel, NiAs and NiAs 2 ), and with cobalt. Arsenopyrite occurs abundantly in Ontario, and there are orpiment mines in Chitral, while some arsenic is produced in Queensland, Western Australia, United States, France, and Cornwall, but it is chiefly produced from the silver-cobalt-nickel-arsenic ores of the Ontario cobalt district as a by-product. It is of grey colour, sublimes at 450 C., and is used for mixing in small proportion with lead when melted to make shots, which are harder than those made with pure lead. It has a vapour density of 150. The metal is manufactured from arsenical pyrites by roasting it in vessels fitted with suitable condensers for receiving the arsenic which is liberated and volatilized by the splitting up that occurs, ferrous sulphide being left behind FeS 2 ,FeAs 2 = 2FeS + 2 As. In its ordinary form it is crystalline and is a good con- ductor of heat and electricity, but an amorphous form is also known. Arsenic Hydride (AsH 3 ), otherwise known as arsine and " arseniuretted hydrogen," is an offensive smelling colour- less poisonous gas which can be prepared by the action of dilute hydrochloric or sulphuric acid upon an alloy of arsenic and zinc. It burns with a bluish flame, forming water and arsenious oxide, but if the amount of air is limited, metallic arsenic is deposited. The so-called Marsh's test is based on this change. Arsenious Oxide (As 2 O 3 ) is manufactured as a secondary product in the roasting of many arsenical ores for the recovery of the associated metals nickel, cobalt, silver, and tin large quantities being pro- duced in the United States of America, chiefly at Bute (Mass.),Tintic (Utah), and Tacona( Wash.), being recovered from the smelter fume. It is commonly known as "white arsenic," and is used not only in the manufacture of certain ARSENIC A SBESTOS 39 ARSENIC (Continued) pigments and flint glass, but largely for the preparation of sodium arsenite (Na 3 AsO 3 ), which is made by dissolving the oxide in caustic soda or sodium carbonate solution, and used as a weed - killer and horticultural insecticide. Arsenious oxide is very poisonous, and so also are most of the arsenical compounds. The world's production of white arsenic has been estimated as between 20,000 and 25,000 tons. Arsenic Pentoxide (As 2 O 5 ) is obtained by oxidizing arsen- ious oxide with nitric acid. Arsenic Bisulphide (As 2 S 2 ) is an orange-red powder in- soluble in water (prepared by roasting mispickel and iron pyrites and sublimation), used in a number of industries, including calico-printing, the manufacture of leather, shots, and paints, and as a depilatory agent. It is also found native as Realgar. The trisulphide (As 2 S 3 ) (found native as Orpiment) and the pentasulphide (As 2 S 5 ) are yellow substances insoluble in water, and are both used as pigments in paint-making. Arsenic resembles phosphorus and nitrogen in the sense that it forms analogous compounds with alkyl radicles, as, for example, tri- methyl arsine, which is analogous to tri- methlyamine and tri-methyl phosphine. (See Cacodyl.) ARSINE See Arsenic Hydride, p. 38. ARTIFICIAL SILK See Cellulose and Silk (artificial). ARUM See Starch. ASAFCETIDA A resinous gum from the root of the Ferula asafcetida, an umbelliferous plant which grows in Thibet, Persia, and Turkestan. It has a strong offensive odour, is much more soluble in alcohol than in water, and upon dis- tillation with water, yields about 3 per cent, of a sulphuretted volatile oil (of sp. gr. 0-975 to '99)> to which its odour is due. It is a powerful antispasmodic, and is used in hysterical cases and in cases of flatulent distension of the bowels. ASBESTOS A fibrous variety of the mineral amphibole, being a compound silicate and aluminate of magnesium, calcium and iron. The name, however, is applied not only to the minerals tremolite, actinolite, and other varieties of amphibole, but to fibrous forms of pyroxene, the different mineral crocidolite (distinguished by its large proportion of ferrous iron constituent) and to chrysotile y a fibrous variety of ser- 40 ASBESTOSASHES ASBESTOS (Continued) pentine which differs in that it is a hydrated silicate, whereas all the others are anhydrous. Most of the commercial supplies come from the Province of Quebec, but asbestos occurs also in China, Italy, and many of the United States of America, while chrysotile deposits are found in Russia, and South Africa yields supplies not only in that form, but also as crocidolite and amosite. Asbestos is manufactured not only into cloth and fabrics for fireproof clothing and theatre curtains, but also into yarn, packing, boiler coverings, and many other useful forms and is employed in compounding a number of build- ing and roofing materials. It withstands heating to a high temperature, and, as it is not acted upon by many chemicals, is often employed in laboratories ; for example, in the form of fibres for plugging the ends of glass tubes in order to retain their chemical contents within prescribed limits. In the form of woven mats or cloths it is useful as a soft, non- conducting material on which may be stood flasks or beakers containing hot solutions. It is also employed as a covering for the central part of wire gauze used on the top of iron tripod stands, thus preventing oxidation by rusting, affording a softer seat for glass vessels placed thereon when required to be heated by lamps below, and for the better distribution of the flame. In the fibrous form it also finds employment as a filtering material wherewith to plug the neck of funnels for separating solid and liquid materials, particularly when it is known that a paper filter would become easily clogged or destroyed by the chemical mixture ; and although the filtrate may not be quite clear, it then admits of more rapid and perfect filtration through an ordinary paper filter. "ASEPTOL" A trade name for an antiseptic solution of phenol sulphonic acid (C 6 H 4 (OH)SO 3 H). ASHES All woods, weeds and vegetable growths, as well as coal, peat and lignite, leave ashes when burned and all ot them contain some amount of alkali. Potash was originally produced from the ashes of plants and a process is now in use for its recovery from the coal used in blast furnaces. As K 2 O it amounts to from about 10 per cent, in the ashes of straw to 42 per cent, in that from peas. The potash is associated with varying amounts of soda, lime, magnesia, iron oxide, sulphur in the form of sulphates, silica, carbon dioxide, and phosphoric acid. ASHES ASPIRATOR 41 ASHES (Continued) The woods which yield the greatest amount of potash are wormwood and fumitory. ASPARAGINE (C 4 H 8 N 2 O 3 ) An amidated body contained in asparagus, potatoes, beet-roots, vetches, and the juices of other vegetables including the marsh mallow, liquorice juice, the tubers of the dahlia, and the shoots and young leaves of many leguminous plants. It forms small hard inodorous crystals, soluble in 1 1 parts cold and 5 parts hot water, and when heated with strong acids or alkalies, is resolved into aspartic acid and ammonia. It forms certain definite compounds with acids. ASPARTIC ACID or AMINO-SUCCINIC ACID (C 4 H 7 NO 4 ) A crystalline body contained in beet-root molasses, and found among the products of the decomposition of proteids by hydrolysis. It also results from the hydrolysis of aspara- gine the acid amide contained in asparagus and some other vegetables. ASPHALT Natural solid or semi-solid bitumen, black or brownish- black, deposits of which are found in many places, including Alabama, Trinidad, San Valentino, Chieti in Italy, Java, Cuba, Seyssel (on the Rhone), Texas, Utah, Val de Travers (near Neuchatel), Venezuela, and Limmer (near Hanover). It is supposed to have been formed from the high-boiling mineral oils by oxidation, melts at from 32 to 100 C., is combustible and largely soluble in naphtha and turpentine. It is used for lining water-tanks, in the construction of asphalt pavings and cements, and as a component of some varnishes. The bituminous constituents of asphalt, which are insoluble in petroleum, closely resemble coal in characters, and are termed asphaitenes. ASPIRATOR An arrangement for aspirating or drawing a current of air or other gas through a vessel or through a liquid contained in one. When only a small volume of air is wanted, a fitted-up Winchester bottle (as shown in the figure) may be used. A represents a flask containing the liquid through which it is desired to draw the current of, say, air ; B rubber tubing connecting glass tube from A to glass tube going just through the cork of the Winchester, C ; D glass tube going to bottom of C and joining up at E with a length of rubber tubing dropping down into the sink of the laboratory, but fitted at F with a pinch -cock for regulating the flow of water from C into the sink. The flow is first of all started by sucking at the end of this 42 A SPIRA TOR A TOMS ASPIRATOR (Continued) rubber tubing and thus drawing the water from C, the flow being subsequently regulated by closing or relaxing the pinch-cock (F). In this manner D really acts as a siphon- tube. (See Siphon.) ASPIRIN or ACETOSAL (Acetyl Salicylic Acid) (C 9 H 8 O 4 ) A white crystalline powder, being an acetic derivative of salicylic acid which exists in meadowsweet, and is also manufactured for use as an intestinal antiseptic and for other medicinal applications. It melts at from 132 to 135 C., and is soluble in alcohol and ether, but only slightly soluble in water. ASSAYING The art of chemically estimating or determining the several amounts of metals contained in minerals, ores, alloys, and metallurgical products. ASTRINGENT Bitter, harsh taste. ATACAMITE A native oxychloride of copper found in the form of light green rhombic crystals in the desert of Atacama in Peru and elsewhere. ATMOSPHERE See Air. ATOMS are generally described as the smallest parts of any chemical elements that can exist in a state of combination or take part in a chemical change. They are supposed to be indivisible, although conceivably everything, no matter how small, can be again divided into two parts. In the past it was supposed that all the atoms of any one element are of the same size and weight, and that they differ from those of all the other elements in mass (weight) and ATOMS ATOMIC WEIGHTS 43 ATOMS (Continued) chemical properties. Hydrogen is the lightest in weight, and platinum is one of the heaviest. Oxygen is sixteen times heavier than hydrogen, and these relative weights are termed their atomic weights. There is a rapidly developing tendency to regard all matter as composed of a unit element in view of the results of recent researches in physics respecting atomic structure, experiments con- cerning radio-activity having demonstrated the transference of the apparently distinct substances or chemical entities into others. Accordingly, it is conjectured that atoms consist of positively charged nuclei surrounded at a distance by distributed electrons or charges of electricity, the normal (atomic) number being equal to the number of unit positive charges in the nucleus which makes them electrically neutral. The nuclei are supposed to contain the mass of the atoms although of exceedingly small dimensions, the diameter being of the order of o-ooooi of that of the atom, and the region occupied by the external electrons very large in comparison. Viewed thus, the nuclear charge of the hydrogen atom is one unit of electricity, that of helium two charges, and so forth up to uranium (the heaviest atom) with a charge of 92 units. It is obvious that subject to this hypothesis, electricity is endowed with the properties of matter, and the so-called elements therefore as systems of electricity, differing in the number of electrons and in their motion relative to each other. Further, it is supposed that if the number of electrons in the atom exceeds the atomic number, it is a negatively charged atom or ion, while, reversely, the atom is positively charged. From a recent study of the deflection of particles liberated from atmospheric nitrogen under certain conditions, it has been concluded that hydrogen is one of the products of the disintegration of the nitrogen atom. The problem of the essential constitution of atomic matter must, however, be regarded as at present pro- blematical. (See Elements, Matter, and Radio-activity.) ATOMIC VOLUME The atomic volume of an element is the atomic weight divided by its specific gravity. ATOMIC WEIGHTS The atomic weights ordinarily adopted are those expressed in relation to hydrogen as the unit, but in the following table they are also given in relation to oxygen, taken as the standard of comparison (16), the atomic weight of hydrogen then becoming roo8. These international weights are revised yearly in the light of the 44 INTERNATIONAL ATOMIC WEIGHTS ATOMIC WEIGHTS, 1921. *i Jj "I * II K ! II 1* 2 12 f| M 3 |i II U y >, o O V >, C y Is CO Si C o ' CO c'l 1* ~< IJ, "" <5 w X Aluminium 27 Al 27-1 Neon 20 Ne 2O 2 Antimony ... 120 Sb 1 2O '2 Nickel 59 Ni 58-68 Argon 40 A 39 '9 Niton (radium Arsenic 75 As 74-96 emanation) Nt 222'4 Barium 137 Ba 137*37 Nitrogen 14 N 14-008 Bismuth 208 Bi 208*0 Osmium 191 Os I90-9 Boron ii B 10-9 Oxygen 16 16-0 Bromine 80 Br 79-92 Palladium ... 106 Pd 106-7 Cadmium ... 112 Cd 112-4 Phosphorus 3i P 31-04 Caesium 133 Cs 132-81 Platinum ... *95 Pt 195-2 Calcium 40 Ca 40-07 Potassium ... 39 K 39*i Carbon 12 C 12-005 Praseody- Cerium 140 Ce 140-25 mium I 40'5 Pr 140-9 Chlorine 35'5 Cl 35-46 Radium 226-4 Ra 226-0 Chromium ... 5 2 Cr 52-0 Rhodium ... 103 Rh 102-9 Cobalt 59 Co 58-97 Rubidium ... 85 Rb 85-45 Columbium 93-i Cb 93'i Ruthenium ioi'7 Ru 101-7 Copper 63-5 Cu 63'57 Samarium ... 150 Sa 150-4 Dysprosium Dy 162-5 Scandium ... 44 Sc 45*i Erbium 1 66 Er 167-7 Selenium ... 79 Se 79*2 Europium ... Eu 152-0 Silicon 28 Si 28-3 Fluorine 19 F 19-0 Silver 108 Ag 107-88 Gadolinium Gd i57'3 Sodium 23 Na 23-0 Gallium 70 Ga 70-1 Strontium ... 87-6 Sr 87-63 Germanium 72 Ge 72-5 Sulphur 32 S 32-06 Glucinum ... Gl 9-1 Tantalum ... 181 Ta 181-5 Gold 197 Au 197-2 Tellurium ... 127 Te 127-5 Helium 4 He 4-0 Terbium Tb 159-2 Holmium ... Ho 163-5 Thallium ... 204 Tl 204*0 Hydrogen ... i H i -008 Thorium 232 Th 232-15 Indium "5 In 114-8 Thulium ... Tm 168-5 Iodine 127 I 126-92 Tin 118 Sn 118-7 Iridium 193 Ir 193-1 Titanium ... 48 Ti 48-1 Iron... 56 Fe 55-84 Tungsten ... 184 W 184-0 Krypton 83 Kr 82-92 Uranium ... 238-5 u 238-2 Lanthanum 139 La 139-0 Vanadium ... 5i V 51-0 Lead 207 Pb 207-2 Xenon 130 Xe 130-2 Lithium 7 Li 6-94 Ytterbium Lutecium ... Lu 175-0 (Neo ytter- Magnesium 24 Mg 24-32 bium) 172 Yb i73'5 Manganese 55 Mn 54*93 Yttrium 89 Yt 88-33 Mercury 200 Hg 200-6 Zinc ... 65 Zn 6537 Molybdenum 96 Mo 96-0 Zirconium ... 907 Zr 90-6 Neodymium 144 Nd J 44*3 ATOMIC WEIGHTS A URINE 45 ATOMIC WEIGHTS (Continued) most recent investigations. The atomic weights may be connected by precise mathematical equations, but if so the nature of these relationships have not yet been discovered. (See Table on p. 44.) ATROPINE (C 17 H 23 NO 3 ) is a highly poisonous organic base or alkaloid, isomeric with hyoscyamine, prepared from Atropa belladonna (*' deadly nightshade "), both of which are remarkable for their power of dilating the pupil of the eye. It crystallizes in colourless prisms or needles, which melt at 114 to 115 C., and is soluble in water, alcohol, and ether. Belladonna leaves should contain a total quantity of about 0*4 per cent, alkaloids. Preparations of bella- donna are used in medicine in the form of tinctures, extracts, and plasters to check excessive secretion and to allay inflammation. (See Belladonna Oil.) ATTAR OF ROSES (otto of roses) is obtained by distilling the fresh flowers of Rosa damascena with water, and is made in Bulgaria, France, Turkey, Persia, and India, 3 drachms being obtained from 100 pounds of the flower-petals. The distilled oil is pale yellow, and has a sp. gr. of 0*853 * 0*862. Its refractive index is 1*460 to 1*465, and rotation - 2 to - 4. It contains from 70 to 75 per cent, of its odourous constituents namely, geraniol and citronellal. It also contains an odourless substance (stearoptene) to the extent of from 10 to 16 per cent., consisting of a mixture of two hydrocarbons insoluble in alcohol, and which can be frozen out by cooling the oil below 18 C. The odoriferous constituents of the oil are soluble in alcohol. Otto of roses is frequently adulterated with geranium oil. It is chiefly used in perfumery and for flavouring. ATTENUATION A term used by bacteriologists to signify the weakening of bacterial life, and by brewers to signify the weakening of worts by fermentation of the contained sugars. The same term is used by chemists to signify the rarefication or thinning of gaseous bodies. (See Vacuum.) ATTRACTION See Chemical Attraction. AUBEPINE anisic aldehyde (C 8 H 8 O 2 ) A colourless liquid of aromatic odour, soluble in alcohol and ether, and used in perfumery. AURIFEROUS A term applied to ores or minerals containing gold. AURINE (C 19 H 14 O 3 ) A dye which crystallizes in beautiful green needles and prisms of a metallic lustre, and can be 46 A URINE B A CTERIA AURINE (Continued) made by heating phenol with a mixture of sulphuric and oxalic acids to a temperature of from 130 to 150 C. Its constitution is shown by the structural formula : C e H 4 OH AUTOCLAVES Apparatus for maintaining liquids at any desired temperatures and pressures in chemical labora- tories, and constituting an important part of the plant used in chemical industry. AVOGADRO'S LAW See Molecules. AZO-DYES A large class of dyes containing one or more so-called azo groups - N : N linking together aromatic radicles. Many of them dye cotton without the use of a mordant, whilst others act as very fast mordant dyes on wool. They may be regarded as originating from the red crystalline parent substance, azobenzene, C 6 H 5 : N :N.C 6 H 5 , all its basic and acid derivatives being colouring matters. Azobenzene itself is obtained from nitrobenzene by reduction of a solution of that substance in ether containing water by means of sodium amalgam. These groups of atoms, such as N:N or - N = N , are known as chromophors, and produce dyes when intro- duced into so-called chvomogens or compounds which contain unsaturated groups of C 6 arranged as in benzene. AZURITE A blue basic copper carbonate (2CuCO 3 ,Cu(HO) 2 ) found in the native state at Chessy, near Lyons, the United States of America, and elsewhere ; also known as chessylite. (See Copper.) BACTERIA are microscopic organisms of which the largest is less than -^ of an inch in length, while some of them require to be magnified thousands of times to become visible. They abound universally and constitute the simplest and lowest known forms of life. They, or some of them, are the indirect causes of certain infectious diseases, and they are capable of inciting many chemical changes in the nature of fermentations, oxidation, and hydrolysis. The souring of milk is caused by the Bacterium lactis, that of dilute wine by the Mycoderma aceti, etc. Most bacteria are destroyed when heated for a short time to the temperature of boiling water (100 C.), particularly in the presence of moisture, and all of them after a prolonged exposure. They are also readily destroyed by a number of BACTERIA BALSAMS 47 BACTERIA (Continued) chemical agents, including a solution of corrosive sublimate (i in 1,000), exposure to formaldehyde in liquid or vaporous form of sufficient strength, or to the vapour of sulphur dioxide as generated by burning sulphur candles (particu- larly when in association with water vapour), and by many disinfectant preparations. Many kinds develop by spore-bearing, and the spores are usually more difficult to kill than the fully developed germs. The activities of bacteria are not confined to organic compounds, many changes affecting the earth's surface being due in part to biological influences in which these micro-organisms participate. Various iron compounds, for example, came within their influence, ferric hydroxide being precipitated from solutions of ferrous bicarbonate by the action of a group of bacteria, and they are regarded as factors in the natural production of many deposits of ferruginous sedimentary ores. Sulphuretted hydrogen results as a product of decomposition of animal and vege- table matters by saprophytic bacteria, and this, by action on iron compounds, is supposed to be connected with the formation of the " blue mud " of the ocean bottoms. (See also Nitrification.) " BACTEROL " A proprietary antiseptic containing formalde- hyde associated with small proportions of other substances. " BACTOX " A powerful proprietary antiseptic and dis- infectant made from certain phenoloids in a form miscible with water. " BAKELITE " The trade name of a black material made from phenol by the action of formaldehyde, used as a plastic, and for insulating purposes. BAKING-POWDERS Preparations used as substitutes for yeast in making bread spongy in character by the pro- duction of carbon dioxide in the dough. The joint use of tartaric acid and sodium bicarbonate will produce such a result for example. BALATA The rubber gum, or coagulated latex of Mimusops globosa a forest tree of the order Sapotacece, which grows in Guiana and elsewhere, known otherwise as the " bully tree." It resembles gutta-percha in nature and properties, and finds many similar commercial applications. BALSAMS are natural products consisting of essential or volatile oils admixed with resins which are supposed to be derived from the oils by atmospheric oxidation. 48 BALSAMS BALSAMS (Continued) Copaiba Balsam is produced by several varieties of Copaifera indigenous in Brazil, Peru, Mexico, and the Antilles. It flows from incisions made for that purpose in the trees during rainy weather, and in this form it is a syrupy, oily liquid varying in character and properties according to the species of trees from which it is obtained. By exposure to the air it becomes solid and is used not only in medicine but also in preparing lac varnishes and tracing paper. It is soluble in alcohol, ether, chloroform, benzol, and carbon disulphide, and has a sp. gr. 0*940 to 0*990. Mecca Balsam or Balm of Gilead is the produce of the Balsamodendron gileadense, a terebinthaceous shrub, native of Arabia Felix. There are several varieties and the finest quality of fragrant odour is said to exude from the flowers, whilst an inferior quality is obtained from incisions in the branches. It is not much used in medicine now, but in the East it is used as a tonic. Peru Balsams are of three varieties (white, dry and black), sp. gr. 1*14 to 1*15 ; soluble in alcohol and ether. Storax ^Balsam (Oriental sweet gum) is the produce of Sty rax officinalis (a shrub growing in the Levant, Palestine, Syria and Greece). This is known in two varieties viz., liquid and solid forms, soluble in ether and hot alcohol, and is used in medicine as a stimulating expectorant, in perfumery, and as a detergent in the form of ointment. The semi-liquid balsam from Liquidambav orientate, known in the U.S.A. as "sweet gum," contains over 28 per cent. cinnamic acid (C 9 H 8 O 2 ), a substance which, when fused with potash, splits up into benzoic and acetic acids. The American storax is derived from Liquidambar styraxi- flora, found in great forests high up in the mountains of Honduras. Tolu Balsam, a nearly solid, resinous mass of aromatic odour used in medicine ; is obtained in large quantities from Myrospermum toluiferum, growing in various parts of Columbia and South America. It contains benzoic and cinnamic acids. Canada Balsam or Canadian Turpentine is produced by Abies balsamea, a conifer which grows in Canada, Virginia, Carolina, and, like all the turpentines, is produced by making incisions in the stem. So also in common with other crude turpentines, when distilled it yields turpentine oil and leaves resin behind in the retorts, It is a yellowish BALSAMS BARIUM 49 BALSAMS (Continued) viscid liquid, of pleasant, pure odour and bitter taste, soluble in ether, chloroform-, benzol, etc. (See Gums and Essential Oils.) BAEBARY GUM The product of the African Acacia gummif era. BAEBEY IXOMETEE An apparatus for determining the fluidity of oils by the rate of flow. It is so constructed that a pressure of 100 millimetres of liquid is kept at a fixed temperature of 35 C. Raw colza oil freshly prepared and drawn off marks exactly 100 of fluidity by this apparatus. BAEBITONE (C 2 H 5 ) 2 .C(CONH) 2 CO) Another name for veronal (diethylbafbituric acid), a white crystalline body, soluble in water, which is used as a soporific; melting- point 182 C. BAEIUM (Ba) and its compounds Barium is a yellow, lustrous metal of malleable character, having an atomic weight, 137 ; sp. gr., 3-78 ; and melting-point, 850 C. Barium sulphate (BaSO 4 ) is abundantly found in nature in the forms of heavy spar or barytes (in the metalliferous mines of Durham, Cumberland, and Westmorland, and in the secondary limestone in many places), and barium car- bonate (BaCO 3 ) occurs as witherite. The home output of barium minerals in 1918 amounted to 66,360 tons. Barium Chloride (BaCl 2 2H 2 O), a colourless, crystalline salt, is obtained by dissolving the native carbonate in hydrochloric acid and crystallizing it out of solution when it forms rhombic tables, which are very soluble in water. It is used in the leather industry, as a rat poison, and in making boiler compounds. When barium chloride in solution is mixed with a dilute solution of sulphuric acid (H 2 SO 4 ), barium sulphate is precipitated in an insoluble form BaCl 2 + H 2 S0 4 = BaS0 4 + 2HC1. Barytes, in the forms of finely ground heavy spar, as also the precipitated sulphate, are both used in compounding several distinct pigments, including permanent white and blanc fixe, and for admixture with white lead in paint-making. Barium Nitrate (Ba(NO 3 ) 2 ) is obtained by dissolving witherite in dilute nitric acid. It crystallizes in large colourless octahedra and is soluble in water, but not so soluble as the chloride, and is used in pyrotechnics for making green fire. 4 50 BARIUM BARIUM (Continued] Barium Sulphide (BaS), a yellowish-green substance, soluble in water, is sometimes used as a luminous paint, as it possesses, in common with calcium sulphide (CaS), the property of emitting a feeble phosphorescent light in the dark. It is also used as a depilatory, in vulcanizing, and for weighting gutta-percha. It is prepared from barium compounds by methods similar to those used in the pre- paration of the corresponding calcium sulphide. There are two oxides of barium white insoluble bodies viz., the monoxide (BaO) and dioxide (BaO 2 ), the last- named of which is used in the manufacture of hydrogen dioxide. When the monoxide is slaked with water it gives rise to the formation of a hydrate or hydroxide (BaH 2 O 2 ) which is fairly soluble in hot water and can be obtained in a crystalline form. Barium Acetate (Ba(C 2 H 3 O 2 ) 2 H 2 O) A white crystalline salt, soluble in water. Barium Carbonate (BaCO 3 ) A white compound, in- soluble in water, used in ceramics, and in the form of a paste, regarded as one of the most effective poisons for rats. A mixture, largely used in India, is prepared from : Barium carbonate ... ... 6 ounces. Common salt ... ... ... \ ounce. Wheat flour ... ... ... 4 ounces. Pea or bajri flour ... ... 12 Dripping or ghee 4 This quantity is sufficient for 1,000 baits. The dripping or ghee is melted, and the whole mixture worked into a paste or dough, rolled out, and cut up into small squares. Other barium compounds are as follows : Barium Chlorate (Ba(ClO 3 ) 2 ,H 2 O) White, crystalline, soluble in water, and used in pyrotechnics and dyeing. Barium Chromate (BaCrO 4 ) A heavy, yellow, crystalline body, insoluble in water, and used in compounding pig- ments and making safety matches. Barium Cyanide (Ba(CN) 2 ) White, crystalline, and soluble in water and alcohol ; used in metallurgy. Barium Fluoride (BaF 2 ) A white powder, used in enamel-making. All the soluble salts of barium are poisonous. BARK BASALT 51 BARK The outer rind of trees, the principal ones being the cork-bark (see Cork), the oak bark used in tanning, and the Peruvian bark from which quinine, etc., is prepared. BARM The yeasty top which forms on fermenting beer, used as leaven in bread-making and for other fermentations. (See Yeasts.) BAROMETERS Instruments devised for indicating the pres- sure and density of the air. They are made in various forms, of which the simplest consists of a straight glass tube closed at one end, filled with mercury and inverted with the open end in a tray of mercury. It is gene- rally assumed that the average ordinary density of the air is when, at sea-level and at a temperature of zero (o C.), the column of mercury in the tube stands at 760 millimetres, or 29^92 inches high. As the pressure or density of the atmosphere increases, the column rises, and as it diminishes the column falls. The normal pressure is about 147 pounds to the square inch. The space above the mercury, in the simplest form of a mercurial barometer, is practically vacuous, and is popularly known as the Torricellian vacuum. As the barometer measures the weight of the super- incumbent air, it necessarily follows that the higher the altitude the lower the barometer indication. In chemical investigations, gases are weighed or measured subject to the atmospheric pressure, and vary directly in density and inversely in volume with the pressure ; hence the necessity of recording the pressure and reducing the amount to a standard pressure, as also a standard temperature. (See Attenuation and Vacuum.) BARRILLA An impure sodium carbonate, somewhat like kelp, produced in Spain and the Levant by burning certain plants to ashes. These plants grow on the seashore and belong chiefly to the genus Salsola. BARWOOD (Camwood) An African red dye wood from the Baphita nitida, which contains 23 per cent, of red colouring matter soluble in hot alcohol, supposed to be identical with " santalin " (a crystalline red body obtained from sandal wood). BARYTES (Heavy Spar) See Barium. BARYTOCALCITE A mineral compound carbonate of barium and calcium of the composition BaCO 3 ,CaCO 3 . BASALT A dark-coloured form of felspar. 52 BASES (ALKALIES) BASES (ALKALIES) Bodies which combine with acids, thereby neutralizing their acidity, and forming salts. Originally, the compound known as potassium carbonate was obtained from the ashes of seaweed and was called alkali, a word of Arabic origin. By the term alkali is now meant something of exactly the opposite nature to acid. The common alkalies are named potash, soda, and ammonia. Potash (or potassium hydrate) is a combination of i atom potassium, i atom hydrogen, and i atom oxygen KHO. Potassium carbonate is a combination of 2 atoms potas- sium, i atom carbon, and 3 atoms oxygen K 2 CO 3 . Soda (or sodium hydrate) is a combination of i atom sodium with i atom hydrogen and i atom oxygen NaHO, and sodium carbonate (the essential constituent of common washing-soda) is Na 2 CO 3 . Potassium and sodium in combination with oxygen alone form oxides, and their formulae are as follows : K 2 O and Na 2 O. It is by combination of these oxides with water that the respective hydrates (or, as they are alternatively called, hydroxides) are formed. For example, a molecule of the potassium oxide combining with a molecule of water gives 2 molecules of potassium hydrate, thus : K 2 O + H 2 O = 2KHO. Ammonium hydrate is a combination of i atom nitrogen, 5 atoms hydrogen, and i atom oxygen NH 4 HO. These oxides and hydrates are all soluble in water. Barium oxide (BaO), when combined with water, forms barium hydrate as follows : BaO + H 2 O = BaH 2 2 . In this case, i part or molecule of the barium oxide (which is insoluble in water) enters into combination with i part or molecule of water, and produces i part or molecule of barium hydrate (which is soluble in water to some extent). A hydrate is therefore a combination of an oxide of a base or metal and the elements of water. These alkaline bodies are all more or less soapy to the feel when dissolved in water, and they have the opposite action on colours to acids that is, they turn vegetable red colours to blue colours. They are also classified as bases; but there are many other kinds of bases, all of which have the property of entering into chemical action with acids to form compounds which are called salts, including all^those organic bodies BASES (ALKALIES) BAY OIL 53 BASES (ALKALIES) (Continued) which are derivatives of ammonia or may be viewed as such, including the amines and the alkaloids. The same term is used to include the derivative com- pounds of the phosphorus, arsenic and antimony analogues of ammonia; the phosphines, arsines and stibines being de- rived by the exchange of hydrogen for radical groups such as CH 3 and C 2 H 5 in the compounds known as phosphor- etted hydrogen, arseniuretted hydrogen and antimoniuretted hydrogen respectively ; so that there result for examples triethyl phosphine, P(C 2 HJ 3 , trimethyl arsine, P(CH 3 ) 3 , and trimethyl stibine, Sb(CH 3 ) 3 , all of which are of more or less basic character. BASIC SLAG See Iron and Slag. BASSIA OIL (AND FATS) Obtained from trees of the Bassia species which grow in India and the East Indies, including " Mowrah seed oil," " Illipe butter," " Shea butter," " Njave oil," etc. (See Shea Butter.) BASSORA GUM From the Acacia leucophlaa. BASSWOOD (LINDEN) OIL From Tilia americana, like cotton- seed oil, containing glycerides rich in butyric acid. BATHBRICK Scouring bricks made of calcareous and siliceous earth obtained from deposits at Bridgwater and other places. BATHSTONE A natural formation of rock chiefly composed of calcium carbonate, and largely employed in the con- struction of buildings. BATTERIES (Storage) See Electricity. BATTERIES (Electrical) See Electricity. BATTERY A stamping mill used in mining. BAUXITE Natural hydrated aluminium oxide (A1 2 O 3 2H 2 O). There are several varieties of this mineral viz., a white quality containing some 60 per cent, alumina, a little iron, and no silica, which is used for making aluminium salts and alum ; a red variety of about the same alumina content but containing little silica, used for manufacturing metallic aluminium ; and another white kind containing only 45 per cent, alumina and much silica, which is used more for making refractories. (See Aluminium.) BAY OIL (Myrcia oil) A yellowish essential oil distilled from the leaves of Myrcia acris, of sp. gr. 0*965 to 0-995. The yield is from 2 to 3 per cent., and the oil is used in 54 BAY OIL BEER BAY OIL (Continued) perfumery and for making bay-rum. It contains terpenes and eugenol. BAY-BERRY WAX See Waxes. BAY SALT is produced by the evaporation of sea- water. BEAKERS are thin glass vessels made of such a quality as to withstand exposure to heat, cylindrical in shape with flat bottoms, and are sometimes provided with a lip to facilitate the transfer of contents. They are of various sizes, from quite small ones up to a capacity of a litre (1,000 c.c.) and more ; and are not only used for holding and heating liquids, but also for effecting many chemical operations. BEECHWOOD CREOSOTE A colourless or faintly yellow creosotic liquid obtained from the tar resulting from the distillation of beechwood, and containing, amongst other phenolic constituents, an active liquid named creosol (C 8 H 10 O 2 ), which boils at 220 C. It is soluble in alcohol and ether, and to some extent in water; sp. gr., 1-080; boiling-point, 2O5-22o C. It is preferably prepared from Fagus sylvatica or F. fermginea. BEER Infusion of malt, flavoured with the bitter of hops and fermented with yeast, containing from 2 to 6 per cent, of alcohol. Porter and stout are beers, owing their dark colour and special flavour to the employment of added colouring matters or " high dried " malt. Any farinaceous grain can be used, but barley is generally preferred. It is allowed to germinate, and is subsequently kiln-dried, con- verting it thereby into malt, and the higher the temperature at which it is dried the darker becomes the colour. By the process of germination, diastase is formed from the albumi- noid part of the grain, and the starch is converted by the diastase into dextrin and sugar, which in their turn are converted into alcohol by the subsequent fermentation with yeast. This, however, is not allowed to proceed to completion, so that some sugar may be left in solution after the fermented wort is separated from the yeast. The strength and flavour of the beer admit of endless variation, strong beers containing more alcohol than mild ales, and substantial ones having more "body" that is, being richer in malt extract. In brewing, the character of the water is of great im- portance, and it may be said that the purer it is the better : hard waters, however, can be used in making pale ales, but soft waters are better for stouts and porter. BEER BELL-METAL 55 BEER (Continued) While by the action of enzymes, a certain amount of ready-formed soluble carbohydrates are formed during the malting process, it is in the mash tun that diastase exercises its fuller function of saccharifying the starch of the malt sometimes supplemented by the addition of other starchy substances, such as maize, rice, barley into dextrin, malto- dextrin, and maltose. When starchy bodies are added as mentioned, they are first of all gelatinized by heating with or without a little malt, in an apparatus styled a converter, thus facilitating the action of the diastase. The purity (cultivation) of the yeast is of great importance, and much more care is taken now than in former years in scientific brewing to prepare purer cultures, so as to avoid the presence in the beer of those undesirable products which are produced by otherwise associated ferments, (See Malt.) BEESWAX See Waxes. BEET-SUGAR (C 12 H 22 O n ) Sugar extracted from beet-roots, which contains from 14 to 18 per cent, of cane sugar. (See Sugar.) BECQUEREL RAYS A study of the radiations emitted by phosphorescent bodies led Becquerel to the discovery that certain salts of uranium evolve rays which possess the property of affecting a photographic plate, and that of rendering the surrounding medium an electrical conductor. These rays, like the cathode rays, travel in straight lines and can traverse wood, paper, and some metals, including aluminium. (See Radio-activity.) BEGKASSE The waste pulp left after expressing sugar from sugar-canes, which finds use as a fuel. BELLADONNA OIL is expressed in Wurtemberg from the seeds of Atropa belladonna, and used for illumination and other purposes. The poisonous principle is said to be retained in the marc, which therefore cannot be used as cattle food. (See Atropine.) BELLITE See Explosives. BELL- JAR A glass jar of bell shape used for covering other vessels and for other purposes. (See Desiccator.) BELL-METAL An alloy of about 77 per cent, copper arid, 23 per cent. tin. (See Alloys.) 56 BENGAL FIRE BENZINE BENGAL FIRE A mixture of realgar (arsenic disulphide), sulphur, and nitre. BENZALDEHYDE (C 7 H 6 O or C 6 H 5 CHO) A colourless liquid of high refractive character and almond-like odour, soluble in alcohol and ether, having a sp. gr. of 1-05 and a boiling-point of 179 C. It is used in perfumery and for flavouring purposes. (See Glucosides.) BENZAMIDE See Amides. BENZAMINE HYDROCHLORIDE An organic compound used in medicine. BENZAMINE LACTATE (C 15 H 21 NO 2 .C 3 H 6 O 3 ) A white crystalline organic compound, soluble in water and alcohol, used in medicine and for the production of eucaine. BENZENE (C 6 H 6 ) A liquid hydrocarbon of sp. gr., 0-8784, and boiling-point, 797 C., obtained from the products of the distillation of coal. It is colourless, inflammable, of characteristic odour, soluble in alcohol and ether, and can be prepared in a crystalline state by freezing the pure liquid. It is an excellent solvent of resin and fats, and in a crude form is extensively used as a fuel for motors, also as a primary material in the manufacture of aniline dyes and many other carbon compounds. It is the initial member of a series of hydrocarbons, and can be obtained pure by distillation of a mixture of benzoic acid and lime. (See Hydrocarbons.) It is the chief constituent of the commercial product known as " solvent naphtha." '(See Coal.) By oxidation with potassium permanganate it is slowly converted into formic and oxalic acids. BENZIDINE (C 12 H 12 N 2 or C 6 H 4 NH 2 NH 2 C 6 H 4 ) A derivative of diphenyl, being a greyish-yellow, crystalline, basic body which melts at 127 C. and boils at 400 C. It is soluble in alcohol, ether, and hot water, and is of importance in the colour industry, because the so-called " substantive " colours, which dye unmordanted cotton directly, can be obtained from it. Congo red and chrysamine belong to this group of colours. Benzidine is prepared by reducing nitrobenzene with zinc dust in alkaline solution, or by the electrolysis of that substance, followed by distillation. BENZIL (C 1 4H 10 O 2 ) A yellow crystalline compound obtained by oxidizing benzoin with nitric acid, which melts at 95 C., and is soluble in alcohol and ether. BENZINE is not synonymous with benzene, but is a light petroleum oil. Persian benzine contains only 2-32 per BENZINE BENZYL CHLORIDE 57 BENZINE (Continued} cent, benzene, and this is associated with toluene, xylene, and many other hydrocarbons. BENZOIC ACID (C 7 H 6 O 2 or C 6 H 5 ,CO 2 H) can be obtained in colourless, needle-shaped crystals from gum benzoin by sublimation and occurs naturally in the resins named " dragon's blood " and balsam of tolu, although it is chiefly made from toluene by an oxidation process. It is but little soluble in cold water, dissolves readily in hot water, and is soluble in alcohol and ether ; sublimes readily ; melts at 120 C., and boils at 250 C. When heated in admixture with lime it is decomposed, benzene and carbon dioxide being produced. It is used in the manufacture of aniline blue, possesses antiseptic properties, and finds use also in perfumery and in medicine. BENZOIC ANHYDRIDE (C 14 H 10 O 3 or (C 6 H 5 ,CO) 2 O) A crys- talline substance soluble in water and analogous to acetic anhydride ; melting-point 39 C. BENZOIN (C 14 H 12 O 2 ) A glistening, yellowish, crystalline body which melts at 134 C., and is polymeric with benzaldehyde. BENZOIN GUM is a resin which flows from the bark of Styvax benzoin, a tree that grows in Sumatra, Borneo, Java, and Siam. It has a pleasant smell, melts when heated, is soluble in alcohol, and is a mixture of several resins containing benzoic and cinnamic acids, which can be dissolved out of it by boiling water, or extracted to some extent by heating (sublimation). It is used as a source of the acids it contains and in varnish-making. BENZOL (Solvent naphtha) Commercial benzene, contain- ing benzene (C 6 H 6 ), toluene (C ? H 8 or C 6 H 5 (CH) 3 ), xylene (C 6 H 4 .2CH 3 ), etc. It is a nearly colourless liquid of sp. gr. 0-878, boiling at about 80 C., soluble in alcohol and ether, and is obtained from the distillation of coal-tar and by scrubbing coke-oven gas. (See Coal.) BENZOYL PEROXIDE (C 14 H 10 O 4 ) A crystalline, explosive, oxidizing and drying agent, which melts at 106 C. BENZO-NAPHTHOL, or NAPHTHOL BENZOATE (C 6 H 5 CO 2 C 10 H 7 ) A white substance used medicinally as an intestinal antiseptic, when it splits up into naphthol and benzoic acid. It melts at 107 C., and is soluble in hot alcohol. BENZYL CHLORIDE (C 6 H 5 CH 2 C1) A colourless aromatic liquid, prepared by chlorinating boiling toluene; sp. gr.. 1-1027, an d boiling-point 179 C. ; used for the preparation of oil of bitter almonds and certain dyes. 58 BERBERINEBILE BERBERINE (C 20 H 17 NO 4 ,H 2 O) A crystalline alkaloidal body without marked physiological properties found present in the roots of Hydvastis canadensis. It is soluble in water and alcohol ; melting-point 145 C. BEEGAMOT The yellowish-green essential oil of the Citrus bergamia, which grows in South Europe. It contains ter- penes, has a sp. gr. of 0-88 1 to 0*885 '> refractive index, i -465 to i -470 ; optical rotation +9 to +15; and is used in perfumery. BERYL A mineral consisting of a double silicate of aluminium and glucinum. BERYLLIUM See Glucinum. BERZELIANITE A rare mineral, consisting of copper selenide associated with silver, thallium, and iron. BESSEMER PROCESS See Iron. BETAI'NE (C 6 H U NO 2 ,H 2 O) A colourless alkaloidal body of crystalline nature contained in molasses of beet sugar. BETA-NAPHTHOL (C 10 H 8 O or C 10 H 7 OH) is contained in and obtained from coal-tar in the form of white, glistening, crystalline plates with a phenolic odour. It melts at 122 C., and boils 282 C., can be purified by sublimation, and is soluble in alcohol and ether. It constitutes the starting-point from which a number of dyes are obtained, and is used medicinally as an intestinal antiseptic in diarrhoea of children. BETEL A mixture of the leaves of the betel pepper, Piper betel L., with the fruit of the Areca catechu, used in tropical Asia as a masticatory, and in medicine. BICHROMATES See Chromium. BILE is the secretion of the liver as discharged into the duodenum, and plays an important part in the process of food digestion. It is a viscid liquid of yellowish-green colour, which becomes more yellow on dilution, of sp. gr. about 1*02, and owes its viscidity to the presence of a quantity of mucus derived from the gall-bladder. It consists of more than 90 per cent, water, but the biliary matters proper, contain taurocholate and glycocholate of sodium, several colouring matters (the chief of which are bilirubin and bilifuscin (C 16 H 20 N 2 O 4 ), also a small quantity of cholesterin, lecithin, and choline. Glycocholic Acid (C 26 H 43 NO 6 ), as obtained from the bile, when pure, crystallizes in long silky needles, which are freely soluble in hot water ; melting-point 133 C. Taurocholic Acid (C 26 H 45 NSO 7 ) contains sulphur as one of its constituents. Both of these acids can be made to. BILE BISMUTH 59 BILE (Continued) yield Cholic Acid (C 20 H 40 O5), and that substance in turn is said to yield a fatty acid of the stearic series when oxidized. Bilirubin (C 16 H 18 N 2 O 3 ) has a brilliant red colour, but quickly changes into the green biliverdin (C 16 H 18 N 2 O 4 ), when bile is exposed to the air. It is the bile that gives colouring matter to the faeces. BIOPLASM, sometimes called protoplasm, is the most elementary living matter in the animal and vegetable kingdoms, being the germinal substance from which all living creatures build up their structures by assimilation. It is of an albuminous character. BISMUTH (Bi) Atomic weight, 208 ; sp. gr., 9-823 : melting- point, 271 C. Bismuth occurs in nature mainly in the metallic state, also combined with oxygen as bismuth ochre (Bi 2 O 3 ), with sulphur as bismuth glance (Bi 2 S 3 ). and with tellurium as tetradymite (a natural telluride found in Arizona, California, etc.). It is also found as bismuthinite (a sulphide of the metal occurring in association with gold in Rowan Co., N.C.), as bismuth-gold (Au 2 Bi) at Maldon, Victoria, and in association with antimony in kobellite t hauchecornite and chiviatite. It is a lustrous, white, brittle metal of a reddish tinge, forming beautiful crystals, and forms alloys with other metals, of which one of the best known is Wood's fusible metal, which is made of 4 parts bismuth, 2 of lead, i of tin, and i of cadmium, and melts at 6o'5 C. It is made from its metallic ores by a process of roasting to remove sulphur, and is subsequently refined when re- quired in the pure state, by conversion into nitrate and reduction by heating with charcoal. Among its compounds are two chlorides (BiCl 2 and BiCl 3 ), two or more oxides, of which the trioxide (Bi 2 O 3 ) alone is of any commercial importance ; it is a yellowish insoluble powder of sp. gr. 8'2, prepared by heating the carbonate or nitrate, and is used in the manufacture of crystal glass to replace lead oxide. When acted upon by acids the oxides give salts, including bismuth nitrate (Bi(NO 3 ) 3 ) and bismuth sulphate (Bi 2 (SO 4 ) 3 ). Bismuth subnitrate, (BiO)NO 3 ,H 2 O (a heavy white powder, used in medicine and in preparing enamels, fluxes, and cosmetics), is prepared by adding bismuth nitrate to water, which decomposes it, as represented thus : Bi (N0 3 ) 3 + 2H 2 = (BiO)N0 3 ,H 2 + 2HNO 8 . Bismuth sulphide (Bi 2 S 3 ) is a black insoluble body. 60 BISMUTH BLEA CHING BISMUTH (Continued} Bismuth chromate (Bi 2 O 3 .2CrO 3 ) is a yellow amorphous substance used as a pigment. Many of the bismuth salts are used in medicine and are for the most part insoluble in water; among others used in medicine are the betanaphtholate (orphol) (Bi(C 10 H 6 OH) 3 ); salicylate(Bi(C 7 H 6 O 3 ) 3 4H 2 O); a subsalicylate(Bi(C 7 H 5 O 3 ) 3 Bi 2 OJ, and the tribromophenylate (xeroform) (Bi 2 O 3 (C 6 H 2 Br 3 OH)). BISMUTITE A natural basic bismuth carbonate which yields about 90 per cent, of the oxide Bi 2 O 3 ; found in auriferous quartz in the Transvaal. BITTERN The mother-liquor of sea-water left after crystal- lization of its salts, formerly used as a source of bromine. BITTERS are bodies extracted from vegetable productions, and include : 'quassia, from quassia wood ; wormwood, from the herb of that name ; aloe, from the juice of the plant ; angostura, from bark ; orange, from the peel ; acorus, from the root of the common sweet flag ; cascarilla, from bark ; camomile, from the flowers ; colocynth, from the fruit (Citrullus colocynthis). BITUMENS Soft deposits constituted of hydrocarbons of complicated composition, often found in association with petroleum as, for example, at Trinidad. They are soluble in carbon disulphide and Russian turpentine, and are largely used for paving purposes, making varnishes, and for lining and cementing water-tanks, etc. (See Asphalt.) BLACK ASH The crude sodium carbonate as made in the Leblanc process. (See Alkali Trade, and Sodium carbonate. BLACK-BAND See Iron. BLACK-DAMP See Carbon. BLACKING is commonly made from bone-black, sugar, and oil, with the addition sometimes of a little vinegar or strong sulphuric acid : there are, however, many recipes. BLACKSTRAP See Molasses. BLANC FIXE See Barium sulphate. BLACK-LEAD See Carbon. BLEACHING An operation largely employed in the arts, a number of chemical agents being used therefor. Bleaching-powder (see Chlorine) is used on an immense scale, the materials to be bleached, such as calicoes and BLEA CHING BLOOD 61 BLEACHING (Continued) other fabrics, rags for paper-making, etc., being first steeped in a dilute solution (2 to 2 J per cent, strength) of the bleaching-powder and then in dilute acid. In the case of calico, the fabric is first of all well washed, and boiled successively with lime-water, much dilute sulphuric acid, and weak caustic soda, to remove the weavers' dressing, greasy and resinous matters, etc. Hypochlorous acid (HC1O), which may be said to act in the same way (being practically the active principle of bleach- ing-powder), also serves the same purposes, readily giving up oxygen. It is, however, a somewhat explosive substance and undergoes rapid decomposition on exposure to the air. At one time, particularly in France, a solution of sodium hypochlorite was extensively used for bleaching, being prepared under the name of Eau de Javelle. Sulphur dioxide (SO 2 ) also exhibits powerful bleaching effects, and is largely used for bleaching straw, woollen, and silk goods, isinglass, sponge, and other articles which would be injured by the use of chlorine compounds. To effect this, they have to be moistened and exposed to its fumes as generated by burning sulphur or, alternatively, treated with a dilute solution of the gas dissolved in water (sulphurous acid). Peroxide of hydrogen or hydrogen dioxide (H 2 O 2 ) is a very valuable bleaching agent, readily parting with its second constituent atom of oxygen, and has the great advan- tage of being perfectly innocuous to operators and goods. It is largely used in respect of delicate fabrics, straw goods, human hair, ivory, etc. The old practice of bleaching linen and other materials, but particularly hempen and flaxen goods, by exposing them to the air is referred to in the article on Light, and is probably due to the production of hydrogen dioxide by sunlight action on moisture and oxygen. BLEACHING POWDER See Chlorine and Alkali Trade Chart. BLENDE See Zinc. BLOOD is built up from the digested food and serves to supply all parts of the organism with fresh nutrient materials to replace those worn out by the processes of life, and it also dissolves and carries away the excretory products. It is by the medium of the blood that the great process ot oxidation through respiration is effected. It is alkaline in reaction, and has a sp. gr. ranging from 1*055 to 1*062, its temperature in the living body being about 37-8 C. (100 F.). 62 BLOOD BONES BLOOD (Continued) Besides the other small chemical differences between arterial and venous blood, there is the greater divergence in the matter of oxidation dependent upon the oxygen-carry- ing capacity of the red colouring matter (haemato-crystalline or haemoglobin), which contains iron and consists of a combination of hematine (C 32 H 3o FeN 4 O 3 ) with a certain albuminous substance. Blood contains seralbumin, fibrin, and globulin in solution, together with a great number of other substances more or less definitely ascertained in addi- tion to its saline constituents. (See also Fibrin and Serum.) The clotting of blood is accompanied by an enzyme found therein named thrombin. BLOOD ALBUMIN (Seralbumin) Prepared from the serum of the blood of animals, finds use in commerce in connec- tion with printing colours on calico fabrics. It is contained in blood to the extent of about 0*08 per cent, the serum itself amounting to about 48-16 per cent. BLOOD-STONE A variety of jasper (native silica, SiO 2 ). BLOW-PIPES Appliances for intensifying the heat of flame by blowing air into admixture with the burning gas. As to the character of the blow-pipe flame, see Burners. BLUE STONE and BLUE VITRIOL Common names for copper sulphate. (See Copper.) BOILED OIL (blown oil) See Linseed oil. BOILING-POINT The highest temperature at which any liquid can be converted into vapour at the standard pressure of 760 mm. of mercury; or, the temperature at which its vapour pressure is equal to the atmospheric pressure. BOLE A sort of clay coloured with iron. Armenian bole is of a bright red colour; other kinds are yellow or yellowish-red. BONES Dry bones contain about 30 per cent, of ossein, which, when dissolved in water, yields gelatin, and the following table gives the average composition : Water and ossein ... ... 30 to 34 per cent. Calcium phosphate ... ... 45 to 52 ,, carbonate ... ... 6 to 14 ,, fluoride i to 2 Magnesium phosphate ... 0-8 to 1-2 Other salts traces Bone-earth (bone-ash) contains about 87 to 88 per cent, calcium phosphate (Ca 3 (PO 4 ) 2 ), 9 per cent, calcium carbo- BONES BORON 63 BONES (Continued) nate, 3 per cent, calcium fluoride, and 1-7 per cent, magnesium phosphate. BONE-BLACK An impalpable form of carbon (prepared by burning bones, and subsequently dissolving out the calcium and other mineral salts by means of acid applications), used for decolorizing solutions, as in sugar refining. (See Carbon.) BONE-MEAL See Phosphorus. BONE-OIL See Dippel's Oil. BORACIC ACID See Boron. BORACITE See Boron. BORAX See Boron. BORDEAUX MIXTURE A liquid insecticide and fungicide made from copper arsenite ; used in orchards, vineyards, etc. BORNEOL, or SOLID CAMPHOR OF BORNEO (C 10 H 18 O or C 10 H 17 OH), is found in cavities in the trunk of old trees of the order Dryobalanops camphora. It consists of small, colour- less crystals (resembling ordinary camphor and pepper in odour), which melt at 208 C. It is nearly allied to ordi- nary camphor, from which it can be prepared by reduction with nascent hydrogen C 10 H 16 O + 2H = C 10 H 18 O. It is used in medicine and in the celluloid industry. (See Camphor. ) BORNITE A mineral double sulphate of copper and iron (3Cu 2 S,Fe 2 S 3 ). BORON (B) and its compounds Atomic weight, n. Boron occurs naturally in a number of combinations, one of the best known being tincal, a crude borate of sodium or borax (Na 2 B 4 O 7 ioH 2 O), and this in a purified form is largely used for cleansing and other purposes. Borax is found naturally in Thibet, California, and elsewhere. In com- bination with calcium, boron is also found in the forms of boracite and colemanite or borate spar (Ca 2 B 6 O u ), and as ulexite (Ca 2 B 6 O u ,Na 2 B 4 O 7 ,i6H 2 O), a compound borate of cal- cium and sodium found in Nevada and California. The composition of some borate minerals, as taken from a pamphlet recently issued by the Imperial Mineral Resources Bureau, is as follows : 6 4 BORON (Continued) BORON Colemanite. Ulexite. Boracite. (California.) (Chili and Peru.) (Asia Minor.) Boric acid 40-19 44-38 45'89 Lime... 31-89 16-14 30-62 Magnesia 1-50 0-91 0'53 Iron and alumina . . . 0'62 0-48 0-98 Soda 6-50 Sodium chloride 7-46 Carbon dioxide 8-53 Sulphur trioxide 0-26 3*35 I-2 5 Water and organic matter 5-83 16-25 17-09 Insoluble matter II-I8 471 3 '64 Total 100-00 100-18 100-00 In the elemental state, boron is a soft greenish-brown powder, but it can be obtained in almost colourless crystals having a density of 2-63. The melting-point of boron lies between 2,200 and 2,500 C. There are several methods of preparing this element, one of which consists in heating potassium in the vapour of boron trichloride as shown by the equation 3K + BC1 3 =3KC1 + B, and another in heating metallic potassium or sodium in admixture with boron trioxide 6K + 2B 2 O 3 = 3K 2 O 2 + 46. The purest boron is said, however, to be obtained by the reduction of boron trichloride with hydrogen in the high- tension electric arc. When heated strongly in the air boron burns and combines with both oxygen and nitrogen, forming the trioxide and nitride (B 2 O 3 and BN). Boron is sometimes added to metallic castings, especially those of aluminium and nickel, to strengthen them. Boric or Boracic Acid (B(HO) 3 ) is found naturally in the water and steam jets of volcanic eruptions in Tuscany and elsewhere, and is obtained commercially from such sources. It is soluble in water and in a purified condition it finds BORON AND ITS COMPOUNDS 65 BOEON (Continued) many medicinal applications, while it is also largely used in glass-making and metallurgy as a flux, and as a pre- servative agent of perishable articles. Borax can be made from boric acid by adding anhydrous sodium carbonate to a boiling solution of the acid, when the following change takes place 4 B(HO) 3 + Na 2 CO 3 = Na 2 B 4 O 7 + 6H 2 O + CO 2 . That is to say, borax is produced in solution, and carbon dioxide is evolved, and from the liquid the borax is crystal- lized out in combination with water (Na 2 B 4 O 7 ioH 2 O). It occurs naturally in California and elsewhere, and only requires purification by recrystallization. It is, however, chiefly produced from the Bolivian deposits of calcium borate by boiling the powdered mineral in water and addition of soda-ash Ca 2 B 6 O n + 2 Na 2 CO 3 = 2CaCO 3 + Na 2 B 4 O 7 + Na 2 B 2 O 4 . That is to say, calcium carbonate is precipitated and the borax is crystallized out of the solution, leaving the sodium metaborate (Na 2 B 2 O 4 ) in solution, and this is afterwards converted into a further quantity of borax by treatment with carbon dioxide 2 Na 2 B 2 O 4 + CO 2 = Na 2 C0 3 + Na 2 B 4 O r Borax is used as a food preservative ; also in the textile and tanning industries, as a sanitary reagent, and in ceramics, being prepared in various forms, such as powder, crystals, fused state, etc. When crystalline borax is heated, it loses its associ- ated water and passes into a fused glassy mass, which pos- sesses the power of dissolving many metallic compounds, so that it is used in the laboratory for analytical purposes, the colour which is communicated to the bead of fused material being indicative of the substance under examina- tion. For example, using a looped platinum wire, it can be made to take up a small quantity of borax, which can then be fused so as to make a clear bead in the loop by heating and dipping afresh in the borax whilst still hot until it is sufficiently large. If such a bead be touched with a com- pound of cobalt, it will, upon remelting and subsequent cooling, be found to have an azure or deep blue colour, according to the quantity of cobalt used. Manganese compounds communicate a violet, lilac, or 5 66 BORON BRANDY BORON (Continued) purple colour if the bead be. heated in the outer (oxidizing) flame of a blow-pipe ; but this colour is lost if the bead be heated in the inner (reducing) flame, owing to chemical changes that occur under these different circumstances. Borax is a valuable flux, and is used in manufacturing pottery glazes and enamels, also as a glaze for linen and paper. It is also employed in tanning, in the manufacture of glue, soap, and glass, and as a food preservative. Boron trichloride (BC1 3 ) is produced by heating boron in a current of dry chlorine, and is a mobile, colourless liquid, boiling at a little, over 18 C. It is decomposed by water, forming boric and hydrochloric acids. There is a corresponding trifluoride of boron. Boron Nitride is a white amorphous powder, which, when boiled in caustic alkaline solution, is decomposed with the production of ammonia BN + 3KHO = KBO 3 -H NH Boron triethyl (B(C 2 H 5 ) 3 ) is a spontaneously inflam- mable liquid, and the analogous boron trimethyl (B(CH 3 ) 3 ) is a gas of very unpleasant character. BOTTLES are generally made of glass, but some are made of gutta-percha for holding liquids that act upon glass, such as hydrofluoric acid. BOYLE'S LAW OF PRESSURE See Gases. BRAIN-MATTER contains from 80 to 90 per cent, water, the tissue being a mass of colloid matter of which the envelope is of an albuminous character, whilst the con- stituent parts are of very complicated chemical consti- tution, comprising a number of phosphorized substances including lecithin (which yields glycerophosphoric acid (C 3 H 9 PO 6 ) and a base named neurine (C 5 H 13 NO) upon hydrolysis); a so-called cerebrine group of substances which appear to be of a glucoside nature, cholesterin (C 26 H 44 O), and a number of extractive matters. BRANDY Real spirits of wine as prepared by the distillation of fermented wines (generally coloured with burnt sugar or caramel) BRA NNERITE BROMINE 67 BRANNERITE A new uranium mineral, obtained from gold placers in Idaho ; found in the pegmatites. It is described as a complex titanate of uranium, associated with smaller quantities of rare earths, including as much as 50 per cent, of uranium oxides. BRASS See Alloys, Zinc, and Copper. BRAXJNITE A manganese ore of the composition 3Mn 2 O 3 , MnSiO 3 that is, a compound oxide and silicate, occur- ring in Sweden, the United States of America, and India. BRAZIL-NUT OIL See Castanha Oil. BRAZIL WOOD DYES are red and orange, and are extracted from the wood of the Casalpina crispa by boiling water. They are used for dyeing articles of silk and wool. BREWING See Beer. BRICKS are made from clay or the mixture of clay and sand called loam, as also marl (which consists of clay and lime), by moulding and baking. BRITANNIA METAL See Alloys, Antimony, and Tin. BRITISH GUM See Starch. BROMINE (Br) Atomic weight, 80; sp. gr., 3-188 at o C. ; boiling-point, 58*7 C. Bromine is found in sea-water in combination with potassium, sodium, and magnesium, and more abundantly in certain mineral waters and salt springs. The Stassfurt saline deposits of Germany contain it (com- bined with magnesium) in larger amount in carnallite, from which it is chiefly made. In the manufacture of potassium chloride from carnallite, there is produced a mother-liquor containing about J per cent, of bromine as magnesium bromide, and the bromine is obtained from this salt by heating it with superheated steam, on admixture with manganese dioxide and sulphuric acid, or by decomposition with chlorine (which replaces it in combination), the bromine being set free in vaporous state and condensed in cooled stoneware coils. During the recent war France obtained a considerable quantity of bromine from deposits in the salt marshes or lagoons of Tunisia. Bromine is a heavy, mobile liquid of a red-brown colour and strong, unpleasant smell. It gives off vapour of the same colour when exposed to the air that is to say, it is very volatile. At - 7 C. it solidifies to a crystalline mass. It is very poisonous, has a strong corrosive action on the skin, and is soluble in water, alcohol, and ether. 68 BROMINE-BRUCITE BROMINE (Continued) Bromine is used in the dye industry, in organic synthesis, and the production of bromides. The soluble salts, sodium bromide (NaBr), potassium bromide (KBr), and ammonium bromide are all used in the preparation of certain medicinal sedative mixtures. Hydrobromic Acid or Hydrogen Bromide (HBr), cor- responding to hydrochloric acid, is produced when a mixture of hydrogen and bromine vapour is burned or passed over a spiral wire of platinum maintained at a bright red heat. There are a number of other methods by which it can be produced. It is a colourless gas of pungent odour, which fumes in the air and is very soluble in water, the aqueous solution resembling one of hydrochloric acid in its general chemical behaviour. Bromic Acid (HBrO 3 ) is only known in solution, and it forms bromates corresponding to the chlorates by corre- sponding reactions, potassium bromate having the formula KBrO 3 . BROMITE Native silver bromide. BROMOFORM (CHBr 3 ) A colourless heavy liquid of sp. gr. 2-8887, soluble in alcohol and ether; corresponding to chloroform and iodoform ; used in medicine, etc. BROMYRITE Natural silver bromide (AgBr) containing 57 per cent, of silver, found in New Mexico and Nevada. BRONZE See Alloys, Copper, and Tin. BRONZE BLUES Forms of Prussian blue. BRONZE POWDERS Used for japanning and other decorative applications, and made of many shades, are compounded of alloys of various metals copper, zinc, iron, tin, vanadium, etc. reduced to powder, with or without admixture with other compounds, according to the desired colour and properties. BROOKITE See Titanium. BRUCINE (C M H 26 N 2 O 4 ,4H 2 O) A white crystalline, nitro- genous base, soluble in alcohol, accompanying strychnine in nux vomica. (See Nux Vomica.) BRUCITE A native form of magnesium hydroxide (Mg(HO) 2 ) found in serpentine rocks in Shetland and Texas. BRUNSWICK BLACK BURNERS 69 BRUNSWICK BLACK is prepared by melting together asphalt and boiled linseed oil in the proportions of 2 to i and adding two parts of turpentine to the mixture upon cooling. BRUNSWICK GREEN See Copper. BRUSHITE A natural hydrated calcium phosphate (CaHPO 4 , 2H 2 O) found in the guano of Aves Island and Sombrero. BUCHNER FUNNEL See Filters. BULBS See Potash Bulbs ; also Organic Analyses. BUNSEN BURNER See Burners. BURETTE A graduated glass tube, open at the top and drawn out below, fitted either with a glass stopcock, or rubber tubing and a pinch-cock, for delivering measured quantities of liquids. (See Volumetric Analyses.) BURGUNDY PITCH, of genuine character, is made by melt- ing frankincense (Abides resina) in water and straining it through cloth, but common rosin coloured with palm oil is said to be often substituted for it. It is a yellowish-brown, brittle, resinous substance, of aromatic odour, soluble in hot alcohol, and is used in medicine. BURNERS Gas-burners used in laboratories are of various types, according to the application that is to be made of them, apart from those used for illumination. Fish-Tail Burner This resembles the old-fashioned sort used for lighting rooms, the flame of which is like a fish- tail or bat's wing in general form. It is chiefly used in connection with the bending of glass tubes (see Glass Tubes), and may be attached directly to the gas-supply pipe running along the working bench of the laboratory, or fixed on an upright stand and connected therewith by means of a rubber tube. The luminosity of the flame is due to the imperfect combustion of the gas, and consequent production of minute particles of the carbon constituent in an incandescent form. Bunsen Burner This consists of an iron or brass tube fixed to a stand, and is fitted with a mechanical arrange- ment below, whereby air can be admitted in regulated amount into admixture with the gas before burning. The gas issues from a small jet at the base of the tube, and the air is admitted through several small holes also situate near its base, the amount of air being regulated by a movable disc of metal capable of closing these openings more or less as desired. In practice there is used about 70 BURNERS BUTTER BURNERS (Continued) i part gas to 2^ parts of air. By this admixture the heat is intensified, perfect combustion of the carbon of the gas, as also of the hydrogen, being secured, thus producing a practically smokeless blue flame. Such burners are often provided with a movable ring which fits on to the top of the burner tube, so that the flame may, when desired, be broken up and made to assume a rose or ring in the form of a number of small blue flames, instead of the one long vertical column of flame. Both of these forms are employed for heating liquids contained in flasks or beakers, or for heating solid substances contained in crucibles, dishes, etc.; also for applying heat to sand-baths, water-baths, and water-ovens. The flame of a Bunsen burner (like all ordinary flames) consists of two cones the inner one, in which heated but imperfectly burned gases exist ; and the outer one, where oxygen is in excess on the outside edge. Upon holding a bright copper wire across the flame so as to bisect (cut across) the inner one, the wire will become coated with black copper oxide at the outer edges, while that part in the centre will remain bright. If now the blackened part be placed in the inner cone, the oxide will be reduced again to the metallic state, parting with its oyxgen constituent to the gases in course of combustion. The outer area is consequently called the oxidizing flame, and the inner cone the reducing flame. When coal gas is burned in a current of air, water and carbon dioxide are among the products of its combustion. Blow-Pipe Burners See Blow-Pipes. BURNT ALUM A white porous salt of anhydrous alum made by heating ordinary alum to dull redness. BURNT LIME See Calcium. BUTANE See Hydrocarbons. BUTTER The fat of milk produced by churning, and consisting of about i real fatty matter and i butter-milk, which can be separated by melting ; the fatty matter being composed of palmitin, myristin, stearin, olein, and small quantities of other glycerides. It is also said to contain a small propor- tion of a vitamine. A recent investigation has shown that there is no material loss of the " fat soluble A," or growth vitamine, contained in butter during twelve months' storage at a temperature of 8 to 15 C. (See Vitamines.) BUTTER CACAO 71 BUTTER (Continued) It varies in composition within certain limits, but on average may be expressed as follows : Per Cent. Fat 86-85 Curd 0-59 Salt 102 Water IJ *54 lOO'OO One published analysis of dry butter is as follows : Per Cent. Palmitin, myristin, and other hard fats 53 -98 Olein 37*82 Butyrin and other constituents 8-20 100-00 When split up (hydrolyzed) butter yields, according to one authority, as follows : Palmitic acid, 18-23 per cent; myristic acid, 11-08 per cent. ; lauric acid, 16-40 per cent. ; stearic acid, 0-49 per cent.; oleic acid, 36-10 per cent.; caproic, caprylic, and capric acids, 3-23 per cent. ; butyric acid, 6*13 per cent. ; glycerine, 12-50 per cent. Butter has a sp. gr. of 0-926 to 0-940 ; a saponification value of about 227 ; and an iodine value of from 26 to 38. BUTYL ALCOHOL See Alcohols. BUTYLAMINE See Amines. BUTYRIC ACID (C 4 H 8 O 2 or CH 3 (CH 2 ) 2 CO 2 H) is produced by the oxidation of the corresponding butyl alcohol and in the butyric fermentation of sugar or starch being secondarily produced from lactic acid ; it also occurs in glyceric com- bination in butter, and communicates the so-called rancid odour to that substance when stale. It is found present in the free state in perspiration and in the secretions of certain insects. It is a colourless liquid of rancid odour when volatilized, boils at 162-4 C., an d nas a S P- g r - f '95& to 0-960. It is used in medicine and in varnish-making, etc. CACAO and CACAO BUTTER The seeds of Theobroma cacao and other members of the genus Stevculiacea of Africa, South America, West Indies, and some tropical parts of Asia, yield the nutritive substances cocoa and chocolate. The beans contain much fatty matter, and about i per cent, of theobromine (C 7 H 8 N 4 O 2 ), together with about 0-4 per !?2 CACAO CADMIUM CACAO and CACAO BUTTER (Continued) cent, of caffeine. The aroma of cacao is due to the presence of about 0*006 per cent, of linalool. The fat ranges from 50 to 56 per cent. ; has the consistence of suet, and consists of a number of fats, including about 40 per cent, stearine, about 31 per cent, oleic acid, and some proportion of theobromic acid (C 64 H 128 O 2 ). It is of sp. gr. 0*858 to 0-865, melts at from 32 to 34 C., has an iodine value of from 34 to 38, and a saponification value of 192 to 198. Cacao butter is used in pharmacy and in chocolate-making, and is distinct from cocoa-nut oil, which is yielded by the cocoa palm (Cocus nucifera). The shell is used in preparing cattle food. Chocolate is a preparation of roasted cacao beans without the abstraction of the butter, and always contains sugar and added cacao butter ; whereas cacao is the powder made from the roasted beans by pressing out part of the butter. CACODYL A methyl arsenide (As 2 (CH 3 ) 4 ) prepared by heating a mixture of arsenious oxide and potassium acetate. It is a colourless liquid, insoluble in water, of most offensive garlic-like odour, boils at 170 C., is extremely poisonous, and readily inflammable in the air. It combines with chlorine, and acts as an organo-metallic radical, forming, for example, cacodyllic acid, which may be represented as As(CH 3 ) 2 HO 2 . Cacodyllic acid is a colourless, poisonous, crystalline body, soluble in water and alcohol. CADAVERINE See Ptomaines. CADE OIL Obtained by the dry distillation of the wood of the Juniper us oxycedrus. A thick, clear liquid of burning, bitter taste, with a sp. gr. of from 0*98 to 1*06 ; soluble in alcohol and ether ; used in perfumery, medicine, and for making animal soap, etc. Its chief constituent is cadinene. CADINENE (C lp H 2 4) One of the sesquiterpenes (lyevoro- tatory) occurring in the oils of cade, betel, camphor, juniper, and olibanum. It is a viscous liquid of sp. gr. about 0-92, and boiling-point 274 C. CADMIUM (Cd) Atomic weight, 112 ; sp. gr., 8*642 ; melting- point, 320*9 C. Found naturally in the form of sulphide (CdS) in a rare mineral named Greenockite, and in a number of zinc ores, both as sulphide and carbonate. It is pro- duced in the process of extracting zinc from its ores, being found in the first fractions coming over when distilling them, partly in the metallic condition and partly as oxide, CADMIUM -CAJUPUT, OIL OF 73 CADMIUM (Continued) the proportion being about i part cadmium to 200 parts zinc. It can also be recovered from the bag-house con- densation products from lead and copper furnaces by an electrolytic process. An interesting property of this metal is its power of lower- ing the melting-point of certain alloys when incorporated in small proportion, thus making it useful in the manufacture of fusible plugs in sprinkler systems for fire prevention. The metal is of a bluish-white colour, and its com- pounds include the oxide (CdO), the chloride (CdCl 2 ), the bromide (CdBr 2 ), and the sulphide (CdS). The oxide is formed when the metal is burnt in the air ; the chloride is a soluble salt prepared by the action of hydrochloric acid upon the metal or its oxide ; the bromide is a yellow crystalline body soluble in water and used in photography ; and the sulphide, which is yellow in colour and insoluble in water, is used as a pigment in oil and water-colour painting. Cadmium nitrate (Cd(NO 3 ) 2 .4H 2 O) is a white soluble salt used for colouring glass and porcelain. CESIUM (Cs) Atomic weight, 132*8 ; melting-point, 26-5 to 28-45 C. A rare element belonging to the group of alkali metals, found in association with potassium and sodium in some minerals, including porphyrites, lepidolites, and carnal- lite, also in certain mineral waters ; but the most prolific source is pollux, or pollucite, in which it is contained in the form of a compound silicate of aluminium and caesium, yielding from 31 to 37 per cent, of the oxide Cs 2 O. It is a silver- white, soft, ductile metal, of sp. gr. I'Sy, and its compounds are very like those of potassium. CAFFEINE (THEINE) (C 8 H 10 N 4 O 2 ,H 2 O) is the alkaloidal principle of coffee (which contains varying proportions up to about i per cent), kola nuts, and tea (which contains from 2 to 4 per cent.). It melts at 236'8 C., and crystallizes from water -in white silky needles, having a slightly bitter taste. It is soluble in chloroform, not very soluble in cold water, but much more so in boiling water. It can be prepared from xanthine. (See Coffee.) CAJUPUT, OIL OF An essential oil used in medicine which is obtained in India by distillation with water of the leaves of the Melaleuca leucodendron L. It is of light green colour, soluble in alcohol and ether, containing cineol and terpinol. Sp. gr., 0-92 ; optical rotation, 10 to - 4 ; refractive index, 1-460 to i'466. (See Terpenes.) 74 CALABAR BEAN CALCIUM CALABAR BEAN The seed or bean of Physostigma venosum, said to contain an alkaloid named eserine, a solution of which has an action on the pupil of the eye the opposite to that which belladonna exercises that is, contraction instead of dilatation. CALAMINE See Zinc. CALAMUS OIL (oil of sweet flag) Distilled from the rhizome ofAcorus calamus, and used in perfumery, etc. It is a thick, yellowish, aromatic oil, soluble in alcohol and ether, of sp. gr. about 0*96, and refractive index about 1*5. CALCAREOUS SPAR Native crystallized calcium carbonate. CALCINATION Burning or incinerating operation, such as the conversion of chalk into lime by burning ; the burning of gypsum to rid it of water of composition ; or of organic matter such as bones, to obtain their ash. It is a process of oxidation largely resorted to, as a stage in the separation of metals from their ores. Such operations are carried out in the laboratory for the most part in crucibles, and in manufacturing operations in kilns and reverberatory and other furnaces. CALCITE (Calcspar) See Iceland Spar. CALCIUM (Ca) and its compounds Atomic weight, 40; sp. gr., 1-85 ; melting-point, 810 C. Calcium is not met with in nature in the metallic state, but chiefly in the form of carbonate (CaCO 3 ), in minerals such as limestone, marble, calcspar, and coral, in which and other forms it consti- tutes a considerable part of the earth's crust. In an anhydrous state, the sulphate exists as the mineral anhydrite (CaSO 4 ), and in other forms it exists as selenite, alabaster, and gypsum (CaSO 4 ,2H 2 O). Calcium is also found in nature in combination with fluorine as fluorspar (CaF 2 ). Calcium is a soft and whitish metal obtained in the metallic state by the electrolysis of fused calcium chloride. When heated in oxygen to 300 C., it inflames, and the lime which is thus produced is fused by the heat. Lime (calcium oxide, or so-called burnt lime, CaO) is a combination of calcium with oxygen, and is made on a very large scale by burning limestone with coal in kilns, when the carbonate parts with carbon dioxide and leaves lime or what is commonly known as quicklime behind. Or the limestone is baked alone in furnaces at a heat sufficiently great to break it up into quicklime and carbon dioxide gas CALCIUM AND ITS COMPOUNDS 75 CALCIUM (Continued) (CaCO 3 = CaO + CO 2 ), "producer gas" (see Producer Gas) being used for generating the heat. This quicklime (CaO) is a white and nearly infusible substance which, when mixed with water, forms the white powder known as calcium hydrate or slaked lime Ca(HO 2 ). Lime is used very largely in the making of glass, mortar, and cement, and in the preparation of lime-wash and dis- temper paints. It is also extensively used as the base in the manufacture of chloride of lime (bleaching-powder) ; also as a dressing for skins to remove grease and fur, and upon clayey soils to make the land more friable. Calcium Carbonate (CaCO 3 ) is almost insoluble in water, but dissolves readily when the water contains carbon dioxide, and the so-called temporary hardness of water is due to the amount thus held in solution but which is deposited when the water is boiled. The permanent hardness of water is due to the calcium sulphate and other mineral salts which are held otherwise in solution. In the form of arragonite it occurs naturally in ortho- rhombic crystals, and in calcspar as. hexagonal crystals, in both of which forms it can be prepared in the laboratory. Precipitated chalk is a well-known form of calcium carbonate, used in the preparation of dentifrices and pig- ments. Plaster of Paris is calcium sulphate which has been deprived of part of the water with which it combines, by heat, and its constitution is expressed by the formula (CaSO 4 ) 2 ,H 2 O. It has a great affinity for recombining with more water, with which it sets into a hard mass, and is largely used for lining walls, moulding and other purposes. On heating gypsum to about 120 C. it loses three-fourths of its water and forms the hemi-hydrate (CaSO 4 JH 2 O), and it is to the reconversion of this, by combination with more water, into the form of the dihydrate that plaster of Paris is said to owe its setting powers. Calcium Carbide (sp. gr. 2-22) When ground lime or chalk is strongly heated with coke in an electric furnace to a temperature of about 3,000 C., calcium carbide (CaC 2 ) is produced, and this product is now made on a large scale for use in the preparation of calcium cyanamide and acetylene gas for lighting and other purposes. (See Acetylene.) 76 CALCIUM AND ITS COMPOUNDS CALCIUM (Continued) Calcium Sulphide (CaS), a combination of calcium with sulphur, exhibits the property of giving out a phosphor- escent light in the dark, and is used in the preparation of luminous paint. It is but slightly soluble in water, and when boiled in water it is decomposed, forming the hydroxide Ca(HO) 2 and the hydrosulphide (Ca(HS) 2 ) a product which is used for unhairisg skins before tanning them. Calcium Chloride (CaCl 2 ) can be obtained in a crystalline form combined with water (CaCl 2 6H 2 O), which melts at 29 C. in its own water, and when heated above 200 C. the whole of the water is dissipated and the anhydrous compound results. This is very hygroscopic, and is often employed for drying gases by passing them over and through a tube packed with it. Calcium chloride is extremely soluble in water, and is produced in large quantities as a by-product in many manufacturing operations. In one commercial form it is prepared as a solid containing from 70 to 75 per cent. Calcium Nitrate (Ca(NO 3 ) 2 .4H 2 O) is a white deliquescent substance, soluble in water, and used in pyrotechnics. Calcium Phosphate (tricalcium phosphate, Ca^PO^) is the most important of the phosphates of calcium, and occurs in the mineral forms of sombrerite and coprolites. When acted upon by sulphuric acid it is decomposed, forming a mixture of another phosphate and calcium sulphate Ca 3 (P0 4 ) 2 + 2H 2 SO 4 = CaH 4 (P0 4 ) 2 + 2CaSO 4 . This mixture is known commercially as superphosphate of lime, and is made from bones, which contain calcium phosphate. (See Phosphorus.) In combination with phosphoric acid and calcium fluoride, calcium is also found in the mineral known as apatite. There are commercial preparations of calcium sulphite (in powder and tablets), ferrocyanide, and the so-called acid phosphate (Ca(H 2 PO 4 ) 2 ), a preparation that is used as a substitute for cream of tartar in making "self-raising flour," and baking and egg powders. Calcium Fluoride (CaF 2 ) is found as fluorspar in crys- talline cubes in Derbyshire and Cumberland, and is used as a flux in the reduction of metals. When heated with strong sulphuric acid, hydrofluoric acid and calcium sul- phate are produced. (See Fluorine.) CALCIUM AND ITS COMPOUNDS 77 CALCIUM (Continued) Bleaching-powder, or so-called chloride of lime, is manu- factured on a large scale by the action of chlorine gas upon moist slaked lime until the product contains about from 35 to 38 per cent, of chlorine, the interaction that takes place being represented by the equation Ca(HO) 2 + C1 2 = CaOCl 2 + H 2 O, although there is always an excess of lime left in the resulting product. When treated with water this substance breaks up into calcium hypochlorite (which has been isolated) and calcium chloride 2CaOCl 2 = CaCl 2 + CaCl 2 O 2 . Bleaching-powder is largely employed in the arts, the goods to be bleached being first of all dipped into a dilute solution of the substance and then passed through a dilute acid solution, chlorine gas being thus liberated within the fibres of the fabrics, which are bleached thereby. Bleaching by chlorine is really a process of oxidation, as the chlorine decomposes water in the act, liberating nascent oxygen ; thus indigo blue is converted by chlorine into an orange-red non -tinctorial principle named isatin. It is also used on a considerable scale as a sanitary reagent. Calcium Cyanamide or Nitro-lime (CaCN 2 ) A substance produced by strongly heating calcium carbide in nitrogen gas, the heat about 800 to 900 C. being produced by an electric current passing through carbon resistances placed in the powdered carbide. The output of this pro- duct in 1917 was 900,000 tons. The product consists of about f cyanamide and contains from 20 to 22 per cent, nitrogen, which is transformed by a series of changes into ammonia when the substance comes into contact with water, thus explaining its value as a fertilizer. When pure it is white and crystalline. Calcium Acetate (Ca(C 2 H ? O 2 ) 2 H 2 O) is a white crystalline body, soluble in water, and is employed in the manufacture of acetone and acetic acid. Calcium Bisulphite (Ca(HSO 3 ) 2 ), which is soluble in water, is prepared in the form of a yellowish liquid, having a strong odour of sulphur dioxide by the action of that gas on calcium hydroxide, being generally sold of 8 B strength. It is largely used in the manufacture of wood pulp ; also as an antichlor, as a preservative, and for bleaching sponges. CA LCIUMCA LI CHE CALCIUM (Continued) Calcium Phosphide See Phosphorus. Calcium Tungstate (CaWO 4 ) is a crystalline substance, insoluble in water, used in making luminous paint. CALCULI (Urinary) Consist of or contain uric acid, ammo- nium and other urates, calcium oxalate, calcium phosphate, the double phosphate of ammonium and magnesium, xanthine and cystine, generally constructed round a nucleus of some foreign substance, such as blood-cor- puscles, etc. CALICHE This impure soda nitre (sodium nitrate) occurs in almost unlimited quantities in South America and more par- ticularly in the district of Atacama in Peru. It is cheaper than potassium nitrate and yields 9 per cent, more nitric acid when employed for the manufacture of sulphuric acid. The following analyses have been published : No. i, White Caliche. No. 2, Brown Caliche. Sodium nitrate ... Per Cent. 70*62 Per Cent. 60-97 iodate I-QO 0'73 chloride ... 22'39 16-85 sulphate... I -80 4'56 Calcium sulphate 0-87 I-3I Magnesium sulphate 0- 5 I 5'88 Insoluble matter ... 0-92 4-06 Water ... 0'99 5*64 lOO'OO 1 00 '00 It is often found covered by deposits of costra, which is a harder saline deposit not without value, and the table on the opposite page gives analyses which have been pub- lished of it, and the soda nitre found beneath it in the basin of the Loa (Chili). Sometimes the soda nitre is found in an almost pure state and it can be made to contain from 95 to 96 per cent, by crushing, dissolving in water, and recrystallizing. Some 3,000,000 tons are extracted annually. Apart from what is CA LICHECA MPHOR 79 CALICHE (Continued) used in the alkali trade, there is a much larger consumption as a fertilizing agent. (See Fertilizer.) Soda Nitre. Costra. M (2) Sodium nitrate 5*'5 49-05 18-60 ,, sulphate ... 8-09 9-02 16-64 chloride ... 22-08 28-95 33-80 Potassium chloride 8'55 4'57 2-44 Magnesium o'43 1-25 1-62 Calcium carbonate 0'12 0-15 0-09 Silica and iron oxide 0-90 2-80 3*oo Sodium iodide traces traces Insoluble matter . . . 6-00 3-18 20-10 CALOMEL See Mercury. CALORIMETER A device for measuring the heat generated by burning bodies or by chemical interactions. CALOKIZING A process for the impregnation of steel, iron, copper, brass, etc., with aluminium, forming a homogeneous alloy to a certain depth, effected by heating in a reducing atmosphere with a mixture containing finely divided alu- minium, thus giving a protection strongly resistant to the oxidizing action of high temperature. CALORY See Heat, p. 244: CAMPHENE (C 10 H 16 ) is a colourless, crystalline terpene of sp. gr. 0-8446 and melting-point 49*5 C., which boils at 157 C. It is soluble in alcohol and ether, is prepared by treating pinene hydrochloride with alcoholic potash, and is used in making camphor substitutes. CAMPHOR (Ci H 16 O) is a well-known natural product of characteristic odour formed in camphor- trees (Laiwus camphora) which grow in China, Formosa, and Japan, and is obtained by distillation of the wood and all parts of the trees. The total output of camphor from Japan and Formosa for the year ended March 31, 1918, was 4,854,000 kilos, or approximately 4,777 tons. It is accompanied by oil of camphor, a hydrocarbon allied in composition with turpentine. Camphor is soluble in 8o CAMPHOR CAMPHOR OIL CAMPHOE (Continued) alcohol and ether, crystallizes in glistening prisms, has a sp. gr. of 0-986 to 0-996, melts at 175 C., and can be readily sublimed. By reduction it yields cymene (C 10 H 14 ), and by oxidation with nitric acid it yields camphoric acid (C 10 H 16 O 4 ). Considerable quantities of camphor are made synthetically from pinene (C 10 H 16 ) (the chief constituent of German and American turpentine). Pinene is first of all converted into solid hydrochloride, a white crystalline sub- stance having itself a camphor-like odour, and this is changed into camphene by ammonia, pyridine, or any one of a number of available methods for removing the HC1 constituent. The camphene thus prepared (also a solid body) is next hydrated with borneol (C 10 H 17 .OH) by heating glacial acetic acid and about 2 per cent, of sulphuric acid, and the borneol is finally transformed into artificial camphor by oxidation with air, oxygen, ozone, or other agent, or by dehydrogenation brought about by passing the vapour of the borneol over finely divided copper heated to from 300 to 330 C., thus splitting it up into hydrogen and camphor. Camphor is largely used in the arts and industries, also as a vermifuge and in medicine. The only observable difference between the natural and the artificial camphor is that the former rotates the polarized light ray while the latter is optically inactive. CAMPHORIC ACID (C 10 H 16 O 4 ) is prepared by the oxidation of camphor (C 10 H 16 O) with strong nitric acid and is a white crystalline body, which melts at 208 C., is slightly soluble in cold, but fairly so in hot water, and easily dis- solved by alcohol. It somewhat resembles phthalic acid, and some six modifications of it are known viz., four opti- cally active and two optically inactive forms. It is stated to be used in making celluloid articles. (See Racemic.) CAMPHOR OIL is a by-product obtained in the fractional dis- tillation of crude camphor oil from Cinnamomum camphora, and is a mixture of pinene, cineol, and phellandrene con- taining some camphor in solution. It has a sp. gr. of about 0-87 to i -oo, is soluble in alcohol and ether, and is used as a substitute for turpentine and for illumination. Camphor Wood Oil is sometimes supplied in the form of a yellow crystalline mass, soluble in alcohol and ether, but otherwise as a liquid, and is furnished by dry distillation of the camphor-tree wood (Dryobalanops aromatica). It is used in perfumery. CAMPHOR OILCAOUTCHOUC 81 CAMPHOR OIL (Continued) From a recently published paper it is gleaned that the oil distilled from the leaves of Indian-grown trees contains pinene, dipentene, cineol, terpineol, and caryophyllene, but cineol is stated to be absent from the oil distilled from the twigs. The wood oil is stated to be similar to that produced elsewhere : it contains safrol, eugenol, carvocrol, and other substances, but not cineol. Camphor oil is used in Japan as raw material for the manufacture of heliotropin from the safrol contained in it. CANADA BALSAM See Balsams. CANANGA OIL See Hang Hang Oil. CANAUBA WAX See Waxes. CANDALETTA WAX See Waxes. CANDLES are made of solid fatty acids, with or without admixture of waxes such as paraffin wax or ozokerite. The addition of wax gives hardness to the candles. (See also Fats.) CANDLE-NUT OIL (Lumbang oil) Made in the Philippine Islands from the fruits of the candleberry tree (Aleuritis moluccana). The kernels yield an oil making up 637 per cent, of their weight. It is liquid at 18 C., of pale yellow colour, has a sp. gr. of 0-925, saponification value of 190 to 195, iodine value 136 to 140, and is used as an illuminant and in soap-making, but is not edible on account of its purgative properties. CANNABIS INDICA (Indian hemp) From the flowering tops of Cannabis sativa. CANNABIS SATIVA Common hemp. CANTHARIDES or SPANISH FLIES (Lytta vesicatoria) Coleopterous insects used in medicine for vesicating pur- poses in the form of tinctures and plasters, also for com- pounding hair tonics. The active principle is a poisonous crystalline substance named cantharidin (C^H^O^ which is prepared from these insects or from Mylabns cichoni by digestion with ether or alcohol, or a mixture of these two solvents. CAOUTCHOUC See Rubber. 82 CAPILLARY ATTRACTION CARBAMINES CAPILLARY ATTRACTION results from the adhesion or cohesion of fluids to solids as instanced by a burning night- light in which the melted wax flows to the burning wick. Water is supplied to the roots and stems of growing plants by capillary attraction. CAPRIC ACID (C 10 H 20 O 2 ) A member of the normal fatty acids, present in cow's and goat's milk and cocoa-nut oil, and can be formed by the oxidation of oleic acid. It melts at 31 C., and is soluble in alcohol. CAPROIC ACID (CgH 12 O 2 ) A member of the normal fatty acids, contained in goat's milk and cocoa-nut oil, and often forms one of the products of the oxidation of higher acids of the same series. It is an oily body of sp. gr. 0-931 at 15 C., with a sudorific odour, and is soluble in alcohol and ether. CAPRYLIC ACID (C 8 H 16 O 2 ) A fatty acid of unpleasant odour contained in cow's milk, cocoa-nut oil, Lemberg cheese, and some fusel-oils. It has a sp. gr. of 0-9185, melts at 1 6 C., and is soluble in water, alcohol, and ether. CAPSICUM (Cayenne pepper) Prepared from the dried ripe fruit of Capsicum fastigiatum. Though used as a condiment in the main it is also employed medicinally as a counter-agent to the relaxing effects of heat and also to check the drink-craving of dipsomaniacs. The pungent principle of Spanish pepper (the fruit of Capsicum annuum) is said to be an alkaloid named capsaicin (C 18 H 29 O 3 .N). The name " capsicine " has been applied in America to an oleo- resinous extract from Capsicum baccatum. CARAGHEEN MOSS An Irish moss or alga used as a food. CARAMEL A dark-coloured substance, soluble in water, made from cane-sugar by heating it above its melting-point (160 C.) up to about 170 to 180 C., when it loses two molecules of water and caramelan (C 12 H 18 O 9 ) is formed a brown colouring matter which is the characteristic principle of caramel or sugar dye. CARAWAY The dried seeds of Carum carvi yields a thin, nearly colourless oil (soluble in alcohol and ether), contain- ing carvone and dextro-limonene. Sp. gr., 0-907 to 0-915 ; optical rotation, +75 to +85; refractive index, 1-4867 to 1-4970. It is used in medicine and in flavouring. CARBAMIDE See Urea. CARBAMINES Basic isocyanides, such as methyl isocyanide (CH 3 NC). CA RBA ZOLECA RBOHYDRA TES 83 CARBAZOLE (C 12 H 9 N or (C 6 H 4 ) 2 NH), the imide of di- phenyl, is a constituent of coal-tar and crude anthracene. It is a white, crystalline substance which melts at 238 C., is readily sublimable, and can be formed by passing the vapour of diphenylamine through red-hot tubes. A recently patented process for its manufacture consists in heating the crude article with an alkali metal or hydroxide in the presence of an indifferent solvent, such as naphthalene or toluol, under pressure, and at a temperature below the melting-point of the alkaline carbonate. The solvent is subsequently removed, and the alkali-carbazole decomposed by boiling with water. Carbazole is soluble in alcohol and ether, but insoluble in water, and is used in the manufacture of dyestuffs. (See Imides.) CARBIDES Compounds of carbon with metals such as calcium carbide and cast-iron, a quality of which can be made corresponding with the formula CFe 2 . CARBOHYDRATES constitute a large body of organic com- pounds built up for the most part of carbon with hydrogen and oxygen in the proportion in which they exist in water hence the name. They include sugars, starches, and cellu- loses, but there are other carbohydrates such as rhamnose (C 6 H 12 O 5 ), in which the hydrogen and oxygen constituents are nol present in the water proportions. According to one grouping now observed, they are divided into three great classes viz., the Monosaccharoses, including arabinose (C 5 H 10 O 5 ), and glucose and fructose, which are isomeric bodies (C 6 H 12 O 6 ) ; the Bi and Trisac- charoses, which may be viewed as anhydrides of the first group (that is, devoided of i or 2 molecules of water re- spectively), such as cane-sugar (CjnHaaO^, which must then be regarded as the anhydride of glucose ; and the Poly- saccharoses or polyoses, including the starches and the celluloses, from which a monosaccharose can be obtained by hydrolysis. The compounds of the first class are sweet, are all soluble in water and do not crystallize, at any rate not very well ; those of the second class are also sweet, and crystal- lize ; whilst the members of the third class are not sweet, are not soluble in water, and are non-crystalline. The simple sugars combining the chemical properties of alcohols and aldehydes are now termed aldhoses, while those which are at the same time like alcohols and ketones are styled ketoses. 84 CA RBOHYDRA TESCA RBON CARBOHYDRATES (Continued) Many of these substances are described under their several names. As a class, the carbohydrates char when heated strongly, and give off an odour of burnt sugar. (See also Saccharoses, Starches, and Sugar.) CARBOLIC ACID Liquid commercial carbolic acid is a straw-coloured liquid of about ro8 sp. gr., and is a mixture of phenol (C 6 H 5 OH) and cresol (C 7 H 7 OH) with some other associated substances, all of which are termed " tar acids." It is separated from the cruder coal-tar distillates from which it is prepared, by extraction with caustic soda, the saponi- fied liquid thus obtained being afterwards treated with sul- phuric acid, which combines with the soda and sets free the " tar acids." (See Phenols.) CARBON AND ORGANIC MATTERS Carbon (C) atomic weight, 12; melting-point, above 3,600 C. is well known in the three forms of the diamond, graphite (plumbago), and charcoal. It is also found widely distributed in nature, not only as a constituent of animal and vegetable tissues, and in the air in the form of carbon dioxide (CO 2 ), but also in combination as calcium carbonate (CaCO 3 ) in the rocks known as limestone and dolomite. Diamonds are found in many deposits in Brazil, India, South Africa, and elsewhere, and are for the most part colourless, but sometimes tinged with various colourings. Minute diamonds have been made artificially on a very small scale, and proved to have the same composition as the natural diamonds. When strongly ignited, diamonds burn up in the presence of oxygen into carbon dioxide (CO 2 ), just as charcoal does at a lower temperature, thus proving them to consist of carbon. Graphite is found plentifully in nature in Canada, Japan, Siberia, Spain, California, Ceylon, and elsewhere, including Borrowdale in Cumberland, where it is used in the pre- paration of pencils. It is a shiny, soft, nearly black sub- stance consisting mainly of carbon, and on account of its refractory character it is used for the manufacture of so- called plumbago crucibles that is, crucibles made of fireclay mixed with graphite and arc-light carbons. It is also employed as a polish and coating (blackleading) for iron articles to prevent rusting, and as a paint pigment. Carbon ic also known in impure form as coke, lamp- black, and animal charcoal (bone-black), and this last- named substance is used in refining sugar, glycerine, fats, CARBON AND ORGANIC MATTERS 85 CARBON AND ORGANIC MATTERS (Continued) etc., to decolorize the solutions, having the property of taking up many kinds of colouring matters. In this property, birch charcoal-dust is stated to be equally efficient. Animal charcoal prepared from bones contains about 81 per cent, of calcium and magnesium phosphates and calcium fluoride, from 7 to 8 per cent, of calcium carbonate and other salts, and from 10 to n per cent, of carbon. Most of the carbon black used in the United States of America in the preparation of inks, polishes, pigments, and the rubber industries, is now made by the incomplete com- bustion of natural gas in air. It is of a velvety black character, but only a small percentage of the total carbon is recovered (by collection upon a metallic surface held in contact with the flame) namely, from ij to 3^ per cent. Charcoal has the property of absorbing gases very readily, wood and peat charcoal being superior in this respect to animal charcoal. The absorptive power of wood char- coal is notably increased by prolonged heating, and the denser charcoals notably those from palm-nut, cocoa-nut, and fruit stones are the most efficient gas absorbents. The following table shows the capacity of absorption of various gases by boxwood charcoal : Ammonia gas ... ... ... 90 volumes Hydrochloric acid gas 85 Sulphur dioxide gas 65 Hydrogen sulphide gas 55 Carbon dioxide gas 35 Oxygen gas 9-25 (See Adsorption.) Water is not adsorbed by charcoal, but absorbed or held by capillary action, and the adsorptive power of charcoal varies with the method of its preparation within very wide limits. The adsorption of oxygen by charcoal is considered due to a surface action, the product being a kind of carbon oxide which upon heating, breaks up into carbon monoxide and carbon dioxide, so that it has to be regarded as an intermediate compound in the combustion of the charcoal. "Char" does not only adsorb colour from complex solutions, but will retain sometimes with great avidity many mineral and organic compounds, such as the alkaloids, for which, indeed, purified animal black is an antidote. All vegetable matters consist, in part, of carbon in chemical combination with hydrogen and oxygen, and when they are burned with an insufficient quantity of air or oxygen, a 86 CARBON AND ORGANIC MATTERS CARBON AND ORGANIC MATTERS (Continued) mass of " char," or carbon, remains behind. For example, when wood is burned in a smothered sort of way that is, with an insufficient quantity of air or oxygen a part of it is left behind in the form of wood-charcoal ; in fact, that is how charcoal is prepared. Of course, if enough oxygen or air is supplied to burning wood or coal, all the carbon becomes consumed by entering into combination with the oxygen, and only the ash is left. This ash consists of mineral matters which were present in the wood and coal before burning. Vegetable Matters There are an immense number of vegetable substances and products, such as sugar, rosin, starch, gum, linseed oil, castor oil, cocoa-nut oil, various fats, essential oils, and colouring matters, all of which consist of chemical compounds of carbon with hydro- gen and (mostly) oxygen. All these products of vegetable life are built up by chemical processes which take place in their living organisms, and are derived from the carbon dioxide absorbed from the soil and air by their roots and other parts stomata, or small openings on the lower surface of leaves and this fact demonstrates very forcibly the im- portance of that substance as a constituent of the atmo- sphere. Many of these products can be built up artificially by means of synthetical processes, showing that these natural processes are essentially of the same order as other chemical processes, although very complicated and at present imperfectly understood. Amongst the substances that have been produced by chemists may be mentioned formaldehyde, urea, alcohol, glycerine, tartaric acid, indigo- tine, vanillin, alizarin, indiarubber, and coumarin (the odoriferous principle of the Tonka bean) ; also many synthetical perfumes, the manufacture of which has become an important industry. We may well be excited to wonder by the marvellous extent and nature of the structures (forms), the tissues, the colouring matters and the products that characterize vege- table life, all of which are built up out of the constituents of the soil and the air by the living agencies contained in their seeds. These wonderful processes of nature may be compared with the determining force that causes many salts in a state of solution to crystallize out therefrom in such beautiful geometrical or symmetrical forms as referred to in another section. Animal Matters Other organic compounds are found to exist in all parts of the flesh, the brains and other parts CARBON COMPOUNDS 87 CARBON AND ORGANIC MATTERS (Continued) of animals, but sometimes phosphorus is also found in association, and these organic compounds are even more complex. By animals we mean not only human beings, but all beasts, birds, fishes, and insects. Compounds, of which carbon forms an important constituent, are generally termed organic, and all of them are combustible that is to say, they can be burned up if heated sufficiently in the presence of plenty of air or oxygen. CARBON COMPOUNDS Carbon forms two compounds with oxygen viz., carbon monoxide (CO) and carbon dioxide (CO 2 ). The former is produced whenever carbon is burned with an insufficient supply of oxygen to convert it into the dioxide, and may be prepared in the laboratory by passing a stream of the carbon dioxide gas over charcoal heated to redness: CO 2 + C = 2CO. It is a colourless gas of poisonous properties, but slightly soluble in water, i volume of which at o C. dissolves 0-0328 volume of the gas, and it is utilized in a process for the manufacture of the metal nickel. (See Nickel.) It occurs at times in coal- mines, and is known as white-damp. (See Safety Lamp.) Carbon dioxide is elsewhere referred to as a constant constituent of the atmosphere and as a product of respira- tion. It is the gaseous product which is obtained whenever carbon is burned with a sufficiency of oxygen, and, like carbon monoxide, is a colourless gas which admits of con- densation into the liquid and solid forms. It can readily be produced by the action of acids upon carbonates, such as calcium carbonate (chalk and marble), and when hydro- chloric acid is used in this process the change that takes place is represented as follows : CaCO 3 + 2HC1 = CaCl 2 + H 2 O + CO 2 that is to say, the carbon dioxide gas escapes in a brisk effervescence, calcium chloride being left behind in solution. One volume of water at o C. dissolves 1713 volume of the gas, which is employed commercially in various ways, both as a gas and in liquefied form ; amongst other applica- tions for impregnating water under pressure (making what is called soda-water), as a fire extinguisher and for re- frigeration. It is one of the constituents of what is called black-damp or choke-damp by coal-miners, and often occasions loss of life in mines after explosions. Carbonic Acid (H 2 CO 3 ) This combination of carbon di- Qxide with water (CO 2 + H 2 O = H ? CO 3 ) although itself an t 88 CARBON COMPOUNDS CARBON COMPOUNDS (Continued) unstable body forms with bases a great series of well- defined compounds known as carbonates. Thus, by com- bination with the so-called alkalies and alkaline earths, we get the following series : Sodium, potassium, and ammonium carbonates (Na 2 CO 3 , K 2 CO 3 , and (NH 4 ) 2 CO 3 ), all of which are soluble in water and calcium, barium, and magnesium carbonates (CaCO 3 , BaCO 3 , and MgCO 3 ), all of which are insoluble in water or. practically so. Carbon also combines with sulphur to form the evil- smelling compound known as carbon disulphide (CS 2 ), which may be prepared by passing the vapour of sulphur over red-hot carbon, the CS 2 , which is volatile, being sub- sequently condensed in properly cooled vessels. Carbon disulphide is a colourless liquid of sp. gr. i '27 ; it is manufactured on a considerable scale, and employed as a solvent of caoutchouc, fats and other substances, also in processes for extraction of essential oils and perfumes, etc. There are many organic compounds which are composed of carbon and hydrogen only, termed hydrocarbons, in- cluding such substances as methane or marsh-gas (CH 4 ), acetylene (C 2 H 2 ), benzene (C 6 H 6 ), naphthalene (C 10 H 8 ), and turpentine (C 10 H 16 ). Cyanogen (C 2 N 2 ) consists of carbon and nitrogen only. Many others contain oxygen in addition to carbon and hydrogen, and there may be named as examples, alcohol (C 2 H 6 O), glycerine (C 3 H 8 O 3 ), acetic acid (C 2 H 4 O 2 ), phenol (C 6 H C O), and the carbohydrates. Another class consists of carbon, hydrogen, and nitrogen, including prussic or hydrocyanic acid (CHN) and aniline (C 6 H ? N), whilst yet another class contains oxygen in addition to these three elements, such as urea (CH 4 N 2 O), indigotm(C 16 H 10 N 2 O 2 ), morphine (C 17 H 19 NO 3 ),and quinine 2n 2422 . There are still more complicated organic substances in which other elements exist in combination with carbon, and one or more of those already mentioned, such as sul- phur, phosphorus, chlorine, bromine, and iodine. The chief solid parts of the living tissues of animals are composed of so-called albumins or albuminoids containing from 527 to 54-5 per cent, carbon ; 7 to 7*3 per cent. hydrogen; 20-9 to 23-5 per cent, oxygen; 15 to 18 per cent, nitrogen ; and 075 to 5 per cent, sulphur, approxi- mately represented by the formula C 72 H 112 Nj 8 SO 22 . CARBONATES" CARBORAFFIN " 89 CARBONATES See Carbon. CARBON DIOXIDE See Carbon. CARBON DISULPHIDE See Carbon. CARBON ELECTRODES, as used for electric furnace work, are of several kinds, some being made of graphite, others of carbon derived from the baking of coal-tar pitch having a melting-point of from 150 to 200 F. A good pitch of this character loses nearly all its volatile matter at 600 F. Anthracite coal is one of the best materials for the making of amorphous carbon electrodes. The electrodes are formed by ramming the material into the mould, wherein it is calcined. CARBONIFEROUS The oldest or Palaeozoic system of geo- logical formation, including the coal-measures. CARBON MONOXIDE See Carbon. CARBON TETRACHLORIDE (CC1 4 ) A thin, colourless, poisonous liquid, of pungent aromatic odour, which boils at 77 C., prepared from chloroform or from carbon disul- phide by the action of chlorine. It has a sp. gr. of 1-5835, and is largely used as a solvent for fats, in fire extinguishers, and making cleaning compounds. Experience has shown that it is dangerous to use carbon tetrachloride fire ex- tinguishers in confined spaces where users cannot avoid breathing the poisonous fumes that are produced by its decomposition. CARBONYL CHLORIDE (Phosgene) (COC1 2 ) is produced by exposing a mixture of carbon monoxide and chlorine gases to sunlight, and was used for "gassing" in the great war, being a suffocating and extremely poisonous gas. It is best produced by passing a rapid current of the mixed gases, at the ordinary temperature, over highly activated wood charcoal, the product being liquefied by use of a freezing mixture. The liquefied carbonyl chloride has a sp. gr. of i -43 at o C., boils at 8-2 C. (so that it immedi- ately assumes the gaseous form upon exposure to the air), and crystallizes at - 128 C. Petrol, benzol, and ethyl- acetate, dissolve an equal weight of the gas, and these solutions are used in the coal-tar colour industry and for exterminating rats and moles. CARBONYLS See Metallic Carbonyls. " CARBORAFFIN "A carbonaceous decolorant black, made by mixing peat with a strong solution of zinc chloride, drying, and heating to 700 F., the zinc being subsequently washed out with dilute hydrochloric acid and water. 90 CARBORUNDUM CARRAGHEEN CARBORUNDUM (SiC) A greenish, blue-black, crystalline compound of carbon and silicon, largely used by reason of its great hardness, for grinding and cutting metals in engineering shops ; made by heating in the electric furnace a mixture of fine sand and carbon with a little salt. Its sp. gr. is 3-12 to 3-20. CARBOXYLIC GROUP (COO H) Characteristic of the mono- basic fatty acids, the H of which is replaced in the formation of salts. CARBUNCLE Garnet. CARDAMOMS The nearly ripe fruit of shrubs (Elettaria vepens, Alpinia cavdamomum, and Amomum repens) which grow on islands in the Indian Sea, and are used as condiments and valuable stimulant aromatics. They yield an aro- matic essential oil amounting to from 3 to 8 per cent., having a varying sp. gr. of from 0*895 t '947 ' rotation, + 22 to +46; and refractive index of 1*460 to 1*4673, according to the kind, there being several oils on the market, known as Ceylon, Malabar, Siam, etc. Old carda- mom oil has been found to deposit crystals of a terpene hydrate (C 10 H 16 ,3H 2 O). The Ceylon oil is said to contain chiefly terpenes ; the Malabar oil contains cineol as its chief constituent; while the Siam oil contains borneol as chief constituent, and all are used in medicine and for flavouring purposes. CARMINE The colouring matter of cochineal, prepared by treating the watery extract of cochineal with cream of tartar, alum, or acid potassium oxalate. This coagulates the albuminous constituents, and the colouring principle is carried down with the precipitate. It is soluble in water and alcohol. Carminic acid, the active principle, would appear to have the formula C 22 H 24 Oj 2 . It is a crystalline body and gives well-defined salts. (See also Kermes.) CARNALLITE See Potassium. CARNAUBA WAX (Brazil wax) See Waxes. CARNELIANS A species of chalcedony. (See Cornelians.) CARNOTITE A yellow mineral of variable composition con- taining uranium and vanadium with lime and potash, etc. It is radio-active, and a source of radium. CARRAGHEEN (Chondrus crisfus] See Agar-Agar, CA RRON OIL- CA SSA VA 9 1 CARRON OIL A mixture of olive oil and lime-water in equal parts, used as an application for burns. CARROTENE See Chlorophyll. CARTHAMUS See Safflower. CARVENE A terpene (C 10 H 16 ) contained in oil of cumin. CARVONE (Carvol) The principal constituent of oil of cara- way seeds ; a liquid ketonic body (C^H^O), which yields carvacrol (a liquid substance isomeric with thymol) upon heating. Its sp. gr. is 0-9598, and boiling-point 224 C. CASCARA SAG-RADA The dried bark of Rhamnus purshianus, used as a laxative. CASCARILLA BARK is from shrubs (Croton eleutheria and Croton cascavilld) indigenous in the West Indies. In addition to other extractives, it yields under J per cent, of a volatile aromatic oil and a crystalline body named cascarillin. The bark infusion is used medicinally as a stomachic, tonic, and expectorant. CASEIN The nitrogenous constituent of the milk of mam- malia, forming the principal constituent of cheese in which it is admixed with butter. Chemically it is to be regarded as an albuminous body, somewhat allied to legumin or vegetable casein. Associated with the fat of the milk, it separates when the milk is coagulated either by heating with or without the addition of acetic acid, or by means of rennet. Its composition may be expressed percentically as follows : Carbon 53-8 Hydrogen ... ... ... ... j'2 Nitrogen ... ... ... ... 15-6 Oxygen ... ... ... ... 22^5 Sulphur ... ... ... ... 0*9 i oo-o It is white to yellow in colour, and is soluble in alkaline solu- tions, but not in water. Industrially it is prepared by precipitation with sulphuric acid and finds large employ- ment, considerable quantities being also imported, particu- larly from the Argentine Republic. It is used in preparing adhesives, ivory substitutes, paints, etc. CASSAVA A starch obtained from the roots of the manioc (Jatropha manihot L.) which grows in the East Indies, and from which tapioca also is prepared. 92 CASSIA CASTOR OIL CASSIA is the bark of the Chinese Cinnamomum avomaticum. It yields from |- to 2 per cent, of a volatile oil by distillation with salt water, nearly identical with cinnamon oil, and is used for scenting brown Windsor soap, etc. Cassia buds from the Cinnamomum lauresii yield the same oil which, however, is not so aromatically pleasant as cinnamon oil. The sp. gr. of the oil is 1*05 to 1*065, having a rotation of + i to - i, and a refractive index of 1*585 to 1*605. CASSITERITE Another name for tinstone. (See Tin.) CASTANHA OIL (Brazil-nut oil) is expressed from Brazil nuts, has a sp. gr. of 0-918, a saponifkation value of 193^5, and iodine value 106-22. It melts at 0-4 C., is soluble in ether and carbon disulphide, is pale yellow in colour, and is used in soap-making, in perfumery and as a food. CASTILE SOAP is a hard soap made from olive oil, and is used for making pills and plasters. CASTOR OIL is a thick, non-drying, yellowish or pale green, odourless oil, extracted or expressed from the seeds of Riciuus communis, a plant, which is cultivated in the East and West Indies, Java, Mexico, and other warm climates. It is a mixture of several glycerides, and upon saponifica- tion yields a soap which is perfectly dissolved by water. Its chief constituent fatty acid is ricinoleic acid (C 18 H 34 O 3 ), which melts at 4 to 5 C., has a sp. gr. of 0-95, and re- sembles oleic acid in properties. The seeds of the plant yield from 45 to 55 per cent, oil, the medicinal oil being prepared from seeds which have been husked, while the second and third pressings are used industrially. The bleaching of castor oil is usually effected by agitation at 200 F. with 2 to 4 per cent, of Fuller's earth, followed by agitation with from 0-2 to 1-5 per cent, of prepared decolorizing carbon. In addition to triricinolein, it also contains palmitic and oleic acids. The pressed cake is unfitted for cattle food, as it contains an alkaloid named " ricine," derived from the husks of the seeds. Castor oil has a sp. gr. of 0-969, a saponification value of 176 to 183, an iodine value of 83 to 86 ; solidifies at - 18 C., and is soluble in alcohol, ether, benzene, etc. The lower qualities are used for soap-making and leather- dressing, as lubricants, in the preparation of Turkey-red oil, and in the manufacture of artificial leather, linoleum, and rubber substitutes. CA TA LA SECA TALYTIC 93 CATALASE A common name for a group of enzymes (one of which can be prepared from germinated beans), which have the power of catalyzing hydrogen peroxide. CATALYTIC The term given to a remarkable property which is exhibited by certain substances in initiating or accelerating and exhilarating chemical action between two or more other chemical substances. For example, platinum in a spongy condition promotes the combination of hydrogen and oxygen gases to form water ; a little of this so-called platinum black, when thrown into a mixture of the two gases, causes them to combine with a loud explosion. It also causes the ignition of coal gas in presence of air, and there is an automatic gas-lighter constructed on this principle. The primary alcohols are resolved into aldehydes and hydrogen by passing their vapours through tubes contain- ing certain metals or their oxides ; for example, ethyl alcohol gives an 80 per cent, yield when passed over zinc at 660 C., and many organic compounds can be reduced by mixing them with hydrogen and passage over platinum black at a moderate temperature. Electrolytic copper does not exercise any catalytic effect on the oxidation of ethyl alcohol, but when prepared by reduction of the oxide it catalyzes the action with the formation of acetaldehyde or acetone. Fuming sulphuric acid is now made by a catalytic pro- cess, and the catalytic hydrogenation of oils may also be cited as affording another illustration of catalytic processes. (See Hydrogenation.) Many finely divided substances are capable of exercising a catalytic effect : pure precipitated silica after moderate calcination effects the decomposition of ethyl alcohol at 280 C., producing ethylene. Pulverized quartz and alumina are also capable of serving as catalysts, and it has been shown that titanium oxide (TiO 2 ) at a temperature of 290 to 300 C. effects the esterification of the vapours ot acids and alcohols. In addition to platinum and copper, iron, nickel, cobalt, palladium, osmium, iridium, ruthenium, and rhodium are all employed as catalysts, and for the reduction of liquid compounds. The catalyst is generally used in suspension, being removed at the completion of the operation by filtration or otherwise. There are substances which act as anti-catalysts, and others as " poisons " to the catalysts, and of course it is important that these should be absent in all such operations. The catalyst is often unimpaired at the end of the action, although its action is probably dependent upon the forma- 94 CATALYTIC CELESTINE CATALYTIC (Continued) tion of intermediate compounds. In some cases it would appear that occlusion or adsorption of one or more of the interacting substances occurs at the surface of the catalyst, thus securing greater concentration. (See also Enzymes.) CATECHOL (Pyrocatechin) (C 6 H 6 O 2 or C 6 H 4 (OH) 2 ) is a so- called dihydric phenol, contained in raw beet sugar and the leaves of the Virginia creeper, and obtainable by chemical processes from guaiacol and some other natural resins. It is a crystalline body which melts at 104 C., is readily soluble in water and alcohol, and can be sublimed. It is antiseptic in character, and used in photography. CATECHU (Cutch) An astringent extract, rich in tannin (25 to 50 per cent.), prepared from the wood and pods of various species of acacia and other catechu plants, grown in Bombay, Bengal, Nubia, and elsewhere, by digest- ing the various parts of the plants in water and evaporation of the solutions. Apart from its use in tanning, it is used in dyeing, as when treated with nitric acid it yields a bright yellow powder possessing dyeing characters like those of picric acid. Catechu contains a crystalline principle named catechin (C 15 H 14 O 6 4H 2 O) readily soluble in hot water and in alcohol. There are a number of varieties including gambia catechu (Catechu pallidum)j a pale sort ; betel-nut catechu ; cutch (Areca catechu) ; and Nubian catechu from Egyptian acacias. CATHARTIN The purgative constituent of senna. CATHODE RAYS See Radio-activity. CAT'S EYE A quartz of translucent appearance found in Ceylon. CAUSTIC SODA See Sodium. CEDAR-WOOD OIL A pale yellow essential oil of agreeable odour, used in perfumery and as an insectifuge, obtained from the wood of thejuniperus virginiana, etc., to the extent of about 1 6 ozs. per cwt. Sp. gr. about 0-940 to 0-960; optical rotation, -25 to -38; refractive index, 1*498 to 1-504. It is soluble in alcohol and ether, and contains a crystalline substance named cedar-camphor (cedrene). CELERY OIL Distilled from the fruit of Apium graveolens, having a sp. gr. of from 0-87 to 0*895. ^ nas * ne odour and taste of celery, contains limonene associated with a number of other substances, and is used for flavouring purposes. CELESTINE (Celestite) Native strontium sulphate (SrSO 4 ). CELL U LOW CEMENT 95 CELLULOID (Xylonite) In the preparation of this material, cellulose (usually in the form of paper) is nitrated with a mixture of sulphuric and nitric acids until the nitrogen content amounts to about 10 to n per cent., and after bleaching, washing, and drying, it is gelatinized with a mixture of camphor dissolved in alcohol into a jelly, at which stage any colouring matters may be introduced as desired. It is then manipulated on hot rollers, and pressed into blocks or other forms. It is a plastic material at 75 C, and after evaporation of the solvent and upon cooling can be turned on a lathe. It is largely used for making combs, brush and knife handles, piano-keys, billiard balls, collars, cycle pumps, mudguards, etc. The celluloid used in making cinematograph films is of a more highly nitrated character, while the proportion of camphor incorporated is smaller, but it is much more inflammable in character. (See Explosives.) CELLULOSE (C 6 H 10 O 5 ) X The structural and preponderating tissue forming the walls or skeletons of plants, convertible into sugar, gun-cotton, nitro-cellulose, collodion, artificial silk, etc., and extensively employed in the manufacture of paper and compounding celluloid articles and the prepara- tion of celluloid films, some of which have a basis of cellu- lose acetate dissolved in acetone or cellulose dissolved in amyl acetate or amyl alcohol. (See Pyroxylin.) Cotton contains about 90 per cent, cellulose, and the pro- portion in woods of various sorts ranges from about 40 to 60 per cent. (See Paper.) Cellulose is soluble in an ammoniacal solution of cupric oxide, and this solution readily dissolves cotton and linen fibres. Advantage is taken of this solubility in the manu- facture of " Willesden paper." There is now a large industry also in the manufacture of artificial silk made from cellulose. Celluloses used for industrial purposes are of three classes viz., the so-called pecto-celluloses such as cotton, ramie, flax, and hemp ; the ligno-celluloses such as jute and the various woods ; and, lastly, cereal straws and grasses. Ramie and hemp contain about from 63 to 66 per cent, cellulose. (For note concerning the constitution of cellulose see Glucose ; see also Silk Artificial, and Paper.) CEMENT (Portland cement) is prepared from a mixture of clay and chalk (containing about 76 per cent, of the latter), which are ground together in water, and after allowing the mixture to settle, the water is poured off and the deposit is 96 CEMENT CERIUM CEMENT (Continued) calcined (intensely heated). It is then ground dry ready for use. It has a sp. gr. of 3*17, and on the average it con- tains about 22 per cent, silica (SiO 2 ), 62 per cent, lime (CaO), and 7-5 per cent, alumina (A1 2 O 3 ). When mixed with a small proportion of water, it forms a very hard and tenacious cement which expands as it solidifies or " sets," and unlike ordinary mortar can be used for hydraulic purposes. Storage of cement prolongs the time of initial and final setting. Cement consists mainly of lime and silica combined with a certain amount of alumina and small amounts of potash, soda, and magnesia in the form of free salts. The use of blast-furnace slag in the manufacture of cement is now largely practised in the North of England and Scot- land, where suitable clays or marls are rare. The lime which is set free during the setting of Portland cement, like the slaked lime of ordinary mortar, is capable of entering into combination with silica when presented to it in a sufficiently active form, and good cement can there- fore be improved by the addition of a suitable pozzolanic substance. (See Concrete, and for other kinds of cement see Sealing Wax.) CENTRIFUGES (Hydro-extractors) Machines for extracting liquids from solids, for precipitating fine solids from liquids, and for separating liquids of varying specific gravities by - centrifugal action. In the separation of liquids from solids by rotation of the mixture in a cage or drum, the liquid is expelled through openings therein. CERAMIC Pertaining to pottery. CERESINE See Waxes. CERITE A rare mineral, being a hydrated silicate of cerium, containing also lanthanum and didymium, from which cerium is extracted. CERIUM (Ce) and its compounds Atomic weight, 140 ; sp. gr., 7 ; melting-point about 623 C. A rare element found in association with lanthanum in the Swedish minerals cerite, allanite, and orthite, also in gadolinite, wohlerite, and monazite. It resembles iron in appearance, oxidizes quickly in moist air, forms alloys with iron, aluminium, zinc and magnesium, and combines with boron and silicon. It is malleable and ductile. There are two oxides, Ce 2 O 3 and CeO 2 , the latter of which (ceria) is used in the preparation of mantles for use in incandescent gas lighting. CER1 UMCHEDDIT& 9? CERIUM (Continued) The oxalate (Ce 2 (C 2 O 4 ) 3 9H 2 O) and the insoluble fluoride (CeF 4 .H 2 O) (by-products in the manufacture of thorium from monazite sand) were both used during the war in connection with searchlights and tracer bullets. The oxalate is but slightly soluble in water, and in addition to its other uses is employed medicinally for the prevention of chronic vomiting. (See also Pyrophoric Alloys.) CEROTIC ACID (C 26 H 52 O 2 ) A crystalline fatty acid of the normal series and the chief constituent of beeswax, being contained in combination as cerylic cerotate (C 25 H 51 .CO. OC 26 H 5? ) in Chinese wax. It melts at 78 C. and is soluble in hot alcohol. It can be obtained from Chinese wax by melting that substance with potash or by its dry distillation, and from paraffin wax by oxidation with chromic acid. CEROTIN Chinese wax. CERUSSITE (White-lead ore) A mineral lead carbonate (PbCO 3 ) of importance as an ore of lead, found in Corn- wall, Cumberland, Scotland, Mexico, and some of the United States. CETIN The wax-like constituent of spermaceti. (See Waxes.) CHALCANTHITE Native copper sulphate (CuSO 4 ,5H 2 O) found in some Chilian mines, Arizona, and elsewhere. CHALCEDONY A variety of quartz. (See Silicon and Cornelians.) CHALCOCITE (Copper glance) A natural copper sulphide. CHALK Native calcium carbonate of an earthy character, used to some extent as a dressing for heavy lands, also for building purposes and in making cement. CHALYBEATE WATERS These include those found and used as medicines at Tunbridge Wells, Cheltenham, Harrogate, Leamington, Scarborough, Strathpeffer, and elsewhere. They contain iron as ferrous carbonate in a state of solution and constitute valuable tonics in cases of debility. CHARCOAL See Carbon. CHAULMOOGRA OIL A thick, yellowish oil or soft fat, of acrid taste, expressed from the seeds of Taraktogenos Kurzii; of sp. gr. 0-94 and iodine value 96 to 104. Used in medicine. It is soluble in alcohol, ether, etc. The seeds, which are imported from India, yield about 33 per cent, of the oil. CHEDDITE See Explosives, 7 98 CHEESE CHEMICAL CHANGES CHEESE is made from milk by coagulation with rennet and represents its casein constituent with some of its butter. It undergoes certain chemical changes upon keeping, which are not well understood, and is a valuable food containing a considerable amount of nitrogen. It varies in composition according to the milk from which it is made and to details in the process of manufacture. It contains from 30 to 60 per cent, water, 2| to 5^ per cent, nitrogen, from 19 to 33 per cent, fat, and from 4^ to 7 per cent, mineral sub- stances (ash). Roquefort cheese is made from a mixture of sheep's and goat's milk, and Gruyere cheese was originally made exclusively from goat's milk, but is now made from cow's milk. CHEMICAL ATTRACTION or affinity (the force or power which brings about chemical combination and keeps the resulting compounds comparatively intact as entities) is correlated to other forms of force, such as heat, light, electricity, mag- netism, and gravitation, and all chemical changes involve the consumption or expenditure of energy to bring them about, many being attended with the production of heat, light or electricity. CHEMICAL CHANGES All articles of food and clothing, the materials of which our houses and buildings are constructed and which are needed for their decoration or repair, every art and every industry all depend essentially for their production or activity upon chemical changes as realized in nature or made by man to serve human purposes. The same is true of the production and decay of animal and vegetable matters, as also the processes by which they are broken up and the resulting products made available in their turn as food for new life : the very diseases of man- kind and animals, as also their treatment, are all chemical in essence and involve chemical changes. These chemical changes constitute a sort of adaptation of matter to environ- ment, and in a sense are acts of creation, as every such change produces products which, although related, are quite distinct in character and properties from the original substances which give rise to them when subjected to the required influences. Thus, in a very literal sense, all matter which, as will be seen in other places, appears to be essen- tially one in nature is actuated by a spirit of life, being susceptible to change when the environment is appro- priate. In other words, the liability to change is equivalent to life. All such changes are necessarily accompanied by a relationed redistribution of energy. (See Atoms, Ele- ments, and Radio-activity.) CHEMICAL COMPOUNDS 99 CHEMICAL COMPOUNDS There is a fundamental differ- ence between a mere mixture and a chemical compound. If some lead shots be mixed with some powdered sulphur ever so carefully, they can be easily separated again. For instance, the sulphur can be blown away from the mixture by the use of a bellows, or all the shots can be picked out and removed one by one. But if, instead of removing the shots, the mixture is subjected to strong heat, both the lead and the sulphur disappear as such. They enter into combination with each other in a chemical sense, and a new substance or chemical compound is formed, named lead sulphide, which has properties or qualities quite different from those of its constituents. The tarnish which forms on articles of silver when exposed to the air of towns is also a chemical combination of silver and sulphur (silver sulphide) due to the presence of traces of a compound of sulphur in the air. Iron filings may be mixed ever so carefully with sand ; but this, again, is a mere mixture, and all the iron filings may be separated or withdrawn from the mixture by means of a magnet, which attracts the iron and not the sand, showing that they are not in chemical combination, but only mechanically admixed. Gunpowder is only a mechanical admixture of nitre, charcoal, and sulphur, and their separate respective particles can be seen lying apart from each other by means of the microscope. As a further instance of the difference between a mere mixture and a chemical compound it may be mentioned that when quicksilver (mercury) is heated and exposed to the air, it becomes changed into a yellow powder (an oxide of mercury), which is a chemical compound of the mercury and atmospheric oxygen, and by no mere mechanical process can the mercury and the oxygen of which it is compounded be separated from each other, showing that it is not a mere mixture of the two things. Chemical combination always takes place in equivalent weights, or so-called combining proportions of the elements concerned, and the combining weights are the smallest which will combine with one part of hydrogen. Lead, for example, has an atomic weight of 207, so that when it enters into chemical combination with sulphur, which has an atomic weight of 32, 207 parts by weight of lead combine with 32 parts by weight of sulphur, and yield 239 parts of the chemical compound sulphide of lead. Salt (sodium chloride) is a chemical combination of ioo CHEMICAL COMPOUNDS CHEMICAL COMPOUNDS (Continued) 23 parts by weight of the metal sodium and 35^ parts by weight of the gas chlorine, or, in other words, a combina- tion of one atom of each of these two elements. The two atoms thus combined make up a molecule, so that the molecular weight of the compound (salt) is that of the two added together namely, 58^. When salt is decomposed that is, split up by chemical means into its two constituent elements 58^ parts by weight always yield 23 parts by weight of sodium and 35 J parts by weight of chlorine. Most of the oxides, hydrates and carbonates of the metals behave as bases, and in common with the alkalies combine with acids to form salts. When an acid solution is mixed with its equivalent quantity of an alkaline or other basic solution, the acid character of the one solution, and the alkaline or basic character of the other solution, are severally destroyed or neutralized. For example, if a solution of sodium hydrate in water be mixed with one of hydrochloric acid, a chemical interaction takes place, and a salt known as sodium chloride (common salt) is produced in solution. This is represented by formula or equation as follows : NaHO + HCl=NaCl + H 2 0, and if the neutral solution which results from this reaction be heated so as to cause evaporation of sufficient of the water, the salt will be obtained upon cooling of the solu- tion, in a crystalline condition. Lime (calcium oxide, CaO) is an example of another class of bases, which includes baryta or barium oxide (BaO), magnesia or magnesium oxide (MgO), and strontia or strontium oxide (SrO). When lime is added to hydro- chloric, nitric, or sulphuric acid, it enters into combination and forms either calcium chloride, nitrate, or sulphate, as the case may be. Thus, if hydrochloric acid be employed, the change is expressed as follows : CaO + 2HC1 = CaCl 2 + H 2 O, with nitric acid as follows : and with sulphuric acid as follows : CaO + H 2 S0 4 = CaS0 4 + H 2 O. CHEMICAL Cf)MPpUN&ff>*'. --, :- . 101 CHEMICAL COMPOUNDS (Continued) The chloride and nitrate of calcium are both soluble in water, but the sulphate is almost insoluble. Oxides, Chlorides, Bromides, Iodides, and Other Compounds. It has already been stated that combinations or compounds of metals and other bases with oxygen are called oxides, and as further instances, mention may be made of the oxides of zinc, lead, and copper, which are represented by the chemical formulae ZnO, PbO, and CuO respectively. If in place of oxygen the elements chlorine, bromine, iodine, fluorine, and sulphur be severally taken and made to combine with metals or other bases, the resulting compounds are chlorides, bromides, iodides, fluorides, and sulphides. This is shown in tabulated form as below : Compounds of Called- Example. Formula. Oxygen Oxides Zinc oxide ZnO Chlorine Chlorides Sodium chloride NaCl Bromine Bromides Potassium bromide KBr Iodine Iodides Potassium iodide KI Fluorine Fluorides Calcium CaF 2 Sulphur Sulphides Lead sulphide PbS The names used to identify chemical substances are designed as far as possible to indicate their composition, but the system is by no means perfect, and apart from other variations, many old common or familiar names are still retained and used in many books. It frequently happens that the same two chemical ele- ments combine together in various proportions, so forming as many different compounds, and to distinguish these, terminal letters or prefixes are employed. For instance, the two compounds water and hydrogen dioxide (H 2 O and H 2 O 2 respectively) are both composed of hydrogen and water, so the one with the higher proportion of oxygen is styled dioxide or peroxide, water being oxide or hydrogen monoxide. Again, phosphorus combines with chlorine to form two chlorides, PC1 3 and PC1 5 , and these are termed respectively phosphorous chloride and phosphonc chloride, or prefer- ably, phosphorus tfn'chloride and phosphorus pentachloride respectively. 102 a Q&EMFCAL COMPOUNDS CHEMICAL COMPOUNDS (Continued) Acids are eommonly called by their familiar names, but may be, and often are, described as compounds of hydrogen for instance : Hydrochloric acid = Hydrogen chloride. Nitric acid = Hydrogen nitrate. Sulphuric acid = Hydrogen sulphate. The terminals ic and ous are used to denote acids with the greater or smaller proportion of oxygen, where that element enters into their combinations ; thus we get : Sulphuric acid, formed from sulphur tfn'oxide and water, S0 3 +H 2 = H 2 S0 4 . Sulphurous acid, formed from sulphur ^'oxide and water, S0 2 + H 2 O=H 2 S0 3 . Nitn'c acid, formed from nitrogen pentoxide and water, N 2 5 + H 2 0=2HN0 3 . Nitnws acid, formed from nitrogen trioxide and water, N 2 3 + H 2 O=2HN0 2 . When these acids combine with bases for example, potassium oxide they form respectively sulphate, sulphate, nitrate, and nitrate of potassium ; or, instead of expressing them as named, they may be described as potassium sul- phate, sulphite, nitrate and nitrite respectively. The table on p. 103 shows which of the various compounds of the better-known elements are soluble or insoluble in water. It will be observed that some metals, including copper, iron, mercury, and tin, form two compounds of most of the classes, and these are indicated by the termina- tions of the metallic names : thus, ferric chloride is FeCl 3 , and ferrows chloride is FeCl 2 ; mercurii chloride is HgCl 2 ; and mercurows chloride is Hg 2 Cl 2 , and so forth. It will be seen that the names of the compounds containing the larger proportion of metal end with the termination ous ; and those with the smaller proportion, with the ending ic. Carbonates These compounds are described under Carbon. Carbides are combinations of carbon with metals, such as calcium carbide and a form of cast-iron, and these are severally referred to elsewhere. Nitrides are combinations of nitrogen with metals, and are formed by passing ammonia gas over the metals heated CHEMICAL COMPOUNDS 103 CHEMICAL COMPOUNDS (Continued) in porcelain tubes to from 400 to 800 C., the ammonia being thus decomposed into its constituent elements. Hydrides are combinations of hydrogen with metals as, for example, arsenic hydride (AsH 3 ). Phosphides are compounds of phosphorus with metals. (See Phosphorus.) 1 j CO CO 1 1 <5 "rt rf r* T3 fl "ri ^2 s 1 1 1 jl id o E 5 U 52 "3 C/) 5 Al . . I I s s s I NH 4 s s s s s s s Sb I I s I I As . . ss s s I Ba . . s s I s s I I Ca . . ss ss I s s ss ss rn fCupric /u \Cuprous I I I I I s I s s I I Fe f Ferric re \Ferrous I I I I I s s s ss s s I I Pb.. I ss I ss s I I Mg I I I s s s s Mn I I I s s s I TT /Mercuric g \Mercurous I I I I I I s I s s s s I I K .. s s s s s s s Ag . . I I I I s ss I Na . . s s s s s s s f Stannic su \Stannous I I I I I I s s s s s s I I Sr .. ss s I s s I ss Zn . . I I I s s s I S^ soluble, SS = sparingly soluble, I = insoluble in water. Silicon, Boron, and Selenium, in combination with metals form silicides, borides, and selenides, and so far as these substances are of importance, they find description under other headings. Anhydrides as a class are related to the acid-forming oxides, such as sulphur trioxide (SO 3 ), which by combina- tion with water gives sulphuric acid (H 2 SO 4 ) that is, 104 CHEMICAL COMPOUNDS INTERACTIONS CHEMICAL COMPOUNDS (Continued) By abstracting or taking away the water from sulphuric acid it is reduced to its anhydride. The term, however, is used more generally. (See Anhydrides.) Cyanides See Cyanogen. Arsines, Phosphines, and Stibines Three series of very oxidizable compounds formed by replacing hydrogen of arsenic hydride (As 2 H 3 ), hydrogen phosphide (PH 3 ), and antimony hydride (SbH 3 ) by hydrocarbon groups. Hydrosulphides See Sulphur. CHEMICAL CONSTANTS See Constants. CHEMICAL ELEMENTS See Elements. CHEMICAL EQUATIONS See Chemical Interactions. CHEMICAL FORMULAE See Chemical Compounds, Ele- ments, and Formulae. CHEMICAL INTERACTIONS (Reactions and Equations) If some zinc filings be placed in a dilute solution of hydro- chloric acid, a chemical change or interaction is seen to take place, the metal being gradually dissolved, attended with an effervescence due to the formation of hydrogen gas, whilst a solution of zinc chloride is produced as the result of the change. Using symbols, this chemical change is represented as follows : Zn (zinc) + 2HCl (hydrochloric acid) = ZnCl 2 (zinc chloride) -f H 2 ; that is to say, i atom of zinc and 2 molecules of hydro- chloric acid give rise by interaction to i molecule of zinc chloride (which passes into solution) and 2 atoms of hydro- gen gas. Similarly, if some broken pieces of marble (which con- sists of calcium carbonate) be placed in a dilute solution of hydrochloric acid, they dissolve therein, with effervescence, due to the escape of carbon dioxide gas, which results, in consequence of the chemical change that takes place between the marble and the acid. This change is expressed as follows : CaCO 3 (calcium carbonate, or marble) + 2HC1 (hydro- chloric acid) = CaC! 2 (calcium chloride) + H 2 O (water) + CO 2 (carbon dioxide). In other words, i molecule of calcium carbonate and 2 molecules of hydrochloric acid produce i molecule of calcium chloride (which passes into CHEMICAL INTERACTIONS 105 CHEMICAL INTERACTIONS (Continued) solution), i molecule of water, and i molecule of carbon dioxide. The elemental substance called phosphorus (which, in one of its forms, is extensively used in making the com- position used for coating the surface of match-boxes) has a great affinity for that is, a liking or tendency to enter into chemical combination with oxygen, which is one of the constituents of the air, and if a piece of phosphorus be sufficiently warmed (heated to 34 C.) or ignited, and then placed in a glass jar filled with oxygen gas, it combines with it at once, bursts into vivid flame, and after cooling, it is found that on the bottom and sides of the glass jar there is a white deposit resembling snow. This deposit is the product or result of the chemical action, being what is called an oxide of phosphorus having the formula P 2 O 5 . In this chemical change 2 atoms of phosphorus weighing twice 31 = 62 (31 being the atomic weight of P) combine with 5 atoms of oxygen, weighing in all 80 (i 6 being the atomic weight of oxygen), and make 142 parts by weight of the resulting product. Now, as air consists of a mixture of oxygen and nitrogen, if enough phosphorus be employed to use up all the oxygen that is present, only nitrogen is left behind in the gaseous state. Supposing exactly 100 parts of air be used in this experi- ment, 21 parts of the air, consisting of oxygen, enter into chemical combination with the phosphorus, and 79 parts of the air, consisting of nitrogen, are left behind. Heat is often given out as the result of chemical inter- changes, but not always ; sometimes the reverse is ex- perienced, and cold is, so to speak, produced. When charcoal or coke consisting, in the main, of the element carbon is burned in an ordinary fire-grate, the carbon enters into chemical combination with the oxygen present in the air, and produces carbon dioxide. This is represented by symbols in the following equation : C+0 2 = C0 2 . Each atom of carbon chemically combines with 2 atoms of oxygen, and gives rise to the formation of i molecule of carbon dioxide gas. It is to be noted that in this interaction a solid body combines with a gas, whilst the product is entirely gaseous in character, although it can, in point of fact, be converted into the liquid state and even made into a solid form like snow by great cooling under pressure that is to say, by 106 CHEMICAL INTERACTIONS CHEMICAL INTERACTIONS (Continued) squeezing (pumping) a great quantity (volume) of the carbon dioxide gas into a very small space whilst cooling or freezing it at the same time. Mercuric chloride is a combination of mercury with chlorine, and if a strip of copper be placed in a slightly acid solution of that substance, a change takes place, causing the mercury to be deposited, whilst after sufficient time, nothing but chloride of copper is found in solution. In other words, the mercury is replaced (in consequence of the chemical change that takes place) by the copper, and it is found in practice that this exchange takes place in the proportion of 200-6 parts of mercury and 63-5 parts of copper. If this solution of chloride of copper be taken afterwards and exposed, in turn, to the action of a piece of iron, the whole of the copper can be deposited from the solution and replaced by iron ; and now it is found that the metals are again exchanged in their equivalent or atomic weights, 63-5 parts copper being replaced by 56 parts iron. These two changes or interactions are expressed by the two following chemical equations : HgClg (mercuric chloride) + Cu (copper) = CuCl 2 (cupric chloride) + Hg (mercury). CuCl 2 (cupric chloride) + Fe (iron) = FeCl 2 (ferrous chloride) + Cu (copper). Baryta or barium oxide is represented by the formula BaO, but there is another oxide of barium, which chemists call barium dioxide, which has the formula BaO 9 . Similarly, water, which is an oxide of hydrogen, has the formula H 2 O, but there is another oxide of hydrogen which chemists term hydrogen dioxide or peroxide of hydrogen (H 2 O 2 ). Now, when powdered barium dioxide is added to a solution of dilute hydrochloric acid (which has the constitu- tion represented by the formula HC1), the following change takes place : Ba0 2 + 2HC1 = BaCl 2 + H 2 O 2 . This chemical equation represents the fact that i mole- cule of barium dioxide interacting with 2 molecules of hydrochloric acid (hydrogen chloride) produces i molecule of barium chloride and i molecule of hydrogen dioxide, both of which, being soluble in water, remain together in solution. CHEMICAL INTERACTIONS-CHESSYLITE 107 CHEMICAL INTERACTIONS (Continued) It is further evident that the sum of the products is equal to the sum of the substances originally employed, and the equation given above shows that there are employed in this chemical interaction : 1 atom or 137 parts by weight of barium \As contained in i molecule 2 atoms or 32 ,, ,, of oxygen / of barium dioxide. 2 ,, ,, 2 ,, ,, of hydrogen \ As contained in 2 molecules 2 ,, ,, 71 ,, ,, of chlorine / of hydrochloric acid, totalling 7 atoms and 242 parts by weight ; and that there are produced 1 atom or 137 parts by weight of barium \As contained in i molecule 2 atoms or 71 ,, of chlorine / of barium chloride. 2 ,, ,, 2 ,, ,, of hydrogen } As contained in i molecule 2 ,, ,, 32 ,, ,, of oxygen J of hydrogen dioxide, totalling 7 atoms and 242 parts by weight. Incidentally, this equation also affords an illustration of the indestructibility of matter, the forms and combina- tions of which only can be changed. If in the study of any chemical change, the sum of the products found upon analysis is not equal to the parts by weight of the substances employed, it is known to the operator that the analysis is imperfect. CHEMICAL PLANT means the manufacturing apparatus re- quired in respect of the production of chemicals on a large scale, and involves the application of engineering drawings and construction, based upon a knowledge of the properties of the materials to be employed questions of heat-absorp- tion and evolution, its transfer and transmission, and other fundamental principles, including calculations as to the quantities and capacities to be dealt with by the various sections ; in other words, the magnification of those con- ditions ascertained in laboratory practice to realize the best results attainable, having particular regard to the use of materials capable of resisting those forms of chemical attack which may be anticipated. CHEMICAL SYMBOLS See Elements, Chemical Compounds, Chemical Interactions, and Formulae. CHEMISTRY (Definition) The study of the laws of changes of matter. CHENOPODIUM OIL Distilled from the fruit of Chenopodium ambrosioides and used as an anthelmintic, containing an active principle named ascaridole. Sp. gr., about 0-96 to 0-98. CHESS YLITE Native blue oxycarbonate of copper (2CuCO 3 , Cu(OH) 2 ) found at Chessy near Lyons, io8 CHIA OILCHLORANILINES CHI A OIL Expressed from the seeds of the Chia plant (Salvia hispanica), which grows in Mexico, and yields from 24 to 33 per cent., having a sp. gr. 0-9338, iodine value 196-3, and saponification number 192-2. It dries as quickly as linseed oil, is of clear yellow colour, with odour and taste like those of linseed oil, and is said to be largely used as a food and in compounding a particular drink. CHICORY The root of the Chicorium intybus roasted and ground and used to mix with coffee. A strong infusion is said to act as an aperient and sometimes as a diuretic. CHILI NITRE See Caliche. CHILI SALTPETRE See Caliche. CHINA (Porcelain, Pottery, Stoneware, etc.) Articles made from various classes of minerals, such as China clay, a product resulting from the gradual decomposition of rocks (including felspar and granite) in the nature of hydrous aluminium silicates. (See Clay and Porcelain.) CHINESE BLUE A form of Prussian blue. CHINESE INK See Inks. CHINESE WAX See Waxes. CHINESE WOOD OIL-See Tung Oil. CHLORACETIC ACID (CH 2 C1,CO 2 H) A deliquescent crys- talline halogen substitution product of acetic acid, used as a corn and wart remover, and in the synthetic production of indigo. CHLORAL HYDRATE (C 2 H 3 C1 3 O 2 ) A crystalline substance which melts at 57 C., is readily soluble in water and alcohol ; used as a soporific, and having antiseptic proper- ties. By the action of sulphuric acid it is converted into chloral (CC1 3 .CHO), a thin oily liquid of sp. gr. 1-5 12, which boils at 98 C., and becomes reconverted into the hydrate when mixed with a small quantity of water, heat being evolved. Chloral is prepared by the chlorination of alcohol and subsequent distillation. CHLORAMINE-T An antiseptic, being a derivative of toluene, capable of generating chlorine. CHLORANIL (C 6 C1 4 O 2 ) A substance which crystallizes in yellow plates ; used as an oxidizing agent in making coal- tar dyes. CHLORANILINES Chlorinated derivatives of aniline, C 6 H 4 C1NH 2 , C 6 H 3 C1 2 NH 2 , and C 6 H 2 C1 3 NH 2 . CHLORIDE OF LIME CHLORINE 109 CHLORIDE OF LIME See Calcium and Chlorine. CHLORINE (Cl) and its compounds Atomic weight, 35-5; sp. gr., 2'49 ; melting-point, ioi'5C. Chlorine is not found in nature in an uncombined state, but exists very extensively in combination with other substances, and most abundantly in the form of common salt sodium chloride (NaCl). There are large deposits of salt in Cheshire, and it forms part of the well-known Stassfurt saline deposits (in Germany). Combined with hydrogen as hydrochloric acid (HC1), it is a natural constituent of the gastric juice of men and animals. In the form of salt it is always found present in sea- water ; thus, the water of the English Channel contains 28-05 parts per 1,000. Common salt is mined to some extent in an impure state in the dry condition (rock salt), but for the most part (being soluble in water) it is made by pumping water into the salt deposits and subsequent evaporation of the brine solution thus prepared. Chlorine in gaseous form is manufactured on a large scale, and is employed chiefly in the preparation of chloride of lime, or bleaching powder (see Calcium), which is used for bleaching purposes and as a sanitary reagent. For this purpose it is mostly made by the action of hydrochloric acid upon manganese dioxide (see Alkali Trade Chart, p. 18): MnO a + 4HC1 = MnCl 2 + 2 H 2 O + C1 2 . In the Weldon process, the manganese is reprecipitated from the resulting manganese chloride liquor as manganese hydroxide (MnH 2 O 2 ) by treatment with milk of lime and peroxidized by a current of air, ready for use over again. In the Deacon process, which is also employed on a manufacturing scale, a mixture of hydrogen chloride (HC1) gas and air is exposed to the catalytic influence of cupric chloride distributed over a widely exposed surface at a temperature of about 400 C., chlorine and water being produced as follows : There is also an electrolytic method of manufacturing chlorine now in use, consisting in the direct electrolysis of a solution of common salt (brine), in which the gas is evolved at the anode whilst sodium hydrate is produced at the cathode. The concentrated gaseous chlorine thus pre- pared and liquefied, and stored in iron cylinders, was largely used in the great war for " gassing " by reason of its cor- rosive and poisonous character. i io CHLORINEHYDROCHLORIC ACID CHLORINE (Continued) In the liquefied form it is of a bright golden-yellow colour, and when cooled sufficiently it freezes to a yellow crystalline mass. It immediately passes into the gaseous state when liberated in the air, and has a very violent action on the linings of the mouth, nose, throat, and lungs, causing death when inhaled in serious quantity. On account of its sterilizing value, chlorine as such, or in the form of bleaching powder, is frequently used for the purification of water-supplies. Chlorine is also employed in the manufacture of potas- sium chlorate (KC1O 8 ), which is extensively used in match- making and in the preparation of certain explosives and of chloroform. Chlorine gas is of a greenish-yellow colour, and nearly two and a half times heavier than air. It is somewhat soluble in water, i volume of which at 10 C. absorbs 3-1 volumes of chlorine, forming a green solution. When strong chlorine water is cooled to nearly freezing-point, it deposits a crystalline hydrate (C1 2 8H 2 O) of unstable character. Metallic copper in thin leaf form, metallic antimony in the form of a powder, and sodium, all take fire and burn readily in chlorine gas, forming chlorides, although the gas itself is not inflammable. Similarly a jet of burning hydro- gen gas will burn in a vessel containing chlorine gas, thus producing hydrochloric acid in the form of white fumes : = HC1. Hydrochloric Acid, or hydrogen chloride (HC1), is one of the most important compounds of chlorine. The two gases hydrogen and chlorine do not combine when mixed together in the dark, but in sunlight or electric light they combine with explosive violence. The acid can be easily prepared, amongst other methods, by the action of strong sulphuric acid upon common salt as represented by the equation 2 NaCl + H 2 SO 4 = Na 2 SO 4 + 2HC1 ; that is to say, sodium sulphate and hydrochloric acid are produced, and the hydrochloric acid can be distilled over from the mixture in the form of gas and condensed in water, thus furnishing a solution of the acid. In its gaseous form, the acid is colourless and possesses a pungent, irrita- ting character. It is soluble in water, i volume of which at o C. and under ordinary atmospheric pressure dissolves 503 volumes. CHLORINE CHLORIC ACID in CHLORINE (Continued) Hydrochloric acid finds use in the textile and chrome tanning industries, and the manufacture of dyestuffs, and is obtained as a by-product in the manufacture of sodium carbonate from common salt and sulphuric acid, the gas (HC1) being absorbed in condensers by the action of water percolating down towers or stacks packed with broken coke, up which it is led. (See Alkali Trade.) Hydrochloric acid decomposes the oxides and carbonates of the alkaline and other metals, as illustrated by the following equations the first representing the action of the acid upon sodium oxide (Na 2 O), the second that of the acid upon barium oxide (BaO), and the third that upon ferric oxide Na 2 O + 2HCl=2NaCl + H 2 O, BaO + 2HCl = BaCl 2 +H 2 0, Fe 2 3 + 6HC1 =2FeCl 3 + 3H 2 O, the chloride of the base being produced in each case. Car- bonates of the same and many other bases are similarly decomposed. For instance, using sodium carbonate the change is as follows : Na 2 CO 3 + 2HC1 = 2NaCl + H 2 O + CO 2 ; and barium carbonate as follows : BaCO 3 + 2HC1 = BaCl 2 + H 2 O + CO 2 . Hypochlorous Acid (HC1O) is only known in association with water, in which it is soluble, the solution being yellowish in colour and having a chlorous odour. It can be made by a number of processes, notably by the action of any dilute mineral acid, such as hydrochloric acid upon a soluble hypochlorite such as a solution of bleaching powder. Strong solutions of the acid are unstable and apt to decompose with violence, but a dilute one is more stable and exhibits powerful oxidizing and bleaching effects. Sodium Hypochlorite (NaCIO) in solution is used as a sanitary reagent, and more extensively for oxidizing and bleaching purposes. Chloric Acid (HC1O 3 ) is prepared by the action of dilute sulphuric acid upon barium chlorate, but it also is only known in association with water, as a stronger solution than 80 per cent, decomposes, upon heating, into chlorine and water. It is a powerful oxidant, wood and paper being ii2 CHLORINE CHLORITE CHLORINE (Continued) liable to combustion when a strong solution is dropped upon them. The potassium salt (KC1O 3 ) potassium chlorate is an important article of commerce, and was originally made by the action of chlorine upon milk of lime by which calcium chlorate is ultimately formed 6Ca(HO) 2 + 6C1 2 = Ca(ClO 3 ) 2 + 5CaCl 2 + 6H 2 O ; and in a subsequent operation the calcium chlorate was converted into the potassium salt by treatment with potas- sium chloride and crystallized out from the mixture Ca(C10 3 ) 2 + aKCl = 2KC10 3 + CaCl 2 . This process, however, has been superseded by an electrical one in which potassium chloride is directly transformed into the chlorate by the action of the electrical current upon a solution at a temperature of 50 C. Potassium chlorate crystallizes in white tables, is soluble in water to the extent of 3*3 per cent, at o C. and 59 per cent, at 100 C., and is largely used in the manufacture of explosives, percussion caps, matches, and in pyrotechnics. When heated to 380 C. it melts and gives off oxygen, and this affords one method of obtaining that gas. CHLORINATION The name given to any process by which chlorine is imported into a substance ; for example, lime is converted into bleaching powder, or so-called chloride of lime, by the action of chlorine, and some additive and many substitution products are derived from benzene hydrocarbons by the introduction of chlorine, hydrogen being replaced by chlorine in the last-named instances. Thus benzene hexachloride (C 6 H 6 C1 6 ) is an additive substance produced by exposing benzene to chlorine gas for a prolonged period, etc. Methyl chloride (CH 3 C1) illustrates the chlorination act by which hydrogen is replaced by chlorine, and is obtained with other substances when chlorine is permitted to act on methane (marsh gas, CH 4 ). In the preparation of benzyl chloride from boiling toluene by the action of chlorine, the following interaction takes place : C 7 H 8 +C1 2 = C 7 H 7 C1 + HC1. CHLORITE A mineral hydrated double silicate of aluminium and magnesium coloured with iron, often found in associa- tion with garnet, quartz, and calcite. " CHLORODYNE "-CHOLINE 113 " CHLORODYNE " A pharmaceutical compound containing prussic acid, morphia, chloroform, and hemp, having proper- ties of an opiate and an antispasmodic. CHLOROFORM (CHC1 3 ) A halogen substitution product con- stituting a volatile, valuable anaesthetic liquid, prepared from acetone or alcohol by the action of chloride of lime and water. It is also a useful solvent of fats and other substances, boils at 61-2 C., has a sp. gr. of 1*499, and is soluble in alcohol and ether. CHLOROPHYLL The green colouring matter of the leaves and other parts of plants which is only developed when plants are grown in the light. So far as investigation has gone it would appear to be a magnesium compound of the formula Mg,C 55 H 72 N 4 O 5 or Mg,C 55 H 72 N 4 O 6 , and there seems to be some relationship between it and the colouring matter of the blood. It is associated in leaves with two other colouring matters viz., carotin (carrotene), the substance which gives its colour to carrots (said to be a hydrocarbon of the formula C 40 H 56 ), and xanthophyll, a substance of dark brownish-red tint (said to have the com- position C 40 H 56 O 2 , and to be an oxidation product of carotin). Chlorophyll itself is stated to be a mixture of two sub- stances, differing in their spectra and solubility in certain solvents. (See also Plant Colouring Matters.) " CHLOROS "The trade name of a proprietary disinfectant solution containing sodium hypochlorite. CHOKE-DAMP A mixture of carbon dioxide and other poisonous gases met with in coal-workings, particularly after explosions. CHOLALIC ACID (C 24 H 40 O 5 ) See Taurocholic Acid and Bile. CHOLESTEROL (Cholesterine) (C 26 H 44 O) A white, inodorous substance which crystallizes with water (C 26 H 44 O,H 2 O) in beautiful pearly plates, is insoluble in water but soluble in ether and hot alcohol, and melts at i48'5 C. It enters into the composition of gall-stones, the human bile, brain and nerve substance, being present in bile to the extent of about 0*25 per cent, and in brain-matter to about i per cent. It can be sublimed without decomposition at about 300 C. in vacuo. Its formula is sometimes expressed as C 27 H 45 OH + H 2 0. CHOLINE (C 5 H 15 NO 2 ) A basic substance nearly related to neurine, 8 1 14 CHONDRINE CHROMIUM CHONDRINE An albuminous substance resembling gelatine, produced by boiling certain animal tissues, such as cartilages, with water. CHONDRUS See Agar-Agar. CHRISTOBALITE A crystallized form of silica, frequently found in volcanic rocks. CHROMATES See Chromium. CHROME ALUM See Alum (Chrome). CHROME IRON See Chromium. " CHROMETAN " A proprietary reduced chrome made in liquid and crystalline forms for use by tanners. The ordinary liquid has a basicity of 144, and the " basic " variety one of 96 ; when dried, the crystalline variety contains 25 per cent, oxide of chromium. CHROMIC ACID See Chromium. CHROMIUM (Cr) and its compounds Atomic weight, 52 ; sp. gr., 6-92 ; melting-point, 1,615 C. Chromium occurs in nature in combination in a number of minerals, including chrome iron ore or chromite (Cr 2 O 3 FeO), the main source of preparation of chromium, large supplies of which come from New Caledonia, Rhodesia, U.S.A., and Canada. It also occurs in the forms of lead chromate or crocoisite (PbCrO 4 ) and chrome ochre (Cr 2 O 8 ). The higher grades of chromite contain from 40 to 50 per cent, of the oxide, and considerable quantities are mined in California and Oregon (U.S.A.), in Portuguese Africa, and French Oceania. There are also good deposits in Cuba, and it is put to use, among other applications, in the manufacture of chromite bricks for metallurgical use in lining furnaces. In the metallic state, chromium is a hard, steel-grey metal, and is employed for the purpose of imparting hard- ness and tenacity to steel used for making tyres, springs, axles, and armour-plate, by incorporation of from 0-5 to 3 per cent. It is as hard as corundum. The metal is manufactured from its oxide by intensely heating a mixture of it with powdered metallic aluminium, which combines with the oxygen to form alumina (A1 2 O 3 ), metallic chromium being set free in a molten condition. There are two oxides, Cr 2 O 3 (chrome green) and CrO 3 , the former of which, known as chromium sesquioxide, is used as a green pigment and the other (chromic anhydride) constitutes the colouring matter of the ruby, and can be CHROMIUM CHRYSENE 115 CHROMIUM (Continued) obtained in red, needle-shaped crystals. When heated to 250 C. it gives off oxygen, and is converted into the lower oxide 2CrO 3 =Cr 2 O 3 + 3O. It is a powerful oxidant, and when dissolved in water is supposed to produce chromic acid (H 2 CrO 4 ). Potassium Chromate (K 2 CrO 4 ) is a yellow crystalline body, soluble in water ; whilst the dichromate (K 2 Cr 2 O 7 ), which is also soluble in water, crystallizes in red prisms, and is manufactured on a large scale, not merely on account of its uses in tanning, bleaching, and as an oxidizing agent, but chiefly for the preparation of the various well-known chrome pigments, including "chrome yellow," or lead chromate(PbCrO 4 ). It also finds some use in photography, as when a film of gelatine is treated with a solution of that substance it is rendered insoluble by the chemical change that ensues. Sodium Bichromate is also used to some extent in certain processes for tanning leather. Chromium Borate is used as a pigment in calico-printing. Other chromium compounds include : Chromium chloride (CrCl 8 ) and its hydrate (CrCl 3 6H 2 O), which is soluble in water and used as a mordant ; Chromium phosphate (CrPO 4 ) (Plessy's green), insoluble in water and used as a pigment ; Chromium sulphate (Cr 2 (SO 4 ) 3 ) and its hydrate (Cr 2 (SO 4 ) 3 15H 2 O), the former being insoluble, but the second soluble in water and used in the textile trades ; Chromium potassium sulphate (K 2 SO 4 ,Cr 2 (SO 4 ) 3 .24H 2 O), a violet-red crystalline salt, soluble in water, used as a chrome tan liquor and in the textile industry (see Alum chrome) ; and Chromium acetate (Cr(C 2 H 3 O 2 ) 3 .H 2 O), a greenish powder soluble in water, also used in the textile trades. CHRYSAMINE A substantive yellow coal-tar dye used in the leather and textile trades, prepared from salicylic acid. CHRYSENE (C 18 H 12 ) A white crystalline hydrocarbon con- tained in the coal-tar distillate which comes over above 360 C. It melts at 250 C., boils at 448 C., and resembles anthracene in properties. 1 1 6 CHRYSOBERYL CINCHONA CHRYSOBERYL A natural combination of the oxides of aluminium and beryllium (Al 2 O 3 BeO). CHRYSOIDINE An orange-red colour which dyes silk and wool directly. It is a hydrochloride of diamido-azobenzene (C 6 H 5 N 2 ,C 6 H 3 (NH 2 ) 2 HC1), and is slightly soluble in water. CHRYSOLITE (Peridot, Fibrous serpentine) Natural crystals of olivine (magnesium silicate). CHRYSOPHANIC ACID (Chrysarobin) (C 30 H 26 O 7 ) A medi- cinal body prepared from Araroba (Goa powder), which is deposited in the wood of Vouacapoua araroba. It is soluble in water, alcohol, and ether, and melts at 157 C. CHYLE The digested alkaline fluid resulting from the con- version of chyme by action of the biliary and pancreatic juices, being thus prepared ready for absorption by the lacteals of the intestines and conversion into blood. CHYME The stomach-digested food before it is acted upon by the bile and pancreatic juice. CIDER Fermented juice of apples, containing from 5 to 9 per cent, alcohol. CIMOLITE A hydrous mineral aluminium silicate. CINCHONA (Peruvian bark, Loxa bark, Red Peruvian bark, etc.) The bark of the stems and branches of various species of cinchona and other genera of the Rubiacea order, growing in the Cordilleras and elsewhere between the latitudes 10 N. and 19 S. The chief supplies are obtained from Java, India, and Ceylon. The output of quinine from the Indian factories for the three years 1916-18 reached an average of 64,000 Ib. per annum. A number of im- portant bases or alkaloids are contained in these barks, includ- ing quinine (C 20 H 24 N 2 O 2 .3H 2 O), cinchonine (C 19 H 22 N 2 O), quinidine (C 20 H 24 N 2 O 2 ), and cinchonidine (C 19 H 22 N 2 O), the two last named being regarded as probably stereoiso- meric with the two former. Quinine is a white, crystalline alkaloid, which melts at 177 C., is soluble in alcohol and ether, and is intensely bitter. The sulphate and chloride are both used as febri- fuges and otherwise in medicine, as also the acetate, benzoate, phosphate, salicylate, tartrate, tannate, citrate, and glycerophosphate. The sulphate is a white, crystalline powder soluble in water to the extent of i in 350 parts, has a bitter taste, and in solution exhibits a strong fluorescence. CINCHONA CINNAMIC ACID 117 CINCHONA (Continued) Ninety-seven per cent, of the world's production of quinine is obtained from Java cinchona bark, although the resources of the British Empire are sufficient, if utilized, to be independent of Holland. One method of preparing quinine consists in mixing the finely ground bark with powdered lime and extracting the mixture with hot high-boiling paraffin oil, and, after filtra- tion, shaking the filtrate with dilute sulphuric acid. The acid solution is then neutralized with sodium carbonate solution, and upon cooling the quinine sulphate crystallizes out. The alkaloid can be obtained from the sulphate by treatment with ammonia. Cinchonine is a white, crystalline body, slightly soluble in water, alcohol, and ether, with a melting-point of 2643 C. The hydrochloride, nitrate, and sulphate are all soluble in water and alcohol. Cinchonidine is a white, crystalline body, soluble in alcohol, of melting-point 207*2 C. Conchinine (Quinidine) is colourless and crystalline, of efflorescent character, and is soluble in alcohol and ether, having a melting-point of 171*5 C. All the antifebrile barks are used medicinally in the form of tinctures and infusions, on account of their valuable febrifuge and tonic properties, as are also those of the separated alkaloids and their sulphates. CINCHONIDINE See Cinchona. CINCHONINE See Cinchona. CINEOL (C 10 H 18 O), otherwise known as cineole and eucalyptol, is found in many essential oils, and is the predominating constituent of the oils of cajuput, wormseed, and Eucalyptus globulus. It is derived from terpin hydrate (C 10 H 22 O 3 ) by dehydration, and is a colourless liquid of characteristic camphoraceous odour, soluble in ether, with a sp. gr. of 0*9267, boiling-point 176 C., and melting-point - i to 3 C. CINNABAR Native sulphide of mercury, a deposit of which has recently been discovered in the Aguas Blancas district, in Chile, near Antofagasta. CINNAMIC ACID (C 9 H 8 O 2 ) A white, crystalline derivate of benzene found present in Peru and Tolu balsams, and liquid storax, soluble in alcohol, ether, and hot water, and which yields benzoic acid upon oxidation. It is monobasic, ri8 CINNAMIC ACID CITRATES CINNAMIC ACID (Continued) melts at 133 C., and forms a large variety of crystallizable salts. CINNAMIC ALCOHOL (Styrone or Cinnamyl alcohol) (C 6 H 5 CH:CH:CH 2 OH) crystallizes in white needles, is soluble in alcohol and ether, has an odour like that of hyacinths, and is used in perfumery. It occurs as cinnamic ester (styracin) in storax, and is prepared from that sub- stance by the action of potassium hydroxide, followed by distillation. Its sp. gr. is 1*0397, and it boils at 257 C. By oxidation it yields cinnamic acid, and when the oxidation is more vigorous, benzoic acid. CINNAMIC ALDEHYDE (Q,H 8 O) An aromatic oily body which boils at 246 C., forming the chief constituent of cinnamon oil (from Persea cinnamomum). CINNAMON The inner bark of trees of the genus cinnamomum which grow in Ceylon, and is a well-known spice, which yields from \ to i per cent, of the essential oil of cinnamon, which is prepared from it by distillation, using salt water, and contains cinnamic aldehyde (C 9 H 8 O) and eugenol. The oil possesses an aromatic pleasant odour and taste, and is used for flavouring and medicinally as a stimulant. It has a sp. gr. i '024 to 1*04, refractive index 1*59 to i'6o, and a rotation of o to i. Cinnamon leaf oil is distilled from the leaves of the Cinnamomum zeylanicum. It is pale yellow, having a charac- teristic spicy odour, contains cinnamic aldehyde and safrol, has a sp. gr. of 1*044 to I and rotation -25 to -40. CUDBEAR CUTTLE-FISH 147 CUDBEAR A colouring matter prepared from certain lichens like Archil. CULM Anthracite. CUMENE (C 9 H 12 ) A liquid homologue of benzene, of sp. gr. 0-862, existing ready formed in Burmese naphtha, and produced by the distillation of cumic acid (C 10 H 12 O 2 ), or by heating a mixture of cumic acid and baryta. It is soluble in alcohol and ether, and used for sterilizing catgut. CUPELLATION An operation conducted in a cupel that is, a shallow, oval-shaped, bone-earth or other dish which is heated in a reverberatory furnace in course of assaying or testing of metals or ores ; for example, argentiferous lead, rich in silver, which, when treated in this way in a current of air, is decomposed, the lead being converted into oxide (litharge), which melts and is absorbed by the bone-earth cupel, or is blown over by the air-current, leaving the metallic silver in the cupel. CUPFERRON (C 6 H 5 (NO)ONH 4 ) The ammonium salt of nitrosophenylhydroxylamine. It is a crystalline body soluble in water, used in the practice of quantitative analysis for separating copper and iron from other associated metals, they alone being precipitated by cupferron from strongly acid solutions. The precipitate is washed on a filter first with water and then with ammonium hydrate, which dis- solves the copper but not the ferric compound, which is soluble in chloroform, ether, and acetone, and may thus be obtained free from other associated metallic salts. The ferric compound can be converted into oxide by ignition and weighed as such. Its use is limited by reason of its explosive character. CUPRITE A mineral copper oxide (Cu 2 O). CURARA A resinous body extracted from plants of the genus strychnos, and used by the Indians of South America for poisoning their arrows. The active principle is named curarina, a yellow substance, soluble in water and alcohol. CURCUMIN Turmeric yellow. CUTCH A tanning material, being the catechu of the Mimosa catechu or Acacia catechu. It is a hard brownish-black substance prepared in India, and is apparently of glucoside character. (See Catechu and Tannins.) CUTTLE-FISH A molluscous animal of the order Cephalopoda and genus sepia, possessing a so-called "ink-bag" a gland near the liver from which it discharges, when pursued, a dark-coloured liquid, which discolours the water and 148 CUTTLE-FISH CYA N1DES CUTTLE-FISH (Continued) obscures its passage. It is from this material that the sepia of painters is prepared, by dissolving it in potassium or sodium hydrate, reprecipitation with hydrochloric or sulphuric acid, washing and drying. Sepia is dark brown in colour and of fine grain, and is stated to consist of a mixture of calcium and magnesium carbonates, melanin, and an organic colouring matter. CYANAMIDE (CN 2 H 2 ) is a colourless, crystalline body, pre- pared from cyanogen chloride and an ethereal solution of ammonia. It is deliquescent, melts at 40 C., is soluble in water, alcohol, and ether, and behaves chemically both as a weak base, forming crystalline salts with acids, and as a weak acid, yielding sodium, lead, silver, and calcium com- pounds. The calcium derivative is commercially produced by heating calcium carbide to about 1,000 C. (in the presence of a little calcium chloride) in a current of air or nitrogen CaC 2 + N 2 =CaCN 2 + C, or by passing nitrogen over a mixture of lime and carbon electrically heated to 2,000 C., an excess of carbon being used. The crude product is a black powder containing from 20 to 23 per cent, of nitrogen, and is used as a fertilizing agent under the name of " nitro-lime." The other constituents of nitro-lime are about 20 per cent, of free lime, 7 to 8 per cent, of silica, alumina, and iron, and 14 per cent, of carbon in the form of graphite. Under the influence of superheated steam, cyanamide gives off its nitrogen in the form of ammonia. (See Calcium Carbide.) CYANIC ACID (CNHO) is a mobile liquid of pungent odour and unstable nature, changing with explosive violence into cyanuric acid and cyamelide when removed from a freezing mixture. By combination with bases it forms cyanates, including ammonium cyanate, which gradually undergoes change at ordinary temperatures, and at 100 C. is quickly resolved into urea, as expressed by the following formula CNO(NH 4 ) = CO(NH 2 ) 2 . This is a striking instance of isomeric change by atomic reconstruction brought about by a physical cause. (See Isomerism.) Potassium cyanate is a white crystalline salt readily soluble in water and alcohol. CYANIDES See Hydrocyanic Acid and Cyanogen. CYANOGEN DARIN'S SOLUTION 149 CYANOGEN (C 2 N 2 ) A very poisonous, colourless gas, soluble in water and alcohol, having an odour something like that of bitter almonds, and which behaves in many respects as a halogen, the group CN playing the part of a radical, It is obtained by heating mercuric cyanide and collecting it over mercury (as it is soluble in water), and can be con- densed to a colourless liquid of sp. gr. i'8. It is inflam- mable, and when burned it is resolved into carbon dioxide and nitrogen. In combination with hydrogen it forms hydrocyanic acid (HCN). (See Hydrocyanic Acid.) Carbon and nitrogen do not combine directly, but heated together with an alkali such as potassium carbonate, the corresponding cyanide is formed in this case, potassium cyanide (KCN). The cyanides of the alkali and alkali-earth metals are all soluble in water, but those of the heavy metals, excepting mercury cyanide, are insoluble in water. The potassium and sodium cyanides are largely used in the extraction of gold and silver from their ores, also in electro-plating and other industries. Cyanogen compounds are made on an extensive scale from nitrogenous organic matters, such as the clippings of hoofs and hides ; thus, when heated with iron and potash, potassium ferrocyanide is produced. (See Potassium.) " CYLLIN " A proprietary coal-tar disinfectant fluid, emul- sifying with water. CYMENE (C 10 H 14 ), also known as cymol, is found present in the volatile " cummin" oil (obtained from Cuminum cyminum) in water-hemlock seeds, and in oil of thyme. It is nearly related to camphor (C 10 H 16 O) (from which it can be readily obtained by a process of dehydration) and to the terpenes (C 10 H 16 ), from which it can also be prepared. It boils at 175 C., has a sp. gr. of 0-856, is soluble in alcohol and ether, is colourless, and has an agreeable, somewhat cam- phoraceous and lemon-like odour. CYTASE One of the enzymes in germinating barley which attacks and destroys the cell walls, thus exposing the starch content to the action of the diastase. DAKIN'S SOLUTION An antiseptic liquid, 10 litres of which can be prepared according to the following approved formula: chloride of lime, say 156 grms. ; anhydrous sodium carbonate, 78 grms. ; anhydrous sodium bicarbonate, 65 grms. The chlorinated lime is first of all digested with 5 litres of water and subsequently filtered, and the other i5o DA KIN'S SOLUTION DECOMPOSITION DAKIN'S SOLUTION (Continued) ingredients are then dissolved in water, and the solution mixed with that of the chloride of lime and made up to 10 litres. (See Eau de Javelle.) DAMMAR A RESIN (Dammar gum) of commerce melts at about 120 C,, and is of two varieties, one of which is known also as "cowdie gum," the produce of a large conifer (Dammara australis), which occurs in whitish-yellow masses and smells like turpentine. The other, of East Indian origin and known also as " cat's- eye resin," comes in the main from Singapore and is the pro- duce of another coniferous tree (Pimis dammara or Dammara alba). It has a resinous odour and is the better known of the two varieties. Both kinds are soluble in turpentine, alcohol, and ether, and are used in the manufacture of varnishes and lacquers. DANAITE A cobaltiferous mispickel. DEAD OIL The " heavy " oil obtained from the distillation of coal tar. DEOANTATION Pouring off or decanting a liquid from a sediment or deposit. (See also Siphon.) DECOCTION An infusion or extract prepared by heating or boiling a crude material with a solvent for the purpose of extracting its soluble constituents. DECOMPOSITION A chemical compound can be broken up into its constituent parts by chemical or physical means, and is then said to be decomposed. Decomposition is the breaking up of a compound into its parts by means of a greater force than that of the chemical affinity which binds them together. There are many ways or methods of effecting the decom- position of chemical compounds. Some can be readily decomposed by heating ; in others an electric current passed into them in a molten state or into their solutions will effect the purpose ; whilst in yet other cases mere exposure to light suffices, many of the silver compounds, for example, suffering chemical change in this way, and practical advantage of this fact is taken in the art of photography. Water consists of a combination of two gases, named hydrogen and oxygen, and it can be decomposed or broken up into them again by passing a current of electricity through it. DECOMPOSITION DEGRA S 151 DECOMPOSITION (Continued) Limestone, of which the common limestone rock is chiefly composed, is a chemical combination of lime and carbon dioxide, and when it is strongly heated as is done practically in lime-kilns it is broken up or decomposed into the two parts. The lime which is left in the kiln is itself a chemical compound of a more simple nature, con- sisting as it does of the metal calcium and the gas oxygen, whilst the carbon dioxide gas which escapes from the kiln is also a chemical compound of an element named carbon (which forms the chief constituent of charcoal and the precious stones known as diamonds) with oxygen (which is one of the constituent gases of air). The yellow mercury oxide can be broken up or decom- posed into its two constituents by exposing it to a greater heat than that which is necessary to produce it from the mercury and oxygen of which it is composed. DECORTICATION The shelling of seeds intended to be sub- sequently crushed to extract the oil contained in them by pressure or the action of solvents. DECREPITATION Physical rending or flying apart of the joints of the crystalline structure of certain minerals and salts when heated, attended with a crackling noise. Com- mon salt and calcspar exhibit this behaviour. DEFECATION Processes of purification or freeing from dregs. DEFLAGRATIONA rapid combustion with evolution of light and heat, as when a strip of magnesium foil is burned in oxygen gas. A mixture of nitre with antimonious sulphide, thrown into a red-hot crucible, burns with deflagration, the sulphur being oxidized by the oxygen of the nitre. DEFLAGRATING-SPOON A metallic wire or rod terminating at the lower end in a small iron or other metallic spoon or cup to hold the desired chemical substance, and fitted above with a metallic plate or with a cork, which may be adjusted beforehand, to fit a wide-mouthed stoppered jar or bottle, in which it is planned to make the experiment. Such an appliance can be used to illustrate the burning of phosphorus in oxygen gas as referred to under the heading of Chemical Interactions. DEGRAS A crude grease obtained from sheep's wool, used as a leather dressing. (See also Adeps Lanae and Suint.) 152 " DEKA LINE "DEPILATORIES 11 DEKALINE " (Decahydronaphthaline) (C 10 H 18 ) A proprie- tary substitute for turpentine, used as a solvent, also as a substitute for lamp, motor, and lubricating oils, with a dis- tilling-potnt of 190 C., flash-point 60 C., and sp. gr. 0-9. It is prepared by treating naphthaline in a fused state and at a temperature above 100 C. with hydrogen in the presence of a catalyst such as finely divided nickel. It is of aromatic character, with an odour something like that of camphor, and can be used as a cleansing fluid for machinery, particularly printing machines, and for removing stains from garments. As a solvent, it is stated to be equal to turpentine, and it is somewhat slower in evaporation than that liquid, which is a point in its favour for some applica- tions. DELIQUESCENCE Absorption of moisture from the air, whereby substances become pasty or more or less liquid in character; common salt, for example, is a deliquescent substance, and calcium chloride is a very deliquescent compound. (See Drying-Tube.) Some crystalline substances when exposed to the air combine with the moisture contained therein and pass into other distinct crystalline forms, and in certain instances the combination continues to such an extent that the substance liquefies. DELPHININE (C 22 H 35 NO 6 ) A white, crystalline, poisonous alkaloid, soluble in alcohol and ether, extracted from the seeds of Delphinium staphisagria, or larkspur. DEN ATURANTS Substances introduced into alcohol made for industrial purposes to prevent its consumption as drink, such as paraffin oil, pyridine, camphor, and benzene. DENSITIES Relative weights compared with a standard. Water is taken as a standard of comparison for liquids and solids, whilst hydrogen gas is ordinarily taken as that of gases. (See Hydrometer, Molecules, and Specific Gravity.) DEOXIDATION The taking away of oxygen as a constituent of a substance; for instance, iron oxide is deoxidized by heating with carbonaceous material, as in smelting, thus reducing it to the metallic state. Barium dioxide is de- oxidized to the state of barium monoxide by heating it to a certain temperature. DEPILATORIES Chemicals used for the removal of hair from skins, such as the alkaline sulphides used in the leather industry. DERBYSHIRE SPAR DEVITRIFICATION 153 DERBYSHIRE SPAR See Fluorine. DERMATOL Bismuth subgallate, used in medicine. DESICCATE To dry, denude, or rob of water. DESICCATOR A drying appliance designed to remove water from chemical substances. A common form consists of a segmented porcelain basin containing strong sulphuric acid, standing on a glass plate having a ground surface and covered with a closed bell-jar, having also ground edges slightly coated with grease. The liquid or solid preparation to be dried (desiccated) -is pi placed in a smaller vessel Of glass Or . N B _ Th ; s pigure of an A ir-Putnp and Desic- platmum Or Other cator does not show the Sulphuric Acid Basin. material on the ves- sel containing the strong sulphuric acid, which, having a strong affinity for water, absorbs the moisture evaporated from the substance undergoing the drying process. Some- times this appliance is coupled up with an air-pump to facilitate the process. By greasing the plate as well as the edges of the bell-jar, the combination is made airtight. (See Air- Pump.) DETONATORS Copper tubes containing a charge of mercuric fulminate alone or mixed with potassium chlorate or other ingredients. Other detonating substances include an aniline derivative named " tetryl " (tetranitroaniline), lead triazide (PbN 6 ), etc. Detonation requires to be started by a strong impulse such as that imparted by the explosion of a charge of mercury fulminate ; it proceeds very rapidly, and is due to the formation of an explosion wave having a velocity of thousands of metres per second. In blasting operations detonators (like gunpowder) are either fired by a time-fuse or electrically. DETRITUS Redeposited matter worn off rocks. DEVITRIFICATION Loss of opacity or vitreous character of glass. 1 54 DE W-POINTDIA STA SE DEW-POINT The temperature at which the atmospheric air is saturated with moisture and begins, in consequence, to deposit it. (See Air, p. 9.) DEXTRINE See Starch. DEXTRO-LIMONENE A terpene (C 10 H 16 ) constituent of several essential oils. DEXTROSE (C 6 H 12 O 6 ) A soluble carbohydrate, dextro- rotatory in character, and otherwise known as glucose and grape-sugar, prepared from cane-sugar by inversion and from starchy bodies by action of mineral acids ; but, as thus made, it contains dextrine and other unfermentable bodies in association. It is largely used in brewing, con- fectionery, preparing tobacco, and in chrome tanning liquors. (See Invertase.) DIABANTITE An uncommon member of the chlorite group of complex mineral silicates. DIALYSIS A sort of diffusion by means of which a liquid which contains, say, a mixture of a crystallizable substance such as salt or sugar, with another (colloid) which is not crystallizable, such as albumin or gum, can be separated. This is effected by placing the mixture jn a tray or other vessel having as its bottom a sheet of parchment paper or animal membrane, such as bladder, etc., and floating or suspending this vessel in a dish of water, when the crystal- lizable substance in solution dialyzes or diffuses through the parchment dialyzer into the water outside, and the colloidal substance in solution remains behind in the containing vessel. Colloidal solutions are not utterly devoid of the property of diffusion, but as the size of the constituent particles is great in comparison with that of the molecules they diffuse very slowly as compared with crystalloids. (See Colloid and Osmosis.) DIAMINOPHENOL (C 6 H 4 (NH 2 )C 6 H5) The ortho and para varieties of this substance are greyish-white and crystalline, and are used as photographic developers. DIAMOND The purest form of crystallized carbon, the sp. gr. of which is 3-5. It is of great hardness. There are deposits in South Africa, Brazil, India, and elsewhere. DIAPHANOUS Transparent to light. DIASTASE An amorphous active principle or enzyme, soluble in water, contained in extract of malt, capable of turning starch into soluble substances, including ferment- able sugar. (See Beer, Enzymes, and Malt.) DIA THERM A NO US DIFFUSION 1 5 5 DIATHERM ANGUS A character of substances like rock- crystal which transmit heat as transparent substances transmit light. DIATOMITE (Diatomaceous Earth) A form of kieselgiihr or siliceous deposit. (See Silicon.) DICHROISM The property possessed by double-refracting crystals of exhibiting two colours when viewed in different directions. (See Crystals and Fluorescence.) DIET See Foods. DIETHYLAMINE See Amines. DIETHYLANILINE (C 6 H 5 .N(C 2 H 5 ) 2 ) A yellowish-brown, in- flammable liquid obtained by heating a mixture of aniline, aniline hydrochloride, and ethyl alcohol. It boils at 2i3'5 C., is soluble in alcohol and ether, and employed in the manufacture of synthetic dyes. DIFFUSION Widely spreading or extending; a property particularly exhibited by gases, all of which mix together or diffuse into each other without chemically combining and in a much more complete sense than certain liquids are miscible with each other. The relative velocities of diffusion of any two gases are inversely as the square roots of their densities. Vinegar and water placed together in a bottle and shaken, gives a mixture of dilute vinegar of which every drop is identical with every other drop. Other liquids, however, will not mix together for example, oil and water ; but all gases will mix together. Oxygen and nitrogen, for example, as they exist in the air are thoroughly admixed, and every part of the air is identical in composition with every other part ; that is to say, the proportions of their chief constituents, oxygen and nitrogen, are uniform. Gases have the property of mixing with, or diffusing into each other more than liquids, while solids have to be forcibly mixed together to effect a mixture, and even then such a mixture is never an absolutely perfect one ; it is only at best what may be called an imperfect "mechanical" mixture. Some solids, such as the metals tin and lead, melt or fuse upon being heated sufficiently, and in this molten or fused state some of them can be mixed together. (See Alloys.) Similarly, fats melt on the application of heat, and when melted they can be mixed together (ad- mixed). (See also Dialysis and Osmosis.) 1 56 DIGEST DIPENTENE DIGEST To steep in or expose a substance to the digestive action of a solvent liquid. DIGESTION (Animal) See Saliva, Chyme, Chyle, Bile, and Pancreatic Juice. DIGITALIS A genus of plants of which the common fox- glove is the best-known species (Digitalis purpurea), con- taining as active principle digitoxin or digitalin (Q, 4 H 70 O 14 ), which is soluble in water and actively poisonous. The herb itself is used in medicine as a diuretic and for retard- ing circulation. DILL OIL Distilled from the fruit of Anetkum graveolens, contains limonene and carvol, has a sp. gr. of from 0*90 to 0-92, optical rotation + 70 to 80, and is soluble in alcohol and ether. It is of pale yellow colour and characteristic odour, and is used in perfumery and for flavouring. DILUENTS Liquids used for diluting solutions by addition thereto. DILUTE Weak in strength. (See Solution.) DIMETHYLAMINE See Amines. DIMETHYLANILINE (C 6 H 5 .N(CH 3 ) 2 ) An oily derivative of aniline which boils at 192 C., has a strong basic character, and is used in the synthetic manufacture of dyes. By a process of mild Oxidation it is converted into methyl violet, and by a process of reduction it yields the dye " malachite green." DIMETHYLSULPHATE ((CH 3 ) ? SO 4 ) is a colourless liquid of sp. gr. 1 35 and boiling-point 188 C., with a pleasant ethereal odour, used for methylating amines and phenols in the dyestuffs and synthetic perfumes industries, and has also been used as a military poison gas. It is very poisonous ; its fumes produce violent inflammation of the larynx, bronchial tubes, and eyes, whilst the liquid blisters the skin and produces bad sores. DIMORPHOUS The property of crystallization in two forms, as exhibited, for example, by sulphur. (See Crystalliza- tion and Sulphur.) DIPENTENE (C 1Q H 16 ) A sweet-smelling terpene constituent of some essential oils, as, for instance, Oleum cince, in which it is associated with lineol. It can be produced from pinene by the influence of dilute alcoholic sulphuric acid or from sylvestrene and other terpenes by several methods. Sp. gr. 0-85, boiling-point 181 to 182 C. DIPPEL'S OIL DOLOMITE 157 DIPPEL'S OIL A very uncertain mixture of substances of unpleasant odour obtained by the destructive distillation of bones from which the fat has not been previously abstracted, as used for the preparation of bone-black. It contains, amongst other constituents, ammonia, benzene, and a number of pyridine bases, and has a sp. gr. of about O'QOO to 0-980. DISINFECTANTS Preparations that destroy in any way the infectants or causes of disease, or render them innocuous. DISINTEGRATORS Machines for grinding, granulating, or shredding materials. DISSOCIATION Spontaneous or forced acts of decomposition. For example, when steam is heated sufficiently, it is forcibly decomposed into hydrogen and oxygen, or, in other words, its constituent elements are dissociated. Again, ammonium carbonate on exposure to the air breaks up, or is dissociated, into ammonium bicarbonate and ammonia. DISSOLVE The act by which a substance goes into solution, as, for example, when salt is dissolved in water, wax in turpentine, or oil in alcohol. The absorption of moisture by the air is also an act of solution. DISTILLATION The process of converting a substance into vapour and then condensing same. As applied to liquids, it may be termed " wet distillation," but the method is also used in respect of many volatile solid substances, and it is then termed " dry distillation." For example, metallic mercury and zinc can be distilled. " Destructive distilla- tion " means the subjection of materials to heat to such an extent that they are decomposed, and it is the products of this destructive distillation that pass over from the retorts and are condensed fractionally or collectively. This occurs in the cases of resin distillation, coal distillation, the distillation of wood, and the " cracking " of petroleum. (See Retort.) DISTILLED WATER is commonly used in laboratories for making chemical reagents and for solvent and washing purposes generally, because ordinary water contains small quantities of mineral substances, and requires, in fact, to be distilled in order to get rid of such impurities. (See Water- Oven.) DOLOMITE A rock consisting of varying proportions of calcium and magnesium carbonates. (See Magnesium.) 158 DOPE DRYING-TUBES DOPE is a common name given to various solutions or varnishes made by dissolving cellulose or cellulose compounds in cer- tain solvents, including acetone, amyl alcohol, amyl acetate, dichlorethylene of sp. gr. 1*25, boiling at 55 C. ; trichlor- ethylene of sp. gr. 1-47, boiling at 88 C.; perchlorethylene of sp. gr. 1*62, boiling at 121 C. ; tetrachlorethane of sp. gr. 1-6, boiling at 147 C. ; pentachlorethane of sp. gr. 1-7, boiling at 159 C. A small addition of boric acid is some- times made to cellulose dopes in order that they may retain their viscosity. It has been stated that 5 to 8 per cent, of ammonium phosphate or ammonium magnesium phosphate added to cellulose nitrate renders it fire-resistant, and qualifies it to compete with cellulose acetate as an aero- plane dope. (See also Cellulose and Viscose.) DRAGON'S BLOOD A red resin of several varieties secreted by the fruits of a number of palms of the genus Calamus draco, indigenous in Sumatra and the West Indies. It contains benzoic acid in combination, and is chiefly used for colouring mahogany varnishes, in preparing gold lacquers, in compounding dentifrices, and for staining marble a red colour. (See Resins.) DRIERS See Paints and Varnishes. DROP-BOTTLE A simple appliance for providing drops of liquids for testing purposes, consisting of a bottle fitted with a long, tapered, solid glass stopper so that when the stopper is withdrawn a small quantity of the liquid adheres to it and may be dropped into any solution or on to any solid substance to be tested. Another arrangement somewhat similar is a hollow tube or small pipette that passes through the cork, and is drawn out to a fine point at the lower end. By use of the com- pressible rubber bag at the upper end of the tube, as much of the liquid as is desired may be retained in the tube and removed for testing purposes. DRYING-OVEN See Water-Oven. DRYING-TUBES Appliances used for drying gases (freeing them from water), some being straight-shaped tubes packed with small lumps of calcium chloride (CaCl 2 ), which sub- stance has a great affinity for moisture. Another variety consists of a U-shaped tube sealed at the bend with strong sulphuric acid, as it also has the property of absorbing moisture contained in gases bubbled through it, such, for example, as those which are generated by burning organic substances in a current of dry air or DRYING-TUBES DYER'S BROOM 159 DRYING-TUBES (Continued) oxygen. The increase in the weight of the tube gives the weight of the water thus absorbed, from which may be calculated the proportion of hydrogen contained in a known weight of the organic substance employed. (See Organic Analyses.) DRY ROT A chemical decomposition of wood or changes of composition induced by the agency of fungi (especially Polyporus hybridus and Thelaphora puteana) and other causes ; the proportion of carbon and hydrogen contained in the wood being reduced by the production of carbon dioxide and water. In other words, it is an act of slow oxidation accompanied by a loss of density of the wood until the latter, as in the case of hollow tree trunks, becomes rotten. Furniture and the woodwork of houses are liable to attack by the larvae of certain beetles, of which some five species occur in this country, the common furniture beetle being the Anobium punctatum De J., while the death-watch beetle Xestobium rufovillosum De J. more usually affects the timber of old houses, and the powder-pest beetle (Lyctus) mostly affects sapwood. Heat-treatment is the best remedy when applicable; otherwise fumigation with a poisonous vapour such as formaldehyde or the application of powerful insecticides such as "okol," benzene, and carbon tetra- chloride. DUCTILITY Admitting of being drawn into wire. (See Metals.) DUGONG OIL See Fish Oils. DULCITOL or DULCIN or DULCITE (C 6 H 14 O 6 ) A white, crystalline, saccharine body, soluble in water and isomeric with mannite (mannitol), obtained from the dried herb Melampyrum memorosum at the flowering time. DUROGLASS A trade name for borosilicate resistance glass- ware. " DUROPRENE " A proprietary article in the nature of a chlorinated rubber compound (heptachloride of rubber) used in compounding paints for the prevention of rust on metals, etc. It is a greyish-white powder, soluble in benzole, naphtha, and carbon tetrachloride, and is easily moulded when warmed. DYER'S BROOM (Genesta tinctoria) Found in pastures and thickets in Southern Europe, Russian Asia, Southern Sweden, and some parts of Great Britain ; contains two principles, one of which is a yellow colouring matter of 160 DYER'S BROOM DYES AND DYEING DYER'S BROOM (Continued) crystalline character and another genistein (C 14 H ]0 O 5 ), which can be obtained in the form of colourless crystals. DYES AND DYEING There are an immense number of dyes, some being natural products, such as madder, indigo, logwood, and safflower; but for the most part, they are chemically produced substances from coal-tar sources (see Intermediates), and the manner in which the dyes become attached to the fabrics also varies according both to the chemical constitution of the fabrics themselves and those of the dyes employed. In some cases, definite compounds are formed by the action of the dyes on the fabrics ; in other cases, " lakes " are formed by the action of a mordant, the precipitated substance being thus directly attached to the fabrics, and in yet other cases the dyes are developed on the fibres. Basic dyes, including mauve, magenta, methylene blue, malachite green, and Bismarck brown, are fixed on cotton goods by the use of acidic mordants; acidic dyes, including picric acid, azo-scarlets, and aniline blue, are attached to wool and silk goods by the use of an acid-bath. Other acidic dyes, such as alizarin red, require the use of a metallic mordant. Dyes of a saline nature, like the Congo-red series and primulin, are used for cotton and linen without any mordant, and there are pig- ment dyes, such as chrome yellow, synthetic indigo, and aniline black, in respect of which the colour is developed on the fibres. The dyestuffs are also classed as "substantive" and " adjective ": the former have the property of dyeing fibres directly, while the latter will only colour them permanently when used in association with mordants. The so-called " sulphur " dyes are largely made from dinitrophenol (C 6 H 3 (NO 2 ) 2 OH), "sulphur black" being made from it by the action of sodium sulphide and sulphur. The so-called " ciba " dyes are indigo derivatives con- taining bromine. As a rule, cotton goods will not dye without previous treatment with a mordant, the mordant in such cases directly combining with and thus fixing the dye and the mordants used ; for acid dyes, feeble bases like aluminic, chromic, and ferric hydroxides (which are produced on the fabrics by immersing them in solutions of the acetates of these bases and steaming them) are used, the colours of the " lakes" so produced varying with the base employed. Using basic dyes for cotton goods, these are first mordanted with DYES AND DYEING EFFLORESCENCE 161 DYES AND DYEING (Continued) tannic acid or a tin salt, such as the chloride. (See also Azo-dyes, Flavone, Plant Colouring Matters, Rosanilines, and Triphenylmethane.) DYNAMITE See Explosives. DYNAMO See Electricity. DYSPROSIUM (Dy) Atomic weight, 162-5. An exceedingly rare and but little known element. EARTH See Matter. EARTHENWARE See Porcelain EARTH-NUT OIL See Arachis Oil. EARTH-WAX Ceresin. (See Waxes.) EAU DE COLOGNE A solution of various essential oils in alcohol prepared as a perfume. EAU DE JAVELLE A dilute solution of sodium hypochlorite at one time commonly used in France for bleaching and disinfecting purposes. It can be prepared by treating a solution of calcium hypochlorite with one of sodium carbonate and filtering off the precipitated calcium car- bonate. EBONITE See Vulcanite. EBONY The black heart-wood of Diospyws ebenum, which grows in Ceylon, Madagascar, etc. EBULLIOSCOPE A form of apparatus for determining the boiling-points of liquids. EBULLITION Boiling. EDUCT A body separated or brought to light by the splitting up of a substance in which it previously existed in chemical association, and not actually produced by the decomposition. EFFERVESCENCE Escape of gas from a liquid or mixture, as, for example, when hydrochloric acid is poured on marble, carbon dioxide gas is evolved ; or as, again, when soda- water (which is water charged under pressure with the same gas) is allowed to escape from a siphon. EFFLORESCENCE Salts which give up or lose a part of their water of crystallization on exposure to the air and thereby become coated with a pulverulent deposit due to this change, are described as efflorescent. ii 162 EFFLORESCENCE ELECTRICITY EFFLORESCENCE (Continued) Common washing soda (Na 2 CO 3 ioH 2 O) by efflorescence loses 9 out of its 10 molecules of water and becomes reduced to the carbonate of sodium (of different crystalline form) represented by the formula NagCO^H^O. EGGS are nutritious articles of food. The shell of birds' eggs consists for the most part of calcium carbonate (about 90 per cent.), calcium and magnesium phosphates (about 6 per cent.), and animal matter and sulphur (about 4 to 5 per cent.). The white of egg is albumin, whilst the yolk is of compli- cated composition containing fatty matters, lecithin (a phosphorized organic principle present in brain matter), cholesterine, etc. The eggs and roes of fishes are, for the most part, of somewhat similar composition and equally valuable as foods. Both the albumin and the yolks of eggs are used in many industries. ELAlDIC ACID A white crystalline stereoisomericformof oleic acid (C 18 H 34 O 2 ), obtained by the action of nitrous acid upon that substance at 200 C. in the presence of sulphurous acid or sodium bisulphite. It melts at 51 to 52 C. ELASTICITY Capability of being stretched and resumption of original shape and dimension upon cessation of the force used to alter the original form. ELECTRICAL PRECIPITATION OF GASES See Cottrell Precipitating Plant. ELECTRICITY (and Magnetism) Electricity, like heat and light, has in the past been generally regarded as a form of energy, often, if not always, produced as one of the results or accompaniments of chemical action. Indeed, it was at one time chiefly produced by chemical means, using what are called voltaic batteries specially constructed for the purpose. Sir Joseph Thomson is supposed to have proved that the agency we call negative electricity is atomic in structure, and exists in indivisible units now named electrons, carry- ing a certain electric charge, having a certain mass, as constituents of all chemical atoms. An electrically neutral atom which has lost one or more electrons is called a positive ion, and neutral atoms which have lost or gained electrons are said to be ionized. A stick of sealing-wax, a glass rod, or a piece of amber rubbed briskly upon the coat sleeve becomes electrified, and in this state can be made to pick up bits of paper. ELECTRICITY 163 ELECTRICITY (Continued) There are machines which produce electricity by friction, as, for example, when a plate of glass is made to revolve rapidly between two cushions of cloth. An appliance of this kind can be constructed in connection with metallic parts in such a way that the electricity con- ducted to a point and discharged therefrom in the form of sparks is strong enough to knock a man down. Lightning is a discharge of electricity (as revealed to the senses by accompanying light and sound) from clouds charged with it; and just as heat can be conducted by metals, so can electricity. It is for this reason that so-called lightning conductors are attached to tall buildings and chimney-shafts to protect them against destruction. These lightning conductors are generally made of copper with pointed ends, and they attract and conduct the electric force into the earth or water with which they are connected at the lower end. If two plates or rods, one of metallic zinc and the other of metallic copper, be placed in a glass jar containing dilute hydrochloric acid and allowed to touch each other or be connected by, say, a piece of copper wire, a chemical inter- action is seen to take place. The zinc is attacked by the acid, although the copper appears to be unaffected ; the acid is decomposed and hydrogen gas is given off from the surface of the copper, the zinc having a greater attraction for the chlorine of the hydrochloric acid than the copper. The explanation, so far as it is understood, is complicated ; but it may be said that the two metals assume opposite electric states : a current of electricity flows away from the zinc and carries the hydrogen gas to the copper from the surface of which it is discharged. The copper is called the positive pole or anode, and the zinc the negative pole or cathode, and, to prove that a current of electricity is really passing from one to the other, it is only necessary, instead of allowing the two plates to touch each other, to connect the two metals under these circumstances with a fine thread of platinum wire instead of one of copper, when because it is not such a good conductor of electricity, and therefore offers more resistance to its passage it becomes red-hot, showing that the electric discharge, being impeded or obstructed, is transformed to some extent into heat. Again, if a strip each of zinc and platinum be dipped in a vessel containing dilute sulphuric acid, little action takes place so long as the two metals do not touch each other ; 1 64 ELECTRIC BATTERIES ELECTRICITY (Continued) but if they be joined together with, say, a copper wire, the zinc commences to dissolve and hydrogen gas is given off from the surface of the platinum strip, although that metal itself is entirely unaffected by the acid. Meanwhile an electric current passes through the wire, and continues to do so, as long as the action of the acid upon the zinc goes on. This is another instance of chemical change producing electric energy, and such an arrangement is styled a galvanic or voltaic element. The wasting of the zinc furnishes the energy, and the quantity of electricity that passes is pro- portional to the amount of chemical action, which is repre- sented by the equation Zn + H 2 SO 4 = ZnSO 4 + H 2 . A battery consists of a number of such elements or cells grouped up together. In this case, the zinc plate, or ter- minal wire connected with it, is again the negative pole of the battery, and that of the platinum plate from which the electric current starts on its circuit back to the zinc is the positive pole. In the Grove battery, which is often used in chemical laboratories, the outer cell (made of glass or ebonite) is charged^ with dilute sulphuric acid (1:7) and a zinc plate Grove Battery. (the surface of which is amalgamated with mercury to moderate the action of the acid on the zinc) ; while in the inner, or porous cell, a thin sheet of platinum, immersed in strong nitric acid, serves as the negative pole. The zinc being attacked by the sulphuric acid liberates hydrogen, which in passing through the nitric acid decomposes it, producing water and nitric peroxide (N 2 O 4 ) gas. ELECTROLYSIS 165 Bunsen Cell. ELECTRICITY (Continued) The next illustration is of a cylindrical cell of Bunsen's carbon battery, consisting of an oblong prism of carbon, a zinc cylinder, a porous pot, glass cell, and binding clamp. In this modification of Grove's battery, the carbon replaces the platinum sheet, and is connected with the zinc of the next cell by means of a copper strip. A third form, which finds more general use and is of special service for working elec- tric bells and telephones, is the Leclanche battery. In this, zinc- carbon cells are employed ; that is to say, each cell consists of a glass vessel in which are placed a block or plate of carbon (char- coal) and a block or rod of metallic zinc, immersed in a solution of sal ammoniac (am- monium chloride, NH 4 C1) dis- solved in water. On connecting the carbon and zinc parts with wire, the cells become active and an electric current is generated. The zinc, in dissolving, forms a double chloride of zinc and ammonium, and ammonia gas and hydrogen are liberated at the carbon pole. To prevent so-called polarization that is, interference caused by the accumulation of a layer of bubbles of gas on the carbon pole (which would interfere with the satisfactory working of the battery) the carbon block or plate is packed inside a porous pot with fragments of carbon and powdered man- ganese dioxide (MnO 2 ). There is reason for believing that thermo-electric currents occur in a single homogeneous metal such, for example, as mercury and not merely where two distinct metals are present. An electric current is capable of breaking up or decom- posing many chemical substances when in a state of solu- tion, and this process is described as electrolysis. For example, a moderately strong solution of hydrochloric acid (HC1) is resolved in this way into hydrogen gas, which is given off at one pole, and chlorine gas, which is evolved at the other pole. Water can similarly be broken up into its constituent parts, and the resulting elements are always produced in their equivalent proportions i part of 166 ELECTRICITY AND MAGNETISM ELECTRICITY (Continued) hydrogen, for example, being accompanied by 35^ parts of chlorine when hydrochloric acid solution is decomposed as above referred to. In the electrolysis of cupric sulphate solution, the positively charged copper ions or electrons are deposited on the cathode, and are termed cathions, while the SO 4 ions, which move to the anode and are negatively charged, are termed anions. It is these charges of elec- tricity which differentiates ions from the free elements. (See Voltameter.) The electric current which is generated by chemical or galvanic batteries can be conducted or carried away by metallic wires or rods in the form of a current and utilized as such, or can be transformed into heat, as in electric radiators, or into power by means of electric motors. The art of electro-plating of metals is dependent upon the deposition of metals from solution on other metals, as effected by the electrolysis of metallic solutions. In silver- plating, for example, the articles to be plated are hung in the solution of a silver salt, and plates of pure silver are also placed in the same liquid, a current of electricity being passed in through the silver plates and out from the iron or other articles to be plated. In this way the pure silver is gradually dissolved, and that metal is deposited as a coating on the spoons, forks, or other articles which it is desired to plate. As opposed to metals which are good conductors of electricity, other substances show a resistance or incapability of conduction, and such non-conducting materials are used in the construction of so-called insulators ; for example, the porcelain blocks or cups that are used on telegraph-posts for carrying the electric* wires, so that the current is not wasted by being carried or conducted away from the wires ; and for the same reason telegraph cables are covered with gutta-percha, which is non-conducting. Magnetism is of the same essential nature as electricity, and the mineral known as loadstone (magnetic oxide of iron) possesses the power of attracting iron as a natural property. Steel is easily magnetized by contact with another magnet, and it then has the property of attracting or drawing towards its poles a needle or piece of iron placed near to it. Nickel and cobalt are also magnetic. Magnetism acts not only at a distance, but also through paper or silk or glass; that is to say, if a needle be placed on a thin sheet of paper or glass, a magnet moved about under the paper or glass attracts and draws ELECTRICITY AND DYNAMOS 167 ELECTRICITY (Continued) the needle in whichever direction it moves. The whole earth acts as a magnet, and its magnetic poles, although not identical with the geographical poles, are in their near neighbourhood. Consequently the mariner's compass, being a magnetized needle and placed upon a pivot, always points one end to the north and the other to the south. The ease with which iron or steel can be magnetized by electricity is utilized, as we shall presently show, in the construction of electro-magnetic machines. Electric currents are known to exist in the muscles and nerves of animal structures, and are doubtless connected with the chemical changes that are constantly taking place in living bodies. Cats emit electricity, and in dry frosty weather, little sparks can be seen to pass from the standing fur of their coats to the hand when used for stroking them. Several water-animals produce electric discharges, and in particular may be mentioned the Raid torpedo (or electric ray), found in the Mediterranean and Atlantic, which possesses an electric organ on the back of its head ; whilst the Gymnotus electricus (or Surinam eel) has an electric organ running along the whole length of its body, and is capable of giving a terrible shock. The discovery by Faraday that currents of electricity can be induced in a conductor by moving it between the two poles of a magnet has, in course of time, led to the construction of the magneto-electric machines known as dynamos or electric generators and electric motors, both of which appliances are now extensively used for many com- mercial purposes. Dynamos have, of course, supplanted the use of voltaic batteries in all cases where large applications of electricity are required. Dynamo-electric machines produce electricity by the rapid rotation of an armature made of iron and wound round with coils of insulated wire, between (but not touching) the two poles of a fixed magnet round which are also wound coils of insulated wire, it having been found that the magnetism and consequent electric current is intensified by this wrapping of wire. The rotation of the armature, as it is called, can be effected by using the power of waterfalls, or steam, gas, and oil engines. The current of electricity thus generated flows alternately in opposite directions as the coils pass the two poles of the fixed magnet ; but a device called the commutator (placed 168 ELECTRICITY ELECTRICITY (Continued) on the same shaft as that which carries the armature) has collecting brushes attached to it, and these gather up and cause the current to flow in one and the same direction. The electric motor is constructed on the same general principle, but in this case the electric current is used to cause the rotation of the armature, which in its turn is employed as a propellant for the machinery with which it may be connected, and in this way the electricity em- ployed is converted into mechanical power. The electric telegraph enables the user to transmit signals by means of an electric current to distant places, the move- ments or sounds made at one end of the wire being repro- duced at the other end. These movements or sounds are interpreted by an understood code, and in some cases the messages are printed in type or ordinary letters. The telephone is another electric contrivance by means of which an electric current passing through or along a wire reproduces at the far end, or receiver, movements corre- sponding to those produced in the transmitter by the sound waves of the voice. Electric lights are of two classes viz., the arc light and the incandescent light. In the former, the electric current passes from an upper rod of carbon to a lower one across the space which is maintained between them, producing a cloud of carbon vapour which, being intensely heated, forms a luminous arc of flame or light. In incandescent lamps, on the other hand, the filament or thread of carbon or metal which is made luminous, is contained within a glass vessel from which the air has been removed. If these lamps were not exhausted of air, carbon threads would be destroyed by burning that is, by combination of the carbon with the oxygen contained in the air. As it is, the current flows in at one end of the filament and out at the other and heats it to a state of incandescence. In other words, so much of the electric current is transformed into heat and light in consequence of the resistance offered to its passage. To a very large extent, carbon filaments are no longer used, metallic ones of various kinds having replaced them to great advantage. The so-called storage batteries do not really store up the electric current which is passed into them. The current used for charging them, effects certain chemical changes or decompositions in the contents of the storage cells, and these changes are of such a character that when ELECTRICITY ELECTROLYSIS 169 ELECTRICITY (Continued) the electric current is shut off, the storage cells act as voltaic batteries in consequence of further new chemical changes that then take place. In other words, when they are used, they run down or undo the changes effected by the electric charge and restore the elements of these cells to their original condition, thus preparing them ready to receive a further charge of electricity. Electrolytic methods are now largely used in the manu- facture of various chemicals, being employed, for example, in the preparation of the metals sodium, magnesium, calcium, and aluminium by the electrolysis of fused com- pounds of these metals ; also for refining copper, silver, and gold ; the extraction of some metals from their solu- tions, the manufacture of soda, and the preparation of hydrogen and oxygen gases. The introduction of the dynamo has also led to the con- struction of electrical furnaces, one of which, constructed on the principle of the arc light, exhibits a temperature of from about 3,000 to 3,500 C. They are used amongst other applications for the production of carborundum, graphite, artificial sapphires, rubies, calcium carbide (CaC 2 ), silicon, fused silica ware for chemical use, the utilization of steel turnings, the remelting of nickel-chrome steel, the preparation of ferro-alloys, etc. Electric furnaces, in which the heating element consists of a metallic wire or strip, are now widely used in labora- tories and workshops, and there are a variety of specially constructed ones made on the " muffle " and other prin- ciples. ELECTRIC BATTERIES } FURNACE LAMPS LIGHT MOTORS RADIATORS TELEGRAPH TELEPHONE See Electricity. ELECTRODES The poles of an electric battery or the terminals carrying an electric current into and out from a liquid. ELECTROLYSIS Decomposition of fluids by the agency of the electric or voltaic current. i;o ELECTROLYTE ELEMENTS ELECTROLYTE A substance admitting of being broken up by electrolysis. ELECTRO-GILDING See Gold. ELECTRO-PLATING See Electricity. ELECTRONS Hypothetical conceptions of ultra-atomic par- ticles or corpuscles, carrying a negative charge of elec- tricity, this charge being the smallest known ; it being further supposed that every quantity of electricity is a multiple of this elementary charge, and that these electrons are incomparably smaller than atoms. The mass of the electron is said to be 1,830 times smaller than the atom of hydrogen, which is the lightest known ; but from a chemical point of view, electrons must be constituent parts of atomic matter. The number of electrons in an atom is stated to be approximately half its atomic weight. The term is used more generally to characterize the extremely minute particles shot off in electric discharges in gases, as well as the emissions from helium, argon, and other radio- active substances. (See Atoms, Cathode Rays, Rontgen Rays, and Radio-activity.) ELEMENTS The various forms of matter of which all chemical combinations are composed. They are only to be regarded as elemental in the sense that they cannot be easily decomposed or split up into two or more distinct substances. Gold is an example, and from it substantially nothing but gold can be obtained, as distinct from a com- pound body like water which can be decomposed into hydrogen and oxygen. It is, however, conceivable, and believed by many, that all the elements are really compounded of one primordial matter (protyle), and only vary in character according to the physical conditions under which they exist and are recognized. Eighty-three or more of these entities are known, and there are probably more yet undiscovered. Most of these entities are metallic in character, but the non-metallic ones exist more abundantly in nature, and in- clude oxygen, silicon, hydrogen, nitrogen, carbon, chlorine, bromine, fluorine, and iodine. The two classes of metallic and non-metallic bodies gradually merge into one another, the intermediate class being sometimes described as metalloids arsenic, for example. In the abbreviated table given on p. 172 the metallic ones are marked with m, while those marked g exist ordin- arily in the gaseous form. A more complete list of the chemical elements will be found on p. 44, and all (and ELEMENTS 171 ELEMENTS (Continued) some of their compounds) are described under their several names. The symbols used to represent the chemical elements are for the most part abbreviations of their common names ; thus, the symbol of hydrogen is H, that of nitrogen N, that of calcium Ca ; but there are exceptions, and while it is a pity that the symbols of these exceptional instances are still used, it will be useful to explain the reason. The metal antimony has the symbol Sb because the Latin name for antimony is stibium. The metal lead has the symbol Pb, the Latin name for lead being plumbum. The metal mercury is indicated by the letters Hg, as the Latin name for it is hydrargyrum. Potassium is symbolized by the letter K, its Latin name being kalium. Sodium is symbolized by Na because natrium is its Latin name. The metal tin has the symbol Sn, from the Latin name st annum. The metal gold is marked Au, from the Latin name aurum. The metal iron is marked Fe, from the Latin nameferrum. The metal silver is marked Ag, from the Latin name argentum. The metal copper is marked Cu, from the Latin name cuprum. The chemical constitution of compounds is represented by so-called formula or combinations of letters or symbols ; thus, the formula of common salt (sodium chloride) is NaCl, that of water H 2 O, and so forth. (See Formulas.) Classification of the Elements The chief elements can, to some extent at least, be classified into natural groups in respect of their resemblances viz., as follows : 1 . A Ikali metals, including potassium, sodium, and lithium. 2. So-called alkaline - earth metals, including barium, strontium, calcium, and magnesium. 3. Halogens, including chlorine, bromine, iodine, and fluorine. 4. A larger group may be defined as more definitely metallic than those referred to in classes i and 2, and in- clude aluminium, antimony, bismuth, cadmium, chromium, cobalt, copper, gold, iron, lead, magnesium, manganese, mercury, nickel, platinum, silver, tin, vanadium, and zinc. 5. Those which are better known in their gaseous state are : hydrogen, chlorine, fluorine, oxygen, nitrogen, and argon. 172 ELEMENTS AND THEIR SYMBOLS ELEMENTS (Continued) 6. The non-metals include all the elements in classes 3 and 5, also boron, sulphur, carbon, phosphorus, and silicon. Carbon is peculiar as being the one essential element of all so-called organic compounds, whilst silicon is one of the most abundant elements found in nature. Apart from the carbonates of the metals, most of the other compounds con- taining carbon are known as organic compounds, and, indeed, organic chemistry is sometimes defined as the chemistry of carbon and its compounds. These compounds are more numerous than those of all the other elements, and so far as they are constituents of animal and vegetable tissues, they are of more complicated constitution than most other chemical compounds : besides oxygen and hydrogen, they not infrequently include nitrogen, sulphur, and phosphorus as constituents. Better Known Elements LlST, WITH THEIR SYMBOLS AND GENERALLY ACCEPTED ATOMIC WEIGHTS, HYDROGEN (i) BEING TAKEN AS THE STANDARD. Name. Symbol. Atomic Weight. Name. Symbol Atomic Weight. m Aluminium Al 27 m Magnesium Mg 24 m Antimony Sb 120 m Manganese Mn 55 m Arsenic As 75 m Mercury Hg 200 m Barium Ba 137 m Nickel Ni 59 m Bismuth Bi 208 g Nitrogen N 14 Boron B ii g Oxygen 16 Bromine Br 80 Phosphorus P 3i m Cadmium Cd 112 m Platinum Pt 195 m Calcium Ca 40 m Potassium K 39 Carbon C .12 m Radium Ra 226-4 g Chlorine Cl 35*5 Silicon Si 28 m Chromium Cr 5 2 m Silver 1 Ag 108 m Cobalt Co 59 m Sodium Na 23 m Copper Cu 63-5 m Strontium Sr 87-6 g Fluorine Fl 19 Sulphur S 32 wGold Au 197 m Thorium Th 232 g Hydrogen H i m Tin Sn 118 Iodine I 127 m Uranium U 238-5 m Iron Fe 56 m Vanadium V 5i m Lead Pb 207 m Zinc Zn 65 m Lithium Li 7 ELEMENTS PERIODIC LAW i?3 ELEMENTS (Continued) Periodic Law Many of the chemical elements that re- semble one another in their properties appear also to exhibit certain numerical relations for example, lithium, sodium, and potassium having the atomic weights of 7, 23, and 39 exhibit an average number 23 by the addition of the two extreme numbers, 7 and 39, and dividing by 2, this average being that of the atomic weight of sodium. These numerical relations and the gradation in the properties of the elements have led up to what is known as the periodic law, the basic idea being that the chemically analogous elements constitute families, the members of which recur after regular intervals when arranged in order of their atomic weights. It may be broadly expressed by the statement that the properties of the elements and their compounds constitute a periodic function of the elemental atomic weights. These functions are noticeable, fpr example, in their electrical characters, the ductility, malleability, and melting-points of the metals, and in their so-called atomic volumes. The full meaning of these relations is not yet clear, but as a working hypothesis the periodic law has proved of much service, and further investigations will, without doubt, clear up much that is at present not under- standable regarding the constitution of the entities of matter as presented in the various so-called elements and their multitudinous compounds. If the atomic weights of two elements be divided by their respective specific gravities the quotients give the relative volumes occupied by their respective single atoms, and Hawksworth Collins concludes from this and other considerations that " the relative volumes of the elements are the fundamental constants of nature." Evidence has been adduced to indicate that cohesiveness as well as chemical affinity, exerts pressure in its action and plays a part in determining the volumes occupied by molecules. Richards has pointed out that the compressibilities of the solid elements as determined by him at Harvard University seem to be, like the atomic volumes, periodic functions of the atomic weights. As to the transmutation of the elements it has been con- jectured that the following cases may possibly be factual : Radium Helium = Niton (226 atomic weight) (4) (222) 4 Hydrogen = Helium (4) (4) 174 ELEMENTS CHEMICAL ENTITIES ELEMENTS (Continued) 4 Hydrogen + Oxygen =Neon (4) (16) (20) Sulphur + 8 Hydrogen = Argon (32) (8) (40) Selenium + 4 Hydrogen = Krypton (79) (4) (83) (Compare Radio-activity, Electrons, Radium, and Atoms. ) A modified (isotypic) form of metallic lead can be apparently derived from uranium through ionium and radium as intervening atomic matters, although this calls for definite confirmation. (See Lead.) The origination of helium from uranium and thorium- bearing minerals; its production from radium and niton established qualitatively and quantitatively ; and lastly its synthesis by subjecting hydrogen to the action of the cathode "rays and its combination with oxygen to produce neon : all these circumstances seem to demonstrate trans- mutations of the chemical elements and the common basic nature of ultimate matter. According to Dr. Aston, who has employed a method of so-called "mass spectra" (that is, spectra obtained on a photographic plate placed in vacuo, by deflecting positive rays on to it by passing them first through an electric and then through a magnetic field in such a way that all the rays corresponding to an element of given mass are con- centrated in a short line, on the plate and those of different masses in other parallel lines), it has been demonstrated that boron consists of two, neon, silicon, and chlorine of two or three, bromine of two, krypton of six, and mercury of at least two isotypes that is, elements of the same chemical properties but of different atomic weights. (See Isotypes.) Some writers on this particular subject regard it as proved that all the elements are polymers of hydrogen. In view, however, of recent investigations concerning atomic struc- ture, radio-activity, and the facts above and elsewhere referred to, it appears hardly correct to write any longer of chemical elements, but to regard them merely as more or less stable chemical entities, recognizable by their physical and chemical characteristics under particular circumstances, but susceptible of an indefinite number of changes capable of being brought about by the disturbing influence of applied force. There is an interdependence of matter and force, and just as the manifestations of heat, light, and ELEMENTS EMULSION 175 ELEMENTS (Continued) electricity cannot be made without the employment of chemical entities, so also these chemical entities depend for their characteristics and changes upon force : no matter without force, no force without matter. In other words, chemical substances may be regarded as symmetrical arrangements of matter. (See Electrons.) ELEMI See Gums. ELUTRIATION Separation of the lighter from the heavier, or smaller from the larger particles of powders by washing and decantation by means of an appliance known as an " elutriator " as used in the preparation of ground barytes for making paint. EMBOLITE A mineral chloro-bromide of silver found in Arizona, Colorado, New Mexico, and Chile, having the composition Ag 5 Cl 3 Br 2 or Ag(ClBr). EMERALD A double silicate of aluminium and glucinum, or green variety of beryl, being a gem found in mineral form. EMERALD GREEN A pigment, being a combination of metar- senite and acetate of copper (3Cu(AsO 2 ) 2 ,(Cu)C 2 H 3 O 2 ) 2 ). EMERY A native form of alumina coloured with oxides of iron and manganese (corundum) ; used as an abrasive that is, for grinding and polishing by reason of its hardness. EMETINE A mixture of alkaloids extracted from the root of Cephaelis ipecacuanha, which, as also their hydrochlorides, is largely used in medicine and dentistry. EMULSIN (Synaptase) An enzyme being a constituent of bitter almonds capable of hydrolyzing most of the natural glucosides. (See Amygdalin and Glucosides.) EMULSION A mechanical admixture of fluids that will not naturally mix together, such as oil and water. Emulsions are apt to separate more or less into layers on standing. Some are prepared by the use of gum or resin in a state of solution which has the property of holding in suspension the oily particles of other liquids shaken up therewith ; others are prepared with milk, the yolk of eggs, soap, or mucilage. Emulsions are, for the most part, milky in appearance, but there are other emulsions which, though quite transparent and uniform in character, are not to be regarded as true solutions. Emulsions have been recently described as " model sus- pension colloids," and again as " heterogeneous systems" in i?6 EMULSION ENFLE URA GE EMULSION (Continued) which a liquid is dispersed as droplets in some other liquid with which it is only partially or not at all miscible. An emulsion of oil in water is produced if the emulsifying agent is a colloid soluble in water or more easily wetted by water than oil, and an emulsion of water in oil is obtained when the emulsifying agent is an oil-soluble colloid or is more easily wetted by oil than by water. ENAMELS are fusible glasses rendered opaque by dissemination throughout the mass of a vitreous substance infusible at the temperature at which they are made, such as oxide of tin. Up to about 900 C. the tin dioxide exists in a state of suspension in the enamel, but if that temperature be exceeded, real solution takes place and the opacity is diminished. Titanic oxide, zirconia, and other vitreous substances can be employed in place of the stannic oxide. The opacity is due to the difference in refractive index, and is obtained in some cases by the use of arsenious oxide, calcium phosphate, cryolite, etc. Platinum and iridium oxide are sometimes used to produce greys in enamels, and a great variety of other substances can be used according to the desired tint and other characteristics. One kind of enamel used for glazing cast-iron articles, such as saucepans, consists of powdered flints ground together with calcined borax, fire-clay, and a little felspar, made into a paste and applied to the surfaces, which are then dusted over with a glaze-mixture composed of felspar, soda-ash, borax, and a little oxide of tin, after which they are dried and fired at a red heat. ENAMELLED IRON Iron plates are enamelled by coating them, after cleaning, with alkaline silicates containing borates, and then firing them. ENAMEL PAINTS Paints ready mixed with varnish so that they dry with an enamelled face or gloss. (See Paints.) ENDOSMOSE The passage by diffusion through a separating membrane such as bladder, of two solutions (one within the bladder and one without in a containing vessel) from the one into the other mutually. (See Dialysis and Osmosis.) ENDOTHERMIC COMPOUNDS See Heat. ENERGY The power of doing work. (See Force.) ENFLEURAGE See Perfumes, ENZYMES 177 ENZYMES A class of non-organized colloidal nitrogenous substances produced by and associated with certain living animal and vegetable tissues, capable of initiating changes in many chemical substances in the nature of fermentation, hydrolysis, and oxidation, but none of which have been isolated in a pure state, their existence being recognized by their actions in solution. Ptyalin, the active ferment of saliva, for instance, converts the starch of food into sugar. The alcoholic fermentation of sugar is due to the enzyme named zymase, as produced by yeast cells. (See Fermen- tation.) For the most part, they seem to act as catalysts by way of hydrolysis ; one such change, for example, being the conversion of cane-sugar into glucose and fructose by invertase, brought about by the assimilation of water C 12 H 22 O n + H 2 = C 6 H 12 6 + C 6 H 12 6 , and another such change being the hydrolysis of starch by means of amylopsin or pancreatic diastase into maltose and dextrin, and by a further change these two saccharoid bodies are converted into alcohol Starch is similarly converted by diastase into maltose (C 12 H 22 O n +H 2 O) (malt sugar), and dextrin is converted by the enzyme diastase contained in germinated barley. Emulsin probably contains several distinct enzymes. The digestive enzymes comprise many hydrolytic agents capable of replacing the - NH 2 group by the - OH group, as in the case of urea. Trypsin, one of the pancreatic enzymes, is most active in the presence of alkalies, and decomposes many albu- minous bodies down to the stage of polypeptides, whilst papain (papayotin), which occurs in the melon-tree (Cavica papaya L.), is a similar enzyme of vegetable origin. Pepsin, on the other hand, acts only in acid solutions, and while it does not hydrolyze any known polypeptide it converts albumins into a number of derived compounds viz., the so-called anti- and hemi-albumoses, but does not proceed so far in its action as to produce simple amino -acids. It has been shown, however, that pancreatin and trypsin can carry the stage of hydrolysis of albumoses farther, thus converting anti-albumose into peptone and hemi- albumose into leucine, tyrosine, aspartic acid and glutamic acid, these last-named substances being members of the amino-acid group. (See Amino acids and Proteins.) 12 i;8 ENZYMES ENZYMES (Continued) Yet another class of enzymes, styled desamidases, are stated to be capable of splitting up the amino-acids into ammonia and hydroxy-acids. Lipase, an enzyme associated with trypsin, has the power of breaking up fats into glycerol and fatty acids. There are certain enzymes occurring in all parts of plants and animals named oxidases, or ptroxidases, which are concerned in acts of oxidation, as, for example, in the process of respiration. Another enzyme, styled aldehydase, said to be contained in the liver, lung, and spleen, is credited with the capability of converting aldehydes into the corresponding acids. The coagulase class of enzymes can institute changes in various liquids, resulting in the formation of insoluble substances ; thus, rennet (chymase) forms curd in milk ; thrombose is concerned in the coagulation of blood, and pectase in the production of insoluble pectic acids from the pectin substance of plants. The particular enzymes associated with bacterial life are necessarily many in number, and must vary in their chemical actions, not merely with the kind of bacteria, but more particularly with the media in which they are allowed to develop, so that their entire range of action must be enormous and extremely varied in character. In their action as catalysts, the rate is proportional to the strength of the enzymes, although the total changes which they institute are independent of the amount, given sufficient time, and always provided the enzymes are not destroyed. Their activity is wholly destroyed when heated to 100 C., while rennet, thrombin, pepsin, and diastase are inactivated at 45 C. As to the mechanism of enzyme action, it is generally held that adsorption compounds (see Adsorption) are formed between the enzyme and the substrate that is, the sub- stance which is decomposed and that it is these com- pounds which react with water ; but the whole subject calls for much further investigation before it can be fully understood and explained. The action of enzymes is often assisted or promoted by associated substances styled activators, and, on the other hand, it is often interfered with or arrested by other sub- stances classed as paralyzers, or poisons (like sulphur), the latter behaving, in this sense, as antiseptics do in respect of bacterial processes of decomposition. (See also Catalytic, Emulsin, Oxydases, and Vitamines.) EOSINERBIUM 179 EOSIN (C 20 H 8 Br 4 O 5 ) A red, crystalline dye, soluble in alcohol and acetic acid, prepared by the bromination of fluorescein ; it is used for dyeing silk, cotton, and wool ; also for making a red ink. The potassium salt, C 20 H 6 Br 4 O 5 K 2 , is also known commercially as eosin, and used for the same purposes. " EPHOS " A basic phosphate made from an Egyptian source, containing from 60 to 65 per cent, of tricalcium phosphate, of which 85 to 95 per cent, is soluble in 0-2 per cent, solution of citric acid. " EPONITE "A decolourizing char in the nature of a vege- table soot, containing about 82 per cent, of carbon, the decolourizing efficiency of which is increased, according to C. F. Bardos, by addition of 30 to 50 per cent, of charred sawdust. (See " Karbos.") EPSOM SALTS Magnesium sulphate (MgSO 4 ,7H 2 O). EQUATIONS See Chemical Interactions. EQUIVALENTS Otherwise described as "equivalent weights" or " combining proportions," represent the proportions by weight in which the chemical elements combine amongst themselves ; or, in other words, the weights which will combine with i part of hydrogen. In many cases, these equivalent weights are identical with the atomic weights of the same elements, but not in all cases. For instance, the affinity of oxygen for hydrogen requires 2 atoms for its saturation to produce water (H 2 O), and as the relative weight of hydrogen as the standard is i, that of oxygen is 8. Sulphur also requires 2 atoms of hydrogen to satisfy its affinity, and whilst its atomic weight is 32, its equivalent weight is therefore 16. Phosphorus and arsenic require each 3 atoms of hydrogen, and this varying power of com- bination of each element is termed its valency. (See Chemical Compounds and Valencies.) ERBIUM (Er) Atomic weight, 167-7. A rare element belong- ing to the so-called yttrium group, and occurring in nature in the minerals gadolinite, yttvotantalite, euxenite, etc., together with the earth yttria. Its oxide erbia (Er 2 O 3 ) is obtained by heating the nitrate or precipitated hydrate, and is yellow in colour, while its salts, including the chloride (ErCl 3 ), nitrate (Er(NO 3 ) 3 5H 2 O), bromide (ErBr 3 ,9H 2 O), chlorate (Er(ClO 3 ) 3 ,8H 2 O), bromate (Er(BrO 3 ) 3 ), and sulphate (Er 2 (SO 4 ) 3 ,8H 2 O), etc., are crystalline in character, of a rosy tint, and are soluble in water. The oxide can be also prepared by heating the oxalate at 575 to 845 C. i8o EREMACAUSIS ESSENTIAL OILS EREMACAUSIS The slow combustion or consumption by oxidation and other changes as evidenced in nature by the decay of timber, the heating of grain or grass, the decom- position of vegetable matter generally, etc. Low forms of life have much to do with the initiation of the process, which is stopped by perfect dryness and by a temperature below freezing-point. (See Dry-rot.) ERGOT OF RYE A fungoid growth on the seeds of the com- mon rye, containing an active principle named ergotine, in the nature of a yellow crystalline alkaloid soluble in alcohol and ether, which possesses narcotic properties, and is used in medicine. The formula C 35 H 40 N 4 O 6 is sometimes assigned to it. ERLENMEYER FLASK See Flasks. ERYTHRITE (Cobalt Bloom) See Cobalt. ERYTHROSIN A well-known dye, allied in constitution to eosin. ESERINE SULPHATE An alkaloidal salt made from the Calabar bean or seed of Physostigma venenosum of West Africa. ESPARTO GRASS (Alva) A strong tufty wild grass (Stipa tenacissima) which grows abundantly in Spain and Algeria, and is largely used in the manufacture of cordage and paper. It is boiled with caustic soda to dissolve the fleshy parts, then bleached. A wax, amounting to 3^ per cent., is obtained as a by-product. The trade is very large, amounting to more than 200,000 tons per annum. ESSENCES Another name for essential oils. ESSENTIAL OILS are the volatile oils or essences formed naturally in various trees and plants, such as oil of turpen- tine (pine-trees), eucalyptus oil (eilcalyptus-trees), camphor oil (camphor-trees), etc. Many of them, including those already named, are in the main hydrocarbons, and are characterized by their various constituent terpenes, which are isomeric bodies having the general chemical formula C 10 H 16 . Others contain in addition oxidized substances of the nature of alcohols or ketones and some small quantities of sulphur or nitrogen. Pine and fir trees are widely distributed in nature, and the turpentine oil which they yield is by no means uniform in constitution. Russian, American, German, Venetian, Swiss, Swedish, French, and Indian oils all differ in the nature or proportions of the various terpenes contained in them and their other constituents. ESSENTIAL OILS 181 ESSENTIAL OILS (Continued) The essential oils have characteristic odours and are all inflammable, insoluble in water, but soluble in alcohol and in ether. Many are more or less susceptible to oxidation when exposed to the air or oxygen gas, thus forming oxidized products of a resinous nature and at the same time always giving rise in the presence of water (whenever they contain any terpenes) to the formation of hydrogen dioxide : ozone is not produced. The following is a list of some of the better known essential oils, showing the nature of their chief constituents : American turpentine oil, containing dextro-pinene (C 10 H 16 , aterpene). French ,, ,, ,, laevo-pinene (C 10 H ]6 , a terpene). Russian ,, ,, ,, sylvestrene (C 10 H ]6 , a terpene). Camphor oil ,, camphor (C 10 H 16 O, a ketone and a terpene). Eucalyptus oils ,, eucalyptol (an ether) and euca- lyptene and phillandrene (ter- penes). Orange oil ,, hesperidene and limonene (ter- penes). Lemon oil ,, limonene (a terpene) and citral (an aldehyde). Thyme oil ,, thymene (a terpene) and thymol (C 10 H 14 O, a phenol). Sandal wood oil ,, santene (a terpene). Citronella oil ,, geraniol (an alcohol). Peppermint oils ,, menthol (an alcohol). Spearmint oil ,, carvone (a ketone). Wintergreen oil , , methyl salicylate. Cinnamon oil ,, cinnamic aldehyde. In the umbeUifcrit, the essential oil is most abundant in the seeds ; in the aurantiacea, both fruits and flowers yield oil ; the rosacea contain oil only in the petals ; while the myvtacecB and the labiata yield most from the leaves. As further illustrating the immense variety of character of essential oils, it may be mentioned that there are more than 200 species of the eucalyptus, and all the oils vary in character. The better known ones are the amygdalina, globulus, oleosa, odorata, rcstata, dumosa, and citviodova oils. These oils are all produced by distillation of the parts of the trees con- taining them, whilst turpentine oil is produced as described elsewhere. The eucalyptus globulus oil has a sp. gr. of from 0*910 to 0*930, and contains as its principal con- stituent from 50 to 80 per cent, of a substance called eucalyptol, also known as cineol (C 10 H 18 O) a clear, colour- less liquid which can be frozen to a crystalline mass at - ito 3 C. Phellandrene is a terpene (C 10 H ]6 ) forming a large proportion of the amygdalina oil. i82 ESSENTIAL OILS ESTERS ESSENTIAL OILS (Continued) Many of the essential or ethereal oils are described under their individual names. (See also Balsams, Eucalyptus, Terpenes, and Turpentine.) ESTER GUMS Substitutes for the harder natural resins made by combining the acid resins with alcohols, such as glycerine. They are soluble in oil and turpentine, have acid values as low as from 2 to 20, and are stated to be much more suitable than ordinary resin for use in making varnishes and enamels. To prepare them, the softer parts of the resin are removed by distillation in a vacuum or a current of superheated steam, and the residue is heated with an equivalent proportion of glycerine, phenol, or naphthol, to a high temperature with a dehydrating agent. Resin esters can be formed with glycerine by heating together at from 280 to 300 C., and passing a current of hydrochloric acid gas, carbon dioxide, or air through the mixture. Ester gums are used in making enamel paints, and more particularly (in conjunction with china- wood oil) for water- proof varnishes for boats, yachts, etc. ESTERS Many alcohols react with acids, like metallic hydrox- ides and form what are termed alkyl salts or esters ; for example, ethyl alcohol and acetic acid by interaction give ethyl acetate and water C 2 H 6 OH + CH 3 CO,OH = CH 3 ,COO,C 2 H 5 + H 2 O, the replaceable hydrogen atoms of the carboxylic group (CO, OH) being exchanged for alkyl radicals, and the pro- cess is known as esterification. The esters so produced from the fatty acids are more or less volatile neutral liquids which are readily hydrolyzed when heated with water or alkalies or acids back again into the corresponding alcohols and acids. Monobasic acids such as nitric acid yield only one kind of ester termed " normal or neutral esters," but dibasic acids yield two series termed " acid esters " and " neutral esters " ; thus ethyl nitrate is (C 2 H 5 )NO 3 , while we have the two ethyl sulphates (C 2 H 5 ),HSO 4 and (C 2 H 5 ) 2 SO 4 .' The fats, palmitin, stearin, and olein are solid esters, or glyceryl esters of respectively palmitic, stearic, and oleic acids, and are resolved by hydrolysis into glycerol (glycerine) and the several fatty acids ; thus stearin ESTERS-MTHER 183 ESTERS (Continued] C 3 H 5 (C 18 H 35 O 2 ) 3 + 3KHO (potassium hydroxide) = 3K(C 18 H 35 O 2 ) (potassium stearate) + C 3 H 6 (OH) 3 (glycerine)- (See Fats and Soaps.) Some of the better known commercial esters are alpha- betically listed below : Amyl acetate Dimethyl sulphate benzoate Ethyl acetate borate aceto-acetate butyrate benzoate formate butyrate ,, valerianate formate salicylate salicylate Benzyl acetate Geranyl acetate ,, benzoate Glyceryl tri-acetate ,, chloride Methyl salicylate Butyl acetate Tricresyl phosphate ,, formate Triphenyl The amyl esters of formic, acetic, and hexoic (caproic) acids are among the odorous constituents of apples. (See also Ethers.) ETCHING See Fluorine. ETHANE or ETHYL HYDRIDE (C 2 H 6 ) A gaseous hydro- carbon constituent of crude petroleum. (See Hydrocarbons.) ETHER or .32THER (Medium) is a purely " hypothetical medium of great elasticity and extreme tenuity, supposed to pervade all space, the interior of solid bodies not ex- cepted, and to be the medium of transmission of light and heat " (Webster). Humboldt thought of the universe as filled with a world-ether or volatile fluid densified in the nebulae, more so in the comets (yet still penetrable by the rays of light) and in the planets as of all degrees of density from that of metals to that of honey, water, etc. Newton calculated upon slender data that imponderable ether must be at least 700,000 times less dense than air, basing this upon the velocity of the propagation of sound! as compared with that of light deduced from the horizontal parallax of the sun. To the chemical mind, it is inconceivable that the interstitial spaces of matter can be occupied by this hypothetical ether as, for example, an atmosphere of oxygen gas. So far as such a conception is possible, the result would be a mixture of oxygen and this so-called 1 84 ETHER ETHERS ETHER (Continued) ether, which, however imponderable, must have qualities and be detectable by them. Oliver Lodge has expressed the opinion that mechanical forces cannot be exercised across really empty space in the completest sense, but to the chemical mind there are no empty spaces, but only attenuated atmospheres. His reasoning appears to be paradoxical, for while he writes of matter and ether as distinct things, yet at other times he describes matter as essentially composed of this hypo- thetical ether. Chemically, then, the conception has no foundation, for if such a medium existed it could only be regarded as a universally distributed and extremely attenuated form of matter, and there is no evidence whatever of its material existence. (See also Porosity.) ETHEREAL Nature of ether ; light, volatile. ETHEREAL SALTS See Ethers (compound). ETHERS (or ALKYL-OXIDES) are a class of compounds which may be described as the anhydrides of the corresponding alcohols, as will be seen by comparison of the formulae here given : representing 2 molecules of ethyl alcohol from which a molecule of water is abstracted by the action of sulphuric acid at 140 C. The ethers, in other words, correspond in relation to the alcohols as metallic oxides to their hydrates C 2 H 6 HO ethyl alcohol, (C 2 H^) 2 O ethyl ether, NaHO sodium hydrate, Na 2 O sodium oxide. Ethyl Ether is also commonly known by the names of "sulphuric ether" and "vitriol ether," and is a mobile liquid of characteristic odour, soluble in alcohol, and very volatile and inflammable. When a mixture ;of ether vapour and air is allowed to expand suddenly into an evacuated tube it is found to ignite. It boils at 34*9 C., has a sp. gr. of 0*72, and is an excellent solvent of oils, fats, and many organic substances ; and, apart from its extensive use as an anaesthetic, it is used commercially in the colour industry and in the preparation of collodion, smokeless gunpowder, etc. Methyl Ether (CH 3 ) 2 O is a gaseous substance at ordinary temperatures, but liquefies at 20 C., and is prepared on ETHERS 185 ETHERS (Continued) a considerable scale for the production of artificial cold by its volatilization. ETHEES (Compound), or ethereal salts, correspond to metallic salts, and are formed by heating alcohols and acids together ; thus, for example, C 2 H 5 HO (ethyl alcohol) + C 2 H 4 O 2 (acetic acid) = C 2 H 5 ,C 2 H 3 O 2 (ethyl acetate) + H 2 O (water). They are for the most part volatile liquids, decomposed by acids and alkalies, but some of them are solid bodies, as, for example, the glycerides found in fats. (See Esters.) Acetic Ether (ethyl acetate) (C 2 H 5 .C 2 H 3 O 2 ) is a colour- less, fragrant, inflammable liquid of sp. gr. 0*9003, and boiling-point 77*15 C., soluble in water, alcohol, and ether. It is prepared by heating a mixture of ethyl alcohol, acetic acid, and sulphuric acid. Dissolved in alcohol it constitutes the so-called " essence of pears," and is ex- tensively used as a solvent, in perfumery, in medicine, and for flavouring. Benzole Ether (ethyl benzoate) (C 6 H 5 CO 2 C 2 H 5 ) A colourless, aromatic liquid of sp. gr. 1*0509 and boiling- point 212-9 C., soluble in alcohol and ether; prepared by heating ethyl alcohol and benzoic acid in presence of sulphuric acid ; used in perfumery and for flavouring ( u Essence of Niobe "). Butyric Ether (ethyl butyrate) (C 2 H 5 (C 4 H 7 O 2 )) is a colourless, volatile liquid of sp. gr. 0*8788, and boiling- point 120*6 C., soluble in alcohol and ether, constituting the so-called " essence of pine-apples," and is largely used for flavouring extracts. Capric Ether (ethyl caprate) (C 2 H 5 (C 10 H 19 O 2 ), of sp. gr. 0*87, and boiling-point 243 C., is used in making wine bouquet and cognac essence. Formic Ether (ethyl formate) (C 2 H 5 .HCO 2 ) is a mobile, colourless liquid, of peach-like odour; of sp. gr. 0*9231, and with a boiling-point of 54*05 C. It is used in manu- facturing artificially prepared rum and arrack, and other- wise for flavouring purposes. Nitric Ether (C 2 H 5 NO 3 ) is a colourless, inflammable liquid of pleasant odour, of sp. gr. 1-116 and boiling-point 87*6 C. It is soluble in alcohol, and is prepared by heating a mixture of alcohol, urea nitrate, and nitric acid, followed by distillation. i86 ETHYL ALCOHOL EUCALYPTUS OIL ETHYL ALCOHOL See Alcohols. ETHYL BENZOATE See Ethers (Benzole). ETHYL BROMIDE (C 2 H 5 Br) A liquid substitution product of ethane, of sp. gr. 1-468, soluble in alcohol and ether ; used as a local anaesthetic, and for the relief of migraine, asthma, and convulsions. ETHYL ETHER See Ethers. ETHYL NITRATE See Ethers (Nitric). ETHYL VALERIATE (C 2 H 5 (C 5 H 9 O 2 )) is a colourless liquid of pleasant odour, with a sp. gr. of 0-8765 and boiling- point 144*5 C-> use -d m compounding perfumes, etc. ETHYLAMINE See Amines. ETHYLENE See defines and Hydrocarbons. ETHYLENE CHLORIDE (CH 2 C1.CH 2 C1) An oily liquid anaes- thetic of sp. gr. .1-2823, soluble in water, alcohol and ether. EUCAINE (C 15 H 21 NO 2 ) A white, crystalline, organic com- pound used as a substitute for cocaine. EUCALYPTOL (Cineol) See Cineol and Essential Oils. EUCALYPTUS OIL This oil varies with the species (varying from very large trees to dwarf bushes), from which it is produced, and there are upwards of 200 species, so that the oils of commerce are often of mixed character and constitution, the several constituents (phellandrene, cineol, citral or geranial, pinene, and terpenes) varying accord- ingly in their proportions. They are all soluble in alcohol, ether, chloroform, and carbon disulphide, and are used in medicine, in perfumery, and some of them in the flotation process of ore concentration. The sp. gr. varies, for the reasons above given, from 0-850 to 0-940. The globulus variety is generally preferred to the amygdalina oil on account of its superior content of eucalyptol and its density of odour, but as sanitary agents there is little to choose between the many kinds of oil that are available. The globulus oil has a sp. gr. of from 0-91 to 0-93; refractive index, 1-469 to 1-475; rotation + 10 to - 10, and contains from 50 to 80 per cent, of cineol (C 10 H 18 O), which is soluble in alcohol. The Amygdalina Oil has a sp. gr. of 0-855 to 0-89, and a rotation of - 25 to - 8o- It is not nearly so pungent in odour as the globulus oil, and the terpene named phellandrene is its chief constituent EUCALYPTUS OILEUGENOL 187 EUCALYPTUS OIL (Continued) The Citriodora Oil has a sp. gr. of 0-87 to 0-905, and a rotation of -o to +2. It has a characteristic odour, does not contain cineol, but consists chiefly of citronellol. (See also Essential Oils.) EUCLASE A native silicate of aluminium and glucinum, otherwise known as prismatic emerald. EUDIOMETER A simple form of this apparatus, used for the examination of gases, is a long glass tube, closed at the one end and open at the other, graduated into cubic centi- metres by divisions etched on it. At the closed end, thin wires of platinum are fused into and through the glass, and thence pass outside, so that they can be connected with the wires of an electric coil. In using this apparatus to demon- strate the composition of water, a mixture of 2 volumes of hydrogen and i volume of oxygen is introduced into the tube, which is then inverted and placed with its open end in a trough of mercury. Upon now causing an electric spark to pass from end to end of the two wires within the tube, the two gases will combine with explosive force. In this way, it is found that 2 volumes of hydrogen and i volume of oxygen combine to form water, and if there be any excess of either gas contained in the mixture it will remain after the condensation that takes place in the eudiometer following upon the explosion. (See Volta- meter.) In laboratories where a mercury bath is available, this form of eudiometer may be used also to demonstrate the proportion of oxygen present in a given volume of air by inverting the graduated tube containing some air (the rest of the tube being occupied by mercury) over the bath, and introducing, by means of a pipette with a recurved end, some few cubic centimetres of a mixture of i part pyrogallic acid in 6 parts of water rendered alkaline by the addition of caustic potash solution. This solution rises up through the mercury in the tube, absorbs the oxygen of the air, becoming dark brown in colour in consequence, and leaves the nitrogen unabsorbed, the diminution in volume thus becoming apparent. EUGENOL See Cloves. i88 EUONYMIN EXOTHERMIC COMPOUNDS EUONYMIN An oleo-resinous body from the bark of the 'spindle-tree (Euonymus europaus), insoluble in water but soluble in alcohol, and said to have tonic and laxative properties; it is used medicinally in treatment of liver complaints. EUROPIUM (Eu) Atomic weight, 152. An exceedingly rare element belonging to the Terbium group, of which little is known, occurring in samarskite, orthite, cerite, and gadolinite, etc. " EUSOL " A proprietary antiseptic solution containing hypo- chlorous acid ; prepared by interaction between so-called chloride of lime and boric acid. EUTECTIC A term given to a solidified mixture of solute and solvent of the lowest melting-point ; for example, a molten mixture of zinc (which melts at 419 C.) and cad- mium (which melts at 321 C.) yields by solidification of one or other metal during cooling a eutectic mixture which contains 73 per cent, cadmium and solidifies at 270 C. EVAPORATION The passage from the liquid to the vaporous state, as when water is evaporated by the agency of heat into steam. Many liquids may be concentrated by means of evaporation, and for this purpose, chemists employ vessels termed evaporating basins or dishes. In this way the excess of water or other solvent which holds the chemical substance in solution is dissipated by evaporation. The process is also often conducted in a retort, so that the solvent, if valuable, can be condensed and recovered. Evaporation is retarded to some extent by salts and other soluble substances in solution, as compared with that of water. Evaporating basins are also often employed to obtain substances in a crystallized condition, or for drying solid masses or pasty mixtures by heating. They are made of various sizes, from 2 inches in diameter up to 12 inches or more, the larger ones being of porcelain, glass, and silica. Some smaller ones are made of silver, aluminium, platinum, and nickel (the choice being made according to the nature of the chemicals to be dealt with), and all are preferably provided with a lip to facilitate the transfer of their liquid contents to other vessels as and when required. EXHALATION The act of exhaling (breathing out) or passing out of vapours. EXOTHERMIC COMPOUNDS See Heat. EXPANSION EXPLOSIVES 189 EXPANSION The act of occupying a greater space. Gases, in particular, are easily expanded by heat. EXPLOSIVES Explosives are substances which, under the influence of heat or shock, or both, are instantly resolved into gases occupying at the high temperature of explosion comparatively enormous volumes, and consequently exert- ing tremendous pressure which disrupts the objective or drives projectiles out of guns. They may be said to consist of bodies such as nitro- glycerine and nitro-cellulose, which are explosive in them- selves, or mixtures of substances which, separately, are or may be non-explosive, but when intimately mixed are capable of being exploded either by ignition or detonators. Gunpowder is a mechanical mixture of nitre, or Chili nitre, charcoal, and sulphur in proportions of about 75, 15, and 10 respectively, and is still largely employed for blasting purposes, although it has ceased to be used as a military propellant, or nearly so. Its explosive power is due to an enormous evolution of gas from a relatively small quantity of solid substance. The nitre supplies the oxygen necessary for burning up the carbon and the sulphur, at the same time yielding nitrogen gas, It is a so-called " low explosive," while the " high explosives " have a velocity of explosion some 500 times greater. These high explosives are rich in nitrogen, and when detonated, furnish large quantities of that gas and others which are enor- mously expanded by the heat generated by the chemical changes which take place, so that they amount to from 10,000 to 15,000 times the volume of the explosive sub- stance itself. Just as nitre supplies the oxygen necessary to burn the charcoal and sulphur contained in gunpowder, so (by chemical means) hydrogen is removed from cotton (cellu- lose), glycerine, phenol, toluene, etc., and is substituted by groups of the radical NO 2 , which contain and supply the oxygen essential to the combustion of the associated carbon and hydrogen, the carbon being converted into gaseous oxides and the hydrogen into steam, while at the same time, the nitrogen is also set free in the form of gas. Some of these substances, and their nitrated forms, may be roughly indicated as follows : Cellulose (C 6 H 10 O 5 ) is chemically changed into nitro- cellulose or gun-cotton (C 12 H 14 O 10 (NO 2 ) 6 ). 2 C 6 H 10 5 + 6HN0 3 = C 12 H 14 10 (N0 2 ) 6 + 6H 2 O. 190 EXPLOSIVES EXPLOSIVES (Continued) Glycerine (C 3 H 8 O 3 ) becomes changed to nitro-glycerine (C 3 H 6 (O.N0 2 ) 3 ). Phenol (C fi H 6 O) becomes changed to tri-nitro-phenol (C 6 H 2 (N0 2 ) 3 OH). Toluol, or toluene (C 7 H 8 ), becomes changed to tri- nitro-toluol (C 7 H 5 (NO 2 ) 3 ). Nitrc-G-lycerine is a pale yellow, odourless, heavy body of oily consistency, and sp. gr. r6, obtained by the action of strong nitric acid upon glycerine. It is soluble in alcohol and ether. When decomposed by explosion the chemical changes that occur are represented by the follow- ing equation, from which it will be seen that the whole of the oxygen that is required is self-supplied, and that all the products are gaseous at the temperature of the explosion. 2(C 3 H 5 N 3 O 9 ) = 6CO 2 + 5H 2 O + 3N 2 + O. Dynamite, so largely used for blasting purposes in mines and otherwise, is a mixture of nitro-glycerine and the infusorial earth named kieselgiihr,' and has given a velocity wave of 6,000 metres per second. Blasting gelatine a stiff jelly is the strongest of all nitro-glycerine explosives, and other varieties consist of a thin jelly of nitro-glycerine thickened with from 3 to 6 per cent, collodion cotton worked up into a plastic mass with suitable proportions of potassium nitrate and wood-meal. Nitro-glycerine explosives freeze at 8 C., and have to be thawed before use. Picric Acid, or tri-nitro-phenol (C 6 H 2 (NO 2 ) 3 OH), is obtained by the graduated action of strong nitric acid upon ?henol (carbolic acid), and is itself a high explosive, t has given a velocity of 7,700 metres per second. Various mixtures of it with collodion a nitrated cellulose prepared from gun-cotton by dissolving it in mixtures of ether, alcohol, and other bodies in compressed and molten forms constitute the explosives melinite and lyddite. Gun-Cotton, or tri-nitro-cellulose, is obtained by the graduated action of nitric and sulphuric acids upon cellu- lose (cotton- waste), and smokeless gunpowders and most of the violent propellants contain gun-cotton. Dry gun-cotton is one of the most dangerous explosives, as when dry and warm it is very liable to explosion by friction. EXPLOSIVES 191 EXPLOSIVES (Continued) Tri-nitro-cellulose is a yellowish, amorphous substance soluble in alcohol, ether, benzol, acetone, amylacetate, etc. Cordite is an important military propellant, and is a mixture of gun-cotton and nitro-glycerine dissolved in acetone and thickened and rendered more stable with about 5 per cent, of vaseline. The excess of acetone is afterwards evaporated off from the gelatinous mass, which is prepared in cord form. Gelignite is a mixture of nitro-glycerine, nitro-cellulose, wood-pulp, and potassium nitrate (KNO 3 ). Tri-Nitro-Toluol (T.N.T.) is obtained by the graduated action of strong nitric acid upon toluol (toluene) (a deriva- tive of benzene obtained from coal tar), in the form of yellow prismatic crystals melting at 80-5 C., and has re- placed picric acid to a large extent as a filling for shells, being more stable in character and cheaper. Amatol An explosive made by admixing 20 parts T.N.T. with 80 parts ammonium nitrate, which gradually superseded other high explosives, including picric acid, during the recent war, as, although less rapid and shatter- ing than T.N.T., it gives greater flame, is cheaper, and practically smokeless, due to the excess of oxygen provided by the ammonium nitrate. Ammonal An explosive of the ammonium nitrate class, resembling amatol, containing finely divided aluminium in admixture. Cheddite is an explosive, the chief ingredient of which is potassium chlorate (about 79 per cent), made up of nitro- naphthalene or di-nitro-toluene (about 15 per cent.) and from 5 to 6 per cent, castor oil. Blastine is another explosive of the chlorate type. Roburite is the name of a smokeless and flameless mining explosive, in the compounding of which chloro-di-nitro- benzene is employed (as also in " Bellite "), in admixture with ammonium nitrate. Umbrite is an explosive containing 49 parts of nitro- guanidine, 38 parts ammonium nitrate, and 13 of silicon; stated to be but slightly hygroscopic and well retaining its explosive power even when moist. The amount of blasting explosives (excluding cordite, smokeless powder, sporting ammunition, etc.) manufactured in this country before the war was about 17,500 tons per annum. 192 EXPLOSIVES FATS EXPLOSIVES (Continued) Liquid oxygen explosives are made by saturating an absorptive combustible such as soot, lamp-black, or cork- meal, with liquefied oxygen, and are stated to be stronger than black powder, and can be used for some purposes instead of dynamite. EXTRACTION Taking or drawing out a solvent action by means of which the parts of a substance soluble in the solvent are extracted that is, separated from the other parts. EXTRACTS A pharmaceutical term descriptive of the con- centrated preparations obtained by evaporation of infusions or extracts prepared by the action of solvents. FARINA Potato or corn starch. FARINACEOUS Starchy. FAT HARDENING See Hydrogen, p. 252. FATS Most animal and vegetable fats, including suet, tallow, butter, and many of the various fish and nut oils, are mixtures of .distinct fats or substances chemically termed glycerides or " glyceryl esters" of stearic, palmitic, and oleic acids. The two former acids are solid and the last-named fluid in their separate forms, and the consistence of a fat or oil depends upon the relative proportion of these several fat constituents, named individually, stearin, palmitin, and olein. Lard does not contain tri-stearin. In other words, these fats or esters are combinations of fatty acids and glycerine. They all melt well below 100 C., and are all saponifiable, yielding soaps and glycerine by the process. The constitution of fat is illustrated by showing the constitutional formulae of glycerine and (for example) stearin, side by side [HO C 3 H 6 HO C 3 H 6 HO c 18 H 35 o 2 Glycerine. Stearin or tri-stearin. When stearin is saponified with caustic soda, the follow- ing change takes place : C 3 H 6 (C 18 H 36 2 ) 3 + 3NaHO = 3Na(C 18 H 35 O 2 ) + C 3 U S O^ that is to say, sodium stearate (or soda soap) and glycerine (or glycerol) are produced. Fats and fatty acids are largely used in the manufacture of soaps, candles, and margarine ; tallow and bone-fat and FATS FEELING'S SOLUTION 193 FATS (Continued) some oils are used in connection with the sizing of certain textiles to soften the effect of starch ; whilst nut and fish oils have in recent years acquired growing importance on account of the ever-increasing demand for margarine. "Stearine candles" consist for the most part of stearic acid, some proportion of paraffin or wax being added to prevent crystallization, the stearic acid being obtained by hydrolysis of the beef and mutton fats by treatment with superheated steam, or dilute sulphuric acid, or lime and water. When steam is used, the glycerine distils over with the steam, the fatty acids being left behind. The Twitchell process of saponifying fats so as to obtain glycerine and fatty acids directly, without the use of alkalies or by heating under pressure, employs a reagent obtained by allowing an excess of sulphuric acid to act on a solution of oleic acid dissolved in an aromatic hydrocarbon, such as benzene or naphthalene. The cleansed fat or oil is mixed with 50 per cent, of distilled water containing about 2 per cent, of the reagent, and the mixture is heated and kept stirred by means of an open steam coil for from ten to fifty hours, according to the nature of the fat and until it is saponified. At the con- clusion of the process, the underneath layer contains all the glycerine in watery solution, and the upper layer contains the free fatty acids. The " acid value " of fats is the number of milligrammes of potassium hydroxide required to neutralize the free fatty acids contained in i gramme. The rancidity of fats is regarded by some writers as resulting from bacterial action on the glycerides, but by others as due in the first place, to the formation of super- oxides of the unsaturated glycerides, and their subsequent decomposition (attended with the production of aldehydes and aldo-acids) by the joint action of moisture and micro- organisms. (See also Tallow, Waxes, Oils, Glycerine, Soaps, and Hydrogenation.) FATTY ACIDS See Acids and Fats. FATTY ACIDS FROM HYDROCARBONS See Petroleum. FEHLING'S SOLUTION A solution of cupric sulphate mixed with Rochelle salt (a double tartrate of potassium and sodium) and alkali, used as an oxidizing agent and em- ployed as a test for the determination of inverted sugars or other reducing agents in solution, by ascertaining the 194 FEELING'S SOLUTION FERMENTATIONS FEELING'S SOLUTION (Continued) amount of cuprous oxide produced by its action. Sugar itself does not reduce Fehling's solution, and requires to be first of all inverted. FELSPARS Compound mineral silicates of aluminium and other metals found abundantly in nature. There are many deposits in Cornwall, Ireland, Wales, and Scotland, as much as 14 per cent, potassium oxide (K 2 O) being found in some small veins of orthoclase, or potash- felspar, although most of them are not suitable for potash extraction. (See Potassium.) FELT consists of wool or hair worked into sheet form by being matted together. FENNEL OIL A colourless, aromatic oil from common fennel (A net hum faniculum\ to some extent identical with oil of aniseed. It is soluble in alcohol, ether, etc., and used in perfumery and in making liqueurs. The sp. gr. varies from 0-884 to 0*974 an d the refractive index from i'4756 to 1*5335 according to the kind and mode of preparation. FERMENTATIONS Chemical changes brought about by yeast and other forms of cell life, including bacteria, in suitable media, but directly due to enzymes, which are produced by or contained in the living cells. The act of fermentation is generally accompanied with liberation of gas (effer- vescence) and the evolution of heat. Yeast cells, for example (saccharomyces), or an extract prepared from them, but free from the living cells, contain zymase, an enzyme which breaks up sugar to the extent of about 95 per cent, into alcohol and carbon dioxide A medicinal preparation known as zymine is now made by the extraction of moist yeast cells with acetone, and, while it is quite incapable of growth or reproduction, it is much more active in inducing fermentation than they are. The most favourable temperature for fermentation is from 25 to 30 C., and living yeast cells are killed when the alcoholic strength of the product reaches about 14 per cent. The lactic fermentation or souring of milk, is induced by a bacterium known as the Bacterium lactis, but if a mixed fermentative agent is employed, such as old cheese, which FERMENT A TIONS FERTILIZERS 195 FERMENTATIONS (Continued) contains many kinds of ferment, the lactic acid first of all produced is changed into butyric acid. In the butyric fermentation of starch or sugar, induced by the Bacillus butyricus, butyric acid (C 4 H 8 O 2 ) is produced. The change of alcohol into acetic acid, as experienced in the souring of light wines or beer, is another act of fermen- tation due to enzymes. (See also Beer, Enzymes, Wine, and Yeast.) FERRATES Compounds corresponding to the manganates, of which potassium ferrate (K 2 FeO 4 ) is illustrative. FERRIC SALTS See Iron. FERRICYANIDES are compound cyanides produced from ferrocyanides by the action of oxidizing agents for example, potassium ferrocyanide (2K 4 FeCN 6 ) becomes converted into K 6 (FeCN 6 ) 2 or 2K 3 Fe(CN) 6 (potassium ferricyanide). (See Potassium Compounds.) FERRITES Compounds of ferric oxide with other oxides for example, zinc ferrite (Fe 2 O 3 ,ZnO). FERRO-ALLOYS See Iron. FERROCERIUM See Pyrophoric Alloys. FERROCYANIDES Compound cyanides of iron and other metals, of which potassium ferrocyanide is typical. They are produced from ferricyanides by the action of reducing agents, potassium ferricyanide, for example, yielding the ferrocyanide by the action of grape sugar in presence of potassium hydrate. (See Potassium Compounds and Prussian Blue.) FERROUS SALTS See Iron. FERRUGINOUS Containing iron. Many natural mineral waters are more or less ferruginous in character and act as tonics. (See Chalybeate Waters.) FERTILIZERS are materials applied to the soil to assist or promote the growth of vegetable life, and as the well-being of plants depends upon an adequate supply of the various constituents found in them and necessary to their existence and full development, they cover a very wide field and vary accordingly with regard both to the nature of the soil and the characters of the plants. They include ordinary stable manure or dung, slaughterhouse refuse, blood, bones, am- monium sulphate, nitrate, and chloride, coprolites, super- phosphate, basic slag, guano, fish meal, fish offal, potash 196 FERTILIZERS FILTER PRESSES FERTILIZERS (Continued) salts, Chili nitre, oil seed cakes, burnt lime, marl, clay, soot, seaweed, gypsum, etc. Many of these materials are described under their several names. Ammonium sulphate as produced by gasworks contains about 24^ per cent, of ammonia, and in 1914 the total production of the United Kingdom was 426,000 tons. There is little to choose between the values of this sub- stance and nitre, but it* is said that ammonium nitrate is more effective than ammonium sulphate for the growth of mangolds and wheat. The exigencies of war compelled Germany to erect plants for the fixation of nitrogen from the air, and it has been reported that the whole of the nitrogen compounds required for making explosives and for agricultural use was produced in this way. In this direction our country has now followed suit. (See Cyanamide, Nitrogen, Nitrogen Fixation, and Vegetation.) FIBRIN (Syntonin) A constituent of the blood which separates from it upon coagulation or clotting. It is of an albuminoid character, and its composition is approximately as shown : Carbon 527 Hydrogen 6-9 Nitrogen 15-4 Oxygen 23-5 Sulphur 1-2 Phosphorus 0-3 lOO'O It has been conjectured that the clotting of blood is brought about by an enzyme in the blood called thrombin, but this has not been definitely determined. FILES are used in chemical laboratories for a number of purposes, and are of three sorts. Triangular ones are used both for marking glass and assisting in the breaking of glass tubing by partially filing through the surface and then applying pressure to the weakened part. The round ones are chiefly employed for filing smooth the holes made in corks by borers, or for enlarging them ; whilst flat files are used for smoothing or reducing the diameter of corks and taking the ragged edges (by gentle rasping) off the ends of glass tubes, etc. FILTER PRESSES Mechanical contrivances of various patterns, consisting essentially of a frame carrying a FILTER PRESSES-FILTERS 197 FILTER PRESSES (Continued) number of loose slabs of filter surface which can be clamped to form a series of hollow chambers capable of withstanding internal pressure, the filter surface being ribbed or grooved and covered with cloth. Regard must of course be had to the kind of cloth and the necessary adaptation according to the chemical and physical qualities of the subject material. FILTERS or strainers provide the means of separating liquids from solids. The common laboratory form consists of a circular piece of porous paper made of a special quality which yields a minimum amount of ash when burned (in- cinerated). By folding it first of all into halves and then again into quarters, it will be found, when opened out, to fit into a funnel of appropriate size, the paper lying against the sides of the funnel. In common practice, the paper filter when so fitted and before use, is first of all moistened with a liquid of the same nature as that contained in the mixture to be filtered. Thus, for aqueous mixtures, water is applied from a wash-bottle (which see) ; for alcoholic mixtures, alcohol of the same strength should be used ; and so forth. Whatman's Extraction Thimbles are made of specially prepared filter-paper, are seamless, and can be used repeatedly for the extraction of soaps, fats, foods, rubber, etc. Paper filters can, in some cases, be used for separating two liquids of different gravities that are not miscible that is, cannot be mixed together so that they will not separate again after shaking and upon standing ; for example, a mixture of turpentine and water or olive oil and water. In such cases, if the filter be first of all wetted with water and then used, the watery (aqueous) part will pass through the filter -paper, while the oily bodies will be retained more or less permanently on the filter. There are filters or strainers of solid porous porcelain or earthenware which are sometimes employed for straining liquids from magmas or thick, moist mixtures of crystalline or other solid substances. These filters sometimes take the fqrm of solid flat plates on which the magma is placed (taking care that it does not overflow the edges of the strainer), and the liquid part gradually soaks or flows away through the texture of the filter block, leaving the more or less dry crystalline or other solid body on its surface. In 198 FILTERS -FIRE-DA MP FILTERS (Continued) other cases, strainers are constructed of funnels having their necks plugged more or less tightly with various materials known not to be chemically affected by the materials to be filtered as, for example, glass-wool, slag- wool, asbestos fibres, cotton-wool, flannel, etc. Biichner Funnel is a type of filter designed for the filtration of bulky precipitates, usually made of stout porcelain, and consists of a cylindrical cup of diameter 5 to 15 cms. wide and 3 to 5 cms. deep. The flat bottom is pierced with a number of holes and below it the funnel narrows rapidly to an outlet tube i to 2 cms. in diameter. A circular sheet of filter-paper or other filtering medium is laid down on the perforated bottom so as to cover it completely, and the cup is filled up with the liquid to be filtered. It is always used in conjunction with a suction filter pump. In manufacturing and industrial operations, appliances constructed on these principles are extensively employed, particularly where large volumes have to be dealt with, and when it is difficult to otherwise separate liquids from the mixtures to be dealt with. In laboratory practice, some such preliminary filtration has often to be made before the clouded filtrate thus prepared can be more perfectly filtered say through an ordinary paper - filter as previously described. Sand is used in waterworks for the filtration of water on a large scale, and there are many types of domestic filters, variously prepared for the purification of water. In some, animal charcoal pressed into blocks, is used and no doubt it assists the oxidation of organic matters, but does not sterilize the water. In the Chamberland-Pasteur filter a cylinder of unglazed porcelain is used, and in the Berkfeld filter a block of baked siliceous earth (kieselgiihr) is employed. Both of these remove the micro-organisms from the water, but they require periodical sterilization. In the Bischof filter, iron prepared in a spongy form is used as the purifying agent and is very useful in many circumstances. (See Filter Presses.) FIRECLAY See Clays. FIRE-DAMP An explosive gas naturally produced in coal- mines, and chiefly composed of methane (marsh gas, CH 4 ) admixed with air, nitrogen, and some carbon dioxide. FIREPROOFING-FISH OILS 199 FIREPROOFING (of Wood) A paint known as " Calcimine" has been found satisfactory for inside purposes, whilst for outside applications, a coating of zinc borate and chrome green ground in linseed oil exhibits good fire-resisting properties. FIREWORKS (Pyrotechny) are luminous devices made from combustible or explosive chemicals, largely dependent upon the use of gunpowder, metallic filings being intro- duced to produce scintillation, and many chemicals being used in association, to produce colouring and other effects. FISH GLUE See Glue. FISH OILS are of the non-drying class, and usually have an offensive odour, which, however, is removed in the chemical changes brought about by their hydrogenation. (See Hydrogenation of Oils.) When exposed to cold they are liable to deposit solid fat. Cod-Liver Oil is obtained from the liver of various species of Gadus, and especially from the torsk (Brosimus brosme). It has a sp. gr. of from 0*92 to 0-93, saponification value 171 to 189, iodine value 150 to 167, and refractive index 1*479 to 1*483. It is largely used as a nutritive food and in medicine. Dugong Oil (Manatee Oil) Obtained from the blubber of the sea cow (Halicore indicus] ; sp. gr. 0-92, saponification value 197*5, iodine value 66-6. It is used to replace cod and whale oils and for burning (in India). Herring Oil is yellowish-red, with a sp. gr. about 0*92, saponification value 180 to 194, iodine value 130 to 142, and is soluble in carbon disulphide, benzene, and ether. It is pre- pared by boiling and pressing herrings, and is used in soap making and leather-dressing. Menhaden Oil A yellowish-red oil extracted from the menhaden or moss-bunker fish, of sp. gr. 0-927 to 0*933, saponification value about 190, and iodine value 140 to 180. It is soluble in ether, naphtha, carbon disulphide, and benzol, and is used in leather-dressing, etc. Porpoise Oil is extracted by boiling the various parts of the brown porpoise, and is of pale yellow colour, of sp. gr. about 0-926, and iodine value according to the part of the body yielding same. It is used in making lubricants, soaps, leather-dressing, etc., and is soluble in ether, chloro- form, carbon disulphide, and benzol. The quality prepared from the jaw of the porpoise is used in particular as a lubricant for watches, 200 FISH-OILSFLAME COLOURATION FISH OILS (Continued) Sardine Oil is prepared like herring oil and is of a yellow colour, of sp. gr. about 0-93, saponification value about 190, iodine value 180 to 193, and refractive index i'48. It is soluble in alcohol, benzine, etc., and is used in soap-making and as a lubricant. Seal Oil derived from Squalus maximus, is white or straw- coloured, of sp. gr. 0-924 to 0-926, with saponification value of 189 to 196, iodine value 127 to 159, and refractive index 1-474. It is soluble in benzene, chloroform, ether, and carbon disulphide, and is used in soap-making. Shark Oil is of much the same character as seal oil, but is yellow to reddish-brown in colour, and is used not only in soap-making, but also in paint manufacture and for currying leather. Sperm or Whale Oil comes from the blubber of Balana mysticetus and other species ; is yellowish-brown, of sp. gr. about 0-925, having a saponification value of 188 to 193 and iodine value 120. It is soluble in alcohol and ether, has a strong fishy odour, and is used in soap-making, for lubricat- ing, and as a leather dressing. Tuna Oil (tunny-fish oil) is pale yellow to red-brown in colour, and is expressed from the livers of Thynnus vulgaris. It has an iodine value of about 156, is soluble in alcohol, ether, etc., and is used in' paint-making, etc. Other varieties of fish oils are those called Black-fish, Halibut, and Salmon Oils. A characteristic fatty acid of the fish- oil group is the substance named clupanodonic acid, which occurs in the mixed fatty acids obtained from Japanese sardine oil, herring and whale oils, etc. It is a pale yellow liquid of fishy odour, which readily oxidizes on exposure to the air to a varnish-like mass. (See Oils.) FIXED OILS See Oils. FLAME Gas in a state of illumination (incandescence) pro- duced by great heat. (See Light and Burners.) FLAME COLOURATION Many chemical compounds com- municate distinct colouration to an otherwise colourless or nearly colourless flame, such as that of the blow-pipe or Bunsen burner. (See Spectroscope.) FLA ME COLO URA TIONFLA VONE 201 brick-red green red white FLAME COLOURATION (Continued) Potassium salts give a lilac colour to the flame. Sodium yellow Calcium Barium Strontium Magnesium Copper Lithium brilliant crimson colour to the flame. Lead, arsenic, and antimony compounds give a bluish-white colour to the flame. FLASH-POINT is the temperature at which an oil or other combustible fluid gives off vapour which will then fire if exposed to a naked light. The appliance used in this country for determining flash-points is one known as Abel's, but on the Continent another one named Pensky's is used. FLASKS are glass vessels of varying shapes for holding liquids, consisting of a body part with flattened bottom, and a neck which can be easily grasped by the hand or held by a clamp, and closed with a cork when required. The glass of which they are made is of a quality to permit the contents to be heated (as when placed on a sheet of wire gauze over a lamp or on a heated sand-bath) to the tem- perature of boiling water. (See Aspirator and Gas Gene- rators.) Erlenmeyer Flask A glass flask of the "conical" type, having a flat bottom of diameter equal to from half to three-quarters of its height, and with side surface tapering smoothly from that base to the bottom of the neck, which is short, narrow, and straight-sided. These flasks have the advantage of being more easily washed out than round flasks, but they are somewhat more liable to crack on heating. FLAVIN A yellow dyestuff imported from the United States of America (possibly identical with quercitrin), imperfectly soluble in water. (See Quercitrin.) FLAVONE (C 15 H 10 O 2 ) The parent substance of a number of yellow dyes found in the vegetable kingdom, many of which occur in the form of glucosides. The flavone family is usually divided into "flavone" and " flavonal " compounds, and there appears to be a genetic relationship between the flavone and anthocyanin series of bodies, inasmuch as cyanidin can be produced from quercitrin by a reduction process. (See Plant Colour- ing Matters.) 202 FLAX FLUORINE FLAX (Linum usitatissimum) is a plant extensively grown in Ireland, Belgium, France, Russia, and other countries for sake of the fibre (which is the raw material of linen), the linseed oil which is extracted from it, and the residual cake which is used for cattle food. It contains from 32-77 to 38-42 per cent, of fat, and from 3-33 to 5-29 per cent, nitrogen. (See Linseed Oil.) FLINT A variety of quartz. (See Silica.) FLOTATION OILS AND PROCESS See Ores (treatment). FLUELLITE A native fluoride of aluminium. FLUOR (Fluorspar) See Fluorine. FLUORAPATITE A mineral of composition 3P 2 O 8 Ca 3 ,CaF 2 . FLUORESCEIN (Resorcinol-phthalein) (C 20 H 12 O 5 + H 2 O) is a dark red, crystalline powder, soluble in alcohol to a yellow-red colour, and in alkalies to a red colour, showing a fine green fluorescence. It is easily reduced to fluoreecin, of which the potassium salt is the magnificent dye eosin. All these substances are extensively used in the dyeing industries. (See Eosin.) FLUORESCENCE The property of producing opalescent colour or bloom different from that of the liquid or substance which exhibits it. Green crystals of fluorspar give blue re- flection, and quinine sulphate solution is strongly fluorescent. FLUORINE (Fl) Atomic weight, 19. Fluorine is found in nature combined with calcium in the mineral fluorspar (CaF 2 ) (also known as Derbyshire spar) and is a constituent of cryolite (Na 3 AlF 6 ) a double fluoride of sodium and aluminium found in Colorado and Greenland and other minerals. It is also present in small quantities in bones and the enamel of teeth. Fluorine can be obtained in quantity by the electrolysis of fused potassium hydrogen fluoride or of anhydrous hydrofluoric acid at 23 C., and is, at ordinary tempera- tures, a pale yellowish gas of very active chemical, corrosive, and poisonous qualities, which attacks glass with avidity, but is insoluble in water. When cooled to a temperature of 187 C. it condenses to the liquid state in the form of a mobile yellow fluid with a characteristic odour something like that of chlorine, and at a still lower temperature it assumes the solid form and is almost white. Fluorine acts strongly upon all metals, even gold and platinum to some extent, and many of them pass into a state of inflammation when thrown in a finely divided state into the gas. It also attacks organic substances with violence,. FLUORINE FLUX 203 FLUORINE (Continued) A combination with hydrogen known as hydrofluoric acid gas (HF) is made by warming a mixture of strong sul- phuric acid and powdered calcium fluoride in a leaden or platinum vessel : CaF 2 + H 2 S0 4 = CaS0 4 + 2 HF. It is very soluble in water, and is largely employed for etching purposes, as, for example, making the graduations on glass measuring apparatus. The object to be marked in this way is coated with melted wax, and after making the design or marks on the coated glass, it is exposed to the action of the acid either in the form of gas or liquid, with the result that the glass is eaten into where exposed by the markings, the fluorine having no action on the wax. For some commercial purposes, an aqueous solution of this acid of 60 per cent, strength is produced. Hydrofluoric acid vapour is irritating and injurious to the respiratory organs, and the liquid produces ulcerated sores on the skin, and is altogether a very dangerous chemical compound. There are fluorides corresponding to the chlorides and also a number of double fluorides. The fluorides of potassium, sodium, and iron are but sparingly soluble in water, while the fluorides of silver and tin are easily soluble. Most of the fluorine compounds are easily fusible, and when ignited in a current of steam many of them are converted into oxides and hydrofluoric acid is evolved. FLUORSPAR or FLUORITE occurs in blue and green forms, and sometimes consists of 99-5 per cent, calcium fluoride (CaF 2 ). The fluorspar production in this country amounted in 1918 to 53,498 tons, of which 30,000 tons were used for fluxing purposes and in the glass industry. FLUX A substance or mixture used to assist fusion by heat. One such flux is a mixture of nitre and tartar, and it is either placed in the crucible in which the mineral is to be fused, or gradually introduced. The oxygen of the nitre causes the combustion of the carbon of the tartar and assists to raise the temperature of the mass. Potassium cyanide and other chemicals are used as fluxes according to the nature of the mineral or other substances to be fused. Black flux is a mixture of potassium or sodium carbonate, sodium nitrate, and carbon, used in assaying ; and white flux is a mixture of sodium carbonate with sodium nitrate and sodium nitrite used in metallurgy and welding. 204 FOCUS-FOODS FOCUS The point at which the rays of light come together after passing through a convex lens. FOIL, or a very thin sheet of metal, finds frequent use at the hands of the chemist. Platinum foil is particularly useful, inasmuch as it is not acted upon by most chemicals and withstands exposure to high temperatures. It is conse- quently employed to test the behaviour of solid substances when exposed in crystal or powder form to heat varying from mere warming up to redness. For this purpose it is held by tongs or forceps. If, for instance, a small quantity of crystallized borax (Na 2 B 4 O 7 ioH 2 O) be placed on a piece of platinum foil and heated over a Bunsen flame, it will be seen to swell up, lose its water of crystallization, and finally fuse to a clear glass-like appearance. Lead, copper, tin, zinc, aluminium, and magnesium are also prepared in the form of foil, and are required from time to time in the laboratory. FOODS are the other substances which, in addition to water and air (both of which are also essential to life), serve to repair the various tissues of the body and to renew its energy. They are generally classified under the headings of proteins (albuminoid matters), carbohydrates (starch, sugar, etc.), and fats, although vegetable acids and mineral salts are essential to a perfect dietary, as also a small quantity of the mysterious substances called hormones (which are secreted in the body by certain glands) and vitamines. (See Vitamines.) Tea, coffee, and alcohol are often regarded as mere stimulants or accessories, but while tea and coffee may be so viewed, alcohol is a real food when taken in moderation, all of it being consumed in the body and serving to replace so much other food. It is usual nowadays to calculate food values in terms of calories (heat units), a kilo-calorie being the quantity of heat sufficient to raise a kilogramme (1,000 c.c.) of water one degree Centigrade, and it is reckoned that proteins and carbohydrates each produce 4*1 calories for every gramme consumed as against 9-3 calories for each gramme of fat consumed. A committee of the Royal Society reported during the recent war that each man engaged in active work requires per day 100 grms. or 3^ ozs. protein (albuminoids), 100 grms. or 3! ozs. fat, and 500 grms. or 17^ ozs. carbohydrates, totalling approximately 3,400 calories per man per day. In this connection it should be remembered that fats and FOODS FORCE 205 FOODS (Continued) carbohydrates are to some extent interchangeable and both are similarly interchangeable with alcohol to some degree. Taking the five pre-war years the following table gives the quantities in metric tons (2,205 Iks.) of tne tota l foods imported and home produced : Energy Amounts. Protein. Fat. Carbo- hydrate. Value. Millions of Calories. Metric Metric Metric Metric Tons. Tons. Tons. Tons. Cereals 4,865,000 549,000 63,000 3,628,000 17,712,000 Meat 2,685,000 356,000 799,000 8,890,000 Poultry and eggs, 331,000 42,000 3I,OOO 461,000 game and rabbits Fish Dairy produce (in- 848,400 5,231,800 91,000 199,000 17,000 686,000 258,000 531,000 8,253,000 cluding lard and margarine) Fruit 1,271,000 9,000 14,000 222,OOO 1,077,000 Vegetables 5,482,000 120,000 10,000 1,031,000 4,8l2,OOO Sugar (including 1,657,000 5,000 18,000 1,572,000 6,633,000 cocoa and choco- late) Cottage and farm 67,000 13,000 551,000 2,655,000 produce not in- cluded above Total 1,438,000 1,651,000 7,262,000 51,024,000 Grms. Grms. Grms. Calories. Per head per day ... 87 IOO 44 3,091 Per " man " per day H3 130 571 4,009 (See Gastric Juice, Chyle, Chyme, Bile, and Pancreatic Juice.) FORCE Matter and force are inseparable. Indeed, it may be said that the different kinds of matter owe their phases to the forces that rule their existence. They are not separable : there is no force without matter, and no matter without force. A metal wire is affected by and conducts the electric current ; a strip of metal conducts the heat to which it may be exposed, from one end to the other. It is through the medium of the matter filling the spaces between, that the light from the sun and the moon is conveyed to the earth. The space between a magnet and iron filings placed upon 206 FORCE FORCE (Continued) a sheet of paper acts as the medium of the magnetic force from the magnet to the iron filings, as evidenced by the iron filings following the magnet when moved from one to another part of the paper. When a wire of magnesium metal is strongly heated in the air, it burns with an intense white light, and through the space between, the light from the burning metal is conveyed to the eyes. Force, like matter, is indestructible and unchangeable except as to its form or variety. Just as matter can be made to change its form or character and properties, so force can be made to change its form and character. Heat can be changed into light ; light can be transformed into heat ; electricity can be changed into heat ; and all may be converted into mechanical action or power. Matter may be defined as consisting of an indefinite number of recognizable entities, and the distinct characters or properties by which we recognize the many varieties are the expressions meaning thereby, their appearances, pro- perties, and their relations to other substances given to them by the forces which control them. Sugar is a so-called carbohydrate, consisting of carbon in combination with the elements of water, and if strong sulphuric acid (oil of vitriol) be allowed to fall upon a lump of sugar and warmth applied, a great chemical change rapidly occurs. The strong acid seizes upon the water elements (forming part of the sugar) with tremendous avidity, and the carbonaceous part of the sugar is set free in the form of a black mass. Some of the water thus seized by the acid is evaporated owing to the great heat that is given off in the chemical interaction. Now, where does the heat come from ? Both the sugar and the acid are only warm to start with, yet directly they meet great heat is given off. It must come from the forces which are locked up in the sugar and the acid. What becomes of this heat ? Some of it causes the evaporation of the water (given off as steam) which the acid takes out of the sugar ; another part is radiated through the air, for the heat can be felt. In any case, heat is lost to what was originally a mixture of sugar and acid. In other words, there is a dis- sipation of energy in the form of heat from forces that were in some way locked up in the two varieties of matter which when placed in contact, underwent chemical change attended with the results here described. FORCE 207 FORCE (Continued) So, again, in the burning of a wire of magnesium metal in the air, not only is great heat given off, but also much bright light, showing that magnesium and oxygen do not consist of mere matter as something distinct from force, but that they are, like all other substances, compounded of the two things. (See Matter.) Mechanical force is capable of bringing about certain chemical changes. For example, a mixture of potassium chlorate and sulphur enters into chemical action with explosive violence, when placed upon a hard surface, as of iron or stone, and hit with a hammer, or when rubbed together with a pestle in a mortar. It may be, however, that in such cases, the energy or the friction causes the local emission of heat, as in the striking of matches, and that the heat thus developed is the immediate cause of the chemical changes that are induced. Again, a mixture of hydrochloric acid and phosphine (phosphoretted hydrogen) gases, when exposed to pressure, undergoes chemical combination, and there is produced a solid crystalline substance known as phosphonium chloride (PH 4 C1). The same compound is produced also by pass- ing the mixed gases through a tube immersed in a freezing mixture, and it is again dissociated into the originating substances when exposed to the air under normal pressure. Force takes a part in every chemical change, but this part is, unfortunately, not revealed by the symbolic equa- tions used by chemists to represent the more material sides of these changes. For example, the equation SO 3 + H 2 = H 2 SO 4 expresses the formation of sulphuric acid by a combination of sulphuric anhydride and water, but it does not reveal the fact that the combination involves an expenditure of energy disengaged as heat, sufficient to raise the temperature of 213 grammes or cubic centimetres of water from o to its boiling-point 100 C. A mass of 772 pounds falling through i foot of space produces by friction sufficient heat to raise the temperature of i pound of water i F. When water is changed into ice, a certain amount of heat is evolved, and, on the other hand, when water is changed into steam a larger amount of heat is absorbed. Again, when nitrogen trichloride is suddenly heated, it explodes with great violence and is resolved into its elements, 208 FORCE FORMALIN FORCE (Continued) and in this change a tremendous amount of energy is used up in overcoming the atmospheric pressure which acts as a restraining influence. So it is with every chemical change. The energy that is expended may reappear as light or electrical force, or in what is commonly regarded as its lowest degraded form viz., heat ; but there is no absolute destruction or annihila- tion of force. All matter being, as it were, made up of substance and force, there is a redistribution but no loss of either when undergoing chemical change. That the recent investigations concerning the atomic structure of chemical entities will lead to the conclusion that all the forms of matter are to be ascribed to move- ments of the ultimate particles of two primordial elements in the nature of positive and negative electricity is not at all clear and cannot be accepted until the nature of the nuclei of the atoms has been definitely ascertained. It is far more likely that while there may be oneness of ultimate matter, all its changes are to be attributed to the forces, whatever they may be, that control it, determine all its phases, and are indissolubly bound up with it. (See Elements and Radio-activity.) FORMALDEHYDE or METHYL ALDEHYDE (CH 2 O) is a gas soluble in water, and a solution of 40 per cent, strength is an article of commerce, largely used for disinfecting and preservative purposes. It has a very irritating action on the mucous membranes of the eyes, nose, and throat. It is made by a contact action brought about by passing a current of methyl alcohol vapour admixed with air over a glowing platinum or copper spiral, and absorption in water, in which solution it has the hydrate formula CH 2 (OH) 2 . It possesses the property of making gelatine in any form insoluble in water, and this is utilized in many technical applications, including the preservation of adhesives and anatomical specimens. It is also used in the processes of making bakelite and other allied articles. The polymeric solid white paraform is more useful for disinfecting rooms by fumigation, as it is easily vaporized and is equally effective per unit of active agent. Formaldehyde is believed to play an important part in the process of plant assimilation. FORMALIN A commercial solution of 40 per cent, formalde- hyde in water, used as a disinfectant. FORMA MIDE FORMULA 209 FOEMAMIDE See Amides. FOEMIC ACID (CH 2 O 2 ) occurs naturally in ants, in stinging- nettles, in the processionary caterpillar, the fruit of the soap- tree (Sapindus saponaria), in fir cones and tamarinds, and is also formed as a by-product in the atmospheric oxidation of turpentine. When pure, it is a colourless liquid of sp. gr. i'2i78, which solidifies at- i C., and fumes in the air. It is a powerful antiseptic, very corrosive, and mixes with water in all proportions. For commercial purposes it is prepared of 70 and 80 per cent, strengths, and finds industrial applications in the textile and tanning trades. " FORMITE " A proprietary phenol-formaldehyde product, used as an electrical insulating material and plastic cement. It is unaffected by oils and many solvents, and solutions of it are made up as varnishes for special applications. FOEMOSE (C 6 H 12 O 6 ) A mixture of glucoses obtained by the action of lime-water on formaldehyde, with which it is polymeric. FOEMUK5! The arrangement of symbols representing the chemical composition of substances. The symbols which are used are explained in the several sections dealing with Chemical Compounds, Chemical Interactions, and Elements, and the formulae employed are of various types. The ordinary formulae indicate the molecular composition with- out respect to any particular molecular arrangement or structure ; thus NaCl expresses the combination of i atom of sodium with i atom of chlorine in i molecule of salt. Again, the formula (NH 4 ) 2 SO 4 expresses the combination of 2 of the groups NH 4 with i of SO 4 in i molecule of ammonium sulphate, and so forth. The empirical formula of a substance is ascertained from the results of its analysis, the percentages of elements found present being divided by their atomic weights. For example, hydrocyanic acid upon analysis is shown to contain as follows: Hydrogen ... ... 3704 per cent. Carbon ... ... 44'444 Nitrogen ... ... 51-852 and if these percentages are divided by the atomic weights of the three elements viz., H = i, C = i2, and N=i4 it will be found that the quotients are practically identical, so that the component elements are combined in the pro- portions of one each viz., HCN, which is the simplest formula of the substance, 2 1 o FORM ULMFRA NKINCENSE FORMULAS (Continued) Or again, taking salt (sodium chloride), it yields upon analysis 39*31 6 per cent, sodium and 60*684 per cent, chlorine, and the division of these numbers by the atomic weights 23 and 35-5 shows the two components to be con- tained in the elemental proportions so that the empirical formula is NaCl. Constitutional or Rational formulae, on the other hand, are used to express a sense of construction or structure, as when, for example, ammonium cyanate is resolved by heating into urea, the change may be expressed as follows : CNO(NH 4 ) = CO(NH 2 ) 2 in order to show that, although empirically the composition of the two substances is the same, being concretely ex- pressed by the formula CN 2 H 4 O, the molecular arrange- ments or structures are different. Again, the empirical formula of ethyl alcohol is C 2 H 6 O, but when expressed constitutionally as C 2 H 5 (HO), it is seen that the molecule has an alcoholic structure and that the group HO can be replaced or substituted by other groups. So again, acetic acid (C 2 H 4 O 2 ) may be expressed constitu- tionally in several ways, thus : CH 3 C^ X)H that is, carbon in association with the groupings CH 3 , OH, and the oxygen atom ; otherwise as CH 3 ,CO,OH that is, the radical methyl, the radical hydroxyl, and oxygen all in direct combination with the carbon; or as H(C 2 H 3 O 2 ) that is, as hydrogen acetate or a molecule of hydrogen in which i atom is replaced by the group C 2 H 3 O 2 , according to the views taken of the structure of the acetic acid molecule. FRACTIONAL DISTILLATION affords the means of separ- ating, more or less, the several constituents of mixed distil- lable liquids, by collecting the portions or fractions which pass over at varying temperatures. For example, alcohol boils at 78 C. and aniline at 185 C., so that a mixture of the two substances can be separated by this process. (See also Boiling-point and Retort.) FRANKINCENSE (Gum thus) An oleo-resinous exudation from the spruce fir (Abies excelsa), from which burgundy pitch is made by melting and straining it through a cloth. FRANKLINITE FULLER'S EARTH 211 FRANKLINITE An iron-manganese-zinc ore found in New Jersey and elsewhere, having the composition (ZnFeMn)O, (FeMn) 2 3 . FREEZING MIXTURES are employed by chemists to lower the temperature at which chemical interactions may occur, and there are many kinds available. One of the simplest is a mixture of ammonium nitrate (NH 4 NO 3 ) and water in equal parts, the dissolving of the salt causing a drop in tempera- ture from 40 F. to 4 F. By the use of a mixture of 2 parts snow or pounded ice and i part salt, a steady temperature of - 4 F. can be maintained ; while one of 2 parts snow and 3 parts crystallized calcium chloride (CaCl 2 ) will bring the temperature down from 32 F. to 50 F. (See Heat.) FRENCH CHALK (Steatite or Soap-stone) A soft silicate of magnesium mineral, talc-like in nature. FRENCH POLISH A solution of shellac in alcohol, other resins being sometimes incorporated. FRIT The materials used in compounding glass and enamels as obtained by the baking or calcination of them, but before fusion. FRUCTOSE (Laevulose) A fermentable form of crystallizable fruit sugar (CgH^Og) found accompanying glucose in the juice of sweet fruits and in honey. It melts at 95 C., and can be prepared from cane sugar by hydrolysis with hydrochloric acid. It has also been made from various plant sources, including artichokes. It is soluble in water, alcohol, and ether, and is laevo-rotatory in character. FRUIT SUGAR See Fructose. FUCHSINE (Roseine) Another name for magenta, one of the aniline dyes used in the textile and leather industries. (See Magenta.) FUEL (liquid) See Colloidal Fuel. FULLER'S EARTH A natural porous and absorptive alu- minium silicate, of greyish, yellowish, or greenish colour, widely distributed and largely produced both in England and in the United States a powerful absorbent of oily matters. At one time it was extensively used for " fulling " clothes, but now it is chiefly employed in connection with the bleaching and filtering of fats and oils, as a carrier of pigments, the removal of grease from woollen goods, and as a toilet article. The English supply of Fuller's earth comes chiefly 212 FULLER'S EARTH FUMIGATION FULLER'S EARTH (Continued) from Surrey quarries and some Somerset mines ; an analysis of the Nutfield earth showing 58-66 per cent, silica, 17*33 P er cen t- alumina, 7*21 per cent, ferric oxide, 3-17 per cent, lime, 3-26 per cent, magnesia, 1-63 per cent, soda and potash, and loss on ignition 874 per cent. FULMINATING- GOLD A compound of auric oxide (Au 2 O 3 ) and ammonia, of explosive character, the exact chemical constitution of which has not been ascertained. FULMINATING MERCURY or FULMINATE OF MERCURY (HgC 2 N 2 O 2 ) A dark brown, crystalline compound used for priming percussion caps and in making detonators. It explodes when dry under the slightest friction and has to be kept wet until used. It is prepared by the action of strong nitric acid upon mercury and alcohol. FULMINATING SILVER is prepared by dissolving silver oxide (Ag 2 O) in strong ammonia, and is an explosive com- pound, possibly of the nature of a nitride (Ag 3 N). FULMINIC ACID (HCNO) Known chiefly in its combinations and said to be produced by the action of sulphuric acid on a solution of potassium fulminate followed by extraction with ether. It is the oxime of carbon monoxide. See Oximes. FUMARIC ACID (C^^OJ is a natural constituent of some plants and lichens, including Fumaria officinalis, Glaucium flavum, and Iceland moss. It crystallizes in colourless prisms, is inodorous, has an acid taste, and is readily soluble in hot water, alcohol, and ether. It is nearly allied in constitu- tion to malic acid, and it is resolved into succinic acid by the action of reducing agents. FUMIGATION Exposure to the action of vapours or fumes, as when fumigating a room by sulphur dioxide generated from a burning sulphur candle, for the purpose of disin- fection. A recent investigation has established the fact that the vapours of formaldehyde and paraform have identically the same value as germicidal agents when used for fumiga- tion of rooms, and that the presence of water-vapour does not facilitate the disinfection. By the same investigation it was also proved that a sulphur candle of 9 ozs. weight burned in association with the avaporation of 6 ozs. of water, suffices to sterilize a room of 1,000 cubic feet capacity FUMIGA TION-FUSION 213 FUMIGATION (Continued) within two hours, while 20 grms. of paraform or if ozs. of 40 per cent, solution of formaldehyde are equally effective. FUMING SULPHURIC ACID See Nordhausen Acid and Sulphur. FURANE (Furfurane) See Furol. FURNACES, as used in laboratories, are of various descriptions. The electrical furnace is only to be found in highly equipped establishments, and some references to its industrial applica- tions will be found elsewhere. (See Electricity, Heat, Reverberating Furnace, and Organic Analyses.) FUROL or FURFUROL (CgH^) is a colourless, inflammable, volatile, aromatic oil, obtained by distilling sugar, wood, or bran with moderately strong sulphuric acid. It turns brown upon exposure to the air, has a sp. gr. of 1*1594, and boils at 162 C. It finds some employment in the arts, and, as prepared from corn-cobs, is likely to be of service in the production of synthetic resins. It has chemical re- lationship to furfurane, a colourless, mobile liquid contained in pinewood tar, with an odour something like that of chloroform, and which boils at 32 C. FUSEL OIL A mixed residue of alcohols of higher boiling- point than ordinary ethyl alcohol, together with some aldehydes, esters, and other substances, including pelar- gonic and capric acids, left as a by-product from the dis- tillation of alcohol produced by fermentation, particularly that from potato starch. One of its chief constituents is isoamyl alcohol. It has an unpleasant odour and taste, and it is therefore of importance to remove it from spirits intended for consumption. (See Amyl Alcohol.) FUSIBLE METAL An alloy, the melting-point of which largely depends upon the proportion of bismuth employed, generally about 50 per cent, with lead about 25 per cent., tin 12 to 13 per cent., and cadmium about 12 to 13 per cent. It has a fusing-point of 67* 5 C., and is used for producing casts of metals, solders, and in making safety valves for boilers, fusible plugs, valves, etc. (See Bismuth.) FUSION The liquation, or melting into the fluid state, of solids by means of heat. The temperatures at which this liquation takes place are called the fusing or melting points. (See Liquation and Metals.) 214 FUSTIC EXTRACT GALLIUM FUSTIC EXTRACT (Cuba wood) is the name of a yellow dye of two varieties viz., "old fustic," obtained from Morns tinctoria (yellow Brazil wood), and "young fustic," from Rhus cotinus. The colouring matter itself is named fustin, and is used in the textile and leather industries. GADOLINITE A complicate silicate mineral found in Norway and Sweden (known also as yttrite and ytterbyite) of black, : brown, and yellow colour, containing the rare earths yttria, ceria, etc. ; also found in pegmatites in Arizona, Colorado, and Texas. GADOLINIUM (Gd) Atomic weight, 157-3. A very rare and but little known element of the terbium group, found present in samarskite, orthite, cerite, etc. GAHNITE (Zinc spinnelle) A natural zinc aluminate (ZnO,Al 2 3 ). GALACTOSE (C 6 H 12 O 6 ) A colourless, crystalline carbo- hydrate, soluble in water (prepared by oxidation of dulcitol), which melts at about 170 C. GALBANUM A resin imported from the Cape and Persia, and reported to be produced from the umbelliferous plant Babon galbanum or Ferula galbaniflua. GALENA See Lead. " GALILITH " A product made from casein, hardened with formaldehyde, and used in making buttons and cheap combs, etc. GALIPOT A French name for resin from the Pinus mavitima. GALLIC ACID (C 7 H 6 O 6 ) occurs in nut galls, sumach, tea, and a number of tannins in the form of a glucoside, from which it can be made by boiling with acids. In the pure state it crystallizes in nearly colourless silky needles of the com- position C 7 H 6 O 5 ,H 2 O, which are soluble in water, ether, and alcohol. With fer r ous sulphate it gives a brown colour, which quickly blackens on>. xposure to the air, and is used in photography and the manufacture of ink. (See Inks.) GALLIPOLI A crude olive oil used in the textile industries. GALLIUM (Ga) Atomic weight, 69-9; sp. gr., 5-88; melting- point, 2975 C. A rare metal occurring in very minute amounts in certain specimens of zinc blende from the Pyrenees. Little is known about it beyond its spectro- scopic character. It is a grey lustrous metal which com- GA LLI UMGA NISTER 2 1 5 GALLIUM (Continued} bines rapidly with chlorine, is soluble in warm hydrochloric and nitric acids, and forms an alloy with aluminium. It decomposes water at high temperatures, and its compounds resemble those of aluminium. GALL NUTS are produced as excrescences on the leaves (and their stalks) of the oak (Quercus infectoria) by punctures of gall-wasps, in which they lay their eggs. The Aleppo galls are most valued, but although those from the Levant (con- taining about 58 per cent, tannin) are the best, there are others of inferior quality which come from Dalmatia and other places. They contain tannic or gallo-tannic acid, which is also present in sumach and tea, and are used in tanning, in the manufacture of blue-black ink, also for the pro- duction of certain tints in Turkey-red dyeing and in calico- printing. (See Inks.) GALLO-TANNIC ACID A colourless, amorphous substance found in nut galls (gall nuts),etc., which has been credited with the formula C 21 H 22 O 17 (Strecken), and regarded as a compound of grape sugar and gallic acid in the molecular proportion 1:3; but it has more recently been proved to be a sugar ester of complex formula, and it is claimed to have been synthesised. (See Tannic Acid.) GALVANISM See Electricity. GALVANIZING Iron coated with zinc by immersion in molten zinc, after suitable preparation by cleansing, etc. Cold galvanizing is stated to be carried on commercially by the electrolysis of zinc sulphate solution, using a zinc anode. It has been computed that one-half of the total zinc production is used in galvanizing. GAMBLER The inspissated juice of an Indian plant (Uncaria gambier), which grows also in Malacca, and is largely used in dyeing and tanning. It is principally imported from Singapore. GAMBOGE A gum resin from the Stalagmites cambogioides tree which grows in Cambogia (Siam). It acts as a drastic purgative, but as prepared in cakes for the market it is chiefly used as a pigment for water-colour painting. GANGUE The mineral matter enclosing or intimately asso- ciated with metallic and other ores. GANISTER A highly refractory siliceous sedimentary rock, used for lining blast and other furnaces. 2i6 GARNET GAS GARNET Name of a variety of crystalline minerals (almandite, andvatite, essonite, etc) of varying colours, consisting of double silicates of various bases, including alumina. GARNIERITE A hydrated silicate of nickel and magnesium. (See Nickel.) CKAS (Coal) The composition of coal gas as produced for illuminating purposes depends very largely upon the tem- perature at which the roasting of the coal takes place, and upon the amount of air that gains access to the retorts. It contains not only permanent gases but, in addition, con- siderable quantities of the vapours of volatile hydrocarbons, to which its luminosity in burning is due. The greater proportion consists of hydrogen (about 35 to 50 per cent.), which burns with a practically colourless flame, and marsh gas or methane (CH 4 ) (about 35 to 40 per cent.), which also gives but little light when burned alone. Accompanying these constituents there are proportions of carbon dioxide, carbon monoxide, nitrogen, and oxygen. The illuminating power of coal gas is chiefly attributable to olefiant gas and other associated hydrocarbons, which, in all, amount to about 5 per cent., and the process of roasting the coal is conducted in such a way as to yield about 10,000 cubic feet of gas per ton of coal. In 1913, about twenty million tons of coal were carbonized in the United Kingdom for the manufacture of coal gas. The composition of good coal gas according to one analysis, which is fairly representative, is as follows : Hydrogen ... ... ... 48-2 per cent. Methane ... ... ... 34*2 Carbon monoxide ... ... 6*6 Olefines and benzene ... ... 5-3 Nitrogen, carbon dioxide, and oxygen 57 loo-o The gas, however, now supplied in many places consists of a mixture of ordinary coal gas with so-called water gas, or carburetted water gas that is, the mixture of carbon monoxide and hydrogen which is produced by passing steam over red-hot coke, while at the same time a certain quantity of petroleum is introduced and destructively de- composed or " cracked " in the furnace, to give to the other gases that proportion of hydrocarbons necessary to give lumin- osity to the whole mixture when it is burned. (See Coal.) GASES 217 GASES In addition to the recently discovered rare elements contained in the air, five of the better known ones exist ordinarily in the gaseous state viz., hydrogen, oxygen, nitrogen, chlorine, and fluorine. Gases vary greatly in their general properties, being of varying colours (although mostly colourless), densities, solubilities in different fluids, and chemical affinities. They can all be reduced to the liquid or solid state by lowering the temperature and increasing the pressure sufficiently, and the highest temperature at which a gas can be liquefied by pressure is called its "critical temperature," while the "critical pressure" is that under which it can be liquefied at its critical tempera- ture. Many gases are readily absorbed by charcoal, and some of them are occluded by metals. (See Palladium and Occlusion.) Recently heated beechwood charcoal will absorb by what is called " surface action " (see Adsorption) 90 times its own volume of ammonia, while that from cocoa-nut shell will take up 171 volumes. The gases most easily liquefied are those which are most readily absorbed by charcoal, and in this condensed (or maybe partially liquefied) form they exhibit unusually active chemical pro- perties. For example, powdered charcoal saturated with hydrogen sulphide when brought into contact with oxygen, bursts into combustion owing to the rapid chemical action of the two gases. All gases tend to expand and the pressure or elastic force of a gas is the collective effect of the bombardment of its freely moving molecules against the containing vessel. A list of the critical temperatures and pressures and boiling-points of the better known gases is appended : Gas. Critical Temperature. Critical Pressure : Atmospheres. Boiling-point under 760 mm. Pressure. Ammonia 132-9 C. 1 12-3 - 33-46 c. Carbon dioxide 3l'0 72-9 - 80'0 Chlorine 141-0 83-9 - 337 Hydrogen -241-0 19-4 -252-5 Nitrogen ~ 145-0 33-6 - 195-5 Oxygen -118-8 50-8 -182-9 Sulphur dioxide 157-2 777 - 10-1 218 GASES GAS GENERATORS GASES (Continued) Equal volumes of gases at the same temperature and pressure contain an equal number of molecules, and the volume occupied by a given weight of any gas is inversely as the pressure. The densities of the gaseous elements are, for the most part, identical with their atomic weights (phosphorus and arsenic are two of the most noticeable exceptions, their vapours possessing a density twice as great as that re- quired by the general law). The densities of compound gases are one-half of their molecular weights. (See Vapour Densities.) One litre of hydrogen at o C. and 760 mm. mercury weighs 0-08936 grm., and the weights of litres of other gaseous elements are ascertained by multiplying this factor by their atomic weights. Gases expand ^|^ part of their volume at o C. for every increase of i C. in temperature at constant pressure. Gases exhibit a peculiar property of diffusion, so that if two vessels containing, say, oxygen and hydrogen respec- tively, be placed with their openings in contact, each gas will mingle with the other so thoroughly and automatically, that after a time, there is uniformity of composition of the gases contained in the several vessels. It has been ascer- tained that the relative velocities of diffusion of any two gases are inversely as the square roots of their densities. This diffusion is readily appreciated if it be borne in mind that gaseous matter is to be regarded as an aggregation of molecules in which the attractive force which unites them is reduced to a minimum because the spaces they occupy are relatively great, and that these molecules are therefore in a constant state of rapid motion and bombardment a state of things that is of course greatly enhanced by the applica- tion of heat. It is this bombardment that is the foundation of the pressure or elastic force exercised by gas confined in a vessel at any given temperature and pressure. (See Molecules.) GASES (Diffusion of) See Gases and Diffusion. GASES (Liquefaction of) See Heat. GAS BURNERS See Burners. GAS GENERATORS There are many forms of laboratory gas generators, bottles and flasks properly fitted up being often employed, and particularly the latter when it is necessary to employ the agency of heat. GAS GENERATORS GAS MANTLES 219 GAS GENERATORS (Continued) Kipp's apparatus for the generation of hydrogen disulphide (sulphuretted hydrogen), carbon dioxide, etc., in gaseous form, is of glass, and consists of sections as shown in figure, the upper part, which is re- movable, terminating in a long tube which passes down through the middle one and reaches near the bottom of the lower one. To make hydro- gen disulphide, iron sulphide in small lumps is placed in the glass reservoir B, and concentrated hydrochloric acid poured into A by means of the thistle funnel and tube fitted into its neck until C is filled and the acid rises to some extent into B, where it acts on the iron sulphide, liberating hydrogen disulphide. The gas can now be obtained by opening the cock E, and then it passes out at F. When not required, the cock is shut, and the gas generated in B then exerts pressure on the acid left in it, and forces it down into C and up into A, thus leaving the iron sulphide and the aid out of contact, gas, therefore, ceasing to be generated. When it is desired to use this apparatus for the genera- tion of carbon dioxide, lumps of marble (CaCO 3 ) are placed in B instead of the iron sulphide, and the working is the same. It may also be used for generating hydrogen gas, substituting granulated zinc again for the iron sulphide or the marble, but in this case, it ^is desirable to place around the tube descending from A that is, the annular space between it and the contracted part of the globe B a disc of woven asbestos cloth on which the granulated zinc may rest, to obviate its passage by dropping into the part C. (See also Woulfe's Bottle.) GAS MANTLES of incandescent character are prepared from ramie yarn, artificial silk, and other materials, by impregna- tion with mixtures of thoria and ceria the rare earths which are found in monazite sand and some other minerals. 220 GAS MANTLES GAS PRODUCERS GAS MANTLES (Continued) After impregnation with the necessary chemicals, the mantles are lightly coated with collodion solution to give strength to the texture. The impregnation is ordinarily effected by soaking the mantles in a solution of thorium and cerium nitrates in the proportion of 99 to I, other substances being sometimes introduced for specific reasons, after which, and before coating with collodion, they are dried and ignited to burn off the fibre and cause the deposition of the oxides (thoria and ceria) from the nitrates on the ash skeletons of the mantles. The gas mantle at its lowest efficiency renders it possible to obtain fifteen times the light obtainable from any quantity of gas stripped of its cyclic hydrocarbons. The British output for the year ended October 30, 1920, was 82,322,000. GAS PEODUCEES There are several forms of industrial gas producers (see Producer Gas), but in that form known as the suction gas plant, anthracite is the fuel that is used and this is placed in a cylindrical furnace (producer), air and steam being admitted below the burning fuel. The atmospheric oxygen first combines with the burning carbon to form carbon dioxide, and this, in passing through the red-hot mass, is converted into carbon monoxide. The steam is also decomposed to some extent, forming more carbon monoxide and hydrogen gas, both of which are combustible, and together with the residual nitrogen of the air, constitute the so-called " water gas," having a high calorific value. This is washed and cooled in a scrubber before being sucked in by the piston of the engine. Coke and peat can be employed in the place of an- thracite. Suction gas made as described has an approximate composition as follows, and a calorific value of about 140 B.T.U. per cubic foot : Carbon monoxide -.-%. ... 1 8*6 per cent. Hydrogen ... . i?'6 Methane ... ... ... 1*6 Carbon dioxide ... ... 7*2 Nitrogen ... ... ... 54-4 Oxygen ... ... ... 0-6 lOO'O GASOLINE GASTRIC JUICE 221 GASOLINE (Petrol, Motor Spirit) Used also as a solvent, cleansing agent, in paint-mixing, and making rubber cements ; consisting of petroleum distillate fractions boiling at from 38 to 100 C. (See Petroleum.) GASSING from chlorine in chemical works is not infrequent, and is generally caused by the workmen entering the chambers wherein lime has been chlorinated in course of the manufacture of bleaching-powder, before the chlorine gas has been exhausted, and at other times owing to accidental leakages. It is usual for the workmen to hold rags or a cloth wetted with water or dilute sodium car- bonate in their mouths to prevent injury. In the recent war, gassing attacks by means of a chlorine cloud produced by the use of liquefied chlorine were made, and various other substances were used, including cyanogen chloride (CNC1) (a colourless, poisonous liquid, which boils at 13 C.), chlorinated picric acid and phosgene (carbonyl chloride, COC1 2 ) (which liquefies below +8 C., and yields a gas of very suffocating odour), xylyl bromide and benzyl bromide (with which " tear " shells were at first filled), and later, chloromethyl and trichloromethyl chloroformates highly poisonous bodies. The so-called " mustard gas" was produced by the use of the oily, liquid, dichlorethyl sulphide (CH 2 C1,CH 2 ) 2 S (prepared from ethylene by the action of sulphur mono- chloride), which, although it does not produce any immediate effect on the eyes, brings about most severe inflammation and intractable blisters later, acute pneumonia, and other serious results, due to its hydrolysis within the eye, leading to the formation of hydrochloric acid in the live cells. A number of other chemical compounds, including sulphur trioxide, were also employed. Suitable chemical reagents for neutralizing these various poisons were provided as far as possible, being used in respirators. A solution containing sodium sulphide and soap, used in the form of a fine spray, has been found very effective in purifying the air from certain toxic gases, including chloro- picrin, chlorine, phosgene, methylchloroformates, acrolein, bromoacetone, cyanogen chloride, and benzyl iodide, bromide, and chloride. GASTRIC JUICE contains in 1,000 parts about 994 to 995 parts of water, 5 per cent, of various saline substances (particu- larly sodium chloride), 3 per cent, of pepsin, and a very small quantity of free acid, including hydrochloric acid. It has the power of dissolving albuminous substances taken 222 GASTRIC JUICEGEMS GASTRIC JUICE (Continued) as food, thus producing peptones, so that the food is made assimilable. GAULTHERIA OIL (Oil of Wintergreen) A colourless or slightly red essential oil of sp. gr. 1*175 to 1*185, rotation -0-25 to - i, and boiling-point about 218 C, obtained from the Gaultheria procmnbens, or Canada tea, which grows freely in New Jersey. It exists in all parts of the plant, has a pleasant odour, and contains a substance in the nature of a methyl combination with salicylic acid (C 7 H 6 O 3 ), from which that acid can be prepared, although it is also pro- duced synthetically. It is soluble in alcohol, ether, chloro- form, and carbon disulphide, and is used in perfumery, confectionery, and for flavouring, as also in medicine. GEDDA The name of certain East Indian waxes, stated to con- tain 48 per cent, ceryl alcohol associated with fatty acids, etc. GEL See Colloid. GELATIN An albuminous substance forming an important constituent of many animal tissues, including cartilages, bones, and horn. Commercially, it may be prepared from bones by digesting them in water acidified with hydro- chloric acid, which assists in the separation of the gela- tinous parts from the calcareous parts. In the dry state it is almost colourless or has a slightly yellowish tint. It swells when placed in water and becomes translucent, but does not dissolve to any great extent, although it passes into solution upon heating. Gelatin as prepared from various sources differs slightly in composition, but contains approximately 50 per cent, of carbon, 6-5 to 7 per cent, hydrogen, and from 17-5 to i8 4 per cent, nitrogen. Gelatin is largely employed in the preparation of jellies, foodstuffs, confectionery, adhesives, medicinal capsules, and for other purposes. A solution of even i per cent, gelatinizes on cooling. When dried, it is insoluble in alcohol and ether. (See Albumin, Isinglass, Proteins, Size, and Glue.) GELSEMININA (Gelsemine) (C 22 H 26 N 2 O 3 ) A yellowish-white, crystalline alkaloid, of melting-point 172 C. soluble in alcohol and ether, which forms salts, and has mydriatic properties. It is extracted from the dried rhizome and roots of yellow jasmine (Gelsemium nitidum, etc.), and is imported from the United States. GEMS Precious stones, such as the diamond, ruby, topaz, and emerald. Imitations of them consist of glasses, but the GEMSGERMA NI UM 223 GEMS (Continued) ruby and the sapphire are now produced commercially by the fusion of pure alumina, and are identical in all respects with the natural gems. (See Aluminium.) The colour of the ruby is due to a small content of chromium, as also probably that of the sapphire ; the emerald and aquamarine owe their green tint to the presence of ferrous iron, and are varieties of beryls ; the amethyst and the garnet also owe their colours to ferric iron or manganese, or both. The individual gems are further referred to under their separate names. GENTIAN is the dried root of the Gentiana lutea which grows abundantly in Switzerland, the Tyrol, and the Auvergne. An aqueous infusion is used as a bitter tonic in medicine, a substance named gentianic acid being considered the chief active principle. The root contains a yellow colour- ing matter. GERANIAL See Citral. GERANIOL (C 10 H 18 O) is contained in a number of essential oils, and is the chief constituent of Indian geranium oil, which is used as a substitute for otto of roses. It boils at 230 C., has a sp. gr. of 0-88, and is stereoisomeric with terpineol. (See Citral.) GERANIUM OIL (Rose) Distilled from the herbs Pelargonium radula, P. capitatum, and P. odoratissimum in Algeria and other parts of Africa, is of pale yellow or greenish colour, having geraniol as its chief constituent. It is soluble in alcohol and ether, has a sp. gr. of 0*886 to 0-898, and rotation of -7 to 12. It is used in perfumery. (See Geraniol.) The Turkish Oil (Palmarosa Oil), which comes really from the East Indies, has a sp. gr. of 0-890 to 0-900, and is distilled from the grass of a species of Andropogon. It is very similar to the " rose " oil, and used for the same purposes. Japanese oils, obtained respectively from Pelargonium graveolens, P. radula, and P. denticulatum, grown near Tokyo, and recently examined, showed sp. grs. of 0-9178, 0-9234, and 0-8860, and total geraniol content as follows: 23-1 per cent., 26-3 per cent., and 63-5 per cent., the P. denticulatum variety being, therefore, the most valuable for perfumery. GERMANIUM (Ge) Atomic weight, 72-5 ; sp. gr., 5-46 ; melting-point, about 900 C. A rare element (found in the 224 GERM A NIUMGLA SS GERMANIUM (Continued) minerals argyrodite and canfieldite), of which little is known, and described as both metallic and non-metallic that is, on the borderland. It is of a crystalline character, and is said to combine with the alkaline hydrates forming com- pounds corresponding to silicates. There is an oxide (GeO), a chloride (GeCl 2 ), and a sulphide (GeS). GERMAN SILVER See Alloys. GERMICIDES Chemical preparations that kill bacteria and other germs. GERMS See Bacteria and Microbes. GHEE A clarified butter made from buffalo milk, with or without added cow's milk, from which moisture, casein, and other constituents, except the fat, have been removed. It is prepared in Somaliland and India, and is used both in cooking and as a food. It has a melting-point varying from 34 to 37*3 C., a saponification value of from 227 to 238, and an average Reichert-Wollny value of 34*5. GIN is spirit distilled from fermented wort of malted barley, and flavoured with juniper berries by distillation or otherwise. GINGER is the root of Zingiber officinale, which grows in India and other tropical places, and contains a number of chemical substances, including about 1*5 per cent, of a volatile oil, " gingerol," which is said to contain some terpenes and a mixture of two homologous bodies, C 17 H 2 gO 4 and C 18 H 28 O 4 , also another substance called zingerone (CuH^Og). Apart from its use as a spice, it is used as an aromatic addition to griping medicines. " Gingerol " is used in flavouring and in compounding liqueurs. GINGER OIL Obtained by distillation from the rhizome of Zingiber officinale, is a yellowish, aromatic oil of burning taste, soluble in alcohol and ether, with a sp. gr. of about o f 88, and is used for flavouring purposes. GINGER-GRASS OIL is distilled from the grass of a species of Andropogon, somewhat resembling geranium oil in character, and is used in perfumery. GLACIAL ACETIC ACID See Acetic Acid. GLASS A fused mixture of silicates of potassium or sodium with one or more other silicates which are insoluble in water, such as silicate of calcium, magnesium, etc., the silicates of the alkalies alone being soluble in water. In practice, GLASS 225 GLASS (Continued) ground quartz or flint or clean sand, mixed with potassium or sodium carbonate and the other ingredients, are fritted together in an oven or furnace, by which means the silica constituting the quartz or sand enters into combination with the bases, thus forming glass. It is of importance that the sand should be of high purity (98 to 100 per cent. SiO 2 ) and free from iron oxides, or nearly so. There are many and very great varieties of glass, differ- ing from each other in their respective compositions, qualities, and uses. When the mixture used (as for plate- glass-making) consists only of sodium carbonate, calcium carbonate, and sand, the two carbonates first of all fuse together, and then at a higher temperature they are decom- posed by the silica (of the sand), the two bases combining therewith, whilst carbon dioxide is evolved. Window Glass is made by fusion from a mixture of sand, sodium carbonate or sodium sulphate, and limestone in fire- clay pots. Bohemian Glass is made from pure potassium carbonate and powdered quartz, and is not so fusible as window glass. Flint and Lead Glass are made from ground flint, lead oxide, and potassium carbonate, with or without some added nitre, and is very fusible ; the ordinary household glass articles being made from this quality. Bottle Glass of green colour is made of silicates of sodium, calcium, and aluminium, the colouring being supplied by oxide of iron. To impart other colours, other metallic oxides are used, that of manganese giving a purple tint, cobalt oxide a blue colour, copper oxide a ruby red ; glasses free from heavy metals are coloured yellow by sulphur; to strongly alkaline glasses selenium gives a chestnut-brown colour ; tellurium can be used to give a purple-red and in some other cases a blue colouration ; chromium oxide gives greens or reds; and so on. Arsenious oxide is used in making many qualities of glass amongst other purposes to correct the green tint which traces of iron would otherwise give to it, by oxidizing it from a ferrous state into a ferric state. For chemical apparatus, a soda-lime glass is preferred for the most part, although the potash-lime glass is superior when the articles to be made should be hard or difficult to 15 226 GLA SSGLA SS-B LO WING GLASS (Continued) fuse as, for instance, glass combustion tubing used in making organic analyses. Up to the time of the recent war, Thuringia and Bohemia enjoyed almost a monopoly of this glass industry ; but as a result of investigations conducted by British chemists during the war, working formulae or recipes for a number of qualities for chemical and other scientific purposes have been successfully introduced to manufacturers in this country for which we were previously entirely dependent upon those and German supplies. One of the best of these is a zinc-aluminium-borosilicate quality. The analysis of a Jena glass beaker gave the following composition : SiO 2 , 64-66 per cent. ; A1 2 O 3 , 674 per cent. ; ZnO, 10-12 per cent. ; CaO, 0*08 per cent. ; MgO, 0-13 per cent. ; Na 2 O, 7-21 per cent. ; B 2 O 3 , 11-14 per cent. ; Fe 2 O 3 , o'io per cent. ; the salient components being the A1 2 O 3 , ZnO, B 2 O 3 , the silica, and the alkali. Some published analyses of glass are as below : Plate. Window. Lime Flint. Lead Flint. Bohemian. Per Per Per Per Per Cent. Cent. Cent. Cent. Cent. Si0 2 71 71 74 54 71 CaO J 3 II 10 PbO 35 Na 2 K 2 Al 2 O 3 and Fe 2 O 3 ... H I tO 2 J 5 I tO 2 19 II 2-5 12-5 9 The tests of good glasses for chemical use include the action of boiling water, boiling water under pressure (autoclave), and the action of acids and alkalies. Fused Silica or Quartz Glass of opaque and transparent characters is now largely used in the construction of chemical apparatus, as it only melts at about the same temperature as platinum, and is very resistant to the action of chemicals. Moreover, it is not liable to breakage by sudden changes of temperature. (See also Porcelain.) GLASS-BLOWING An art that can only be acquired by practice. Suppose it is desired to make a sealed tube with a bulb at one end, a piece of glass tube of the desired size GLASS-BLOWING 227 GLASS-BLOWING (Continued) and length say ~ inch diameter and 4 or 5 inches in length is taken, and one end placed in a Bunsen or blow- pipe flame until the glass softens sufficiently to mass together, close up, and become solid to the extent of about i inch. (See Blow-pipe.) Whilst still red-hot and soft, the mouth should be applied to the open end, turning the tube round in the fingers, and meantime blowing with enough pressure to swell out the molten glass. It may be neces- sary, and often is so, to reheat the blown-out part and repeat the blowing until a bulb of the right size and shape is obtained. Bulb-tubes thus prepared are useful for observing the behaviour of solid chemical substances placed in them for that purpose when heat is applied. The conveyance to the bulb-tube of the substance to be examined can be easily effected by the use of a sharply channelled slip of paper. Iodine will be seen to volatilize, and give off fumes of its own colour, and to recondense to the solid state in the upper (cooler) part of the tube. Sulphur can be seen to melt and pass through the stages described under that heading, including sublimation and recondensation. Mercury can be sublimed and seen to condense on the upper cool part of the tube ; so also ammonium chloride. Lead filings can be melted in the bulb. White lead is decomposed, carbon dioxide being given off as gas, and yellow litharge being left behind in the tube. Glass T-pieces can be made with a little practice, and are often wanted in the laboratory. Take a piece of glass tube of the desired length, and plug one end with a small boring of cork ; then hold it in the flame of a blow-pipe so that a fine tongue of flame impinges upon and heats the tube in one spot only, near the middle ; and when it is observed to be red-hot, remove the tube from the flame and place the open end quickly in the mouth. Upon blowing, the molten part will become distended into the shape of a swelling or balloon, so thin that it can easily be broken, thus leaving a hole in the tube, the edges of which can be rounded off with a file. Next, take another piece of glass tube and blow a bulb at one end as previously described, taking care, however, in this case to blow the bulb as large, and therefore as thin, as possible. This bulb is then to be broken and the edges rounded off as in the other case with a file, when it remains to join the two pieces together. We have then the one tube with a hole 228 GLASS BLOWING GLOBULINS GLASS-BLOWING (Continued) in its centre, and the other tube with one end provided with a sort of lip roughly fitting the hole as to size. The flame of the blow-pipe should now be applied to both these parts, and when sufficiently softened by the heat they can be joined together (welded) in the flame. GLASS TUBES are of various diameters, and can be connected together when desired by rubber tubing. The ordinary size is about 5 millimetres outside diameter. They can be bent to any desired shape by heating (meantime turning them round), until softened, in the flame of a fish-tail gas burner, and then applying pressure by the hands until the desired bend or angle is reached. A glass tube can be drawn out to a smaller dimension or to a fine point when heated, as, for example, when it is desired to make the longer pointed tube for use in a wash-bottle. When the tube so drawn out has cooled, it is cut at the drawn-out part. During this heating, the tube becomes covered with deposited soot (due to the imperfect combustion of the carbon constituents of the gas), and it is best to leave this on the glass until it is cold, as by so doing the cooling (annealing) is prolonged and there is consequently less liability to fracture. To cut a glass tube, place flat on the bench, and then with the edge of a triangular file make a scratch where it is to be cut. Upon grasping the tube firmly in both hands and application of gentle pressure, it should break evenly across. When the tube is thick or the diameter greater, several file markings should be made in the same circum- ferential ring, or the filings should be made deeper. The rough edges of glass tubes can be ground off with a flat file or rounded off evenly by softening in the edge of a Bunsen flame. GLAUBERITE A crystalline native double sulphate of sodium and calcium (Na 2 Ca(SO 4 ) 2 ), occurring in New Castile, Arizona, New Mexico, Bavaria, at Vic (France), and at Tarapaca in Peru. GLAUBER'S SALTS Sodium sulphate (Na 2 SO 4 ,ioH 2 O). GLAZES Fusible mixtures of felspar and other substances used in the ceramic industries. (See Porcelain and Refractories.) GLOBULINS A class of proteins insoluble in water but soluble in a dilute solution of salt, including globulin from the crystalline lens of the eye, and fibrin of blood. (See Proteins.) GL UCIN UMGL UCOSE 229 GLUCINUM (Gl) or BERYLLIUM atomic weight, o/i ; sp. gr., about i'75 to i'85; melting-point, 1,280 C. is found in nature in a number of minerals, including the beryl (a double silicate of glucinum and aluminium). It is a steel-grey, fairly malleable metal resembling magnesium, which, when strongly heated, is converted into oxide (G1O), and when in a pulverulent form takes fire. A white crystalline chloride (G1C1 2 ) is known, and the metal itself is obtained by heating metallic sodium in the vapour of this chloride, which is volatile. The metal can also be obtained by the electrolysis of the double fluoride of glucinum and potas- sium. It is soluble in dilute acids, and forms an alloy with copper. Many of its compounds, including fluorides (GIF and G1F 2 ), chloride (G1C1 2 ), bromide, iodide, sulphide, carbide, sulphates, nitrate, etc., in general characters re- semble the aluminium compounds. GLUCOSE (Dextrose) There are a number of sugar-like bodies termed glucoses, of which the best-known member is grape sugar, or dextrose (C 6 H 12 O 6 ,H 2 O). It is con- tained in honey and in most sweet fruits, and can be prepared from sucrose (cane sugar) or starch by the action of dilute acids (hydrolysis). Commercial glucose is chiefly made by the prolonged action of dilute sulphuric acid upon maize or other starch, and is stated to be a mixture of real glucose with varying proportions of dextrin and maltose. The sulphuric acid is removed by chemical means and the syrup evaporated in vacuum pans until semi-solid, after which it can be run into moulds, constituting when cold, a hard opaque substance, white or slightly yellow in colour, used extensively in the confec- tionery, jam, and syrup trades. Glucose in the nature of imperfectly converted starch and containing up to 50 or more per cent, of inverted products other than glucose, is made largely for use by brewers and in manufacturing con- fectionery, wines, etc. When cane sugar is hydrolyzed by acid treatment it is converted into so-called " invert sugar " that is, a mixture of glucose with fructose, and it has been shown that these two substances and mannose another variety of glucose obtained from mannitol are partially and mutually trans- formable. Inverted sugar is uncrystallizable. When glucose is heated to 150 to 155 C. under reduced pressure, it loses water and is converted into the anhydride glucosane (CgH^Og), which can be obtained in a deli- quescent crystalline form, melting at 108 to 109 C., 2 3 o GL UCOSE-GL U CO SIDES GLUCOSE (Continued) and, when heated with water, is retransformed into glucose. By heating cotton cellulose in a distilling apparatus under a pressure of 10 to 15 mm. it decomposes at 210 C., and an oil equal in weight to 45 per cent, of the cellulose, distils over and subsequently solidifies with a composition represented by C 6 H 10 O 5 , and supposed to be the anhydride named laevo-glucosan. Quite recently, it has been de- finitely proved that crystalline glucose (melting-point 145 F.) can be obtained from normal cotton cellulose. (See Dextrose and Invertase.) GLUCOSIDES A class of organic compounds found present in many vegetable tissues, which are resolved by hydrolysis (as effected by the action of enzymes, acids, or alkalies) into a sugar (usually glucose) and other simpler organic substances. Amygdalin (C 20 H 27 NO 11 )is a white, crystalline glucoside found present in the bitter almond, and is decomposed in the presence of water by the action of an enzyme (emulsin) contained in the tissue of the almond as follows : C 20 H 27 NO n + aH 2 O = C 7 H 6 O (benzaldehyde) + HCN (hydrocyanic acid) + 2C 6 H 12 O 6 (glucose). Other glucosides are Arbutin (C 12 H 1 gO 7 ), from the leaves of the bear-berry, resolved by emulsin into glucose and hydroquinone. Phloridzin (C 21 H 24 O 10 ) A constituent of the root bark of apple, pear, cherry, and plum trees. Salicin (C 13 H 18 O 7 ) Present in the bark of the willow and in poplar buds. Coniferin (C^H^Og^HaO) Contained in the cambium sap of various fir-trees. Indican From which indigo is made. (See Indigo.) Hederin (C 64 H 104 O 19 ) From ivy. Hesperidin (C 22 H 26 O 12 ) A constituent of unripe oranges. ^Esculin (C 15 H 16 O 9 ) Contained in the horse-chestnut bark. Digitonin, Digitalin, and Tannin. Most of the glucosides are hydrolyzed by emulsin in particular, but are accompanied in the plant tissues contain- ing them, by an enzyme which is also capable of effecting their hydrolysis. (See Hydrolysis.) GLUE GLYCERINE 231 GLUE A gelatinous body made from the parings of hides, the pith of horns, and other animal offal, by boiling them with water. The liquid thus prepared, is afterwards poured into frames or moulds, in which it sets to a solid mass. Fish glue is made from the bony structures of the heads of fishes. It is largely used for making adhesives, finishing textiles, in the felt-hat trade, etc. A good glue should not attract moisture, and should be capable of absorbing six to seven times its own weight of water without liquefying. (See Isinglass.) GLUE (Liquid) is made by treating ordinary glue with acetic or hydrochloric acid, wnen it loses its gelatinizing property, but retains its adhesiveness. GLUTEN or VEGETABLE ALBUMEN The albuminoid or protein part of wheat flour, amounting to from 10 to 15 per cent, in the best qualities, and in inferior grades to from 8 to 9 per cent. It is that part of the flour which when made into a paste and washed with water forms the tenacious part as distinct from that portion which dis- solves in the water and the starch which goes into suspen- sion in the water. It is soluble in alkalies and in strong acetic acid. GLYCERIC ACID (C 3 H 6 O 4 ) A thickish liquid resulting from the oxidation of glycerol (glycerine) by nitric acid : it enters into combination with the alkalies and other bases, forming salts known as glycerates. GLYCEEIDES Esters of glycerol (glycerine) as contained in fats and many oils. (See Esters and Fats.) GLYCERINE or GLYCEROL (C 3 H 8 O 3 ) A syrupy, colourless, and odourless liquid of a somewhat sweet taste, and sp. gr. 1-27. It is soluble in water and alcohol, solidifies to a crystalline condition when exposed to a sufficiently low temperature (below 17 C.), and boils at 290 C. It is chemically described as a trihydric alcohol (C 3 H 5 (OH) 3 ) and is a product of the decomposition (saponification) of fats and many oils, being practically manufactured on a large scale from the spent lyes resulting from soap-making. The alkali used for soap-making combines with the fatty acids to make soaps, while the glycerine passes into solution and is recovered from the lyes. It is also produced by distilling fats in superheated steam, by which process they are also hydrolyzed, the glycerine passing over with the steam, leaving the fatty acids behind ; or the fats can be hydrolyzed by heating in water to which a small quantity of sulphuric acid has been added, and with 232 GLYCERINE GLYCINE GLYCERINE (Continued) or without the addition of other catalytic agents. In such case, the fatty acids rise and float on the top of the liquid which contains the glycerine and from which it can be easily recovered. Glycerine has been obtained to some considerable extent in Germany, and more recently in the United States of America, from molasses and sugar, by a process of fermen- tation with a selected yeast (S. ellipsoideus) in an alkaline medium. Commercial sucrose, dextrose, laevulose, or invert sugar can be fermented with yeast in the presence of one or more inorganic or organic substances of alkaline reaction, such as disodium phosphate, sodium or ammonium carbonate, or sodium bicarbonate, with or without catalysts such as manganese or iron sulphate. The fermentation is preferably conducted in the presence of sodium sulphite together with a small quantity of a hydrosulphite or sulph- oxylate, and the yeast can be regenerated by a purifying fermentation in presence of dilute acid and used over again together with a surplus yield, which can be employed for baking or fodder. In this way the yield of glycerine amounts to from 23 to 367 per cent, of the sugar. Glycerine is largely used in the manufacture of nitro- glycerine and other explosives, in the preparation of perfumes, cosmetics, printing-ink rollers, liqueurs, fruit preservatives, blacking, and (when mixed with 5 or 6 parts water) as a lotion for chapped and sunburnt skins. It can be distilled in vacuo or in the presence of steam without decomposition, but it undergoes decomposition when heated in the air. Glycerine never freezes at atmospheric temperatures, and is sometimes used, therefore, as a lubricant for delicate machinery. GLYCEROPHOSPHORIC ACID (C 3 H 9 PO 6 ) (sp. gr. 1-125) A cleavage liquid product from complicated substances con- tained in the yolks of egg and brain matter. It is soluble in water and alcohol ; forms a characteristic compound with lead (C 3 H 7 PbPO 6 ) and is an ester of glycerol (glycerine). GLYCINE (Glycocoll) or AMINO-ACETIC ACID (C 2 H 5 NO 2 ) A white, crystalline substance, which melts at about 234 C., soluble in water and of sweet taste, which behaves both like a base and an acid forming salts that is to say, with both acids and bases. It can be prepared chemi- cally by several methods, but it is especially interesting considered as a derivative of wool and silk and as a GLYCINEGOLD 233 GLYCINE (Continued) product of the hydrolysis of certain albuminous bodies, because it is believed that a mixture of amino- acids, together with sufficient amounts of fat, starch, sugar, and the necessary saline bodies, will maintain life without the use of proteins. (See Amino-acids, Foods, and Vitamines.) GLYCOGEN (CgH 10 O 5 ) An amylaceous or dextrin-like sub- stance contained in the liver and placenta of animals. It combines with water to form a gummy body, and its aqueous solution rotates polarized light to the right four times as much as dextrose. When boiled with dilute acids it is changed into maltose. GLYCOLLIC ACID (C 2 H 4 O 3 ) occurs naturally in the juice of the sugar-cane, in unripe grapes and the leaves of the wild vine, and may be prepared in a number of ways, including the oxidation of glycol. It is a colourless, crystalline, deliquescent substance, which melts at 78 C., and is soluble in water and alcohol. By the action of nitric acid it is converted into oxalic acid. GLYCOLS See Alcohols. GLYCURONIC ACID (C 6 H 10 O 7 ) A product obtained from saccharic acid by reduction with sodium amalgam. GNEISS A more or less laminated mineral of granite character containing mica. GOA POWDER See Chrysophanic Acid. GOLD (Aurum, Au) Atomic weight, 197; sp. gr., 19*3; melt- ing-point, 1,063 C. Gold is widely distributed in nature and is found for the most part in the free or metallic condition in quartz veins and alluvial deposits resulting from the gradual disintegration of gold-bearing (older sedimentary or plutonic) rocks. It is extracted from quartz by crushing and amalgamation with mercury, and from alluvial deposits by mechanical washing with water, the water carrying away the lighter associated substances and leaving the heavier gold behind. When the amalgam process is used, the gold is obtained from the amalgam by distilling off the mercury, the gold being left behind. There are other methods of extracting gold from its ores, in one of which potassium cyanide (KCN) is. used on a very large scale. The crushed ore containing gold in a finely divided condition is treated with a solution of the potassium cyanide containing from J to i per cent, while 234 GOLD GOLD (Continued) freely exposed to the air. This dissolves the gold, which is afterwards precipitated from the solution by means of metallic zinc or by electrolytic action, using lead-foil cath- odes for that purpose, and subsequently fused. When zinc is used, the solution containing the gold in the form of a double cyanide of potassium and gold under- goes chemical change as follows : 2KAu(CN) 2 + Zn = K 2 Zn(CN) 4 + 2Au ; that is to say, the zinc replaces the gold in the double cyanide and the gold is set free. Gold is comparatively soft, yellow in colour, and the most malleable and ductile of all metals, admitting of being .beaten into an extremely fine form of leaf, which is used for gilding and other purposes. It can be beaten out into sheets so thin that 280,000 are required to make one inch in thickness. Gold is not attacked by acids, with the exception of aqua regia (nitrohydrochloric acid), in which it dissolves, forming auric chloride (AuCl 3 ). Alloyed with copper and silver, it is largely used for coinage and other purposes. Pure gold is described as 24-carat gold, whilst i8-carat gold consists really of 18 parts of gold and 6 parts copper or silver. In this country the legal standard is 22-carat gold, and English gold coin consists of ii parts gold and i part copper. It is also used in dentistry and the preparation of amalgams. Electro-gilding of other metals, is carried out by using a solution of the double cyanide of gold and potassium (AuK(CN) 2 ). (See Electricity.) Aurous oxide or gold suboxide has the formula Au 2 O, and is insoluble in water. Auric or gold oxide (Au 2 O 3 ) is a brown powder, which is also insoluble in water, combines with ammonia to form a substance of indefinite composition named fulminating gold, which explodes easily when heated to 100 C. or struck with a hammer. There are two chlorides, AuCl and AuCl 3 , both of which are soluble in water, the latter being the more important. It is formed when gold is dissolved in aqua regia, and can be obtained in yellowish-red crystals having the com- position AuCl 3 ,2H 2 O, which lose their water of crystalliza- tion upon heating, and change to a brown mass. The trichloride is used in photography and gold- plating. When a neutral solution is, added to a dilute solution of GOLDGRA VITA TION 235 GOLD (Continued} a mixture of the two chlorides of tin, a purple colour is produced known as " purple of cassius," which is used in the manufacture of ruby glass and colouring enamels, etc. The double chloride, gold-potassium chloride (AuCl 3 . KC1,2H 2 O), is a yellow, crystalline salt used in painting porcelain and glass. GOLDBEATEKS' SKIN Peritoneal membrane from the intes- tinal tube of the ox and other animals, soaked in a weak solution of potash; then, after washing, stretched and beaten out with a hammer, and finally treated so that it cannot undergo putrefaction. GONIOMETER An instrument for measuring the angles of crystals. GOOCH CRUCIBLE See Crucibles. GOULARD WATER A very dilute solution of lead acetate used for bathing weak eyes, etc. GRAINS OF PARADISE (Melleguetta Pepper) The fruit of certain zingiberaceous plants (Amomum melleguetta) grown in Ceylon and on the western coast of Africa ; used as a condiment and in medicine. GRANITE Rocks of felspar and mica in a mass of quartz, often associated with other minerals. GRAPE SUGAR or GLUCOSE See Dextrose, Glucose, Sugars, and Carbohydrates. GRAPHITE See Carbon. GRAVITATION The science of gravitation is said to have changed physical astronomy into a mechanism of the heavens. Kepler discovered the mathematical laws by which the planets are balanced in space, and according to the law of gravitation weight is determined, the weight of any sub- stance being the measure of its attraction by the earth. In other words, weight is defined as an acquired property of matter produced by an attractive force emanating from the centre of the earth. Weight diminishes with distance from the earth, so that a mass of lead weighing 1,000 Ib. at sea-level weighs 2 Ib. less at a height of four miles. The intensity of gravitation is inversely as the square of the distance of the gravitating body. 236 GRA VITA TIONG UA I A C- WOOD OIL GRAVITATION (Continued) Some forty-two theories have been propounded to account for gravitation, and among these, adhesion (as between two clean plates of metal), cohesion, and capillary attraction, together with gravitation, have all been viewed in common as manifestations of magnetic force ; but while no fact has at present been found which is necessary for the substan- tiation of any of them, it is thought that the further study of atoms and their structure will throw light upon the true nature of gravitation. The fall of an apple from tree to earth, the tidal waves, the courses of the planets round the sun, and the move- ments of all the heavenly bodies, are attributed to gravitation. GRAVITIES See Densities, Specific Gravity, and Hydro- meter. GREENOCKITE See Cadmium. GREEN OIL A heavy, crude, creosote oil distilled from coal tar. (See Coal.) GREEN VITRIOL (Copperas) Common name for ferrous sulphate. (See Iron.) GREY ANTIMONY ORE (Stibnite) See Antimony. GRINDSTONE A highly cemented, tough, natural sandstone. GROUND-NUT OIL (see Arachis Oil) Ground-nuts are now cultivated in China to a considerable extent. GUAIACOL C-H 8 O 2 or C 6 H 4 (OH)(OCH 3 ) is a phenolic compound, found present in beechwood tar, and is pro- duced along with other substances by the dry distillation of guaiacum resin. (See Guaiacum.) It is a colourless, re- fractive, inflammable, oily body of peculiar faint odour, reminding of creosote ; of sp. gr. 1*1395, soluble in alcohol, and used in medicine. GUAIACOL CARBONATE (C 15 H 14 O 5 or (C 6 H 4 OCH 3 ) 2 ,CO 3 ), a white, crystalline powder soluble in alcohol and ether, is used as a non-irritating preparation in the treatment of phthisis, diarrhoea, and typhoid fever, acting as an anti- pyretic and antiseptic. GUAIAC-WOOD OIL A thick, viscid oil, apt to become crystalline, distilled from the wood of some species of guaiacum, known as " balsam wood " in South America. It is soluble in alcohol and ether, has a sp. gr. of about 0*96 to 0*98, with optical rotation - 6 to 7, and is used in perfumery. GUAIACUMGUMS 237 GUAIACUM A resinous exudation from incisions made in the stems of the Guajacum officinale, a tree which grows in Jamaica and other West Indian islands. It is soluble in alcohol, acetone, and ether, acts as a mild laxative and diuretic, and is used in the form of lozenges and pastilles for throat troubles, also in varnish-making. An optically active substance named guaiaretic acid (C 2 pH 24 O 4 ) has been isolated from the resin. (See Lignum Vitae.) GUANO Excrement of sea-fowl from islands near the coast of Peru and Chili, consisting largely of calcium phosphate, and used as a fertiliser. (See Coprolites.) GUMS The generic name of a number of vegetable, gummy products that is to say, more or less sticky some of which are of the nature of carbohydrates. Gum Accroides (Black-boy Gum) A resin from xan- thorrhea-trees, grown in Australia ; soluble in alcohol, and used in varnish-making. Gum Ammoniacum is really a natural resin obtained from the Dorema ammoniacum. Gum Anime See Anime. Gum Arabic (Acacia) is the dried juice from the bark of various species of Acacia which flourish in Arabia, Egypt, and Senegambia. It dissolves slowly in water, and consists mainly of a mixture of alkali arabinates, the arabinic acid comprising a combination of a simpler acid named arabic acid in association with two sugar-like bodies named arabinose and galactose. The formula as follows, generally represents the combination named arabinic acid 2(C 10 H 16 8 ), 4(C 12 H 20 10 ) C 2 3H 30 18 . Arabinose. Galactose. Acid Group. It is used not only as an adhesive, but also in the prepara- tion of a number of pharmaceutical and chemical emulsions; for thickening ink and blacking, and in calico printing. Gum Benzoin See Benzoin Gum. Gum Cowrie See Kauri. Gum Copal See Copal Gum. Gum Dammar See Dammara resin. Gum Elemi is really a resinous East and West Indian product obtained from various terebinthinous trees, includ- ing the Amyris elemifera (Dutch Settlements), and is used in making varnishes and lacquer. Gum Kauri See Kauri. 238 G UMSG UTTA -PERCH A GUMS (Continued) Gum Manila A copal variety of resin from the Philip- pines, of sp. gr. i -06, and melting at from 230 to 260 C. ; soluble in alcohol and ether, and used in making paints and varnishes. Gum Mastic See Mastic. Gum Sandarach See Sandarach. Gum Senegal .is obtained from a species of acacia in Senegal and makes a stronger mucilage than gum arabic (acacia). It is used for thickening the colours and mor- dants used by calico printers. Gum Thus is really a resin and is not soluble in water. (See Turpentine.) Gum Tragacanth is an exudation from the Astragalus vevus tree which grows in Armenia and Persia. It swells up in water and half of it is soluble, and the other part, consisting of starch, etc., also dissolves or mostly so upon boiling. It contains about 53*3 per cent, arabin and is used in medicine, by pharmacists for making emulsions, and in calico print- ing. The cherry-tree furnishes a somewhat similar gum. British Gum (Dextrine) is prepared from starch by the action of a small quantity of acid at a temperature of about 150 C. The action of malt extract upon starch also produces dextrine (C 6 H 10 Og) in association with dextrose. (See also Mucilage and Resins.) Yacca Gum See Yacca. GUN-COTTON (Pyroxilin) is probably a hexanitrated cellulose, whereas collodion is a tetranitrate of cellulose. (See Explosives.) GUN-METAL See Copper. GUNPOWDER See Explosives. GUTTA-PERCHA A natural, dark, hardened juice of the Sapotacea or gutta-percha trees (Isonarda pevcha or Isonarda gutta) which grow in Borneo, Brazil, Malay, Singapore, Ceylon, etc. It exudes from incisions made in the bark, and in a pure state is white, insoluble in alcohol but soluble in carbon disulphide, turpentine, and ether. It becomes soft and impressionable when warmed in hot water, melts at about 120 C., and is largely used as an insulating material for covering cables and electric wires, as a covering for golf balls, in dentistry ; for making bottles, funnels, G UTTA -PERCH A HA RTSHORN 239 GUTTA-PERCHA (Continued) jugs, taps, valves, and many other articles. Gutta-percha is a hydrocarbon, having near chemical relationship to turpentine and rubber. GYPSUM See Calcium. HABEE PROCESS See Nitrogen Fixation. H^BMATINE The red colouring matter of the blood is haemo- globin, a body of very complicated constitution consist- ing of haematine and albuminous matters, and when this is dissociated it yields haematine (C 32 H 32 FeN 4 O 6 or C 34 H 34 FeN 4 O 5 ), which appears to be chemically related to chlorophyll. (See Chlorophyll and Respiration.) HEMATITE Iron ore of many varieties. (See Iron.) "HAILCRIS" A British white glass for making miners' lamps, water-tight fittings, lamp globes, etc. " HAILUXO " GLASS A British make claimed to be equal to the best Jena glass used for making miners' glasses and chemical apparatus, of high heat-resisting quality. HAIR Consists of coalesced horny cells of a gelatinous character containing from 075 to 2 per cent, of mineral salts. HAIR-SALT A natural aluminium sulphate, of fibrous for- mation. (See Aluminium.) HALIDES Metallic and non-metallic binary combinations of the halogens such as sodium chloride (NaCl) and silicon tetrachloride (SiCl 4 ). HALOGENS The group of chemical elements consisting of chlorine, iodine, bromine, and fluorine, so named because they form compounds with metals analogous to sea-salt (sodium chloride). In their general character, they resemble each other, and by combination with hydrogen they form respectively hydrochloric, hydriodic, hydrobromic, and hydrofluoric acid (HC1, HI, HB, and HF). HALOGEN DERIVATES of organic bodies are formed by the replacement, for example, of hydroxyl (HO) by a halogen ; thus ethyl alcohol by the action of hydrobromic acid is converted into ethyl bromide C 2 H 6 OH + HBr = C 2 H 5 Br + H 2 O. HALOIDS Salts composed of halogen elements with metals, such as sodium chloride and potassium iodide. HARTSHORN An old name for crude ammonium carbonate as originally obtained by distillation of horn shavings. 240 HA USMA NNITEHEA T HAUSMANNITE A mineral-red manganese oxide (Mn 3 O 4 ). HEAT The view taken by Sir Isaac Newton, and still generally accepted, concerning the nature of heat, is that it has its origin in the internal motions of the particles of bodies that is to say, movements or vibrations caused by the exercise of energy. Just as the sun is the chief source of light, so also it is the chief source of heat. Heat can be produced by friction, as is experienced in the use of machinery, when the parts of metal rubbing against each other are known to become very hot. An indefinitely large amount of heat can be generated by subjecting a mass of brass to friction, and this is illustrated by the great heat that is produced in the boring of metals. As another instance, it may be stated that, when two pieces of ice are rubbed together, sufficient heat is pro- duced to melt the ice. In all chemical interactions or changes, heat is either given out or disappears. When quicklime is mixed with water (slaked) it combines therewith, forming a hydroxide, and considerable heat is developed, as evidenced by the generation of steam. In most cases, there is an evolution of heat, but in others it is necessary to apply heat to bring about the desired chemical change. Compounds in the formation of which hydrochloric acid, for example heat is developed, are termed exothermic, and those in which heat disappears carbon disulphide, for example are styled endothermic in character. The heat of the human body is produced by the chemical changes that are always going on in it during life. Light can be changed into heat, and heat has a definite mechanical equivalent. Electricity can also be converted into heat and light, as evidenced by the ordinary electric lamps when in use for lighting purposes, which then become hot. According to prevalent ideas, an electric current produces heat in a conductor because the drift- energy of the electrons is to some extent converted into irregular motion energy by their collision with the atoms of the conductor. The same change is utilized in a larger degree in the construction of electric radiators (for warming) and electrical furnaces. When solid, liquid, or gaseous substances are heated, they for the most part enlarge or expand, and when cooled they contract.* The wheelwright makes use of this know- * Ice may be very much colder than the surrounding water, but it floats. Water has a maximum density at 4 C., but if cooled below or heated above this temperature, it expands ; and but for this, in case HEAT 241 HEAT (Continued) ledge in affixing iron tyres to wheels, by placing them round the wheels when in a very heated condition, so that upon cooling they clamp by contraction and hold tight to the wooden rims. But, on the other hand, some metals and alloys expand at the moment of setting, and thus give a sharp casting, whereas others contract at the moment of setting and in consequence give a bad casting. Many solid substances, such as sulphur, camphor, naph- thalene, and iodine, can be sublimated by heat that is to say, they can be converted into the state of vapour, and when the vapour is cooled, the substance is redeposited in the solid form a sort of dry distillation. Again, many liquid bodies, such as water, can be distilled i.e., boiled and thereby converted into vapour, and when the vapours are cooled again, they condense once more into the original liquid forms. Ether, alcohol, turpentine, and many other liquids, can be distilled in this way, and the process is often used for purifying the substances employed from associated impurities. The temperatures at which liquids boil or become vaporized are known as their boiling-points, and these are registered by thermometers. The temperature at which solid or metallic bodies melt are known respectively as their melting or fusing points. Ether boils at 35-6 C. ; alcohol at 78-4 C. ; water at 100 C. ; turpentine at 160 C. ; and mercury at about 350 C. Temperatures are usually determined in this country according to two scales, but chemists for the most part use ;what is called the Centigrade or C. scale ; the other is known as the Fahrenheit or F. In Russia, Italy, and Austria there is still another scale, known as the Reaumur or R. On the Centigrade scale, the freezing-point of water is regarded as zero (p), and the boiling-point is 100 ; whereas on the Fahrenheit scale, the freezing-point is 32, and the boiling-point is 212. To convert a Centigrade reading into a Fahrenheit read- ing, multiply by 9, divide by 5, and then add 32. To convert a Fahrenheit reading into a Centigrade reading subtract 32, multiply by 5 and divide by 9. of great cold, our lakes and rivers might become frozen solid to the bottom. If water had not this peculiar property our climate would be of arctic character and a large part of the world would be unin- habitable. 16 242 HEAT HEAT (Continued) SOME NOTABLE TEMPERATURES. Centigrade. Fahrenheit. Theoretical zero of temperature - 273 - 459^4 Mercury freezing-point ... -38-8 -37-84 Freezing-point of water ... o 32 Mean atmospheric temperature I 5'5 60 Blood heat... ... ... 36-9 98-4 Boiling-point of water ... 100 212 Mercury boiling-point ... 35 662 Pyrites burners ... ... 4oo-5oo 752-932 Red heat just visible in the dark 526 979 Gas producers ... 900-! 300 i652- Reverberatory furnaces 9oo-i4oo i6^2- Kilns for various burnings 900- 1600 1652 -2912 Coke oven (chambers) ... 1100 Deep orange heat ... ... 1100 2012 Frit kilns ... ... noo-i4oo 2oi2-2552 Steel melting-point ... ... 1350 2462 Glass-furnace heat .. ... 1375 2 57 White heat... ... ... 1500 2732 Steel melting (in crucibles) ... 1500 2732 Cast-iron melting-point ... 1530 2786 Open hearth furnace ... 1600 2912 Blast-furnace heat ... ... 1930 3506 Oxy-hydrogen flame ... ... 2800 57 2 Electric furnace ... ... 3600 6512 Arc lamp ... ... ... 4000 7032 In the Reaumur scale, the interval between the freezing and the boiling points of water is divided into 80 instead of 100 as in the Centigrade scale, so that in this case, while the freezing-point is o, the boiling-point of water is 80. To convert Centigrade readings into Reaumur readings, multiply by 4 and divide by 5 ; and to convert Fahrenheit readings into Reaumur readings, subtract 32, multiply by 4 and divide by 9. A substance is said to be a good conductor of heat when heat is easily transmitted by or through it. For instance, if a copper or iron wire be held by the hand and the other end placed in the flame of a lamp or candle, the heat is quickly conducted from that end to the one held in the hand and can be felt. A slab of marble or metal feels colder to the hand than a HEAT 243 HEAT (Continued) block of wood, because those substances are better con- ductors of heat and more quickly take heat away from the hand. Charcoal is an instance of a bad conductor, so that a short stick of it can be made red-hot at one end and held by the hand at the other without feeling any pain. Air also is a bad conductor, as are, indeed, all gases. The metals as a class are good conductors. When water is sufficiently heated in a closed vessel that is to say, in such a way that the vapour or steam cannot escape the temperature of the water goes beyond its ordinary boiling-point and any steam that is generated is held under pressure, the boiling-point of the water increasing with the pressure. Of course, this can only be done in very strong vessels, otherwise they would explode with violence. When water is heated in this way to a temperature of 121 C. that is, 21 C. above its ordinary boiling-point the pressure of the steam generated is equal to 30 pounds on the square inch ( = to 2 atmospheres of 30 inch mercury), and the construction of steam-engines is based upon a knowledge of these facts. Steam under pressure as generated in locomotives, is used to force down a piston in a cylinder, and this is made to operate on wheels with which it is connected, in such a way as to bring and maintain a train in motion. This illustration will also serve to explain again what has already been referred to when describing force and energy. The great heat generated by the burning fuel used under the boiler is taken up by the water and converted into energy or force ; that is to say, water which at the ordinary temperature of the air is a quiet, harmless liquid, can, by becoming heated in the form of steam, assume an energy so great that, unless the boilers were made of intensely strong material, it would cause them to explode. Illustrations of the conversion of chemical action into energy are also afforded by the explosion of a mixture of petrol vapour and air as utilized in the engines of motor vehicles, and by the use of gunpowder. (See Gunpowder, also Explosives.) Heat has often been described as a mode of motion, and its mechanical equivalent is expressed by the ascertained fact that a weight of i Ib. falling through 778 feet may produce by friction or otherwise, enough heat to raise the temperature of i Ib. of water i F. It is of importance to note that substances vary very much in their capacity for heat. (See Specific Heats.) For 244 HEAT HEAT (Continued) example, water requires more than twice as much heat to raise it to any particular temperature, as does an equal weight of quicksilver (mercury), and this fact in itself is a confirmation of the view that matter and force are one and inseparable. It is all a matter of state, and we only recognize a substance or any particular form of matter by the expressions or properties given to it by the forces which control it i.e., subject to which it exists in any particular phase or in a particular environment. When a gas, such as carbon dioxide, is liquefied as it can be by cooling and pressure, and then allowed to escape by a jet from its container, some part of the escap- ing gas will absorb heat from the other part, causing it to be deposited in the solid form, resembling snow. In a similar way, snow when lying on the ground, during a thaw, will, by absorbing heat from its surroundings, cause ice to be produced in its immediate vicinity. (See Refrigeration.) In passing from the solid to the liquid state, there is what appears to be a disappearance of heat, so that when solid ice liquefies to water, the heat which thus disappears or is rendered latent would suffice to raise the same weight of water through 79 C. On the other hand, when water is frozen, this so-called heat of liquidity is evolved, and a corresponding evolution of heat takes place when all sub- stances pass from the liquid to the solid form, the amount varying with the particular substances. Thus, when a saturated solution of sodium sulphate is suddenly agitated, it at once crystallizes, and the thermometer will indicate an immediate rise of temperature. Again, heat is rendered latent when substances pass from the liquid to the gaseous state, as when, for example, water is converted into steam, the latent heat of which is 536 thermal units. The British thermal unit is that required to raise i Ib. of water at its temperature of maximum density, i F. = 250 gram-calories ; the gram-calory being the amount of heat required to raise i gram of water through i C. Many chemical actions are brought about by employing the agency of heat, and nearly all kinds of combustion are initially dependent upon its employment. For example, a fire as laid in a domestic grate will not burn unless heat in the form of a lighted match be first of all applied to it. Heat is all-powerful, too, in breaking up many chemical combinations, causing, in other words, the dissociation of their component parts by overpowering the force by which HEAT HELLEBORE 245 HEAT (Continued) they are previously united or held together. Even steam can be thus broken up into its component parts (hydrogen and oxygen gases) by the agency, for example, of a piece of platinum metal intensely heated. HEAVY SPAR Barium sulphate (BaSO 4 ). HEDERIC ACID A derivative prepared from a glucoside (Hederin) contained in ivy leaves and seeds (Hedeva helix). HEHNER VALUE (of fats, oils, and waxes) represents the percentage of insoluble fatty acid + the non-saponifiable constituents. HELIOTROPIN (Piperonal) (CH 2 O 2 : C 6 H 3 .CHO) A white, shining, crystalline substance prepared synthetically from safrol and piperine, and used in medicine and perfumery. Mixed with vanillin it is sold as " white heliotrope." HELIUM (He) Atomic weight, 4 ; melting-point below - 271 C. It was previously known as a constituent of the sun's atmosphere, but much more recently recognized as present in the air in extremely minute quantity (i to 2 volumes in 1,000,000) and in certain mineral spring waters, notably those of Bath. It is also found in association with a large nuniber of mineral compounds of uranium, thorium, and other rare earths, including cleveite and uraninite (pitch- blende). It is a colourless gas of very light character (density 2), ranking next to hydrogen in this respect. It is also said to be a disintegration product of radium emana- tion ; but if that be correct, then, of course, radium cannot be regarded as an element. In common with the other members of the argon group it is very inert and practically devoid of chemical characters. Certain wells of natural gas in many parts of the world contain small proportions of helium and some in Texas contain from i to 2 per cent. This has been produced in large quantities to fill airships, having the advantages over hydrogen of being non-inflam- mable and non-explosive. (See Radium and Lead.) There is also a natural gas-supply at Hamilton, Ontario, from which it has been found practicable to isolate helium of 97 per cent, purity on a commercial scale, at a cost of less than 2^-d. per cubic foot. HELLEBORE as obtained from the root of the black variety (Helleboms niger) contains a nitrogenous, crystalline sub- stance soluble in alcohol, named helleborine. Pharma- ceutical preparations are made from the roots of the white and green hellebores. 246 HEM A TINE- HESPERIDENE HEMATINE A colouring matter prepared in the forms of crystals, paste, and liquor from logwood extract, and not to be confounded with the red colouring matter of blood corpuscles (haematine). HEMLOCK (Conium maculatum) contains an active, narcotic, alka- loidal principle known as coniine (C 8 H 17 N), a colourless, oily body, soluble in water, alcohol, and ether, which can also be produced by artificial processes. (See Logwood Extract.) HEMP8EED OIL is obtained by pressing or extraction from hempseed (Canndbis sativa), and is of faint green colour, non-drying in character, and turns brownish-yellow upon standing. It has a sp. gr. of 0*925 to 0*928, a saponifica- tion value of about 192*5, and an iodine value of 148. It is soluble in ether, benzol, and carbon disulphide, and is used for illuminating purposes and in making soft soaps, paints, and varnishes. HENBANE from Hyoscyamus niger A poisonous plant con- taining two alkaloids named hyoscyamine (a white, crys- talline alkaloid (C 17 H 23 NO 3 )) and hyoscine (an uncrys- tallizable alkaloid (C 17 H 21 NO 4 )). The plant is stated to grow wild on the north coast of Somerset. Hyoscine is a powerful narcotic and hyoscyamine exhibits mydriatic action. Wild Manchurian henbane seeds (ten-sen-si) have been found recently to contain scopolamine instead of hyoscyamine. HENNA (Al-Kenna) The root and leaves of Lawsonia inermis, employed in the East to dye the nails, teeth, hair, and garments. A recent investigation has revealed the presence of a crystalline orange-yellow colouring matter in the leaves, which is soluble in water, and dyes wool and silk. With alkalies it gives a bright orange-red colouration, and has the composition C 10 H 6 O 3 . HEPTANE See Hydrocarbons. HEPTYL See Alcohols. HEPTYLENE (C 7 H 14 ) A hydrocarbon of the olefine series. HERMETICAL SEAL The closure of a hollow vessel by melting or cementing the lips of its orifice or opening. Thermometers are hermetically sealed. HEROIN (Diacetylmorphine) A white, crystalline, poisonous de- rivative of morphine, used in medicine ; melting-point, 1 7 1 C. HERRING OIL See Fish Oils. HESPERIDENE A terpene constituent of oil of orange. (See Essential Oils.) HEX A MINE HONE Y -STONE 247 HEXAMINE (C 6 H 12 N 4 ) A white, crystalline substance, soluble in water and alcohol, prepared by the action of formaldehyde on ammonia, and used as an internal dis- infectant for the urinary system, the acid of the urine converting it into formaldehyde. It was used in masks as an absorbent for phosphene gas in the recent war. HEXANE See Hydrocarbons. HEXOSES A group of carbohydrates, including the sugar-like constituents of ripe fruits (a-glucose, a-fructose, etc.). HEXYLENE (C 6 H 12 ) A hydrocarbon of the olefine series. HIGH-BOILING TAR ACIDS See Phenoloids. HIPPURIC ACID (C 9 H 9 NO 3 ) A constituent of the urine of horses, being an amino-derivative of benzoic acid, which is converted into hippuric acid in passing through the animal body. It is a white, crystalline body, of melting-point about 190 C. ; easily soluble in alcohol and hot water. HOLLANDS A gin-like spirit made in Holland from grain. HOLMIUM (Ho) Atomic weight, 163-5. A recently dis- covered, very rare element of the yttrium group occurring in the minerals thulium, gadolinite, samavskite, etc. Its com- pounds are but little known. HOMATROPINE (C 16 H 21 NO 3 ) A white, crystalline, poisonous base allied to atropine, which melts at 95*5 C. and exercises a mydriatic action or power of dilating the pupil of the eye. HOMATROPINE HYDROBROMIDE (C 16 H 22 NO 3 Br) A white, crystalline salt, soluble in water and alcohol, used to dilate the pupil of the eye ; melting-point, 213-8 C. HOMOGENEOUS Of uniform composition. HOMOLOGUES Substances having a relative or corresponding position in a series of analogous bodies. For example, the paraffins, the olefines, and the alcohols are homologous series rising in degrees of the constituent or radical group CH 2 . Substances belonging to such series exhibit, more or less, gradations of many properties and boiling-points. (See Alcohols and Hydrocarbons.) HONEY contains cane sugar and from 61 to 75 per cent, of a glucose named grape sugar or dextrose. HONEY-STONE (C 12 Al 2 O 12 ,i8H 2 O) A crystallized native mellitate of aluminium occurring in lignite found in Thuringia, Bohemia, and Moravia. 248 HOPHUBNERITE HOP The fruit of this plant (Humulus lupulus] contains a yellow, bitter powder named lupulin, of mixed constitution including a resin, a waxy body, and extractive matters, and when distilled with water it yields valerianic acid and a volatile oil. (See Oil of Hops.) The real bitter principle is said to form about from 8 to 12 per cent, of the lupulin powder of which the hop fruit contains about 10 per cent., and includes an acid named humulon. "HOPOL POWDER" A proprietary preparation to make liquid metal polish by mixing with a turpentine substitute. HOPS (OIL OF) is obtained from hop cones which yield it upon distillation with water, being derived from the lupulin or yellow bitter powder which is contained in them, to the extent of from about 8 to 12 per cent. It is green in colour, has the odour of thyme, and is said to contain geraniol and a terpene. It is soluble in alcohol and ether and has a sp. gr. 0-855 to 0'88o. HORMONES A class of substances secreted by special glands in the living body and regarded as essentials to perfect nutrition to the extent of something less than i per cent. of the food. One of these substances is named thyroxin, and is secreted by the thyroid gland, but its chemical nature and constitution are not at present fully ascertained. Another is secreted by the salivary glands, and a third is choline. which is found in the alimentary and intestinal tracts of animals. These hormones are not proteins, and are usually soluble in alcohol and ether, but they are probably nearly allied to the substances referred to under the heading of Vitamines. HORN-BLENDE A mineral consisting of compound silicates of various metals (magnesium, iron, and calcium) in association, otherwise known as amphibole. HORN-MERCURY (Horn-Quicksilver) A native form of mer- curous chloride (Hg 2 Cl 2 ) (calomel). HORN-SILVER (Cerargyrite) Native silver chloride (AgCl 2 ) found in some of the American States. HORSEMINT OIL (Monarda Oil), distilled from the herb Monarda punctata, is yellowish-red, soluble in alcohol and ether, having a sp. gr. of about 0*92 to 0-94, and used in compounding liniments. HUBNERITE Mineral manganese tungstate (MnWO 4 ) found in certain American States. HUMIDITY HYDROCARBONS 249 HUMIDITY Moisture present in the air. The temperature at which air is saturated with moisture and begins to deposit it is known as the dew-point. (See Air.) HUMUS Decayed vegetable matter as found present and formed from cellulose in soil, containing a substance called humic acid, and it is on record that oxidation of phenols in alkaline solution leads to the formation of substances which have all the properties of natural humic acids, one of them having the formula C 6 H 4 O 3 . 4 * HYCOL " A phenoloid disinfectant emulsifying with water. HYDRA3TINE (C 21 H 21 O 6 N) A white, poisonous alkaloid from the root of Hydrastis canadensis, used in medicine. By oxidation it yields hydrastinine (C^t^OgN), which is also used in medicine; melting-point, 131 C. HYDRATES See Bases. HYDRIDES A term given to a number of combinations of hydrogen with metals such as arsenic hydride (AsH 3 ) and lithium hydride (LiH) ; also to combinations of hydrogen with alcohol radicals such as ethyl hydride (ethane) (C 2 H 6 or C 2 H 5 H). HYDRIODIC ACID See Iodine. HYDROBROMIC ACID See Bromine. HYDROCARBONS Combinations of carbon and hydrogen, constituting a large body of organic compounds of great interest and importance. The more important ones may be roughly classified as follows : (i) The Paraffins a series of homologous saturated hydro- carbons of which the lower and best-known members are Methane (CK 4 ) with a boiling-point of - 164 C. and sp. gr. 0-415 at boiling-point. Ethane (C 2 H 6 ) with a boiling-point of - 84 C. and sp. gr. 0-446 at o C. Propane (C 3 H 8 ) with a boiling-point of - 37 C. and sp. gr. 0-536 at o C. Butane (C 4 H 10 ) with a boiling-point of + i C. and sp. gr. 0*600 at o C. Pentane (C 5 H 12 ) with a boiling-point of 37 C. and sp. gr. 0-627 at I 4 C. Hexane (C 6 H 14 ) with a boiling-point of 69 C. and sp. gr. 0-658 at 20 C. Heptane (C 7 H 16 ) with a boiling point of 98 C. and sp. gr. 0-683 at 20 c - 250 HYDROCARBONS HYDROCHLORIC ACID HYDROCARBONS (Continued) These hydrocarbons exhibit a step-by-step rise of CH 2 and a gradual rise in the specific gravities. Under suitable conditions they can be oxidized by air to fatty acids. Methane is a constituent of " marsh gas " and " fire- damp," and often results from the decomposition of organic matter under water. Coal gas contains about 40 per cent, methane. It burns with a faintly luminous flame and forms an explosive mixture with air or oxygen. Ethane is a gas contained in crude petroleum and can be prepared by the electrolysis of acetic acid and other- wise. Like methane it burns with a slightly luminous flame. Propane and Butane are also gases, while the next three members of the series are colourless, mobile, inflammable liquids with boiling-points as above set forth, found in paraffin oil as obtained from cannel-coal and in petro- leum oil. Pentane is a colourless, mobile, inflammable, pleasant- smelling liquid soluble in alcohol and ether, and can be obtained by the fractional distillation of petroleum. It is sometimes used as an anaesthetic, and in the artificial manufacture of ice. The liquid paraffins are all soluble in alcohol and ether but not in water. (2) The Olefines or Ethylene series are described under that heading. (3) The Acetylene series of general formula C w H 2w _ 2 con- tain 2 atoms of hydrogen less than the olefines, including acetylene (C 2 H 2 ), which is separately described. (4) The Benzene Hydrocarbons, of which the best-known members are Benzene (C 6 H 6 ), which boils at 80-4 C. and has a sp. gr. of o'874. Toluene (C ? H 8 ), which boils at 110 C. and has a sp. gr. of 0*869. Xylene (C 8 H 10 ), of which there are several modifica- tions. (See also Benzene, Toluene, and Xylene.) (5) A group having a benzene nucleus including naph- thalene (C 10 H 8 ) and anthracene (C^H^) ; and (6) The Terpenes (C 10 H 16 ), which are described under that heading. HYDROCHLORIC ACID See Chlorine. HYDROCYANIC ACID HYDROGEN 251 HYDROCYANIC ACID or PRUSSIC ACID (HCN) is a colour- less gas of peculiar odour like that of bitter almonds, and is intensely poisonous. It is prepared by the action of dilute sulphuric acid upon potassium cyanide (from which mixture the acid can be distilled over with the water), or in a pure state by passing hydrogen sulphide over dry mercuric cyanide Hg(CN) 2 + H 2 S = 2 (HCN) + HgS. In liquid form the pure acid is a volatile fluid which boils at 26-5 C. and solidifies at 15 C. Upon keeping, it undergoes change into ammonium formate HCN + aH 2 = NH 4 CH0 2 . It is soluble in water, alcohol, and ether, and by combina- tion with bases, forms cyanides ; a large number of double cyanides are also known. The most important commercial cyanogen compound is potassium cyanide. (See also Amygdalin.) HYDROFLUORIC ACID See Fluorine. HYDROFLUOSILICIC ACID See Silicon. HYDROGEN (H) and its Compounds Atomic weight, i ; melting-point, - 259 C. Hydrogen does not exist to any considerable extent in nature in the free gaseous state, although it is believed to be present in very large amount in the atmosphere of the sun. At ordinary temperatures it is a colourless gas, soluble to some extent in water (i volume of which at o C. dissolves 0*021 volume of the gas), is without taste or smell, and is the lightest known substance, so that the relative weights of all other elements and substances are generally compared with hydrogen as the unit. In its ordinary form hydrogen is a comparatively inactive substance, but it can be prepared in an activated state by the action of alpha rays, or by heating a metallic filament in the gas at low pressure, also in the explosion of oxy- hydrogen mixtures by the silent electric discharge. In this active form it is capable of reducing potassium perman- ganate to the lower manganate, indigo blue to indigo white, and combining with nitrogen to form ammonia. This activated hydrogen is regarded as triatomic, and is some- times described as " hyzone " (H 3 ). It is, however, very unstable, and is stated to revert to the inactive state in less than one minute. Hydrogen gas is inflammable, and when a stream of it is burned in the air or oxygen gas it forms water by combina- tion, thus : 252 HYDROGEN HYDROGEN (Continued) In recent years, hydrogen has been reduced to the liquid state, in which it is as clear and colourless as water. The gas is most easily made in the laboratory, by the action of dilute sulphuric acid upon the metal zinc, thus : Zn + H 2 SO 4 = ZnSO 4 + H 2 that is to say, the metal is attacked and dissolved by the acid, forming zinc sulphate, which passes into solution, the hydrogen escaping in the form of gas. A mixture of hydrogen and oxygen gas (or air) in certain proportions, will explode when a light or electric spark is applied to the mixture, water being thus produced in the same way as when a stream of hydrogen is burned in the air. Hydrogen, prepared by various industrial processes, is now largely used in the oxy-hydrogen flame for welding, also to fill the bags or floating chambers of air- ships, zeppelins, etc., and in a number of industries, in- cluding the hydrogenation of oils for use in soap-making. Oils treated by this process are converted into solid fats by the assimilation or absorption of hydrogen ; for example, oleic acid (C 18 H 34 O 2 ) absorbs 2 atoms hydrogen, and becomes converted into stearic acid (C 18 H 36 O 2 ). The hydrogen for this purpose may be prepared either by passing the vapour of water over iron prepared in a spongy condition, at a high temperature, by which the oxygen is made to combine with the iron and the hydrogen gas is set free ; or by the electrolysis of water, in which process the hydrogen is evolved at one pole of the generator and the oxygen at the other. The " Silicol " process consists in the decomposition of silicon alloys, such as ferro- or mangano-silicons (obtained in the electric furnace), by a strong solution of caustic soda, containing from 35 to 40 per cent, of NaHO, the heat generated by the soda solution being sufficient to start the reaction Si + 2NaOH + H 2 = Na 2 SiO 3 + 2H 2 . Another method of preparing hydrogen is by the action of water on an alloy of magnesium and lead. The Linde- Frank-Car o process operates by liquefying all the constituents of water gas except hydrogen. Another process depends upon the oxidation of the carbon monoxide of water gas, and then separating the carbon dioxide thus formed from the remaining hydrogen by under pressure through water. HYDROGEN HYDROGEN DIOXIDE 253 HYDROGEN (Continued) The hydrogenation of oils is brought about by the influence of so-called catalytic agents, the metal nickel (varying in amount from 0^25 to i per cent, of the weight of the oil) being mostly used for this purpose, although palladium, platinum, cobalt, and other metals, can be used. The catalytic agent is, of course, brought into contact with the oils to be treated and the hydrogen at the same time, and there are many modifications of plant for bringing this about. Many oils such as whale oil, otherwise difficult to purify and having objectionable properties, are thus deodorized and turned into solid fats more easily and economically adapted for soap-making, or made fit for edible use, Fat hardening in Switzerland is chiefly conducted with the oils obtained by cold pressure from sesame seed and ground nuts. After refining, they are mixed with the catalyst (very finely divided nickel oxide or salt) and heated to from 1 00 to 260 C. in a high steam jacketed autoclave, the hydrogen (which is prepared from water by the electro- lytic method purity being essential) being introduced through pipes into the mixture. Hydrogen combines with oxygen to form two oxides viz., water (H 2 O) and hydrogen dioxide (peroxide) (H 2 O 2 ). With the halogens, it forms the four acids known as hydrochloric (HC1), hydrobromic (HBr), hydri- odic (HI), and hydrofluoric (HF). Combinations of it with nitrogen and oxygen are also known in the forms of nitrous acid (HNO 2 ) and nitric acid (HNO 3 ) ; and with sulphur and oxygen in the forms of sulphurous and sulphuric acids (H 2 SO 3 and H 2 SO 4 ). It forms a constituent part of all hydrocarbons that is, combinations of hydrogen with carbon, and with carbon and nitrogen it forms hydrocyanic acid (HCN). With sulphur alone, it forms the compound hydrogen sulphide (H 2 S), and is a constituent of innumerable organic compounds. With nitrogen alone, it exists in combination as am- monia (NH 3 ), and it forms so-called hydrides with many metals, such as arsenic and antimony, the arsenical com- pound being what is otherwise known as arseniuretted hydrogen (AsH 3 ). HYDROGEN CHLORIDE See Chlorine. HYDROGEN DIOXIDE or PEROXIDE OF HYDROGEN (H 2 O 2 ) is a very interesting substance nearly related to water, and differing therefrom, in that its molecule contains i atom 254 HYDROGEN DIOXIDE HYDROGEN DIOXIDE (Continued) more oxygen. It can be prepared in a number of ways, one of which consists in mixing barium peroxide (BaO 2 ) with dilute sulphuric acid, when the following interaction takes place : H 2 O 2 . Another method consists in treating barium peroxide in the presence of water with carbon dioxide under pressure. The dilute solution of hydrogen dioxide thus resulting, can be concentrated to some extent by evaporation, or it can be purified by distilling at a low pressure and concentrated up to 90 per cent, by an appliance known as the " sulphuric acid concentrator," and from this solution 100 per cent. peroxide can be obtained by fractional freezing. The pure peroxide is quite stable if kept at o C. ; its freezing point is 1-7 C., and its sp. gr. at o C. is i'4633. As ordinarily prepared, it is often unstable and apt to de- compose with explosive violence. There is also a process for making this compound by electrolyzing sulphuric acid (using a platinum anode), and the subsequent conversion of the persulphuric acid thus produced into hydrogen dioxide. It is stated that sodium persulphate can be produced to a greater degree of concen- tration than the free acid, and that distillation of the once recrystallized sodium salt gives reasonably high yields of the peroxide. It is always found amongst the products which result when phosphorus or turpentine, and terpenes generally, are exposed to air and moisture. It also occurs in nature, being found present in the air following lightning discharges and under some other circumstances. Hydrogen dioxide readily parts with its second atom of oxygen and is a very valuable sanitary and oxidizing agent, being one of the constituents of the disinfecting fluid known commercially as "Sanitas" Fluid. Solutions of it in water are largely used for bleaching straw, hair, and other articles, also in the practice of surgery, on account of its antiseptic character and its power to destroy septic matter in wounds by oxidation. It is odourless and colourless like water, to which substance it is reduced when it parts with its active oxygen : It, is soluble in alcohol, and a dilute solution of it in water can be used to restore oil-paintings which have HYDROGEN DIOXIDE HYDROMETER 255 HYDROGEN DIOXIDE (Continued) become discoloured owing to the formation of lead sulphide (through exposure to the air of towns containing sulphur), by reason of its power of oxidizing the black sulphide into white lead sulphate. HYDROGEN SULPHIDE See Sulphur. HYDROGENATION (OF OILS) See Hydrogen. HYDROLYSIS The splitting up of a more or less complicted substance into simpler or proximate bodies by the fixation of water ; enzymes, acids, and alkaline hydrates being the agents often employed for this purpose. The decomposition of fats by the agency of superheated steam is also an act of hydrolysis. (See Soap, Amygdalin, and Glucosides.) HYDROMETER An appliance of a simple character for determining the approximate specific gravity of liquids. It consists of a graduated glass tube, A, swelling to a globe of glass, B, counterpoised by an adjusted weight which often takes the form of a small quantity of mercury imprisoned in the smaller bulb, C. When placed in any liquid contained in a cylinder sufficiently deep (as shown in figure), it sinks until it has displaced a volume of the liquid equal to its own weight. In a heavy liquid it will sink to a smaller extent than in a lighter liquid. They are made of several types i.e., for liquids lighter than water and for those which are heavier ; but in both cases they are constructed so that a part of the graduated stem floats above the surface of the liquid, the density of which is to be determined. Sikes's hydrometer for ascertaining the alcoholic strength of spirituous liquors is constructed on this principle, and there are tables made out so that the graduations on the stem correspond to definite percentages of alcohol, water being marked as zero or the standard. "Proof spirit" consists of 5072 parts water and 40/28 parts alcohol by weight, and indicates alcohol of sp. gr. 0-920 at 60 F. (15-56 C.). It is important in determining densities by means of the hydrometer to pay great attention to the temperature, as small differences in that respect make considerable varia- tions in the result. It is usual to observe at a tempera- ture of 60 F. or 15-56 C., at which temperature the hydro- meter is graduated. HYDROMETER HYDROMETER (Continued) SPECIFIC GRAVITIES (DENSITIES) ON BAUME'S HYDROMETER FOR LIQUIDS LIGHTER THAN WATER AT 60 F. OR 15*56 C. Degrees. Sp. Gr. Degrees. Sp. Gr. Degrees. Sp. Gr. Degrees. Sp. Gr. 10 I '0000 26 0-8974 4 1 0-8187 56 0-7527 II 0-9929 27 0-8917 42 0-8140 57 0-7487 12 0-9859 28 0-8861 43 0-8092 58 0-7447 I 3 0-9790 2 9 0-8805 44 0-8046 59 07407 J 4 0-9722 30 0-8750 45 0-8000 60 0-7368 15 0-9655 31 0-8696 46 07955 61 0-7330 16 0-9589 3 2 0-8642 47 0-7910 62 0-7292 I 7 0-9524 33 0-8589 48 0-7865 6 3 0-7254 18 0< 9459 34 0-8537 49 0-7821 64 0-7216 19 0-9396 35 0-8485 5 0-7778 6 5 07179 20 G'9333 36 0-8434 5i 07735 66 0-7143 21 0-9272 37 0-8383 52 0*7692 67 07107 22 0-9211 38 0-8333 53 0*7650 68 0-7071 23 0-9150 39 0-8284 54 0*7609 69 07035 2 4 0-9091 40 0-8235 55 0-7568 70 0-7000 25 0-9032 The degrees of TwaddelFs hydrometer are convertible into corresponding specific gravities by multiplying them by 0-005 an d adding rooo. DEGREES ON TWADDELL'S HYDROMETER, AND THE CORRESPONDING DENSITIES AT 60 F. OR 15-56 C. Degrees. Sp. Gr. Degrees. Sp. Gr. Degrees. Sp. Gr. Degrees. Sp. Gr. I 1-005 II 055 21 I-I05 31 155 2 oio 12 060 22 I-IIO 32 160 3 015 13 065 23 I-II5 33 165 4 O2O *4 070 24 I-I2O 34 170 5 025 15 075 25 I*I25 35 **75 6 030 16 080 26 I-I30 36 180 7 035 i7 085 27 I-I35 37 185 8 040 18 090 28 I-I40 38 190 9 045 19 095 29 IBI 4S 39 i'i95 10 050 20 i-ioo 30 1-150 40 i -200 HYDROMETER" HYDROSOL " 257 HYDROMETER (Continued) SPECIFIC GRAVITIES (DENSITIES) CORRESPONDING TO DEGREES OF BAUME'S HYDROMETER FOR LIQUIDS HEAVIER THAN WATER AT 60 F. OR 15*56 C. Degrees Sp. Gr. Degrees. Sp. Gr. Degrees. Sp. Gr. Degrees Sp. Gr. I -OOOO 18 1-1417 3 6 1-3303 54 1-5934 I 1*0069 19 1-1508 37 1-3426 55 1-6111 2 1-0140 20 1600 38 I-355I 56 1-6292 3 I -O2 1 1 21 1694 39 1-3679 57 1-6477 4 1-0284 22 1789 40 1-3810 58 1-6667 5 I<0 357 23 1885 4i 1-3942 59 1-6860 6 1-0432 24 1983 42 1-4078 60 1-7059 7 1-0507 25 2083 43 1-4216 61 1-7262 8 1-0584 26 2185 44 I-4356 62 1-7470 9 1-0662 27 2288 45 1-4500 63 1-7683 10 1-0741 28 1-2393 46 I -4646 64 1-7901 ii 1-0821 29 1-2500 47 1-4796 65 1-8125 12 1-0902 30 1-2609 48 1-4948 66 I-8354 I 3 1-0985 3 1 1-2719 49 1-5104 67 1-8590 J 4 1-1069 32 1-2832 50 1-5263 68 1-8831 15 I ' II 54 33 1-2946 5i 1-5426 69 1-9079 16 1-1240 34 1-3063 52 I'559I 70 1*9333 17 1-1328 35 1-3182 53 1-5761 HYDRO-EXTRACTORS See Centrifuges. HYDROQUINONE or QUINOL (Dihydroxybenzene) (C 6 H 4 (OH) 2 ) A white, crystalline compound used as a developer in photography on account of its strong reducing action. It melts at 169 C. and can be obtained by the hydrolysis of the glucoside named arbutin, or by the oxidation of quinic acid (C 7 H 12 O 6 ) with lead dioxide, etc. It is soluble in water, alcohol, and ether. " HYDROS "An abbreviated name for hydrosulphite of sodium, used as a decolourizing agent, by removal of iron compounds from soap after the process of saponifi- cation is completed (2 to 3 Ib. being used for every 1,000 Ib. of fats). "EYDROSOIi" See Colloid, 258 HYDROSULPHIDESHYPOCHLORITES HYDROSULPHIDES (Sulphydrates) If potassium be heated in hydrogen sulphide gas potassium hydrosulphide is formed, hydrogen being at the same time set free and the same substance is produced in solution, by passing a current of hydrogen sulphide into a solution of potassium sulphide = 2KHS. Hydrosulphides of the alkalies and alkaline earths are also termed sulphydrates. Sodium hydrosulphide (NaHS.2H 2 O) can be obtained in the form of colourless needles, soluble in water, by treating calcium sulphide with sodium bisulphate. HYDROXIDES See Bases. HYDROXYL (HO) A monad radical group which exists in many chemical combinations, such as hydroxylamine that is, ammonia (NH 3 ) in which one of the hydrogen atoms is replaced by the group HO, becoming NH 2 (OH). (See Oximes.) Again, ethyl alcohol (C 2 H 6 O) may be regarded as con- stituted of the radicals C 2 H 5 and HO (C 2 H 6 HO). HYGROMETERS Special varieties are made for determining the humidity of the air in timber, leather, and paper-drying rooms, etc. (See Air, p. 9.) HYGROSCOPIC The property of absorbing moisture from the air. This is not limited to solids ; sea water, for example, is capable of absorbing moisture from the air when saturated with it, at the same temperature. HYOSCIME See Henbane. HYOSCYAMINE See Henbane. HYPO as a prefix in chemical nomenclature is used to dis- tinguish a compound from other members of a series, as, for example, nitrous and nitric acid the term hyponitrous acid indicating the acid containing the least oxygen. HNO 2 is nitrous acid, HNO 3 is nitric acid, and H 2 N 2 O 2 is hyponitrous acid. "HYPO" This term is also used as a common name for sodium thiosulphite (hyposulphite) of sodium. HYPOCHLORITES Salts of hypochlorous acid. (See Chlorine,) HYPOCHLOROUS ACID IMPERMEABLE 259 HYPOCHLOROUS ACID See Chlorine. HYPOPHOSPHOROUS ACID See Phosphorus. HYPOSULPHITE OF SODIUM See Sodium. HYPOSULPHUROUS ACID See Sulphur. HYPOTHESIS A conjectural or speculative view of matters not in opposition to ascertained facts. HYSSOP OIL A colourless essential oil distilled from the herb Hyssopus officinalis. It is soluble in alcohol and ether, has a sp. gr. of 0*932, and is used in medicine, etc. ICE See Water ; also footnote in Heat section (p. 240). ICELAND MOSS A lichen (Cetraria islandica) containing a mucilage which can be extracted by hot water. ICELAND SPAR (Calcite Transparent Calcspar) A mineral form of calcium carbonate. ICHTHYOCOLL See Isinglass. ICHTHYOL An indefinite chemical mixture of sulphonated hydrocarbons obtained by the dry distillation of certain bituminous shales ; used in medicine. IGNITION Setting on fire or taking light. A piece of paper ignites on applying a lighted match. A jet of coal gas takes light in the same way, and both the paper and gas are thus ignited and burn with production of light and heat. The temperature at which combustion of a substance takes place is known as its ignition-point. It is not always necessary to apply a light to cause combustion ; phosphorus takes fire on exposure to the air, and if sodium be warmed in the air it also will burn, forming the peroxide ILANG-ILANG OIL See Ylang-ylang. ILMENITE A mineral compound of iron and titanium oxides. IMIDES Anhydrides of certain acids in which the oxygen atom is replaced by the imido-group (NH) for example, succinimide (C,H 4 (CO) 2 NH), a crystalline substance formed by heating ammonium hydrogen succinate. IMPERMEAELE Fabrics rendered waterproof by various processes are described as impermeable. Bathstone sur- faces can be rendered more or less impermeable by washing over with sodium silicate, and varnishes give impermeability to the surfaces of various articles. 260 IMPER VIO US INDIGO IMPEEVIOUS Not admitting passage. INCANDESCENT A state of heat at which a substance begins to give out light or to glow. The wires of electric lamps and the mantles used for intensifying gas flames are incandescent when in use. INCINERATION The process of reduction to ashes by burn- ing or ignition. INDIAN INK (Chinese Ink) See Inks. "INDIAN OIL" A proprietary quick-drying white spirit distilled from crude mineral oil, of sp. gr. 800, and with closed flash-point over 80 F., advocated as a solvent and turpentine substitute. INDIAN RED A natural pigment from the Persian Gulf, containing ferric silicate (Fe 2 O 3 SiO 2 ). INDIA-RUBBER (Caoutchouc) See Rubber. INDICAN (C 26 H 31 NO 1? ) The active principle of the indigo plant, from which indigo blue is obtained. It is of the character of a glucoside, and is resolved by hydro- lysis into indigo blue and a glucose-like body named indiglucin : 2C 2e H N0 17 + 4 H 2 = C 18 H 10 N 2 2 + 6C 8 H IO O 6 . (Indican.) (Indigo blue (Indiglucin.) or Indigotin.) In the pure state, indican is a colourless substance, but by treatment with acids or by the action of enzymes it is split up as shown by the above equation and yields indigo blue (indigotin), which can be obtained as a dark blue, crystalline powder which sublimes at 300 C. and is soluble in aniline, chloroform, glacial acetic acid, and strong sul- phuric acid. INDICATORS See Volumetric Analysis. INDIGO A blue colouring matter prepared from the plant Indigofera tinctovia and formed from indican, which exists in its juice and that of some other plants, including the West African plant Louchocarpus cyanescens. (See Woad.) Well-made samples are said to contain 70 per cent, of the specific compound indigotin (C 16 H 1 .N 2 O 2 ) associated with other substances which have an influence in the dye-vat, and which probably accounts for the superiority of natural indigo over manufactured indigotin, which is now made synthetically from naphthalene or phthalic acid. INDIGO 261 INDIGO (Continued) The synthetic production of indigo starts with naphtha- lene, which is first of all oxidized to phthalic acid, and this by sublimation is converted into phthalic anhydride (C 6 H 4 (CO) 2 O) which when heated in presence of ammonia yields phthalimide (C 6 H 4 (CO) 2 NH) and this compound when subjected to the action of alkalies and an alkaline hypochlorite produces anthranilic acid (CgHj.NHg.COgH). By interaction with monochloracetic acid, anthranilic acid gives phenyl-glycine-ortho-carboxylic acid, and this when melted with an alkali and made into solution is oxidized by a current of air, thereby producing indigo blue. Another process consists in treating aniline with chloracetic acid, thus producing the phenyl-glycine (C 6 H 5 .NH.CH 2 .COOH), which when heated with soda- mide (NH 2 Na), or metallic sodium in the presence of ammonia, yields indigo blue through oxidation of the inter- mediate compound named indoxyl (C 6 H 4 NH.CO.CH 2 ). The Indian cultivation of indigo has fallen off very much in recent years on account of its synthetic production. Even so late as 1918-19 the acreage under production, which had exceeded one and a half million acres in 1896-7, was less by 59 per cent, than in the previous year, 280,000 acres only being under growth, and yielding about 32,100 cwt. ; although it has been stated that the acreage under culti- vation in 1916-17 had risen to 750,000 acres and produced nearly 5,000 tons of indigo. The indigo plant is cultivated in Southern Nigeria and yields indigo containing 56 per cent, indigotin when treated as in India. Indigo is insoluble in water, but soluble in aniline, nitro-benzene, and chloroform, and dissolves in hot strong sulphuric acid to a deep blue colour ; it is this solution of indigo-sulphuric acid that is used in dyeing. Indigo Blue is prepared by cutting the plants just before flowering and steeping in water, when a fermentation takes place, yielding a yellow-coloured liquor which is drawn off after some twelve to fifteen hours and subsequently agitated in contact with the air, in which process oxygen is absorbed and the indigo is thrown down as a greenish-blue precipitate. This is strained off, pressed, dried, and cut up into the cakes of commerce. The same colouring matter is also yielded by woad (Isatis tinctovia). A considerable amount of indigo is now produced in Manchuria. (See Indican and Indigo White.) 262 INDIGO INKS INDIGO (Continued) Indigo White (Ci 6 H 12 N 2 O 2 ) is a white, crystalline powder obtained from indigo by a process of reduction, and it is used in dyeing, by making use of processes which are capable of reconverting it into indigo blue on contact with the fabrics. Indigo Carmine, or soluble indigo, prepared by treating a sulphuric acid solution of indigo with soda. It is a blue powder soluble in water and used in dyeing. INDIUM (In) Atomic weight, 114*8; sp. gr., about 7-1 ; melt- ing-point, 176 C. A rare element so named on account of the two lines it exhibits in the indigo-blue part of the spectrum. It is supposed to be analogous to aluminium and occurs in many zinc-blendes. It is a ductile, soft, silver-white metal, and its compounds give a violet tinge to the Bunsen flame. It is easily soluble in acids, and forms alloys with lead and thallium. There are two oxides (InO and In 2 O 3 ); a hydroxide (In(OH) 3 ) ; two chlorides (InCland InCl 2 ) ; a bromide (InBr 3 ); iodide (InI 3 ) ; nitrate (In(NO 3 ) 6 ,9H 2 O) ; sulphate (In(SO 4 ) 3 ), etc. The metal resembles aluminium in forming alums and the halogen salts are soluble in water. INDUCTION The power exhibited by a body of inducing a corresponding state in another body, as when a rotating magnet acts in the dynamo. (See Electricity.) INFUSION An extract prepared by steeping or digesting a substance or parts of plants in a solvent liquid. INFUSORIAL EARTH A light-coloured siliceous deposit found near Ebsdorf, also in the United States and else- where, is known by this name, but it is also applied to other deposits such as kieselgiihr and atomite. INHALATION The act of inhaling or breathing in through the mouth and nose. INKS Liquids or pigments used for writing or printing, those for writing being made of various colours black, blue, green, and red. Black Ink is a mixture of an infusion of gall nuts with ferrous sulphate, and a certain proportion of gum arabic dissolved in the mixture to give body and gloss to the ink. Sometimes logwood and indigo carmine are added, and there are many recipes for its preparation. Blue Ink can be prepared by dissolving Prussian blue in a dilute solution of oxalic acid. INKSINORGA NIC 263 INKS (Continue^ Red Inks are prepared from cochineal or Brazil-wood, or by dissolving carmine in ammonia solution. Indelible Ink is prepared, amongst other methods, by mixing ordinary ink with Indian ink or lamp-black rubbed up with weak hydrochloric acid. Copying Ink is prepared from logwood extract dissolved in vinegar and water, to which certain quantities of copper sulphate, alum, gum, and sugar are added. The formula adopted by the United States Government is as follows : Tannic acid ... ... ... 46*8 grammes Gallic acid ... ... ., 15-4 Ferrous sulphate ... ... ... 60*0 ,, Gum arabic ... ... ... 10*0 Dilute hydrochloric acid (U.S. P.) ... 50-0 Phenol ... ... ... ... i'o Suitable blue dye ... ... ... 4-4 and water to make up to 1,000 c.c. at 15*6 C. Cancelling Inks must contain pigment and dyes of such character as to penetrate the fibre of paper so that the mark cannot be removed. They vary in composition, but lamp-black is often used in conjunction with a coal-tar dye and some non-drying oil. Sympathetic Inks are variously prepared, cobalt salts being used for some makes. (See Cobalt.) Marking Ink usually consists of silver nitrate solution coloured and thickened with gum, but many others consist of cresol and dye. Printing Inks are made in great variety, but consist in the main of lamp-black mixed with linseed oil ; soap and rosin being sometimes incorporated. Chinese Ink is made from vegetable charcoal prepared from rice straw or vegetable oils, and suitable materials. Indian Ink is a black powder imported from China, said to be made from carbon prepared by burning camphor, cemented with gelatine or glue. Invisible Ink See Cobalt, p. 126. INORGANIC This term is applied to all substances that do not contain carbon as a constituent, also to some few others in which carbon is present in an unimportant sense. The natural rocks and earths, the metals and 264 INORGANIC INULIN INORGANIC (Continued) minerals, are all inorganic bodies. Such substances as the metallic carbonates are regarded as inorganic for the reason above given. (See Carbon.) INOSITE (Inositol) (C 6 H 12 O 6 )2H 2 O A crystalline sugar-like substance found in the muscles of the heart and in certain other animal tissues. It loses its water of crystallization at 1 00 C., and is not susceptible to alcoholic fermentation. INSECT POWDER (Pyrethrnm Powder) The dried unexpanded heads of Chrysanthemum cineraria folium, of which the ground Montenegrin or Dalmatian variety is the best, its insecticidal properties being due to its constituent pyrethrotoxic acid. INSOLUBLE Incapable of being dissolved. Sand, for instance, is insoluble in alcohol, and all the metals are insoluble in water. INSULATION Detachment or placing out of communica- tion. Electric cables are insulated with a covering of gutta-percha to prevent the leakage of the electric current by conductivity. INTERACTIONS See Chemical Interactions. INTERMEDIATES A general term for a great number of complex derivatives obtained by chemical processes from anthracene, benzene, cresols, naphthalene, phenol, toluene, and other direct coal-tar products, all of which are used in the manufacture of synthetic dyes. They include aniline oil, naphthol (alpha and beta), naphthalene, naphthylamines, phthalic anhydride, anthran- ilic acid, dimethylaniline, nitro-benzene, paranitraniline, resorcin, salicylic acid, and many other compounds, some of which are described under their respective names. INULIN or ALANT STARCH (C 9 H 10 O 6 )>< A carbohydrate contained in dahlia bulbs (Dahlia variabilis) to the extent of about 10 per cent, of the weight of the ripe tubers, and in smaller proportions in the roots of other members of the Composite, such as chicory and artichokes. In the pure state it is a white powder resembling starch, but, unlike that substance, it dissolves in aqueous sodium hydroxide and in hot water to a clear solution, and is not coloured blue by iodine. It is unaffected by diastase, and is not fermentable by yeast, but when boiled with water or dilute acid it is converted into a variety of fructose. It is used in the pre- paration of diabetic bread, and is a stronger sweetener than cane sugar. IN VERT A SE IODINE 265 INVERTASE (Invertin) An enzyme present in ordinary yeast which, apart from the yeast cells themselves, has the power of converting (inverting) cane sugar into glucose and fruc- tose by hydrolysis, to the reported extent of 200,000 times its own weight of cane sugar without then losing its effect C 12 H 22 O n + H 2 = C 6 H 12 6 + C 6 H 12 6 . The product is known as " invert sugar," and whereas a solution of cane sugar is dextro-rotatory, the hydrolyzed product is lasvo-rotatory, the fructose being more strongly laevo-rotatory than the glucose is dextro-rotatory. INVERT SUGAR See Invertase. IODATES See Iodine. IODEOSIN See Volumetric Analysis. IODIC ACID See Iodine. IODIDES See Iodine. IODINE (I) Atomic weight, 127; sp. gr., 4-95; melting- point, 113*5 C. Iodine is widely distributed in nature, being found in compound form (only) associated with potassium, sodium, magnesium, and calcium. It is also present in sea water, seaweeds, and caliche or Chili saltpetre (sodium nitrate). It is prepared to some extent from kelp (ashes from seaweed), but chiefly from the mother-liquor of the Chili saltpetre above named, which contains less than J per cent., and that of the Stassfurt salt deposits. The seaweeds which contain most iodine are of the so- called " drift" order viz., Laminaria digitata and Laminaria stenophylla, each of which contains a little less than \ per cent. The ash of the roots of L. hyperborea contains about i per cent., the stalks about 3 per cent., and that of the leaves about 4 per cent, iodine. Iodine is a blue-black, shining substance, easily obtained in crystalline form, which readily vapourizes, the vapour having a beautiful violet colour. It has a characteristic penetrating odour and is only slightly soluble in water, but readily soluble in a solution of potassium iodide, alcohol, carbon disulphide, chloroform, ether, etc. Even an extremely dilute solution of iodine gives with starch solution an intensely blue-coloured compound. In general properties it strongly resembles its family neighbours chlorine and bromine. Dilute solutions of it in water and alcohol are used in surgery as antiseptics. 266 IODINE IODINE VALUE IODINE (Continued) Iodine in combination with the alkaline metals forms iodides, the most valuable of which is potassium iodide (KI), which is produced in solution together with potas- sium iodate, when iodine is dissolved in a warm solution of potassium hydrate. It crystallizes in anhydrous cubes, is very soluble in water, and is extensively employed as a medicament. Hydriodic Acid (HI) can be prepared in a variety of ways, but most readily by the action of phosphorus upon iodine in presence of water, thus giving rise to production of the HI gas, which is colourless, pungent, and extremely soluble in water, a saturated solution having a sp. gr. of 1*67 at the ordinary temperature and pressure. lodic Acid (HIO 3 ) is a crystalline, white, solid body, soluble in water, and forms iodates such as potassium iodate (KIO 3 ) corresponding to potassium chlorate (KC1O 3 ). Iodine Pentoxide (I 2 O 5 ) is a white, crystalline body, soluble in water, which, when heated to 300 C., is split up into iodine and oxygen. Iodine forms two compounds with chlorine viz., iodine monochloride (IC1) and trichloride (IC1 3 ). Both these compounds are formed by passing dry chlorine gas over iodine, when it first of all melts to a dark reddish-brown colour and subsequently solidifies to a mass of red crystals of IC1 if care be taken not to use an excess of chlorine, but if more chlorine be used, then the yellow trichloride in crystalline form is produced. Iodine Cyanide (ICN) is a colourless, crystalline sub- stance of pungent odour, and soluble in water, alcohol, and ether ; used as a preservative by taxidermists. Periodic Acid (HIO 4 ,2H 2 O) is a white, crystalline body, soluble in water, and having a melting-point of about 131 C. The periodates constitute a large class of salts. IODINE VALUE (of Oils and Fats). This determination, as commonly performed on samples of oils, fats, and waxes, is used to indicate the degree of unsaturation of the compound that is, the number of pairs of carbon atoms in which two (or, in some cases, three) valency bonds are concentrated between the two carbon atoms. Any such double (or treble) linkage is in a state of strain, and when the substance containing it comes in contact with certain other substances (e.g. the halogens), one of the bonds breaks and two atoms of the new substance IODINE VALUE ION ONE 267 IODINE VALUE (Continued) are attached, one to each of the carbon atoms originally joined by the double linkage. Thus every two atoms of the reagent absorbed represent one double linkage in the original substance. The reagent used in the Hubl or Wij method is iodine monochloride (IC1), which adds on one atom of iodine to the one carbon atom, and one atom of chlorine to the other. Thus in this case, one atom of iodine absorbed indicates the presence of one double linkage. The method of Hubl is to make up an iodine mono- chloride solution from iodine and mercuric chloride, and add excess of this to a known weight of the substance. After standing for some time, the excess of iodine chloride is estimated by the potassium iodide and thiosulphate method : a blank test is carried out alongside, using an equal quantity of the reagent without the substance, and the difference indicates the amount of iodine absorbed by the substance. The iodine value may be defined as the amount of iodine chloride absorbed by 100 grms. of the substance, expressed in terms of iodine. The drying properties of oils are in almost direct ratio of their iodine values. Saturated substances such as the paraffins have iodine value nil. IODITE A Spanish native silver iodide containing over 46 per cent, of silver. IODOFORM (CHI 3 ) A yellow, crystalline substance prepared by warming alcohol with iodine and alkali, or by heating acetone with iodine in presence of an alkali. It melts at 120 C., has a peculiar odour something like that of saffron, and is used as an antiseptic in the practice of surgery. Its unpleasant odour is removed by dissolving it in air- oxidized turpentine, without detracting from its value. It is insoluble in water but dissolves in both alcohol and ether. IONISATION Electrolytic dissociation. (See Electricity.) IONIUM A substance possibly of an elemental character obtained as a disintegration product from uranium minerals, giving a spectrum and exhibiting chemical properties identical with those of thorium. IONONE (C 13 H 20 O) An artificial essence of violet made from citral and acetone. There are several so-called ionones, one of which is the odoriferous principle of the iris root. (See Orris Oil.) 268 IONS IRON IONS The moving particles in an electrolytic solution, one set in the direction of the anode and the other towards the cathode; those appearing at the former are sty led anions and the positively charged ions are termed cations. (See Electricity.) IPECACUANHA A substance used as an emetic, prepared from the dried root of certain plants growing in South America and containing several active principles, including " emetine." The best plant is the Psychotria ipecacuanha of Brazil and New Granada, and the greater portion of the emetine is contained in the cortical part. IKIDIUM (Ir) Atomic weight, 193*1 ; sp. gr., 22-4; melting- point, 2,350 C. A white, hard, brittle, and lustrous metal, occurring in alloy form with platinum in platinum ores, and nearly related to that metal in its chemical characters. The native alloy is known as iridosmine. It is used in alloy with platinum for hardening, also in making fountain- pen points. In compact form, iridium is insoluble in acids, and it forms alloys with copper, gold, lead, and mercury. A number of compounds are known, including three oxides (one of which, known as " iridium black," is used as a pigment for china ware), three chlorides (IrCl 2 , Ir 2 Cl 6 , IrCl 4 ), and iodides. Its salts are soluble in water, and, in common with palladium, the metal has the property of absorbing gases by occlusion. (See Occlusion.) IRISH MOSS Seaweed (Chondvus crispus and C. mamillosus) containing nearly 80 per cent, of a peculiar, gelatinous substance named " caregeenin." It finds some use as a food ; it is also used by dyers and calico printers for dress- ing the warp of webs, as an agent for clarifying beer, for certain sizing purposes, and for leather-dressing. IRON (Ferrum, Fe) and its Compounds Atomic weight, 56 ; sp. gr., 7*84 ; melting-point, 1,530 C. Iron occurs in nature in the form of many ores. Magnetic iron ore (magnetite or loadstone) (FeO, Fe 2 O 3 ) is a compound of oxides of iron from which much of the best Swedish iron is made. Red hamatite (Fe 2 O 3 ) is largely mined in some parts of Lanca- shire, Cumberland, and to some extent in Cornwall, while large deposits exist near Bilbao in Spain and elsewhere. It is greatly used in the manufacture of Bessemer pig iron. Brown haematite (2Fe 2 O 3 3H 2 O), a hydrated oxide of iron, is the source of much of the iron made in France and Belgium, whilst enormous quantities of spathic ore or clay ironstone (which is an impure carbonate of iron containing about 33 per cent, of iron, and the poorest of the iron IRON 269 IRON (Continued) ores that are worked) are used in this country as a source of iron. Iron occurs naturally as carbonate in the forms of blackband of the Scotch coalfields, and in an impure form in the neighbourhood of Northampton. Large deposits of micaceous iron ore are found in Brazil, whilst the Lorraine district is said to contain an iron ore reserve of about 1,800,000,000 tons. While in German hands it yielded about three-fourths of their steel output. It is a brown haematite very rich in phosphorus. It has recently been estimated that China possesses, in all, some 7,000,000,000 tons of iron ore available for treat- ment by native methods and modern furnaces. Chromium iron ores come largely from New Caledonia, Rhodesia, the United States of America, and Canada. Iron as manufactured and dealt in commercially is not a pure metal, and varies very much in composition and qualities according to the purposes to which it is to be applied. Some of the better-known kinds are named cast iron, wrought iron, foundry iron, forge iron, steel, etc., and their melting or fusing points and other properties vary with the composition. Some 21,000,000 tons of iron ore were smelted in the United Kingdom in 1916. Electro-deposited Iron is employed in building up worn and other parts of aeroplane engines, and as a material for research work, being the purest available form. It is not, however, chemically pure, as it generally contains some hydrogen gas and small proportions of carbon, sulphur, silicon, and phosphorus. Cast or Pig Iron is made in blast-furnaces from mixtures of iron ore with coal or coke and limestone, by which means (the contents of the furnace being maintained at a bright- red heat by the blast of air) the oxygen contained in the oxides or other iron compounds is burned off by the carbon, the lime combines with the clayey part of the ore and forms the slag, leaving metallic iron. The molten iron settles in a layer at the bottom of the furnace, the slag remaining on its top. " Pig iron " made in this way, containing from 2 to 5 per cent, of carbon and small quantities of sulphur, phos- phorus, and silicon, is used for making stoves, saucepans, iron gates, and many other articles. It is hard and brittle, and more readily fusible (1,530 C.) than wrought iron, which is made from it by remelting and exposure to further 270 IRON AND ITS COMPOUNDS IRON (Continued) oxidation to burn off the carbon and other impurities. The output of pig iron in 1913 was about 10,250,000 tons. Wrought Iron (melting-point, 1,600 C.), when heated to redness, is soft, and can be hammered and joined (welded) into any desired shape, a property which is utilized in smithcraft. The purest form of commercial iron is the fine malleable quality of which wire is made. Steel melts at about 1,350 to 1,375 C. and is pro- duced from wrought iron, which is practically devoid of carbon, by the incorporation of carbon to the extent of from 07 to 17 per cent., and from cast iron by removing the excess of that impurity. It is, in practice, mostly produced by either blowing or otherwise exposing molten pig iron to a blast of air which burns out the carbon, together with other impurities, including silicon, manganese, and sulphur. During the recent war, the electro-thermal steel furnace, which up till then had produced only a small proportion of the metal in this country, came more into use, and by the end of 1918 about 140 furnaces of various types were in use here, with a production of 150,000 tons per annum, the output being principally used in respect of bullet-proof plates, aeroplanes, motor-cars, armour-piercing shells, and steel helmets. It is stated that on the Tyne, electro-thermal steel is now being manufactured at a price which can compete with the acid open-hearth steel, owing to the cheap power of coke- oven gas. The output of steel in this country in 1918 amounted to 9,500,000 tons. So-called mild steel contains from o-i up to about 0-4 per cent, of carbon ; the harder varieties contain up to about 2 per cent., while the largest amount of carbon that iron can be made to take up is just over 4 per cent., correspond- ing to the formula Fe 5 C. In the so-called basic Bessemer process the lining of the converter or oxidizer is made of bricks of magnesian lime- stone cemented together, instead of the siliceous acid material named ganister, which was used in the old Bessemer process, with the result that the phosphorus is removed in addition to the other associated impurities, and concentrated in the slag. It is the phosphorus content of the cast or pig iron that determines to some extent the particular process to be IRON AND ITS COMPOUNDS 271 IRON (Continued) adopted for making steel therefrom. In the absence of phosphorus to any considerable extent, the old Bessemer process suffices, in which the " ganister " lining of the con- verters is employed, air being blown through the molten mass, thus getting rid of the carbon, but leaving some phosphorus and sulphur in the molten metal, which is made more or less brittle in consequence. The basic lining removes these impurities as already explained. In the Siemens-Martin process of steel-making, the cast iron is mixed with specially picked iron ore in furnaces with open hearths heated by producer gas. In the manufacture of steel for industrial employment many other metals are deliberately introduced, manganese, for instance, being used for hardening purposes up to about i per cent, in the so-called Bessemer and open-hearth steels, although for some purposes larger quantities are used ; while nickel is used to produce a toughening effect, and chromium, tungsten, molybdenum, tantalum, and vanadium are severally employed to give particular pro- perties or qualities to steels destined for special applications. Steel containing 13 per cent, chromium and a low per- centage of carbon stainless steel has been rendered possible only by the electric furnace, which is necessary for the preparation of the ferro-chrome s as also for the steel melting. The hardening is brought about by the rapid cooling of steel which has been heated to a high temperature, whilst the tempering of steel is effected by reheating the hardened metal to a temperature much lower than that used for hardening it, and cooling slowly. Ferro- Alloys Iron alloyed with from 12 to 16 per cent, of silicon is very resistant to the action of acids, and the use of this alloy has largely replaced that of glass and stone ware in chemical industry. It is somewhat brittle, and vessels made of it will not withstand great internal pressure, but up to 50 Ib. per square inch they are con- sidered safe. Ferro-Carbon-Titanium is an alloy containing carbon which is sometimes used to make steel tougher. Ferro-Cerium is an alloy containing various metals of the cerium group, and is used in preparing cigar lighters. Ferro-Chrome contains from 50 to 60 per cent, of chromium and 5 to 9 per cent, of carbon. 272 IRON AND ITS COMPOUNDS IRON (Continued} Ferro-Manganese is an alloy of manganese carbide with iron, and contains from 20 to 85 per cent, of manganese. Ferro -Molybdenum, Ferro-Nickel, and Ferro-Phosphorus all have their special applications in steel-making of various qualities, the latter being used when very thin castings have to be made by increasing the fluidity of the metal. Ferro-Silicon An alloy of silicon and iron containing 30 per cent, or more silicon, but no carbon, is used not only in hydrogen-making, but also in conjunction with Ferro-Manganese as a deoxidizing agent for converting white cast iron into grey iron, and in steel manufacturing. Ferro-alloys are used in the steel industry to remove oxygen and nitrogen from the molten steel, or to introduce into the steel a small proportion of the metal in order to adapt it to special applications. To remove oxygen, ferro-manganese, ferro-silicon con- taining 30 per cent, or more silicon, ferro-aluminium, and ferro-titanium are used in very small proportions, the manganese compound being most generally used by reason of its cheapness. From 0*5 to ro per cent, of metal is thus introduced. To remove nitrogen, ferro-vanadium containing from 25 to 40 per cent, vanadium and ferro-titanium are employed ; whilst to introduce the proportion of special metal, ferro- manganese, ferro-vanadium, ferro-chromium, ferro-tungsten, ferro-molybdenum, ferro-titanium, ferro-uranium, ferro- boron, and ferro- zirconium are all used. A steel containing 12 to 14 per cent, manganese is very tough and hard and specially adapted for mining and grinding machinery and making burglar-proof vaults ; one containing from 2 to 4 per cent, chromium is a very hard tool-making material; that containing 15 to 25 per cent, tungsten is a high-speed steel which will cut iron while red-hot ; that containing 6 to 10 per cent, molybdenum is similar to the tungsten variety and is used for lining large guns to increase their resistance to erosion. Steel containing from 0-5 to ro per cent, vanadium is very strong, resists shock well, and is used for making motor-car axles, cranks, piston-rods, etc. The titanium combination containing from i to 2 per cent, of that metal is largely used for making steel rails and sheet-steel. The steel containing about 0-5 per cent, of uranium is said to replace that containing several per cent, of tungsten, IRON AND ITS COMPOUNDS 273 IEON (Continued) and is used for making tools ; while the zirconium variety is well adapted for bullet-proof sheets, armour-plate, and armour-piercing projectiles. Slag (known as Basic Slag) resulting from the manufac- ture of iron and steel, containing phosphorus, finds great employment, when reduced to powder, as a fertilizing agent. (See Slag.) So-called "slag-wool" is made from slag by blowing steam against it when in melted form, being thereby con- verted into fine threads like cotton-wool, and in this form it is used as a covering for steam-pipes and boilers, and as a packing material. Iron Oxides. The three known oxides of iron are ferrous oxide (FeO), ferric oxide (Fe 2 O 3 ), and the so-called mag- netic oxide (Fe.jO 4 , or FeO,Fe 2 O 3 ), the ferrous and ferric salts being derived from the first two named oxides by t combination with acids. Ferrous Oxide (FeO) is a black powder which oxidizes in the air. In combination with water as ferrous hydroxide (Fe(HO) 2 ), it is precipitated when potassium hydroxide solution is added to a solution of a ferrous salt, but it rapidly absorbs oxygen from the air and passes into the ferric oxide (Fe 2 (HO) 6 ). Rust consists of a mixture of the two hydrated oxides and ferrous carbonate, and continued exposure to air effects the oxidation of the ferrous compounds into ferric oxide (Fe 2 3 ). Ferric Oxide, by reason of its hardness, is much used for grinding and polishing, and bloodstone (a hard kind of red haematite) when well polished, is considered the best material for producing a high lustre on coat buttons and on the gilding of porcelain. In the pulverulent form, the ferric oxide obtained by the combustion of ferrous oxalate and other methods is much esteemed for its grinding and polishing characters. Jewellers' rouge for polishing gold and silver is produced by lightly calcining ferrous sulphate, while the article named " crocus" used for polishing brass and steel, is produced by further calcination. Ferric oxide is also used for colouring glass and porcelain. Red ferric oxide paint is an important article of commerce, and considerable quantities are made in the provinces of Jaen and Malaga from haematite ore, which is ground and washed with water, the finest powder being collected and 18 274 IRON AND ITS COMPOUNDS IRON (Continued) dried. After making it into paint, it is used extensively for ships' bottoms and iron work, and as a colouring matter for paper, rubber, tiles, etc. The high grades of Spanish oxides contain from 80 to 95 per cent, of Fe 2 O 3 . Ferric Chloride (FeCl 3 ) can be made by exposing iron to the action of dry chlorine, and in combination with water, in the form of yellow deliquescent crystals (FeCl 3 ,6H 2 O) by dissolving iron in aqua regia, or ferric oxide in hydrochloric acid, and crystallization of the solution. It is soluble in water, is used in medicine, chlorina- tion of silver and copper ores, and as a mordant in dyeing. Ferric Sulphate (Fe 2 (SO 4 ) 3 ) can be prepared by the action of sulphuric or nitric acid, or both, on ferrous sulphate in solution 4 H 2 0+3Fe 2 (S0 4 ) 3 and is obtained by evaporation of the solution as an an- hydrous salt. A combination with water (Fe 2 (SO 4 ) 3 ,9H 2 O ) is also known . Ferric sulphate is used to some extent in medicine, in pigment - making, and for the coagulation of blood in abattoirs, etc. A double sulphate of iron and potassium known as iron alum (K 2 SO 4 ,Fe 2 (SO 4 ) 3 24H 2 O) can be prepared in the form of violet octahedra by dissolving the proper quantity of potassium sulphate in a strong solution of ferric sulphate at o C.and crystallization. Ferric Ammonium Sulphate (Fe(NH 4 )(SO 4 ) 2 i2H 2 O) is a violet efflorescent salt, soluble in water, used in textile dyeing, etc. Ferric Ammonium Citrate A bronze hygroscopic crystalline salt used in photography and medicine. Ferric Acetate (Fe 2 (C 2 H 3 O 2 ) 6 ) A reddish crystalline salt, soluble in water, used in textile dyeing. Ferrous Hydroxide (Fe(HO) 2 ) is produced by adding an alkaline hydrate solution to a ferrous solution, in the form of a whitish precipitate which in contact with air rapidly absorbs oxygen and passes into the dark-coloured ferric oxide. Ferrous Chloride (FeCl 2 ) used as a mordant and in metallurgy can be obtained in pale blue-green crystals in combination with water (Fe,Cl 2 ,4H 2 O) by dissolving iron in hydrochloric acid, and evaporation of the solution. The anhydrous chloride is produced when iron wire is IRON IRONSTONE 275 IRON (Continued) heated in gaseous hydrochloric acid, the chloride volatilizing and subliming in white deliquescent crystals. Ferrous Sulphate or Green Vitriol (FeSO 4 ,7H 2 O) results from dissolving metallic iron in dilute sulphuric acid and is obtained upon evaporation of the resulting solution, in pale green crystals of an efflorescent character, which are soluble in water (70 parts in 100 at 15 C.). Upon heat- ing to 100 C. these crystals lose 6 molecules of water and the residual compound is therefore FeSO 4 ,H 2 O. Ferrous sulphate is used in making inks, pigments, and other articles. Ferrous Acetate (Fe(C 2 H 3 O 2 ) 2 ) is extensively used under the name of " iron liquor " as a mordant in dyeing. Iron combines with sulphur to form several distinct sulphides (FeS, Fe 2 S 3 , and FeS 2 ), the last named being found in nature in large quantities as iron pyrites ; there is also a so-called magnetic pyrites (Fe 3 S 4 ) found in hexagonal crystals of a magnetic character. Ferrous Sulphide (FeS) is a nearly black compound, insoluble in water, and in a fused form is used for gener- ating hydrogen disulphide by the action of acids thereon. It also finds employment for generating sulphur dioxide by burning, in the sulphite process of preparing wood pulp. Ferrous Oxalate (FeC 2 O 4 2H 2 O) can be obtained in the form of pale yellow crystals, insoluble in water, and is used as a photographic developer. Ferrous Iodide (FeI 2 4H 2 O) is a crystalline body soluble in water, and is used in the manufacture of alkali metal iodides. Ferrous Fluoride (FeF 2 8H 2 O) is a heavy white substance used in ceramics and in the manufacture of alkaline fluorides. (See also Ferrocyanides and Prussian Blue.) IRON PYRITES Iron sulphide. (See Pyrites.) " IRONAC "- A proprietary, hard, silicon cast iron alloy, advocated for use in making chemical plant to withstand the corrosive action of acids. IRONE A methyl ketone (C 13 H 20 O) constituting the odorifer- ous constituent of the iris root, and possibly that of the violet : it can be prepared from citral. IRONSTONE See Iron. 276 IRRIGA TIONISOMERISM IRRIGATION is a process often employed for the disposal of sewage, and consists in allowing it or the effluent from it (after preliminary treatment or deposition of the more solid parts) to slowly drain off or filter through the land, over which it should be fairly evenly distributed. A light loamy soil is the most suitable, and great purification is effected, whilst the land is, at the same time, fertilized for the growth of cereals and vegetables. The nature of the purification that occurs is explained under the heading of Nitrification. As supplies of suitable land are not generally available, specially prepared bacterial filter-beds of ashes or charcoal and other materials have recently come into more general use. (See Nitrification and Sewage.) ISAROL A substitute for ichthyol (made from bituminous schist found in the Tyrol) used as an irritant in skin affec- tions. ISATIN (C 8 H 6 NO 2 ) A synthetic reddish-yellow crystalline substance, fairly soluble in hot water, ether, and alcohol, which can be prepared by the oxidation of indigo with nitric acid and is convertible into aniline by the action of potash. Its melting-point is 200 C., and it is used in dyeing. ISINGLASS (Ichthyocoll) A pure commercial form of gelatin made from the internal membranes of the bladders of the sturgeon, and used as an adhesive, also for clarifying wines, beers, and other preparations. An inferior sort is made from fish bones. (See Fish Glue.) ISOLOGOUS Having similar proportions or relations, as, for example, groups of homologous terms in which radicals, by combining with a series of similar elements, produce other series of similar compounds. ISOMERISM Substances composed of the same number of the same atoms but differing in molecular construction and properties are described as isomeric. Thus, ordinary alcohol and methyl ether have the same percentage composition and molecular formula (C 2 H 6 O), but are perfectly distinct substances, the constitutional formulae being respectively C 2 H g HO and (CH 3 ) 2 O. There are many such cases, par- ticularly amongst organic compounds, and notably in connection with the bodies known as terpenes that is, the hydrocarbons forming the chief constituents of the various essential oils all of which have the common formula C 10 H 16 , and yet differ largely in their chemical and physical ISOMERISM ISOTOPES 277 ISOMERISM (Continued) properties. They are therefore described as physical isomers. Varying amounts of heat are consumed in the formation of any two isomeric bodies, and so when decom- posed, there is a corresponding difference in the evolution of heat, showing that varying amounts of energy are required to build up the different molecular structures of isomeric bodies. Stereo-isomerism Isomerism arising from the rearrange- ment in space of the atoms or radicals in a molecule round a central polyvalent atom. Thus two compounds may contain the same atoms and radicals, and have identical chemical and physical proper- ties, and yet differ in their action upon polarized light. In the case of active carbon compounds, these atoms and molecules are four in number, and if they are imagined to occupy the corners of a tetrahedron containing the quadri- valent carbon at its centre, then it will be found that such an arrangement necessitates two "stereo" or space isomers, which correspond to the positive and negative varieties of the compound. Valeric acid (C 5 H 10 O 2 ), for example, apart from its other modifications, possesses two stereo-isomers, and the groupings in this case are the four different radicals H, CH 3 , C 2 H 5 , and CO 2 H. (See Polymerism and Allo- tropy.) ISOMORPHISM See Crystallization. ISOPRENE (C 5 H 8 ) A volatile liquid hemi-terpene, yielded by the destructive distillation of pure rubber, also obtainable from turpentine by the action of heat, and which by contact with certain reagents, such as hydrochloric acid, becomes converted partly into rubber. It is colourless, boils at 37 C., and is of interest in connection with the attempted synthesis of rubber on a commercial scale. (See Rubber.) ISOTOPES A term introduced to explain the apparent exis- tence of very nearly allied but non-separable forms of chemical elements, the general chemical properties being identical, but exhibiting variation in their atomic weights, or mass, or molecular arrangement. Thus it is supposed that magnesium, silicon, and chlorine, in addition to neon, are mixtures of isotopes ; further, that nickel, copper, zinc, mercury, and other of the elements, are really mixtures of isotopes. Ionium and thorium are said to be isotopes. Many of the conclusions of the investigators of these 278 ISOTOPES JA SPER ISOTOPES (Continued) matters are based upon radio-active evidence, and others upon the separation of gases by diffusion, but much remains to be done before the subject and the electron constitution of matter can be regarded as satisfactorily established. (See Atoms, Radio-activity, Protyle, and Spectroscope.) IVORY Essentially dentine ; the main constituent of all teeth, containing about 57 to 60 per cent, calcium salts (chiefly phosphate) and 40 to 43 per cent, organic matrix. IVORY BLACK A fine velvety carbonaceous black, largely composed of mineral matter (65 to 75 per cent.), including calcium phosphate, prepared by carbonizing ivory-turnings and waste, and used by copper-plate printers in making their ink, also as a decolourizing and filtering agent. " IZAL " A proprietary disinfectant, being a ready prepared emulsion of phenoloids. JABORANDI See Pilocarpine. JADE Several distinct minerals are known by this name, the true jade being naphrite, an anhydrous double silicate of calcium and magnesium. Jadeite, which resembles it, is a silicate of aluminium and sodium. Jade is greenish-white to deep green in colour, is a favourite material for making ornaments and amulets, and is nearly as hard as quartz. It is extensively found in China, New Zealand, Eastern Turkestan, Siberia, and the Philippine Islands. JALAP The root of the plant Ipomoea purga (Off. Exogonium purga U.S.), which grows in Mexico, and is cultivated in India. It furnishes about 10 per cent, glucosidal resins, containing about 90 per cent, convolvulin (C 31 H 50 O 16 ) and about 10 per cent, jalapin (C 34 H 56 O 16 ). The resin con- stitutes a powerful purgative. JAPAN A lacquer for metallic and wooden articles, made by heating a mixture of linseed oil, litharge, and Prussian blue, thinned with turpentine or naphtha. JAPAN WAX See Waxes. JAPANNING A sort of varnishing or lacquering in which the Japanese excel, consisting in heating the varnished articles, after application of each coat, in an oven to a high temperature. Ivory black and anime varnishes are used amongst other materials, colours being introduced as and when required. JASPER A kind of quartz. (See Silica.) JATROPHAKAUREI GUM 279 JATROPHA A genus of euphorbiaceous plants, the root of one of which (Jatropha manihot) yields arrowroot. JAVELLE See Eau de Javelle. JET Supposed to be wood in an advanced state of bitumeni- zation (lignite), abundant in the upper lias shale near Whitby in Yorkshire. It is also found in Colorado, the island of Skye, and various parts of the European continent, and is used as fuel and for making ornamental articles. It is of varying hardness and of sp. gr. about i'3. "JEYES' FLUID" A disinfectant made from coal tar prin- ciples, miscible with water. JUNIPER Coniferous plants, of which about twenty species are known (including Junipents communis and /. Phoenicia), the berries of which yield upon distillation with water, a volatile essential oil, of sp. gr. 0*865 to 0*882 ; iodine value, about 285; saponification value, 14 to 15; and refractive index, 1*472 to i^SS. It is somewhat soluble in alcohol and ether, and is used for flavouring gin and hollands. JUTE The bast fibre of the Corchorus capsularis, the culture of which is chiefly carried on in Bengal. It is extensively manufactured in Dundee, and is woven in India into gunny bags and cloth, which are largely used in the Southern States of America for cotton packings. It is also used in the manufacture of carpets and various tissues, twine, and paper. KAINITE See Potassium. KAOLIN (Terra Alba, China Clay, White Bole) is not only used in ceramics and in compounding some pigments, but also for mixing with graphite in pencil-making. Its general formula may be regarded as Al 2 O 3 ,2SiO 2 ,2H 2 O. (See Clays.) "Emol Keleet" is a refined preparation of kaolin used for pharmaceutical preparations.* KAPOK The Malay name given to the cotton-like down produced in the seed-pods of the tree of that name and extensively used in making life-saving jackets, etc. The dried seeds yield about 24-5 per cent, of oil. " KARBOS " A char made from charred sawdust purified by acid treatment, and admixed with animal carbon ; used for decolourizing. KAURIE GUM A product of the kaurie pine of New Zealand. There is a large deposit of kaurie gum peat in the soil of the buried kauri forest in New Zealand, and a considerable industry is carried on in the extraction of the gum and associated oils, A ton of the peat yields 280 KAURIE GUM KELP KAUEIE GUM (Continued) about 10 per cent, of gum and gives by distillation about 64 J gallons of oil, from which motor spirit, a solvent oil, a turpentine substitute, and paint and varnish oils are extracted. The sp. gr. of kaurie is 1*05 and the melting- point about from 182 to 232 C.; it is used in varnish- making and the preparation of dental compounds. (See Dammar and Resins.) KELP The ashes of burnt seaweeds, containing sodium carbonate, sulphate, and sulphide, together with the chlorides . of potassium and sodium, and insoluble substances com- prising calcium carbonate, silica, and alumina. Kelp was at one time used for the extraction of both alkali and iodine, the latter being recovered from the mother-liquor remaining after the crystallization of the salts from the extracted ashes. Two published analyses give the per- centic parts as follows : Potassium sulphate ... ... 8 -0-19-0 Soda as carbonate and sulphide 8-5- 5-5 Potassium and sodium chlorides 36-5-37-5 53-0-62-0 soluble part. 47-0-38-0 insoluble part. In one process, the dried kelp is fed into a retort kept at a temperature of about 980 C. to obtain oil, creosote, ammonia, etc., by distillation, and the charred residual mass is cooled, ground and lixiviated, first of all with a concen- trated brine, fresh water being used for the final extraction. The pressed coke is saturated successively with hot hydrochloric acid and water, and is afterwards used as a decolourizing agent. After removal of trie sulphates from the brine liquor, it is heated in a vacuum pan to a certain point of concentra- tion and then transferred to a vacuum crystallizer, in which the potassium chloride deposits. Upon further concentra- tion the sodium chloride separates, whilst from the mother- liquor iodine is obtained. In another process, the kelp is fed into one end of a rotary kiln, in which it encounters a flame of burning oil from the other end, thus producing a charcoal-like mass which is subsequently quenched, ground and leached (lixi- viated), or it may be burned to a grey loose ash with a potassium content equal to about 35 per cent. K 2 O. About 8 Ibs. iodine can be extracted from a ton of Scotch kelp. KERATIN KIESELGUHR 281 KERATIN A gelatinous substance obtained from hoofs, nails, and hair of animals. KERMES The dried bodies of a female insect (Coccus ilicis L.), collected in Africa and some eastern parts of Europe, * and used for dyeing scarlet " fez " skull-caps, but the colour has less bloom than that given by cochineal, and is chemic- ally related to carminic acid. KERMES (Mineral) A mineral form of antimony sulphide. "KEROL" A proprietary phenoloid disinfectant liquid which emulsifies with water. KEROSINE A mineral illuminant oil distilled from the natural petroleum deposits in America, free of gasoline, naphtha, and heavy oils. Sp. gr. about i -440 and boiling-point about 230 to 240 C. KETONES A class of organic bodies, produced by the oxidation of the secondary alcohols. They are nearly related to the aldehydes, from which they may be considered as derived by the displacement of H in the COH group by the alcohol radicals. Thus common ethyl aldehyde (C 2 H 4 O or CH 3 COH) becomes CH 3 CO(CH 3 ) the formula of dimethyl ketone, or, as it is commonly called, acetone (C 3 H 6 O) which is the lowest member of the series. Again, iso-propyl alcohol by oxidation, yields acetone by the withdrawal of two hydrogen atoms C 3 H 8 O or CH 3 CH(OH)CH 3 + O = CH 3 (CO)CH 3 (Acetone) + H 2 O. " KHARSIVAN "The name of a British make of salvarsan. KIESELGUHR (Infusorial Earth, Tripolite) A soft, white, earthy deposit of hydrated silica, being the siliceous skeletons of minute aquatic plants known as diatoms, found in Germany, the United States, and many other parts of the world. It is generally associated with earthy impurities, and contains from 65 to 87 per cent. SiO 2 , 2-3 to 11*7 per cent. A1 2 O 3 , up to 3 per cent. Fe 2 O 3 , small proportions of the oxides of calcium, magnesium, potassium, and sodium, and from 5 to 14 per cent, water. It is of great absorbent capacity, capable of taking up about four times its own weight of water and having a sp. gr. of about 0-33. It is largely used as an absorbent for carrying liquid petroleum, in the manufacture of dynamite, as a filtering material, in ceramics, as an abrasive, cleanser, and polishing agent, and in compounding mixtures for boiler coverings, etc. (See Silicon.) 282 KIESERITE KRYPTON KIESERITE Mineral magnesium sulphate (MgSO 4 ,H 2 O) found in the Stassfurt salt deposits. KIMMERIDGE CLAY or SHALE A deposit found under the sands beneath the Portland stone of Dorsetshire and else- where, abounding in animal and vegetable matters. It- is used to some extent as fuel and yields on distillation petroleum-like products. KINGZETT'S SULPHUR CANDLES See Sulphur. KINO The concreted (inspissated) juice of at least four varieties of trees, used as a drug, being of an astringent character. African kino, or gummi gambia, comes from the Pterocarpus eyinaceus ; the Asiatic kind from Pterocarpus marsupium ; the New Holland variety from the Eucalyptus resinifera ; and the American kino from Coccoloba urifeva. The African kino is particularly rich in tannin, and is used for tanning purposes and in the textile industry. KIPP'S APPARATUS See Gas Generators. KIRSCHWASSER An alcoholic liqueur obtained by ferment- ing and distilling pulped cherries. KISH Crystalline graphite deposited in iron furnaces from molten iron upon cooling. KNOPPERN (Knopper Galls) A tannin material in the form of excrescences produced by insects (Cynips calicis) upon the immature acorns or flower cups of certain species of oak principally Quercus cerris of the Slavonic plains and known as " sisarca " and " gubacs." KOKA-SEKI A variety of pumice found in the Niijima Islands, used as a building material and for the construction of reinforced concrete barges, etc. KOLA (COLA) NUTS (Soudan Coffee) From the seeds of Cola acuminata, containing caffeine. " KOLLAO "See Lubricants. KOUMISS Fermented mare's milk used in Tartary as a vinous food ; something similar is said to be made in the Orkneys. An intoxicating spirit called " rack " is distilled from koumiss. KRAMERIA See Rhatany Root. KRYPTON (Kr) Atomic weight, 82*92. A very rare elemental matter recently isolated from liquefied air, and present in the air to the estimated extent of i part in 1,000,000. It is a colourless and inert gas and no chemical compounds of it are known. KUPFERNICKEL-LACTIC ACID 283 KUPFERNICKEL See Nickel and Arsenic. LABORATORY A simple chemical laboratory (workshop) con- sists essentially of a working bench or table about three feet from the ground, fitted with drawers and a shelf running along the back, upon which can be placed the chemical solutions (reagents) which are more or less in daily use. The bench should be provided with either a lead-lined wooden or a porcelain sink ; a water-supply pipe with one or more taps ; also a gas-supply pipe with two or three T-piece connections and taps, to which the various lamps and burners ordinarily used can be attached. In cupboards or on a shelf below, may be placed the larger pieces of apparatus and supplies of chemicals that are only occasion- ally wanted, whilst the drawers in the bench are useful for the storage of small appliances and requisites. LABRADORITE (Labrodite) A mineral of the lime-soda felspar order which takes a beautiful polish and exhibits changing colours (iridescence). LAC See Shellac. LACMOID (Resorcinol Blue) An indicator used in volumetric analysis ; prepared from resorcinol by treatment with sodium nitrite. LACQUER Varnish consisting of shellac dissolved in alcohol and coloured as desired with saffron, annato, or dragon's blood, etc. LACTIC ACID (C 3 H 6 O 3 ) results from, and is largely manu- factured by, the bacterial fermentation of milk, cane, or grape sugars, using the lactic bacilli which cause the acidity of soured milk. As thus made from starch, milk, or sugar, the acid is neutralized as the fermentation proceeds (at a temperature of about 34 C.) by addition of calcium carbonate, and the solution of calcium lactate is subsequently concentrated and decomposed with sulphuric acid. The pure liquid acid has a sp. gr. of about i'2485, is soluble in water and alcohol, and is used in the leather and textile industries, and in mordanting, etc. It is best known in a state of solution, but can be obtained in a crystalline form which melts at 18 C. It is also produced by the action of caustic potash solution upon grape or cane sugar with heat. For commercial purposes, lactic acid is prepared of 50 per cent, and 60 per cent, volume, and of 50 per cent, volume strength for edible ap- plications. Upon heating, lactic acid is partially converted into 284 LACTIC ACIDLANTHANITE LACTIC ACID (Continued) lactide (C 6 H 8 O 4 ) its anhydride and when heated with dilute sulphuric acid it splits up into acetaldehyde and formic acid. All the lactates are soluble in water. Lactic acid is said to be rapidly replacing the more expensive citric and tartaric acids in the compounding of soft drinks and in other industrial applications in the United States of America, and a small addition is stated to improve the quality of beer of low alcohol content by combining with the amides and amino-acids. LACTOSE or MILK SUGAE (C 12 H 22 O n ,H 2 O) The sugar contained in milk (sugar of milk). It can be obtained in a crystalline state, and is prepared on a considerable scale in Switzerland and elsewhere from the whey obtained in cheese-making, by concentration and crystallization. It is sweet, soluble in water, and used in the preparation of infants' foods. L^VULOSE See Fructose. LAKES The pigments obtained by precipitation from dye- stuffs and colouring matters. Aluminium hydroxide (A1(HO) 3 ) enters into combination with many soluble organic colouring matters, thus precipitating them as so- called " lakes " in calico printing and dyeing. (See Alu- minium.) The aluminium hydroxide acts as the mordant, and the same dye can give rise to different coloured lakes according to the nature of the mordant that is used. The lakes produced from certain dyestuffs are useless as pig- ments owing to their hard and horny nature, but if produced on a suitable base or " extender," such as barytes, china clay, blanc fixe, etc., this difficulty is overcome. Lakes are also used in the preparation of some lithographic and printing inks. (See Dyes and Dyeing.) LAMP-BLACK A finely divided carbonaceous deposit result- ing from the imperfect combustion of natural gas and lamp and other oils and fatty substances. The blackening of the glass chimney of a paraffin lamp is due to the deposition of lamp-black. It is manufactured for use in making blacking, black paint, and printer's ink. (See Carbon.) LANARKITE A natural basic lead sulphate (PbSO 4 ,PbO). LANOLINE See Adeps Lanse. LANTHANITE A mineral containing lanthanum carbonate associated with cerium carbonate. LANTHANUM LAUGHING GAS 285 LANTHANUM (La) Atomic weight, 139; sp. gr., about 6-155; melting-point, about 810 C. A rare element of the cerium group, found in cerite, allanite, and lanthanite, also in orthite in Greenland, and in association with other elements in gadolinite (ytterbite). It is a metal of lead-grey colour, and decomposes water slowly with the evolution of hydrogen. It can be prepared by the electrolysis of lanthanum chloride. The salts of lanthanum in solution are colourless, and when precipitated with a solution of potash or soda a bulky, gelatinous hydroxide (La(OH) 3 ) is formed. Lanthanum forms two oxides (the better known of which is La 2 O 3 , and both of which are insoluble in water), a chloride known in the anhydrous state (LaCl 3 ) (which is soluble in alcohol, and in a crystalline form in combination with water), also a number of other compounds, including the nitrate (La(NO 3 ) 3 6H 2 O), the sulphate (La(SO 4 ) 3 9H 2 O) (both of which are crystalline salts soluble in water), and the carbonate La 2 (CO 3 ) 3 .3H 2 O, which is used in making incandescent gas mantles. LAPIS LAZULI A translucent fine, blue, native compound silicate of aluminium, calcium, and sodium, found in crystalline limestone on the Indus, and in granite in Persia, China, and Siberia. It is highly valued as a beautiful mineral for vase-making, and at one time, ultra- marine was prepared from it. LARD The fat of the hog, containing a large proportion of olein with other glycerides. (See Fats.) LATENT HEAT is the heat absorbed in a state of physical change, such as that of solid ice to liquid water. This particular change renders latent that amount of heat which would serve to raise the temperature of the same weight of water through 79 C. (See Heat.) LATEX A milky juice produced in plants which coagulates into a gelatinous mass in cavities. This gelatinous sub- stance is called cambium, and is supposed in certain cases to precede the formation of cells. Gutta-percha is the coagulated product of latex from the Isonarda percha tree. LAUDANUM Tincture of opium, prepared by dissolving granulated opium in dilute alcohol. LAUGHING GAS or NITROUS OXIDE See Nitrogen Com- pounds (p. 338). 286 LAUREL OIL LEAD LAUREL OIL A bright, yellow, volatile oil of aromatic odour ; soluble in alcohol, ether, and chloroform ; distilled from the leaves of Laurus nobilis, and used in medicine. Its sp. gr. is 0*924. LAUBIC ACID (C 12 H 2 4O 2 ) A member of the fatty acid series and a notable constituent of oil of laurels or fat of the bay- tree (Laurus nobilis). It can also be obtained from pichurim beans and cocoa-nut oil. It melts at 43 C., and is soluble in hot alcohol. LAURITE A very rare mineral combination of ruthenium as sulphide (RuS 2 ). LAVA The fused material thrown out by volcanoes when in action, largely consisting of silicate of aluminium. LAVENDER (SPIKE) OIL The yellowish essential oil of Lavandula spica L., consisting in part of a terpene ; sp. gr., 0-905 to 0-920; optical rotation, o to +3; soluble in alcohol, ether, etc., and used in perfumery and liniment-making. LAVENDER-FLOWER OIL is distilled from the flowers of Lavandula officinalis, and is more fragrant than the spike oil. It is nearly colourless, has a sp. gr. of 0-885 to 0-897, optical rotation - 5 to - 8, is soluble in alcohol, ether, etc., and is used in perfumery. It contains linalool, linalyl acetate, geraniol, and cineol. LAZULITE (Azurite) A mineral crystalline form of hydrated phosphate of aluminium, magnesium, and iron. LEAD (Plumbum, Pb) and its Compounds Atomic weight, 207; sp. gr., 11*3; melting-point, 327-4 C. Lead occurs naturally, for the most part, in the form of galena or lead sulphide (PbS), the U.S.A., Mexico, and Spain providing the principal supplies. It also occurs as carbonate (PbCO 3 ) in cemsite and in other combinations it is present in anglesite (PbSO 4 ), in lanarkite (PbSO 4 ,PbO), etc., whilst a new, rich mine has been recently discovered in Burmah. The production of lead ores on certain horizons of the lower carboniferous formations in England and the Lower Palaeozoic formations in Great Britain decreased steadily from 80,850 tons in 1877 to 14,784 tons in 1918. In 1913 the world's production of lead was 1,700,000 tons. Lead is produced by several processes, one of which consists in roasting lead sulphide in a reverberatory furnace at a certain temperature, whereby some of it is resolved into lead sulphate (PbSO 4 ) and some into lead oxide (PbO), a part of the sulphur being burnt off as sulphur dioxide LEAD 287 LEAD (Continued) (SO 2 ). Upon increasing the temperature, a further change takes place in the mixture which still contains some lead sulphide, and metallic lead results from the two following interactions : .! + PbS = 2Pb + 2SO 2 The metallic lead thus produced is subsequently refined by another process. In other metallurgical processes, a saturated solution of salt, which is a good solvent for lead chloride and lead sulphate, is used, and from the solutions so obtained (when not contaminated with other elements) the oxide is pre- cipitated by the action of lime, or (when contaminated with other elements) by electrolysis, the metallic lead being obtained from the oxide by reduction. From recent investigations of metallic lead as obtained from radio-active minerals that is, minerals containing uranium and radium it would appear that there are, at least, two kinds (isotopes) of lead viz., the ordinary type as found in non-radio-active minerals, and another which is assumed to be produced by the decomposition of uranium, this radio-active form showing a slightly higher (o'O5 C.) melting-point than that of ordinary lead. The density of the uranio-lead was originally reported as below that of the ordinary metal, as also its atomic weight (206) . A specimen of lead prepared from a Norwegian thorite (from Langesundfiord) quite recently examined, containing 30' i per cent, thorium, 0*45 per cent, uranium, and 0-35 per cent, lead, appeared, however, to have an atomic weight of 207-77, the highest value yet assigned to this element, so that the matter cannot be regarded as definitely settled, and more delicate processes of analysis are required to clear up the existing doubt as to the existence of distinct metallic leads. Lead is a heavy, bluish- white metal, very soft in character, but not very ductile or tenacious, and it readily tarnishes upon exposure to the air. Owing to its soft character it is easily worked, and it is consequently employed very largely for lining wooden cisterns, making water-pipes, gutters and roofing, as also shots, and in the preparation of white lead and various alloys. It can be hardened by alloying it with a small proportion of metallic sodium. Type-metal consists, in part, of lead (alloyed with antimony and tin), and lead is also used in the manufacture of fusible 288 LEAD AND ITS COMPOUNDS LEAD (Continued) metal, pewter, and other alloys. Solder, as used by plumbers and tin-plate workers, is a mixture of lead and tin in proportions varying with the particular applications to be made of it, whilst so-called pot-metal is an alloy of lead and copper. Many of the compounds of lead are largely used in the arts and manufactures. White-Lead, which is used so much in compounding paints and putty, is a mixture of lead carbonate and hydrated lead oxide. Of the various processes for making white-lead, the oldest and best is the so-called Dutch process, which depends upon the use of acetic acid in association with moist air and carbon dioxide. The lead, prepared in a way to present as large a surface as possible, by being cast into rough gratings or grids, is placed on pots over a bed of spent tan-bark, acetic acid being placed in the pots. The acid is slowly vaporized by the heat of the fermenting tan, and this, acting upon the lead, forms a compound basic acetate, which undergoes further changes by the carbon di- oxide evolved from the fermenting tan, and the action of air and moisture, finally resulting in the production of white- lead of commerce (2PbCO 3 ,Pb(HO) 2 ). In all, five oxides of lead are known, all of which are insoluble in water (Pb 2 O, PbO, Pb 2 O 3 , Pb 3 O 4 , and PbO 2 ), but of these the PbO (litharge) and the Pb 3 O 4 (red-lead) are the more important. Lead Hydroxide (2PbO.H 2 O) is produced in the form of a white, bulky precipitate by adding an alkaline hydrate solution to a solution of a lead salt. Lead Monoxide (PbO) is formed by strongly heating the metal in air, or by roasting nitrate or carbonate of lead, and under the name of litharge it is used in the manufacture of certain qualities of glass and pottery, acid-resisting cements and lakes, and in connection with that of oils and varnishes. Red-Lead (Minium) (Pb 3 O 4 ) results from the prolonged heating of the monoxide in contact with air at about 450 C., and is a scarlet-coloured powder which varies to some extent in colour and in composition as prepared for com- mercial uses, containing as it does varying proportions of other oxides of the metal. It also occurs in natural deposits, and is largely used in the manufacture of ceramics, flint glass, and as a pigment. LEAD AND ITS COMPOUNDS 289 LEAD (Continued) Lead Chloride (PbCl 2 ) is a white, crystalline substance which is precipitated in a curdy form from solutions of lead salts by the addition of hydrochloric acid, and can be obtained by dissolving the monoxide or lead carbonate in hot hydrochloric acid, from which solution it crystallizes out on cooling in long lustrous needles. It is soluble in boiling water (i part in 25 parts). An oxychloride or a compound of chloride and oxide in a hydrated condition known as Pattinson's white -lead is obtained by heating lead chloride in air and has a com- position approximating to PbCl. 2 ,PbO,H 2 O. Lead Sulphate (PbSO 4 ) is a white, insoluble body resulting from the precipitation of lead salts in solution, by sulphuric acid or solution of a sulphate, and is used to some extent in compounding paints. Lead Nitrate (Pb(NO 3 ) 2 ), a crystalline substance very soluble in water, is made by dissolving litharge in nitric acid, and finds many industrial applications. Lead Iodide (PbI 2 ) is a beautiful yellow insoluble com- pound used in bronzing, mosaic gold, printing, etc. Lead Sulphide (PbS) is a black compound found native as gakna, and can be prepared by the action of hydrogen sulphide upon solutions of lead salts. It is insoluble in water, and is used in ceramics. Lead Chromate (PbCrO 4 ) is found in mineral form as cvocoisite, and is a beautiful chrome-coloured insoluble com- pound which finds use as a pigment. Lead Acetate (Sugar of Lead) (Pb(C 2 H 3 O 2 ) 2 .3H 2 O) is a white, crystalline, poisonous salt, soluble in water, which becomes anhydrous when heated to 75 C., and is made by the action of acetic acid on litharge (PbO). It is used in dyeing and printing cotton goods, in varnish-making, and in medicine. Commercially it is prepared in a number of grades of varying colour (white, grey, and brown) and purity. There are other acetates viz., the monobasic salt (Pb 2 O (CH 3 COO) ? ) and the tribasic (Pb(C 2 H 3 O 2 ) 2 2PbO.H 2 O) both of which find industrial applications, the last named being used in weighting silk and textile printing. Lead Antimonate (Naples Yellow) is insoluble in water and used as a pigment ; also for staining glass and china ware. 19 290 LEADLEGUMIN LEAD (Continued) Lead Borate (Pb(BO 2 ) 2 H 2 O) is insoluble in water and used in the varnish and paint trades as a drier. Lead Carbonate (PbCO 3 ) is a white, crystalline powder, insoluble in water, used in paint-making. Lead Oleate (Pb(C 18 H 33 O 2 ) 2 ) is a white, unctuous sub- stance, soluble in alcohol, ether, benzol, and turpentine, used in making certain varnishes and lacquers and as a paint drier. When a lead solution is submitted to electrolysis, the metal is deposited in crystalline form at the cathode in what is commonly known as the tree lead. All the compounds of lead are poisonous. LEAD ASHES The skimmings due to oxidation in melting down lead. LEAD PLASTER A mixture of lead soaps of fatty acids, pre- pared by heating olive oil with litharge or by heating a solution of lead nitrate with sodium linoleate ; used in medical practice as an external application and as a drier in varnish-making. LEATHER Prepared from animal hides by the action of tannins, the process being described as tanning, which is effected by chemical combination of the tannin with the gelatinous principles of the tissues employed. Artificial leather is the name given to a number of com- posite materials made of any suitable base such as cloth, felt, or paper coated with an embossed covering in imitation of grained leather, pyroxylin dissolved in amyl acetate admixed with castor oil being one of the solutions employed. Several varieties of nitrated cellulose can be used ; blown linseed and other oils can be used in place of or in addition to castor oil ; and a great variety can be made in the way of solvents, whilst pigments are often introduced to give colour and body to the coverings. (See Tanning.) LEAVEN is really bread which has commenced to decompose by a sort of fermentation, but the use of this stale bread for leavening fresh bread has been superseded by the general use of yeast. LECITHINE See Brain Matter. LEGUMIN (Vegetable Casein) The distinctive protein con- stituent of peas, beans, and lentils, of nutritive value and amounting to about 25 per cent, calculated on the dried products. (See Albumins and Proteins,) LEMON OIL LIGHT 291 LEMON OIL A pale yellow, limpid liquid of lemon odour, containing limonene, pinene, citral, and citronellal, of sp. gr. 0*858 to 0^859 and optical rotation +60 to +64, ex- pressed from the peel of the Citrus limonum. It is soluble in alcohol, ether, etc., and is used in perfumery, for flavour- ing, and in compounding some beverages. LEMON GRASS OIL See Verbena Oil. LENSES Concave and convex glasses that respectively lessen or enlarge objects examined by them. LENTILS Seeds of the leguminous plant Ervum lens, from which a flour can be prepared. LEPIDOLITE (Lithium Mica) A Moravian purple mineral con- taining lithium and aluminium in combination as silicates. LEUCINE (Amino-Caproic Acid) (C 6 H 13 NO 2 ) A decomposi- tion product of albuminoid bodies generally accompanying tyrosine in the animal economy. LEUCITE A crystalline mineral double silicate of aluminium and potassium (K.Al(SiO 3 ) 2 ). LEVIGATION The reduction of lumps and hard parts of substances to pulverulent form by grinding in water or other liquid. LEVULOSE (C 6 H 12 O 6 ) A form of glucose which results along with dextrose from the action of dilute acids upon sucrose (cane sugar). It turns the plane of polarization of a ray of light to the left. (See Carbohydrates and Saccharoses.) LEY A solution of caustic soda or potash in water. LIEBIG'S BULBS See Potash Bulbs. LIEBIG'S CONDENSERS See Retort. LIGHT Light in nature is chiefly derived from the sun, but is also furnished by other heavenly bodies. The glow-worm and the firefly have the power of giving out a light in the darkness, and, as is well known, decaying animal matter exhibits a pale phosphorescent light. The production of light by animals is stated to be due to the burning by oxidation of a substance named luciferin in presence of a catalyst called lucifemse, and the oxidation product can be readily reduced again to the original substance. In the case of Renilla, it is thought that the phosphor- escence produced at night by stimulation, is under the control of the nerve-net of the animal. 292 LIGHT LIGHT (Continued) The phosphorescence of the sea is light given out by countless bacteria present in the water. When a current of electricity is sent through an electric lamp it gives out light, because the electric current, en- countering a resistance in its passage through the filament of the lamp, becomes partially transformed into light. Lightning, as occurring in storms, is a form of light con- nected with electric discharges from the clouds. Light can also be produced by chemical means, many substances, such as phosphorus, magnesium, strontium, and sulphur, emitting light of different degrees and shades when burned in the air. In the ordinary combustion of fuel (wood and coal) light is also produced ; in fact, combustion of organic matter is always attended with production of more or less light and beat, whilst flame has been described as gas heated to such a temperature that it emits light as well as heat. Light can be produced by the rubbing together of sugar or quartz, or when quartz is rubbed by any material harder than itself such as topaz or sapphire or water-worn pebbles of corundum. It is also emitted during the act of crystalliza- tion of certain salts from their solutions, and exercises a con- siderable influence in respect of many chemical changes, particularly those which take place in animal and vegetable tissues. When a stream of oxygen mixed with hydrogen is ignited, the mixed gas burns without giving out any sensible amount of light ; but if the jet of burning gas be directed upon a piece of lime, the most brilliant light, or so-called oxyhydrogen limelight, is produced so soon as the lime becomes hot. We have another familiar instance of the power of solids to influence the light given out by flame in the so-called Welsbach mantle, in which the burning gas (which in itself would give what is practically a blue flame almost devoid of light) playing upon a surrounding mantle impregnated or charged with certain mineral oxides, develops an intense white light. A mixture of thorium oxide with a small pro- portion of cerium oxide is commonly used in preparing these mantles. (See Gas Mantles.) It is difficult to answer the question, What is light ? By some physicists it is regarded as essentially identical with electricity. It is not so much a thing as an effect, a state of matter that is to say, illuminated matter, varying, of course, with the medium through which it is rendered LIGHT 293 LIGHT (Continued) evident ; its revelation being dependent upon what are called undulations or vibrations similar to those of sound produced by blows upon metallic or other bodies and by musical instruments. When a gong is hit by a hammer, it is thrown into a state of excitement or vibration and sound is produced ; and in a similar sort of way, when a gas is ignited or when a solid body (as in the case of the limelight) becomes heated in a flame of gas, light is given out in consequence of the burning gas being thrown into a state of tremendous excitement or vibration. The light thus produced is quite distinct from the heat which acts as a first cause or incitement to its production. When a piece of phosphorus contained in a suitable holder is placed within a jar filled with oxygen at a tem- perature above 34 C., it takes fire, and emits a brilliant white light. As the light does not come from without, it must be the result of the chemical action that takes place between the phosphorus and the oxygen. That being so, it, or something that furnishes it, must be contained or locked up in the one or other, or both, of these substances, as explained in the section on Force (p. 205). As a matter of fact, heat always accompanies light, as in the case of the sun's rays. Light travels at a very great rate about 185,157 miles in a second and is only eight minutes in coming from the sun to the earth. It has been recently demonstrated by experiment that speech can be transmitted by the agency of light. Light is reflected when its rays fall upon a mirror that is to say, it is thrown back at an angle and may be thus made to show a brilliant spot upon a wall. White light is said to be made up principally of seven colours viz., violet, indigo, blue, green, yellow, orange, and red ; and if a circular piece of cardboard be painted with these seven colours in equal sections and made to rotate, or spin quickly, the several colours disappear to the eye, and the whole face of the disc appears to be white. The green parts of plants absorb carbon dioxide gas from the atmosphere under the influence of solar light, the carbon being assimilated or fixed in their tissues by chemical changes, oxygen being at the same time restored to the atmosphere ; this change materially assists in pre- serving the uniformity of composition of the air. These changes, however, do not take place when the light is excluded. Vegetable matter cannot make its green colour- 294 LIGHT LIGNIN LIGHT (Continued) ing-matter (chlorophyll) without light, and so celery, sea- kale, etc., are grown in a blanched state by being kept in the dark. A mixture of chlorine gas with hydrogen gas in certain proportions, undergoes no chemical change in the dark, but if exposed to sunlight, the two gases enter into combination with explosive violence. Again, the art of photography depends upon chemical changes brought about on the prepared (sensitized) paper or plate by the direct action of light upon chemicals placed on their surfaces ; solar light having the power of causing de- composition of the oxide, chloride, nitrate, or bromide of silver, for example, when these substances (with which their surfaces are variously prepared) are exposed to it under certain conditions. The bleaching of linen and other goods by exposing them to moisture and air is another well-known illustration of the influence of light in effecting chemical changes. Many chemical reactions are accelerated by light, and these effects are more marked in the presence of ultra- violet light than in the presence of light of shorter wave length. Radiant heat, light, and electricity are similar from a purely physical standpoint and they produce similar chemical changes. (See also Polarization.) LIGHTNING See Electricity and Light. LIGHT OIL See Coal. LIGNIN A constituent of wood, said to be composed of two substances of undetermined constitution and formulae (but represented as C 40 H 40 O n and C 54 H 48 O 18 ) resulting from the treatment of wood with 70 per cent, sulphuric acid. A better result is stated to be obtained by first of all saturat- ing the powdered wood with a mixture of acetone and ethylic alcohol and treating the product with strong hydro- chloric acid. The cellulose and other carbohydrates are dissolved and the lignin is left behind, amounting to some 28 per cent, of the (pine) wood, representing the micro- scopic structure of the wood cells. It is almost completely dissolved by digestion in 5 per cent, caustic soda solution at 170 C., and yields lignic acids by fusion with caustic potash. Lignin is supposed to result from changes in the cellu- lose forming originally the walls of the living cells of wood, so that the heart of a tree is composed largely of lignin as distinct from the soft, pithy living parts. LlGNlTE-LlMOtilTE i$$ LIGNITE A brownish-black natural deposit allied to coal, found in many parts of the world, which yields so-called paraffin oil upon distillation. It contains from 27 to 43 per cent, of carbon, and its calorific value is about half that of coal. The deposits in Holland and Italy have been largely worked since 1917. A recent examination of lignite from the Riebeck Montan Works yielded 15 per cent, of a quality of bitumen which was soluble in hot benzene and 8 per cent, of another quality which was dissolved at a higher temperature, a large part of the extractives being identical in composition with so-called Montan wax. The insoluble part yields the major portion in a soluble form on heating with alkali in solution, as so-called " humic acids" which are precipitable upon acidification of the alkaline extract. (See Montan Wax.) LIGNUM VIT-ffl The wood of Guaiacum officinale or of Guaiacum sanctum. It is employed to some extent in the form of shavings, raspings, and sawdust for the making of decoc- tions, and more extensively for making taps and vessels, being hard, strong and capable of withstanding the action of many liquids better than ordinary wood. LIME See Calcium. LIME (CHLORIDE OF) See Calcium. LIMELIGHT See Light. LIMES (OIL OF) The essential oil of the rind of Citrus limetta containing citral and limonene ; sp. gr., 0*882 ; optical rotation, 4-35 to +40; and refractive index, 1*484 to 1*485. It is soluble in alcohol, ether, etc., and used as a flavouring material and in perfumery, confectionery, etc. LIMESTONE See Calcium. LIMONENE Dextro-limonene (hesperidene, citrene, or car- vene). The oil of orange rind consists almost entirely of this terpene, which is also a constituent of carvene, dill oil, and citron oil. It boils at 175 C. Lsevo limonene is present to some extent in the oil of fir-cones, associated with other terpenes. Dipentene is inactive limonene. LIMONITE A mineral hydrated iron oxide bog iron ores ( 2 Fe 2 3 .3H 2 0). 296 LIMPID LINSEED OIL LIMPID Clear and transparent fluids, the particles of which exhibit great mobility or rapidity of movement. LINALOE OIL A Mexican distilled wood oil of colourless, fragrant character, containing linalool and geraniol, having a sp. gr. of from 0-875 to 0*890, soluble in alcohol and ether, and used in perfumery. LINALOOL (C 10 H 18 O) A liquid of boiling-point 195 C., isomeric with geraniol, occurring as linalyl acetate in the cacao-bean and the oils of lavender, coriander, neroli, and sage. LINARITE A crystalline, basic, cuprous lead sulphate mineral (PbS0 4 ,CuH 2 2 ). LINEN Cloth manufactured from the fibres of the flax stem. LINOLEIC ACID (C 17 H 31 .COOH) occurs as a glyceride in linseed, poppy, hempseed, and other drying oils, and as a constituent of some non-drying oils. (See Linseed Oil.) LINOLENIC ACID (C 18 H 30 O 2 ) occurs as a glyceride in linseed, hempseed, and some other drying oils, and is very oxidiz- able. (See Linseed Oil.) LINSEED OIL is expressed by pressure from flax seed (Linum usitatissimum), and is largely used in making paints, varnishes, linoleum, patent-leather lacquers, rubber substitutes, and soft soaps, while the residual cake is used for feeding cattle. The cake is known to contain hydrocyanic acid derived from a contained glucoside, but most of it is dissipated during the maceration of the seeds and by evaporation. Linseed oil has a sp. gr. of 0-932 to 0-938, a saponi- fication value of 185 to 195, and iodine value 171 to 200. It contains linoleic (linolic) acid (C 18 H 32 O 2 ) in combination with glycerine and is typical of the class of so-called " dry- ing oils," from their readiness to absorb oxygen upon exposure to the air, being changed thereby into a trans- parent, sticky mass. Linolenic acid (C 18 H 30 O 2 ) is said to accompany the linoleic acid as a constituent of the oil. A published description of linseed oil is to the effect that it consists of 85 to 90 per cent, liquid glycer- ides, containing about 5 per cent, oleic acid, 15 per cent, linolic acid, 15 per cent, linolenic acid, and 65 per cent, isolinolenic acid, the remaining 10 to 15 per cent, being made up of glycerides of solid fatty acids, chiefly palmitic. When first expressed, the oil is pale yellow and not dis- LINSEED OIL LITHIUM 297 LINSEED OIL (Continued} agreeable in smell, but unless it is refined it quickly turns rancid, dark in colour, and repulsive in odour. It is soluble in alcohol, chloroform, carbon disulphide, benzol, and turpentine. H eating alone, under pressure, at a constant temperature greatly increases the viscosity and the iodine value decreases, while the saponification value remains unchanged. When boiled until it loses one-eighth of its weight, it thickens, becomes viscid, and dries quickly upon exposure to air. The oxidation of linseed oil by a current of air is facilitated by the use of a little manganese dioxide or other drier, and this process gives " body " and drying properties to the product. Saponified with alkalies, linseed oil gives soft soap of a thin character. Supplies come from many places, and Argentine has about 3,500,000 acres of flax under cultivation. Linseed yields by pressure aided with heat, about 27 per cent, of linseed oil. (See Paints and Varnishes.) LIPASE See Enzymes. LIQUATION The stage reached, when heating an ore or other metallic mixture containing ingredients differing sensibly in fusibility, at which the most fusible constituent melts and flows away from the mass. LIQUID AMBAR (Storax) An amber-yellow, thick oil or balsam produced from incisions made in a tree (Liquidambav styraci- folia) which grows in Louisiana, Florida, and Mexico. It is soluble in hot alcohol and ether, and is used in perfumery. (See Balsams.) LIQUOR AMMONITE A strong solution containing 35 per cent, of ammonia gas dissolved in water, having a sp. gr. of 0-882 at 15 C. LIQUORICE JUICE, as obtained from the roots of the Gly- cyrrhiza glabra and Gl. echinata, contains a sweet, amorphous substance, soluble in alcohol and hot water, named gly- cyvrhizin (C 24 H 3C O 2 ), which is said to yield glucose when boiled with dilute sulphuric acid. Spanish liquorice is used as a demulcent remedy for coughs, etc. LITHARGE See Lead. LITHIUM (Li) Atomic weight, 7 ; sp. gr., 0-59 ; melting- point, 1 80 C. Lithium is a somewhat rare element found in small quantities widely distributed in nature, in asso- 298 LITHIUM LITMUS SOLUTION LITHIUM (Continued) ciation with certain more or less rare minerals, including petalite, spodumene, and lepidolite (lithium mica), all of which are, in the main, silicates of aluminium. It is also found in several mineral waters which are extensively used for medicinal purposes. Lithium in the metallic form is the lightest known solid substance, and is obtained from the fused chloride by electrolysis ; it is of a soft character, and has a silver-like appearance, but quickly tarnishes when exposed to the air, so that it has to be kept in naphtha or kerosine. Like sodium it decomposes water at the ordinary temperature, lithium hydroxide being formed and passing into solution, whilst hydrogen gas is generated. Lithium oxide (Li 2 O) exhibits alkaline properties, and, in common with the carbonate, is used medicinally as an antidote to gouty complaints. The volatile lithium salts give a crimson tinge to flame. The following lithium compounds are among those best known : hydroxide (LiHO), carbonate (Li 2 CO 3 ) (only slightly soluble in water), chloride (LiCl), and phosphate (Li 3 P0 4 ). The hydroxide, chloride, bromide, citrate, and iodide are all soluble in water, the four last named being all used in medicine. The carbonate, citrate, and iodide are also used in compounding mineral water, whilst the fluophosphate and the fluoride are used in ceramics and enamels. LITHOPONE A white paint pigment having zinc sulphide, zinc oxide, and barium sulphate as chief basic constituents, prepared by strongly heating a mixture of zinc sulphide and barium sulphate, or one of barium sulphide and zinc sulphate, to redness. LITMUS A violet-blue colouring matter prepared from the lichens Lecanora tavtarea and Rocella tinctoria by treatment with ammonia and potash, and then fermenting the mass. LITMUS PAPER is absorbent filter or blotting paper stained by soaking (and subsequent drying) in a solution of litmus. Acid solutions turn this blue into red, and alkaline solutions restore the blue colour, so it is commonly used to determine the alkaline or acid nature of liquids. Litmus paper can be prepared of a neutral tint equally amenable to both reactions. (See Turmeric Paper and Volumetric Analyses.) LITMUS SOLUTION may be used for the same purposes as litmus paper. LIVER OF SULPHUR LUBRICANTS 299 LIVER OF SULPHUR An old name still used commercially in respect of a mixture of potassium sulphides as prepared by heating sulphur and potassium carbonate in a closed vessel. LIXIVIATE To extract, by solution, alkaline substances from materials containing them, such as black ash that is, crude sodium carbonate. (See Sodium.) LOADSTONE Magnetic ironstone. (See Iron and Elec- tricity.) LOAM Clay more or less mixed with sand or marl. LODE A vein or fissure in rocks filled with metalliferous deposit. LOGWOOD EXTRACT is made from the wood of a tree (Hamatoxylum campechianum) which grows in Central America and the West Indies, and yields its fine red colour both to water and alcohol the latter more readily. The colour left to itself turns yellowish and subsequently black. It is turned yellow by acids, while alkalies deepen it and give it a more purple hue. A blue colour can also be obtained from it by mixing with verdigris. It is chiefly used for black colours, to which it imparts great lustre, but it is also extensively used in compounding various colours on cloth and other stuffs. LUBRICANTS Preparations used to decrease the friction between opposed solid faces, which arises, as is sup- posed by some, from true cohesion. The solid varieties include natural and artificial graphite, talc, mica, and other substances, such as "flowers of sulphur" and white-lead, which are used for curing hot bearings. The natural graphite is usually of the so-called flake variety, and varies in size of particles from ^ in. and less than ^^ in., whilst the artificially produced kind is amorphous, and ground even finer than the natural product. The latter is sold under the trade names of " Aquadag " and " Hydrosol " when in admixture with water, and as " Oildag," " Oleosol," and " Kollag " when in admixture with oil. Generally speaking, solid lubricants are applied dry in cases where for special reasons it is inadvisable or not possible to use liquid or semisolid lubricants, although they are usually employed in admixture with oil or as ingredients in greases. " Aquadag " used as a cylinder lubricant has been found advantageous where solid friction occurs, as in worm-gear, 300 LUBRICANTS LYMPH LUBRICANTS (Continued) although equally good results have been obtained by the use of natural flake graphite ; and it has been concluded that the lubricating value of graphite depends upon its chemical purity. The lubricating value of oil depends upon something not yet properly understood ; it is not viscosity. What, how- ever, is required in a liquid lubricant is that it shall penetrate into the narrow spaces between journal and bearing, thus "wetting" or spreading over the surfaces which are in motion together. The function of a lubricant is to keep metal surfaces separate with a minimum expenditure of energy. Vegetable and animal oils possess greater value than mineral oils obtained from crude petroleum and coal tar, which are also used as lubricants in common with the so-called rosin oil, obtained by the destructive distillation of resin. They are generally graded in accordance with their specific gravities and viscosities. The so-called "germ process" of lubrication employs one or more fatty acids with mineral oil as the instrument of lubrication, i or 2 per cent, being incorporated according to chemical circumstances. This is said to reduce the coefficient of friction from 0-0084 to 0-0052 that is, some 25 per cent, on a friction-testing machine. Oils exhibit a rapid increase in viscosity with pressure, this increase being much greater for the mineral than for animal and vegetable oils. LUMBANG OIL See Candle-nut Oil. LUMINOSITY See Light and Flame. LUMINOUS PAINT See Calcium Compounds and Paints. LUNAR CAUSTIC Fused silver nitrate. (See Silver.) LUPULIN See Hop. LUTECIUM (Lu) Atomic weight, 175. One of the extremely rare, recently discovered elements of the yttrium group. LUTES Cements used to pack or seal the joints of vessels, varying in nature according to the chemicals concerned. LYE (LEY) A solution of alkali such as used in soap- making. LYMPH may be regarded as transuded serum of blood which has been reabsorbed from the tissues and carried back to the circulation by the lymphatics. It is alkaline, contains LYMPH MA GNESWM 301 LYMPH (Continued) about 5 per cent, solid constituents made up of plasma and white corpuscles, and is really diluted blood-serum, from which the tissues have taken up what they require for nourishment. " LYSOL " The name of a cresolic antiseptic prepared so as to be miscible with water, making a clear solution. MACE The arillus or envelope of the shell of the fruit of the nutmeg (Myvistica moschata), cultivated in the Molucca Islands and the tropics (East Indies, India, etc.), containing two varieties of essential oil. The seeds also yield a volatile essential oil, which forms a soapy mass with alkalies, but these oils are not to be confused with the fixed oil or butter called myristin which is expressed from the seeds. Mace is used as a condiment in cooking, having a more agreeable odour than nutmeg. MACE OIL A colourless or slightly yellow oil of aromatic odour, containing pinene, dipentene, etc. ; of sp. gr. 0*91 to 0-93, and optical rotation + 10. It is soluble in alcohol, ether, etc., and is used in flavouring. MADDER (Turkey Red) The pulverized root of Rubia tinctovia, an herbaceous perennial, which is cultivated in the Levant, France, and Holland, and grows best in warm climates. It contains a glucoside which yields by fermentation the beautiful red dye known as alizarin. It also contains pur- purin. (See Alizarin.) MAGENTA or FUCHSINE An aniline dye, being a compound of rosaniline with an acid, prepared by heating a mixture of nitro-benzene, aniline, and toluidine with iron filings and hydrochloric acid. It dyes silk and wool direct. (See Trimethy Imethane. ) MAGMA A thin paste. MAGNESIA See Magnesium Compounds. MAGNESITE See Magnesium. MAGNESIUM (Mg) and its Compounds Atomic weight, 24 ; sp. gr., 1*74; melting-point, 651 C. Magnesium is not found uncombined in nature, but exists abundantly in com- bination associated with calcium as a double carbonate in the form of the mineral dolomite. Magnesite or Greekstone is essentially magnesium car- bonate, and in some forms is nearly pure (MgCO 3 ), large deposits of which are found in Greece, Austria- 302 MAGNESIUM AND ITS COMPOUNDS MAGNESIUM (Continued) Hungary, and other countries. It is extensively used for making refractory bricks. Kieserite is magnesium sulphate (MgSO 4 ,H 2 O) and cavnallite is a double chloride of mag- nesium and potassium (MgCl 2 .KC1.6H 2 O), from which substance in a fused state, magnesium in a metallic form is chiefly produced by electrolysis. It has been seriously proposed to extract the metal from the magnesium salts contained in seawater in Norway, where water-power is readily available. Magnesium is a silver-white metal which tarnishes slightly upon exposure to the air, and readily takes fire when heated in the air, combining with the oxygen thereof and forming magnesium oxide (MgO). This burning is attended with a brilliant white light often used for photo- graphic purposes. It is used in pyrotechnics and in making some alloys. The metal is 35 per cent, lighter than aluminium, and has a tensile strength about twice of that metal. An alloy with 80 per cent, magnesium has been found to be possessed of excellent qualities for use in the construc- tion of motors for aeroplanes, automobiles, and electric tramcars. The addition of as little as 0-5 per cent, magnesium to many alloys, such as those of aluminium and copper, and copper and zinc, results in a remarkable age-hardening after quenching, said to be analogous to the hardening and tempering of steel. Acted upon by dilute acids, hydrogen is evolved and the corresponding salts of magnesium are produced in solution. The Oxide (MgO) occurs in nature in the mineral periclase, and is produced in the form of calcined magnesia when mag- nesium carbonate is subjected to a sustained heat. The product, which is white and light, is used as a cement owing to its double capacity of slowly absorbing carbon dioxide and moisture, also for heat insulating and, owing to its refractory character, is of peculiar value for the manufacture of crucibles and cupels for metallurgical purposes. Magnesium Sulphate or Epsom Salts (MgSO 4 7H 2 O) is readily obtained by the action of sulphuric acid upon dolomite and separation of the insoluble calcium sulphate which is simultaneously formed. It is a colourless, crystalline salt, soluble in water, used as a medicine, in fireproofing, MAGNESIUM MAIZE OIL 303 MAGNESIUM (Continued) and warp sizing cotton goods. It is also of value as a fertilizer. Magnesia Alba, of the pharmacists, is a varying mixture of magnesium carbonate and hydroxide, made by pre- cipitating a boiling solution of magnesium sulphate with a hot solution of sodium carbonate. It is used in fire- proofing and as a face-powder, etc. Magnesium Chloride is a deliquescent body very soluble in water, which can be obtained in crystalline form (MgCl 2 6H 2 O) as also in the anhydrous state (MgCl 2 ). It loses two molecules of water at 100 C., and is used for dressing cotton fabrics, fireproofing wood, etc. Magnesium Carbonate (MgCO 3 ), which can be prepared by adding sodium carbonate solution to one of magnesium sulphate, is a light, white, amorphous substance used in common with natural deposits of the carbonate in fire- proofing, making tooth-powders, and for preventing the formation of scale in boilers. Magnesium Citrate (Mg 3 (C 6 H 5 O 7 ) 2 .i4H 2 O) is a soluble, white salt used in medicine. Magnesium Hydroxide (Mg(OH) 2 ) is a white powder obtained by precipitation from a soluble magnesium salt by a solution of sodium hydrate, and is used in sugar-refining. Magnesium Nitrate (Mg(NO 3 ) 2 6H 2 O) is a white, crystal- line salt, soluble in water, used in pyrotechnics. Magnesium Fluoride (MgF 2 ) is a white, crystalline com- pound used in ceramics. MAGNET See Electricity. MAGNETIC IRON ORE (Loadstone) A native, crystalline compound ferroso-ferric oxide (Fe 3 O 4 ) having magnetic properties. MAGNETISM See Electricity. MAGNETITE Magnetic iron ore or loadstone (Fe 3 O 4 ) found in the United States of America and elsewhere. MAIZE OIL The germs of the maize plant (Zea Mays . L.) yield about 12 per cent, of corn oil, constituting a by- product in the preparation of maize starch. It is golden yellow in colour, and is composed chiefly of the glycerides of oleic, linolic, and palmitic acids. Its sp. gr. is 0-920 to 0-923, refractive index 1-4730 to 1*4735, saponification value 1 88 to 193, and iodine value in to 123. 304 MAIZE OILMALTASE MAIZE OIL (Continued) It is an edible oil, and is also used for lubricating and leather-dressing, etc. MALACHITE Native basic copper carbonate (CuCO 3 + CuO 2 H 2 ). (See Copper.) MALACHITE QUEEN An organic dye. (See Dimethylani- line.) MALE FERN OIL A nearly colourless oil containing hexyl and octyl esters of fatty acids, distilled from the rhizome of Dryopteris filix-mas marginalis. It has a sp. gr. of 0-85, is soluble in alcohol and ether, is used in medicine, and stated also to be used in compounding some varieties of gin and certain other liquors. MALIC ACID (C 4 HLO 5 ) occurs together with citric acid in unripe apples and in many other fruits, including goose- berries, cherries, bilberries, strawberries, mountain-ash berries, quinces, etc. ; also in the roots and flowers of many plants. A concentrated syrup left to evaporate, yields the acid in the form of colourless, odourless, and deliquescent needles or prisms, which melt at 100 C., and are soluble in water. Maple sap contains calcium malate. The malates are soluble in water. MALLEABILITY Admitting of being hammered out into thin sheets. (See Metals.) MALLET BARK The bark of Eucalyptus occidental^ of Queensland, containing about from 30 to 50 per cent, tannin; there is a commercial extract of 22 to 24 B., containing from 30 to 36 per cent, tannin. MALONIC ACID (C 3 H 4 O 4 ) is said to be contained in beetroot in combination with calcium, and may be prepared by the oxidation of malic acid. It crystallizes in white plates which are soluble in water and alcohol and melts at 132 C. MALT Barley or other grain, the starch of which has been converted into malt sugar by the enzyme diastase during germination in the process known as malting. Malt sugar (maltose, C^H^O^HgO) is a hard, crystalline body of little sweetness, very similar to grape sugar, and strongly dextro-rotatory. The maltose is in turn converted by another ferment (maltase) into grape sugar (C 6 H J3 O 6 ). MALTASE See Malt, MA LTINGMA NGA NESE 305 MALTING The preparation of barley or other grain by germination ready for brewing. (See Beer.) MALTOSE See Malt. MANDARIN OIL A yellow oil of sp. gr. about 0-85 and optical rotation + 70, expressed from the peel of the mandarin orange (Citrus bigavadia sinensis). It contains limonene, citral, etc., is soluble in alcohol and ether, and is used in perfumery, medicine, and for flavouring purposes. MANGANATES See Manganese Compounds. MANGANESE (Mn) and its Compounds Atomic weight, 55 ; sp. gr., 8; melting-point, 1,230 C. Manganese is found in nature chiefly in the form of pyrolusite a black oxide (MnO 2 ). There are two other native oxides viz., braunite (Mn 2 O 3 ) and hausmannite (Mn 3 O 4 ) while manganite is a hydrated oxide (Mn 2 O 3 H 2 O) ; manganese spar is carbonate (MnCO 3 ) and manganese blende is native sulphide (MnS). Manganiferous deposits occur abundantly in various parts of the world, including the United States of America, Canada, India, Brazil, Russia, and Cuba. Metallic manganese can be obtained by reduction of the oxide, using carbon in an electrical furnace, but is com- mercially prepared by using powdered aluminium for re- duction of the oxide in a refractory furnace, the mixture being ignited by means of a fuse. When required in a purer state, fused anhydrous manganese chloride is reduced by heating with metallic magnesium. It is of a reddish- grey colour, is soluble in dilute acids, and is extensively used in the metallic state, as a hardener of steel as made for certain special applications. An alloy of manganese and boron is used in making varieties of bronze, brass, and other alloys. Manganese ore the black oxide is largely used in the manufacture of chlorine by the action of hydrochloric acid, the chlorine in turn being used for the manufacture of bleaching powder (chloride of lime). (See Chlorine and Alkali Trade.) Oxides of Manganese Of these the most important members are represented by the formulae MnO, Mn 3 O 4 , Mn 2 O 3 , and MnO 2 , and the latter combines with some other oxides including calcium combinations forming unstable compounds, supposed to be represented by the formulas CaO,MnO 2 , CaCteMnO, and CaO,5MnO 2 , the manganese oxides acting the part of weak acids. Manganese Dioxide (MnO 2 ) can be prepared by adding a 20 3o6 MANGANESE AND ITS COMPOUNDS MANGANESE (Continued) solution of bleaching powder to a manganous solution or by roasting the monoxide in oxygen, and when dried and heated to redness it decomposes, becoming reduced to a lower oxide and giving off oxygen gas, thus : = Mn 3 O 4 +O 2 . It is largely employed in the manufacture of chlorine and as an oxidizing agent. Manganese Hydroxide (Mn(OH) 2 ), obtained by adding sodium hydrate to a manganous solution, as a nearly white gelatinous mass, becomes rapidly brown in colour by absorp- tion of oxygen from the air, thus passing into one of the higher oxides. It finds use as a pigment and in the ceramic industries. The higher oxides of manganese are useful sources of oxygen gas. Manganate and Permanganate of Potassium Two com- pounds of manganese with potassium and oxygen are well known as potassium permanganate (KMnO 4 ) and manganate (K 2 MnO 4 ), both of which are used as sanitary reagents, being valued on account of their oxidizing properties ; and there are corresponding sodium compounds, all of which are used in tanning and bleaching processes. By fusing black oxide of manganese together with potas- sium hydrate or carbonate, the green manganate is obtained by dissolving in water, whilst the crystalline red permanga- nate is now chiefly made by the electrolysis of the manganate solution at a temperature of about 60, using iron electrodes. Another method of manufacturing potassium perman- ganate consists in first of all making sodium permanganate by fluxing manganese ore with caustic soda (with or without the addition of sodium nitrate as an oxidizer) dissolving the product after grinding, in water, and treating the solution with chlorine and sulphuric acid, or alternatively with carbon dioxide, to transform the manganate into perman- ganate of sodium, and subsequently mixing the filtered concentrated permanganate liquor with the theoretical amount of potassium chloride, and again concentrating the mixture by heat, when the potassium permanganate crystallizes out upon cooling. The salts of manganese are flesh or pink coloured. Manganese Chloride (MnCl 2 ) is a soluble salt which can be obtained in crystalline form as MnCl 2 ,4H 2 O. MA NGA NESEMA NIOC 307 MANGANESE (Continued) Manganese Sulphate (MnSO 4 ) is obtained in crystalline form combined with water (MnSO 4 ,5H 2 O), and is used in ceramics and textile dyeing. Manganous Sulphide (MnS) is a flesh-coloured, insoluble substance, obtained by adding an alkaline sulphide solution to one of a manganous salt. Manganous Carbonate (MnCO 3 ) in precipitated form is a slightly rose-coloured, insoluble substance. Manganese Borate is a white powder, prepared by pre- cipitating solutions of manganese salts with one of borax, and has, when dry, the composition MnH 4 (BO 3 ) 2 H 2 O, losing its water of crystallization upon heating to 100 C., and at higher temperatures becoming Mn(BO 3 ) 2 . It is used as a drier for varnishes and in the oxidation of linseed oil, and is superior to lead driers but inferior to manganese dioxide, having, however, the advantage of not darkening the oil so much. Manganese Resinate (Mn(C 20 H 29 O 2 ) 2 ) A dark, nearly black substance prepared by boiling manganese hydroxide with rosin oil and water. It is soluble in hot linseed oil, and is used in common with manganese borate and man- ganese oleate as a varnish and oil drier. A manganese drier is also prepared by heating together common resin and manganese peroxide in certain pro- portions. Manganese Oleate (Mn(C 18 H 83 O 2 ) 2 ) is prepared by boiling manganese chloride with sodium oleate and water, and is a dark brown substance soluble in oleic acid. Manganese Acetate (Mn(C 2 H 3 O 2 ) 2 4H 2 O) A pale red crystalline salt, soluble in water; used in textile dyeing and manufacturing bistre. MANGANITE A crystalline manganese ore (Mn 2 O 3 ,H 2 O). MANGROVE A tannin material derived from the mangrove (Rhizophora mangle), growing in Mozambique, Parapet, Pomba Bay, and other parts of East Africa, also West Africa and Borneo, containing from 35 to 40 per cent, tannin. MANILLA Hemp fibre used for making certain qualities of cigarette and other papers. MANIOC The nutritious, starchy matter of Jatropha manihot from which cassava and tapioca are made in the West Indies. 308 MA NNA -MARGA RINE MANNA The dried juice or sap of the manna ash (Fraxinus ornus) which grows in Calabria, Sicily, and in the East. It contains from 30 to 60 per cent, of mannitol (C 6 H 14 O 6 ). MANNITE or MANNITOL (C 6 H 14 O 6 or C 6 H 8 (OH) 6 ) The chief constituent of manna. It is a white, crystalline body, soluble in water and to some extent in alcohol, and can be produced by the action of sodium amalgam on the mixture of dextrose and laevulose (C 6 H 12 O 6 ) that results from the action of dilute sulphuric acid upon cane sugar when boiled together. It is not very sweet, melts at about 165 C., and by the action of dilute nitric acid is converted into mannitic acid (C 6 H 12 O 7 or C 6 H 6 O(OH) 6 ). Chemically, it is regarded as a polyhydric alcohol derived from mannose, the last-named substance being stereo-isomeric with one of the glucoses comprehended in the monosaccharoses. It can be made to replace glycerol in fats. (See Olive Oil.) It can be distilled without appreciable decomposition, and does not ferment except under unusual conditions. (See Carbohydrates and Saccharoses.) MANURES See Fertilizers. MARBLE Crystalline limestone. (See Calcium.) MARC The refuse material resulting from pressure of seeds fruits, and herbs, from which extracts have been pre- pared. MARGARIC ACID (C^H^Ojj) The substance described under this name as one or the higher fatty acids, melting at 60 C., is now regarded as being, in reality, a eutectic mixture of palmitic and stearic acids. MARGARINE A butter substitute, manufactured on a large scale, consisting of fatty acids or oils from various sources, compounded with skim-milk sterilized by heating to 82 C., and sometimes inoculated with the butyric ferment (lactic acid bacilli) in order to give the blended mixture a butter- like odour. Cotton-seed, palm, cocoa-nut, and arachis oils are largely used, and in some cases animal fats, such as " premier jus " and lard, are admixed with the vegetable oils, so pro- portioned as to give a melting-point of about 20 C. Stearine, being more solid at the ordinary atmospheric temperature, is used when necessary to counteract the more liquid oils and to adjust the desired consistency. The fats produced by the hydrogenation process (see MARGA RINEMA STIC 3<*) MARGARINE (Continued) Hydrogen, p. 252) from whale, cotton-seed, and other oils are now extensively used to replace the animal fats pre- viously employed in making the best qualities. The process of making is somewhat as follows : The milk, after cooling to 10 C., is churned with the melted mixture of fats and oils at a temperature of 25 to 35 C. until thoroughly emulsified, then cooled, and after maturing, to allow the butyric ferment to do its work, kneaded to expel the excess of water over 16 per cent, which is the legal limit. It is essential that the oils ^ should be run slowly into the milk in the churn, to produce a fine-grained permanent emulsion of the oil-in-water type, as if the reverse method be used, an emulsion of the water-in-oil type results, and is not so satisfactory. (See Emulsions.) The English production of margarine in 1915 was esti- mated at 240,000 tons. MARJORAM OIL The essential oil of the aromatic herb Origanum majorana, containing terpineol and terpenes. It is soluble in alcohol and ether, and is used in perfumery and medicine. Its sp. gr. is 0-89 to 0-91. MARL Earth consisting of clay, chalk, and sand. MARMATITE A ferruginous variety of blende (in which the zinc is partly replaced by iron and manganese) occurring in the Broken Hill concentrates. "MARMITE" A food preparation resembling extract of meat, prepared from yeast. (See Proteins.) MARSH GAS A mixture of methane (CH 4 ) with carbon dioxide and nitrogen, formed in nature by the decomposition of organic bodies under water. (See Methane.) MARSH'S TEST See Arsenic. MASS Under constant conditions, the rate of chemical change is proportional to the mass of the reacting substances. MASSICOT A mineral form of lead monoxide (PbO) found in some of the United States of America. MASTIC The name of a resinous exudation obtained from incisions made in the bark of the Pistacia lentiscus growing in Chios and other islands of the Grecian Archipelago. It occurs in the form of small, yellow, translucent tears ; is soluble in alcohol, acetone, and turpentine, and is used among other applications for lacquer and varnish and as a chewing-gum. 310 MASTIC MATTER MASTIC (Continued) The same name mastic or gum mastic is employed to designate some forms of native bitumen. MATCHES See Phosphorus. MATLOCKITE An ore of lead (PbCl 2 ,PbO). MATTE (Mat) Impure copper sulphide in a fused state pre- pared in course of the production of metallic copper from its ore. By further roasting, it is converted into so-called " fine metal " or a purer sulphide, and by a repetition of the roasting in a current of air, the metallic copper is obtained by burning off the sulphur constituent. MATTER The substance of the chemical elements and their compounds of which the universe is composed, capable of assuming three distinct physical states namely, the fluid, solid, and gaseous. Water in its ordinary form, that of ice, and that of steam, is exemplary. Again, liquid mercury (quicksilver) can be frozen to a solid and vapourized by heat. The various kinds of matter are characterized by their properties. Matter is indestructible; only its forms can change. In a sense and that a very definite one all matter may be said to be alive, the liability to chemical change being the qualification for that description. Given the necessary environment, every known substance and compound is susceptible of change thus, for example, phosphorus, which is comparatively inert when kept under water, becomes very much alive when exposed to the air, and even more so when introduced into gaseous oxygen. This liability to change is shared by the substances of which living tissues are formed, and even the so-called death of living creatures does not constitute death even in a material sense. It is true that the microcosm the entity is changed, but the component parts are each and all alive individually, and are subject to further changes ac- cording to their environment. In some speculations, all the forms of matter are ascribed to simple differences in the arrangements and movements of the ultimate particles of positive and negative electricity, which in this view are the two primordial elements. The basic nature of primordial matter is as yet largely problematical. Whatever matter may be essentially, it is irrevocably bound up with force the one with the other * and probably both are comprehended and included in what we know as " chemical affinity." MATTERMENTHOL 311 MATTER (Continued) The mean density of the earth has been experimentally determined as 5*6747 times that of water. (See Elements, Electrons, and Radio-activity.) MAUVE The first aniline dye prepared in this country, being one of the so-called " safranines " group. It is a crystalline substance of green lustre which dyes mauve, but the colour fades in sunlight. It is used for colouring postage stamps, amongst other applications. MEASURES See Burettes, Pipettes, and Weights and Measures. MEERSCHAUM (SEPIOLITE or SEAFOAM) A very light deposit having a sp. gr. of o ( 8 to 1*0 found in certain alluvial deposits in Asia Minor, Greece, and elsewhere, consisting of a hydrated silicate of magnesium. It is, as a rule, slightly yellow in colour, and is used for making pipe-bowls and other articles. Talc and serpentine are other varieties of magnesium silicate. MELISSIC ACID (C3 H 60 O 2 ) One of the higher members of the fatty acids, with a melting-point of 90 C. MELITRIOSE (Mellitose) See Raffinose. MELLITIC ACID (C 12 H 6 O 12 ) Occurs in peat as so-called honeystone (mellite), or aluminium mellitate (C 12 Al 2 Oi 2 , i8H 2 O). When pure, it is a white, crystalline body, soluble in water and alcohol, of polybasic character, and can be obtained from lignite or graphite by oxidation with potassium permanganate. MENHADEN OIL See Fish Oils. MENISCUS The curved surface of a liquid confined in a tube due to capillarity, as witnessed in a solution contained in a burette or the column of mercury in a barometer. MENSTRUUM A solvent liquid used for extracting the soluble parts of a substance. MENTHENE (C 10 H 18 ) A terpene obtained from menthol by elimination of water. MENTHOL (Mint Camphor) (C 10 H 20 O) A colourless, crystal- line, camphoraceous substance which is deposited from peppermint oil when kept for a long time, or cooled to a low temperature, and large quantities of which are imported from Japan. It melts at 44*5 C., is soluble in alcohol and ether, and is nearly related to menthene (C 10 H 18 ), which can be obtained from it by elimination of water (as, for 312 MENTHOL MERCURY MENTHOL (Continued) example, by the action of phosphorus pentoxide). It is used medicinally, and in perfumery and confectionery. MENTHONE (C 10 H 18 O) is a ketone related .to menthol (C 10 H 20 O) and occurs with that substance as a constituent of oil of peppermint, and both it and menthol can be produced chemically from the oil of Eucalyptus dives. (See Thymol.) MERCAPTANS (Thio-Alcohols) A group of organic, liquid, inflammable compounds containing sulphur, analogous to the monohydric alcohols. They have a very sharp, un- pleasant odour, are insoluble in water but soluble in alcohol. Their relationship to alcohol is shown by the two illustrative formulae : thyl alcohol. C **f JS ethyl thio-alcohol They may be prepared by several methods as, for example, by heating alcohol with phosphorus pentasulphide, the oxygen being thus replaced by sulphur. MEBCERIZATION A treatment by which a silk-like lustre is given to cotton clothes or yarns as effected by the action of a 20 to 25 per cent, solution of caustic soda upon them while kept in a stretched condition so as to prevent shrink- ing of the fibres. The soda is subsequently washed out with water. The cotton fibre which is naturally a flattened hollow riband or tube swells up under this treatment by thickening into a cylinder with practically no hollow space, stronger than the unprepared cotton and more easily dyed. (See Silk, Artificial.) MERCURY (Hydrargyrum, Hg) and its Compounds Mercury (quicksilver) atomic weight, 200-6; sp. gr. at o C., 13*596; melting-point, z&'Sj C. occurs in nature to some extent in the free or globulous state admixed with its ores (par- ticularly the sulphide) of which cinnabar (HgS) is the best known. It is found in Austria, Italy, Mexico, Spain, California, China, Japan, etc. The world's production in 1913 was 4,200 tons. Mercury is made from the natural sulphide by roasting the ore, whereby the sulphur is burnt off as sulphur dioxide (SO 2 ), or by heating the ore mixed with lime in closed retorts. In this last-named process, the lime com- bines with the sulphur, whilst the mercury is liberated and distils over as vapour which condenses upon cooling into the well-known liquid form, MERCURY AND ITS COMPOUNDS 31.3 MEECUEY (Continued) Mercury is one of the chemical entities supposed to consist of isotopes, and their partial separation can be effected, as recently claimed, by evaporating the metal at low pressure and condensing the evaporated atoms on a cooled surface, the density of the condensed mercury being, it is stated, slightly lower than that of the residual metal. Apart from its uses in the construction of thermometers and barometers, it is largely used in making mirrors, amalgams, extraction of gold from its ores, in the manu- facture of vermilion, and in various electrical applications. It is a bright, silver-coloured, liquid metal which solidifies at about - 38-85 C. in a crystalline condition. It readily combines with many other metals, forming alloys or combinations which are called amalgams. Tin amalgams are used in making mirrors, while amalgams of tin and copper are used in dentistry as fillings or stoppings for teeth. (See Amalgams. ) Oxides of Mercury When submitted to long heating in the air above 300 C., the metal is slowly converted into the red mercuric oxide (HgO), whereas when this oxide is heated to redness it is again decomposed into its constituent elements. The red oxide is used as a pigment and for making anti-fouling marine paints. Mercury forms several other combinations with oxygen. The salts of mercury corresponding to the lower or mercurous oxide (Hg 2 O) are styled " mercurous," and those corresponding to the higher (mercuric) oxide (HgO) are classified as " mercuric " compounds. The lower oxide is precipitated in a dark brown form in hydrated state when an alkali is added to a mercurous salt in solution. Mercurous Chloride (Hg 2 Cl 2 ) (calomel) is a white, crystal- line body, insoluble in water, used in medicine. Mercuric Chloride (HgCl 2 ), or corrosive sublimate, as it is also known, is a white, crystalline substance, soluble in water, and is possessed of poisonous and very powerful antiseptic and germicidal properties, for which reason it is used by taxidermists in preparing the skins of animals, also by surgeons (in very dilute solution) as an antiseptic wash. Mercuric Sulphate (HgSOJ is a white, crystalline sub- stance, insoluble in water, used in the preparation of the two chlorides and in the extraction of gold and silver from roasted pyrites. Mercuric Iodide (HgI 2 ) is insoluble in water and is di- 314 MERCURYMETALS MERCURY (Continued) msorphous ; when heated to 150 C. the scarlet crystals are changed into another and yellow crystalline form, but which upon being lightly touched is at once retransformed into the original state. Mercuric Nitrate (Hg(NO 3 ) 2 2H 2 O) is a crystalline, soluble salt, of deliquescent character, used in medicine and felt manufacture. Mercuric Sulphide (HgS), as obtained by the precipitation of a mercuric salt with hydrogen sulphide, is black and in- soluble ; but when washed, dried, and sublimated, it becomes red, forming the so-called " vermilion," in which form it is manufactured for use as a pigment and for colouring sealing- wax (red). Mercuric Cyanide (Hg(CN) 2 ) is colourless, crystalline, and soluble in water. It is used for making cyanogen gas and in photography. Mercury Fulminate See Fulminating Mercury. All the mercury compounds are poisonous. MET A -COMPOUNDS Substitution products derived from benzene in which the substitutory radicals or groups are constitutionally placed in certain definite positions in the nucleus meta-cresol, for instance. META-CRESOL See Cresol. METALS The metallic elements as a class are capable of taking a high polish, but some, of course, more than others. Gold, copper, and platinum, for example, may be polished and burnished to a very high degree much more than iron, lead, and arsenic. Again, some are much more ductile than others, and can therefore be easily drawn out into wire. For example, copper in this form is largely used for telegraphic purposes. Others are of a malleable character that is to say, can be easily beaten into any desired shape with a hammer or mallet lead, for example. Gold and several other metals can be hammered into extremely thin sheets gold leaf, for example. (See p. 234.) Most metals are good conductors of heat, sound, and electricity. At a temperature approaching absolute zero, pure metals lose practically all electrical resistance and become nearly perfect conductors. There are great differences between the hardness, brittle- ness, weight, tensile strength, and other properties of the various metals. METALS METALLIC ORGANIC COMPOUNDS 315 METALS (Continued) The following table comparing the production within the Empire with the estimated normal consumption apart from special war demands is taken from a recent British Official Report : Production. Consumption. Tons. Tons. Iron ... ... 4,600,000 7,000,000 Tin ... ... 5,100 21,000 Lead ... ... 17,000 179,000 Zinc ... ... 4,800 185,000 Copper ... ... 140 130,000 Manganese (ore) ... 4,500 400,000 Wolfram... ... 260 4,000 The individual metals and their characters are described under their respective names. (See also Alloys.) TABLE OF MELTING OR FUSING POINTS OF SOME IMPORTANT METALS AND THEIR SPECIFIC GRAVITIES. Aluminium ... ... 6587 C. 2-58 Antimony ... ... ... 630 C. 6-7 Bismuth ... ... ... 271 C. 9-823 Cadmium ... ... ... 320-9 C. 8-642 Chromium... ... ... 1,615 C. 6-92 Copper ... ... ... i,o83C. 8-95 Wrought Iron ... ... 1,600 C. 7*80 Lead ... ... ... 327-4 C. 11-3 Manganese ... ... 1,230 C. 8-0 Silver ... ... ... 960-5 C. 10-5 Tin ... ... ... 231-9 C. 7-2 Zinc ... ... ... 419*4 C. 6*9 Platinum ... * ... ... 1,775 C. 21 '5 Steel ... about 1,350 to 1,375 C- about 7-60 to 7-80 METALLIC CARBONYLS Compounds of metals with carbon monoxide, the nickel compound being NifCO)^. (See Nickel.) An iron compound a pale yellow, viscid liquid (Fe(CO)g) is also known. METALLIC ORGANIC COMPOUNDS These include mercury phenyl (Hg(C 6 H 6 ) 2 ), which is obtained by the action of sodium amalgam on bromo-benzene ; tin, lead, and magnesium form corresponding compounds. Other organo- metallic compounds are described under the respective metals, arsenic, antimony, boron, silicon, platinum, etc. 316 METALLIC NITROXYLS METHYL CHLORIDE METALLIC NITROXYLS Combinations of metals with nitric peroxide, such as copper nitroxyl (Cu 2 NO 2 ), formed by the action of nitric peroxide on metallic (reduced) copper. METALLOID A term sometimes given to those elements such as arsenic and selenium which are not decidedly metallic, but appear to occupy a position on the borderland between the absolutely metallic and non-metallic elements. METALLURGY The art of extracting and working in metals. METAMERIC Substances which have the same molecular weights and identical percentage composition, but are of different types and structure and furnish different products by chemical changes, such as acetone (CO(CH 3 ) 2 ) and allyl alcohol (C 8 H B (HO)). METAMORPHISM The changes in minerals (rocks) of chemical and physical characters. METEORITES Mineral substances of meteoric origin which have fallen on the earth's surface some of iron or iron alloyed with nickel ; many others are composed of silicates or of the various elements entering into the composition of terrestrial minerals. Most of them are fused on their sur- faces, doubtless brought about by their rapid passage through the atmosphere. METHANE See Hydrocarbons and Marsh Gas. METHYL ACETATE (CH 3 CO 2 .CH 8 ) A colourless, fragrant, volatile liquid, of sp. gr. 0-9244 and boiling-point 54 C. ; soluble in water, alcohol, and ether; made by heating methyl alcohol and acetic acid in presence of sulphuric acid and distilling. It is used as a solvent, in perfumery, and making extracts. METHYL ALCOHOL See Alcohols. METHYL BENZOATE (Essence Niobe) (C 6 H 5 .CO 2 .CH 3 ) A colourless solution ofsp.gr. 1-09 and boiling-point i98-6C.; soluble in water and alcohol, used in perfumery, and pre- pared by heating benzoic acid and methyl alcohol in the presence of sulphuric acid. METHYL BLUE See Aniline and Dimethylaniline. METHYL CHLORIDE (Chloromethane) (CH 3 C1) is a colourless gas of ethereal odour, used in medicine and for refrigera- tion, prepared by the action of hydrochloric acid on methyl alcohol in the presence of sulphuric acid. It boils at 27-7 C. and is soluble in water and alcohol. METHYL CINNAMATE"METOL" 317 METHYL CINNAMATE (C 6 H 6 CH.CHC9 2 .CH 3 ) (prepared from cinnamic acid and methyl alcohol in the presence of sulphuric acid, followed by distillation) is a colourless, crystalline substance, of melting-point 36 C., boiling- point 259*6 C. ; soluble in alcohol and ether, and used for flavouring and in making perfumery. METHYL ETHEE See Ethers. METHYL IODIDE (CH 3 I) A liquid halogen derivate, soluble in alcohol. METHYL SALICYLATE (C 6 H 4 (OH)COO,CH 3 ) The prin- cipal constituent of oil of wintergreen. A colourless liquid of sp. gr. 1-185 an d boiling-point 222-2 C., soluble in alcohol and ether. Chemically, it is the methyl ester of salicylic acid. The artificial oil of wintergreen is prepared by heating a mixture of methyl alcohol and salicylic acid in presence of sulphuric acid. It is used in medicine, and for flavouring purposes. (See Oil of Wintergreen.) METHYL SULPHONAL An organic body of complicated con- stitution known under the trade name of "Trional," and used as an hypnotic. METHYL VIOLET A synthetic dye. (See Aniline.) METHYLAMINE See Amines. METHYLATED SPIRIT A mixture of alcohol with 10 per cent, of common wood-spirit, tainted (denatured) with other substances, such as paraffin oil, to render it unfit for con- sumption, but available for chemical and manufacturing purposes, as an alcoholic solvent and fuel. METHYLENE (CH 2 ) The hypothetical first member of the olefine series of hydrocarbons, but which, so far as is known, does not exist. The dichloride (CH 2 C1 2 ) is a volatile liquid used as a local anaesthetic. METHYLENE BLUE, or Tetramethyl-Thionate Hydrochloride (C 16 H 18 N 3 SC1), is used as a bacteriological stain; also in medicine and in dyeing cotton yarns. METHYLENE CHLORIDE, or Dichloromethane (CH 2 C1 2 ), is a colourless, volatile liquid of sp. gr. 1-2615 and boiling-point 42 C., soluble in alcohol and ether, used as a local anaes- thetic, and prepared by the chlorination of methyl chloride, followed by distillation. "METOL" A cresol derivative used as a photographic developer. 3 i8 METREMILK OF SULPHUR METRE See Weights and Measures. METRIC SYSTEM See Weights and Measures. MICA The somewhat general name of a number of minerals, including Muscovite, having a more or less laminated or so- called micaceous character. For the most part, they are hydrous silicates of magnesium and potassium, but they are of varying and complicated composition. Considerable sup- plies come from India and the Argentine, where there is a growing industry in the material. The uses of mica in the arts are similar to those of talc. MICROBES, or MICRO-ORGANISMS, are extremely minute living organisms by whose agency the processes of decay, putrefaction, many fermentations, and other chemical changes are brought about. Some of them play an important part in connection with infectious diseases and they are roughly divided into two classes viz. , aerobes, which require oxygen for their sustenance, and anaerobes, which cannot live in oxygen, and are killed by exposure thereto. The function of anaerobes would appear to be largely in the nature of hydrolysis (see Hydrolysis), and that of aerobes one of oxidation. (See also Bacteria, Nitrification, and Sewage.) MICROCOSMIC SALT A compound phosphate of hydrogen sodium and ammonium (Na(NH 4 )HPO 4 ,4H 2 O) obtained by mixing solutions of ordinary sodium phosphate and ammo- nium chloride. MICROSCOPE An instrument so constructed as to magnify the objects looked at through it. When it has only one lens it is termed a simple microscope, but when fitted with two or more it is known as a compound microscope. MILE The sole natural food of all the mammalia for some time after birth. It contains water, fat, proteid substances, milk-sugar, and certain salts, the relative proportions vary- ing with the species. Cow's milk has a sp. gr. of about i '03, contains about 14 per cent, of solids, of which about 4 per cent, is fat, and gives about 0*8 per cent, of ash. In souring, the milk-sugar is converted into lactic acid. The so-called " condensed milk " is made by evaporating off a quantity of its water to about one quarter of its original bulk sugar being generally added at the same time. It keeps well, but as it is generally made from skimmed milk it is not so nourishing as fresh milk. MILK OF SULPHUR See Sulphur. MILK-SUGAR MIRBANE (OIL OF) 319 MILK-SUGAR See Lactose. MILLON'S TEST, for albuminoids in suspected tissues, consists in moistening with a solution of 2 parts mercury dissolved in 4 of nitric acid of sp. gr. 1-40, and gently warming, when an intense red colour is produced if albuminoid matter be present ; this colour is not destroyed by boiling with water or exposure to the air. "MILTON" A proprietary disinfectant liquid containing sodium hypochlorite as its active agent. MIMOSA BARK The produce of the Acacia mimosa, containing an astringent principle used in tanning and resembling cutch in character and composition. (See Cutch.) MINERALS Rocks and other inorganic materials found naturally. The output of minerals from all sources in the United Kingdom in 1919, as reported by the Chief Inspector of Mines, was as follows : Mineral. Total Output. Mineral. Total Output. Tons. Tons. Alum shale 4,848 Iron ore 12,254,195 Arsenic 2,527 Iron pyrites 7,336 Arsenical pyrites 75 Lead ore 13,868 Barium compounds ... 60,087 Limestone (other than 9,537,495 Bauxite 9,221 chalk) Bog ore 3,045 Manganese ore 12,078 Chalk 2,629,406 Cubic Feet. Cheet, flint, etc. 50,082 Natural gas 90,000 Chromite of iron . . 3C 5 Tons. Clays and shale (in- 7,765,965 Ochre, umber, etc. ... io,547 cluding china clay, Oil shale 2,763,875 china stone, and Rock salt 90,938 mica clay) Salt from brine 1,817,142 Coal ... 229,779,517 Sandstone 1,699,853 Copper ore and pre- 372 Slate 164,098 cipitate Soapstone 688 Fluorspar 36,860 Strontium sulphate ... 1,872 Gravel and sand 2,048,427 Tin ore (dressed) 5, J 56 Gypsum 220,003 Tungsten ores 166 Igneous rocks 4,387,703 Zinc ore 6,933 MINERAL OILS See Petroleum. MINIUM (Bed-Lead) See Lead. MIRBANE (OIL or ESSENCE OF) A trade name for nitro- benzene as used in perfumery. (See Nitro-benzene.) 320 MISCIBILITY MOLECULES MISCIBILITY Capability of admixture to a state of perfection. For example, vinegar can be admixed with water in all proportions, and oil of turpentine is miscible with spirits of wine. Miscibility is a property of gases also : oxygen gas can be mixed with hydrogen, for example ; but solid bodies are not miscible in the same chemical sense. (See Mixtures and Diffusion.) MISPICKEL Arsenical pyrites (FeS 2 + FeAs,,). (See Arsenic.) MIXTURE This term is not identical in meaning with com- pound in the chemical sense. A mixture of lead shots and powdered sulphur can be made, but it is neither uniform nor a compound, as the lead shots can be picked out one by one. Similarly, iron-filings can be mixed with sand, but the iron- filings can be abstracted from the mixture by means of a magnet. (See Chemical Compounds and Diffusion.) " MOLASOCABB " A decolourant black made by decomposing molasses with lime, burning the mixture, and subsequently washing the char with chemicals to remove the lime salts. MOLASSES (Treacle) Uncrystallizable drainings from cane sugar, used to some extent for making glycerine. It is used for sweetening purposes and in the preparation of rum by fermentation and subsequent distillation of the fer- mented product. A low-grade cane molasses is known as " blackstrap." (See Glycerine and Sugar.) MOLECULES AND MOLEOULAE WEIGHTS The term mole- cules in a chemical sense, means the smallest quantities of substances capable of existing in the free (uncombined) state, as contrasted with atoms, which are regarded as constituents of molecules and the smallest parts of matter which can par- ticipate in any chemical change. For instance, a molecule of sodium chloride (NaCl) (common salt) is a combination of an atom of the metal sodium (Na) with one atom of the gas chlorine (Cl) Na + Cl=NaCl and as the atomic weight of sodium is 23 and that of chlorine 35*5, it follows that the molecular weight of the compound is 58*5. Again, in the production of water (H 2 O), 2 atoms of hydrogen (H) combine with i atom of oxygen (O) to form a molecule of water (H 2 O) H0 and when water is decomposed by electrolysis, its mole- cule yields 2 volumes of hydrogen gas and i volume of oxygen gas at the same temperature and pressure. MOLECULES AND MOLECULAR WEIGHTS 321 MOLECULES AND MOLECULAR WEIGHTS (Continued) It is generally assumed (although it cannot be re- garded as absolutely proven) that equal volumes of gases, at the same temperature and pressure, contain the same number of molecules, this assumption, which harmonizes with so many known chemical facts, being known as Avogadro's law. If, then, equal given volumes of hydrogen and oxygen contain severally i molecule it follows that as oxygen is known to be 16 times heavier than hydrogen, which has an atomic weight of i, and as the molecule of hydrogen consists of 2 atoms, the molecular weight of oxygen must be 16x2 = 32. To take another instance, hydrochloric acid is a com- bination of i atom hydrogen gas with i atom of chlorine* H + C1 = HC1 and the respective weights of equal volumes of hydrogen and hydrochloric acid gases are i and 18-25. As the weight of hydrogen contained in a molecule of hydrochloric acid is only one-half that of the same element contained in an equal measure or volume of hydrogen, and as there is only i atom of hydrogen in the molecule HC1, it necessarily follows that the molecule of hydrogen consists of 2 atoms, and that the molecule of HC1 must weigh 36-5, made up of Name of Element. Atomic Symbol. Atomic Weight. Molecular Weight. Molecular Symbol. Vapour Density. Hydrogen Nitrogen H N I H 2 28 H 2 N 2 I H Oxygen O 16 32 2 16 Ozone O 16 4 8 3 24 Fluorine F I 9 38 F a 19 Sodium Na 2 3 23 Na "'5 Phosphorus ... P 3i 124 P 4 62 Chlorine Cl 35'5 7 1 C1 2 35'5 Potassium . . . K 39 39 K !9'5 Zinc Zn 65 65 Zn 32-5 Arsenic As 75 300 As 4 !50 Bromine .... Br 80 1 60 Br 2 80 Iodine I 127 254 I 2 127 Mercury Hg 200 200 Hg 100 21 322 MOLECULES AND MOLECULAR WEIGHTS MOLECULES AND MOLECULAR WEIGHTS (Continued) i atom of H weighing i and i .atom of chlorine weighing 35*5. The molecular weight of chlorine is therefore 71. The relative weights of equal volumes of gases at the same temperature and pressure are known as their vapour densities, and it will be seen from the table on p. 321 that these are one-half of the numbers representing their mole- cular weights. In other words, the atomic weights of gases are, with some exceptions, half the/weights of the volumes of them respect- ively, equal to the volume of a molecule of hydrogen gas at the same temperature and pressure. In those instances where the vapour densities are identical with the atomic weights, the molecules of the elements con- sist of 2 atoms, while the molecules of sodium, potassium, zinc, and mercury consist of i atom, and therefore their atomic and molecular weights are identical. Phosphorus and arsenic contain 4 atoms to each molecule, or in other words, the smallest weight of these substances which can take part in any chemical change is a fourth of their molecular weight or one-half of their vapour densities. (See Vapour Densities.) The molecular weights of organic compounds are ascer- tained by determining the composition of their several combinations, as the mere analysis of them only gives the relative proportions of their ingredients. For example, the analysis of acetic acid shows that it contains 40 per cent, carbon, 6*6 per cent, hydrogen, and 53-4 per cent, oxygen, and if these percentages are divided by the atomic weights of the several constituent elements it will be found that their relative proportions are 3-3, 6-6, and 3-3, so that the formula 5 might be either CH 2 O, C 2 H 4 O 2 , or C 3 H 6 O 3 ,etc. The analysis, however, of silver acetate shows that i atom of hydrogen is replaced by i of silver, so that the formula of this salt is C 2 H 3 AgO 2 (or Ag,C 2 H 3 O 2 ), and that of acetic acid C 2 H 4 O 2 . As regards volatile organic substances, much assistance is rendered by ascertaining the densities of their vapours, as every molecule occupies a volume twice as large as that of an atom of hydrogen. There are a number of other contributory methods too technical to be described in this volume but which may be lightly referred to here. The " cryoscopic " method depends upon the ascertained fact that in certain chemically allied cases, the freezing-points of solutions are depressed pro- portionately to the number of molecules of the substances dissolved in equal volumes of the same solvents. The boiling- point method depends, on the other hand, upon the considera- tion that the boiling-points are raised from the same cause. MOLYBDATESMONAZITE SAND 323 MOLYBDATES Compounds formed by the action of bases such as the alkalies on molybdenum trioxide. MOLYBDENITE See Molybdenum. MOLYBDENUM (Mo) Atomic weight, 96 ; sp. gr., 8-56 ; and melting-point, 2,550 C. Molybdenum is contained in the mineral called molybdenite, which is a sulphide (MoS 2 ) of the metal (resembling graphite in appearance) found in Bohemia, Canada, and Sweden. It also occurs in molyb- denum ochre, which is an oxide of the metal (MoO 3 ); wulfenite, a double oxide of lead and molybdenum (PbMoO 4 ); and molybdite (Fe 2 O 3 ,3MoO 3 ,7|H 2 O), which often accompanies molybdenite. Upon roasting the native sulphide in a current of air, the sulphur is burnt off as sulphur dioxide (SO 2 ), an oxide of molybdenum being left behind, and by mixing this with oil and charcoal and then strongly heating the mixture, the molybdenum is reduced to the metallic state. The metal is also prepared by alumino-thermic reduction of molybdic acid (H 2 MoO 4 ), which can be readily prepared from the trioxide. The metal is greyish-white, brittle, and difficult to fuse. It is used in place of tungsten to the extent of about i per cent, in making high-speed steel parts, such as crankshafts and connecting-rods, and otherwise in metallurgy. When heated in the air, it oxidizes into a yellow powder, having the composition represented by MoO 3 , and several chlorides of molybdenum are known. MONAZITE SAND A natural crystalline phosphate of cerium and lanthanum generally containing thorium compounds also, which occurs naturally in extensive deposits in Colorado and Carolina, the coast of Brazil, and Travancore (a native Indian state under British protection). The latter deposit was discovered in 1900, and in September, 1914, certain rights were obtained on behalf of a British com- pany, with the result that Germany has now lost its former dominion over the gas-mantle market. These native deposits of sand are freed from much of the associated lighter materials by sluicing with water and electro-magnetic separation, so that the purified product consists of from 85 to 90 per cent, real monazite, containing about 9 per cent, thoria and 60 per cent, of cerium oxides. These in turn are subsequently converted into nitrates, in which form they are marketed for use in the incandescent mantle trade. Brazilian monazite contains about 6 per cent, thorium 324 MONAZITE SAND MOSS AGATE MONAZITE SAND (Continued) oxide, the Travancore and Ceylon deposits about 9 per cent., and while some are reported to contain as much as 18 per cent., other varieties are devoid of this constituent. (See Gas Mantles and Thorium.) MOND GAS See Producer Gas. " MONEL " A proprietary alloy, consisting of approximately 67 per cent, nickel, 28 per cent, copper, and 5 per cent, other metals ; sp. gr., 8'82, and melting-point, 1,360 C. It is of great tensile strength and high resistance to many corroding agencies ; used for making superheated steam fittings and parts of chemical plant used under caustic alkaline conditions, etc. MONTAN or MONTANA WAX When purified by distillation with superheated steam is a white bituminous substance soluble in carbon tetrachloride, benzol, and chloroform ; extracted from the lignites of Saxony and Thuringia, melting at about from 80 to 90 C., and used in candle-making and as a substitute for carnauba wax, etc. (See Lignite and Waxes.) MOONSTONE Transparent felspar. MORDANTS Chemical substances used for fixing colours in dyeing and calico printing, the colouring matter being thereby securely attached to the fibres of the material in the form of coagulated or precipitated compounds known as " lakes." (See Dyes and Lakes.) MORPHINE (C 17 H 19 NO 3 ,H 2 O) Many of its salts, including the acetate, hydrochloride, nitrate, and sulphate, which are all soluble in water, are used in medicine. (See Opium.) MORTAR A mixture of burnt lime slaked with water to a thin cream, and sharp sand, the hardening and setting of which (as when used for joining bricks together) depends partly upon drying and partly upon absorption of carbon dioxide from the air by the lime, thus converting it into calcium carbonate CaH 2 O 2 + CO 2 = CaCO 3 + H 2 O. It contains about 73 '4 per cent, sand and 6*5 per cent. CaO. MORUS TINCTORIA See Fustic. MOSAIC GOLD An alloy of copper and zinc in equal parts, also used as the name of a pigment made of the golden- yellow-coloured stannic sulphide (SnS 2 ). MOSS AGATE A variety of the mineral known as chalcedony. MOTHER-LIQUORMURIATIC ACID 325 MOTHER-LIQUOR The residual liquor after the chief con- stituent substance has been removed from it as far as possible by deposition or crystallization. For example, codeine being a more soluble substance than morphine, is contained in the mother-liquor after the morphine has crystallized out. Bromine is recovered from the mother- liquor left from the manufacture of potassium chloride. (See Bromine.) MOTHER OF PEARL The brilliant, silvery, hard layer of oyster and other shells. MOTOR GREASE is prepared in a number of varieties, ordinary soap being used in many. One recipe is as follows : Lubricating oil of sp. gr. 0-900 to 0-910, 80 parts; stearic acid, 15 parts; and caustic soda, 2 parts, part of the oil being melted with the stearic acid and mixed with the soda in 40 per cent, solution, and the remainder of the oil being subsequently incorporated. Cheaper grades are compounded with lime soaps. MOTOR SPIRIT See Gasoline and Petrol. MOTTRAMITE See Vanadium. MOURA (MOWRA) OIL A yellow, semi-liquid fat, soluble in ether, benzene, and carbon disulphide, of sp. gr. 0-894 to 0-898, extracted from the seeds of Bassia latifolia (India), has an odour like that of cacao beans, and is used in soap- making. MUCIC ACID (C 6 H 10 O 8 ) A crystalline, dibasic acid prepared by oxidation of dulcitol, gums, mucilage, etc., sparingly soluble in cold water ; melting-point, 213 C. MUCILAGE Gum prepared from seeds and roots which contain large quantities of a substance which swells up with water into a mucilage. Such mucilages can be pre- pared from linseed and quince seed, but the term now is generally applied to any kind of adhesive paste. (See Adhesives.) MUNDIC A Cornish name for iron pyrites. MUNTZ METAL See Copper. MUREXIDE (Ammonium Purpurate) (NH 4 )CgH 4 N 5 O ) A purple colouring matter produced from uric acid by moisten- ing with nitric acid and gently warming with ammonia. Its production is a test for the presence of uric acid. MURIATIC ACID An old name for hydrochloric acid. (See Chlorine.) 326 MUSCARINE MYRRH MUSCARINE (C 5 H 15 NO 3 ) A very poisonous base contained in toadstool (Agaricus muscarius), which can also be produced from choline by oxidation with strong nitric acid. Choline is found present in brain matter and in the bile. (See Neurine.) MUSCOVITE Common mica (Al 2 O 3 .SiO 2 +K 2 O.SiO 2 ). MUSK An aromatic, resinous substance used in perfumery, obtained from an internal part the preputial follicles of the musk deer (Moschus moschiferus) inhabiting Tonquin and Thibet. The odour is due to a ketone named muskine (C 15 H 28 0). MUSK (Artificial) A nitro-aromatic compound (C U H 13 N 3 O 6 ). MUST The juice of crushed grapes as expressed for wine- making. MUSTARD A condiment made from the seeds of black and white mustard (Sinapis nigra and 5. alba) by grinding and sifting. Both of them yield oil by pressure to the extent of 36 per cent, in the case of the white seed and about 1 8 per cent, in the case of the black variety. This oil has a sp. gr. of 1-014 to i -103 and a refractive index of I'S^S to I *535* I* contains some allyl compounds and is used in medicine. In addition to this fixed oil, the seeds of the black variety, after pressure, contain a glucoside named sinigrine, which by the action of an enzyme named my rosin yields, upon moistening with water and standing, a very pungent volatile oil containing sulphur (allyl isosulpho- cyanate), together with glucose. The white mustard seeds contain an alkaloidal body named sinapine. MUSTARD GAS See Gassing. MYELINES Complicated substances containing phosphorus, which are obtained from brain matter ; they are of crystal- line character, and soluble in hot alcohol. MYRABOLANS The dried fruit of the Chinese and Indian trees Myrabolanus chebula, which contain about 30 per cent, tannin and are used in the tanning industry. MYRCIA OIL See Bay Oil. MYRISTIC ACID (C 14 H 28 O 2 ) A crystalline fatty acid of the normal series, present in oil of iris and nutmeg-butter, obtained from Myristica moschata. It has a melting-point of 54 C. and is soluble in hot alcohol. MYRISTICIN See Nutmeg Oil. MYRRH A resinous gum which exudes from the Balsamoden- dron myrrha (grown in Arabia, Abyssinia, and Somaliland), MYRRH NAPHTHALENE 327 MYRRH (Continued) associated with a volatile oil in common with other similar exudations from terebinthaceous shrubs. Tincture of myrrh is mildly disinfectant, and is used as a local stimu- lant to mucous membranes. Myrrh is also used as a con- stituent of tooth-powder. An oil is distilled from the gum known as myrrh oil, which has a sp. gr. of 0*988 to 1*007, ^ s soluble in alcohol and ether, and used in perfumery. MYRTLE OIL distilled from the leaves of Myvtus communis is light yellow and of agreeable odour, containing cineol, dextropinene, and dipentene. It is soluble in alcohol and ether, has a sp. gr. 0-89 to 0*92, and rotation + ioto +30, and is used in medicine. MYRTLE or LAUREL WAX A crystalline hydrated glyceride obtained from the berries of various species of Myrica. NAPHTHA A more or less general term given to oily bodies produced in the distillation of cannel-coal and bitu- minous shale, containing paraffin in solution of mixed hydro- carbons. These are used for illuminating purposes, also as solvents. One such liquid is found associated with deposits of bitumen and asphalt in many places and is distilled therefrom. Heavy Naphtha is dark-coloured as prepared from coal tar, has a sp. gr. of 0-925 to 0-950 and flash-point about 78*3 C. It is used as a solvent and in paint-making. Water- white Naphtha has a sp. gr. of 0-870 to 0-880, a flash-point not below 37'8 C., and is largely used as a solvent. Solvent Naphtha is a mixture of benzol, toluol, xylol, etc., derived from coal tar distillation. (See Coal and Petroleum.) NAPHTHALENE (C 10 H 8 ) A solid hydrocarbon obtained from coal tar and chiefly contained in the fraction that distils between 180 and 200 C., from which it crystallizes out on cooling and is subsequently purified by treatment with small quantities of strong sulphuric acid, followed by sublimation. Pure naphthalene crystallizes in white glistening plates, melts at 80 C., boils at 218 C., and is readily soluble in hot alcohol, benzol, and ether. It has a peculiar tarry odour, and is prepared commercially in the forms of crystals, flakes, balls, powders, and sticks. It is largely used in the manufacture of artificial indigo and dyes, also for the 328 NAPHTHALENE "NARKI" METAL NAPHTHALENE (Continued) carburation of illuminating coal gas. It possesses anti- septic properties and is carried in the forms of balls and sticks by the natives of India and the Far East as a fever preventive. It is also employed therapeutically, and has been advocated as a motor fuel in a state of solution in benzol. Mononitro -Naphthalene (C 10 H 7 NO 2 ) is used in the pre- paration of explosives and dyes. Dinitro-Naphthalene (C 10 H 6 (NO 2 ) 2 ) is used in the pre- paration of explosives and "alizarin black." NAPHTHENES Constituents of Russian petroleum to the extent of almost 80 per cent. They are hydrocarbons of the general formula C W H 2M , such as cyclopentane (C 5 H 10 ) and cyclohexane (C 6 H ]2 ) (isomeric with the olefmes). The American oil consists for the most part of paraffin hydrocarbons. (See Hydrocarbons and Petroleum.) NAPHTHOL (Alpha) (C 10 H 17 OH) is a colourless, crystalline substance which melts at 94-2 C. and is soluble in benzol, alcohol,, and ether, but only slightly soluble in water. It is prepared by fusing alpha-naphthalene sulphonate and caustic soda, decomposing subsequently with hydrochloric acid and distilling. It is used in making dyestuffs. NAPHTHOL (Beta) (C 10 H 17 OH) is a white, lustrous substance, soluble in benzol, alcohol, ether, and chloroform, and slightly soluble in water, made by fusing beta-naphthalene sulphonate with caustic soda and subsequent distillation. It is used in making dyestuffs and as an antiseptic. NAPHTHYLAMINES are so-called "intermediates" for dyes, and include 0-naphthylamine (C 10 H 7 NH 2 ), a colourless, crystal- line compound of disagreeable odour, which melts at 50 C., boils at 300 C., and is readily soluble in alcohol ; and i-naphthylamine is also a crystalline compound which melts at 112 C., boils at 294C., and is odourless. NARCEINE See Opium. NARCOTINE (C 22 H 23 NO 7 ) (melting-point, 176 C.) A crystal- line alkaloid found present in opium to the extent of from about 2j to 10 per cent. It is a powerful narcotic poison, acting like morphine on the sensory cells, although less de- cidedly, and it is not so poisonous. (See Opium.) "NARKI" METAL A proprietary acid-resisting silicon cast iron alloy used in making plant for concentration of sul- phuric acid, acid elevators, pipes, valves, etc. NA SCENT NEPHRITE 329 NASCENT A term used to indicate the state of chemical sub- stances at the moment of their generation or formation, when they are often more active in their properties than ordinarily. Certain experiments have been recently made which show that the chemical affinity of such gases as hydrogen, oxygen, nitrogen, or carbon monoxide is in- creased by bringing them in contact with solutions in very minute bubbles, as obtained, for example, by forcing these gases through cartridges of paper. Hydrogen was thus proved to reduce mercuric chloride to calomel, potassium nitrate to nitrite, and carbon dioxide to formaldehyde. With oxygen gas, ammonia was oxidized to nitrous acid and methyl alcohol to formaldehyde ; while with nitrogen and hydrogen an indication of the production of ammonia was observed. NATROLITE A crystalline zeolite mineral (Na 2 Al 2 Si 3 O 10 , 2H 2 O). (See Zeolites.) NATRON A crude native form of sodium carbonate found in the soda-lakes of Egypt, Hungary, Magadi, and elsewhere. (See Sodium.) NEAT'S-FOOT OIL A liquid oil, soluble in alcohol and ether, obtained in the process of boiling down calves' and sheep's feet. Sp. gr., 0*964 to 0-98 ; saponincation value, 70 to 75; iodine value, 191 to 199 ; and refractive index, 1*469. It is used as a leather dressing and lubricant. NECTAR A sugary juice which collects in the nectaries or discs of flowers, containing cane sugar together with uncrystallizable sugar. NEODYMIUM (Nd) Atomic weight, 144-3 5 S P- g r -> 6-9563. An extremely rare, recently discovered element belonging to the cerium group, which has been isolated by the electrolysis of its anhydrous chloride. It has a melting- point of 840 C. and forms salts of a rosy colour. An oxide (Nd 2 O 3 ) of a pale blue colour is known. The hydroxide (Nd(OH) 3 ) is obtained by adding alkali to a solution of its salts; and the chloride (NdCl 3 ), nitrate, bromide, and iodide, are crystalline soluble salts. NEON (Ne) Atomic weight, 20*2. An element present in the air to the estimated extent of only i part in about 100,000. It exhibits a characteristic spectrum and has been liquefied. It is a member of the argon group, more volatile than argon, and exhibits no decided chemical characteristics. NEPHRITE A mineral something akin to jade. (See Jade.) 330 NEROL NICKEL NEROL (C 10 H 18 O) An aromatic alcohol of sp. gr. 0-881 isomeric with geraniol, occurring in the finer extracts of rose and neroli. NEROLI OIL A reddish -yellow essential oil distilled from orange flowers, of which there are several varieties (Citrus aurantium vulgaris, etc.). Sp. gr. about 0-87 to 0-88, soluble in alcohol, ether, etc. Its constituents include linalyl acetate, linalool, geraniol, and limonene. (See Linalool.) NESSLER'S REAGENT A solution of mercuric iodide in potassium iodide made alkaline by potassium hydrate, which turns yellowish-brown even with traces of ammonia, for which it is a delicate test. NEURINE (C 5 H 13 NO or C 5 H 15 NO 2 ) An amine base obtained from brain-substance and bile, and which upon oxidation with strong nitric acid gives muscarine (C 5 H 15 NO 3 ). It is nearly related to choline. NEUTRALIZATION The removal of acidity or alkalinity from a solution to a neutral state by. means of an alkaline or acid solution, as tested by litmus-paper. NICKEL (Ni) and its Compounds Atomic weight, 59 ; sp. gr., 8'8 ; melting-point, 1,452 C. Nickel occurs in com- bination in a number of minerals (chiefly in combination with arsenic) as kupfernickel (Ni 2 As 2 ), white nickel (NiAs 2 ), nickel glance (Ni 2 (AsS) 2 ), and nickel blende (NiS) ; also in association with cobalt in speiss. Nickel deposits have recently been found at Blaaubank and in the Pelandsberg (Rustenberg) district of South Africa. It can be obtained by heating the oxalate of nickel out of contact with air, or by reduction of the oxide with carbon at a high temperature ; but is now made commer- cially in large quantity both from the sulphide ores and the mineral garnierite a silicate of nickel and magnesium found in New Caledonia and Oregon (and which is first of all converted into sulphide) by a roasting process, in which the sulphur and arsenic constituents are for the most part burned off, the resulting mixed metallic oxides being sub- sequently heated to from 50 to 80 C. in a stream of so- called "producer gas " containing carbon monoxide. (See Producer Gas.) By this process they are reduced to the metallic state, other than the nickel ; this enters into combination with the carbon oxide, forming nickel carbonyl (Ni(CO) 4 ), which passes off in a vaporous state; and from this, the nickel is obtained by passage of the gases through a pipe heated to about 180 C., whereby the NICKEL NICOTINE 331 NICKEL (Continued) mixture is resolved into gaseous carbon oxide (which is used over again in fresh operations), the free metallic nickel being deposited in a lustrous mirror-like form. There is also an electrolytic process of preparing nickel in the forn\of cathode sheets, from the roasted ore after leaching with acid to remove most of the copper. In the free elemental state, it is best known as a black powder, but it can be obtained in the metallic state and is then a bright, lustrous, white, ductile, malleable but tenacious metal of very hard character and high melting-point. It is used chiefly, amongst other applications, for toughening steel and in the manufacture of alloys for making coins in Germany, Belgium, France and the United States. It is also extensively used for plating iron and steel articles (by reason of the fact that it does not readily tarnish in the air) and as a catalyst in connection with a number of processes, including one for hardening oils by hydrogenation. (See Hydrogen, p. 251.) Nickel forms two oxides, NiO and Ni 2 O 3 , the monoxide being obtained by heating the nitrate or carbonate. In the form of nickelous hydroxide (Ni(HO) 2 ) it is obtained by adding an alkaline solution to one of a soluble nickel salt, as a light green precipitate which upon drying and heating becomes anhydrous. There is also a soluble chloride (NiCl 2 ), a nitrate (Ni(NO 3 ) 2 ), and a sulphate (NiSO 4 ,7H 2 O), which crystallizes in prisms, all of which are green in colour and soluble in water. Several sulphides are known ; of these, nickel monosul- phide (NiS) is black and insoluble in water and dilute acids. The carbonate (NiCO 3 ) (a crystalline compound in- soluble in water), the chloride, the cyanide (Ni(CN) 2 -4H 2 O) (which is insoluble in water), the nitrate, the sulphate, and the double sulphate of nickel and ammonium (NiSO 4 . (NH 4 ) 2 SO 4 .6H 2 O) (which is soluble in water), are all used in nickel plating, whilst the chloride is also used in the preparation of sympathetic ink, etc. Nickel Carbonyl is a colourless, volatile liquid soluble in alcohol, of sp. gr. 1-3185, which boils at 43 C., and its vapour explodes at 60 C. The compounds of nickel impart a reddish-yellow colour to a fused bead of borax. NICOTINE (C 10 H 14 N 2 ) An oily, colourless, alkaloidal liquid of sp. gr. 1-009, constituting the acrid basic principle of 332 NICOTINE NITRE CAKE NICOTINE (Continued) tobacco, in which it is found present in amount varying from 2 to 8 per cent. Nicotine is not present in the seed of the plants but appears in the young plant immediately the chlorophyll begins to function, and originates in the leaf. 4 It is soluble in water, alcohol, and ether. Preparations of it are extensively used for horticultural purposes as an in- secticide, also as a dip for the destruction of ticks and other pests on the wool of sheep. NIGROSINES A class of black dyes prepared by heating aniline and its hydrochloride with nitro-benzene and a metal. They are of various solubilities some in water, some in alcohol, and others in oil and are used in making polishes, varnishes, inks, and in the dyeing and leather trades. NIOBITE Another name for the mineral columbite. NIOBIUM See Columbium. NITON (Nt) Atomic weight, 222-4. A rare mert element of recent discovery, being a radium emanation soluble in water, prepared by heating a radium compound or by dissolving it in water and pumping off the gases slowly generated from it, and from which it is obtained by first of all removing any associated oxygen, hydrogen, carbon dioxide, and nitrogen, thus leaving the niton (which liquefies at from - 150 to - 170 C.) from which in turn the generated helium may be pumped off. It can be condensed to the solid state, and both it and the liquid forms are phosphorescent. It is said to spontaneously decompose into helium and other substances. NITRATES See Nitrogen Compounds. NITRATION A term given to a chemical process by which, using, generally, strong nitric acid, the nitro group (NO 2 ) is introduced into organic compounds, as illustrated by the production of nitro-benzene (C 6 H 5 NO 2 ) from benzene (C 6 H 6 ). Again, toluene (C 7 H 8 ) can by the action of strong nitric acid, be converted successively into mononitro- toluene (C 7 H ? NO 2 ), dinitro-toluene (C 7 H 6 (NO 2 ) 2 ), and tri- nitro-toluene (C 7 H 6 (NO 2 ) 3 ). (See Explosives.) NITRE See Potassium. NITRE CAKE See Sodium (Hydrogen Sulphate). NITRIC ACID NITROGEN 333 NITRIC ACID See Nitrogen and Nitrogen Fixation. NITRIC ETHER See Ethyl Nitrate. NITRIDES Magnesium, boron, silicon, titanium, and some other elements combine with nitrogen at a red heat to form nitrides, and these are decomposed again by the agency of steam, thus yielding ammonia. Aluminium nitride is now an article of some commercial importance. See Aluminium (p. 24) and Chemical Compounds (p. 102). NITRIFICATION A process by which ammonia and other nitrogenous substances present in soil are converted into nitrates by the action of micro-organisms. Am- monium carbonate, for example, is first of all oxidized and converted into a nitrite by the agency of one micro- organism, and this is changed by another micro-organism into the state of nitrate, the process requiring the presence of a base. It is known that the presence of calcium sul- phate (gypsum) greatly facilitates the nitrification of urine. Nitrifying micro-organisms exist to a depth of about 6 feet in soil, but nitrification is practically confined to the surface, air being essential to the process. The purification of sewage by filtration through soil is largely due to nitrification. (See Bacteria, Soil, and Microbes.) NITRILES Derivatives of hydrocyanic acid, the hydrogen in the HCN being replaced by radicals for example, aceto- nitrile or methyl cyanide (CH 3 .CN). NITRITES See Nitrogen. NITROGEN and its Compounds Nitrogen (N) atomic weight 14, and melting-point -210 C. is contained in the air, of which it makes about four-fifths, while in com- bination, it occurs as Chili nitre or saltpetre in Chili, Peru, and elsewhere, or crude sodium nitrate (NaNO 3 ) which is largely employed as a nitrogenous fertilizer or dressing for agricultural purposes. It is also found in combination as potassium nitrate in the form of nitre or saltpetre (KNO 3 ) in certain soils in India and Ceylon, and as a constituent of many animal and vegetable substances. It can be obtained in quantity by the liquefaction of air and boiling off the nitrogen at - 195*5 C- (See Oxygen.) Nitrogen can be readily made, in the laboratory, from the air by the abstraction of the oxygen for example, by the use of alkaline potassium pyrogallate solution, which has a great affinity for oxygen, speedily absorbing it from 334 NITROGEN AND ITS COMPOUNDS NITROGEN (Continued) a quantity of air confined in a closed vessel, and leaving the nitrogen unabsorbed. Similarly, when phosphorus is burned in air it combines with the oxygen to form phos- phorus pentoxide, leaving nearly pure nitrogen. It can also be made by passing a stream of air over metallic copper heated to redness, when the oxygen of the air combines with and is fixed by the copper, forming cupric oxide, and nitrogen gas passes over. Every living thing contains nitrogen, which is a colour- less gas without taste or smell, nearly insoluble in water (i volume of which at o C. dissolves only 0^0235 volume of the gas), and in its free state is what is termed a very inert chemical substance. In other words, it is very inactive and exhibits but little tendency to enter into chemical combination with other substances. It can, however, be prepared in a much more chemically active (and therefore probably allotropic (isotopic)) form by an electrical process ; moreover, in combination it becomes extremely active. A corona discharge at 20,000 volts from a fine wire is stated to be capable of transforming 4 per cent, pure nitrogen into its activated form, and in this state it will combine with hydrogen to form ammonia, with oxygen to form oxides, and with various metals to form nitrides. This activated nitrogen is more stable than activated hydrogen, and persists for some hours. It exhibits a glow, and it will attack acetylene and other gases containing carbon, thus producing cyanogen com- pounds. Ammonia (NH 3 ) One of the most important combina- tions of nitrogen is ammonia, the salts of which are for the most part obtained from the ammoniacal liquor of gasworks, for which purpose the gas liquor is treated with lime and distilled, the ammonia being thus driven over and condensed in water, or passed into sulphuric or hydrochloric acid, forming respectively ammonium sulphate ((NH 4 ) 2 SO 4 ) or chloride (NH 4 C1). A process (Cobb's) recently devised for recovering ammonia from coal consists in washing the gas in a solution of zinc sulphate, thus causing the precipitation of zinc sulphide, accompanied with the production of ammonium sulphate in solution. The zinc sulphide is filtered off and roasted, thus producing the oxide and sulphur dioxide gas, and by suspending the oxide in water and exposing it to the roaster gas zinc sulphate is re- generated for use over again. NITROGEN AND ITS COMPOUNDS 335 NITROGEN (Continued) The ammonium sulphate is recovered from its solution by evaporation. Ammonia is very soluble in water, which, at the ordinary temperature of the air, absorbs 727 times its own volume of the gas, and at o C. 1,148 volumes. The solution is colourless, strongly alkaline, and of characteristic pungent odour. Ammonia has been produced on a commercial scale from a mixture of nitrogen and hydrogen gases contained under pressure and exposed to a high temperature, using a catalytic agent to effect the combination. (See Nitrogen Fixation.) The ammonium radical (NH 4 ) which is capable of replacing an atom of hydrogen in acids has not been isolated. Ammonia is extensively used in connection with re- frigerating appliances, and some of its salts for rendering wood and other materials non-inflammable. In 1913 the world's ammonia production in terms of sulphate amounted to 1,389,790 tons, the essential sources being gasworks, coke-ovens, gas producers, shaleworks, ironworks, and bone and other carbonizing works. Ammonium Sulphate ((NH 4 ) 2 SO 4 ) is largely used as a nitrogenous fertilizer for agricultural purposes and for the manufacture of ammonia-alum (see Alums) and other com- pounds. The commercial quality of sulphate employed for agricultural use contains about 24^ to 25 per cent, ammonia. In 1914 the production of this compound in the United Kingdom was as follows : Gasworks 176,000 tons. Ironworks... ... 16,000 Shaleworks 63,000 ,, Coke and carbonizing and pro- ducer gasworks ... ... 171,000 ,, Total 426,000 tons. Ammonium Nitrate (NH 4 NO 3 ), as prepared from am- monia and nitric acid, is used in the making of the smokeless and flameless explosive named roburite. During the recent war, the United States of America produced ammonium nitrate by means of a process which 336 NITROGEN AND ITS COMPOUNDS NITROGEN (Continued) consisted of the double decomposition of Chili saltpetre and ammonium sulphate as expressed in the equation : 2NaNO 3 + (NH 4 ) 2 SO 4 = 2NaSO 4 + 2NH 4 NO 3 . (See Explosives.) Ammonium Chloride, as prepared from gas liquor, is puri- fied by sublimation, and is then a colourless, crystalline substance, soluble in cold water to the extent of about 33 per cent., and is known commercially by the name of "sal-ammoniac." It is manufactured on a large scale, being used in medicine, in dyeing operations, in electric batteries, as a fertilizer, in galvanizing, and in the prepara- tion of a cement for fixing iron in stonework (made of iron filings mixed with i or 2 per cent, sulphur and moistened with a solution of the sal-ammoniac). There are several ammonium carbonates, including the commercial article, which is made by heating a mixture of ammonium sulphate and ground chalk to redness and con- densing the generated vapours. It is a mixture of ammo- nium hydrogen carbonate ((NH 4 )HCO 3 ) and ammonium carbamate ((NH 4 )(NH 2 )CO 2 ) from which the carbamate can be washed out with alcohol and has a strong am- moniacal odour. Ammonium Carbonate ((NH 4 ) 2 CO ? ) can be obtained from the commercial compound by passing ammonia gas into a strong solution, but upon exposure to air it gives off ammonia and is changed back to the compound NH 4 HCO 3 , a body which, when crystallized in a pure, dry state, does not smell of ammonia. Ammonium Phosphate ((NH 4 ) 2 HPO 4 ) A white, crystal- line salt, soluble in water; used in medicine, fireproofing, etc. Sal- volatile is a dilute solution of ammonium carbonate. There are a number of other ammonium compounds used commercially, including the oxalate, the molybdate, the perchlorate, and the sulphocyanide. Ammonium acetate (NH 4 (C 2 H 3 O 2 )) is used medicinally as a sudorific (Liquor ammonii acetici). Nitric Acid (HNO 3 ) is a very important nitrogen com- pound, and is formed in a variety of ways, but the method by which it is, in the main, commercially produced is by the action of sulphuric acid (H 2 SO 4 ) upon sodium nitrate NITROGEN AND ITS COMPOUNDS 337 NITROGEN (Continued) (NaNO 3 ). The first stage of the process is represented by the equation : NaN0 3 + H 2 S0 4 = NaIiSO 4 + HNO 3 , and by pushing the heating further there is a secondary change, as follows : NaNO 3 + NaHSO 4 = Na 2 SO 4 + HNO 3 . The operation is generally carried out in cast-iron eggs or cylinders lined with fireclay, under the influence of heat, the nitric acid passing over in the form of vapour, which is condensed. In practice, nearly equal parts of purified Chili nitrate and sulphuric acid are subjected to distillation, and the strength of the acid which is employed, depends upon the kind of nitric acid that is required, concentrated sulphuric acid of about 1 60 Twaddell being used for making strong nitric acid, and that of about 140 Tw. (ordinary Glover tower acid) being used for production of weak nitric acid. The so-called " fuming " nitric acid contains upwards of 86 per cent. HNO 3 , and has a specific gravity of about 1-48- It is very corrosive, and in contact with many organic substances causes their combustion. The ordinary commercial nitric acid, known as "aqua fortis," contains about 65-5 per cent. HNO 3 . Nitric acid is colourless when pure and is a strongly fuming hygroscopic, corrosive liquid with a sp. gr. of 1-53, which attacks many metals with avidity and forms by combina- tion therewith or with their oxides, a large number of corresponding nitrates. It is also a powerful oxidizing agent and its uses in- dustrial chemistry are many and of great importance, in including its employment in the manufacture of the explosives nitro-glycerine, gun-cotton, etc. (See Explo- sives.) Nitrates in the soil are produced by the slow oxidation of ammonia (derived from nitrogenous animal matter) in the presence of air and an alkali, and this process probably accounts for the natural deposits found in Chili and else- where. (See Nitrification.) Nitrogen Oxides There are six of these, having the formulae N 2 O, NO, N 2 O 3 , NO 2 , N 2 O 4 , and N 2 O 5 ; and there are three acids corresponding respectively to the oxides N 2 O, N 2 O 3 , and N 2 O 5 . 22 338 NITROGEN OXIDES NITROGEN (Continued) Nitrous Oxide (N 2 O), known also as laughing gas, can be obtained by gently heating ammonium nitrate, when it splits up into N 2 O and water or by heating a mixture of sodium nitrate and ammonium sulphate to 230 C. and collecting the gas over mercury. It is a colourless gas, soluble in water to the extent of I "35 volumes of the gas in i volume of water at o C., of a faint not unpleasant odour, and when breathed for a short time, induces excitement and in some cases laughter. It is used to some extent as an anaesthetic in dentistry and is easily liquefied to a colourless, mobile fluid which can be frozen solid. Nitric Oxide (NO) is obtained by the action of nitric acid of sp. gr. i "2 upon copper or mercury, when the nitrate of the metal passes into solution and the gas (NO) is generated. It is colourless and enters into combination with atmo- spheric oxygen to form red-brown irritating vapours of nitrogen peroxide. Nitrogen Trioxide (N 2 O 3 ) is made by exposing a mixture of nitric oxide and nitric peroxide to a temperature of 20 C., when it is produced as a bluish-green fluid. Nitrogen Peroxide (NO) can be prepared by passing a mixture of 2 volumes or nitric oxide with i volume of oxygen through a tube surrounded by a freezing mixture. At low temperatures it is a colourless, crystalline compound which melts at - 9 C., and at higher temperatures it takes on a yellow and then an orange colour. It boils at 22 C. and gives off reddish-brown vapours; in fact, it is dis- sociated as the temperature rises, and at 140 C. it is entirely resolved into NO 2 so that the crystalline substance from which it is produced is, for various reasons, regarded as having the constitution represented by N 2 O 4 . According to a recent report, an investigation made on behalf of the Medical Research Committee has provided evidence that the so-called " active oxygen " of fresh country air is not ozone but nitrogen peroxide. This, however, cannot be regarded as proven, for although it may at times be present as a result of electrical action by lightning, peroxide of hydrogen is more often present as an atmospheric constituent particularly in the neighbourhood of pine woods. (See Hydrogen Peroxide.) Nitrogen Pentoxide (N 2 O 5 ) is a white, solid, crystalline NITROGEN NITROGEN FIXATION 339 NITROGEN (Continued) substance which melts at 30 C. with partial decomposition, and when suddenly heated, is apt to explode with violence. Placed in contact with water, it produces nitric acid N 2 5 +H 2 It can be prepared by withdrawing the elements -of water from nitric acid by means of phosphorus pentoxide 2HNO 3 + P 2 O 5 = 2HPO 3 + N 2 O 5 the mixture being cautiously made and kept cool at first, and then gently heated, when the N 2 O 5 distils over and can be condensed in a refrigerated receptacle. Hyponitrous Acid (H 2 N 2 O 2 ) is an unstable substance and has no commercial importance. Nitrous Acid (HNO 2 ) is not known in the pure state, but its salts (the nitrites) are stable compounds and can be pre- pared by heating the nitrates above their fusion-point, when oxygen is given off and the nitrites are obtained by this reduction ; for example KNO 3 =KN0 2 + 0. When the nitrites are subjected to the action of dilute acids they are decomposed, brown vapours being given off, whereas the nitrates are stable under this treatment. Nitrogen Trichloride Obtained from ammonium chloride by the action of chlorine is a thin, oily, very volatile liquid of pale yellow colour and sp. gr. 1-65, having an irritating pungent odour. It is one of the most dangerous explosives, decomposing with great violence when exposed to sunlight or brought into contact with grease, turpentine, and many other substances. There is a corresponding bromide and a crystalline iodide represented by the formula N 2 H 3 I 3 . NITROGEN FIXATION Of the various processes for the so-called fixation of nitrogen, some depend upon the direct union of nitrogen with oxygen under the influence of the electric arc at a temperature of about 3,000 C., but these can only be economically carried out where cheap and abundant supply of water-power is available for production of the requisite electric energy. When a current of air is passed rapidly through the electric arc, nitrogen peroxide (NO 2 ) is formed, and at 340 NITROGEN FIXATION NITROGEN FIXATION (Continued) ordinary temperatures and in the presence of water this product is partially convertible into nitric acid. The Hausser process, which is at present in the experi- mental stage, is one in which the heat caused by the explosion of a mixture of combustible gas and air is used to bring about the union of nitrogen and oxygen, oxides of nitrogen being produced which can be absorbed in water whilst power is generated simultaneously. The nitrous gases produced by these methods are passed into vertical iron cylinders lined with acid-proof stone in which the nitric oxide previously produced is oxidized by atmospheric oxygen into nitric peroxide, the gases being finally condensed by contact with water in washing towers into nitric acid. Nitric acid is also produced to some extent on a com- mercial scale by the oxidation of ammonia, and there are considerable expectations based upon this method of production by catalytic agents, including platinum gauze. In this process, a mixture of air and ammonia, containing about 10 per cent, of the latter, is passed through platinum gauze placed between washers of asbestos board or nickel- chrome sheet, heated in the first place by a plumber's blow- pipe, but maintained subsequently at a cherry-red heat by the chemical change which is involved. The Haber process, which was in use in Germany before the war, is based upon the direct union of nitrogen and hydrogen at a temperature of from 500 to 700 C., main- tained by means of an electric coil and under a pressure of approximately 200 atmospheres, in the presence of a catalyst, thus producing ammonia, which can be subse- quently converted into nitric acid and ammonium nitrate by oxidation, or into ammonium sulphate. Metallic osmium has been found to serve well as a catalyst but is too expensive for use on a manufacturing scale, and an activated iron catalyst such as ferro-molybdenum is employed in practice. In the Claude process, nitrogen boiled off from liquefied air is admixed with hydrogen gas in suitable proportions and the mixed gases subjected as in the Haber process but under a greatly increased pressure up to from 900 to 1,000 atmospheres ; so that whereas in the Haber process only from about 10 to 12 per cent, of the gases is transformed into ammonia, from 30 to 36 per cent, transformation is effected, and the product is obtained, owing to the great pressure, in liquid form. NITROGEN FIXATION-NITRO-PHENOLS 34' NITROGEN FIXATION (Continued) The ammonia can be oxidized by air on the surface of a solid catalyst such as platinum wire gauze or ferric oxide at a temperature of about 650 to 700 C., the main re- actions being as follows : 4 NH 3 + 5O 2 = 4NO + 6H 2 O, the nitric oxide thus produced being converted into nitric acid by means of atmospheric oxygen and water 4 NO + 3O 2 + 2H 2 O = 4HNO 3 . For this purpose the gases issuing from the converter in which the nitric oxide is produced are cooled to about 30 C. and then passed into the oxida- tion and absorptive towers. It is stated that one plant at Hochst (Germany) for the oxidation of ammonia into nitric acid is capable of pro- ducing the equivalent in nitric acid of 6,500 tons and another of 10,000 tons nitrate of sodium per month. (See also Cyanamide.) NITROGEN TRICHLORIDE See p. 339. NITRO-BENZENE, or OIL OF MIRBANE (C 6 H 5 (NO 2 )), is a yellowish liquid of sp. gr. 1*1986 and boiling-point about 211 C., prepared from benzene by the action of a mixture of sulphuric and nitric acids, and can also be produced by the action of strong nitric acid on turpentine. It has an intense odour of oil of bitter almonds, is soluble in alcohol and ether, and is much used in perfumery and as a flavouring principle, also in the dye industry. There are several di-nitro-benzenes (C 6 H 4 (NO 2 ) 2 ) and tri-nitro-benzenes (C 6 H 3 (NO 3 ) 3 ) respectively. NITRO-CALCITE Native calcium nitrate. NITRO-CELLULOSE See Explosives. NITRO- GLYCERINE See Explosives. NITRO-HYDROCHLORIC ACID See Aqua Regia. NITRO-LIME (Calcium Cyanamide) See pp. 77 and 148. NITRO -PHENOLS (Ortho, Meta, and Para Compounds) (C 6 H 4 OH.NO 2 ) are all crystalline substances soluble in alcohol and ether, the meta compound being used for manufacturing the dyes known as "rhodamines" (which are closely allied to fluorescein) whilst the para compound is used in making phenacetin, etc. The ortho compound is yellow and melts at 45 C. ; the meta compound is also 342 NITRO-PHENOLSNOTA TION NITRO-PHENOLS (Continued) yellow and melts at 96 C., whilst the para compound is colourless and melts at 114 C. (For Tri-nitro-phenol see p. 190.) NITRO-TOLUENES (CH 3 .C 6 H 4 .NO 2 ) A class of compounds produced by the nitration of toluene. The para compound is a solid, crystalline body employed for making fuchsine and other dyes in common with the ortho compound, which is a liquid substance and can be used in common with nitro-benzene in preparing so-called "oil of mirbane." The para compound melts at 51 C. and boils at 234 C., whilst the ortho compound boils at 218 C. (For Tri-nitro-toluene see p. 191.) NITROSO COMPOUNDS contain the nitroso group N:O ; for example, nitroso-benzene (C 6 H 5 ,N:O). NITROUS ACID See p. 339. NITROUS ETHER (Ethyl Nitrite) (C 2 H 5 (NO 2 )) or SWEET SPIRIT OF NITRE A drug, used as a diuretic and stimu- lant, prepared by the action of nitric acid upon alcohol. It is a yellowish, aromatic, volatile, and inflammable liquid of sp. gr. 0*900, boiling at i6'4 C., soluble in alcohol and ether. NITROUS OXIDE (Laughing Gas) See Nitrogen, p. 338. NOMENCLATURE The terms and names used to identify and classify chemical substances. (See Chemical Compounds, Chemical Interactions, and Elements ; also " Hypo.") NORDHAUSEN ACID Fuming concentrated sulphuric acid originally prepared at Nordhausen in Saxony by the dis- tillation of ferrous sulphate, the gas generated in this way being condensed in ordinary sulphuric acid. It really consists of a mixture of sulphuric acid (H 2 SO 4 ) and sulphur trioxide (SO 3 ). (See Oleum and Sulphur Compounds.) NORMAL STANDARD SOLUTIONS Contain an equivalent weight of the substance, dissolved in i litre (1,000 c.c.), and deci-normal solutions are of one-tenth that strength ; both are used in " Volumetric Analyses." NOTATION The use of symbols and formulae to denote the constitution of chemical substances. (See Chemical Com- pounds, Chemical Interactions, and Elements.) NOVOCAINE NUTMEG OILS 343 NOVOCAINE (or = p. Amino - benzoyl - diethylamino - ethanol Hydrochloride, NH 2 .C 6 H 4 .CO.O.C 2 H 4 .N.(C 2 H 5 ) 2 HC1) A complicated organic substance used as a local anaesthetic in place of cocaine, being less toxic. NTJCLEINS (Nucleo -Proteins) Albuminous substances con- tained in many animal and vegetable tissues. " NULOMOLINE " A proprietary article used, for some pur- poses, as a substitute for glycerine, being a solution of partly inverted sugar of sp. gr. 1-4. NUT OILS Include many varieties, the more important of which are described under their several names. Palm kernels contain about 50 per cent, by weight of a white, solid fat, which, after refining, is used in making margarine, and the residual cake or meal resulting from the crushing and extraction of the oil is a serviceable cattle food. Ground-nuts or earth-nuts contain from about 35 to 40 per cent, of a liquid, palatable oil, and, when freed from the husks, about 45 per cent, of the oil. The residual cake is highly albuminous, that from the decorticated seed sometimes testing above 50 per cent., and is much relished by cattle. Hazel nuts yield 60 per cent, of a pale yellow oil, and walnut oil (formerly called " nut oil ") from the kernel oijuglans regia, is a quick-drying oil, which is green when freshly extracted ; it turns yellow on keeping, is inodorous, and used in painting. Walnuts yield as much as from 50 to 65 per cent, of this oil, which forms a soft soap when saponified with potash. Almond nuts contain about 55 per cent, fat ; beech nuts, 57 per cent. ; brazil nuts, 66 per cent. ; cocoa-nuts, from 50 to 55 per cent. ; filberts, 65 per cent. ; hickory nuts, 67 per cent. ; pea-nuts, 39 per cent. ; pistachio nuts, 51 per cent. ; and pecan nuts, 70 per cent. " Nut Oil " (arachis oil, pea-nut or ground-nut oil) is now largely produced in both China and Japan (particularly in the Yokohama district), also in Senegal, and should not be confounded with true walnut oil, which was wont to be described as " nut oil." (See Arachis Oil.) NUTMEG- OILS The wild oil nutmegs of Myristica sebifera, abundant in South America, yield about 26 per cent, of oil of yellowish colour and sp. gr. 0-870 to 0-925, soluble in alcohol, which can be expressed and used for soap and candle making. Nutmegs are also used as a condiment in cooking and in the preparation of mace. Nutmegs are grown in the Molucca Islands and are also cultivated in Java, Sumatra, Singapore, etc, 344 NUTMEG OILS OCCLUSION NUTMEG OILS (Continued) The oil contains a narcotic body named myristicin (C 12 H 14 3 ). The kernels of the Otoba nutmeg (Myristica otaba), from Colombia, are stated to yield 7-2 per cent, of a colourless, volatile oil, of sp. gr. 0*894 optical rotation +79*55, and refractive index 1-502 ; soluble to the extent of 16 volumes in 90 per cent, alcohol at 15 3 C. NUTRITION See Foods. NUX VOMICA The dried seeds or beans of a species (Sir. Nux vomica) of apocynaceous plants, which grow in Southern Asia and Northern Australia, and yields the two bases strychnine (C 21 H 22 N 2 O 2 ) and brucine (C 23 H 26 N 2 O 4 ). Strychnine is also obtained from the Sty. Colubrina"tree (which grows in the Moluccas and yields so-called snake- wood) and from the Str. S. Ignatii and 5. Tieute. (See Strychnine.) OAK BABE (from Quercus vobur) See Tannin and Gall Nuts. OBSIDIAN A dark green or jet variety of lava, containing the oxides of aluminium, magnesium, potassium, sodium, and silica. (See Pumice.) " OBSIDIANITE " A proprietary brand of fire and acid proof material for use in the construction of "Glover " and " Gay Lussac " towers. (See Sulphuric Acid.) OCCLUSION The property exhibited by certain metals, of absorbing or occluding gases when exposed to them in a heated condition. The behaviour of the metals platinum and palladium in this respect is referred to more par- ticularly under those headings, and in a fine state of division, gold, iron, nickel, copper, aluminium, and lead will all absorb more or less hydrogen gas. Iron also occludes carbon monoxide, and melted silver is capable of occluding oxygen gas when in a molten condition. Apart from the increase in volume, there is no change in the appearance of the metals, but their density is, of course, diminished proportionately. In view of recent investigations concerning atomic struc- ture and the transformation of the chemical elements, it would seem of importance to ascertain whether the gases absorbed by metals as described, differ in any physical or chemical qualifications from those originally exposed to their action. In the Faraday Lecture delivered by Theodore William OCCLUSION ODOUR THEORY 345 OCCLUSION (Continued) Richards to the Chemical Society in ign, it was pointed out that such porosity as occurs in rigid, compact solids, usually permits the passage only of substances which enter into the chemical structure of the solids themselves. Thus, nitrogen cannot free itself from imprisonment within hot cupric oxide, although oxygen can escape ; again, water cannot evaporate into even the driest of atmospheres from accidental incarceration in crystals lacking water of crys- tallization. Palladium, on occluding hydrogen, is obliged to expand its bulk in order to make room for even this small addition to its substance. The behaviour of platinum, nickel, and iron is probably analogous, although less marked. Fused quartz, impermeable when cold, allows of the passage of helium and hydrogen at high temperatures ; but most other gases seem to be refused admission, and very many solid substances appear to act as effective barriers to the passage of even hydrogen and helium, especially when cold ; and he concludes, from a review of the available evidence, that interstices between atoms in solids and liquids must be extremely small in proportion to the size of the atoms themselves, while he raises the question if there are any interstices at all (see Ether and Porosity). He believes that atoms are compressible throughout their whole substance i.e., they may contract or expand, or vibrate within themselves, even when they are so closely packed together as to prevent their surfaces from moving. (See Platinum and Palladium.) OCHRE A name given to a large number of metallic oxides yellow, red, and brown found naturally in a more or less pulverulent form, such as iron or red ochre and molybdic ochre. " Yellow ochre " is a clay coloured with ferric oxide. OCTYL ALCOHOL (C 8 H 18 O) See Alcohols. OCTYLENE See defines and Hydrocarbons. ODOUE THEORY The so-called " residual affinity" theory of the cause of odour, rests upon the view that it arises from the free or unsatisfied affinity of the constituent molecule. To have an odour, a substance must possess this residual or unsatisfied affinity, be sufficiently soluble in the water and the lipoid fats of the nose, and must be volatile. Unsaturated bodies, generally, have distinctly stronger odours than saturated ones. 346 (EN A NTH 1C ETHER OILS (ENANTHIC ETHER (Cognac Oil) (C 9 H 18 O 2 ) A mobile liquid substance used in the preparation of artificial cognac and for flavouring wines ; made from oenanthic acid and ethyl alcohol by the action of sulphuric acid, and prepared commercially from the oxidized products of oil of rue. It is stated to be a mixture of capric and caprylic acids, has a strong vinous odour, and is readily soluble in alcohol and ether. Many fusel oils contain these acids, and some Hungarian wines are known to contain amyl caprate. OIL CAKE The cake remaining after the expression of oils from seeds. Home -manufactured Cakes and Meals. Linseed cake con- taining not less than 8 per cent, oil, cotton-seed cake, undecorticated ground-nut cake, semi-decorticated ground- nut cake, decorticated ground-nut cake, palm-kernel cake, rape cake, copra cake, sesame cake, soya cake, extracted palm-kernel meal, extracted rape meal, extracted soya meal. Imported Cakes and Meals. North American linseed cake, Argentine linseed cake, Canadian linseed cake, Australian linseed cake, Spanish and Portuguese linseed cake, Egyptian cotton-seed cake, decorticated cotton-seed meal, decorticated cotton-seed cake, re-pressed cotton cake, semi-decorticated cotton cake, copra cake, palm-kernel cake, Rangoon rice meal, Italian rice meal, Canadian rice meal, Egyptian rice meal, gluten feed, maize-meal cake. The feeding values of cakes are chiefly represented by their protein constituents. " OILDAG "See Lubricants. OIL OF VITRIOL Strong sulphuric acid (about 98 per cent, strength). OILS There are oils of many kinds, but they may be roughly divided into three classes viz., the essential oils, which are described under that heading and their own names, and are for the most part hydrocarbons ; the petroleum and paraffin class, derived from natural deposits or distillation of coal, lignite, wood, peat, etc., which are also hydro- carbons but of another class ; and fat or fixed oils, derived from animals, vegetables, or fishes, which are obtained either by pressing the nuts, seeds, or organs of the fishes which contain them, or extracting them with solvents, and the more important ones are described under their several names. They are all greasy in character and can be made into soaps by saponification. By a new process, crushed seeds are subjected to dry heat and agitation, whereby all moisture is driven off and the meal is converted OILS 347 OILS (Continued) into a sloppy state, and then centrifugalized at the same temperature. In this way 50 to 75 per cent, of the oil content can be extracted, so that half of the usual pressing or other plant is required to complete the extraction. APPROXIMATE TYPICAL VALUES OR CONSTANTS OF OILS. Name. Sp. Gr. at 15 C. Saponifi- cation Value. Iodine Value. Refractive Index. Melting- Point. Arachis 0-917-0-925 185-196 92-IOI I '4705-1 -4745 -8C. Almond 0-9175-0-9195 189-192 93-101 1-473 - 10 C. (about) Candle-nut... 0-925-0-927 190-195 136-140 i8C. Castanha ... 0-918 193 '5 1 06 0-4 C. Castor 0*95-0-96 176-183 83-86 1-480 Cocoa-nut ... 0-9115 250-258 8-9 1-4566 20-28 C. Cohune 0-868 252 11-13-7 i8-2o C. Cotton-seed 0-922-0*927 193-195 108-116 i'457 Hempseed ... 0-925-0-928 192-193 148 1-448 Linseed 0-932-0-938 188-195 185-195 1-466 Maize 0-92-0-93 188-193 111-123 Olive 0-916-0-918 185-196 79-93 1-469 Palm (butter) 0-92-0-93 2O2 5i '5 27-42C. Palm(nutoil) 0-952 247-6 13*5 2 6-30C. Poppy-seed 0-925-0-926 193-195 131-141 1-457 Rape-seed ... 0-916-0-917 170-179 96-100 1-472-1-475 I7-22 C. Sesame 0-921-0-925 188-193 103-108 i '457 26-32C. Soya-bean ... 0-936-0-940 I92-20O 137-141 1-476 22 - 3 IC. Sunflower ... 0-924-0-926 189-193 129-132 1-461 Tea-seed ... 0-916-0-919 193-4-194 81-7-82-3 z'47-1'47 1 Tung 0-936-0-943 190-195 150-165 1-503 Walnut 0-92-0-93 192-197 142-146 i -4804 Neat's-foot 0-964-0-98 70-75 191-199 1-469 Nut oil of commerce 0-916-0-9185 80-6-96-84 1-4715-1-473 Cod-liver ... 0-92-0-93 171-189 150-167 1-479-1-483 Dugong ... 0-92 i97"5 66-6 Herring 0-92 180-194 130-142 Porpoise ... 0-926 195-256 88-119 Sardine 0-93 190 180-193 1-48 Seal 0-924-0-926 189-196 127-159 1-474 Sperm (whale) ... 0-925 188-193 1 20 1-46-1-47 Tuna 156 The fatty or fixed oils are again roughly divisible into two classes known as drying and non-drying. The former, such as linseed, hemp, and poppy oils, readily absorb 348 OILSOLEFINES OILS (Continued) oxygen from the air, thus forming a skin and gradually drying up, whilst the latter class (including almond, olive, and castor oils) do not so pronouncedly dry up in this way. (See Essential Oils, Fats, and Petroleum.) Polymerization is most easily observed with highly un- saturated oils, such as tung and linseed oils, but is not altogether peculiar to them. It is shown by gelatinization and by increase in density, viscosity, and mean molecular weight, and a decrease in the iodine value. OILS (Hydrogenation of) See Hydrogen, p. 252. "OKOL" A disinfectant and larvicide, consisting of an emulsion of phenoloids ; miscible with water. OLEFIANT GAS See defines. OLEFINES A class of unsaturated hydrocarbons of ascend- ing boiling-points and general formula CH 2 , from which the glycols are derived, including Ethylene (C 2 H 4 ) of boiling-point - 102-5 c - Propylene (C 3 H 6 ) - 4 8C. Butylene (C 4 H 8 ) - 5 C. Amylene (C 5 H 10 ) +39C. Hexylene (CgH 12 ) 68 C. Heptylene (C 7 H 14 ) 95 C. Octylene (C 8 H 16 ) 124 C. etc. The first three members of the group are colourless gases, and when the liquid members are reached (with amylene) they diminish in mobility, while the higher ones, like cerotine (CgjH^) and melene (C^H^), are solid, and similar to paraffin. These last-named substances can be obtained from china wax and beeswax respectively by distillation. Most of them are soluble in alcohol and ether, but not in water. The best known member of the series is ethylene or olefiant gas, and is prepared by the action of sulphuric or syrupy phosphoric acid upon its corre- sponding alcohol (C 2 H 6 O) by the abstraction of water C 2 H 6 = C 2 H 4 +H 2 0, or by passing carbon monoxide and hydrogen over finely divided platinum or nickel at 100 C. It is one of the products of the distillation of wood and coal and enters in OLE FINES OLIVE OIL 349 OLEFINES (Continued) small proportion into the composition of coal gas. It is but slightly soluble in water and alcohol, burns with a luminous flame, and was used in preparing mustard gas. (See Gassing.) By combination with chlorine, ethylene forms ethylene dichloride (C 2 H 4 C1 2 ). (See Hydrocarbons.) OLEIC ACID (Ci 8 H 34 O 2 ) in combination with glycerine (as olein) is contained in most fats and fixed oils, particularly the latter, and when pure is a tasteless, odourless, crystalline body, of sp. gr. 0-8908, which melts at 14 C, and is very soluble in alcohol and ether. It absorbs oxygen from the air and turns yellow upon exposure. Upon saponification with alkalies it yields combinations in the nature of soft soap. The natural oils containing olein belong to the " non-drying " class that is to say, they do not thicken, and more or less dry up upon exposure to the air. Nitrous acid converts oleic acid into a solid stereo- isomeric modification known as elaidic acid. OLEIN The glyceride of oleic acid, being an oily body found present in many natural fats, and which yields oleic acid (a fatty acid) and glycerine upon hydrolysis. (See Fats.) " OLEO " The fluid oil otherwise known as " premier jus," expressed from beef-fat, and used in making " margarine." OLEO MARGARINE Another name for margarine. OLEO-RESINS See Balsams, Gums, and Resins. " OLEOSOL "See Lubricants. OLEUM See Sulphur (sulphuric acid). OLIBANUM A gum resin used as incense, obtained from a tree of the terebinthaceous order growing in Arabia. OLIVE OIL An oil expressed from the fruit of the olive-tree (Oka Europea), extensively grown in Southern Europe, and of great value as a food and for the manufacture of certain kinds of soaps. The pure oil is of a pale yellow or greenish- yellow colour and agreeable taste, has a sp. gr. of 0-916 to 0-918, a saponification value of 185 to 196, and an iodine value of 79 to 93. It contains about 75 per cent, of glycerides (glyceral esters of palmitic, stearic, and oleic acids, chiefly oleic). It has recently been ascertained that when olive oil is heated with mannitol in the presence of a small amount of 350 OLIVE OIL OPIUM OLIVE OIL (Continued) sodium ethylate the glycerol (glycerine) can be replaced by it, and the product is far superior in all respects to the original olive oil as a food fat. (See Mannite.) OLIVENITE A native arsenateof copper (4CuO. As 2 O 6 + H 2 O). OLI VINE A mineral magnesium silicate with varying amounts of ferrous silicate ((MgFe) 2 SiO 4 ). ONION OIL A yellowish liquid of penetrating odour and sp. gr. about 1*04, containing allyl compounds, used in flavouring. Garlic oil contains allyl sulphide ((C 3 H 5 ) 2 S). ONYX or CHALCEDONY A native coloured form of nearly pure silica (a chalcedonic variety of quartz). (See Silica.) OOLITE Varieties of limestone rocks. OPAL An uncleavable variety of colloidal quartz. (See Silica.) OPAQUE Not transparent. OPIUM The dried juice extracted from the seed vessels of the poppy (Papaver somniferum), containing, amongst other sub- stances, several alkaloids, including about from 10 to 18 per cent, of morphine (C 17 Hj 9 NO 3 .H 2 O) a powerful drug used medicinally as a soporific (sleep producer) and from 2j to 10 per cent, of narcotine (C M H,,NQ.). Other alka- loids associated with these are codeine (C 18 H 21 NO 3 H 2 O), thebaine (C 19 H 21 NO 3 ), papaverine (C 20 H 21 NO 4 ), and narceine (C 23 H 27 NO 8 ,3H 2 O). It is collected chiefly in Asia Minor, Turkey, India, and Egypt. The trade before the Great War was chiefly in the hands of Turkey, the Indian opium poppy of the same species having a smaller morphine content, but by selection and crossing of various varieties, it is hoped to produce opium of the desired qualities, and already chemical investigations have disclosed races yielding as much as 18 per cent, morphine. Morphine melts at 254 C. 1 all of which are white, cry- Codeine 154*9 C. !- stalline bodies, soluble in Thebaine 193-0 C. J water, alcohol, and ether. Papaverine melts at 147-0 C., is insoluble in water, but soluble in hot alcohol and benzene. Narceine is soluble in alcohol, but hardly soluble in water. Narcotine melts at 176 C., is a white, crystalline body, insoluble in water, but soluble in chloroform and to some extent in alcohol and ether. OPOPANAXORES (TREATMENT OF) 351 OPOPANAX A resinous gummy substance from the roots of Pastinaca opopanax growing in warm climates. The dried juice from Turkey and the East Indies is brought in lumps which have a peculiar odour and a bitter acrid taste. It is used in perfumery. OPTOPHONE See Selenium. ORANGE OIL From the peel of the fresh fruit the sweet oil from Citrus aurantium and the bitter oil from C. bigaradia. Both are used for flavouring purposes. The sweet oil exhibits a sp. gr. of from 0*847 to 0*851 ; optical rotation, + 97 to 100; and refractive index, i'47io to 1*4742. The bitter oil f sp. gr., 0-852 to 0-856 ; optical rotation, + 90 to 94 ; and refractive index, 1*4730 to 1*4770. ORANGE-FLOWER OIL (Neroli Oil) has a sp. gr. of 0-87 to 0-88 and an optical rotation of +0 to 5. ORANGITE See Thorium. ORCHIL A dye prepared from certain lichens by treatment with a solution of potash or milk of lime, from which extracts the " colouring acids " are precipitated by the action of hydrochloric or acetic acid. " French purple " is an orchil dye. (See Archil.) ORES Compounds of metals as found in nature, derived from the outer crust of the earth, and concentrated by natural processes. ORES (TREATMENT OF) The treatment of ores with the view of separating their various metallic or other constituents necessarily varies according to their nature, and many of the processes are described under the headings of the metallic elements (see Lead, for example) ; but a method of separation now largely used, particularly in respect of the lead and zinc sulphides, is that known as " flotation," in which various liquids, such as amyl alcohol, creosote oils, eucalyptus oil, pine spirit, and turpentine, are employed, while in the case of copper ores petroleum products are favoured. The powdered ore is mixed with water in the proportion of about i ton to 4 or 5 tons, and there is then added from to 2 Ib. of the "flotation" oil so as to produce frothing when air is blown through the mixture, with the result that the sulphide ore concentrates in the froth, while the heavier quartz and other impurities sink to the bottom of the tank or remain in slight suspension in the water. Sometimes an oxidizing agent is also added. The important factors are agitation, solubility or mis- 352 ORES ORGANIC ANALYSES ORES (TREATMENT OF) cibility of the flotation liquid (usually oil), the surface tension, and the size of the ore particles, these factors being interdependent, as the [more the oil goes into solu- tion, the more the bubbles are diminished. The selective agency by means of which the flotation method separates substances like galena from its associated quartz and calcite is said to be in the main dependent on the contact angle formed by the oiled surfaces. The froth may be broken up by spraying wich water, but usually the concentrates are passed direct into a pressure filter, thus collecting the solid separated ore for such further treatment or refinement as may be expedient. The froth-flotation process has also been applied to the purification of coal by the elimination of shale and other waste material with which it may be associated. (See p. 125. ) The world's production of the more important metals (obtained largely from sulphide ores) in 1913, has been reported as follows: Copper, 1,006,000 tons; lead, 1,187,000 tons ; spelter, 998,000 tons ; and tin, 129,000 tons; and it is computed that to produce these quantities, approximately 20,000,000 tons of ores had to be dealt with, chiefly by roasting them or their concentrates. ORGANIC ANALYSES The percentic amounts of carbon and hydrogen contained in organic substances are deter- mined for the most part by a process of combustion, and, taking sugar by way of example, the method may be described as follows : A definite weight is taken and, after admixture with oxide of copper (so as to moderate the Combustion Furnace as in Use. action of the oxygen gas, as referred to later), placed in a little vessel or boat small enough to be pushed into a length of glass combustion tubing. The tube containing the boat is then placed in a so-called combustion furnace (as shown in figure), suitably equipped and connected with, first of all, ORGANIC ANALYSES 353 ORGANIC ANALYSES (Continued) a drying-tube of previously ascertained weight, and then with so-called potash bulbs charged with a solution of potassium hydroxide of sp. gr. 1-26, also of previously ascertained weight. This so-called " combustion furnace " is extensively employed for exposing solid substances up to a red heat (but below that of the melting-point of the combustion- tube that is employed) to a current of air, oxygen, or other gas, in order to study the effects produced, by subsequent examination of the gaseous and residual products, and still more often for the analytical determina- tion of the constituents of organic substances. It consists of a great number of Bunsen burners set in a row, and all rising up from a larger gas-supply pipe below, with which they are connected. They sometimes terminate in and are surrounded by hollow perforated cones or blocks of earthen- ware, as shown by d in illustration, which has the effect of breaking up the rlame and bringing the entire mass to a glowing red heat when in use. The framework is of iron, and so constructed that when the furnace is in use, the heat can be more or less concentrated on the combustion-tube by means of earthenware tiles arranged at the sides, and which can also be placed over the top of the channel (running along and over the tops of the burners below) in which the combustion-tube rests. Reverting now to the analysis of sugar, a current of dried oxygen gas is passed through the combustion-tube, while gradually heated to redness in the furnace. This causes the decomposition of the sugar, which consists of carbon, hydrogen, and oxygen (C 12 H 22 O 1]L ), with the result that the carbon is burned off as carbon dioxide (CO 2 ) and the hydrogen as water (H 2 O). The water is absorbed by the sulphuric acid or calcium chloride con- tained in the drying-tube (A) and the carbon dioxide is absorbed by the potash in the bulbs (B) ; and these being severally weighed after the combustion is completed, it is known that the increases in weight of the two appliances are due to these absorbed products, and knowing how much carbon and hydrogen are severally contained in given quantities of carbon dioxide and water, it is easy to calculate the quantities therefrom. These will be found to make up so much of the weight of the sugar, and the other part necessarily consists of oxygen, which is the only other constituent of the sugar, and which it is therefore unnecessary to specifically determine otherwise. 23 354 ORGANIC ANALYSES-ORPIMENT ORGANIC ANALYSES (Continued) - To determine the nitrogen content of organic substances the combustion is, in the main, conducted as already de- scribed, but a current of carbon dioxide is first of all used to clear out the air from the combustion apparatus, and afterwards to sweep out any remaining nitrogen gas, which is collected by displacement in an inverted tube of mercury standing in a dish of potassium hydrate, and measured (making due corrections for temperature and pressure), and from this measurement its weight is calculated. Any oxygen that may be admixed with the nitrogen gas is first of all absorbed by introducing an alkaline solution of pyrogallic acid. (See Pyrogallic Acid.) In other cases, instead of using cupric oxide, fused lead chromate reduced to powder is employed, and there are well-understood methods of determining the percentages of any other constituents, such as sulphur or phosphorus. (See also Drying-Tube and Potash Bulbs.) ORGANIC BASES See Bases. ORGANIC MATTER See Carbon. ORGANIZED Arranged in definite form or structure, such as cells, fibres, membranes, hair, skin, etc. ORGANO-METALLIC COMPOUNDS -Comprise a numerous class of colourless, mobile, liquid substances of volatile character in which organic radicals, such as the alkyl groups, are combined with metals ; for example, zinc methyl (Zn(CH 3 ) 2 ), zinc ethyl (Zn(C 2 H 5 ) 2 ), aluminium methyl (A1(CH 3 ) 3 ), and lead tetra-methyl (Pb(CH 3 ) 4 ). They cor- respond to the chlorides from which they are derived, are decomposed by water, and burn explosively in the air. In addition, mercury, tin, and some other metals yield phenyl derivatives mercury phenyl (Hg(C 6 H 5 ) 2 ), for example, which is obtained by the action of sodium amalgam on bromobenzene. By oxidation, zinc ethyl yields zinc ethylate (Zn(C 2 H 5 O) 2 ), and this by further oxidation gives zinc acetate (Zn(C 2 H 3 O 2 ) 2 ). ORIGANUM OIL A variety of thyme oil from Trieste, Cyprus, and Smyrna ; sp. gr., 0-915 to 0*98 ; rotation, o to 13. (See Thymol.) ORMOLU k (Mosaic Gold) A variety of brass containing more copper and less zinc than ordinary brass, resembling gold in appearance. ORPIMENT See Arsenic Compounds. ORRIS OIL OSMOSIS 355 ORRIS OIL A yellowish, semisolid, fatty substance distilled from the rhizome of Iris Florentina, containing myristic acid, oleic acid, and some esters. It melts at 44 to 50 C., is soluble in alcohol and ether, and is used in making perfumes and cosmetics. Irone, a methyl ketone (C 13 H 20 O), is the odoriferous principle of the iris root, and probably that of the violet also. Irone is, in fact, the basic source of several compounds used for the manufacture of violet essence. (See also lonone.) ORTHITE See Lanthanum. ORTHOCLASE A kind of felspar potassium aluminium silicate. ORTHO-COMPOUNDS are substitution products derived from benzene, in which the substituting radicals or groups are constitutionally situate in certain definite positions in the nucleus ortho-cresol, for instance. ORTHO-CRESOL See Cresol. OSAGE ORANGE A material obtained from the bark of the osage orange tree, indigenous in the United States, containing some 25 per cent, tannin, and used also as a dye. OSMIUM (Os) Atomic weight, 191 ; sp. gr., 22-47; melting- point, 2,700 C. A rare element of the platinum group, and the most refractory; found in alloyed association with iridium in certain platinum ores, and notably in so-called osmiridium, in parts of which the osmium content runs as high as from 30 to 40 per cent. It is a hard, bluish- white, and the heaviest known metal, possessing catalytic pro- perties. It can be prepared from its oxides by reduction ; is known in crystalline and amorphous forms, and burns brightly when strongly heated, forming osmium tetroxide. The amorphous variety is dissolved by aqua regia and the tetroxide is thus produced, but the compact form is insoluble in all acids. Four oxides are known viz., OsO, Os 2 O 3 , OsO 2 , and OsO 4 and there are salts corresponding to the sesquioxide. Three chlorides are known OsCl 2 , OsCl 3 , and OsCl 4 . OSMOSIS The mixing of two liquids separated by a porous diaphragm ; for instance, if a bladder containing alcohol be placed in a basin of water, some of the spirit will pass through the diaphragm into the water, and some of the water will pass through it into the alcohol. In most cases the quantities of the two different liquids travelling in opposite directions are unequal. 356 OSMOSIS OXALATES OSMOSIS (Continued) If a porous earthenware vessel be substituted for the animal membrane and the pores thereof covered by the deposition thereon of a finely divided precipitate such as copper ferrocyanide (thus producing a semipermeable surface), it is found that, using a solution of sugar, water will pass therefrom through the surface, but the sugar dis- solved therein will not permeate. If, therefore, a cell of unglazed porcelain be prepared coated internally in this way, charged with a solution of sugar and then immersed in water, the liquid will rise within the cell or tube to a certain extent above the level of the surrounding water, by reason of the passage of the water through the cell, no sugar passing out ; but when a certain pressure is reached, equilibrium is established, and water then passes in each direction at equal rates ; so that by connecting such an appliance with a manometer the pressure reached can be measured and recorded as the " osmotic pressure." Expressed otherwise, osmosis represents the increase in the volume of the dialyzing fluid in the interior of the cell, and this phenomenon is always observed whenever a so-called dispersoid is brought in contact with a less con- centrated one. At the same temperature and strength of solution, different substances exhibit different pressures, and it has thus been found that the analogy between the laws governing these phenomena and those relating to gaseous pressure is close, and that osmotic pressure increases with rise and diminishes with fall of temperature. The term u dispersoids " as here used, means heterogeneous combinations of Graham's " sols " and " gels." " Isotonic solutions " are solutions of equal osmotic pressure, and true solutions give osmotic pressures in proportion to their molecular weights. (See Dialysis.) OSSEIN A variety of gelatin or albuminous substance present in and prepared from bones. (See Gelatin.) OSTEOLITE A mineral calcium phosphate (Ca 3 (PO 4 ) 2 ,2H 2 O). OTOBA BUTTER The fat expressed from the fruit of My- ristica otoba, containing glycerides and some sesquiterpenes ; saponifkation value, 185; and melting-point, 34 C. OTTO OF ROSES See Attar of Roses. OXALATES Compounds of oxalic acid with metals and bases. The alkaline oxalates are soluble in water, but the others are for the most part insoluble. OXALIC ACID OXIDATION 357 OXALIC ACID (C 2 H 2 O 4 ,2H 2 O) may be regarded as an oxi- dation product of the alcohol named ethylene glycol (C 2 H 6 O 2 ), and is dibasic. It occurs in nature combined with potassium as oxalate (K 2 C 2 O 4 ) in many plants, par- ticularly in wood- sorrel (Oxalis acetosella) and varieties of Rumex ; in the free state in some varieties of Boletus, and as calcium oxalate in rhubarb root and many lichens. Urinary deposits and calculi also often contain the calcium salt. It can be made by the action of nitric acid upon sugar, but is prepared commercially by fusing a mixture of cellulose (sawdust), with potassium and sodium hydroxides at from 200 to 220 C. in flat iron vessels. The fused mass is afterwards extracted with water, and upon addition of calcium chloride, insoluble calcium oxalate (CaC 2 O 4 ) is precipitated, and from this compound, oxalic acid is obtained by treatment with sulphuric acid. The soft woods give a better yield of oxalic acid than the hard woods. It can similarly be obtained from sugar and starch. Oxalic acid can also be prepared by heating sodium car- bonate with carbon dioxide under pressure, thus producing sodium formate (NaCHO 2 ), and when this is heated with sodium carbonate, oxalate of sodium is produced. By adding a calcium salt to the solution of sodium oxalate, calcium oxalate is precipitated, and when that compound is treated with sulphuric acid, the oxalic acid is set free. Oxalic acid is very poisonous, crystallizes in large trans- parent prisms, which slowly effloresce in the air, and is very soluble in water and to some extent in alcohol. The hydrated acid melts at 98 C. in its water of crystallization, while at 100 C. it becomes anhydrous, and at 110 to 120 C. it decomposes and yields a mixture of carbon monoxide and dioxide. Oxalic acid is used in the dyestuffs and textile industries, and for various other applications. The ferrous-potassic oxalate (FeK 2 (C 2 O 4 ) 2 ) is a powerful reducing agent, and is used in photography as " oxalate developer." OXAMIDE (C 2 H 4 N 2 O 2 or NH 2 .CO.CO.NH 2 ) A white crystal- line substance, being the normal amide of oxalic acid. OXIDASES Enzymes capable of effecting oxidation as distinct from the hydrolytic action of most enzymes. OXIDATION is a process by means of which, oxygen is either added to a substance (as in the simple case of converting mercury into its red oxide by heating it in air or oxygen) 358 OXIDATION OXYGEN OXIDATION (Continued) or made to remove hydrogen from a substance as in the case of oxidizing ethyl alcohol into aldehyde C 2 H 6 + O = C 2 H 4 + H 2 0. When the process is carried still further, oxygen is also added, acetic acid being produced C 2 H 6 O + 2 = C 2 H 4 2 + H 2 0. Combustion of organic matters and the roasting of metallic sulphides are also acts of oxidation. (See Oxidizing Agents.) OXIDES See Bases, Chemical Compounds, p. 101, and Oxygen. OXIDIZING AGENTS Chemical substances which are capable of giving up oxygen to other substances having an affinity for it, including air, oxygen, ozone, and many substances rich in oxygen, as, for example, potassium permanganate (KMnO 4 ), potassium dichromate (K 2 Cr 2 O 7 ), chromic anhydride (CrO 3 ), nitric acid (HNO 3 ), and the various per- oxides. For instance, gaseous ammonia is oxidized by chromic anhydride, which substance is reduced thereby to sesquioxide as shown in the equation (See also Oxidation.) OXIMES A series of bodies obtained from aldehydes and ketones by condensation of the carbonyl group (C:O) with the compound hydroxylamine (NH 2 .OH). OXYDASES See Oxidases. OXYGEN (O) (and its Compounds) and OZONE Oxygen (atomic weight, 16; melting-point, -218 C.) was origin- ally obtained by heating the red oxide of mercury in the concentrated rays of the sun through the medium of a powerful lens. Associated in combination with hydrogen, it exists in water (of which it makes up eight-ninths of its weight), and it has been roughly estimated to form nearly one-half by weight of the various rocks of which the earth's crust is composed. Oxygen gas is not only yielded by electrolysis of water and by heating the red oxide of mercury HgO = Hg + 0, but a number of so-called peroxides, of which manganese dioxide is typical, yield to the same heat treatment, thus : 3MnO 2 =Mn 3 O 4 OXYGEN AND OZONE 359 OXYGEN (Continued) That is to say, the manganese dioxide gives off oxygen gas, and is reduced to a lower state of oxidation when heated to redness. Barium peroxide (BaO 2 ) behaves similarly : BaO 2 =BaO-i-O. This change takes place at a temperature of 1,400 C., and when completed, the BaO can be reconverted to BaO 2 by exposing it to a current of air under pressure at the lower temperature of 700 C. It is upon the basis of these two alternate changes that Brin's method of manufacturing oxygen is based. Potassium chlorate (KC1O 3 ) when heated to a state of fusion also gives off oxygen, being reduced to the chloride (KCl). Pure oxygen gas is colourless, tasteless, and slightly soluble in water (i volume of which at o C. dissolves 0-0489 volume of the gas), fish being dependent upon this dissolved quantity for respiration. In fact, oxygen is the only gas that is capable of supporting respiration. The oxygen of the air, of which it constitutes about one- fifth, can be separated from the associated nitrogen by chemical means, and it has been found possible to reduce the air to a fluid or water-like state. This is done by pumping the air at a very low temperature and under great pressure into vessels made exceedingly cold. From liquefied air, the two gases, nitrogen and oxygen, pass again into the state of vapour at different temperatures ; so that it is possible to boil off the nitrogen or most of it before the oxygen, and this process is used for the manufacture of liquid oxygen on a large scale. Liquid air is so cold that when such materials as flesh or india-rubber are cooled in it, they become brittle and when struck with an hammer fly into pieces like glass. Oxygen is still liquid at 210, and in this form is of a pale steel-blue shade of colour and exhibits strong mag- netic properties. Pure oxygen is now an article of commerce, and is not only largely used for the treatment of certain complaints by inhalation but also for many manufacturing and trade purposes, including its employment in association with hydrogen or acetylene for the production of flames used for the cutting and welding of metals. Among other applications of liquid oxygen is that of its use as an explosive when mixed with combustible matter, 360 OXYGEN AND OZONE OXYGEN (Continued) such as sawdust or carbon. Liquefied oxygen in itself is not explosive, but cartridges of paper filled with sawdust or other combustible and soaked in the liquid oxygen for some five or ten minutes and lighted in a closed space, such as a borehole made for blasting purposes, are highly ex- plosive. A litre of oxygen used in this way is said to be the equivalent of i kg. of black gunpowder and very much cheaper. The importance of oxygen in respect of respiration and combustion is referred to elsewhere. (See Air.) Oxygen exhibits powerful and widely spread affinities for other substances, forming various oxides with a great number of elements, combining with hydrogen to form water and hydrogen dioxide, and entering into the com- position of an infinite number of chemical compounds. Ozone. When oxygen gas is subjected to the influence of the silent electric discharge, it is converted into what is called an allotropic state and becomes ozone ; the chemical differ- ence being that whereas the molecule of oxygen contains 2 atoms (O 2 ), that of ozone contains 3 atoms (O 3 ) ; and the properties of the two substances are perfectly distinct. Ozone is also produced when phosphorus is partially im- mersed in water and exposed to the air : ozone is formed in the air and hydrogen peroxide (H 2 O 2 ) is formed in the water. As prepared by the use of electrical " ozonators " it is used commercially for the bleaching of wax, textiles and other fabrics, paper pulp, sponges, and for giving drying proper- ties to oils, varnishes, and paints. Oxygen is quite tasteless and odourless, whilst ozone has a peculiar fishy odour, is soluble in turpentine, and exhibits very superior powers as an oxidizing and bleaching agent. For example, silver does not suffer oxidation when exposed to pure oxygen, but it is rapidly attacked by ozone and be- comes peroxidized. It has also the power of decomposing potassium iodide, setting iodine free. By way of absolute proof that ozone and oxygen are identical in matter, it may be stated that they are mutually convertible, ozone being retransformed into oxygen by raising it to a temperature of 246 C. 2 volumes of ozone thus yielding 3 volumes of oxygen. Ozone is often found present in small quantity in the air, and there is evidence of its presence in the upper atmo- sphere at high altitudes ; doubtless, it is formed in lightning discharges when the oxygen of the air is subjected to electrical influences. In the liquefied condition, ozone exhibits an intense blue colour and is extremely explosive. OXYGENATED WATER PAINTS 361 OXYGENATED WATER Water mechanically charged with oxygen gas and not to be confounded with hydrogen dioxide. OXYILEMOGLOBIN The compound formed in the blood by the action of inspired oxygen on its haemoglobin constituent, which carries oxygen to the animal tissues. OXYHYDROGEN FLAME Produced by burning a mixture of oxygen and hydrogen gases ; until superseded by the electric furnace it was used, amongst other purposes, for the manufacture of artificial rubies and sapphires. Its temperature is in the neighbourhood of 2,800 C. OZOKERITE A mineral wax of yellowish-black or green colour occurring in the vicinity of coal in Galicia, Moldavia, Utah, Wyoming, and elsewhere. It is in the nature of a paraffin hydrocarbon and is used in connection with the manufacture of candles, sealing-wax, paints, and other articles. Its sp. gr. is 0-85 to 0-95 ; it melts between 55 and 110 C., according to variety, and is soluble in benzol, turpentine, carbon disulphide, etc. By purification and bleaching it gives the ceresine of commerce. OZONE See Oxygen, p. 360. PAINTS Mixtures of white-lead, red-lead, zinc oxide, zinc sulphide, lime, barium sulphate, or other mineral bases with boiled linseed oil and turpentine, used to prevent the rust- ing of iron and for the preservation of wood and other surfaces ; also for artistic and decorative purposes. Tests have definitely proved that a paint made with 50 per cent, barytes and 50 per cent, white-lead is more durable as a pigment than pure white-lead paint. A luminous paint of soft greenish glow and great dura- bility is now prepared by incorporating a small proportion of radium salt in a zinc sulphide base, using some good binding material such as nitro-cellulose lacquer. Volatile liquids, such as benzene, petrol, turpentine, naphtha, and acetone, are used in paint-making as thinners or vehicles, and upon evaporation, leave the boiled linseed oil and mineral base on the coated surfaces. The linseed oil absorbs oxygen from the air, and mixed with the base forms a conglomerate solid mass constituting the real paint. Turpentine differs from the other vehicles named, inasmuch as it does not volatilize so quickly, and absorbing oxygen from the air J (particularly in warm weather and sunlight), forms a skin of oxidized product, thus adding slightly to the weight of the dry paint. (See also Enamel Paints, Lithopone, and Varnishes.) 362 PALLADIUM PALM OIL PALLADIUM (Pd) Atomic weight, 106-7; S P- g r -> II '5J melting-point, about 1,500 to 1,550 C. Palladium is a rare metal of the platinum group of elements, and is found associated in platinum ores to the extent of from J to i per cent. It is white, fairly ductile and malleable, and is especially interesting on account of its capability, particularly in the spongy condition, of "occluding" gases. If, for example, a wire of palladium be made the negative pole of a Voltaic cell, it will in course of the decomposition of water, absorb as much as 936 times its own volume of hydrogen gas, during which time it increases very largely in bulk. A piece of foil of the metal will, when heated to between 90 and 97 C. in an atmosphere of hydrogen, absorb as much as 643 times its own volume of that gas. Palladium is readily soluble in hot nitric acid, and its compounds, which resemble those of platinum in form and general characters, include three oxides (Pd 2 O, PdO, and PdO 2 ), and two chlorides (PdCl 2 and PdCl 4 ), which are soluble in water, etc. The metal can be obtained by ignition of the double palladium-ammonium chloride, and is used as an alloy with gold, silver, or copper in dentistry, also for balance wheels of watches and as a catalyst, etc. (See Occlusion.) PALM OIL (Palm Butter) is obtained by crushing the fermented fruit of the West African oil palm Rlceh guineensis and other species, including Cocos butymcea and A voira elais, while the South American oil comes from the analogous but smaller Elais melanococca. It consists of the glycerides of palmitic, stearic, and oleic acids with a large proportion of free palmitic acid, varying, it is stated, from 12 per cent, in the fresh to over 50 per cent, in old oil. It is purified by melting to remove water, and can be decolourized by chemical agencies. The sp. gr. of the West African supply is generally given as o '92 to 0*93 and the iodine value as 13*5, but a recent publication gives the following constants of the two supplies above referred to : West African. South American Noli Palm Oil. Sp.gr. 0-8586 0-8636 Solidification point ... 36-46 33-6 Saponification value ... 196-205 199 Iodine value 53~57 83-5 Palm oil is of orange-yellow colour, has the consistence of butter, and is extensively used in making margarine, soap, PALM OIL-PANCREATIC JUICE 363 PALM OIL (Continued) and candles, also in admixture with tallow and some pro- portion of alkali as railway-wagon grease. The flesh of the South American fruit contains 29 per cent, of oil, equal to 31-5 per cent, in the desiccated fruit. Palm Nut or Kernel Oil is yellowish, fat, and edible, and is obtained by crushing the kernels or extracting the oil therefrom by solvents. It consists of the glycerides of palmitic, stearic, myristic, lauric, caprylic, and caproic acids, and is practically devoid of free fatty acids. It is soluble in alcohol, carbon disulphide, and ether. Its sp. gr. is generally given as 0-952, and the iodine value as 13-5, but the communication above referred to gives the constants as follows : West African. Noli Palm Oil. Sp. gr. ... ... 0-8731 0-8651 Solidification point ... 2o-25'5 26*9 Saponification value ... 242-255 234 Iodine value ... 10-3-17-5 27-7 The kernels of the South American fruit contain 45-4 per cent, oil, equal to 48-7 per cent, in the desiccated seeds. The oil is used in soap-making, chocolate articles, and in pharmacy. Curua Palm Oil (from Attalea spectabilis) from Brazil. The dry kernels yield 65-3 per cent, of semisolid, greenish oil of sp. gr., 0-8693; refractive index, 1*447; melting-point, 23*6 C.; saponification value, 259-5; and iodine value, 8*9. PALM WAX From the palm named Ceroxylin andicola. (See Waxes.) PALMAROSA OIL See Geranium Oil. PALMITIC ACID (Ci 6 H 32 O 2 ) A constituent of most of the harder fats, including spermaceti, and especially palm oils. It is tasteless, odourless, soluble in hot alcohol and ether, and is obtained in crystals which melt at 63-4 C. It can be distilled at reduced pressure without change and when saponified with alkalies forms soaps. (See Fats.) PALMITIN See Fats. PANCREATIC JUICE A secretion of alkaline reaction, con- taining ferments (enzymes) which assist in completing the digestion of substances contained in the chyme and in emulsifying fatty bodies also present therein. When 364 PANCREATIC JUICE PARA-CRESOL PANCREATIC JUICE (Continued) agitated with neutral oils, pancreatic juice makes perfect emulsions. This emulsification enables the fatty matters to pass through the pores of the mucous membranes into the chyle ducts. In common with saliva it also has the property of converting starch into sugar. (See Enzymes.) PANCREATINE See Enzymes. " PANDERMITE "--A trade name for calcium borate, used in compounding ceramic frits. PAPAIN See Enzymes. PAPAVERINE See Opium. PAPER was made almost exclusively from rags down to 1866, but in that year esparto grass was first employed, and since then, wood pulp and straw have been very extensively used in its manufacture, as also the cellulose made from the bamboo and Savannah grasses. To prepare wood pulp, the bark is removed and after being cut up into small pieces, the wood is boiled with a mixture of bisulphite of calcium (Ca(HSO 3 ) 2 ) or magnesia and water, which renders the non- cellulose parts soluble, and thus yields from 40 to 50 per cent, of pulp consisting practically of cellulose. The bleaching of pulp is effected by means of sulphur dioxide. In Germany, yarn is now prepared on a large scale from paper. Many qualities of paper are loaded with mineral matters, such as china clay and calcium sulphate, for the purpose of filling the pores and giving a good surface, whilst for writing-paper, and some other qualities, sizing is resorted to so as to render the surface impermeable to ink. This is effected either by adding resin to the pulp and afterwards adding alum solution so as to fix it in the body of the paper, or the spun paper is passed through a bath of gelatin solution and then through one of alum solution to precipitate the gelatin in the pores of the paper. The paper is spun by streaming the pulp mixture over a wire cloth, thus forming a continuous sheet, which is afterwards pressed between hot rollers, thus drying and at the same time polishing it. (See Cellulose and Silk, Artificial.) PARA - COMPOUNDS Substitution products derived from benzene in which the substituting radicals or groups are constitutionally placed in certain definite positions in the benzene nucleus para-cresol, for instance. PARA-COUMARONE RESIN See Coumarone. PARA-CRESOL See Cresol. PARAFFIN OILPEA-NUT OIL 365 PARAFFIN OIL A general name given to a number of oily liquids heavier than kerosene, in the nature of hydrocarbons of flash-point from 300 to 450 F., variously derived from the distillation of wood, coal, lignite, peat, shale, petro- leum, etc. There are varieties of yellowish, brown, red, or green colour, used for lubricating purposes and in leather- dressing. (See Petroleum.) PARAFFINS See Hydrocarbons and Petroleum. PARAFFIN WAX See Waxes. PARAFFINUM LIQUIDUM, B.P. A pharmaceutical prepara- tion, being a mixture of hydrocarbons of the methane series, of sp. gr. 860 to 890, with a boiling-point above 360 C. ; used as an internal lubricant, also as a vehicle for oily spray solutions containing menthol, thymol, and volatile oils. PARAFORM or PARAFORMALDEHYDE, (CH,O) a , is a white substance soluble in hot water, constituting a poly- meric form of formaldehyde (CH 2 O), and when volatilized it passes back again into that form. Its disinfecting power in vaporous form is identical with that of formaldehyde. PARALDEHYDE or PARA-ALDEHYDE (C 6 H 12 O 3 ) A water- white liquid of pleasant odour, being a polymer of acetalde- hyde; used as a soporific. Sp. gr., 0-9943; and boiling- point, 124 C. PARIS GREEN (Schweinfurt Green) Copper arseno-acetate (3CuOAs 2 O 3 .Cu(C 2 H 3 O 2 ) 2 ) ; an emerald - green pigment prepared by boiling basic acetate of copper with arsenic trioxide. PASTEURIZATION The sterilization of milk by heating to a temperature of 82 C. for a few minutes. PATCHOULI OIL' Sp. gr., 0-970 to 0-995; rotation, -50 to 68. An essential oil derived from the leaves of the herb Pogostemon patchouli, indigenous in Northern India and China, and grown in the West Indies and the Straits Settle- ments. It is yellowish and somewhat thick, soluble in alcohol and ether, and used in perfumery. Its constituents include eugenol and cinnamic aldehyde. PEA-NUT OIL See Arachis Oil, p. 36. 366 PEARL ASH PEAT PEARL ASH An American crude potassium carbonate pre- pared from wood ashes by concentrating the lixiviate, until the less soluble salts have crystallized out, then evaporating the mother-liquor to dryness and calcining the residue. PEARLS are secretions of certain shell-fishes such as the pearl oyster, and consist of calcium carbonate interstratified with certain membranes resulting from chemical changes, to a contamination of which the occasional loss of lustre is probably due. The chief fisheries are in the Persian Gulf and Ceylon. (See Mother of Pearl.) PEAT A carbonaceous deposit occurring in fen and marshy areas, resulting from chemical changes affecting the mossy and other plants which abound therein, often found in beds of from some inches to many feet in thickness, and con- taining from 24 to 30 per cent, of carbon. When air- dried, it forms a valuable fuel, and when coked in ovens or distilled, it yields many valuable products allied in character to those derived from lignite and coal. It is stated that by use of the so-called electro-osmose filter, 85 parts of water can be easily removed from hydraulically mined peat con- taining only 5 parts of the dry substance in 100 parts of suspension, so that where water-power is available to produce electricity sufficiently cheap, and peat beds are near enough and thick enough, this process of drying holds out great promise. The average calorific value for Irish air-dried peat is about 6,850 B.T.U. per lb., and its ash content is 3 per cent. The nitrogen content increases from the surface (i per cent.) downwards (to 2*5 per cent, at the bottom of deep bogs), and it is calculated that it should yield about 100 Ibs. of ammonium sulphate per ton of air-dried peat. Its main uses, however, at present are as litter, cattle food, and fuel, the last named including the various distillation products. It also has value by reason of its nitrogen content as a fertilizer, the black decomposed qualities being best for such use. To be of use for carbonization, it is stated that peat must not contain more than 25 per cent, of moisture or 5 per cent, ash, and it then yields 30 per cent, gas, 5 per cent, tar, and 0-25 per cent, ammonia at a retort temperature of 1,100 C The incomplete combustion of peat in a gas-producer yields some proportion of volatile oils and wax, resembling the Montana wax of lignite, a soft pitch being left behind. The volatile oils contain a proportion of phenolic bodies of PEAT PEPPERMINT (OIL OF) 367 PEAT (Continued) an acidic character allied to those yielded by the distillation of blast furnace tar that is to say, of a higher germicidal character than ordinary coal-tar distillates. The calorific value of dry turf is said to be about half that of coal. Wet peat from an undrained bog contains about 8 per cent, dry material and 2- 8 per cent, charcoal, while a well- drained bog gives a peat of which 100 tons will yield about 3' 5 tons of charcoal. It has been estimated that in Ireland, the peat contained in the bogs amounts to more than ten times the proved coal reserves of that country. PECTOSE The pulpy part of fleshy unripe fruits, insoluble in water, and which becomes converted into pectin (which is soluble) by the agency of heat or by the ripening process. It is this last-named substance that imparts to their juices the property of gelatinizing when boiled. PEGMATITE A variety of granite rock. PELARGpNIC ACID (C 9 H 18 O 2 ) A product of the oxidation of oleic acid and contained naturally in the volatile oil of Pelargonium roseum. PENNYROYAL (HEDEOMA) OIL is distilled from the leaves and tops of Mentha pulegium, and is a pale yellowish, limpid, essential oil of mint-like odour, containing a ketonic sub- stance named pulegone (C 10 H 16 O), of which it contains about 80 per cent. ; sp. gr. is 0.93 to 0-96, and rotation + 1 3 to + 35. It is produced in Spain, Southern France, and Africa, and is used in medicine and as an insectifuge. PENTANE See Hydrocarbons, p. 250. PENTOSANS Derivatives of the hexoses, such as arabinose and xylose, present in many plants. They are removable from cotton by treatment with 5 parts of cold 17 per cent, solution of sodium hydroxide. PEPPEE OIL Extracted from common pepper (Piper nigrum) by solvents. It is yellowish, volatile, soluble in alcohol and ether, and contains phellandrene, cadinene, and dipen- tene. Its sp. gr. varies from 0*87 to 0*91, and it exhibits an optical rotation of from - 5 to + 12. PEPPERMINT (OIL OF) The essential oil obtained by dis- tilling the leaves and tops of the Mentha piperita. It contains from 45 to 90 per cent, of menthol (C 10 H 20 O), and has a sp. gr. of 0-9 to 0-92, and rotation - 22 to - 42, ac- cording to the variety. Its menthol content deposits upon cooling. There are several varieties, including English, 368 PEPPERMINT (OIL OF) PERFUMES PEPPERMINT (OIL OF) (Continued) Italian, American, Chinese, and Japanese productions. The English and American oils contain from 50 to 69 per cent, menthol, have a sp. gr. of from 0-90 to 0*91, optical rotation - 25 to 29*5, and refractive index 1*459 to 1*464. The Chinese oil is light brown in colour, of rather dis- agreeable odour and bitter taste ; its sp. gr. is 0*909, and it contains about 70*57 free menthol. The Japanese oil contains from 73 to 83 per cent, free menthol. The American oil is the best adapted for perfumery. PEPSIN The digestive ferment of gastric juice which is active only in a dilute acid environment, hydrochloric acid of from 0-08 to 0*2 per cent, strength being more favourable than lactic or acetic acid. Neutralization suspends its action. It is secreted in certain glands of the stomach and it is by its agency that albuminoids, etc., partaken as foods are rendered assimilable as peptones. The "pepsin " preparation of commerce is obtained from the glandular layer of pigs' or calves' stomachs. Pepsin is a nearly white amorphous substance, insoluble in alcohol, but very soluble in dilute acids and glycerine. Its solutions are coagulated by boiling, and it then loses its digestive power. It is sometimes used as a substitute for rennet. PEPTONES result from the enzyme action of pepsin in the juices of the stomach upon the albuminous matters par- taken of as food. They are soluble in water, diffuse readily through vegetable parchment and are not coagulated upon heating, so that they are in the best state for assimilation in the human economy. PERBORATE OF SODIUM See Sodium Compounds. PERBORIN Perborate of sodium. PERCHLO RATES See Chlorine Compounds, p. 112. PERCOLATE To filter or pass through, as, when making drinking- coffee, the dry coffee is percolated by hot water. PERFUMES Preparations of a volatile nature consisting for the most part of odoriferous substances dissolved in alcohol. Some of the better known perfumes are obtained by distilling the flowers or flower-petals of plants with wa ter attar of roses, for example while others are ex- tracted therefrom by means of solvents such as light petroleum spirit or alcohol, the solvent being afterwards evaporated by distillation in a vacuum. Yet others, such as the tuberose and jonquil, the delicacy of which may be PERFUMES 369 PEEFUMES (Continued) impaired by the distillation process or solvent action, are obtained by " enfleurage " a method which consists in pressing the flowers against a layer of cold fat, such as lard or petroleum jelly spread over glass plates, or by drawing warm, moist air through the flowers and passing the current charged with the odoriferous principles over fatty layers, from which the perfume is subsequently ex- tracted by strong alcohol. The subsequent evaporation of the alcohol yields the " quintessences " as residual products. Ethyl butyrate is the odoriferous constituent of the pine- apple ; the pear owes its fragrance to amyl acetate, and the apple to the amyl esters of formic, acetic, and hexoic acids. Coumarin, to which the Tonquin bean owes its fragrance, is now made artificially ; so also vanillin, which gives its pleasant odour to the vanilla pod and is now largely made from eugenol (the chief constituent of oil of cloves). An artificial essence of violets named ionone is made from citral (to which the odour of lemons and lemon grass is due), and there are many synthetically prepared perfumes, as distinct from those derived from flowers, or made in imitation of natural products, as, for example, so-called " heliotropin," sold as " white heliotrope." So, again, a ketonic substance named irone is a fragrant oil made from the root of iris (orris), having the odour of the violet. Among the new synthetic perfumes, may be mentioned " fragasol," which is the butyl ether of beta-naphthol, analogous to yara-yara and neroline, which are the methyl and ethyl ethers respectively. " Benzilisoeugenol " has a fine carnation odour, and " rhodinol," or rose-aldehyde, is probably a mixture of aldehydes used in the manufacture of artificial attar of roses. Stysolyl acetate has the perfume of the calyx of the rose, and amyl benzyloxide, which has a marked gardenia odour, is used for perfuming soaps, a trace of methyl para-cresol improving it. Some of the essential oils constituting the bases of per- fumes and essences, are obtained by pressure of the fruit rinds containing them, as, for example, the orange, lemon, and bergamot oils ; and many others such as eucalyptus oil, camphor oil, and the terpenes are commercially avail- able in large quantities, and used either alone or in com- bination with other extractives in compounding various perfumes. 24 370 PERFUMES" PERMUTIT " PERFUMES (Continued) Apart from the essential oils used in making perfumes and soaps, large quantities are used in compounding such drinks as lemonade and sundry alcoholic liqueurs, and for flavouring purposes, in cooking and confectionery, and in medicine, so that the trade in these oils, and the perfumes made from them, is one of large dimensions and importance. (See also Odour Theory.) PERICLASE A native magnesium oxide (MgO). PERILLA OIL An essential oil from the seeds of Perilla ocimoides. The yield is from 33 to 35 per cent., the oil being of a greenish -yellow or brownish colour. It has a sp. gr. 0-932 to 0-945, saponification value about 192, iodine value 187 to 202, and refractive index 1-484. It is soluble in alcohol and ether, and is used as a substitute for linseed oil in making varnishes, and to some extent as an edible oil in Japan and China. The oil from P. nankinensis is stated to result from the decomposition of a glucoside in the leaves, and to contain 20 to 30 per cent, limonene, 44 to 57 per cent, perillic aldehyde, and some pinene. PERIODIC LAW See Elements. PERMANENT WHITE See Barium, p. 49. PERMANGANATES See Manganese, p. 306. PERNAMBUCO (Lima wood) A red wood from Ccesalpinia bijuga, which yields a red dye extract. " PERMUTIT " A number of preparations, called " permutits," are artificially produced silicates, capable of exchanging their basic constituents when placed in certain solutions; so that when employed for softening water an exchange takes place, the soda of the " permutit " passing into the water and being replaced by the lime and magnesia (the hardening constituents) of the water. The general method of preparation consists in melting china clay (kaolin) with quartz and sodium carbonate, and washing with water, the product being a double silicate of soda and alumina, containing about 46 per cent, of SiO 2 , 22 per cent, of A1 2 O 3 , 13-6 per cent. Na 2 O, and 18-4 per cent. H 2 O. The permutit is revivified by passing a fairly strong solution of common salt through it, which restores it to its original constitution, so that after washing it with water, it can be used again for softening further quantities of hard water. PEROXIDES PETROLEUM 371 PEROXIDE This term indicates an oxide of higher degree than the ordinary oxide; for example, barium oxide (BaO) is the ordinary barium oxide, whereas the peroxide (dioxide) is BaO 2 . There are some organic peroxides, among which may be mentioned acetyl peroxide, (C 2 H 3 O) 2 O 2 (an explosive body prepared from acetic anhydride by the action of barium dioxide) ; ethyl hydrogen peroxide, C 2 H 6 O 2 , and acetone peroxide, (C 3 H 6 O 2 ) 2 , both of which are more or less un- stable, and are made by the agency of hydrogen peroxide in presence of potassium hydroxide. PEROXIDE OP HYDROGEN See Hydrogen, p. 253. PEROXIDE OF SODIUM See Sodium Compounds. PERRY Fermented juice of pears. PERSIAN BARK See Cascara Sagrada. PERU BALSAM See Balsams. PERUVIAN BARK See Quinine. PETALITE A native silicate of aluminium and lithium. PETIT-GRAIN OIL Distilled from the leaves and unripe fruit of Citrus bigaradia, resembling neroli oil. It is yellow- ish in colour, is soluble in alcohol and ether, has a sp. gr. of from 0-89 to 0-90, and is used in perfumery. PETROL Fractional distillates from petroleum, or "cracked" petroleum products, with or without admixture with benzol, ranging in boiling-point from 50 to 200 C. The better qualities of petrol are used in common with gasoline for pro- ducing "air-gas" for illumination purposes. (See Gasoline.) PETROLATUM Petroleum jelly ; vaseline. PETROLEUM (rock or mineral oil) is a natural, dark-coloured, oil-like deposit of hydrocarbon character, sometimes occur- ring in beds or lakes, as in Trinidad, and at other times flowing from clefts of rocks or from deep wells, as in the northern parts of the United States, particularly between Pittsburg and Lake Erie. Deposits also occur in parts of Germany, Persia, Roumania, Galicia, Burmah, the Crimea, and have been recently discovered at Hardstoft in Derby- shire, also in Norfolk and Nottinghamshire. The petroleum from all fields consists in the main of so- called paraffin hydrocarbons, associated with small pro- portions of compounds containing oxygen, nitrogen, and sulphur, and are worked on a large scale as the source of a number of valuable products. The hydrocarbons of many of the natural petroleums are of the same series, although contained in varying proper- 372 PETROLEUM PETROLEUM (Continued) tions ; but while the American oils consist in the main of paraffin hydrocarbons, the Russian oil con tains large amounts of the general formula C W H 2 (such as C 6 H 12 , C 7 H 14 , etc.), known as naphthenes, which are isomeric with the olefines. The oil recently discovered, and now being produced, at Hardstoft, in this country, contains naphthenes, and an early sample furnished upon examination 7 per cent, motor spirit, 40 per cent, burning oil, 20 per cent, gas oil, 30 per cent, lubricating oil, and 3 per cent, solid paraffin. Crude petroleum, which is used to some extent as a sub- stitute for coal in locomotives, has a sp. gr. ranging from 078 to 0-97 or more, and by fractional distillation yields a number of products, including the so-called petroleum ether, benzine, gasoline, kerosene, paraffin oil, heavy lubricating oils, and petroleum jelly, which are described under their respective names. The various fractional distillates are further separated and refined by redistillation. The benzine produced from many crude petroleums re- quires no chemical treatment, and is largely used as motor spirit; but the " white spirit " and " kerosene " which follow (and are used in lamps) are refined by filtration through powdered bauxite or fuller's earth, which removes the sulphur compounds and can be regenerated for further use by heating. Paraffin wax is separated from the higher distillate portion containing it, by cooling to 45 F., and squeezing out the heavy associated oil, which is utilized as lubricating oil after redistillation. Coke or pitch is finally left in the retort, and, the former being very pure, finds a ready sale to the manufacturers of electric light carbons and carbon crucibles, whilst the pitch can be used either as fuel or can be oxidized or sulphurized, and thus utilized in making artificial asphalt. When petroleum oils are "cracked" at about 700 to 750 C., most of them yield a distillate containing toluol, and large supplies of that material were thus obtained during the Great War, and supplies of so-called motor spirit are made by "cracking" the heavier oils. Fatty acids can be obtained from petroleum hydro- carbons by catalytic oxidation, using air or oxygen in association with certain lead or mercuric compounds (which apparently dissolve in the products of the process) at a temperature of 115 to 120 C., and under a pressure of three atmospheres, with agitation in the presence of water for some seven hours. The oxidation products have been stated at from 7 to 20 per cent, water, 25 to 40 per PETROLEUM PHELLANDRENE 373 PETROLEUM (Continued) cent, lower fatty acids, with small amounts of aliphatic aldehydes and ketones, from 50 to 78 per cent, of higher fatty acids, and 10 to 15 per cent, of unsaponifiable matters. The products are fractionated by distillation, and the higher fatty acids thus obtained mixed with 10 to 20 per cent, of tallow or cocoa-nut oil fatty acids to make soap. Fatty acids can also be obtained by the chlorination of certain paraffin hydrocarbons at 160 C., subsequent elimination of the hydrogen chloride thus produced, and oxidation of the resulting olefine by means of potassium permanganate or ozone. American petroleum (U.S.A.) is said to yield on average the following fractions upon distillation : light naphtha 1 7, kerosene 50 to 54, lubricating oil 17, paraffin wax 2, and loss 10. Petroleum is commonly supposed to be derived from organic matters by chemical changes operating over long periods of time, and as all petroleums contain so-called algae wax, one theory favours enormous masses of algae accumulated over immense periods of time in marshy areas as its material origin. The total output of petroleum in 1920 was over 97 million tons, and of this the British Empire controlled only 4 per cent. PETROLEUM ETHER The fractional distillate from petro- leum, which boils at from 40 to 70 C., and of sp. gr. 0-635 t 0*660, purified by washing with sulphuric acid, then with soda, and subsequent redistillation, and used as a volatile solvent. It contains a large proportion of the lower paraffin hydrocarbons (heptane, hexane, etc.). PETROLEUM JELLY is an emulsion of soft paraffins dis- persed in heavy oils, the viscosity of which increases gradually with decreasing temperature until the " gel " state is reached. There is no separation of crystalline wax, which is only obtained upon distillation of the jelly, in the distillate. It is made from the still residue left after the distillation of petroleum, being subsequently decolourized by filtration in a heated state through fuller's earth or animal charcoal, and is used as a lubricant, leather grease, in making polishes, as a rust preventive, and as a perfume extractor in enfleur- age. (See Petroleum.) PEWTER See Tin. PHELLANDRENE A terpene constituent of eucalyptus oil, which boils at 171 C. (See Essential Oils and Terpenes.) 374 PHENA CETINE PHENOLS PHENACETINE (C 10 H 13 O 2 N) A colourless crystalline com- pound (acetophenetidine), soluble in water, alcohol, and ether; used as a remedy for neuralgia; melting-point, 135 C. PHENACITE Glucinum(orberyllium)ortho-silicate(Gl 2 SiO 4 ), found in Colorado. PHENANTHRENE A substance isomeric with anthracene, which it accompanies in coal tar. It melts at 99 C., boils at 340 C., and is used in making blacks. PHENAZONE See Antipyrine. PHENOLOIDS The more active principles of so-called " high- boiling acids " of phenolic and cresolic character, obtained in the redistillation of tar from blast furnaces and coke ovens. The exact constitution of the higher phenols is largely a matter of speculation, but they exhibit relatively high boiling-points as compared with the cresols, being found in the residue obtained after separation of the cresols by fractional distillation ; but it is believed that they consist chiefly of xylenols or dimethylhydroxybenzenes (C 6 H 3 (CH 3 ) 2 OH). They exhibit greater bactericidal pro- perties than the cresols, and are less poisonous than phenol. Phenoloids are used not only in making disinfectants, sheep dips, larvicides, and weed-killers, but also in making cutting compounds for engineering purposes, as they form good emulsions in aqueous soap solutions. PHENOLPHTHALEIN (Dihydroxy - diphenyl - phthalide, (C 6 H 4 OH) 3 .CO.C 6 H 4 CO) A creamy-white organic pow- der used as a purgative, as a dye base, and as an indi- cator (like litmus) in chemical reactions. A solution of | per cent, in equal parts of alcohol and water gives a strong pink colour when rendered alkaline ; melting-point, 250 C. (See Volumetric Analyses.) PHENOLS A series of bodies, some being liquids and some solids, many of which have antiseptic properties. Ordinary phenol or carbolic acid (C 6 H 6 O) is the active principle of crude carbolic acid as obtained from coal-tar distillation. In the pure state it is a white, poisonous, deliquescent, crystalline substance, of sp. gr. 1*08, which melts at 42 C.; is soluble in water (i : 15) at 16 C., and readily soluble in alcohol. It is used in the preparation of antiseptics, disinfectants, dyes, and explosives. Other phenolic bodies are cresol (C r H 8 O), xylenol (C 8 H 10 O), cumenol (C^H^O), carvacrol (C 10 H 14 O), and thymol (C 10 H 14 O). (See also Carbolic Acid.) PHENYL PHOSPHOR US 375 PHENYL (C 6 H 5 ) The benzene nucleus or radical, as, for example, in phenol (C 6 H 5 HO). PHENYLAMINE (C 6 H 5 NH 2 ) See Aniline. PHLORIDZIN (C 21 H 24 O 10 ) A glucoside found in the root-bark of some fruit" trees (such as the apple, pear, plum, and cherry), which upon hydrolysis yields phloretin (C 15 H 14 O 5 ) and grape sugar. It is soluble in alcohol and hot water. PHOSGENE See Carbonyl Chloride. PHOSPHATE ROCK See Coprolites and Phosphorus. PHOSPHATES See Phosphorus. PHOSPHATIC; MANURES See Fertilizers, Superphosphate of Lime, and Slag. PHOSPHIDES See Phosphorus. PHOSPHINE See Phosphorus. PHOSPHINES (Organic) Feebly basic compounds prepared from phosphoretted hydrogen (phosphine) (PH 3 ) by the substitution of hydrogen with alkyl radicals for example, triethyl phosphine P(C 2 H 5 ) 3 . They correspond closely to the amines in composition. PHOSPHITES See Phosphorus. PHOSPHOR BRONZE An alloy with a low coefficient of friction, used as a substitute for bronze and gun-metal in gearings, bearings, wire ropes, etc., composed of copper and tin fluxed with a variable quantity (up to i per cent.) of phosphorus, which is generally added in the form of copper phosphide or tin phosphide. PHOSPHORETTED HYDROGEN or PHOSPHINE See Phos- phorus, p. 377. PHOSPHORIC ACID See Phosphorus. PHOSPHORITE (Rock Phosphate of Calcium) A variety of apatite. PHOSPHORUS (P) and its Compounds Atomic weight, 31 ; melting-point, 44 C. This element does not occur in nature in its free state, but abounds in combination with calcium and oxygen in the seeds of plants and in soils, its presence in the latter being derived from the disintegration of rocks. Plants require phosphates as an essential to their proper growth and development, and the animal kingdom obtains its supply in turn from vegetable life. Phosphorus in various combinations is also present in many of the animal tissues, including brain matter, and the bones owe their rigidity to calcium phosphate, which makes up 60 per cent, of their substance. Bone ash, indeed, consisting as 376 PHOSPHORUS PHOSPHORUS (Continued] - it does, in the main, of that substance, is one of the chief sources of phosphorus. (See Bones.) In various com- binations as phosphate, it is present in the minerals sombrerite (Ca 3 (PO 4 ) 2 ). apatite (3Ca 3 (PO 4 ) 2 ,CaF 2 ), wavellite (2A1 2 (PO 4 ) 2 ,A1 2 (HO) 6 ,9H 2 O), and in coprolites. (See Co- prolites.) Phosphorus is made from bone ash or sombrerite by treatment with sulphuric acid of sp. gr. about 1*5, when the following interaction takes place : Ca 3 (PO 4 ) 2 + 3H 2 SO 4 = 3CaSO 4 + 2H 3 PO 4 that is to say, insoluble calcium sulphate and phosphoric acid (in solution) are produced, and after filtration of the mixture, the liquid nitrate is concentrated by evaporation and yields the acid in crystalline form of a deliquescent nature. From the acid so prepared, phosphorus may be obtained by mixing it with powdered charcoal, heating, and subsequent distillation ; at first, the phosphoric acid is broken up into water and meta-phosphoric acid as follows : H 3 P0 4 =H 2 + HP0 3 , and at a later stage there is a further change by which this acid is decomposed as expressed in the equation : 4HPO 3 + i2C = I2CO (carbon monoxide) + 2H 2 (hydrogen) + 4? (phosphorus), the phosphorus being condensed in dark yellow drops under water, in which it subsequently solidifies. In the pure state, phosphorus is a slightly yellowish- white, semi-transparent, and wax-like substance which takes fire when warmed and exposed to the air, so that it has to be kept submerged in water. In its ordinary form it is very poisonous. It has a sp. gr. of 1*83, and is soluble in carbon disulphide (CS 2 ) from which it may be obtained upon evaporation, in the form of colourless crystals. It may also be sublimated in vacuo and obtained in beautiful crystals. Phosphorus forms many compounds, and, in the form of soluble phosphates, phosphoric acid enters into the com- position of many medicines, such as chemical foods and nerve stimulants. They are also used in the dyeing and bleaching trades, the fireproofing of woods, and in sugar- refining. PHOSPHORUS 377 PHOSPHORUS (Continued) The natural phosphates, with or without treatment, are largely used in agriculture as fertilizers. Phosphorus is allotropic that is to say, it can be made to assume more than one form. When heated to between 240 and 250 C. out of contact with the air, it passes into a red form, which has a sp. gr. of 2-3, and, unlike the ordinary yellow phosphorus, is not luminous in the dark, is not poisonous, and is largely used in connection with the use of matches. These are tipped with a mixture of potas- sium chlorate, potassium dichromate, red-lead, and antimony sulphide, and when rubbed over a surface of red phosphorus and antimony sulphide (as spread over the sides of the safety-match boxes), take fire by friction. In the preparation of paraffin matches, the yellow phosphorus is employed. Phosphorus is also used in the preparation of rat-poison and in the manufacture of phosphor bronze. Phosphorus forms several compounds with hydrogen, the better known of which is hydrogen phosphide (PH 3 ) also known as phosphine. It is formed when red phos- phorus is gently heated in a current of hydrogen gas, and is also produced by the action of water upon calcium phosphide 3Ca 2 P 2 + i2H 2 O = 6CaH 2 O 2 + 4PH 3 + 2P. It is a colourless, highly poisonous gas, soluble in alcohol and ether, of offensive garlic-like odour, and takes fire at a temperature below that of boiling water. Calcium phosphide is employed in the construction of drain-testers, and the action of water upon that substance finds practical employment also in the marine appliance known as Holmes's signal. In the case of the drain-testers it is the distinctive odour of the gas that enables the operator to detect leakages in drains, whilst in the case of Holmes's signal, the phosphoretted hydrogen ignites and burns, giving a considerable illumination. Hypophosphorous Acid (H 3 PO 2 ) is a crystalline body which melts at 17*4 C., and is obtained by decomposing its barium salt with sulphuric acid, the barium compound in its turn being prepared by boiling phosphorus in a solution of barium hydroxide. Phosphoric Acid (ortho-phosphoric acid, H 3 PO 4 ), prepared as already described (p. 376), is put up in various forms viz., as a liquid of sp. gr. 1*5, also in paste containing from 40 to 50 per cent., and in crystalline form with a melting- 378 PHOSPHORUS COMPOUNDS PHOSPHORUS (Continued) point of 38-6 C. Its salts are obtained by neutralization with alkali to the required point and crystallization. It finds employment in the sugar industry, etc. There is a pyrolitic method of producing phosphoric acid viz., by smelting mixtures of phosphate rock, sand, and coke, and collecting the fumes of the generated acid by means of the Cottrell precipitator. (See Cottrell Pre- cipitating Plant.) This process is stated to be of promising character, and likely to prove much less costly than the sulphuric acid process. Phosphorous Acid (H 3 PO 3 ) is a white crystalline body with a melting-point of 70-1 C., formed by dissolving phosphorus oxide in water or by the action of water upon phosphorus trichloride PC1 3 + 3H 2 O = 3HC1 + H 3 P0 3 . It is dibasic and forms two classes of salts. Meta-phosphoric Acid (Glacial Phosphoric Acid, HPO 3 ) is a highly deliquescent glacial mass, which results from the deliquescence of phosphorus pentoxide, and can be obtained by heating ortho-phosphoric acid to redness, by which it loses a molecule of water : H 3 PO 4 -H 2 O=HPO 3 . It is used in pharmacy and medicine. Pyrophosphoric Acid (H 4 P 2 O 7 ) is a white crystalline body, soluble in water, which can be prepared in a number of ways, as, for example, by heating the ortho-acid to 213 C., when it loses a molecule of water, yielding the pyro-acid 2 H 3 P0 4 -H 2 = H 4 P 2 7 . All these acids form a number of salts, many of which are used in the arts and manufactures. There are a number of oxides of phosphorus, of which the more important are the trioxide and the pentoxide. Phosphorus Trioxide (P 4 O 6 ) is formed by burning phos- phorus in a limited current of dry air, and is a white, non- crystalline powder which melts at 22-5 C. Phosphorus Pentoxide (P 2 O 5 ) is formed when phosphorus is burned in excess of air or oxygen, and is a white powder which is volatile and may be sublimed. It is used chemic- ally as a dehydrating agent, having a great affinity for water. PHOSPHOR USPILOCA RPINE 379 PHOSPHORUS (Continued) Phospho-molybdic Acid (H 3 PO 4 ,i2MoO 3 ) A yellow, crystalline substance soluble in water, used chemically as a reagent in the examination of alkaloids. Phosphorus Trichloride (PC1 3 ) is a colourless, fuming liquid, and the pentachloride (PC1 5 ) is a yellow, crystalline body, both of which are made by the action of chlorine upon phosphorus, and are used as chlorinating agents in organic chemistry. Both are soluble in carbon disulphide. Other compounds of phosphorus include phosphonium chloride (PH 4 C1), phosphonium bromide (PH 4 Br), phos- phonium iodide (PH 4 I) (all of which are crystalline bodies), and two fluorides (PF 3 and PF 5 ). PHOTO GEN A name sometimes given to the light hydro- carbon oils (obtained from the distillation of coal, peat, and shale at low temperatures) which are used for burning in lamps. PHOTOGRAPHY See Light, p. 294. PHTHALIC ACID (C 8 H 6 O 4 or C 6 H 4 (C9 2 H) 2 ) A colourless crystalline substance, readily soluble in water, alcohol, and ether, which is made commercially by oxidizing naphthalene with fuming sulphuric acid in the presence of a small quantity of mercury at 220 to 230 C. It melts at 213 C. PICOLINE (C 5 H 4 N(CH 3 )) One of several homologues of pyridine. PICRICACID(C 6 H 2 (NO 2 ) 3 OH)(Tri-nitro-phenol) Apoisonous, lemon-coloured, crystalline substance which melts at 122 C. and is largely used in the manufacture of explo- sives and as a yellow dye for silk and wool. It is prepared by the graduated action of strong nitric acid upon phenol and by the nitration of monochlorobenzol in the presence of sulphuric acid, etc. It explodes with violence when heated or struck, is soluble in alcohol, and sparingly soluble in water, to which it gives a deep yellow colour; melting-point, 122 C. (See Explosives, p. 190.) PIGMENTS Insoluble coloured substances used as bases in compounding paints. The term is more particularly applied to mineral bases as distinct from organic colouring matters such as dyes or stains which are soluble in the vehicles used. PILOCARPINE (C U H 16 N 2 2 or C 23 H 34 N 4 O 4 ) A crystalline, poisonous alkaloid (melting-point, 34 C.), soluble in water and alcohol, contained in the leaves and stalks of jaborandi 380 PILOCARPINE PINE-TAR OIL PILOCARPINE (Continued) (Pilocarpus pennatifolius) ; used in medicine an d compound- ing hair tonics. PIMARIC ACID (C 20 H ?0 O 2 ) A substance obtained from galipot resin, resembling abietic acid, and of melting-point 144 to 146 C. PIMELITE Native green nickeliferous silicates. PIMENTO OIL A colourless or slightly yellow, heavy, volatile oil distilled from the unripe fruit of Myrtus pimenta of the West Indies, resembling oil of cloves in odour. Sp. gr., 1-045 to I<0 555 soluble in alcohol and ether; and used in perfumery and for flavouring. The oil distilled from the leaves of the plant yield about i '8 per cent, of eugenol, from which vanillin can be obtained. " PINACYANOL " A dyestuff that sensitizes photographic plates far into the red region of the spectrum. " PINAVERDOL " An isocyanine dyestuff used for sensitizing photographic plates through the green and well into the red region of the spectrum. PINCHBECK An alloy gold-like in appearance consisting of copper alloyed with zinc in varying proportions about 3 oz. zinc to i Ib. copper or i part zinc and 8 parts copper. PINE OIL This name is now Variously used, but was origin- ally applied to the turpentine-like oils obtained from pine and fir trees, particularly those from the seeds and needles. They vary in their characters, such as their odours, drying properties, and rotatory powers, etc. The oil from Pinus pumilio needles is used in medicine and is one of the best known of this class, having an agreeable balsamic odour, of sp. gr. 0-86^ to 0-875, an ^ rotation - 6 to - 14. Pine oil is a name now given in commerce also to a crude kind of turpentine obtained from the United States, and to a refined rosin oil obtained as a product of the destructive distillation of rosin. PINENE (Australene) (C 10 H 16 ) A terpene constituent of American turpentine, pine oil, and some other essential oils. Sp. gr., 0-8587; boiling-point, 156 C. PINE-TAR OIL is a distillate of pine tar which darkens to a reddish-brown colour on keeping. It has a strong tarry and sharp odour, and is a very complex mixture resulting from the destructive distillation of the tar. Its average sp. gr. is 0*970 ; it is soluble in turpentine, and is used in ore concentration by the flotation process. PIPECLAY PITCH 381 PIPECLAY A peculiar variety of clay found in Dorsetshire and Devonshire, used for making tobacco pipes and certain kinds of pottery. PIPER (Piper Nigrum) Black pepper, which yields an essential oil containing terpenes. (See Pepper Oil. p. 367.) PIPERIDINE (C 5 H n N) A colourless, liquid amine, smelling something like pepper and of basic character, found i in pepper in association with piperic acid (C ]2 H 10 O 4 ) as the alkaloid piperine (C 18 H 18 NO 3 ). It boils at 106 C, is soluble in water and alcohol, and yields crystalline salts. PIPERINE See Piperidine. PIPERITONE A ketonic constituent of eucalyptus oil yielded by the Eucalyptus piperita and E. dives, and from which, both menthol and thymol can be prepared by processes of reduction. PIPERONAL (Artificial Heliotrope) See Heliotropine. PIPETTES, as held in a pipette stand, are shown in the illustration. . They are glass tubes, with or without bulbs, used for transferring given measures of liquid from one vessel to another, and are made to hold definite quantities, such as 5 c.c., 10 c.c., 20 c.c., 25 c.c., 50 ex., and 100 c.c., being graduated on the stem. In practice, they are filled up somewhat above the graduated mark, by dipping the lower end in the liquid and sucking up with the mouth; then rapidly placing the finger (preferably moistened) on the top of the upper end, to close same after the liquid has, by release, reached the marking on the stem. PITCH is a generic name applied to a number of products more or less identical in character but variously produced. Gas-Tar Pitch or Coal-Tar Pitch is the residue left in the retorts from the distillation of gas tar, and finds use in roofing, as a binding material in the making of briquettes and joining up wooden road-paving blocks, also in making a black, coarse varnish, etc. Rosin Pitch is that left behind from the destructive dis- tillation of rosin, and can be used for the same purposes. There are also varieties of pitch left behind from the distillation of wood and petroleum oils. 382 PITCH PLANT COLOURING MATTERS PITCH (Continued)- Burgundy Pitch is used in medicine, and is the melted resin of Abietes resina, but is not a " pitch" in the same sense. (See Burgundy Pitch.) PITCH-BLENDE (Uraninite) A native uranium oxide associ- ated with other uranium compounds found at St. Stephen's, Cornwall, and in Austria, Colorado, and elsewhere. It is used as the chief source of radium and uranium compounds. PLANT (Chemical) See Chemical Plant. PLANT COLOURING MATTERS occur in the forms of so- called "plastid pigments," such as chlorophyll, carotin, etc. (which are intimately associated with the organized proto- plasmic structure of plants), and the soluble " sap pig- ments," the latter class being divisible into two main classes viz., (i) derivatives of flavone (flavonal) some- times named anthoxanthenes which are pale yellow or colourless when in faintly acid solution, but bright yellow in alkaline solution, and (2) the anthocyans, which are red in acid solution, violet when neutral, and varying from dull red or reddish-brown to purple and blue when present in the form of alkaline salts in solution. Carotin (carrotene) is according to one investigator a hydrocarbon of the composition C 40 H 56 , which crystallizes in copper-coloured leaflets, absorbs oxygen readily from the air, and becomes converted into a colourless product. It would appear from chemical investigations that, the anthocyan pigments are reduction products of the yellow sap pigment, whilst botanical work points to the conclusion that these anthocyan pigments are present in plant life in positions that are known as the seat of oxidizing influences. The anthocyan pigment of the pelargonium has been obtained in a crystalline condition, and many of these pigments occur naturally in plants in the form of gluco- sides. The anthocyans (anthocyanins) are said to contain similar nuclei, no matter how much they differ in colour, and the wide variation of tints is ascribed to slight differ- ences in constitution which leave the main skeleton intact. The blue cornflower yields a pigment identical with that of the red rose, named cyanin, which gives a chloride of the composition C 27 H 31 O 16 C1, and upon heating this substance with a 20 per cent, solution of hydrochloric acid, it is hydrolized into cyanidin and glucose : C 87 H 81 16 C1 + 2 H,0 = C U H U O.C1 + 2C 6 H U 6 . PLANT COLOURING MATTERS PLATINUM 383 PLANT COLOURING MATTERS (Continued) The anthocyanin of Salvia coccinea is named salvianin, and upon hydrolysis yields pelargonidin, dextrose, and malonic acid. The red pigment of the young leaves of the grape-vine is said to be a free anthocyanidin, probably identical with oenidin, the anthocyanidin of the purple grape (Vitis vinifera}, although it may appear in a colourless modifica- tion termed a leuco-anthocyanin, in which it appears to be associated with another substance, possibly a carbohydrate, giving rise to anthocyanidin on treatment with strong acids. Many of the yellow sap pigments were largely used in the past as mordant dyes before the synthetic colours became available in industry, and some of them, such as fustic, are still employed. The archil or cudbear group constitutes a class of colours that were also formerly of much commercial importance, and are produced from soluble colourless substances which are contained in a variety of lichens. (See also Archil, Alizarine, Chlorophyll, and Flavone.) PLANT LIFE See Vegetation. "PLASMON" A proprietary preparation of milk casein made soluble by agency of alkalies. PLASTER OF PARIS See Calcium Compounds, p. 75. PLASTICITY Capability of change; easily moulded into desired form. PLATINUM (Ft) and its Compounds Atomic weight, 195; sp. gr., 21*5; melting-point, 1,755 C. Platinum is found naturally in the metallic state in small grains and nuggets in river sand and alluvial deposits in Brazil, Borneo, California, Colombia, New South Wales, Tasmania, and the Ural Mountains; also as sperrylite, etc., in association with some other rare metals including palladium, rhodium, ruthenium, osmium, and iridium. Up to 1914 Russia supplied over 90 per cent, of the world's supply of platinum. It is of a bright greyish-white colour, is malleable and ductile, does not tarnish in the air, is heavier than gold, and is of low electric conductivity. It can be melted by the oxy- hydrogen flame. To obtain platinum from associated metals, it is digested in aqua regia under some pressure, the solution evaporated to dryness and the residue heated to 125 C. In this way, any rhodium chloride is rendered insoluble, and upon 384 PLATINUM PLATINUM (Continued) extraction with water, acidification of the extract with hydrochloric acid and addition of ammonium chloride, the red double ammonium and platinum chloride (2NH 4 C1, PtCl 4 ) is produced and crystallized out ; the corresponding iridium salt, so far as it is present, being left in the mother -liquor. From this, spongy platinum is obtained upon ignition, and may be hammered into a concrete mass or melted in the oxyhydrogen flame. The form of platinum known as "spongy platinum" is obtained by igniting the compound ammonium platinic chloride as noted above ; and " platinum black " is a soft black powder which results from the precipitation of platinum solutions by means of reducing agents. In both of these forms, the metal exhibits the property of condens- ing gases on its surface in a high degree, and a mere fragment of the spongy metal when introduced into a mixture of hydrogen and oxygen gases in the proper pro- portions, at once causes its explosion and formation of water. Even when cold, platinum has the property of condensing oxygen on its surface, and in the forms already described and in that of gauze, the metal is used as a catalyst for example, in the combustion of ammonia to nitrogen oxides and nitric acid. This catalytic action is easily interfered with by traces of many substances, phos- phine being one of such " poisons," as they are termed. Platinum alloys with many metals and the introduction of 10 per cent, iridium produces a combination which is even more resistant to chemical action than the pure metal. There are two oxides insoluble in water viz., the platinous and the platinic (PtO and PtO 2 ), both blackish powders, and corresponding hydroxides (Pt(HO) 2 and Pt(HO) 4 ), the latter of which when dried and heated sufficiently, is decomposed, leaving the metal in the free state. There are two chlorides (viz., PtCl 2 and PtCl 4 ), the first of which is a green powder insoluble in water, whilst the latter (obtained by dissolving platinum in aqua regia) is a yellowish-red crystalline salt soluble in water. The former compound is used to some extent in the platinotype photographic process. Two sulphides (PtS and PtS 2 ) are known, both of which are black and insoluble in water. Platinous chloride combines with some other chlorides to form compound salts, such as potassium platinous chloride (2KCl,PtCl 2 ) and ammonium platinous chloride (2NH 4 C1, PtCl 8 ), which is used in photography ; and the cyanide PLATINUM 385 PLATINUM (Continued) (Pt(CN) 2 ) combines with other cyanides to form double compounds known as platino-cyanides for example, potas- sium platino-cyanide (2KCN,Pt(CN) 2 ). In combination with ammonia, platinous chloride forms several remarkable compounds known as ammoniacal pla- tinum bases or platinamines, which behave as bases and form a corresponding series of salts. They may be regarded as ammonia in which hydrogen is partly replaced by a platinum compound, one of these compounds having the composition 2NH 2 ,PtCl 2 . In chemical industry, platinum is largely used as a cata- lyst, also for making stills for the concentration of sulphuric acid, and in the electro-chemical industry, and in jewellery. An alloy used by jewellers, consists of i part platinum, i part copper, and 2 to 5 parts silver. " Platinor " consists of 2 parts platinum, 5 parts copper, i part silver, and i part nickel. One form of so-called " mockgold " consists of 7 parts platinum and 16 parts copper. Platinum bronze is made of i part platinum, 90 parts nickel, and 9 parts tin ; whilst one variety of dentist's alloy is made of 5 parts platinum, 3 parts gold, and 4 parts palladium. In the forms of crucibles, dishes, foil, spatulas, weights, wire, etc., it is largely used in laboratories on account of its refractory nature that is, its capability of withstand- ing exposure to a high degree of heat without damage or attack by many chemicals. It can only be dissolved by nitrohydrochloric acid (aqua regia). Care has to be taken, however, that it is not exposed to the action of other molten metals such as lead, as the two metals will form an alloy if exposed to a sufficiently higbftemperature, and result in the ruin of the platinum, which is a very costly metal. In the form of foil, as held by a pair of tongs in the hands, it is very useful for testing the action of heat upon chemical substances placed on its surface, the foil being placed directly over the flame of a spirit-lamp or Bunsen burner. It can thus be ascertained whether the substance fuses or chars (indicating the presence of organic matter), or is volatile, or gives off a distinctive smoke or odour ; and if it burns, whether it does so with any notable feature or communicates any particular colour to the flame to which it may be exposed, and so forth. Platinum Crucibles are most useful for exposing sub- stances to heat with the view of burning off volatile or organic constituents, or of fusing refractory substances with 25 386 PLATINUM PNEUMATIC TROUGH PLATINUM (Continued) added chemicals (fluxes) in order to obtain them in a form soluble in some menstruum. Platinum Dishes are utilized for evaporation of solutions which are likely to attack glass or porcelain. Platinum Weights of small size are valuable because the metal does not tarnish in the air, and the weights are not easily corroded by accidental contact with chemicals as are copper and brass weights ; 0-5 gramme, 0-2 gramme, o-i gramme, and some smaller ones, are among those fre- quently employed. Platinum Wire is useful for stirring liquids which attack glass rods, and for exposing liquids or solids spread over its surface to the flame of a Bunsen burner, in order to note the distinctive features attendant thereon. For this applica- tion the wire is bent into a loop at one end, so that a bead of the liquid or solid to be tested may be held thereon, the other end of the wire being held by tongs, or fixed in a wooden handle, or fused into a glass tube. (See Borax, p. 65.) PLATINUM BASES (Organic) Combination of salts of the amines, such as the chlorides, with platinic chloride for example, methylamine platinichloride ((CH 3 NH 3 ) 2 PtCl g ). (See Amines, p. 28.) PLATINUM ORE Native platinum. PLUMBAGO Another name for graphite or black-lead. (See Carbon.) PNEUMATIC TROUGH An appliance used for the collection of gases, consisting of a trough made of glass or tinplate, and provided with a shelf as shown in figure. For use in con- nection with gases that are insoluble with water, it is charged with that fluid, so as to well cover the shelf near the top. In some other cases mercury is used, necessitating the employment of a stoneware, glass, or porcelain bath. The figure shows the trough in connection with a generator (Woulfe's bottle) PNEUMATIC TROUGHPOLARIZATION 387 PNEUMATIC TROUGH (Continued) such as is used for making carbon dioxide from marble and hydrochloric acid, the end of the bent tube being passed into the water in the trough and up underneath the test-tube (as shown) or other collecting vessel (filled with water and 'inverted and placed over the funnelled hole in the shelf), in which the gas is to be stored by displacement of the water. PODOPHYLLIN A kind of resin extracted from the roots of Podophyllum peltatum, soluble in alcohol and ether, and used in medicine. POISONS AND ANTIDOTES Acids Aconite Alkalies Antimony Arsenic Benzene Petroleum Paraffin Chlorine Chloral Chloroform / Carbolic acid } Copper \ Corrosive I sublimate ) Lead salts .. Magnesia, lime, or chalk made into a milk with water. Stomach-pump or emetic. Emetic, followed by dilute vinegar. Emetic, decoction of bark or strong tea, and keep warm. Emetic, followed by freshly precipitated ferrous oxide, or white-of-egg beaten up in milk, or magnesia. Emetic, fresh air and artificial respiration when necessary. Magnesia. (See Gassing.) Emetic, keep awake and artificial respira- tion when necessary. Olive oil, emetic or stomach-pump, fol- lowed by stimulants. Encourage vomiting, then give eggs beaten up in milk. Laudanum Morphia Opium Oxalic acid. Sodium sulphate or magnesia. Emetic or stomach-pump, or purified char- coal-powder if swallowed immediately after the poisoning, and keep patient well awake. Chalk and water freely. One of the best emetics is mustard half a tablespoonful mixed in half a tumbler of water, and for children one or two teaspoonfuls of ipecacuanha wine every ten minutes. Another good emetic for adults is a teaspoonful of sulphate of alumina. POLARIZATION Many liquids exhibit optical activity, and effect the rotation of a ray of polarized light when placed in a column between two Nicol prisms in a suitable instrument. 388 POLARIZATION POPULIN POLARIZATION (Continued) A Nicol prism composed of Iceland spar pure crystallized calcium carbonate is split along a diagonal plane and then cemented together again with Canada balsam. This gives a pencil of light, the vibrations of which are in one plane only, and light so obtained is said to be polarized. The polari- meter is the instrument which measures the angle through which the polarized ray is turned to the right or to the left. POLLUX (Pollucite) A complex silicate containing caesium, occurring in pegmatite, found in Maine, etc. POLONIUM A radio-active substance obtained from pitch- blende, to which no definite composition has yet been assigned. POLYBASITE A mineral compound sulphide of silver and antimony, found in some of the United States of America and elsewhere. POLYMERISM A form of isomerism. Substances having the same percentage composition but distinct in characters and differing in formulas as evidenced by determination of their molecular weights, as, for instance, aldehyde (C 2 H 4 O 2 ), which slowly changes into paraldehyde (C 6 H 12 O 3 ), the last named being the polymer and its molecular weight being a multiple of that of its originating compound. (See Isomerism.) POLYPEPTIDES Hydrolized derivatives of proteins re- sembling peptones in some respects, and of which the so-called amino-acid groups form conspicuous features. (See Albumins, Enzymes, and Proteins.) POPPY OIL is expressed from the seeds of the black poppy (Papaver somniferum, var. nigrum), which yield about 50 to 60 per cent. It contains about 8 per cent, of solid fatty acids, 30 per cent, oleic acid, 60 per cent linoleic acid, and 5 per cent, linolenic acid. It resembles olive oil in appear- ance ; its sp. gr. is 0-9249, saponification value 193 to 195, iodine value 153 to 157, and refractive index 1-457; it solidifies at 18 C., and is one of the drying class of oils. It is said to be used as food in some parts of Germany and France, and for mixing with light colours for use in painting, after being bleached in the sun. It is odourless and soluble in ether, chloroform, and carbon disulphide. POPULIN (or Benzoyl Salicin) (C 10 H 22 O 8 ) A soluble glucoside contained in the bark, leaves and root of the aspen (Populus tremula), and which can be artificially made from benzoyl chloride (C 7 H 5 C1O) and salicin (C 1? H 18 O 7 ). It yields salicin and benzoic acid upon hydrolysis. PORCELAIN PORPOISE OIL 389 PORCELAIN and earthenware articles are made of clay coated or glazed with some substance that fuses at a high tempera- ture, thus giving them a coating and at the same time binding the body of the material together in coherent mass. The best quality of China clay (aluminium silicate) is used for porcelain goods and the poorer qualities of clay for earthenware articles, the glaze for the former being felspar in finely powdered form suspended in water, into which mixture they are dipped before firing. " Cornish stone " consists of approximately equal parts of felspar, quartz, and clay, and is therefore a ready-made material. For earthenware goods, a " salt glaze " is used and applied by introducing salt into the furnace containing the ware, in which it is volatilized and decomposed by the heated sur- faces of the articles, causing the formation of a fusible silicate on their surfaces. Articles of stoneware, such as jars and drain-pipes, are salt glazed, while for many varieties of earthenware easily fused glazes containing lead or borax are used. The use of lead compounds is viewed with growing disfavour by reason of their poisonous effects in pottery works. For fine qualities of ware, such as Delft and Majolica, the surfaces are coated with an opaque white glaze containing stannic oxide (SnO 2 ). Some qualities of ware, such as flower-pots, etc., are not glazed, and this is true also of Spanish cooling vessels (alcarazzas) which are specially made porous in order to maintain a constant, slow evaporation and consequent cooling of the water contained in them. (See also Clays and Refractories.) POROSITY Possession of pores, interstices, or cavities looseness of binding. Animal charcoal, pumice stone, kieselgiihr, spongy platinum, and sponge are examples of porous articles. Many porous articles, particularly ordinary sponge, are absorbent and, in consequence, take up or hold in a mechanical sense, large quantities of liquids, which can in some cases be squeezed out by pressure, thus consolidating the porous material. The interstices between the atoms of compact solid and liquid bodies must be small, even if there are any inter- stices at all, so that porosity is often conspicuous by its absence glass, for example, being highly impermeable to oxygen, nitrogen, and water. (See Occlusion, p. 345.) PORPHYRY A form of felspar. PORPOISE OIL See Fish Oils. 390 PORTLAND CEMENT POTASSIUM COMPOUNDS PORTLAND CEMENT See Cement. PORTLAND STONE An oolitic limestone (calcium carbonate composed of minute grains. POTASH See Potassium Compounds. POTASH BULBS See Organic Analyses. POTASSIUM (Kalium, K) and its Compounds Atomic weight, 39 ' S P- g r -j 0*865 ; melting-point, 62-3 C. Potassium occurs abundantly in nature at Stassfurt, in Germany, in the form of saline deposits of various compositions viz., as chloride (KC1) in sylvinite (sylvine), as a double chloride of potassium and magnesium (KCl.MgCl 2 6H 2 O) in car- nallite, and as a compound sulphate and chloride (K 2 SO 4 . MgSO 4 .MgCl 2 6H 2 O) in kainite. There are similar and even richer deposits in Alsace (mostly pure sylvinite) estimated as sufficient for furnishing more than 300,000,000 tons of potassium oxide (K 2 O). In the Italian colony of Erythrea, considerable deposits have been found and worked during the recent war. Potassium is found in the soil as a product of decom- position of certain rocks (for instance, felspar) from which it finds its way into vegetable life, and so into the bodies of the animals that feed upon it. This accounts for the presence of potash in the suint or fat that is extracted from sheep's 'wool. Potash is now being recovered in this country from the flue gases and dust of iron blast-furnaces, and the industry is likely to attain considerable proportions. Blast-furnace gas contains from 4 to 6 grammes solid particles per cubic metre, which yield about 27 per cent, of potassium chloride. Common salt is introduced with the blast charge, and this, combining with the potassium contained in the iron ores, forms potassium chloride, which volatilizes and is recovered from the fume and dust. There is also a process for recovering it as sulphate from the gases and dust carried over in the stack gases of cement works, about 2 to 7 Ibs. being obtained per barrel of cement produced. In the form of nitrate (KNO 3 ) potassium is found in association with sodium nitrate in the nitrate deposits of Chili and Peru. The metal potassium is silver-white, lustrous and soft. It rapidly oxidizes in the air, its vapour taking fire, so that in the metallic state it has to be preserved in naphtha or kerosine. POTASSIUM COMPOUNDS 391 POTASSIUM (Continued) Potassium was formerly obtained by heating a mixture of potassium hydroxide (KHO) and carbon, the metal thus set free distilling over and being collected in naphtha, but it was a difficult process and has been superseded by another in which the fused potassium hydroxide is sub- jected to electrolysis, oxygen, hydrogen, and potassium being all set free. The potassium floats to the surface of the fused mass and is withdrawn from time to time under special precautions, whilst hydrogen gas is given off at the cathode and oxygen at the anode. In common with sodium, it decomposes water, hydrogen being liberated as follows : H 2 + K 2 =K 2 + H 2 . Potassium oxide (K 2 O) can be obtained as a grey crys- talline body of specific gravity 2*32, and when dissolved in wate- it forms a solution of potassium hydrate (hydroxide), or caistic potash, as it is also called : i.e, a combination of potassium oxide and water, Tvo other oxides are known viz., the dioxide (K 2 O 2 ) and :he tetroxide (K 2 O 4 ) but they are comparatively un- important substances. Pctassium Chlorate (KC1O 3 ) is a crystalline body, soluble in witer, which is manufactured on a considerable scale chiely by the electrolysis of potassium chloride in a state of slution, the potassium hydroxide and chlorine thus procuced being allowed to mix at a temperature of 70 C., thus producing the chlorate, which can be obtained from the iolution by evaporation and crystallization. Rtassium chlorate is largely used in the preparation or exposives, matches, and fireworks. It melts at above 36^ C., and at 380 C. begins to give off oxygen. (See Chorine, p. 112.) Jotassium Carbonate (K 2 CO 3 ) was originally obtained frcn the ashes of wood hence the name " pot ashes," ani is still extracted from this source in some parts of Canada and the United States of America, where timber is atundant. It is soluble in water and used in the manu- facture of soft soaps, glass-manufacture, and wool-washing. In the anhydrous form it is very deliquescent, and it fcrms a crystalline salt with water (K 2 CO 3 3H 2 O); there i< also a potassium hydrogen carbonate or so-called bi- arbonate (KHCO 3 ), used in making baking-powders. 392 POTASSIUM COMPOUNDS POTASSIUM (Continued) Potassium Cyanide (KCN) is, a white, deliquescent, soluble, crystalline salt of very poisonous character largely used as a solvent of gold in certain methods of extracting that metal from its natural sources* (See Cyanogen, p. 149, and Gold, p. 233.) Caustic Potash (KHO) is prepared by the action of slaked lime or milk of lime (CaH 2 O 2 ) upon potassium carbonate, when calcium carbonate is precipitated and potash passes into solution, as shown by the equation K 2 C0 3 + CaH 2 2 = CaC0 3 + 2KHO. / The solution is concentrated by evaporation first of all in iron vessels, and finally to dryness and fusion in silver vessels. It is, however, for the most part now manufactured by an electrolytic method from potassium chloride. It is a very deliquescent and caustic substance, and when dissolved in water, great heat is developed. It is made of various strengths, and extensively used in the manufacture of soft soaps. Potassium Nitrate or Nitre (KNO 3 ), also knowiias salt- petre, is largely used as a fertilizer, for picklir* meatj in the manufacture of gunpowder, and in pyrotech ' is a white, crystalline salt, readily soluble in wate ics. It , and is for i the most part obtained from Chili nitre by steaniheating a solution of it in admixture with one of potassiumchloride (KC1), when a double decomposition occurs, expr follows : NaNO 3 + KCl=KN0 3 Under the working conditions of the process, mo ssed as of the NaCl is precipitated in a crystallized form and removed, and the KNO 3 is obtained later by crystallization of the mother-liquor and purified by recrystallization. Potassium Chloride, Bromide, and Iodide (KC1, Kir, and KI) are all white, crystalline salts readily soluble inwater. The chloride is used as a fertilizer ; the bromide is ised in photography and medicine, and the iodide is a vauable medicinal agent. Potassium Fluoride (KF) forms a white, deliquscent hydrate with water (KF.2H 2 O), and finds some ue in etching glass. Potassium Sulphides include K 2 S, K 2 S 2 , K 2 S 3 , and I 2 S 5 , POTASSIUM COMPOUNDS 393 POTASSIUM (Continued)- all of which are soluble in water, and are decomposed by acids, evolving hydrogen sulphide (H 2 S). Potassium Sulphates The sulphate and bisulphate (K 2 SO 4 and KHSO 4 ), are both colourless and crystalline, and to some extent soluble in water, although not so soluble as most of the other potassium compounds. The ordinary sulphate, which melts at 1,072 C., is used in glass- manufacture, as a fertilizer, and in the preparation of alums, whilst the bisulphate is used as a flux. Potassium Sulphite (K 2 SO 3 ) and potassium hydrogen sulphite or acid potassium sulphite (KHSO 3 ) are crys- talline salts soluble in water, both of which (and particu- larly the latter) are used in the brewing industry and as sources of sulphur dioxide. Potassium Manganate and Permanganate See Man- ganese, p. 306. Potassium Acetate (K(C 2 H 3 O 2 )) A white, crystalline powder, soluble in water, used in medicine, etc. Potassium Phosphate (KH 2 PO 4 ) A colourless, crystal- line salt used in compounding baking powders and in medicine. Potassium-Sodium Tartrate (Rochelle Salt) (KNa(C 4 H 4 O 6 ), 4H 2 O) A colourless, crystalline salt which loses its water at 215 C. Used as a depilatory and in medicine. Potassium Sulphocyanate (KCNS) A colourless, crystal- line compound used in making freezing mixtures and making artificial mustard oil. Potassium Oxalate (K 2 C 2 O 4 H 2 O) is a colourless, crystal- line salt soluble in water ; so also is the potassium, hydro- gen oxalate (KHC 2 O 4 ,H 2 O) (sometimes called binoxalate) and the acid potassium oxalate (KHC 2 O 4 ,C 2 H 2 O 4 ,2H 2 O) (also known as quadroxalate). Potassium Bitartrate (KHC 4 H 4 O 6 ) is a white, crystal- line, soluble salt,- used in compounding baking-powders. (See Tartar.) Potassium Chromate and Bichromate . (See Chromium, P- "5-) Prussiate of Potash (Red) or Potassium Ferricyanide (K 3 Fe(CN 6 )) A crystalline, poisonous substance of blood- red colour, readily soluble in water, which forms with solutions of many of the heavy metals, precipitates of characteristic colours ; hence its use in dyeing and calico- printing when used alone, or with solutions of iron salts 394 POTASSIUM COMPOUNDS PRINTING INK POTASSIUM (Continued) for the production of blue colours on wool and cotton. It is also used in connection with the discharge of indigo- blue colouring from calico and the preparation of some pigments. It is made by the action of chlorine upon the yellow prussiate of potash. Prussiate of Potash (Yellow) or Potassium Ferrocyanide (K 4 Fe(CN 6 )) is a crystalline substance of lemon-yellow colour, readily soluble in water but is not poisonous. It is made by heating a mixture of nitrogenous material such as dried blood, horn and parings of hides, with an equal weight of potassium carbonate and one-third of their weight of iron filings. There is also a process of making it from the " spent oxide " from gasworks which contains cyanogen compounds. Like the red prussiate, it is manufactured on a large scale for use in dyeing and calico-printing, also in the preparation of Prussian blue and in processes of electro-plating and electro-gilding. POTATO SPIRIT See Fusel Oil. POTTERY See Porcelain. PRASEODYMIUM (Pr) Atomic weight, 140-9 ; sp. gr. 6-4754. A little known and extremely rare element of the cerium group occurring in the earth didymia and monazite sand. It has been isolated by the electrolysis of its anhydrous chloride. It decomposes water, melts at 940 C., and gives two oxides, one of greenish-white colour (Pr 2 O 3 ), and another which is nearly black (Pr 4 O 7 ). The salts, including a chloride (PrCl 3 ,7H 2 O) and a sulphate (Pr(SO 4 ) 3 ,8H 2 O), are green in colour. PRECIPITATE To deposit or fall in the solid state out of a solution. For example, when a solution of sodium chloride is added to one of silver nitrate, the following interaction takes place : NaCl + AgN0 3 = NaN0 3 * AgCl, and the silver chloride, being insoluble, is thrown out of solution as a white precipitate. PREMIER JUS The oily fat expressed from beef-fat at 48 C. through filter-cloths. PRIMULIN See Dyes. PRINTER'S IRON LIQUOR Ferrous acetate (FefC 2 H 3 O 2 ) 2 ) ; used as a mordant in dyeing. PRINTING INK See Inks. PRODUCER GAS PROTEINS 395 PRODUCER GAS is made by passing air over red-hot coke or coal, thus generating a mixture of carbon dioxide (CO 2 ) and carbon monoxide (CO) with the nitrogen contained in the air used. It contains about 30 per cent, of carbon monoxide and is largely used for many purposes on account of its cheapness. (See Gas, p. 216, and Nickel, p. 330.) "PROMETAL" A variety of cast iron specially applicable to the construction of furnace parts. PROOF-SPIRIT Alcohol containing 49-28 per cent, real alcohol by weight, and 57 -10 per cent, by volume, having a sp. gr. of 0-920 ; every additional 0-5 per cent, alcohol above that is described as " i degree over proof." The factor for calculating proof-spirit from volume percentage is 1-7535- PROPANE See Hydrocarbons. PROPIONIC ACID (C 3 H 6 O 2 ) One of the normal fatty acids of small importance as a natural product, said to be con- tained in the products of wood distillation, also in cocoa-nut milk when turned sour and in crude oil of amber. It is a colourless, oily acid, which boils at 140-7 C., has a sp. gr. 0*987, is soluble in water and alcohol, with an odour something like that of acetic acid. PROPYL ALCOHOL See Alcohols. PROPYLAMINE See Amines. " PROTARGOL " A protein compound of silver used as an antiseptic and in medicine. PROTEINS The name given by chemists to a great variety of colloidal nitrogenous bodies of animal and vegetable origin and albuminous character like egg albumin and blood albumin, globulins (such as fibrin and globulin from the lens of the eye), and gluteins (of vegetable origin, etc.); but which, while admitting of some rough classification according to their varying properties, are all collectively grouped as albuminoids. Many of these complicated com- pounds, when in solution, are coagulated by heat, and when subjected to hydrolysis they yield the so-called albumoses, polypeptides, peptones, ammonia, and ultimately amino-acids, including glycine, leucine, tyrosine, aspartic acid, etc. Dry yeast contains about 50 per cent, of proteins, and is used in the preparation of a food product resembling ex- tract of meat named " marmite." (See Albumins, Enzymes, and Foods.) 396 PROTOCATECHUIC ACIDPUCHERITE PROTOCATECHTJIC ACID (C 7 H 6 O 4 or C 6 H 3 (OH) 2 CO,OH) A crystalline substance soluble in water, made by heating catechol (C 6 H 4 (OH) 2 ) with ammonium carbonate. PROTOPLASM See Bioplasm. PBOTYLE (Primordial Substance) The hypothetical ultimate form of matter of which, conceivably, the various elements are constituted, and to which they may in that case be re- ducible. The current opinion is that the so-called elements are not absolutely elemental in character, and really con- sist of the same primordial substance, but differing in properties according to their structure and the varying conditions under which they are revealed. (See Atoms, Elements, and Matter.) PROUSTITE A mineral double sulphide of silver and arsenic (3Ag 2 S.As 2 S 3 ) found in Arizona, New Mexico, etc. PRUSSIAN BLUE (Ferric Ferrocyanide) (Fe 4 (Fe(CN) 6 ) 3 ) The name of a blue pigment (compound of iron and cyanogen) made from potassium ferrocyanide and ferric salts, used in dyeing and making inks and paints. There are various formulae for making the several varieties of Prussian blue (Chinese and bronze blues), but they may be stated to be based generally, upon the action of potassium chlorate and sulphuric acid on a mixture of potassium ferrocyanide and ferrous sulphate in hot solution. Turnbull's Blue (ferrous ferricyanide) is Fe 3 (Fe(CN) 6 ) 2 . PRUSSIAN GREEN is prepared by the long-continued action of chlorine upon potassium ferrocyanide. PRUSSIC ACID A common name for hydrocyanic acid (HCN). (See Hydrocyanic Acid.) PTOMAINES The name given to certain chemical compounds resulting from the action of micro-organic life in the process of putrefaction. They are of a nitrogenous basic nature possibly alkaloidal and very poisonous. Several of these substances have been isolated, including a complicated animated body named " putrescine " (tetramethylene di- amine) and another named " cadaverine " (pentamethylene diamine). PTYALIN The active principle of saliva which by its action on starchy food converts the starch into sugar, thus behav- ing as an enzyme. It is present in saliva to the extent of about ij parts per 1,000, and is most active at 40 C. (See Enzymes.) PUCHERITE (BiVO 4 ) A rare mineral vanadium compound of bismuth. PULEGONEPURPURIN 397 PULEGONE (C 10 H 16 O) A constituent of some essential oils (including pennyroyal oil) in the nature of a ketone, isomeric with ordinary camphor. It gives a hydrochloride, C 10 H 17 OC1. PUMICE-STONE A porous lava of volcanic production, prob- ably derived from felspar, which floats in water, and is com- posed largely of silicate of aluminium. In a finely powdered state it is used as an abrasive and as a base for carrying catalysts. The seat of the Italian pumice industry is the volcanic island of Lipari. PUMILINE The essential oil from the leaves of Pinus piimilio (coniferae), used for inhalations. PUMPS (EXHAUST) Contrivances for reducing the pressure within vessels and thereby creating more or less vacuity. One such apparatus is known as the filter or water pump, in which a jet of water under pressure escapes in such a way as to cause air to be drawn by suction from the space to be exhausted. The " Sprengel " pump is an appliance in which mercury is used instead of water, and by its means the pressure may be reduced to o'ooi mm. of mercury. The "Topler" mercury pump is even more effective, giving a vacuity of o'ooooi mm. of mercury, and when coupled with the use of charcoal to assist in the absorp- tion of any remaining gas in the vessels to be exhausted, an enormously enhanced result is attained. Even greater claims are made on behalf of the Gaede pistonless pump ; but the greatest degree of exhaustion is said to be realized by an arrangement in which liquid air and charcoal are used in association. PURPLE OP CASSIUS A purple - coloured body obtained in the form of an impalpable precipitate by adding a solution of tin chloride (SnCl 2 ) to a solution of gold, or by adding a neutral solution of gold chloride to one of the mixed stannous and stannic chlorides. A purple of fine tint is produced when the tin chloride is first of all added to a solution of ferric chloride until a shade of green is obtained and then adding this mixture very gradually to a solution of gold chloride (AuCl 3 ). The precipitate, when collected and dried, forms the so-called purple or powder of cassius, which is used as a colouring material in the red glass of Bohemia. PURPURIN (C 14 H 8 O 5 ) A red colouring matter, being a valuable dye extracted from madder by the same process 398 PURPURINPYRIDINE PURPURIN (Continued) as alizarin and separated therefrom by its greater solubility in alum liquor. From strong alcohol it crystallizes in red needles. It is more soluble in water than alizarin and is produced synthetically from anthracene. PUS Creamy matter resulting from inflammation of wounds, and found in abscesses, consisting of serum and degraded tissue, crowded with white corpuscles (leucocytes) which have undergone degenerative change, and generally accom- panied with abundant micrococci and bacteria. It is very subject to infection or putrefaction, thus leading to the production of some of the products associated with the hydrolysis of albuminoid matters. (See Ptomaines.) PUTREFACTION The expression by which is indicated a number of chemical changes in animal and vegetable com- pounds, which are in the nature of hydrolysis and oxidation initiated by microbes. (See Bacteria, Microbes, Ptomaines.) PUTTY A mixture of whiting (calcium carbonate) and 18 per cent, linseed oil, with or without added white-lead. PUTTY POWDER Impure stannic oxide, containing about 25 to 50 per cent, of that substance, with from 71 to 46 per cent, of lead oxide, and 4 per cent, of impurities ; used in enamelling and for polishing. (See Tin.) PYRARGYRITE A native compound of antimony and silver sulphides (Ag 3 SbS 3 ), mined in the United States of America and New Mexico. PYRENE (C 16 H 10 ) A crystalline hydrocarbon accompanying chrysene,etc., contained in the distillate from coal tar coming over above 360 C. It melts at 149 C. PYRETOL The active principle of Insect Powder very poisonous to cold-blooded animals. (See Insect Powder.) PYRIDINE (C 5 H 5 N or CH(CH.CH) 2 N) A practically colour- less, liquid, basic substance of penetrating, sharp odour, contained in tar and bone oil, and present also in tobacco smoke. It has a sp. gr. of 0-9746, boils at 115 C, and is soluble in water, alcohol, ether, benzol, etc. It can be extracted in association with some of its homologues from the lower-boiling fractions of tar distillates by agitation with sulphuric acid, in which they dissolve, and in a pure state by heating its carboxylic acid with lime. It is used to some extent as a remedy for asthma, also as a denaturant for alcohol, and is a valuable solvent used in the rubber, paint, and other industries. Chemically, it has a ring constitution similar to benzene. PYRITES PYROLU SITE 399 PYRITES The mineralogical name of a number of natural compounds consisting of sulphides (chiefly iron and copper). There is a large consumption of pyrites in this country in connection with the manufacture of sulphuric acid, imports coming from Spain, Portugal, Norway, and other parts, in addition to that which is mined in Ireland and Cornwall. Iron pyrites (FeS 2 ) exist in many countries and in several varieties. A large proportion of pyrites is so-called cuprous pyrites (Cu 2 S,Fe 2 S 3 ). Many others are of arsenical char- acter. One of the arsenical pyrites is named mispickel and has the composition FeAs 2 ,FeS 2 ; others contain a notable quantity of nickel. The silver and copper contained in pyrites used in the sulphuric acid manufacture are recovered from the burnt ore by chemical processes. The Rio Tinto iron pyrites contains about 50 per cent, sulphur, 40 per cent, iron, from 1-5 to 3-80 per cent, copper and i oz. 4 dwts. of silver per ton; the Tharsis pyrites about 3-5 per cent, copper and 15 dwts. silver; and the San Domingo (Mason's) about 370 per cent, copper and 15 dwts. of silver. In the re- covery of the copper, great care has to be taken to first of all get rid of the arsenical constituent. (See Copper and Iron.) PYROCATECHIN. See Catechol. PYROGALLIC ACID or PYROGALLOL (C 6 H 6 O 3 or C 6 H 3 (OH) 3 ) can be obtained from gall nuts, but is best obtained by heating gallic acid (C 7 H 6 O 5 ) with water in an autoclave, thus causing the elimination of carbon dioxide. It is a white crystalline substance which melts at 132 '5 C. and can be sublimed without decomposition ; is soluble in water, and is a very powerful reducing agent for silver salts, which gives it a use in photography as a developer. Dissolved in alkali, it has a great affinity for oxygen (see Nitrogen, p. 333, and Organic Analyses, p. 354), and so is much used in gas analysis. With a solution of a ferrous salt it produces a beautiful indigo colour. Commercial samples exhibit a melting-point of from 125 to 132 C. PYROLIGNEOUS ACID The crude acetic acid liquor obtained by the dry distillation of wood. The acid distillate is neutralized by lime and the calcium acetate thus obtained is distilled with hydrochloric acid, thus yielding the acetic acid as distillate. PYROLUSITE The most abundant manganese ore and one of the richest in its oxygen content, containing from 80 to 87 per cent, of red manganese oxide, and 10 to 14 per cent. of oxygen. It is imported chiefly from Spain and is largely 400 PYROLUSITE PYROXYLIN PYROLUSITE (Continued) used in the manufacture of chlorine, although not to the same extent as in the days before the Weldon process was introduced for the regeneration of manganese from the waste liquors. (See Chlorine and Weldon Chlorine Process.) PYROMETERS Instruments for determining high tempera- tures, such as those of furnaces and the fusing-points of metals. They are of various classes, including the " contact " or " immersion " type, being so called because one part of the pyrometer is immersed in the heated material ; and the " distance" type, in which no such part is immersed. The mercury thermometer is a simple form of the first-named class, and can be applied in respect of temperatures up to 500 C. The thermo-electric pyrometer consists of two dissimilar metals in wire form, at the tip of which is a rod enclosed in a protecting tube, and this receives the heat and is termed the " hot junction," while the other ends of the two wires are outside the source of heat ("cold junction"). The temperature registered on an indicator is the difference between that of the two junctions. Many combinations of metals are available. Nickel chromium alloys are stated to give the highest electro-motive force in commercial use, and are useful for temperatures up to about 1,360 C. PYROMORPHITE (Green Lead Ore) (3Pb 3 P 2 O 8 ,PbCl 2 ) A natural lead compound in the nature of a chlorophosphate found in some of the United States of America. "PYRONIUM" A proprietary opacifying substitute for tin oxide in enamels, 3 per cent, of which and 3 per cent, of tin oxide giving better results, it is claimed, than 8 per cent, of tin oxide alone, in leadless enamels and being much cheaper. PYROPHORIC ALLOYS (Ferrocerium) Alloys made of a mixture of rare-earth metals (chiefly cerium) with about 30 per cent, of iron ; a sparking substance used in making cigar lighters and for tracing the flight of shells, the friction of the air generating sufficient heat to cause a piece of the alloy attached thereto, to burst into flame and thereby indicate their path. The cerium is obtained from the residues of the gas-mantle industry. PYROXYLIN (Gun-cotton) is typical of a number of substances used in competition with oil products, in the preparation of artificial leather cloth and oil varnishes, and consists of a solution of nitrated cellulose in a solvent of comparatively PYROXYLIN QUICKLIME 401 PYROXYLIN (Continued) high boiling-point, mixed with castor oil or nitrated castor oil to impart body and flexibility to the product. (See Cellulose.) PYRRHOTIN (Pyrrhotite) Magnetic pyrites of varying com- position and crystalline character found in many districts. PYRROL (C 4 H 4 NH) A constituent of bone oil. It is a liquid basic body of the furane group soluble in alcohol and ether ; sp. gr. 0*9669 and boiling-point 130 C. QUALITATIVE ANALYSIS is the term applied to the methods used for ascertaining the nature of the constituents of substances. (See Reagents.) QUANTITATIVE ANALYSIS is the term applied to the methods used for determining the amount of each con- stituent of any substance. (See Organic Analyses and Volumetric Analyses.) QUARTZ An anhydrous crystalline form of silica. (See Silica.) QUASSIA WOOD (Bitter Wood) comes from a tree (Picrana excelsa) which grows in Jamaica and the West Indies. It contains about 0*03 per cent, of a very bitter crystal- line substance named quassiin (C 32 H 42 O 10 ), which is soluble in alcohol and to a smaller extent in water. Infusions of the wood are used in medicine and as a bitter. QUEBRACHO EXTRACT, used in tanning and dyeing as a substitute for catechu and sumach, is obtained from the wood of trees (Aspidosperma) which grow abundantly in Brazil and the River Plate districts of Argentine and Paraguay. The dry extract contains about 65 per cent, tannin. The production for 1919 amounted to upwards of 170,000 tons. QUERCITIN (C 15 H 10 O 7 .2H 2 O) A brown crystalline substance of melting-point 313 C., soluble in alkaline solutions and used in dyeing. It is prepared from quercitrin. (See Rutin.) QUERCITRIN A yellow crystalline dyestuff of glucoside character (C 21 H 20 O n ,2H 2 O) extracted by alcohol from the bark of the Quercus tinctoria, which yields quercitin (C 15 H 10 O 7 ) and rhamnose (C 6 H 12 O 5 ) upon hydrolysis. QUERCITRON The powdered bark of Quercus tinctoria, the extract of which contains quercitrin together with other substances ; used in tanning and in dyeing textiles. QUICKLIME See Calcium. 26 402 QUICK SI L VER RADIA TION QUICKSILVER See Mercury. QUILLAYA (Quillaja) /The bark of Quillaya saponaria, from Bolivia, Peru, and Chili, which yields a soapy kind of infusion containing saponin which is used for washing, as a foam producer in soft drinks, for shampooing, and as an emulsifier. (See Saponin.) QUINIC ACID (C 7 H 12 O 6 ) A white crystalline substance found in coffee beans, quinine bark, the common holly, and the leaves of some conifers and the cedar ; soluble in water and alcohol ; melting-point, 160 C. . QUINIDINE See Cinchona. QUININE See Cinchona. QUINOL See Hydroquinone. QUINOLINE A colourless, highly refractive liquid of peculiar characteristic odour, present in coal tar, and produced synthetically from aniline. It is a tertiary amine which is soluble in water and alcohol, boils at 239 C., has a sp. gr. 1*08, and is used in medicine and for preserving anatomical specimens. QUINONES A group of yellow compounds used in dyestuffs, obtained from benzene and its derivatives, by methods which replace 2 atoms of hydrogen by 2 of oxygen for example, quinone (C 6 H 4 O 2 ), which is prepared from a solution of quinol by the addition of chromic acid. RACEMIC ACID ((C 4 H 6 O 6 )2H 2 O) A transparent crystalline form of tartaric acid (C 4 H 6 O 6 ) obtained from tartar mother- liquor devoid of the power of turning the plane of polarized light, and therefore termed "inactive." It is soluble in water, melts at 205 C., and admits of division into two modifications : the one known as dextro-tartaric acid, which turns the polarized light plane to the right ; and the other as laevo-tartaric, which affects it to the left. (See Tartaric Acid.) RACEMIC COMPOUNDS are mixtures of equal parts of the dextro and laevo modifications (isomers) of compounds, and are, in . consequence, optically inactive racemic acid, for example. RADIANT MATTER See Radio-activity. RADIATION Throwing out or dispersion as, for example, the heat radiated from an open fire. (See Heat.) RA DIG A LSRA DIO-A CTI VITY 403 RADICALS (or RADICLES) Groups of atoms which behave in replacement value, as atoms in a number of com- binations for example, the group CH 2 in the homo- logous " paraffin " series of hydrocarbons ; the group HO in the alcohols ; the group C 3 H 5 (glyceryl) in fats ; the group NO 2 in nitric acid and many explosives; and the group SO 2 in sulphuric acid. These radicals may be mono, di, or trivalent, etc. that is to say, capable of replacing one, two, or three monovalent atoms. In the case of nitric acid (HNO 3 ), the constitutional formula is therefore expressed as water in which an atom of hydrogen is replaced by NO 2 viz., H,NO 2 ,O; that of ethyl alcohol (C 2 H 6 O) as C 2 H 5 HO ; and sodium ethoxide as C 2 H 5 NaO. RADIO-ACTIVITY is a phenomenon which appears to depend upon the expulsion of certain electrons from substances, thus explaining the apparent conversion of one kind of matter into another as referred to under the heading of Atoms ; and this is done without materially disturbing the general character and properties of the residual substance in its relation to the groupings (when dealing with elements) of the periodic law (see Lead). In other words, elements may exist generally identical in chemical and physical properties, but having different atomic weights. Crookes originally found that when an electric current was passed through a glass tube previously exhausted of air to a great extent, certain rays looking like light, pass from the cathode to the anode, although the anode is the pole at which the current enters. These rays, called " radiant matter," are able to drive a little vane placed in their path that is, to exercise some small mechanical pressure. These emanations are now regarded as electrons, and will pass, as afterwards ascertained, through thin sheets of metal. The cathode rays may be made to converge by the use of an aluminium cup, thus producing a green phosphorescent spot on the glass. They travel in straight lines, and cast a strong shadow from any intervening object placed in their path ; they also develop great heat, which may rise to the melting-point of platinum. The so-called X rays are a form of light lying beyond the visible end of the spectrum (see Rontgen Rays), and Becquerel, in his search for the possiMe emission of Rontgen rays by fluorescent substances, encountered rays which are considered to be corpuscular. For example, a double salt of uranium and potassium, without exposure to light, was found to emit rays which affected a photographic plate, and 404 RA DIO-A CTI VITYRA DI UM RADIO-ACTIVITY (Continued) this was the first ascertained instance of so-called radio- activity. This discovery was followed by that of Curie and his wife, to the effect that the activity of the uranium compounds is due to the presence in them of some other very active substance viz., radium, which proved to be a million times more active than uranium. Then it was found that radium itself emits three different types of radiation : one known as the alpha rays, which are unable to pass through a few sheets of paper ; another, the beta rays which can be cut off by a thick sheet of lead, and the gamma rays, of more intensely penetrating character. The alpha rays are regarded as atoms of helium, the beta rays as identical with Crookes's cathode rays, whilst the gamma rays are viewed as identical with or similar to the X rays. Uranium is a typical radio-active substance, and by the loss of an alpha ray is transformed to a modified element, which by the loss of a beta ray is again changed into a further modified elemental form, thus illustrating the atomic changes referred to under the respective headings of Atoms, Elements, and Radium. According to Rutherford, the a-rays obtained from the nuclei of helium atoms constitute a powerful and effective agent for disintegrating and simplifying the nuclei of atoms generally, and he supposes that helium is one of the bricks of which the heavier atoms are built up, and that hydrogen is one of the products of the disintegration of oxygen. Among the outstanding problems to be satisfactorily solved is the nature and structure of the nuclear parts of atoms, but it is sometimes alleged that they are built up of hydrogen nuclei and electrons. RADIUM (Ra) Atomic weight, 226. Radium is a very rare, bright, white metal, melting at 700 C., and one of the more recently discovered elements, the chief sources of which are cavnotite and pitch-blende (minerals found in Cornwall, Colorado, and elsewhere, 500 tons of Colorado carnotiU yielding about i gramme of radium). It has remarkable properties and is supposed to be an atomic decomposition product of the metal uranium, resembling barium in its chemical properties and yielding crystalline salts, which are luminous in the dark, radio-active and emit heat : they are thus able to maintain a temperature higher than that of their surroundings. The chloride (RaCl 2 ) is a soluble yellowish-white crystal- RADIUM RAPE-SEED OIL 405 RADIUM (Continued) line salt, which, mixed with calcium sulphide, is used in making a luminous paint ; whilst the bromide (RaBr 2 ) is a white crystalline salt similarly employed, and both are used in medicine (chiefly in the treatment of cancer). The radiations of radium are used as a curative agency in medical science and its rays are very destructive of animal tissues. In emitting these radiations it undergoes spontaneous decomposition, giving out heat continually, and yielding some seven successive radio-active disintegration products, including niton, radio-lead (see Lead), and helium. (See Atoms, Elements, and Radio-activity.) It has been calculated that radium disintegrates at such rate that the time required for one-half of any given quantity to break up into other elements is about 1,670 years. The penetrating radium rays are capable of bringing about many chemical changes, among which may be instanced their action on toluene, resulting, it is stated, in the production of benzaldehyde and benzoic acid. RAFFINOSE (Melitriose) (C 18 H 32 O 16 ,5H 2 O) A soluble carbo- hydrate, very like cane sugar, but tasteless, found in the sugar-beet and in molasses. It is dextro-rotatory and splits up into other sugar-like bodies upon inversion. RAMIE (Rhea Ramie, or Chinese Grass) The fibre of several varieties of the genus Boehmeria, or the Rhea of Assam, now grown in India and Italy, and said to be nearly three times stronger than Russian hemp. It contains a large quantity (22 to 35 per cent.) of gum ; is used in China for making mats and sails ; in Saxony in making tapestry, tablecloths, damasks, etc., and is the principal yarn from which gas mantle fabrics are knitted and woven. RANCIDITY of butter, fats and oils, results from chemical changes brought about by enzymes produced by micro- organisms and the action of air, light and moisture. RAPE-SEED OIL (Colza Oil) A dark, non-drying, fatty oil of unpleasant odour extracted by pressure from rape-seed, a plant of the cabbage tribe of the genus Brassica (Brassica campestris). The best rape-seed comes from Shanghai and Hankow in a number of varieties, and a considerable quantity is raised in India and Japan. It yields from 33 to 50 per cent, of oil, which is yellowish in colour ; has a sp. gr. of 0-9132 to 0-9168 ; a saponification value of 170 to 179; refractive index, 1*472; iodine value, 94 to 100, and 46 RAPE-SEED OIL REFLECTION RAPE-SEED OIL (Continued) solidifies below o C. It is used to some extent for illumin- ating purposes, but chiefly for oiling woollen stuffs and as a lubricant. REAGENTS Solutions of various chemicals used for testing purposes in qualitative analysis. They comprise strong hydrochloric, nitric, and sulphuric acids ; dilute solutions of the same acids (of strength i part to 4 parts water) ; and various salts containing about 5 per cent, of the respective substances that is to say, 5 grammes by weight per 100 c.c. dissolved in water. For use in the practice of volumetric analyses, solutions of known strength, or so-called " standard solutions," are employed, the quantities of the constituents bearing the same relation to each other as the numbers which express their chemical equivalents. When they are made of such strengths . that a litre (1,000 c.c.) contains equivalent weights in grammes for example, 36'5 grammes (NaCl) in 1,000 c.c. they are termed " normal standard solutions." REALGAR See Arsenic. RECTIFICATION Purification of a volatile liquid by distilla- tion ; for example, a second distillation (redistillation) of alcoholic liquids is an act of rectification. REDDLE (Ruddle) An earthy, ochreous ore of iron, from haematite deposits, used by farmers for making a paste to mark sheep. RED ANTIMONY See Antimony, p. 34. RED-LEAD (Minium) See Lead, p. 288. REDONDA PHOSPHATES Natural phosphates of iron and aluminium found in the Islands of Redonda and Alta Vela. REDUCING AGENTS Substances are said to act as reducing agents, when, for example, oxygen is removed in some degree from an oxide by combination with hydrogen or carbon. Red-lead is thus reduced to metallic lead by strongly heating it upon a piece of charcoal. Reduction can be effected by the addition of hydrogen to an organic compound by the action of sodium amalgam. The manu- facture of aniline is carried out by a reducing action. (See Aniline. ) REFLECTION A luminous ray projected upon a mirror is thrown back or reflected at an angle, and polished objects reflect a great part of the heat which falls upon them. REFRA CTIONREFRA CTORIES 407 REFRACTION The effect which is produced when a ray of light passes from one medium to another ; making a body partially immersed in water look as if it were broken. REFRACTOMETERS Instruments for measuring the velocity of propagation of light in a substance, this velocity being inversely proportional to the refractive index of substances. The refractive index is constant for every pure substance under standardized conditions of temperature and pressure. There are a number of refractometers for various purposes, one of the best for purely scientific work being the " Pulfrich." The so-called " butyro "-refractometer is largely used for oils and fats, while another all-round useful instrument is the " Abbe," which is also utilized in the determination of melting-points. REFRACTORIES are substances difficult to fuse, and implies materials employed in the construction of furnaces, ovens, kilns, retort settings, furnace hearths, stoves, crucibles, etc., on account of their resistance to heat, abrasion, strain, and the action of gases and the chemical compounds to which they are exposed in such use. Clays, fireclays, and silica in the forms of flint, quartz, sandstone, and ganister, are described as acid refractories, containing as they do silicic acid alone or in combination (as in the clays) with alumina ; while chromite (natural chromate of iron), graphite, and plumbago, are neutral in character, and bauxite, lime, magnesia, and zirconia are examples of so-called basic refractories. Fireclay, being acidic in character, is destroyed when heated with bases such as lime; and magnesia, being basic, is destroyed when heated with an acid refractory such as clay. Mica, talc, alumina, and carborundum are further instances of refractories. The mineral chromite is largely used in the manufacture of bricks for lining steel and copper smelting furnaces. They usually contain about 33 per cent, chromic oxide, with less than 6 per cent, of silica, the bricks being com- pounded by mixing the powdered ore with water and a binding material such as tar, into paste form, moulding, drying, and burning up to 1,460 C. in kilns. Refractory mortars and cements employed for joining, patching, or binding, and as washes over surfaces, are sometimes made of corresponding materials, but slightly more fusible than those to be treated, so that a vitrified bond is formed upon the application of strong heat. Zirkite cement consists wholly of zirconia, finely ground 408 REFRA CTORIES-REGELA TION REFRACTORIES (Continued) and made into a paste with water, while silica bricks are generally used in the construction of electric furnaces. The clays used in the making of porcelain and earthen- ware, lose their chemically associated water when heated to from 480 to 600 C., and the temperature used in making non-absorbent or vitreous porcelain varies from 1,250 to 1,550 C., while that employed for porous or non-vitreous ware ranges from 1,150 to 1,250 C. In his work on " Refractories," by A. B. Searle, it is stated that fire bricks heated in a darkened chamber (as in a kiln) exhibit the appearance s noted below, at various given temperatures : Just-visible red ... ... 500 to 650 C. Cherry ... ... 850 to 900 C. Bright ... ... 1,000 C. Orange ... ... ... 1,100 C. Yellow ... ... ... 1,200 C. White ... ... ... 1,500 C. and that they begin to lose their shape when the temperature reaches to from 1,600 to 1,800 C. A German method of preparing ordinary bricks, so as to have a refractory character, consists in coating them with a mixture of 75 per cent, carborundum and 25 per cent, sodium silicate, and after drying, slowly heating, and burning in the mixture. REFRIGERATE To make cool. There are processes for refrigerating perishable and other articles based upon the cooling which is produced by causing volatile liquids like strong ammonia and liquefied carbon dioxide to assume the vaporous state. This change of state involves the con- sumption or absorption, so to speak, of heat, and is used for cooling chambers in which foods, etc., are kept A kilogram of liquid ammonia evaporated at - 10 C. ab- sorbs 322-3 calories. With regard to the preservation of meat and fish, it has been shown that, by sufficiently rapid cooling to a temperature that corresponds to the eutectic of a saline solution, the separation of frozen water as a visible phase is avoided, so that upon thawing, the system returns to its original state. Processes of refrigera- tion are often used in chemical investigations and operations. (See Heat and Freezing Mixtures.) REGULATION The freezing of water anew, brought about by the reduction of pressure, the melting-point of ice (o C. REGELA TION RESINS 409 REGULATION (Continued} under a pressure of i atmosphere) being affected by the alteration of pressure to a slight extent. REGULUS Metal reduced from oxides or other compounds by fusion with reducing agents. REICHERT-WOLLNY FAT VALUES The values of the volatile fatty acids contained in fats, represented by the amount of alkali required to neutralize them, as obtained by a special process of separation and distillation. REINSCH'S TEST FOR ARSENIC Is based upon the fact that if a clean strip of copper foil be immersed in an acidified arsenical solution, metallic arsenic is deposited on the copper, forming copper arsenide (Cu 5 As 2 ). RENNET An infusion of the inner membrane of the fourth stomach of the calf, used for coagulating milk in the manufacture of cheese. This coagulation is due to the action of an enzyme contained in the rennet which is sup- posed to be of a different class from those other enzymes which act either by hydrolysis or oxidation. (See Enzymes.) RESINATES Compounds of abietic, pimaric, and sylvic acids (resin constituents) " RESINITE " is the name of a sort of resin made by the action of formaldehyde upon phenol. RESINS A class of uncrystallizable vegetable products which are insoluble in water as distinct from gums (properly so called). They soften, as a rule, upon heating and are more or less soluble in alcohol, ether, benzine, turpentine, and other solvents. Many of them are exudations from living trees and some of these are supposed to result from oxidation of the volatile or essential oils which are secreted by them. These exudations are sometimes artificially facilitated by incisions made in the trees as in the case of crude turpentine. Others are of fossil origin but have been probably pro- duced by similar natural processes, while many others are extracted from plants by the use of solvents such as alcohol, benzene, or volatile oils. They are mostly yellow or brown in colour ; some are hard and fracture easily ; others are soft ; and some become electric when rubbed. Descriptions of some of the following will be found under their several names or under the heading of Balsams : Amber, Ammoniacum, Anime, Asafcetida, Benzoin, Burgundy, Capsicum, Copaiba, Copal, Dammar, Dragon's Blood, Elemi, Frankincense, Galbanum, Gamboge, Guaiacum, Gambier, Jalap, Kino, 410 RESINS RESPIRA TION RESINS (Continued) Kowrie, Lac, Mastic, Opopanax, Podophyllum, Sandarach, Scammony, Shellac, Storax, Tolu, and Valerian. (See also Balsams, Gums, and Mucilage.) The resins are largely used in making lacs, varnishes, rubber substitutes, etc. Common Resin (Colophony-Rosin) The residuum left behind in the retorts when crude turpentine (as it exudes from the pine-trees which produce it, and known also as galipot, and gum thus) is distilled. It is graded according to colour, from B, the darkest, to W W, the lightest, and is very much used in various industries, particularly in soap- making, having the property of combining with alkalies, thus forming a kind of soap. The saponification value of American rosin is about 170 to 180, and the iodine value about 122. When rosin itself is subjected to destructive distillation by greater heat, it is cracked or split up into a number of products, including rosin spirit and rosin oil, which pass over with the vapours and are condensed, whilst a pitch is left behind in the retorts. (See Rosin Oil, Rosin Spirit, Abietic Acid, Pimaric Acid, and Wood.) Synthetic Resins Many attempts have been made to produce satisfactory paint resins by polymerizing indene and coumarone two constituents of that fraction of coal- tar naphtha distilling between 160 and 185 C. by means of heat or the action of mineral acids. The products are yellowish to red substances of resinous character, soluble in ether, turpentine, acetone, and carbon disulphide, and are used in compounding rubber goods, paints, and varnishes. The formula of coumarone resin (otherwise known as benzo-furane resin) is given asC 6 H 4 .CH.O.CH. (See also Ester Gums, p. 182.) RESORCINEor RESORCINOL (C 6 H 6 O 2 or C 6 H 4 (OH) 2 ) isawhite crystalline phenolic body of antiseptic character, which can be prepared from many resins, such as galbanum and asafcetida, by fusion with caustic potash. It melts at 1 10 C., is soluble in water, alcohol, and ether, exhibits a therapeutical action mildly resembling that of carbolic acid, and is the basis of a number of dyes. Nitrous acid, for instance, transforms it into the so-called azo-dyes. RESPIRATION is, in essence, a chemical process whereby the blood is purified by absorption of oxygen from the air breathed into the lungs, carbon dioxide and aqueous vapour RESPIRATION RETORT OR STILL 411 RESPIRATION (Continued) being exhaled. The exhaled breath contains about 4*4 per cent, of carbon dioxide and 10*4 per cent, oxygen as com- pared with o'4 per cent, carbon dioxide and 20^96 per cent, oxygen present in ordinary air. The exhaled air contains, in addition to its moisture, traces of ammonia and organic matters that make overcrowded rooms unpleasant and unhealthy hence the importance of ventilation.- It is by combination of the oxygen, breathed into the body, with the haemoglobin of the blood-corpuscles that it is carried to all parts of the tissues, the latter in their turn giving up carbon dioxide, water, urea, and other excremen- titious products. (See Haematine.) The water given off in the exhaled breath in twenty-four hours has been estimated at 311 grms., or nearly n oz., and the carbon (in the form of carbon dioxide) at from 7-144 to 117 oz. (See also Air.) RETENE (C 18 H 18 ) A hydrocarbon accompanying pyrene, etc., in coal-tar distillate which boils above 360 C. (See Pyrene.) RETORT or STILL The illustration given below shows an apparatus employed for distilling purposes, consisting of the glass retort A (in which the liquid to be distilled is introduced through the tubulure, which can be closed with a glass This figure shows a thermometer passing- throug-h the cork fitting- the tubulure of the retort. stopper or cork) from which the vaporized substance passes to the condenser. The retort is held in position by a retort- stand, the body resting upon a sheet of wire gauze placed on one ring of the stand, while the neck of the retort can be secured or held in position by a smaller ring of the same stand. The heat is applied by a lamp placed below the retort. Liebig's condenser (B) is a simple appliance for assist- ing, by cooling, the condensation of vapours carried over from retorts, It consists of a water-jacket surrounding 412 RETORT OR STILL RHUS RETORT or STILL (Continued) a tube (connected with the retort), through which a stream of cold water is made to pass, entering by the attached tube, C, at the lower end, the warmer water thus replaced passing out of the condenser through the upper attached tube, D. The vapour passing away from the retort through the neck and tube is thus cooled and condensed to the liquid state, and flows out at E into any receiver, F, that may be placed there. Gas retorts for roasting coal in the process of coal gas making, are constructed on the same principle as laboratory retorts. REVERBERATORY FURNACE A furnace so constructed that the fuel flame in passing to the chimney-shaft is made to pass (reverberate) over the materials lying upon its bed these materials being the substances to undergo chemical change by action of the heat thus imposed. RHAMNOSE (Iso-dulcite) (C 6 H 12 O 5 ,H 2 O) A colourless crystalline carbohydrate or sugar-like body which melts at 93 C., obtained from several glucosides by hydrolysis. Quercitrin extract (from Rhamnus tinctoria) yields rhamnose. RHATANY ROOT (Krameria) The dried root of Krameria triandra (from Peru, Bolivia, and Brazil), containing from 8 to 20 per cent, of a tanning material. RHODAMINES A series of dyes nearly related to fluorescein, being colourless basic bodies of which the salts, such as the sulphate, are red. RHODIUM (Rh) Atomic weight, 103 ; sp.gr., 12-1. A metallic element found in platinum ores and belonging to the same group. It is white, lustrous, has a high melting-point (above that of platinum about 1,970 to 2,000 C.), and is used in the construction of electrical pyrometers. Three oxides are known viz., RhO, Rh 2 O 3 , and RhO 2 , and its salts include two chlorides (RhQ 2 and Rh 2 Cl 6 ), two sulphides (RhS and Rh 2 S 3 ), also a sulphate corresponding to the sesquioxide (Rh 2 (SO 4 ) 3 ). RHUBARB (Rheum), the dried rhizome of Rheum officinale, of which many species grow wild on the high lands of Central Asia, and many are cultivated; used for its purgative properties. The juice of the stems contains oxalic, malic, and citric acids. The root of rhubarb contains chrysophanic acid and other substances. English garden varieties (Rheum undu- latum and Rh. hybridum) are used as food. RHUS (Sumach) There are many species rich in tannicacid. RICERONTGEN RAYS 413 BICE A well-known grain (Ovyza sativa) (of which the chief con- stituent is starch) largely grown in Asia, South America, and the U.S.A. The sp. gr. of rice is about 1-43 to 1-46, and it contains from 73 to 78 per cent, starch, associated with fat varying from 0-5 to 7 per cent., albuminoids from 7 to 8-5 per cent., water about 13 per cent., and small proportions of mineral and other substances. Polishing decreases the nutritive elements in rice. The polishings contain oil and are usually sold as a fertilizer or feeding- stuff. (See Starch and Vitamines.) BICINOLEIC ACID (C 18 H 34 O 3 , or C 17 H 32 (OH)COOH) The glyceride of this fatty acid makes up some 80 per cent, of castor oil, and occurs also in curcas oil. It is yellowish, thick, solidifies at 15 C., has a sp. gr. of 0-945 '> * s soluble in alcohol, ether, etc., and is used in soap-making, the manufacture of Turkey-red oils, and dressing of textiles. BOBUEITE See Explosives. EOCHELLE SALT (KNaC 4 H 4 O 6 ,4H 2 O) A double tartrate of potassium and sodium, being a colourless crystalline com- pound, soluble in water, used in the preparation of certain baking-powders. EOCK CEYSTAL-See Silicon. EOCK SALT See Sodium. EOMAN CEMENT A form of hydraulic cement. (See Cement.) RONTGEN BAYS (X Eays) are certain rays given off from the cathode, comparable with light of extremely small wave- length, and are produced by passing an electric current through a highly vacuous glass tube and deflecting the rays by a mirror. They have the power of penetrating solid substances, such as animal tissues, paper, wood, and some metals, and acting on a photographic plate behind the object to be radiographed. It is thus possible to obtain shadowgraphs of portions of the human skeleton, as the bones are not so easily penetrated as are the skin, muscle, etc. The discovery of these rays has proved of great value in the examination of crystal structure ; also in practical surgery for locating bullets, etc., in the human body and for indicating the nature of fractures and dis- tinguishing between strains and dislocations. X Eays are now applied industrially for the detection of blow-holes and cracks in metals and brazings, the examina- tion of ferro-concrete, and the internal parts of clocks and watches, motor tyres, electric cables, cricket and golf balls, etc. (See Atoms, Electrons, and Radio-activity.) 414 ROSANILINES ROSIN OIL ROSANILINES The aminated 'bases of fuchsine or magenta dyes. The rosanilines are colourless, crystalline compounds, and only form dyes when united with an acid. Rosaniline (C 20 H 21 N 3 O) and para-rosaniline (C 19 H 19 N 3 O)are obtained by precipitation of their salts with alkalies. The actual dyes are the salts of these compounds, and include magenta, otherwise known as fuchsine (C 20 H 20 N 3 C1), rosaline nitrate (C 20 H 20 N 3 (NO 3 )), rosaniline acetate (C 20 H 20 N 3 (C 2 H 3 O)), and para-fuchsine (C 19 H 1? N 3 C1). These all dye wool and silk without a mordant, giving a magnificent fuchsine-red colour in solution, but are them- selves in crystalline form, of a bright metallic green lustre. They are soluble in hot water and alcohol. Rosaniline yields rosolic acid by treatment with nitrous acid. The formulae of rosaniline and para-rosaniline may be shown as below : Rosaniline. Para-rosaniline. X C 6 H 4 NH 2 . x C fi H 4 NH 2 . C.OH^-C 6 H 4 NH 2 . C.OH<^ ~C 6 H 4 NH 2 . X C 6 H 3 .CH 3 .NH 2 . X C 6 H 4 NH 2 . ROSE OIL. See Attar of Roses. ROSEINE See Fuchsine. ROSEMARY (OIL OF) The essential oil of Rosmavinus officinak, containing a terpene and other substances, and used in per- fumery. Sp. gr. 0-9 to 0*92, and rotation 4-0 to +15. ROSIN See Resins. ROSIN OIL The fraction from the destructive distillation of rosin which comes over after the rosin spirit, and up to about 400 C., constituting the bulk of the total distillate It exhibits a blue fluorescence and is a complicated mixture of hydrocarbons, phenols, and free rosin acids, ranging from 9 to 30 per cent. The last-named sub- stances can be removed, together with some of the dark colour, by treatment with caustic soda. In general, it resembles mineral oil, and is of sp. gr. varying from 0-92 up to over 1-12. There are a number of grades, some being practically colourless, and known as "pine oil," while another is dark blue, and known as " blue rosin oil," or " blue billy." It is soluble in ether, turpentine, carbon disulphide, etc., and finds use as a lubricant and as an adulterant of boiled linseed and other oils. ROSIN SPIRIT RUBBER 4*5 EOSIN SPIRIT (Pinoline) is a complex mixture of hydrocarbons and rosin acids, forming the distillate from the destructive distillation of rosin that comes over below 150 C., and amounting to from 2^ to 5 per cent, of the total distillate. It can be freed from associated acids by caustic soda, or refined by agitation with strong sulphuric acid and subse- quent redistillation. When rectified, it has a sp. gr. of about 0-856 to 0-883, is miscible with petroleum spirit and turpentine, and is used as a substitute for turpentine in the paint and other trades. ROSOLIC ACID (C 20 H 1(? O 3 ) A beautiful green-coloured crys- talline substance with a metallic lustre and melting-point 270 C., chemically related to aurine. It is soluble in alcohol and ether, and is used in dyestuffs. ROTATORY POWER See Polarization. ROTTEN STONE A mineral powder disintegrated rock of limestone nature found near Bakewell in Derbyshire and elsewhere, containing a large proportion of alumina ; highly prized for polishing purposes. ROUGE A common name for an amorphous form of ferric oxide, employed -for polishing glass, etc.; prepared by dis- tilling ferrous sulphate. RUBBER or CAOUTCHOUC This well-known substance is the concreted juice (latex) of certain tropical trees, including the Siphonia elastica, S. cahucha, Jatropha elastica, Ficus elastica, Valea gwnmifeva, Hevea caoutchouc, Hancoria speciosa, and Urceola elastica the fourth and last named being natives of India and sufficiently explaining the name India-rubber. Rubber is imported from various parts of South America, Asia, and Africa, the Para rubber being the best in quality, although 70 to 80 per cent, of the world's supply of rubber is now produced within the British Empire. The Ocotillo, or candleweed, of Arizona, is also stated to yield a kind of rubber to the extent of 200 Ibs. of gum to the ton. The rubber-juice, or latex, has a tendency to coagulate in the collecting cups, and to prevent this a dilute solution of formaldehyde, ammonia, sodium carbonate, or sodium sulphite preferably the latter is now used. The sub- sequent coagulation can be effected by chemical, physical, and biological methods, but acetic acid in the proportion of i part to 1,000 parts latex, is generally employed as the best coagulant. 416 RUBBER RUBBER (Continued) The total production of rubber in 1920 has been esti- mated at 360,000 tons. In the pure state, caoutchouc is white, but, as known in commerce, it is brownish -black in colour, supple, elastic, tenacious, very combustible, a bad conductor of heat, and a non-conductor of electricity. Below o C. it becomes rigid and brittle ; it softens when heated, and begins to melt at 120 C. Chemically, caoutchouc is a hydrocarbon allied to gutta- percha and turpentine, and can be made synthetically from isoprene (C 5 H 8 ) a volatile hydrocarbon liquid derived from turpentine. In sheet, tape, or thread form, rubber may be stretched very considerably without permanent loss of elongation. It is soluble in turpentine, naphtha, and benzene, and is extensively used in the manufacture of motor tyres, railway buffers, overshoes, macintosh garments, the cores of golf balls, and many other articles. When rubber is immersed in a bath of melted sulphur at 125 C. it takes up as much as from 15 to 20 per cent., but only 2 or 3 per cent, is really in chemical combination in the vulcanized rubber, as the bulk can be dissolved out. At a higher temperature, vulcanite or ebonite is produced and this product, unlike ordinary rubber, is not soluble in tur- pentine and benzene. This process of vulcanization is known as the " hot cure," but there is another one called the " cold cure," which consists in treating the rubber with a weak solu- tion of chloride of sulphur at ordinary temperatures, although this only results in a superficial vulcanization, and is not very widely used. The new gaseous treatment to be next described is of great promise : as the two gases are absorbed alternately by the rubber and by chemical reaction between them, sulphur is deposited throughout the material in a very finely divided or atomic form, thereby securing thorough vulcanization. It consists in exposing the rubber to the action of sulphur dioxide and hydrogen sulphide gases alternately, and is said to yield a product quite comparable to that produced by the older sulphur process, without the aid of heat. It can also be carried out in solution, and is the only process whereby rubber can be vulcan- ized in solution, affording, at the same time, the opportunity of incorporating with the rubber such substances as saw- dust and leather, owing to the non-necessity of using high RUBBER 417 RUBBER (Continued) temperatures, and thus producing many mixtures suitable for wall and floor coverings and other applications. The perishing of rubber goods proceeds much more quickly in the vulcanized articles than in those of pure rubber. It is said that plantation rubber that is, rubber as it comes from the growers may be stored for years without sensible loss of quality, and when vulcanized gives results comparable with freshly harvested material. Exposed to the light, rubber changes gradually in two ways, in which the oxygen of the air and light take active parts namely, first in the form of tackiness, and secondly into a brittle substance ; while in darkness there is no change. On the other hand, the vulcanized article begins to depreciate from the moment it is made. The life of vulcanized rubber is prolonged by storing in air saturated with moisture or petroleum vapour, being thus protected from oxidation and decomposition. A recent investigation concerning the permeability of rubber by gases has shown that it is one of dynamic equilibrium, in which the gas is dissolved at one side of the rubber, at a rate proportional to its solubility and partial pressure, and diffuses through the rubber, from which it evaporates on the other side. Its relative permeability to certain gases is shown by the following summary : Hydrogen = i *oo. Nitrogen ... ... ... ... 0-16 Air ... ... ... ... 0-22 Argon ... ... ... ... 0-26 Oxygen ... ... ... ... 0-45 Helium ... ... .... ... 0^65 Carbon dioxide ... ... ... 2*90 Ammonia ... ... ... ... 8 - oo Methyl chloride ... ... ... 18-50 Ethyl chloride ... ... ... 200-00 It is reported that the artificial production of so-called " methyl rubber " in Germany reached to the extent of 165 tons per month during the recent war. It is made by polymerization of the hydrocarbon dimethylbutadiene (primarily prepared from acetone) by placing it in her- metically sealed barrels and allowing it to remain undis- turbed for about six months at a temperature of 32 C., the rubber being thus obtained as a spongy white mass which has to be bored out of the containers. It lacks 27 418 RUBBER RUST RUBBER (Continued) elasticity when used for making soft rubber goods, and 11 elasticators," or oily materials, have to be incorporated for such applications. It is more useful in making so-called " vulcanites." (See Vulcanite.) RUBBER-SEED OIL, as extracted from the seeds of the Para rubber-tree, may possibly prove a substitute for linseed oil, but it has been shown that the seed depreciates on storage, and yields an oil containing up to 25 per cent, of free fatty acids, which is not generally suitable for that purpose. It exhibits a slower drying character as compared with linseed oil, and it is necessary to prepare a " boiled " oil for commercial purposes which is free from fatty acids. RUBIAN A name sometimes given to the principle contained in madder (the root of Rubia tinctoria), of glucoside character, which yields alizarin and glucose by hydrolysis. (See Alizarin.) RUBIDIUM (Rb) Atomic weight, 85-45; sp. gr., 1-52. A somewhat rare element met in association with potassium and sodium in the minerals lepidolite y porphyrites, and carnal- lite. It is a soft, silvery-white metal, melting at 38-5 C., and when sublimed, forms small needle-shaped crystals. It can be prepared by the electrolysis of the fused chloride, or heating the carbonate with carbon. It is capable of decomposing water and takes fire in the air, yielding the oxide, so that it has to be kept, like sodium, under naphtha. It gives off a green vapour when heated, and its salts, which are soluble, resemble those of potassium in their general characters. RUBY A gem of clear red corundum (aluminium oxide). (See Aluminium.) RUE (OIL OF) is obtained by distillation of garden rue (Ruta graveolens) with water, and contains a hydrocarbon with other bodies in admixture. It is viscid, of strong, un- pleasant odour and bitter taste, and is used medicinally as an anti-spasmodic, etc. Sp. gr., 0-83 to 0-84 ; and rotation, + to +2-30. RUM An alcoholic drink of characteristic odour, distilled from fermented molasses in the West Indies, and ordinarily containing about 48 per cent, alcohol. RUST The coating which forms on iron articles exposed to air and moisture, consisting of oxides and ferrous carbonate. RUSTLESS STEEL SACCHARIC ACID 419 RUSTLESS (STAINLESS) STEEL A chromium-iron alloy, containing from 12 to 15 per cent, chromium, and (for most purposes) not more than 0*45 per cent, of carbon, now largely used for the manufacture of cutlery, turbine blades, acid pumps, and exhaust valves for aircraft engines. It is not dissolved by strong or weak nitric acid, nor attacked by ammonia, but sulphuric and hydrochloric acids attack it readily. RUTHENIUM (Ru) Atomic weight, 1017; sp. gr., 12-26. A hard, brittle metal of the platinum group, with the ores of which it is found in association, also as laurite. It is practically insoluble in acids other than aqua regia, has a higher melting-point than platinum about 1,950 C.; forms a chloride (RuCl 4 ) which is deliquescent and very soluble in water, and other salts corresponding to the sesquioxide, which is one of the four oxides known namely, RuO, Ru 2 O 3 , RuO 2 , and RuO 4 . It is also said to form a potassium combination (KRuO 4 ) analogous to potassic permanganate (KMnO 4 ). RUTILE A rare crystalline mineral containing titanium in the form of oxide (TiO 2 ) occurring at Risor in Norway, at Graves Mountain in Georgia, etc. RUTIN (C 27 H 30 O 16 ,3H 2 O)t A substance originally discovered in rue (Ruta graveolens) and occurring in a number of plants, including Viola tricolor. It is a glucoside of pale yellow, crystalline character, sparingly soluble in water and alcohol, which upon hydrolysis yields glucose, rhamnose, and quer- citin. The petals of Eschscholtzia calif omica are said to contain 5 per cent, of rutin. RYE A cereal. (See Ergot of Rye.) SABADILLA Seeds of Asagraa officinalis, growing in Mexico, Guatemala, etc., from which veratrine is prepared. (See Veratrine.) SACCHARATE, STRONTIUM A sparingly soluble body prepared from the mother - liquor of molasses oy combination of the remaining crystallizable sugar therein with strontium oxide ; it can be decomposed by suspension in water and treatment with carbon dioxide. (See Sugar.) SACCHARIC ACID (C 6 H 10 O 8 ) A product of the oxidation of cane sugar, glucose, starch, etc., by nitric acid. It is deliquescent and readily soluble in water, 420 SA CCHA RI METER SA FFRON SACCHARIMETER An instrument for ascertaining the amount of sugar in a solution by determining the specific rotatory power that is, measuring the angle through which the plane of polarized light is turned when passing through its solution, in comparison with that of a solution of known strength. (See Polarization.) SACCHARIN (Benzoylsulphonic imide) (C 7 H 5 NSO 3 ) A syn- thetically prepared ammonia derivative or imide compound of one of the sulpho-benzoic acids ; white, crystalline, and having, in common with its hydrated sodium salt, a sweeten- ing power from 300 to 500 times that of cane sugar. It is prepared from toluene and is used as a sweetening sub- stitute for sugar, particularly in diabetic cases. SACCHAROMETER Hydrometer graduated to test the strength of sugar solutions by ascertaining their density, and reference to tables prepared from known strengths. SACCHAROSES are carbohydrates comprising the sugars and a number of substances closely related to them, together with the starches (amyloses) and cellulose. Cane and milk sugars are typical instances of one series ; glucose, fructose, and dextrose are members of a nearly allied class ; while the starches, dextrine and cellulose, are comprised in another series. Some of these individual substances are described under their several names, whilst a modern classification is referred to elsewhere. (See Carbohydrates.) SAFETY LAMPS, as used by coal-miners to obviate ex- plosions due to the accumulation of inflammable gases, are constructed on the known fact, that a flame has difficulty in crossing or passing through wire gauze. This is due to the conductivity of the metallic gauze, which carries away the heat of the burning flame inside the lamp to such an extent that the explosive gas outside the lamp is kept below the temperature necessary for its ignition. (See Coal.) SAFFLOWER (Carthamus), derived from the florets of Car- thamus tinctorius of the Levant and Orient, is a natural red colour used as a dyestuff for cotton goods without a mor- dant, and for colouring purposes. SAFFRON (Crocus) A yellow colouring matter, being the stigmas of the saffron crocus (Crocus sativus] indigenous in Spain, France, Greece and Asia Minor; used in cookery, as a dye, and in medicine. Spanish saffron is said to be the best. SAFRANINES SALICYLIC ACID 421 SAFRANINES A group of crystalline aniline dyes of metallic green lustre, including mauve, related to toluylene red. They are soluble in water, and dye red and violet. SAFROL (C 10 H 10 O 2 ) The essential constituent of sassafras oil (amounting to some 78 per cent.), and contained also in camphor wood and many other plants. It is a clear, colourless oil, of sp. gr. 1*1, soluble in alcohol and ether, and used in perfumery, the manufacture of heliotropin, piperonal, etc. It has the odour of sassafras, and upon cooling to 20 C. it crystallizes in rhombic prisms. Safrol, by oxidation with chromic acid, yields heliotropin. SAGE (OIL OF) An essential oil distilled from the fresh leaves of Salvia officinalis L. growing in north Mediterranean countries, containing the terpene named pinene (C 10 H 16 ). Sp. gr., 0*915 to 0-925 ; and rotation, + 10 to +25. SAGO Consists nearly entirely of starch, and is prepared in the islands of the Indian Archipelago from the pith of the stems of certain palms, including the Sagus vumphii W., 5. raffia Jacq., etc. SAL-AMMONIAC An old name for ammonium -chloride. SAL- VOLATILE Commercial ammonium carbonate. (See Nitrogen Compounds, p. 336.) SALICIN (C 13 H 18 O 7 ) A glucoside found ready formed in varieties of salix and populux (willows and poplars), also in the flower-buds of meadowsweet and in the green part of certain herbaceous spireas. In the pure state, it is a crys- talline odourless substance, soluble in water, and possesses febrifugal properties. In the human body it undergoes decomposition, giving rise to the production of salicylic acid. It is used as a specific in the treatment of acute rheumatism. (See Saligenin.) SALICYLIC ACID (C 7 H 6 O 3 or C 6 H 4 (OH)COOH) occurs natur- ally in the blossom of Spivcea ulmaria and in combination in oil of winter-green. It is a white, crystalline body, of melting-point 159 C., and can be easily obtained by chemical methods from salicin, coumarin, phenol, and indigotin. It is little soluble in cold water, but readily soluble in alcohol, ether, and hot water ; is a good antiseptic, and is much used medicinally. When heated with powdered glass or quicklime it breaks up into phenol and carbon dioxide. 422 SALIGENINSAND SALIGENIN (C 7 H 8 O 2 ) (o. Hydroxy-benzyl alcohol) The product of hydrolysis, accompanying dextrose, as produced from the glucoside named salicin (C 13 H 18 O 7 ). SALIVA An alkaline mixture of fluids secreted by various salivary glands (the ducts of which discharge into the mouth) containing an active principle termed ptyalin, which behaves as an enzyme and converts starchy matters into sugar. SALOL or PHENYL SALICYLATE (C 13 H 10 O 3 ) A white, crys- talline substance, possessing antiseptic properties and used medicinally for internal applications. It melts at 42 C., and is soluble in alcohol, ether, etc. SALSOLA A genus of seashore plants, rich in salts, which when burned, yield an ash containing sodium carbonate. (See Barilla and Kelp.) SALT See Sodium Compounds. SALT CAEE The crude sodium sulphate (Na 2 SO 4 ) as manu- factured by the old Leblanc soda-process. (See Alkali Trade and Sodium Compounds.) SALT OF LEMON See Salt of Sorrel. SALT OF SORREL (Salt of Lemon) An acid potassium oxalate ; a mixture of KHC 2 O 4 and KHC 2 O 4 + H 2 C 2 O 4 -f 2H 2 O. SALTPETRE (Nitre) See Potassium Compounds, p. 392. SALTS (CHEMICAL) See Chemical Compounds. SALVARSAN (" 606 ") (Kharsivan) is essentially a very com- plex organic compound (di-hydroxy-diamino-arseno-benzene dihydrochloride (C 12 H 12 O 2 N 2 As 2 ,2HCl,2H 2 O)) containing arsenic in combination, and is used in the treatment of syphilitic cases ; it is not, however, a chemically pure substance. SAMARIUM (Sa) Atomic weight, i5O'4. An extremely rare chemical element of the cerium group (obtained from didymia from ceria), trivalent in character, forming salts such as the chloride SaCl 3 6(H 2 O), the bromide SaBr 3 , and the iodide SaI 3 . There are two oxides (Sa 2 O 3 and Sa 4 O 9 ) ; the lower oxide and its salts are yellow. (See Praseo- dymium.) SAMARSKITE A complex yttrium mineral found in North Carolina and near Miask in the Ilmen Mountains, contain- ing cerium, columbium, tantalum, uranium, yttrium, etc. SAND Granular, hard, siliceous material in pulverulent form, Some kinds consist nearly entirely of silica. (See Silica.) SANDAL WOODSAPONIFICATION VALUE 423 SANDAL WOOD (Santal Wood) The dye wood of the Pterocarpus santalimis, a tree indigenous in the tropical parts of Asia. It is used in India for dyeing silk and cotton, to which it imparts reds of various hues. The active red colouring matter is named santalin (C2 3 H 18 O 6 (OCH 3 ) 2 ), and can be obtained in fine small red crystals insoluble in water, but soluble in alcohol. Sandal-wood oil, distilled by steam under pressure, from the wood of the East Indian Santahim album, contains from 90 to 96 per cent, santalol (an alcohol of the formula C-^H^O), and a terpene named santene, and is used in perfumery and medicinally in the treatment of gonorrhoea. The East Indian oils have a sp. gr. of from 0*973 to 0-982 ; optical rotation, - 14 to -21; and refrac- tive index, 1*5023 to 1*5093. The West Indian oil has a sp. gr. of 0-960 to 0-976; optical rotation, +18 to +29; and refractive index, 1-5078 to 1-5096. The Western Australian oil, from Fusanus spicatus R.Br., which is related to the East Indian tree, has a sp. gr. of from 0*958 to 0-972, optical rotation of 0-25 to 0*87, and refractive index 1*503 to 1*510. SANDARAGH A brittle, yellow gum-resin of a faint odour which exudes from a coniferous tree growing in Morocco and Barbary, named Thuja avticulata. It is soluble in alcohol and ether, and is used in varnish-making, etc. SANDSTONES Siliceous stones more or less ferruginous in character, used for building purposes. "SANXTAS " FLUID A product of the air-oxidation of terpenes in the presence of water, containing hydrogen dioxide, thymol, and some soluble resinous substances ; used as a non-poisonous oxidizing and bleaching agent, antiseptic and disinfectant. SANTONINE is a crystalline substance obtained from worm- seed (Semen contra, etc.), and about i per cent, has been found present in the leaves of Artemesia brentfolia, which grows in Cashmir and Western Thibet. It is insoluble in cold water, somewhat soluble in hot water, very soluble in hot alcohol, and is a useful remedy for worms in children, but has no destructive value against tape or thread worm. SAPONIFICATION A term given to the hydrolytic chemical action whereby fats and oils containing glycerides are converted into soaps. (See Esters, Fats, and Soaps.) SAPONIFICATION VALUE indicates the number of milli- grammes of potassium hydroxide required for the complete saponification of i gramme of an oil or fat. 424 SAPONIN SASSAFRAS OIL SAPONIN (formula sometimes given as C 32 H 52 O ir ) A nearly white inodorous glucoside of great foaming power. It is a constituent of common soapwort, Sarsaparilla quillaya, and alfalfa (lucerne hay), and otherwise widely diffused in the vegetable kingdom. Its dust excites sneez- ing, and when dissolved in water and agitated, it makes a frothy solution which is used as a foam-producer in the preparation of beverages, and for making emulsions with oils, etc. Commercial saponin is said to contain quillajic acid (C 19 H 30 10 ). (See Quillaya.) The saponin occurring in lucerne is stated to have the composition C 27 H 37 O 16 N, and is poisonous to fish, not by the exercise of any special toxic effect, but by preventing the diffusion of air into the water. The weak acidic nature of saponin is due to the presence of quillajic acid, which on boiling with weak acids is split up into glucose and insoluble quillajic sapongenin 2 C 19 H 30 10 + 8H 2 = 4 C 6 H 12 6 + C 14 H 28 4 . Saponins from quillaya bark yield about 31*1 per cent, sapogenin, and they are stated to consist of one-third quillajic acid and two-thirds of a body named sapotoxin. SAPPHIRE See Aluminium. SAPROPHYTES Minute organisms, including yeast cells and various bacteria, capable of inducing processes of fermen- tation. SARCINE or HYPOXANTfflNE (C 5 H 4 N 4 O) A weak basic body occurring in muscular flesh and nearly related to xanthine (CgH 4 N 4 O 2 ). Both substances are chemically related to uric acid. SARCOSINE (C 3 H 7 NO 2 ) A weak base obtained together with urea, by the action of baryta water on creatine C 4 H U N 3 3 = C 3 H 7 N0 2 + CH 4 N 2 (urea). SARDINE OIL See Fish Oils. SARSAPARILLA-ROOT (Smilax sarsaparilla, etc.) Contains, besides gum and starch, a peculiar substance known under several names, amongst others, sarsaparillin, which can be obtained in a crystalline form from an alcoholic extract of the root. It is very soluble in water and a decoction of the root is used in medicine and in compounding what is known as a " soft drink " in the United States of America. SASSAFRAS OIL A yellowish volatile oil distilled from the bark and root of Sassafras officinale L., having an odour like that of fennel oil. It has a sp. gr. of 1*065 to I<0 95> SASSAFRAS OILSCALES 425 SASSAFRAS OIL (Continued) optical rotation + i to + 4. It is soluble in alcohol and ether, contains safrol, eugenol, camphor, pinene, and phellan- drene, and is used in perfumery and medicine. (See Safrol.) SATINSPAR A fibrous form of gypsum (calcium sulphate). SATURATED COMPOUNDS are those in which there are no unsatisfied affinities for example, the normal hydro- carbons of which methane (CH 4 ) is typical. Methane is a saturated body, the tetravalency of carbon being fully satisfied by combination with four atoms of hydrogen. Again, phosphoric pentoxide (P 2 O5) is a saturated body, the 2 atoms of phosphorus (which is pentavalent) being satisfied by combination with 5 atoms of divalent oxygen. (See Unsaturated Compounds.) SATURATION The maximum degree to which a liquid can hold a solid in solution at any given temperature. Many substances are more soluble in hot liquids than in cold ones, and such hot solutions as they cool down to the ordinary temperature throw down or can be caused to deposit the excess of the dissolved body. (See Crystalliza- tion and Solution.) SAVIN OIL A nearly colourless, essential oil of sp/gr. 0*91 to 0*93 and optical rotation +40 to +60; soluble in alcohol and ether ; distilled from the twigs and leaves of Junipevus sabina of Northern Asia and North America. SCALES (Balances) for the determination of weights in chemical operations are made of great variety and some of extreme deli- cacy. The illustra- tion is that of one of Oertling's balances, carrying up to 200 grammes ; the beam turning with 0*1 milli- gramme. A new instrument, named the " Micro- scale," is stated to have been recently introduced which will register weights as small as three-millionths of a milligramme. 426 SCAMMONY SEA WEEDS SCAMMONY A purgative gum-resin produced by two species of convolvulus (Scamnionium) which grow in Asia Minor and Syria. The active principle is a substance of glucoside character resembling jalapin. SCANDIUM (Sc) Atomic weight, 44-1. A member of the cerium group and one of the rarest chemical elements; it is trivalent and forms the usual salts, including a colourless oxide (Sc 2 O 3 ), bromide (ScBr 3 ,3H 2 O), nitrate (Sc(N0 3 ) 3 . 4 H 2 0), and sulphate (Sc 2 (SO 4 ) 3 6H 2 O). The salts are colourless and soluble in water. Its discovery was predicted from a study of the periodic law of elements. (See p. 173.) SCAPOLITE A natural silicate of aluminium and calcium. SOHEELE'S GREEN Copper hydrogen arsenite (CuHAsO 3 ), an amorphous pulverulent pigment. SOHEELITE Natural calcium tungstate (CaWO 4 ), found in Arizona, Montana, New Mexico, and other United States an important source of the metal tungsten. SCHWEINFUET GREEN See Paris Green. SEAL OIL See Fish Oils. SEALING WAX A mixture made by heating together shellac, Venice turpentine, and vermilion (mercuric sulphide) ; another mixture is that of beeswax and rosin. Rosin (colophony) is often substituted in part for shellac, and various mineral colouring matters are used in place of vermilion according to the desired colour ; for white waxes basic nitrate of bismuth is used, giving a product of a beautiful white enamel-like brilliancy. SEA-WATER See Water. SEAWEEDS There are many species and abundant quantities, some of which are of considerable interest from a chemical point of view. Some kinds are burned for the sake of their alkaline ash and as a source of bromine and iodine, and others are used as articles of food and as fertilizing agents on account of the high percentage of nitrogen they contain. The ordinary sea-wrack is also said to be service- able for the production of a good paper pulp, but this has been contradicted. The amount of ash varies from 177 per cent, in F. sercatits to 52-37 per cent, in the roots of L. hyperboria. Laminaria sacckarina contains mannite and is largely used as food in China and Japan. Varec or vraic is greatly appreci- ated in the Channel Islands as a valuable fertilizer, and duft- weed is extensively used in Ireland as a dressing for potatoes. SEA WEEDS SELENI UM 427 SEAWEEDS (Continued) Rhodymenia palmata (dulse) and Alaria esculanta (murlins) are both used as food in the Scottish Highlands and Ireland. Chondrus cvispus (carrageen, or Irish moss) is sometimes used by painters instead of size, also for making jellies and mucilage. Gracilaria lichenoides (Ceylon or edible moss) is found in the Indian Archipelago and China and, together with Encheuma spinosum, is used for the preparation of nutrient jelly in bacteriological research, also for gumming silks, paper, etc., and for making soups. The protein content of seaweeds varies from 9-28 per cent, in Chondrus crispus to 29*06 per cent, in Porphym laciniata, and the nitrogen content from 1*485 to 4*65 per cent, both calculated on the dry matter. Seaweeds contain large proportions of gelatinous sub- stances from which nutritive jellies can be made, and a material prepared from them, is used to some extent as a substitute for horn, shell, whalebone, etc. A new crystalline sugar named flovidose has been recently obtained as a hydro- lytic product from the mucilaginous substance formed by boiling seaweed in water. (See Agar-Agar, Algin, Barilla, Kelp, and Salsola.) SELENITE A native hydrated calcium sulphate. (See Calcium.) SELENIUM (Se) and its Compounds Atomic weight, 79-2 ; melting-point, 217 C. ; boiling-point, 690 C. An element nearly resembling sulphur in its general properties, found in its free state ; also in combination with other metals in a number of minerals, and as selenide of sulphur in Swedish pyrites. It is recovered to some extent in the electrolytic refining of copper from the mud that settles in the cells and from the deposit that is thrown down from sulphuric acid in the chambers and Glover tower. Like sulphur it is allotropic, three varieties at least being known viz., a vitreous red form, of sp. gr. 4-3, obtained by precipitation ; a crystalline red form, of sp. gr. 4-45, and the dark grey or black metallic form which melts at 219 C., and is of sp. gr. 4- 80. Of these, the two first named are soluble in carbon disulphide. The amorphous form is a bad conductor of heat and electricity, while the crystalline metallic variety is a good conductor, is insoluble in carbon disulphide, and its electrical conductivity is increased by the agency of light. Heated in the air, it burns with a blue flame, forming an oxide and emitting an offensive pungent odour. 428 SELENIUMSERALBUMIN SELENIUM (Continued) Selenium is used in wireless telephony, electrical and physical contrivances, in photometry, and advantage is taken of its peculiar electrical conductivity when exposed to light in the construction of an instrument termed the "optophone," by means of which the blind can read books through the agency of the telephone. Two oxides apparently exist, but only the dioxide (SeO 2 ) is well established, and is a white crystalline body which can be sublimated, and dissolves in water to form selenious acid (SeH 2 O 3 ) corresponding to sulphurous acid. There is also a selenic acid (SeH 2 O 4 ) corresponding to sulphuric acid. Two chlorides are known viz., Se 2 Q 2 , a brown oily compound which has the property of dissolving metallic selenium, and which is slowly decomposed by water, and SeCl 4 , which is a white crystalline volatile substance. Hydrogen Selenide (SeH 2 ) is a colourless gas resembling hydrogen sulphide in its odour and chemical properties, obtained by the action of an acid upon a selenide. The compounds of selenium resemble those of tellurium in most respects. "SEMI-STEEL," S.P.M. A material possessing mechanical properties intermediate between those of cast iron and cast steel, of which filter-press plates and some autoclaves are constructed. SEMOLINA A farinaceous preparation made from the hard grain wheats of Italy, Spain, and South Russia, containing a relatively large amount of nitrogenous material. SENEGAL GUM See Gums. SENNA A purgative drug made of the leaves of the shrub Cassia acutifolia, or Cassia angustifolia, which grow in parts of Abyssinia, Barbary, Egypt, Tripoli, the East Indies, and Syria. It contains a number of chemical principles, one of which is named cathartin. An infusion of the leaves makes a useful cathartic. "SENSITOL" (Green and Red) Two substances of dyestufi character used in the production of panchromatic photo- graphs. SEPIA See Cuttle Fish. SEPTIC POISONS Toxic chemical products produced by bacteria as in wounds. (See Bacteria, Microbes, Ptomaines, Putrefaction, and Pus.) SERALBUMIN Serum albumin. (See Albumins, Proteins, and Serum.) SERPENTINE SE WA GE 429 SERPENTINE Mineral forms of hydrated magnesium silicate. Some contain alumina and others are free from that association. SERUM That part of the blood solution which remains liquid after coagulation, the coagulation of the fibrin entangling in its meshes or " clot " the corpuscles of the blood. It contains a kind of albumin called seralbumin and some salts. The seralbumin is completely separated or coagu- lated by adding a little acetic acid and boiling. The liquid which forms in a blister is a familiar example of serum. SESAME OIL A fatty non-drying oil expressed from the seeds of Sesamum ovientale (indigenous in India) containing olein, stearin, palmitin, etc. Its sp. gr. is 0*921 to 0*925 ; it melts at 26 to 32 C. ; iodine value, 103 to 114; saponification value, 1 88 to 193 ; and refractive index, 1*457. It is soluble in ether and carbon disulphide, and is used for burning in lamps, for soap-making, and as an article of food. SEWAGE The treatment or disposal of sewage necessarily varies with the quantity and quality to be dealt with. Small quantities can be readily disposed of without other treatment by irrigation that is, distribution over land where sufficient is available, in which case the natural processes of hydrolysis, nitrification, and oxidation rapidly convert the organic constituents into harmless and vegeto- nutrifying products. In moderate- sized areas, as in all large ones, water is employed as the collecting carrier, and in these cases, after sedimentation in collecting tanks with or without chemical treatment, the effluent can, as a rule, be distributed over land, or carried into running rivers or out to sea where that disposal is available. The chemical treatment in such cases depends upon the character of the sewage and the trades refuse that may form part of it. Sometimes milk of lime is used ; in others, ferrous sulphate or sodium man- ganate ; and in yet others, powdered coke or breeze or dried peat can be used, the precipitated sediment being disposed of by digging into land, or pressed and used as manurial dressing, or alternatively carried as sludge, containing some 85 per cent, water, away to sea. For large towns and cities, the purification of sewage has of late been carried out in two stages, the first of which employs treatment in what is known as the "septic tank," through which the sewage passes slowly, and in which the solid parts fall to the bottom and are attacked by anaerobic organisms, thus being ultimately liquefied or turned into 430 SEWAGE SHELLAC SEWAGE (Continued) gaseous products. In the second stage, the dissolved impurities are disposed of by oxidation, a process which is effected by passing the liquid over a large specially con- structed filter or " contact" bed, or alternatively over land. Where suitable land in sufficient quantity is not available, the artificial filters are made of broken clinker or coke, in which the nitrifying bacteria carry out the required purification. More recently, the so-called " activated sludge " process has been introduced, in which the whole purification is completed in a tank charged with a quantity of activated sludge to serve as concentrated carrier of the nitrifying bacteria upon which the purification is dependent, the charge of sewage being subjected to a current of air for several days. After the bacterial digestion is completed, the sludge can be pumped, as at Birmingham, over shallow ash-beds, when it readily parts with its water by filtration, without offence. It is stated that when crude sewage is passed through a filter bed of straw, the soluble nitrogen compounds are removed from it, so that the effluent becomes comparatively harmless, and the straw itself is thus converted into a valuable manure. (See Microbes and Nitrification.) SHALE A fine-grained rock of silt or clay with a cleavage like that of slate. It occurs in quantity in Scotland and elsewhere and is often of bituminous or petroleum oil- bearing character. Deposits have recently been found in Derbyshire, Norfolk and Notts. SHALE OIL A sort of petroleum oil obtained by destructive distillation of shale (schist) found as a natural deposit in Scotland and elsewhere, ammonium sulphate being obtained as a by-product. (See Petroleum and Naphtha.) SHARK OIL See Fish Oils. SHEA BUTTER A greenish-white solid vegetable fat from the nuts of Bassia parkii (West Africa), containing oleic and stearic acids. It has a sp. gr. of 0-9175, a saponifica- tion value of 179 to 192, and an iodine value of 56-6. SHELLAC " Stick lac " is the lac insect (Coccus lacca) which abounds in the forests of Assam and the resinous covering which it forms on the branches of the trees upon which it is found. From it, is prepared "seed lac" that is, lac from which the wood has been removed. Lac dye is the colouring matter of the insect, and shellac is the resin pre- SHELLA C SILICON 431 SHELLAC (Continued) pared by melting and straining. Shellac is used in leather- dressing and making varnishes and sealing wax. (See Lacquer and Sealing Wax.) SICCATIVES Agents which promote drying, more particularly applied to so-called " driers " used in connection with varnishes, oils, and paints, such as manganese borate and manganese resinate. (See Linseed Oil, Paints, and Varnishes.) SIDERITE (Spathic Iron Ore) A mineral carbonate of copper (FeCO 3 ). SIENNA A yellowish clay coloured by metallic oxides (iron and manganese), used as a pigment. SILAGE A fermentation product used as cattle food, made from green fodder (such as oats and tares, grass and maize), which is cut up and stored in such wise that acetic acid is produced and acts as a preservative. SILICA See Clays, Silicon, and Zeolites. SILICATE OF SODA See Silicon. SILICIC ACID See Silicon. SILICON (Si) and its Compounds Atomic weight, 28 ; melting- point, 1,420 C. Silicon compounds are abundant and widely distributed in nature. It is not a metal, but it is known both in the forms of a brown powder and in a crystalline condition of metal-like appearance. Combined with oxygen as silica (SiO 2 ), it is found in the forms of flint, sand, quartz, rock crystal, agate, amethyst, jasper, chalcedony, christobalite, and tridymite. In other combinations, it helps to make up* the composition of clay, soil, and many rocks. (See Clay and Zeolites.) Silica occurs in nature, also, in combination with water (SiO 2 3H 2 O) in the forms of opals and kieselguhr. To obtain silicon in the free state, several processes are available, in one of which, a mixture of potassium-silico- fluoride and metallic potassium is strongly heated, when the potassium replaces the silicon which is thus set free and obtained by dissolving out the potassium fluoride with water : As thus prepared it is a dark brown amorphous powder with a sp. gr. of 2'i^. Silicon is obtained in needle-shaped crystalline form by fusing a similar mixture (or replacing the metallic potassium 432 SILICON SILICON (Continued) with metallic sodium) with a proportion of metallic zinc, the crystallized silicon being deposited on the zinc, which can be subsequently dissolved out by acid treatment. In this form, the silicon is hard enough to scratch glass, has a sp. gr. of about 2-34 to 2-49, and is very insoluble in acids. Exposed to a higher temperature in vacuo it becomes still denser and attains a sp. gr. of 3. Another process consists in heating quartz with wood charcoal, lime, and manganese oxide in an electric furnace. Silicon is insoluble in water, hydrochloric and nitric acids, but soluble in hydrofluoric acid and alkalies. Two compounds of silicon with hydrogen are known viz., silicon hydride (SiH 4 ), a colourless gas which is decomposed by alkaline hydrates, giving the corresponding silicates and evolving hydrogen SiH 4 + 2 NaHO + H 2 O - SiO(NaO) 2 + 4 H 2 , and liquid silicon hydride (Si 2 H 6 ), a colourless mobile liquid which is spontaneously inflammable in the air. These compounds, known as silanes, are obtained by the action of acid on magnesium silicide. Quartz crystals find uses not only as gems, but also for certain optical purposes; while sodium silicate (Na 2 SiO 3 ) in the form of solution (water-glass), is largely used for fire- proofing fabrics, in making concrete hardeners, as a filling for soap, etc. It is also sometimes employed for preserving stone facings of buildings from atmospheric attack. To understand this last-named application, it may be explained that many stone buildings are composed of natural lime- stone (CaCO 3 ), and the carbon dioxide and water which are always present in the air have a destructive solvent action upon such facings. (See Calcium.) This can be prevented to some extent by washing with sodium silicate, as the silica enters into combination with the calcium of the limestone, forming on the surface a thin layer or coating of calcium silicate which is not subject to the same destructive influence Water-glass in solution is also largely used in the pre- servation of eggs, the egg-shells being made air-tight by coating their surfaces with it, thus preventing the access of air-borne germs. Sodium silicate is prepared by calcining a mixture of quartz, soda carbonate, and powdered coal, and extracting the molten mass with water, etc. Silicon Dioxide or Silica (SiO 2 ) may be prepared in the laboratory in crystalline form or as a white powder by a SILICON AND ITS COMPOUNDS 433 SILICON (Continued) variety of methods, as when, for example, amorphous silicon is burned in the air. It is fusible in the oxy- hydrogen flame, when it melts to a transparent glass- like mass. I*t is insoluble in water, and the only acid that will dissolve it is hydrofluoric acid ; it is, however, soluble in alkalies. When fused silica is heated above 1,000 C. it is trans- formed gradually into christobalite a change which is completed in several hours after continuing the heat to 1,500 C., and the final product is stated to be probably tridymite. Quartz begins to soften at about 1,650 C., and becomes a viscous fluid at 1,750 to 1,800 C. Silica is stated to be strongly volatile at a temperature slightly above its melting-point, and its use as a substitute for glass is a developing industry, being acid-proof, abraded with difficulty, and exhibiting great resistance to tempera- ture shocks. Silica glass is absolutely insoluble in boiling water, but is permeable to gases at high temperatures, and is an ideal electrical insulating material. (See Vitreosil.) The enormous quantities of siliceous "sinter" deposited by the geysers at Rotomahama in New Zealand and else- where, are formed by the action of atmospheric carbon dioxide upon alkaline silicates held in solution by the hot springs, the silicates being decomposed, thereby causing the deposition of the silica and the re-formation of an alkaline carbonate. Silicic Acid (Si(HO) 4 ) is the best-known member of several weak acids which are formed by combination of silicon dioxide with water, and can be obtained either in solution or in a gelatinous form, in both of which it behaves as a colloid. Combinations in the nature of silicates form a large number of minerals, many of which are very complex in composition ; amongst the more simple ones may be enumerated : serpentine, a magnesium silicate of formula Mg 3 Si 2 O 7 ; felspar, with the composition Al 2 K 2 (Si 3 O 8 ) a ; and pendote, Mg 2 SiO 4 (magnesium silicate). Silicon Fluoride (SiF 4 ) is a colourless, fuming gas pre- pared by the action of sulphuric acid upon powdered fluor- spar and white sand 2 CaF 2 + 2 H 2 S0 4 + Si0 2 = 2 CaSO 4 + 2H 2 O + SiF 4 . The same compound is formed direct by bringing silicon into contact with fluorine when it takes fire. The 28 434 SILICON-SILK SILICON (Continued) gas can be liquefied to a clear colourless state, and when brought into contact with water, decomposition takes place, dibasic silicic acid being precipitated as a gelatinous mass accompanied with hydrofluosilicic acid in solution 3SiF 4 + 3H 2 O - 2H 2 SiF 6 + H 2 SiO 3 . Hydrofluosilicic Acid (H 2 SiF 6 ) can also be obtained as a colourless fuming liquid by distilling the gaseous silicon tetrafluoride with water. It is very corrosive and is employed in the ceramic industries and in making concrete floors and certain technical paints. Silicon Tetrachloride (SiCl 4 ) is produced when silicon is strongly heated in a current of chlorine. The silicon burns and the tetrachloride is formed direct ; or it can be made by passing chlorine gas over a mixture of silica and carbon (silicon carbide) in an electric furnace, when the following change takes place : SiO 2 + 2C + 2C1 2 = 2 CO + SiCl 4 that is to say, the tetrachloride is produced, attended with the formation of carbon monoxide. The gas can be con- densed by cooling and is then a colourless liquid which fumes in the air, and is decomposed by water into silicic and hydrochloric acids. It was used in the Great War for producing smoke screens. Silicon unites with aluminium, iron, zinc, copper, calcium, magnesium, and some other metals, forming compounds named silicides. It also unites with carbon to form the hard crystalline substance named carbonmdum, and enters fundamentally into the composition of various kinds of glass which are, in reality, insoluble compound silicates. Silicon bronze is an alloy of silicon, copper, and tin used for telegraph and telephone wires. Silicon acts as a substitute for carbon in many organic compounds, and among these are tetramethyl silicane or silicon methyl (Si(CH 3 ) 4 ), a mobile liquid of light nature, and tetra-ethyl silicane or silicon ethyl (Si(C 2 H 5 ) 4 ), both of which burn with a bright cloud and emit white clouds of silica. (See also Glass, Carborundum, Ferro-alloys, and Iron.) SILK The fibrous material in which the silkworm envelops itself before passing into the chrysalis state, named sericin SILK SILVER 435 SILK (Continued) QIC fibroin. This is coated with a kind of wax which has to be removed in the process of silk-dyeing. Silk is nearly allied to but not absolutely identical with cellulose. (See Cellulose.) SILK (Artificial) All artificial silks are made from cellulose, and so-called mercerized cotton is practically a simple form of artificial silk. (See Mercerization.) Thiele silk, which is a French production of long standing, was made by dissolving cellulose in ammoniacal cupric oxide solution and forcing the solution through small holes into dilute acid, but the great advance made in more recent times has resulted from new investigations. Mercerized cellulose prepared from wood-pulp is acted upon by carbon di- sulphide, thus producing a swollen yellowish mass consisting of the sodium salt of cellulose xanthate which is sub- sequently dissolved in water and treated with acid, thus effecting the reprecipitation of the cellulose as a gelatinous mass to which the name of *' viscose " has been given. It is this product, or that prepared from other cellulose fibres by solution in dilute alkali and projection through fine apertures into a coagulating medium of sulphuric acid or other solution, which, after some purification, is used in the manufacture of artificial silk. This is made by drawing the coagulated viscose on to bobbins, then washing, drying, and weaving as required. Viscose dries to a hard, horn-like mass and is also employed as a substitute for articles resembling celluloid and ivory, and when mixed with zinc oxide or clay it makes a hard substance called viscoid. Artificial Silk is stated to have a greater affinity for dye- stuffs than cotton, and unevenness in shade is occasionally observed in the dyed material, but recent investigations have provided a way for overcoming this difficulty. SILVER (Argentum, Ag) and its Compounds Atomic weight, 108; sp. gr., 10-5; melting-point, 960-5 C. Silver occurs in nature in the metallic state and in combination in a number of minerals, including argentite or silver glance (as silver sulphide (Ag 2 S)), in horn silver (as chloride (AgCl)), and as silver sulphide associated with other metallic sulphides mpyrargyrite (Ag 3 SbS 3 ), stephanite (Ag 5 SbS 4 ), and proustite (Ag 3 AsS 3 ). The world's supply comes from the United States of America, Canada, Mexico, South America, and Japan. To obtain metallic silver from galena containing it, resort is had to the process described as cupellation, which depends 436 SILVER AND ITS COMPOUNDS SILVER (Continued} upon the fact that the silver can be concentrated into a small portion of lead by crystallization, and then the mixture is exposed to a strong blast of air, thus oxidizing the lead into litharge (PbO), which fuses and runs away or is absorbed by the porous bed of the furnace, leaving the silver behind. The furnace bed is made of bone ash so as to be absorbent, and is known as a cupel. The crude silver as prepared fromi its sources, is purified in another process, by amalgamation with mercury, followed by distilling off the mercury, which leaves the refined silver behind; and there are a number of other methods which are adapted to the several requirements according to the composition of the ore from which the silver has to be obtained. Silver is a white metal which is not acted upon by the oxygen of the air ; it is soluble in nitric acid and is tarnished when sulphuretted hydrogen is present in the atmosphere, due to the surface formation of silver sulphide. Silver articles deliberately coloured in this way are com- monly but erroneously described as " oxidized " silver. It is the best metallic conductor of heat and electricity, very malleable and ductile, and, alloyed with copper, it is largely used for coinage and other purposes, including jewellery and electro-plating. Until recently the British standard for coin was 92^ per cent, silver and 7^ per cent, copper, pure silver being too soft to use alone for this purpose. (For Electro- Plating, see Electricity, p. 166.) Silver forms several oxides insoluble in water, including a black suboxide (Ag 4 O) and the monoxide (Ag 2 O), the last named being produced by the addition of an'alkaline hydroxide solution to one of silver nitrate. It also is black, and when dried and heated to 260 C. gives off oxygen and is reduced to the metallic state. It is soluble in strong ammonia, and the solution, on standing, deposits black shining crystals of what is known as fulminating silver, an explosive compound believed to be the nitride Ag 2 N. Silver Chloride (AgCl) is white, and insoluble in water, but soluble in ammonia. Silver Bromide (AgBr) is pale yellow and less soluble in ammonia, but is soluble hi solutions of potassium bromide and cyanide. Silver Iodide (Agl) is yellowish, still less soluble in ammonia, but the most stable of the three halogen com- pounds. SIL VERSKA TOLE 437 SILVER (Continued) Silver Nitrate (lunar caustic) (AgNOg) is made by melting the crystals of that compound at about 218 C. It is the most important soluble silver compound as, apart from its use in photography, it is used medicinally as a caustic application, also in silver plating and in the manufacture of an indelible ink for marking linen, etc. It crystallizes in large rhombic tables, is very soluble in water, is decomposed at a red heat, giving off oxygen, and is wholly decomposed at a higher temperature, leaving the metal as a residue. Silver Sulphide (Ag 2 S) is formed as a black precipitate by passing hydrogen sulphide gas through solutions of silver salts, and it occurs naturally in the form of silver glance. It is used in inlaying in niello metal work. Silver Potassium Cyanide (KAg(CN) 2 ) is a white crystal- line, soluble in water and used in silver plating, etc. Many of the silver compounds are used in photography, and as the chloride is soluble in sodium hyposulphite, that reagent is extensively used for " fixing " purposes that is, dissolving out the silver compound that has not been decomposed by the actinic rays. SINAPINE An organic base of alkaloidal character contained in white mustard seed. (See Mustard.) SINTER Incrustation on rocks, etc., deposited from mineral waters. (See Silicon, p. 433.) SIPHONS Appliances for drawing off (siphoning) fluids from one vessel to another. SISAL HEMP (for twine-making, etc.) is obtained from a plant (Agave rigida) growing in Central America and the West Indies and now cultivated on an extensive scale in some parts of East Africa, and is said to be more popular with spinners than Mexican henequen. Ordinary hemp comes from the plant Cannabis sativa, a native of India, and is cultivated extensively in other countries. (See Hempseed Oil.) SIZE A gelatinous body, being an undried form of glue, prepared as a jelly from the third extraction of bones in the making of glue. SKATOLE (C 9 H 9 N) A crystalline substance found amongst the products of the putrefactive decay of albuminous sub- stances, also in faeces ; it melts at 95 C. SLAG SLAG (Basic Slag) Cinder from blast-furnaces consisting largely of silicates of calcium and aluminium, containing also phosphates in considerable proportion. When reduced to powder it is largely used as a phosphatic fertilizing material for agricultural purposes and in making cement. (See Iron.) The phosphide of iron (Fe 2 P) representing the state of combination in which the phosphorus exists in molten iron is oxidized by reactions of the type 5Fe 3 O 4 + 2P = 15FeO + P 2 O 5 and 5Fe 3 O 4 + 8P = 15Fe + 4P 2 O 5 . The P 2 O 5 may combine' with FeO to form Fe 3 (PO 4 ) 2 , but as this is unstable in the presence of a large excess of iron, a reaction such as Fe 3 (PO 4 ) 2 + 1 1 Fe = 8FeO + 2Fe 3 P results, and it is in consequence of this change, that the acid process of steel -making is unable to remove phosphorus. In the basic process, the presence of lime causes the formation of phosphate by .the change indicated by the reaction Fe 3 (PO 4 ) 2 + 4CaO = Ca 4 P 2 O 9 + 3FeO. The calcium phosphate thus formed is only feebly attacked by the metallic iron, but manganese and carbon act more vigorously and cause the phosphoric acid to be reduced and the metal to be rephosphorized, a tendency which is re- strained, however, by maintaining a certain concentration of ferrous oxide. The high reputation basic slag from the Bessemer process has acquired for the improvement of poor pastures is said to be indirect and to result from a stimulation of the white clover, although it is not definitely known whether the action of the phosphate is on the clover-plant or on the nodule organism. It contains from 16 to 20 per cent, phosphoric acid in combination with lime, etc. The new so-called basic, open-hearth process gives two qualities of slag, both of which are poorer in phosphates and contain on average from 9 to 13 per cent, phosphoric acid in combination. One is made by a process involving the use of calcium fluoride, and is consequently less soluble than the other, whereas that made without fluorspar is as effective as the old Bessemer slag when compared on the SLAG SOAPS 439 SLAG (Continued) basis of equal amounts of phosphorus content. The demand for basic slag is so great that it is computed British agriculturists could absorb as much as three to four hundred thousands of tons per annum if available. In certain experiments made at Cockle Park, untreated pasture yielded about 20 Ib. of lean meat per acre per annum, whereas after treatment with slag the yield rose to 105 Ib. of meat per acre. Moreover, after eleven years' treatment with basic slag the percentage of nitrogen in the soil increased from 0-185 to 0-286 per cent. a gain of about 850 Ib. per acre. The slag preferred for agricultural dressing is ground sufficiently fine to allow 80 per cent, of the total weight to pass through a sieve having 10,000 apertures to the square inch. The value of commercial deliveries in the past, has not been based upon the phosphate total content, but upon that portion of it which is soluble in a 2 per cent, solution of citric acid under certain prescribed conditions formulated by the Board of Agriculture. It has, however, been recently pointed out that the slag varies in quality so enormously that the proportion of phosphate dissolved by 2 per cent, citric acid solution also greatly varies viz., from about 6 to 29 per cent. showing that this test and the total phosphate content is not sufficient to afford reliable information of the fertilizing values of different qualities of basic slag. The essential fertilizing con- stituents of slags is a matter of some doubt, and by some it is considered likely that the silico-phosphates are the most valuable. The annual output of slag phosphate in the United Kingdom is about 400,000 tons. SLAG WOOL See Iron. SLATE A mineral form of silicate of aluminium and mag- nesium a kind of argillaceous (clay-like) rock. SMALT See Cobalt. SMALTINE See Cobalt. SMITHSONITE A mineral carbonate of zinc (ZnCO 3 ). SOAPS Combinations or salts of fatty acids with alkali, including hard, soft, silicated, and resinated varieties. Hard Soaps are manufactured from the harder fats, such as tallow, palm oil, cocoa-nut oil, etc., with or without the. 440 SOAPS SOAPS (Continued) addition of rosin (which also combines with alkali) by boiling with caustic soda lye of sp. gr. 1*05, the soap being afterwards " salted " out by the addition of common salt, which renders it insoluble. After withdrawing the spent lye from which glycerine is obtained (see p. 231), the soap is solidified in rectangular iron frames and after hardening (drying) by keeping, is cut up into slabs and bars by means of wires. Silicated Soaps are otherwise ordinary soaps into which a proportion of an alkaline silicate is introduced, as these substances, like soaps, have the property of liberating alkali when dissolved in water. The sodium silicate is prepared by fluxing clean sand and soda ash (sodium carbonate) in certain proportions, and for the potassium silicate used for incorporation with soft soaps, potassium carbonate is substituted for the soda ash. Mottled Soaps are produced by adding to the nearly finished hard soap mass, crude soda liquor containing some sodium sulphide, from a water-pot. In this way, any iron that may be present in the soap combines with the sulphur of the sulphide to form iron sulphide, which makes its appearance in streaks or veins. In some cases, a little ferrous sulphate is added to the soap during the boiling and this becomes decomposed, forming first of all ferrous oxide and then ferric oxide, thus mottling the soap in a marked degree. Again, in other cases, the mottling is produced by the addition of Prussian blue ; but mottling is only an old trade practice and serves no useful purpose. Soft Soaps are made chiefly from linseed, castor, and other seed and fish oils, tallow or resin being, at times, in- corporated in certain proportions for stiffening purposes, and potash lye being used as the saponifying agent. In some cases, the glycerine is left in the soap, which is heated and stirred until it "talks," and during which operation much of the water is evaporated, after which it is ready for packing. In other cases the glycerine is removed from the soap by chemical processes. Toilet Soaps are made of hard soap suitably moulded into tablets, and may be perfumed or impregnated with any desired substance. The transparent character of certain varieties is obtained by the addition of sugar, honey, or alcohol. Hard soaps contain from u to 69 per cent, of fat SOAPS SO DA -OLE IN " 441 SOAPS (Continued) acids, the best qualities containing about 62 per cent, and upwards. Soft soaps contain from 40 to 45 per cent, fat acids, and good toilet soaps from 60 to 70 per cent. From a recent investigation P. J. Fryer concludes that " the velocity of saponification of oils and fats, from the point of view of the amount of free alkali removed from the reacting solution, is in inverse ratio to the saponification equivalent or to the mean molecular weight of fatty acids" of their glycerides. The detergent action of soap is chiefly attributable to its power of dissolving and emulsifying oil (including paraffin oil), thus producing soluble compounds or emulsified mixtures readily removable by water. Soap solutions possess a high degree of electrical con- ductivity both in dilute and concentrated solutions. SOAP-STONE (steatite French chalk) is composed chiefly of talc or a native form of magnesium silicate. SOAPWORT See Saponin. SOBREROL (C 10 H 16 (OH) 2 ) A crystalline compound formed when pinene (a terpene) is left exposed to sunlight in contact with air and water. SODA See Sodium. SOD AMIDE (NH 2 Na) is obtained by passing dry ammonia gas over molten sodium in the absence of air. It is a powerful dehydrating agent, which finds use is the synthetic produc- tion of indigo from aniline. SODA ASH Crude sodium carbonate. SODA-LIME A laboratory reagent sometimes used in making nitrogen determinations in organic analyses, and employed for the absorption of various acid gases, such as phosgene, in military operations. It consists of caustic soda and quick- lime, and is made by moistening a mixture of the two ingredients with a solution of caustic soda and drying the mixture. SODA NITRE See Sodium. "SODA-OLEIN" A commercial preparation in the nature of sulphonated castor oil. 442 SODIUM AND ITS COMPOUNDS SODIUM (Natrium, Na) and its Compounds Atomic weight, 23 ; sp. gr., o'97 ; melting-point, 97*5 C. Sodium, like potas- sium, is one of the alkali group of metals, and its chloride is best known as a constituent of sea- water, which contains an average of about 28 parts per 1,000. Sodium chloride (NaCl), or common salt, also occurs naturally in large deposits in Cheshire, Lancashire, and else- where, whilst sodium nitrate (NaNO 3 ) is the principal constituent of caliche or soda nitre, which is found in large quantities in Chili and Peru and which is exported to the extent of some two million tons annually, having great value as a fertilizing agent on account of its richness in nitrogen. In the purified state, salt forms a very valuable food for men and animals. At Lake Magadi in British East Africa there exists a remarkable deposit of natural crystalline sesquicarbonate of soda of vast extent, stated to contain 200 million tons of soda free from sulphur impurities. It is stated to contain sodium salts to the extent of 40*38 per cent, when calculated as Na 2 O, and which upon the calcined product would amount to 58*08 per cent., or 99-3 per cent, dry soda ash (NajjCOg). Metallic sodium is now made in large quantity by the electrolysis of fused caustic soda at a temperature of about 20 C. above its melting-point, or by the electrolysis of fused sodium chloride, using a cathode of molten lead, and subsequent electrolysis of the sodium-lead alloy thus pro- duced. It is used largely in other manufactures, including that of indigotine as prepared synthetically. Metallic sodium is very like potassium in most respects, being soft and silver-white, and decomposing water with considerable violence on being thrown into it The Na 2 O, or sodium oxide, thus formed dissolves in the excess of water and forms sodium hydrate (hydroxide) or caustic soda (NaHO) solution. The pure oxide is formed when metallic sodium is exposed to dry air at a low temperature. It is white, amorphous, and has a great avidity for water. Caustic Soda (NaHO) is largely manufactured for use in many chemical applications, especially in the making of soap, being capable of decomposing fats and oils, thus liberating SODIUM AND ITS COMPOUNDS 443 SODIUM (Continued) glycerine, and combining with the fatty acids (their other constituents). (See Soaps.) Much of the caustic soda that is manufactured is still made indirectly from common salt by various chemical processes, and in particular by treatment of the derived crude sodium carbonate with lime, the liquors being thus " causticized " and attended with the production of calcium carbonate as a by-product. The causticized liquor is then evaporated down to a state of fusion. An increasingly large amount, however, is now commercially made by processes of electrolysis direct from brine or strong solu- tion of common salt (NaCl) in water. Caustic soda is a white, highly deliquescent, caustic substance, and is marketed in several forms and of varying degrees of purity and strength, suited to its several applications. These include a liquor form of 90 Tw. strength ; solid forms of from 60 to 76 per cent. ; powder form of from 77 to 78 per cent, (in terms of Na 2 O) ; a crude form containing from 40 to 42 per cent. ; and a still cruder form styled " bottoms." Sodium Peroxide (Na 2 O 2 ) results from the burning of metallic sodium in oxygen. It is a nearly white substance of considerable commercial importance, owing to the fact that in contact with water or dilute acids it decomposes, yielding hydrogen peroxide in solution : Na 2 2 + 2HC1 = 2NaCl + H 2 O 2 . It is consequently used as a bleaching agent for wool, silk, yarn, and various fibres, and in the straw-hat and other industries. It is commercially made by passing purified dry air over metallic sodium placed on trays of aluminium at a temperature of 300 C. Sodium Carbonate (Na 2 CO 3 ) is extensively used in glass manufacture, and is the basis of washing-soda (soda crystals, Na 2 CO 3 ioH 2 O), which is so largely employed for detergent and cleansing purposes,, and this compound in its several commercial forms is also obtained from common salt by a number of chemical processes. When common salt (NaCl) is subjected to the action of strong sulphuric acid at a temperature of about 120 F., it is resolved into sodium sulphate and hydrochloric acid gas which can be subsequently condensed and dissolved 444 SODIUM AND ITS COMPOUNDS SODIUM (Continue^ by the action of water. In the so-called Leblanc process, crude sodium carbonate is made by furnacing sodium sulphate (produced as above described) with chalk or limestone or lime and small coal, when a number of chemical changes take place of which a general view is indicated by the equation : Na 2 SO 4 + 2C + CaCO 3 = CaS + 2CO 2 + Na 2 CO 3 , calcium sulphide being formed together with the carbonate of sodium which is afterwards dissolved out of the fluxed mass with water and purified. (See Alkali Trade, p. 18.) Soda crystals effloresce or give up water when exposed to the air, the crystals falling to powder having the com- position Na 2 CO 3 H 2 O. A carbonate can be obtained in rhombic crystals by crystallization from hot solutions with the composition Na 2 CO 3 ,7H 2 O. This is a soluble salt, 100 parts water dissolving 59 parts at 32*5 C. Sodium hydrogen carbonate or so-called bicarbonate (NaHCO 3 ) is obtained commercially by the ammonia-soda process, but can be made by the action of carbon dioxide upon the ordinary carbonate Na 2 CO 3 , ioH 2 + CO 2 = 2 NaHCO 3 + 9H 2 O. There is also a so-called sesquicarbonate of sodium which occurs in Egypt and elsewhere as a natural deposit, having the composition expressed by the formula Na 2 CO 3 , 2NaHC0 3 ,2H 2 0. Large quantities of sodium carbonate are now made by the ammonia process, in which sodium chloride and hydrogen ammonia carbonate (ammonium bicarbonate) are made to interact in such a way as to result in the formation of ammonium chloride and hydrogen sodium carbonate. (NH 4 )HCO 3 + NaCl = NaHCO 3 + NH 4 C1. In this process, a brine solution is saturated with ammonia gas, and the liquid is then charged with carbon dioxide gas; the sodium bicarbonate thus produced, being but slightly soluble in cold water, separates out, and is con- verted into the normal carbonate by calcination. The ammonium chloride, which is more soluble, remains in solution, and the ammonia is afterwards recovered from it by the action of lime 2 NH 4 C1 + CaH 2 2 - CaCl 2 + 2 N H 4 HO. SODIUM AND ITS COMPOUNDS 445 SODIUM (Continued) Sodium carbonate is also manufactured on a large scale by a process involving the electrolysis of a strong solution of brine (common salt), which produces chlorine at the anode and generates sodium hydroxide at the cathode. The solution of sodium hydroxide can be evap- orated to dryness, thus furnishing solid caustic soda, or made to encounter a stream of steam and carbon dioxide, and thus converted into sodium carbonate, which is washed away in solution and concentrated by heat to the point of crystallization. The chlorine generated as above described is utilized in the manufacture of bleaching-powder or con- densed and liquefied. Apart from the uses of sodium carbonate already noted, it is largely employed in the manufacture of soaps, metal- lurgy, as a flux, and in the leather trade. Sodium Bicarbonate is largely used in compounding effer- vescent salts, artificial mineral waters, baking-powders, and in many industries. Sodium Sulphate (Na 2 SO 4 ) is found naturally in the form of the mineral thenardite, whilst glaubevite is a double sulphate of sodium and calcium. Apart from its incidental manufacture in the alkali trade as so-called salt-cake, it is obtained from Stassfurt salts by interaction between magnesium sulphate and sodium chloride 2NaCl + MgSO 4 = Na 2 SO 4 + MgCl 2 . It is a highly soluble salt which crystallizes with 10 mole- cules of water (Na 2 SO 4 ,ioH 2 O), is efflorescent, and melts in its own water of crystallization when heated to 33 C. By more exposure to the air, it gradually loses all its water, and is then known as "desiccated Glauber's salts." It has medicinal value as a purgative. Sodium Hydrogen Sulphate (NaHSO 4 ), known also as "bisulphate"and "nitre-cake," was produced on an immense scale during the recent war as a by-product in the manu- facture of nitric acid which is generally not pushed be- yond the first stage, as represented (see p. 337) by the equation NaN0 3 + H 2 SO 4 = NaHS0 4 + HNO 3 , and it became a matter of considerable importance to devise means of utilizing this residual substance containing the equivalent of a mixture of 30 per cent, sulphuric acid 446 SODIUM AND ITS COMPOUNDS SODIUM (Continued) and 70 per cent, of sodium sulphate. Of these, there are two methods which may be here referred to. In the one, ammonia gas is passed into a heated solution of the nitre- cake containing a proportion of sulphuric acid, and after saturation, the bulk of the sodium sulphate (Na 2 SO 4 ) thus produced, is crystallized out, leaving ammonium sulphate in the mother-liquor, from which it can be obtained by crystal- lization or evaporation to dryness. In other words, the acid sodium sulphate (sodium hydrogen sulphate) is thus converted into the normal sulphate, ammonium sulphate being simultaneously produced 2NaHS0 4 +2NH 3 = Na 2 S0 4 +(NH 4 ) 2 S0 4 . The other method consists in dissolving gafsa phosphate in a solution of nitre-cake, 100 parts of the phosphate (59 per cent, strength) requiring about 184 parts of the nitre-cake to furnish the required amount of SO 3 ; 44*63 parts of water being used and subsequently increased by a further 10 per cent. The product thus obtained is used as a fertilizer. Nitre-cake was used during the war in grease recovery, bleaching and dyeing, metal pickling, hydrochloric acid manufacture, mineral water making, as a flux, and other- wise to the total extent of 288,000 tons. (See Nitric Acid and Superphosphate of Lime.) Sodium Bromide (NaBr) and the Iodide (Nal), both of which are used in photography and medicine, are readily soluble in water and are white crystalline salts which are produced by processes like those used for preparing the corresponding potassium compounds. The fluoride (NaF) is a crystalline salt soluble in 25 parts of water, and the solution which attacks glass is used in etching and for other applications. It is prepared by neutralizing hydrofluoric acid with sodium carbonate. Sodium Nitrate (NaNO 3 ) is easily obtained in a state of purity by re-crystallization from its crude sources. It is a somewhat deliquescent and very soluble salt, 100 parts water dissolving nearly 69 parts at o C. and 102 parts at 40 C. Apart from its use in connection with the produc- tion of nitric acid it is of value as a fertilizing agent, a flux, in the glass industry, and for the production of potassium nitrate. (See Caliche and Potassium Nitrate.) Sodium Sulphites of which there are a number are referred to more particularly elsewhere. (See Sulphur.) They are used commercially on account of their value in SODIUM AND ITS COMPOUNDS 447 SODIUM (Continued) the brewing industry and as bleaching agents. The bisul- phate powder used in the brewing trade has a value in terms of SO 2 (sulphur dioxide) of from 60 to 62 per cent, and it is also prepared in liquid form of 70 Tw. strength yielding about 25 per cent. SO 2 in use. Sodium Hydrosulphite (Na 2 S 2 O 4 ) is a yellowish white crystalline substance, soluble in water, used as a bleach- ing and reducing agent. (See " Hydros.") Sodium Hyposulphite (Thiosulphite) (Na 2 S 2 O 3 5H 2 O), commonly known as " hypo," is largely used in photography as a "fixing agent" by reason of its value as a solvent of undecomposed silver salts. (See Sulphur Compounds.) Sodium Phosphates Of these, the chief compound is the common or di-sodium hydrogen orthophosphate, which is prepared commercially by interaction in solution between sodium carbonate and phosphoric acid. It is an efflorescent crystalline salt of composition Na 2 HPO 4 ,i2H 2 O, which becomes anhydrous upon heating, and is used in compound- ing baking-powder. Other crystalline phosphates are normal sodium orthophosphate (Na 3 PO 4 ), and sodium di- hydrogen orthophosphate (NaH 2 PO 4 ). The so-called microcosmic salt is a compound phosphate corresponding to NaH 2 PO 4 , in which an atom of hydrogen is replaced by ammonium (NaH(NH 4 )PO 4 ,4H 2 O) ; it crystallizes with 4 molecules of water. Sodium Pyrophosphate, an opaque, crystalline, white salt, has the composition Na 4 P 2 O 7 .6H 2 O, derived from pyro- phosphoric acid (H 2 P 2 O 7 ). There are a number of so- called metaphosphates obtained from metaphosphoric acid (HPO 3 ) (or so-called glacial phosphoric acid), including the sodium salt NaPO 3 ; the dimetaphosphate is Na 2 P 2 O 6 , and the trimetaphosphate Na 3 P 3 O 9 . Sodium Phosphites Of these, there are two salts, which are represented by the formulae Na 2 HPO 3 and NaH 2 PO 3 obtained from phosphorous acid (H 3 PO 3 ). Sodium Nitrite (NaNO 2 ) is a stable crystalline salt which is produced by reduction of the nitrate resulting from heating above the fusion-point, but is commercially made by an electrolytic process. It is used in the dye industry, and as a substitute for potassium nitrite. Sodium Sulphide (Na 2 S) is a soluble compound prepared for commercial purposes in crystalline form containing 448 SODIUM AND ITS COMPOUNDS SODIUM (Continued) 30 to 32 per cent, and in that of a liquid of 60 to 62 per cent, strength. It can be obtained by reduction of the sulphate by heating with carbon, or by the action of hydrogen sulphide upon caustic soda. It is used for deni- trating artificial silk, as a depilatory in tanning, etc. Sodium Oxalates The normal salt (Na^CaOJ and the acid salt (NaHC 2 O 4 H 2 O) are both crystalline and soluble in water, and are used in the textile industry. The normal salt occurs in a great number of plants, also in varech. The " salt of sorrel " of commerce is a mixture of the potassium acid salt KHC 2 O 4 and another salt KHC 2 O 4 + H 2 C 2 O 4 2H 2 O. Sodium Manganate and Permanganate See Manganese, p. 306. Sodium Tannate A compound of tannic acid (gallo- tannic acid) with soda. Sodium Borate See Boron, p. 65. Sodium Perborate (NaBO 3 4H 2 O) is a crystalline salt prepared by mixing a 3 per cent, solution of hydrogen dioxide with a saturated solution of borax in alkaline solution at a low temperature, when it is deposited in crystalline form on standing. It is a dangerous substance by reason of its tendency to decompose with violence. It contains 10 per cent, of oxygen, and is much used for washing and bleaching textile fabrics and as a general oxidizing agent. Sodium Acetate (NaC 2 H 3 O 2 ,3H 2 O) is a colourless, cry- stalline, efflorescent body soluble in water, and has many commercial applications. Sodium Arsenates are salts of which the following are well known viz., tri-sodium ortho-arsenate (or arseniate), Na 3 AsO 4 ,H 2 O ; di-sodium hydrogen ortho-arsenate, Na 2 H, AsO 4 ,i2H 2 O ; sodium di-hydrogen ortho-arsenate, NaH 2 , AsSO 4 ,H 2 O ; sodium pyro-arsenate, Na 4 As 2 O 7 ; and sodium meta-arsenate, NaAsO 3 . Sodium Chlorate (NaClO 3 ) and Perchlorate (NaClO 4 ) are white crystalline salts, soluble in water, prepared much in the same way as the more important potassium compounds and used for the same purposes. Sodium Bichromate (Na 2 Cr 2 O 7 ), a yellow, crystalline, soluble salt, used in the tanning and other industries, is prepared in a corresponding way to that by which the more important potassium bichromate is made. SODIUM SOILS 449 SODIUM (Continued) Sodium Aluminate (Na 8 Al 2 O 4 ) is a white compound soluble in water, and used as a mordant. Sodium Hypochlorite (NaCIO) See Chlorine, p. in. Sodium Amalgam (a white crystalline substance), ob- tained by dissolving sodium in from 2 to 10 per cent, of mercury at 200 C., is often used as a reducing agent. Sodium Benzoate (NaC 7 H 5 O a ) is a crystalline salt soluble in water, used as a food preservative, and in medicine. Sodium Citrate (2Na 3 ,C 6 H 5 O 7 ,iiH 2 O) is a white crys- talline salt, soluble in water, used in medicine and for compounding non-alcoholic drinks. Sodium Cyanide See Cyanogen. Sodium Formate (NaCHO 2 ) can be prepared in a crystal- line anhydrous state and also in association with water (NaCHO 2 ,H 2 O). Both are soluble in water. Sodium Ethoxide (NaC 2 H 5 O) Produced by the action of metallic sodium on absolute alcohol. Sodium Ferricyanide and Ferrocyanide resemble the corresponding potassium salts, and are used industrially for the same applications. (See Potassium, p. 393.) Sodium Glycerophosphate (Na2C 3 H 7 PO 6 H 2 O) A yellow viscid liquid, soluble in water and alcohol ; used in medicine. Sodium Phenate (or Carbolate) is a white, deliquescent, crystalline salt, soluble in water and alcohol, used as an antiseptic, etc. Sodium Silicate (Soluble, or Water-Glass) is made by calcining quartz with caustic soda or sodium carbonate and powdered coal, and subsequent extraction with water. It is known in the anhydrous form (Na 2 SiO 3 ), and also as Na 2 SiO 3 ,9H 2 O. It is soluble in water, and used in fire- proofing fabrics, making-up of paints, distempers, cements, etc., also for preserving eggs and many other applications. The silicate prepared as above described is probably an indefinite mixture and, according to some statements, silicon dioxide fused with sodium carbonate gives the soluble silicate Na 4 SiO 4 . Sodium Stannate See Tin. SOILS The outer crust of the earth, consisting mainly of various mineral matters resulting from the action of air and water upon rocks, mixed with organic (humous) substances derived from the decay of vegetable growths 29 450 SOILS SOLDER SOILS (Continued) and animal matter. The chemical constitution of soils (from which plants obtain their mineral food) varies according to the nature of the rocks from which they have resulted by weathering and they are roughly described as of sand, chalk, clay, or loam, etc., according to the prevailing features. It has been suggested that the soil possesses some of the attributes of colloids, such as powers of absorption and retention of water, and the soil moisture is certainly of great importance inasmuch as it constitutes the nutrient solution for growing vegetation. The plant residual pro- ducts present in soil, furnish the micro-organisms which abound in them with food, and of these, the two more important ones are cellulose and proteins which give rise respectively to humus and ammonia. The humus exercises important physical effects in the soil, and it is from the ammonia which becomes oxidized to form nitrates, that growing crops obtain their nitrogen food. One of these sporing organisms easily decomposes cellulose in contact with the air, and is named Spirochceta cytophaga, and gives a simple nitrogen compound such as a nitrate or ammonia ; it produces among other things a pigment like carotin. Other bacteria and fungi bring about the decomposition of protein. Two other soil organisms which flourish particularly in soil dressed with farmyard manure are Ps. ftuorescens and Ps. candatus. The changes effected by the many micro-organisms found in various soils are too varied to be dealt with in a work of this character, but some other details are given under the headings of Vegetation and Nitrification. (See also Plant Colouring Matters.) SOLANINE (C 62 H 93 NO 18 ) A poisonous constituent of potatoes contained to the extent of from 0-02 to o-i part per thousand, but present in the young shoots up to 50 parts per thousand. SOLAR AND STELLAR CHEMISTRY By means of the spectro- scope, it has been ascertained that sodium, magnesium, calcium, barium, copper, zinc, chromium, nickel, iron, hydrogen, etc., exist in the sun, and that many of the chemical substances known as constituents of the earth's composition go to the making of the stars. From a similar study of the nebulae, the conclusion has been drawn that they are masses of glowing gases. SOLDER See Alloys, Lead, and Tin. " SOLD IS SOL UTION 4 5 1 "SOLDIS" A disinfectant of phenolic and cresylic character, miscible with water. SOLS See Colloid. SOLUBILITIES See Chemical Combinations. SOLUBLE 1 Admitting of being dissolved or passing into solution ; for example, both sugar and salt are soluble in or dissolved by water. (See Solution.) SOLUBLE GLASS See Sodium Silicate (p. 449) and Silicon. SOLUTE See Solution. SOLUTION If a spoonful of salt be placed in a cup of water and stirred, the salt will gradually disappear ; in other words, the salt is dissolved by the water and constitutes the solute, whilst the water, which was previously tasteless, is the solvent, becomes saline in taste, and is called a solution of salt. When sugar is placed in a cup of hot water or tea or coffee, it dissolves, making the liquid sweet in character, and the mixture becomes in the same sense a solution of sugar. Many other liquids have this power of dissolving solid substances ; for instance, solid camphor is easily dissolved by spirits of wine (alcohol), and rosin can be dissolved in turpentine. Many liquids have the power of absorbing or dissolving certain gases; hydrochloric acid gas, ammonia, and chlorine are all soluble in water, absorption in this sense being the same thing as solution or solubility. Further, many liquids, such as some of the oils and hydrocarbons, are soluble in alcohol, ether, and some other liquids, and solution in this sense is also identical with that of a solid substance dissolved in a liquid. Gases also have the property of holding substances in solution ; air, for example, will take up a given quantity of water according to the temperature, and the mixture may be regarded as one of water dissolved in air. (See Air, p. 9.) There is good reason for believing that in some cases when substances are dissolved in liquids, real chemical combination takes place, as, for example, when sodium carbonate is dissolved in water; for if this solution be concentrated by evaporation to a sufficient extent, there is produced on cooling, a mass of crystals of common washing soda in which the sodium carbonate is definitely combined with water (Na 2 CO 3 ,ioH 2 O). There are certain conditions under which some solutions will solidify as a whole, and 452 SOLUTION SORREL (WOOD) SOLUTION (Continued) such solids were at one time regarded as cryohydrates, but this term is now restricted to solidified mixtures of solute and solvent (water), which are of the same composition as the solution, the " eutectic " point on a graph being that where the curves of temperature representing the separation intersect. As a general rule, the solubility of a solid in a liquid increases with the temperature, and when a solution will not dissolve any more of the solid substance at any particu- lar temperature it is said to be saturated,. A solution is said to be dilute in character when it con- tains but little of its particular ingredient, and is described as strong or concentrated when the proportion of dissolved substance is great in quantity. Many solutions which are not already saturated, can be strengthened or concentrated by evaporating off some of the solvent. For instance, a dilute solution of sodium nitrate (nitre) in water may be concentrated by the applica- tion of heat (which causes the evaporation or passing oft in the state of vapour of some of the water), to such a stage that when cooled, the excess of the salt will crystal- lize out on cooling. Similarly, a thin solution of rosin in turpentine can be concentrated by heating (which causes the evaporation or volatilization of some of the solvent turpentine) down to a thick, sticky mass. On the other hand, strong solutions can be weakened (diluted) by the addition of more solvent. (See Saturation.) SOLVENT See Solution, p. 451. SOLVENT NAPHTHA See Naphtha, p. 327, and Coal, p. 122. SOMBRERITE An impure mineral calcium phosphate (Ca 3 (PO 4 ) 2 ) found in Sombrero and other islands of the Antilles. SORBIC ACID (C 6 H 8 O 2 ) Found in the unripe sorb apple (Sorbus ancaparia) and mountain-ash berries. SOREL CEMENT A strong binding, made by mixing calcined magnesia with concentrated solution of magnesium chloride which sets to a hard mass of the composition MgCl 2 , 5MgO,#H 2 O (the value of x being about 17). SORGHO (Sorghum saccharatum) A sugar-producing grass resembling maize in appearance. SORREL (WOOD) (Oxalis acetosella) A plant which, in common with other oxalis and rumex, contains potassium oxalate. SOXHLET APPARATUSSPECIFIC CRA VlTY FLASK 453 SOXHLET APPARATUS is of glass and used for the extrac- tion of soluble parts of substances by the action of volatile solvents, such as fat from milk (absorbed in filter paper). SOYA-BEAN OIL Sp. gr., 0-936 to 0*970 ; melting-point, 22 to 3iC.; refractive index, 1-4760 to i'477 ; saponifi- cation value, 192 to 200; and iodine value, 137 to 141. A Chinese product expressed from soya-beans (Soja hispida and S. japonica), and used in soap-making, as a cattle food, also in the manufacture of margarine and as a substitute for linseed oil in varnish-making. Manchuria produced 2,000,000 tons in 1918. SPANISH FLIES See Cantharides. SPARTEIN SULPHATE A salt of spartein (C 15 H 26 N 2 ), a liquid alkaloid extracted from the tops of Spartium scoparium (broom) and used in medicine. SPATHIC IRON-ORE A mineral ferrous carbonate (FeCO 3 ). SPATULA A flat blade used for transferring solid or pasty substances from one container to another. Spatulas are made of various materials, according to the nature of the substance to be manipulated some of steel fixed in a wooden handle; others of ivory, platinum, nickel, alu- minium, etc. SPEARMINT OIL An essential oil containing carvone dis- tilled from the fresh American herb Mentha viridis (ordinary garden mint) and the German Mentha crispa. It has a sp. gr. of 0-92 to 0-94, rotation 36 to -48, and is used in medicine, for flavouring, and in confectionery. SPECIFIC GRAVITIES The relative weights of equal volumes of gases compared with hydrogen as unit, are known as their specific gravities or vapour densities. The specific gravities of liquids and solids are their relative weights as compared with the density of water as the unit. (See Hydrometer and Vapour Densities.) SPECIFIC GRAVITY FLASK This is used for determining the specific gravity of fluids by weight, and in practice it is usual to employ a stoppered flask filled at 15 -5 C., the stopper being inserted so that the liquid overflows and no air is left in the flask. Its weight (after drying it externally) as compared with that of water determines the specific gravity. The weight of the liquid (after deducting that of the empty dry flask) having been ascertained, and that of the same quantity of water at the same temperature being known, the specific gravity of the liquid is ascertained by dividing it by the latter. (See also Hydrometer.) 454 SPECIFIC HEATS SPECIFIC HEATS It is a known fact that equal weights of different substances absorb different quantities of heat through the same range of temperature water, for example (which exhibits the highest thermal capacity of all known substances), requires thirty times the amount required by the same quantity of mercury to raise it through a given number of degrees. These relative capacities furnish the so-called specific heats of substances, which may be defined as the ratios of their thermal capacities to that of an equal weight of water ; thus, the specific heat of water being taken Element. Specific Heat. Atomic Weight taken as Atomic Heat. Antimony 0-0495 I2O"2 5'95 Arsenic 0*083 74-96 6-22 Bismuth 0*0305 208 6-34 Cobalt 0*10303 58-97 6-08 Copper 0*09232 63-57 5*1 Gold 0-03035 197-2 5-99 Iron 0-10983 55^4 6-36 Lead Lithium 0-0315 0-94 207-2 6-94 6-52 6-52 Manganese ... O-I2I 54'93 6-70 Mercury 0-0334 200*6 6-70 Nickel 0*10842 58'68 6-16 Platinum 0-03147 195-2 6*14 Potassium 0-166 39* I 6-51 Silver 0-0559 107-88 6*03 Sodium 0-29 23 670 Tin 0*0559 118-7 6-65 Zinc 0-0939 6"5'37 6-14 j as the unit, that of mercury is ^ th or 0-033. There is a definite relation between the specific heats and the atomic weights of various solid elements, the former being inversely proportional to the numbers known as their atomic weights. This law, known as that of Dulong and Petit, is expressed by stating that the thermal capacities of atoms of the elements in the solid state are equal, and the table given above briefly illustrates this relationship. The molecular heat of a compound is the sum of the atomic heats of its constituent elements. SPECTROSCOPE 455 SPECTROSCOPE An instrument by means of which the light emitted by strongly heated substances can be examined, as described herein. It is constructed of one or more prisms by which the coloured rays are separated when light is made to pass through them. This analysis or splitting up of light into the different colours of which it is constituted, furnishes what is termed the prismatic spectrum ; each colour having its own peculiar refrangibility ranging from the red rays which are the least refrangible, to the deep violet which are most refrangible, at the other end of the rainbow. Various chemical salts when heated in the blow-pipe or nearly colourless Bunsen-burner flame, impart a peculiar colour which is indicative of their nature, but where mixtures are concerned, the indication is lost on account of the merging or blending of the various colours which takes place. Sodium compounds give a yellow colour to flame; potassium salts tinge the flame purple; whilst lithium salts communicate a crimson-red colour. The colour given by the salts of rubidium and caesium is in- distinguishable by the naked eye from that of potassium compounds, but when these coloured flames are examined through the telescope (forming a part of the instru- ment under description) the spectrum affords an easy and assured method of diagnosis, inasmuch as the chemical salts under examination furnish their distinct bright bands of light. Sodium compounds give a distinct line or group of lines in the yellow, lithium gives one band in the red and another in the yellow, and potassium also gives two bands, one in the deep red and another in the violet, and when mixtures are examined, the individual or distinctive bands are all respectively revealed. This method of detection is so delicate that so small a part as T 8Qoooooo th of a grain of sodium salt and ^oi o00 th of a grain of lithium can be detected. Characteristic spectra are afforded not only by sub- stances which give colour to flame but by every elementary body when heated to the degree at which its vapour becomes luminous. Many of the elements were discovered by the use of spectrum analysis, including caesium, rubidium, thallium, indium, helium, and gallium, and before anything was known of their unique chemical properties. The instrument consists in its simplest form of a prism (A) fixed upon a stand placed in line with a hollow tube (B) provided with a slit or shutter (C) at the end 456 SPECTROSCOPE SPECTROSCOPE (Continued) opposite to which the flame is placed for examination. The rays of light passing along this tube through the slit are received upon the prism through D a lens fixed in the tube called the collimator which renders the rays parallel, and the refracted rays are received by the observer using the telescope (D) (see Figure), which is placed in such posi- tion that the bent rays fall upon its lens, and are magnified by it. The illustration is that of one of Browning's spectroscopes. Emission spectra can be produced in a number of ways viz., by the use of flame such as that of a Bunsen lamp in respect of the more or less volatile metallic salts ; or by the electric arc, which furnishes a much higher temperature, the spectrum being obtained by placing the substance to be examined into the arc between the carbon poles ; or by means of the sparks from an induction coil made to pass between small poles of the substance, or discharged through fases a method which can also be applied to solutions ; or, nally, by the use of cathode streams for the production of phosphorescence in solid substances. ' The relation between the powers of emission and those of absorption for rays of the same wave-lengths is constant for all bodies at the same temperature. Organic solutions were first examined by photographing the spark spectrum of an alloy of tin, lead, cadmium, and bismuth, as obtained through a solution of the subject under examination. The bright yellow sodium lines are made to appear as dark lines or spaces, by allowing the rays of a white light like that of the oxyhydrogen flame or an incandescent platinum wire to pass through a flame coloured by a sodium compound, and then to fall upon the slit of a spectroscope, because the yellow flame absorbs the same kind of light as it emits, and so each substance in the vaporous state has the power of absorbing the same rays as it emits, or being opaque to same. This accounts for SPECTROSCOPE SPIRITS OF WINE 457 SPECTROSCOPE (Continued) the dark spaces or so-called Fraunhofer lines observed in the solar atmosphere, these being, as is believed, bright lines reversed, and indicative, therefore, of the presence in the sun's atmosphere of those substances which are capable of yielding the coincident bright lines, including iron, sodium, calcium, magnesium, chromium, barium, copper, zinc, hydrogen, and nickel. By the investigation of emission and absorption spectra, using a variety of appliances adapted to the many different substances requiring examination, it has been found possible not only to acquire a very definite knowledge of the constitu- tion of the sun's atmosphere, the fixed stars, and the so-called nebulas, but these methods have been turned to account for the identification of precious stones, dyes, and colouring matters; the detection of alum in wines and fruit juices, blighted wheat in flour, and bloodstains ; the estimation of alkaloids, the valuation of indigo samples, the examination of essential oils, sugar analysis, etc. The spectroscope has also proved of great value in the investigation of many organic compounds, radical groups such as CH 2 , CH 3 , NH 2 , C 6 H 6 , HO, etc., all giving characteristic absorption bands. SPECTRUM The band of colours into which white light can be broken up, as, for example, when passed through a prism. (See Light and Spectroscope.) SPECULAR IRON-ORE Ferric oxide (Fe 2 O 3 ). SPEISS-COBALT See Cobalt. SPELTER A commercial name for zinc. SPERM OIL See Fish Oils. SPERMACETI See Waxes. SPERRYLITE A very rare mineral containing platinum com- bined with arsenic (PtAs 2 ). SPHAGNUM A club moss (Sph. acutifolium) which grows abundantly on peat moors, and which has proved of great utility as a soft, absorbent, surgical dressing mildly anti- septic in character. SPIKE OIL See Lavender (Spike) Oil. SPINELLE A natural crystalline magnesium aluminate (MgO,Al 2 O 3 ), used as a gem and as an abrasive. SPIRITS OF WINE Alcohol of indefinite strength. (See Alcohol.) 458 SPODUMENE-STARCH SPODUMENE See Lithium. " SPONDITE "A substitute for glass, being an application of cellulose acetate dope to wire netting. SPONGES are living organisms of various species (found adherent to rocks in the Mediterranean and elsewhere), the tissues of which, constitutionally, are, from a chemical point of view, nearly related to the fibroin of silk. SPONGY PLATINUM^See Platinum and Catalytic. SPONTANEOUS COMBUSTION ensues as a result of the develop- ment of heat arising from chemical changes ; thus, cotton waste soaked in linseed oil will sometimes fire in consequence of the rapid oxidation of the oil. Similarly phosphorus ex- posed to the air will take fire, and burnt lime during slaking with water develops enough heat to fire wood that may happen to be in contiguity. SPBUCE OIL Distilled from the leaves and twigs of Picea alba and P. nigra, containing pinene, cadinene, and bornyl acetate. It is colourless, of pleasant odour, with sp. gr. about 0-9, optical rotation -22 to -25; soluble in al- cohol and ether, and used in medicine and perfumery. STALACTITES Deposits of calcium carbonate like icicles, formed from dripping water in the roofs of calcareous caves, due to the escape of carbon dioxide from a solution of calcium carbonate dissolved in water and previously held in solution by its agency. STALAGMITES Similar deposits growing upon the floor of caves out of the water dropped from above. STANDARD SOLUTIONS See Normal Standard Solutions and Reagents. STANNATES See Tin. STAR-ANISE OIL A colourless, volatile oil from the seeds of Ilicium anisatum (China and Japan) containing anethol and used for flavouring, etc. STARCH (Amylum) is found present in some of the parts of nearly all plants, in the form of organized or structural granules of varying size, and abundantly in wheat, maize, barley, oats, arrowroot, rice, and the potato. Chemically it is a carbohydrate (C S H 10 O 6 ), this formula representing the proportions of the constituent elements, the number in the molecule being unknown. Potatoes contain on an average, about 20 to 27 per cent, of starch ; wheat from 50 to 75 per cent. Sago is a starch produced from the sago- palm ; tapioca is made from the Jatropha manihot ; arrowroot is the STARCH STEARIC ACID 459 STARCH (Continued) starch of the tropical plant Mavanta arundinacea ; and arum is a starch similar to sago obtained from the root of A yum maculatum. Lichenin otherwise known as moss starch is contained in many lichens, including Iceland moss ; inulin is another variety, present in dahlia and other roots ; whilst glycogen is a form of animal starch found in the livers of mammalia. In plant life, starch is converted into sugar during the transference of the sap. Starch is not soluble in cold water, but when heated with water it swells up and assumes a more or less pasty con- dition, forming a kind of emulsion, commonly known in chemical laboratories as "starch solution," although but little passes into real solution. Both in its soluble and insoluble conditions starch com- bines with iodine, forming a deep blue compound. If starch be heated in the dry state for some hours at a temperature of 200 C., its character becomes changed, and the product is quite soluble in water, being what is known commercially as dextrine or British gum, as used by calico- printers for mixing with their colours, also as an adhesive, for sizing, and other purposes. By the action of dilute acids and ferments, starch yields a number of sugar-like bodies known as dextrose, maltose, etc., which are largely employed in brewing and other industries, being substances which, like ordinary sugar, admit of being fermented into al- cohol. (See Carbohydrates. ) By a special process of fermen- tation, acetone is now commercially prepared from starch. Starch is used in laundries and the finishing of textiles ; also in the manufacture of adhesives, invalids' foods, dextrine, and as a face-powder, etc. STASSFURT SALTS The dried-up residue of a great pre- historic ocean, consisting largely of potassium salts. (See Potassium.) STEARIC ACID (C 18 H 36 O 2 ) (sp. gr. 0-8428) A solid fatty acid found present in most animal and vegetable fats and oils, and generally associated in varying proportions with palmitic and oleic acids ; all in combination with glycerine in the form of glycerides or glyceryl esters. It is most abundant in the more sojid fats and forms hard soap when saponified, setting free the glycerine as explained elsewhere. (See Soaps.) It can be readily prepared from beef or mutton fat and when pure is white, crystalline, and melts at 68 C. It is largely used in making candles. (See Fats.) 460 STEA R1N STRONTIUM STEARIN ((C 18 H 35 O 2 ) 3 C 3 H 5 ) The glyceride or glyceryl ester of stearic acid, occurring as a solid constituent of fats and yielding potassium stearate (soap) and glycerine (glycerol) upon saponification with alcoholic potash. It melts at 71 C., has a sp. gr. 0-862, and is soluble in ether, chloro- form, and carbon disulphide. (See Fats.) STEATITE A form of talc, slabs of which are often used for making firestones in furnaces and stoves. STEEL See Iron, p. 270. STELLITE A hard alloy of cobalt, chromium, and tungsten melted together in an electric furnace at over 1,500 C. used for high-speed cutting tools, for making cutlery and surgical implements, and for use as a nitric acid resistant material. STEPHANITE (5AgS.Sb 2 S 3 ) A native sulphantimonite of silver. STEREO-ISOMERISM See Isomerism. STIBILITE Native oxide of antimony. STIBNITE (Grey Antimony) Native sulphide of antimony (Sb 2 S 3 ). STICK LAC Shellac. STILBITE A mineral, crystalline hydrated silicate of calcium and aluminium. STILL See Retort. STOCKHOLM TAR A tar distilled from the resinous wood ot the pine, and largely used in connection with wooden shipbuilding for caulking. It is soluble in turpentine. STORAX (Styrax) See Balsams and Styrene. STROMEYERITE A mineral double sulphide of silver and copper (Ag 2 S,Cu 2 S) found in Arizona and elsewhere. STRONTIANITE Native carbonate of strontium (SrCO 3 ). STRONTIUM (Sr) Atomic weight, 87-6; sp. gr., 2-54; melt- ing-point, 900 C. Strontium is contained in the mineral known as strontianite in the form of carbonate (SrCO 3 j, in brewsterite as silicate, and in celestine as sulphate (SrSO 4 ). The metal is soft and of a pale yellow colour, and has to be kept in naphtha, as it readily oxidizes in the air and possesses the property of decomposing water. It is pre- pared by the electrolysis of the fused chloride. Like magnesium, it burns brilliantly upon ignition in the air, producing the monoxide SrO. STRONTIUM STY RONE 461 STRONTIUM (Continued) Strontium Monoxide (strontia), like lime, combines with water, with evolution of heat, forming the hydroxide (Sr(HO) 2 ) which is strongly alkaline and more soluble in water than calcium hydroxide. It is used on a large scale in the purification of sugar, with which it forms a combina- tion (saccharate of strontia) which can be decomposed by carbon dioxide. (See Saccharate, Strontium and Sugar.) There is a dioxide (SrO 2 ) which upon heating to redness, parts with oxygen and is reduced to the monoxide. It is obtained in pearly crystals having the composition SrO 2 ,8H 2 O by adding hydrogen peroxide to a solution of the hydroxide, and is used to some extent in bleaching. Strontium Chloride (SrCl 2 6H 2 O) is a white, crystalline salt, soluble in water and alcohol and used in the pro- duction of red flames. Strontium Nitrate (Sr(NO 3 ) 2 ), obtained by dissolving the oxide or carbonate in dilute nitric acid, is a white crystalline salt extensively used in the production of red fireworks. It crystallizes with water as Sr(NO ? ) 2 4H 2 O, and when heated with combustible matter, the mixture takes fire and burns with a characteristic crimson colour. Strontium Carbonate is a white substance, practically in- soluble in water, used in pyrotechnics and the manufacture of iridescent glass. Strontium Sulphate (SrSO 4 ) is white and practically insoluble in water. Strontium Saccharate See Saccharate, Strontium. STRYCHNINE (C 21 H 22 N 2 O 2 ) An exceedingly poisonous white, crystalline alkaloidal base extracted from Strychnos nux vomica and St. Ignatius' beans, etc. It melts at 268 C., is soluble in chloroform and used in medicine. STUCCO A coloured form of plaster of Paris prepared with a solution of size. STYRENE (Styrol) (C 6 H 5 CH.CH 2 ) A refractive, oily, yellow- ish liquid of aromatic odour, with a sp. gr. of 0-912 and boiling-point 146 C. ; soluble in alcohol and ether, obtained from liquid storax (sty rax), and used in medicine. It polymerizes spontaneously upon standing, into a jelly-like mass. (See also Cinnamic Alcohol.) STYRONE See Cinnamic alcohol. 462 SUBERIC ACID SUGAR SUBERIC ACID (C 8 H 14 O 4 ) A member of the oxalic series of acids, originally obtained by the action of nitric acid upon cork, but easily prepared, similarly, from oleic acid or other fatty acids. It is a crystalline body which melts at 140 C., dissolves readily in boiling water, and mixes with fixed oils. When strongly heated, it gives off suffocating vapours. SUBLIMATE A solid deposit resulting from the condensation of a vapour. SUBLIMATION A sort of dry distillation or volatilization of solid substances like camphor, iodine, naphthalene, and sulphur, and the condensation of their vapours anew into solid form. SUBSTITUTION PRODUCTS are those which result from the substitution of one element or radical by another in any chemical substance. For example, methane (CH 4 ) yields four substitution products with chlorine, by replacement of respectively i, 2, 3, and 4 atoms of hydrogen, represented by CH 3 C1, CH 2 C1 2 , CHC1 3 , and CC1 4 . Again, nitro- benzene (C 6 H 5 NO 2 ) is a substitution product obtained from benzene (C 6 H 6 ) by the replacement of i atom of hydrogen by the group NO 2 . SUBSTRATE See Enzymes, p. 178. SUCCINAMIDE (C 4 H 8 N 2 O 2 ) The amide derivative of -succinic acid, produced by the interaction of ammonia and ethyl succinate. SUCCINIC ACID (C 4 H 6 O 4 ) is found amongst the products of the distillation of amber and in certain animal juices and resins. It can be prepared in several ways, including the oxidation of butyric acid and the hydrolysis of ethylene dicyanide. It forms large colourless crystals, is soluble in water, fuses at 186 C., and boils at 235 C., when its vapour is dissociated into succinic anhydride (C 4 H 4 O 3 ) and water. Its alkaline salts are soluble in water. SUCCINIMIDE (C 4 H 5 NO 2 ) The imide derivative of succinic acid ; a crystalline substance produced by heating hydrogen- ammonium succinate. SUCRASE Invertase. SUCROSE Cane Sugar. SUET See Fats. SUGAR (Cane Sugar, Beet Sugar, Saccharose, Sucrose) (C^H^OyJ A hard, white, crystalline, sweet substance, occurring in the stems or juices of certain grasses and many plants, including the red-beet and sugar-maple, and par- ticularly in the sugar-cane, from which it is produced by SUGAR SUGAR OF MILK 463 SUGAR (Continued) pressure between rollers and subsequent purification. The sugar juice, as expressed from the canes, is first of all defecated that is, treated with milk of lime to neutralize acidic ingredients, and boiled to coagulate the albuminous matters contained in the juice, after which the excess of lime is carbonated by the passage of carbon dioxide. The settled or filtered liquor resulting from this preliminary treatment is evaporated in vacuo, and yields upon cooling a mixture of sugar crystals and syrup, the former being separated from the treacle by centrifugalization. It is refined by dissolving in water and decolourization by perco- lation through a filter of animal charcoal, after which it is again concentrated and crystallized. The molasses or treacle containing some crystalline sugar still in solution is treated with a solution of strontium hydroxide, which forms an insoluble combination with it, and after removal by filtration, is decomposed by the action of carbon dioxide upon it as suspended in water, thus forming insoluble strontium carbonate, the sugar meanwhile passing into solution, from which it is recovered by concentration and crystallization. The molasses finally left is used for making rum, or ordinary alcohol, and the "begasse," or crushed sugar-cane mass is used as fuel. In course of the evaporation of maple sap to the syrup stage, a precipitate called " sand," and containing from 60 to 80 per cent, of calcium malate, is deposited, and finds use in the preparation of baking-powders, etc. Sugar is also manufactured from beetroots, and is marketed in many forms, such as loaf, cube, lump, granular, icing, etc. The so-called soft sugars contain a proportion of molasses, also of invert sugar. Sugar melts at 160 C., into what is known as barley- sugar, and when further heated forms "caramel." Sub- jected to the action of acids, cane sugar is " inverted " by hydrolysis, and whereas it was originally dextro-rotatory, the invert sugar which is formed is laevo-rotatory and consists of a mixture of fructose and glucose, (See also Carbohydrates, Saccharoses, and Glucose.) Sugar in its several forms is a valuable food, and is largely used as a sweetener, in the preparation of syrups, preserves, and jams, and for the manufacture of alcohol, etc. SUGAR-CANE WAX See Waxes. SUGAR OF LEAD See Lead. SUGAR OF MILK See Lactose. 464 SUINT-SULPHUR SUINT A peculiar fatty body found present in sheep's wool, containing also a quantity of potash. A fleece weighing 9 pounds contains about 20 ounces of suint, of which about one-third is potash. The fat is used for soap making and in the preparation of lanoline. (See also Degras and Wool- wax.) SULPHATES-See Sulphur. SULPHIDES See Chemical Compounds and Sulphur Com- pounds. SULPHIDES (Organic) The substances known as mercaptans are in the nature of sulphides ; ordinary mercaptan is ethyl hydrosulphide (C 2 H 5 HS) and ethyl sulphide is (C 2 H 5 ) 2 S. (See Mercaptans.) SULPHITES See Sulphur. SULPHOCARBOLATES are compounds prepared from phenol- sulphonic acid (C 6 H 5 SO 3 H). The zinc salt is used medicinally. SULPHOCYANIC ACID, otherwise known as thiocyanic acid (CNSH), is the sulphur analogue of cyanic acid (CNOH). SULPHOC YANIDES (Sulphocyanates) are combinations of bases with sulphocyanic acid. By fusion of sulphur with potas- sium cyanide or sodium cyanide the corresponding potas- sium sulphocyanide (KCNS) and sodium sulphocyanide (NaCNS) are formed. They are readily soluble in water and are not poisonous. Sulphocyanides can be prepared from the ammoniacal liquor of gasworks. SULPHONAL (Sulphone Methane) (C 7 H 16 S 2 O 4 or (CH 3 ) 2 : C(SO 2 .C 2 H 5 ) 2 ) A colourless crystalline substance, used as a soporific and hypnotic. It melts at 125 C. and is soluble in alcohol. SULPHONATION The treatment of organic bodies with sul- phuric acid whereby sulphonic acids are produced, the products containing the group SO 2 ,OH. Thus benzene (C 6 H 6 ), treated with fuming sulphuric acid, yields benzene sulphonic acid (C 6 H 5 ,SO 2 ,OH) : C 6 H 6 + H 2 S0 4 = C 6 H 6 SO 3 + H 2 O. SULPHUR (S) Atomic weight, 32. Large quantities of sulphur are found naturally in Japan, Spain, and the United States of America, also in volcanic districts, including Italy, Sicily, and Iceland, and there are considerable beds of it in the Locken mines south-east of Trondhjem (in Scandinavia), SULPHUR 465 SULPHUR (Continued) Transylvania, China, India, and California. The Sicilian production of sulphur in 1919 was 181,374 tons. Sulphur is also found naturally in various forms as sulphides, of which the best known are galena, or lead sulphide (PbS), zinc blende, or zinc sulphide (ZnS), iron pyrites, or iron sulphide (FeS 2 ), and copper pyrites (Cu 2 Fe 2 S 4 ). (See Pyrites.) Cinnabar is a natural mercury sulphide (HgS). The mineral gypsum, or calcium sulphate, contains sulphur in combination with calcium and oxygen and water (CaSO 4 .2H 2 O) ; whilst heavy spar also contains sulphur in the form of barium sulphate (BaSO 4 ). Sulphur is obtained from its crude natural form by melting and vaporization, by which means it is sublimed and thus purified. As a constituent of pyrites, it is utilized in the manufacture of sulphuric acid described elsewhere (p. 468), and it can be made from the sulphurized oxide of iron resulting from the process used in gasworks for free- ing the gas from hydrogen sulphide. This is done either by burning off the sulphur into the form of sulphur dioxide or oxidation of the sulphurized mass, thereby revivifying the ferric oxide : 2FeS + 3O + 3H 2 = 2 Fe(OH) 3 + 28, the sulphur thus set free being subsequently distilled or burnt off. The total amount of sulphur obtained in a pure state annually, is about 800,000 tons, and about one half of this comes from Sicily and the U.S.A. A German war-time process for preparing sulphur was based upon the reaction that takes place between calcium sulphide and magnesium chloride when boiled together, the hydrogen sulphide (H 2 S) thus liberated being burned in the air under such conditions that only the hydrogen is burned and the sulphur is deposited. When H 2 S and SO 2 are mixed together, all the sulphur is deposited according to the equation H 2 S + SO 2 = 2H 2 O + 28. The calcium sulphide primarily employed and converted into sulphate is reconverted into sulphide by heating it together with coal in a revolving furnace at 1,100 C. Sulphur affords one of the most interesting examples of substances which can assume a number of varying or so-called allotropic forms. In its ordinary form, it is a 30 4 66 SULPHUR SULPHUR (Continued) yellow crystalline body of octahedral formation, but by melting it under certain conditions it can be obtained in the form of prismatic needles of transparent character which melt at 119 C. and upon exposure to the air, gradu- ally lose their transparency, crumble up, and assume once more the form of octahedra. The influence of heat upon sulphur is remarkable. The ordinary rhombic form melts at about 112-8 C. to a yellow, limpid (thinnish) liquid ; but if the temperature be allowed to rise to 230 C., it becomes quite viscid (thick) and darkens very much in colour. If the heat be still further raised, it again becomes more fluid, but not so fluid as when first melted. If, when in the viscous state, it be allowed to cool suddenly (as by pouring it into cold water), it solidifies into a soft mass which can be drawn out into elastic threads having a sp. gr. of 1-96, whereas the natural crystals of sulphur have a sp. gr. of 2-07. This form can be again transformed into the original by heating it to 1 00 C., when it suddenly returns to the brittle con- dition with an evolution of heat. This change also takes place if it is kept for a short time. When sulphur is distilled in small quantities and the vapour allowed to condense in a vessel not artificially cooled, it takes the form of red oily drops which remain fluid for some hours, but afterwards pass into the solid condition. These changes appear to be due to varied molecular arrangements corresponding to environment. Between 117 and 157 C. the sulphur molecule appears to be S 6 and between 180 and 445 C. S 18 . It may be sublimed that is to say, it can be volatilized or made to assume the form of vapour, which can then be condensed into the solid state. Sulphur is soluble in carbon disulphide (CS 2 ), and can be obtained in crystalline form therefrom. It is marketed in the forms of crystals, " roll," " precipitated," and " sub- limed." At one time, sulphur was largely used in the making of matches, but this has been superseded by other methods. It is used in the manufacture of gunpowder and sulphuric acid, also in vulcanizing processes, in pharmacy in com- pounding so-called milk of sulphur and other medicaments, and for fumigating beer casks and infected rooms. Sulphur burns in the air with a blue flame and gives rise to the production of sulphur dioxide (SO 2 ), a gas of pungent, SULPHUR AND ITS COMPOUNDS 467 SULPHUR (Continued) irritating nature which may be condensed and liquefied, or a solution of it in water can be prepared. In all three forms it is used for disinfecting purposes ; also for bleach- ing straw, silk, wool, and sponge. Kingzett's Sulphur Candles, for fumigating purposes, are so constructed that the burning of the sulphur is com- pletely ensured, and meanwhile causes the simultaneous evaporation of water, which materially assists the steri- lizing effects of the generated sulphur dioxide. Sulphur is said to exercise a valuable toxic action as a fungicide ; for example, flowers of sulphur applied in paste form to hot- water pipes in greenhouses will keep in check, diseases of the mildew type on plants kept in the houses. Sulphur Oxides Of the oxides of sulphur, the two most important are the gaseous dioxide (SO 2 ) (which is soluble in water to the extent of 79*789 volumes in i volume at o C.), and the trioxide (SO 3 ), the latter being produced when a mixture of SO 2 and oxygen are passed over strongly heated spongy platinum (which acts as a catalytic agent and effects their combination) in the form of white silky needles when condensed in a cooled receiver. It is a volatile body which fumes in the air, melts" at 14-8 C., and combines eagerly with water, forming sulphuric acid = H a SO 4 . The acids formed from the oxides include hyposulphur- ous, sulphurous, sulphuric, and thiosulphuric acids. Other combinations are known as dithionic acid (H 2 S 2 O 6 ), tri- thionic acid (H 2 S 3 O 6 ), tetrathionic acid (H 2 S 4 O 6 ), and pentathionic acid (H 2 S 5 O 6 ). Hyposulphurous (Hydrosulphurous) Acid (H 2 S 2 O 4 ) can be made from sulphurous acid by reduction with zinc, when the hydrogen generated in a nascent state is not evolved, but combines as expressed in the equation 2H 2 S0 3 +H 2 =H 2 S 2 4 + 2H 2 0. In solution, this unstable acid exhibits a yellowish colour and considerable bleaching properties. Sulphurous Acid (H 2 SO 3 ) is known only in solution and is somewhat unstable, but less so than the hyposulphurous acid. It has a strong odour of sulphur dioxide, and gradually undergoes decomposition by absorption of at- mospheric oxygen. Being dibasic in character, it forms two series of salts, which are represented by potassium 468 SULPHUR AND ITS COMPOUNDS SULPHUR (Continued) hydrogen sulphite, or acid potassium sulphite (KHSO 3 ), and potassium sulphite (K 2 SO 3 ). The various sulphites are crystalline compounds and 'are obtained by the interaction of sulphur dioxide and an alkali in the presence of water, a hot aqueous solution of the alkali carbonate being treated with the SO 2 gas until the desired salt is completely formed in solution of the requisite strength, to crystallize out on cooling. The calcium salts are similarly made, using calcium hydroxide (Ca(OH) 2 ) or the carbonate (CaCO 3 ). Thiosulphuric Acid (H 2 S 2 O 3 ) is not known in the free state, being of very unstable character, but it forms well- defined salts, obtained by digesting flowers of sulphur in solutions of sulphites. Of these the sodium compound, (Na 2 S 2 O 3 ,5H 2 O), incorrectly known as sodium hyposulphite (which can be prepared by the action of sulphur dioxide on sodium sulphide in solution, and should be termed sodium thiosulphate), is the most important. It is a crystalline body very soluble in water, and largely used in photography in the process known as "fixing " ; also as an " antichlor." Sulphuric Acid (H 2 SO 4 ), or ordinary oil of vitriol, is one of the most important sulphur compounds and is manu- factured from sulphur dioxide as produced by the roasting of pyrites, or by burning sulphur in the air by oxidation of the sulphur dioxide (SO 2 ) vapour in contact with moisture (water vapour) by the agency of gaseous nitric peroxide, thus : 2S0 2 + 2NO 2 + 2H 2 = 2H 2 SO 4 + 2ND, the sulphuric acid thus produced being absorbed or dis- solved in water. In other words, through the agency of the nitric peroxide the SO 2 is made to take up an extra atom of oxygen, and this, in combination with water, furnishes sulphuric acid The nitric peroxide is obtained from nitric acid, which in turn is produced by the action of strong sulphuric acid (H 2 SO 4 ) upon sodium nitrate (NaNO 3 ), thus : 2NaNO 3 + H 2 S0 4 = Na 2 SO 4 + 2 HNO 3 . In this process, the nitric peroxide (NO ? ) gives up some of its oxygen, being reduced to nitric oxide (NO), which becomes peroxidized again by the air, regenerating the NO 2 , to serve anew the same purpose. (See Alkali Trade.) In the practical manufacture of sulphuric acid, the SULPHUR AND ITS COMPOUNDS 469 SULPHUR (Continued) gaseous sulphur dioxide mixed with air is " nitrated " by passing the mixture up what is known as a " Glover tower," in which it encounters a stream of nitric acid or nitrated sulphuric acid slowly flowing over flints, after which it is passed into the leaden condensing chambers into which steam or water (in the form of fine spray) enters, and in which the sulphuric acid is condensed. The current of air carrying nitrous gases is then made to pass up what is known as the "Gay Lussac tower," where it encounters a stream of sulphuric acid trickling over coke packed in the tower, with the result that the nitrous gases are absorbed, and the acid so charged is used over again in the " Glover tower." The acid prepared in this way, is of about 70 per cent, strength and is concentrated by evaporation or by passage down a tower in the form of fine spray, in which it encounters a current of hot producer gas which carries off the water, the concentrated acid being collected at the base. (See also Cottrell Precipitating Plant.) Oxidation of ammonia as a means of supplying the oxides of nitrogen required for the chemical reactions in the chamber process of sulphuric acid, has come into use in recent years. (See Nitrogen Fixation.) Fuming Sulphuric Acid (" Oleum ") is really a solution of sulphur trioxide (generally about 10 per cent.) in 100 per cent. H 2 SO 4 and is now made on a rapidly increasing scale by the catalytic or contact process, as referred to already under Sulphur Oxides. Instead of using a mixture of sulphur dioxide and oxygen, ordinary sulphuric acid can be employed. This is split up by great heat into water, sulphur dioxide, and oxygen ; the water is removed and the remaining fixed gases are passed over ferric oxide (which effects the combination to the extent of about 60 per cent.), and then over pumice-stone coated with finely divided platinum, maintained at a temperature lower than that used to break up the original acid, to complete the combination into the tri-oxide (SO 3 ), which can then be condensed as such or in sulphuric acid (as made by the ordinary process) in order to concentrate it. The platinum is deposited on the pumice-stone by soaking it in a solution of platinum and ammonium chlorides and heating to dull redness. (See Nordhausen Acid.) In the pure state, sulphuric acid is a heavy, colourless, oily body of very corrosive properties, having a great affinity for water, and behaving with the oxides and 470 SULPHUR AND ITS COMPOUNDS SULPHUR (Continued} carbonates much in the same way as hydrochloric and nitric acid, forming the corresponding sulphates. The annual production of the various forms of this acid in the United Kingdom exceeds 4 million tons, and it finds employment in a great number of industrial applications, such as the manufacture of explosives, dyes, washing soda, glucose, ammonium sulphate, superphosphate of lime, etc. Sulphates Sulphuric acid forms several definite com- binations with water represented by the formulae H 2 SO 4 , H 2 O, and H 2 SO 4 ,2H 2 O, so that in addition to the ordinary sulphates corresponding to H 2 SO 4 , such as the potassium salt (K 2 SO 4 ), the barium salt (BaSO 4 ) and potassium hydrogen sulphate (KHSO 4 ), there are known compounds corresponding to the other two molecular combinations. Hydrogen Sulphide or Sulphuretted Hydrogen (H 2 S) is an offensive smelling gas which is found in nature in volcanic areas and is contained in many mineral waters, (such as Harrogate), which are used medicinally. It can be prepared by the action of dilute hydrochloric acid (or sulphuric acid) upon ferrous sulphide (see p. 219) and is colourless, poisonous, soluble in water (to the extent of 4-37 volumes in i volume water at o C.), and burns when ignited, producing sulphur dioxide and water It forms sulphides by its action on many metals, oxides, and metallic salts, and tarnishes many metals by direct combination. The sulphides of the metals of the alkalies and alkaline earth groups are more or less soluble in water, but the others are insoluble. There is a process in use for the recovery of the sulphur in alkali waste (based upon the production of hydrogen sulphide) by its treatment when mixed into a paste with water, in several successive vessels with carbon dioxide or lime-kiln gas (which largely consists of that body). The carbon dioxide at first decomposes the calcium sulphide of the waste, liberating hydrogen sulphide, and this passing into the next vessel forms soluble calcium hydrosulphide, which in turn is decomposed by carbon di- oxide, so that a series of interactions is involved as follows : SULPHUR SUMAC 471 S ULPHUR ( Continued) CaS + H 2 O + CO 2 = CaCO 3 + H 2 S CaS + H 2 S =CaS 2 H 2 and CaS 2 H 2 + CO 2 + H 2 O = CaCO 3 + 2H 2 S, the sulphuretted hydrogen so generated, although mixed with atmospheric nitrogen and some carbon dioxide, being rich enough to burn into sulphur dioxide, which is then utilized for making sulphuric acid or otherwise. Sulphur Chlorides Sulphur and chlorine in interaction yield two interesting bodies with the formulae S 2 C1 2 (di- sulphur dichloride) and SC1 2 (sulphur dichloride) ; the first is formed by passing a stream of dry chlorine gas over heated sulphur, when the dichloride distils over as an amber-coloured volatile liquid of unpleasant irritating odour. The other is produced by the same "process con- ducted at a temperature not above o, and is also a dark reddish liquid (much less stable than the dichloride), which has the property of dissolving sulphur with avidity, thus yielding a liquid used in vulcanizing rubber, etc. Sulphur Oxychlorides number four compounds having the formulae SOC1 2 , SO 2 C1 2 , SO 2 C1(HO), and S 2 O 5 C1 2 . The second of these compounds, known variously as sulphuryl chloride and chloro-sulphuric acid, is formed by the direct union of chlorine and sulphur dioxide in bright sunshine and can be otherwise prepared. It is a colourless liquid of sp. gr. i '66 which fumes in moist air, and boils at 70 C. Carbon Disulphide (CS 2 ) is, in the pure state, a colourless, heavy, but mobile liquid of high refractive character and sweetish smell, but as usually prepared it has a most un- pleasant odour. It is very poisonous, highly inflammable, has a sp. gr. of 1-292 at o, boils at 46 C., and is largely used as a solvent. (See p. 88.) SULPHURETTED HYDROGEN See p. 470. SULPHURIC ACID See p. 468. SULPHURIC ACID TUBE See Drying Tube. SULPHUROUS ACID See p. 467. SULPHYDRATES (Hydrosulphides) Potassium hydrosulphide is KHS and calcium hydrosulphide is CaH 2 S 2 . (See Hydrosulphides, p. 258.) SUMAC A tanning material in the form of a powder prepared from the dried leaves and twigs of various shrubs and trees of the Rhus order. It is also used in dyeing and calico- printing. 472 SUNFLOWER OIL-SYLVESTRENE SUNFLOWER OIL (from Helianthus annus) is a pale yellow liquid of sp. gr. 0-924, with a saponification value of 189 to 193, refractive index of 1*461, and iodine value 129 to 132; soluble in alcohol, ether, etc. It is pro- duced in Russia on a considerable scale, some 2,700 square miles being devoted to its cultivation. It is also produced in China, Italy, and India. The seeds yield about 20 to 23 per cent, of the oil, which is said to be as good as olive oil for edible purposes, and is used in making soaps, varnishes, and illuminants. It is a slow-drying oil, and contains the glycerides of oleic, linolic, and palmitic acids. " SUPERB ASIQUE METAL" A modification of cast iron, having a greater resistance to the action of alkaline solutions. " SUPERNEUTRAL METAL" A silicon-iron alloy suitable for the construction of nitric acid condensers, etc. SUPERPHOSPHATE OF LIME is an admixture 'of soluble acid phosphate of calcium (CaH 4 (PO 4 ) 2 ), and is prepared in large quantities for use as a fertilizer by treating phos- phates (such as sombrerite, apatite, and coprolites), bones, etc., with about two-thirds of their weight of sulphuric acid of sp. gr., 1-55 to i -60. The mixture thus produced, is one of calcium sulphate with calcium monophosphate (Ca 3 (PO 4 ) 2 + 2H 2 SO 4 = 2CaS0 4 + CaH 4 (PO 4 ) 2 , but if a larger quantity of sulphuric acid is used the phos- phate is converted into tribasic phosphoric acid, so that the product is of varying composition. Bone charcoal, which has been used for decolourizing purposes as ordinarily prepared, viz., by charring bones, still retains its calcium-phosphate constituents, and can be utilized by this method for the production of " super- phosphate," the total consumption of which amounted in the United Kingdom to 750,000 tons in 1919. There are many grades of phosphates manufactured as fertilizers. The free phosphoric acid in a good super- phosphate should amount to less than i per cent., and the water should not exceed 10 to 12 per cent. The strength is expressed in percentage of P 2 O 5 soluble in water and in ammonium citrate, but 80 per cent, should be soluble in water. SYLVANITE A gold, silver, and tellurium ore ((Ag,Au)Te 2 ) found in Transylvania, Colorado, and elsewhere. SYLVESTRENE (C 10 H 16 ) A terpene, which boils at 175 C, and is the chief constituent of genuine Russian and Swedish SYLVESTRENETAIFUSHI OIL 473 SYLVESTRENE (Continued)- turpentine oils. It gives a fine blue coloration with acetic anhydride and strong sulphuric acid. (See Essential Oils and Terpenes.) SYLVIC ACID A reputed constituent of rosin. SYLVINITE See Potassium. SYMBOLS See Elements, Chemical Interactions, and Formulae. SYMPATHETIC INK See Inks and Cobalt. SYNAPTASE (Emulsin) See Amygdalin. SYNTHESIS The building up, by chemical means, of elements into compounds, or of compound bodies into more complex bodies in other words, the reverse of analysis or decom- position. The production of rust upon iron is an act of synthesis, by which the oxygen and other constituents of the air enter into chemical combination with the iron ; and the formation of verdigris on copper exposed to damp air is another act of synthesis. When hydrogen gas is burned in the air it forms water synthetically, by chemical combination with the atmospheric oxygen. When lime is heated to a certain temperature in a current of carbon-dioxide gas, they enter into combination, forming calcium carbonate by synthesis. Chemists have succeeded in synthetically building up many very complex substances, amongst others urea, acetic acid, acetylene, alcohol, salicylic acid, alizarin, indigotin, etc. SYNTONIN A peptone prepared from muscle fibrin by the action of dilute hydrochloric acid. TAIFUSHI OIL The Oleum gynocavdice (Oleum chaulmoogra) of the Japanese pharmacopoeia, contains as its chief con- stituents glyceryl chaulmoograte and hydnocarpate, and some palmitin, and is surmised to be obtained from the seeds of Hydnocarpus anthelmintica (not from Taraktogenos Kurzii, which is the source of the genuine chaulmoogra oil) . Its sp. gr. is 0-952 ; it melts at 22 C. ; its saponification number is 20-30, and iodine number 85-05. Pure chaulmoogric acid (C 18 H 32 O 2 ) melts at 68 C., has an iodine value of 90-1, and specific rotation of +56; and pure hydnocarpic acid (C 16 H 28 O 2 ) melts at 59 C., has an iodine value of 100*2, and specific rotation +68*1. (See Chaulmoogra Oil.) 474 TALC TANNING TALC A very widely diffused mineral, partly composed of hydrous magnesium silicate. One published analysis gives SiO 2 ... ... ... 63-2 per cent. MgO ... ... ... 28-0 Moisture, etc. ... ... 8-8 i oo-o The more laminated varieties are of considerable utility for making stove-windows, goggles, lamp chimneys and phono- graph diaphragms, being transparent and incombustible. The world's production in 1918 amounted to 296,478 metric tons. Talc powder forms a very nice absorbent basis. (See also French Chalk, Mica, Soap-Stone, and Steatite.) TALLOW The name applied to the harder varieties of fats, such as the suet of the ox and sheep and the vegetable cacao fat. It is separated from the cellular tissue with which it is associated in suet, by melting. Beef tallow has a sp. gr. of 0-943 to '95 2 J a saponifica- tion value of 193 to 200, and an iodine value of 38 to 46. Mutton tallow has a sp. gr. of 0-937 to '953> a saponi- fication value of 192 to 195, and an iodine value of 35 to 46. Tallow, like other fats, consists of a mixture of stearin, palmitin, and olein, in which the harder fats predominate. There is another vegetable tallow, which is extracted from the fruit o'f the Chinese tallow-tree, which is also used in soap-making. (See Fats.) TANNIC ACID or GALLIC ACID (C 7 H 6 O 6 ) is practically another name for tannin, but it would appear that there are a number of tannic acids nearly related but differing to some extent according to their source e.g., kino-tannin, catechu- tannin, coffee-tannin, sumac, etc. Gallo-tannic acid (see Gall Nuts) is a colourless amorphous substance readily soluble in water and yields gallic acid when boiled with dilute acids. A commercial tannic acid is prepared of 55 to 58 per cent, strength. (See Gallic Acid.) TANNING is an important industry, as indicated by the fact that in 1918 about 8 million hides and calf skins of the value of ^"30,000,000 were tanned in the United Kingdom. After soaking to remove blood and lymph, the skins are painted on the fleshy side with a mixture of slaked lime and sodium sulphide or calcium hydrosulphide, and then the wool is pulled, leaving the skin, or " pelt." This, after washing, is passed through a lime liquor, and, after rubbing TANNING TANNINS 475 TANNING (Continued) off the hair, is then subjected to a mechanical operation (fleshing) to remove all adhering flesh, when the skins are ready for " bating," or " puering," to render them soft and supple by removal of hair sheaths, sebaceous glands, muscles, sweat ducts, etc., held together by elastic fibres a process which is of a fermentative character, carried out by dressing with dung. After drenching, the skins are then ready for treatment with the tan liquor, which may be an infusion of sumac ; other tanning materials being barks, gambier, myrobalans, valonia, and extracts, such as kino, and those of oakwood, chestnut, and quebracho. In the process of tanning, the astringent principles enter into combination with the collagen (gelatinous or proteid) part of the skins constituting the fibrous tissues, producing leather. Formaldehyde has been used in tanning, by reason of its coagulating and preservative effect on the collagen molecule. In another process of tanning, chromium salts are used for treatment of the prepared pelts, the bath consisting of a mixture of potassium or sodium dichromate with hydrochloric or sulphuric acid, followed by the application of sodium thiosulphate to effect the reduction of the chromium salt to a basic state or oxide in combination with the tissue. It is stated that after unhairing and pick- ling by immersion in a bath of dilute sulphuric acid and sodium chloride, skins can be completely tanned in two days by immersion in a bath of chrome liquor, consisting of basic chromic sulphate diluted to contain 17 grms. of chromic oxide per litre. The impregnation of the materials to be tanned is sometimes effected by a process of electric endosmose, which is said to be applicable to the impregna- nation with chromium or other metallic salts, of fabrics which have been treated with glue or gelatin, and that this method permits of the utilization of very dilute tanning liquors and greatly facilitates the process in point of time. TANNINS Astringent principles of the bark and some other parts of certain trees (such as the chestnut, oak, hemlock, larch, quebracho, osage, mimosa, sumac, and eucalyptus) which combine with albumen and gelatine, as occurring in animal hides, to form leather. In Australia, wattle bark is the principal tanning agent employed by tanners, that of the golden wattle (Acacia pycnantha) and the black or green wattle (A. decurrens) being two of the more important 476 TANNINS TAR ACIDS TANNINS (Continued) varieties. A valuable tan bark is yielded by the mallee (Eucalyptus Occident alis). The astringent principle common to cutch and mimosa extract is either a glucoside or associated with a substance of that nature, as they both yield an unfermentable sugar upon hydrolysis. It has become customary to determine as tannin that portion of the water-soluble constituents of vegetable materials which will precipitate gelatin from solution, and which will form compounds with hide fibre, which are resistant to washing. (See Cutch, Gambier, Mimosa, Sumac, and Gall Nuts.) TANSY OIL Distilled from the herb Tanacetum vulgare, and containing thujone, camphor, borneol, etc. It is a yellowish, thin oil of poisonous character, which rapidly darkens upon exposure to the air ; is soluble in alcohol and ether ; has a sp. gr. of 0*925 to 0-955 5 an d is usec ^ m medicine and per- fumery. TANTALITE A rare mineral, consisting of iron and man- ganese tantalate ((FeMn)Ta 2 O 6 ), generally containing some columbium. TANTALUM (Ta) Atomic weight, 181-5; sp. gr., 16-8. Tanta- lum is a rare metallic element found in nature in association with another rare element (niobium) in a number of Austra- lian and Swedish minerals, including columbite and tantalite. It is a little darker than platinum; is nearly related to vanadium ; has a very high melting-point about 2,900 C. ; and is chiefly used in making electric lamp filaments. It is not attacked by acids ; it combines with carbon to form carbides, and at a red heat combines with hydrogen, nitrogen, and chlorine. Two insoluble oxides (Ta 2 O 4 and Ta 2 O 5 ) are known, and a number of compounds corre- sponding to the phosphates. The metal is made by heating the double fluoride of tantalum and potassium in an electric furnace. "TANTIRON" A hard and brittle brand of acid-resisting silicon-iron alloy. TAPIOCA A starchy body, useful as food, obtained from the roots ofjanipha Manihot, cultivated in the West Indies. TAR See Coal and Wood. TAR ACIDS A common designation for mixtures of phenol (carbolic acid) with cresols, and used in respect of all con- stituents of such liquids as may be combined with and extracted by means of caustic soda or other alkali. (See Carbolic and Cresylic Acids.) TARAXACUM OFFICINALE TEA 477 TARAXACUM OFFICINALE or DANDELION Extract or in- fusion of dandelion (Leontodon taraxacum), containing an active principle named taraxacin, and used as a laxative. TARRAGON OIL A nearly colourless liquid, distilled from Artemisia dracunculus -, sp. gr., 0*900 to 0^949; optical rotation, + 2 to + 9 ; and refractive index, 1*5161 to 1*517 ; soluble in alcohol and ether, and used in medicine and for flavouring, TARTAR A name applied generally to salts of tartaric acid, but more particularly to the acid potassium tartrate (KHC 4 H 4 O 6 ) which is deposited from fermenting grape juice and wines on long keeping. This is known in com- merce as "crude tartar " or "argol," and gives "cream of tartar" when purified by being dissolved in water and re- crystallized. TARTAR EMETIC See Antimony, p. 35. TARTARIC ACID (C 4 H 6 O 6 ) occurs in nature either in the free state or in combination with potassium and calcium as tartrates, in many vegetable juices such as tamarinds, girkins, mulberries, pineapples, and more particularly in grape juice in combination as acid tartrate of potassium. (See Tartar.) It is readily prepared in a crystalline state from the last-named substance or crude argols. (See Argol.) Tartaric acid crystallizes in large prisms, which are soluble in water. It fuses at 170 C. ; is decomposed at 1 80 C. ; and is used in calico-printing as a solvent for the mordant and finds applications in medicine. Tartaric acid is known in four distinct modifications. (See Racemic Acid.) TAURINE (C 2 H 7 NSO 3 ) A crystalline body somewhat soluble in water, found present in the faeces and easily obtained by the action of acids upon bile. TAURpCHOLIC ACID (C 6 H 45 NSO 7 ) A constituent of bile which is decomposed by boiling with acids, yielding cholic acid and taurine : C 26 H 45 NSO 7 + H 2 O = C^H^Og (cholic acid) + C 2 H 7 NSO 3 (taurine). (See Bile.) TEA The dried leaves of the tea-plant Thea sinensis, which is largely cultivated in China, Japan, India, and Ceylon. It contains an essential oil (which gives aroma to it), an active principle named theine or caffeine (C 8 H 10 N 4 O 2 ), legumin 47& TEA TELLURIUM TEA (Continued) and tannin, in varying proportions according to the nature of the tea and other circumstances attending its production. The amount of theine varies between and i\ per cent., the tannin between 12 and 15 per cent., and the essential oil from J to i per cent. Taken in moderation, tea is a useful stimulant. TEA-SEED OIL is expressed from the seeds of Camellia theifera, and is a clear, straw-coloured, yellowish oil, without odour or taste, closely resembling olive oil, for which it is used as an adulterant, although owing to the presence of a poisonous saponin body, it has been condemned as an edible oil. Although botanically related to the plant from which tea is prepared, the two things are quite distinct. There are several varieties on the market, and the Sasanqua oil has a sp. gr. of 0*916 to 0*919, a saponifica- tion value of about 193*4 to 194, and an iodine value of 817 to 82*3. The Thea japonica yields Tsubaki oil, which is very similar to tea-seed oil. TELEGRAPH See Electricity. TELEPHONE See Electricity. TELESCOPE An instrument formed of several lenses so arranged as to magnify distant objects, TELLURIUM (Te) Atomic weight, 127*5; S P- g r -> 6<2 5 5 melting-point, 525 C. An element which occurs natur- ally to some small extent in pure crystalline form, but is for the most part met with in combination in some rare minerals including telluvite (TeO 2 ), tetradymite (bismuth telluride, Bi 2 Te 3 ), and sylvanite ((Ag,Au)Te 2 ). It is also said to exist in mineral forms associated with gold in Hungary and Transylvania. It is a bright white metal of lustrous appearance which is soluble in nitric and sulphuric acids and potassium hydroxide. It is a poor conductor of heat and electricity, and when heated in the air, burns with a blue flame, forming the dioxide (TeO 2 ). The metal can be prepared from bismuth telluride (Bi 2 Te 3 ) by fusion with sodium carbonate and carbon and treatment of the resulting product with water, which gives a solution of sodium telluride and sodium sulphide, and upon exposure to the air the metallic tellurium is deposited as a grey powder, which can be purified by dis- tillation in a current of hydrogen gas. It is also obtained TELLURIUM TERPENES 479 TELLURIUM (Continued) by reduction of tellurium dioxide. It is used in the ceramic industries. In combination with hydrogen it forms hydrogen telluride (H 2 Te), an offensive poisonous gas soluble in water which is decomposed by heat and deposits metallic tellurium as a crystalline sublimate. Two oxides are known (TeO 2 and TeO 3 ) and two cor- responding acids, known as tellurous (H 2 TeO 3 ) and telluric (H 2 TeO 4 ) acids, analogous to sulphurous and sulphuric acids. Two chlorides are known (TeCl 2 and TeCl 4 ) and cor- responding bromides and iodides. It will be seen that in general properties, tellurium re- sembles sulphur and selenium. TEMPERATURES (Notable) See Heat, p. 242. TEMPERING The tempering of' steel is brought about by heating and slow cooling. TENSION (of Gases) The force with which the particles or molecules tend to recede apart and to occupy a greater space. (See Gases.) TERBIUM (Tb) Atomic weight, 159-2. A rare element contained in gadolinite, samarskite, euxonite, and monazite. Two oxides (Tb 2 3 and Tb 4 O 7 ), a sulphate (Tb 2 (SO 4 ) 3 ), chloride (TbCl), and nitrate (Tb(NO 3 )) are known, the salts being hygroscopic and crystalline. TEREBENE American or French turpentine after heating moderately with several successive small quantities of strong sulphuric acid until its action on polarized light is quite destroyed, and then, after washing, submitted to distillation. It is a mixture of hydrocarbons, of which inactive camphene is one and dipentene (C 5 H 8 ) another. TEREPHTHALIC ACID (C 6 H 6 O 4 ) An oxidation product of turpentine and cymene, nearly insoluble in water and alcohol, which sublimes unchanged. TERPENES (C 10 H 16 ) A series of isomeric liquid hydrocarbons of the formula C 10 H 16 , having boiling-points ranging from 160 to 190 C., but as they exist in essential or ethereal oils they are mixtures of terpenes and not chemical indi- viduals, and are often associated with oxidized bodies allied to and, in many cases, derived from them. Pinene (dextro- 48o TERPENES-TERPINENE TERPENES (Continued) pinene) is the chief terpene contained in the American and German turpentine oils, laevo-pinene is the chief constituent of French turpentine, whilst sylvestrene and hemi-terpene, or dipentene (C 5 H 8 ), together with pinene, are contained in varying proportions in the Russian and Swedish oils. Indian turpentine contains pinene and two new terpenes named carene and longifolene. Oil of orange contains limonene. Fennel oil and some eucalyptus oils contain phellandrene. Dextro-pinene rotates the polarized ray to the right and laevo-pinene to the left. Citrene is contained in the oil of citron, hesperidene in the oil of orange, thymene in the oil of thyme, carvene in the oil of cumin, and these terpenes have the formula C 10 H 16 , and approximately the same boiling-point viz., 1 60 to 190 C. ; but for the most part they are mixtures of isomeric compounds, and all are liquid with the exception of camphene. The terpenes form additive compounds, such as the dihydrochlorides, C 10 H 18 C1 2 ; tetrabromides, C 10 H 16 Br 4 ; nitroso-chlorides, C^K^MOd)^ etc., most of which are well-defined crystalline compounds with definite melting- points. All the terpenes also yield peroxide of hydrogen when air-oxidized in the presence of water. Isoprene is the best-known hemi-terpene (C 5 Hg), whilst dipentene is associated with cineol in Oleum cina, and can be easily prepared from pinene and some other terpenes. These compounds are further referred to in the descrip- tions of the various essential oils in which they occur or under their distinct names. Another associated class of hydrocarbons Oi the formula Ci 5 H 24 are termed " sesquiterpenes." (See also Essential Oils.) TEEPIN HYDRATE (C 10 H 2a O 3 or C ;0 H 20 O 2 ,H 2 O) is a colour- less, crystalline substance which is soluble in alcohol and ether, melts at 116 C., and is a combination of water with a substance named terpin, which in its turn is pre- pared by boiling terpineol (C 10 H 18 O) with dilute sulphuric acid. It is prepared from oil of turpentine by the action of an alcoholic solution of nitric acid. TERPINENE A terpene (C 10 H 16 ) obtained by the action of alcoholic sulphuric acid on dipentene. It boils at 179 C., and is optically inactive. TERPINEOLTHA LLI UM 48 1 TERPINEOL (C 10 H 18 O or C 10 H 17 OH) is a kind of liquid alcohol allied slightly in chemical nature to menthol and carvone, the last-named substance being the chief con- stituent of the oil of caraway-seeds. It is stereo-isomeric with geraniol, and occurs naturally to some extent ; is readily made from terpin hydrate by the action of dilute acid, and is extensively used in the synthetic perfumes industry, being the basis of the lilac and lily artificial pro- ducts. It melts at 37 C., boils at 210 C., and is soluble in alcohol and ether. TERPINOLENE A terpene which boils at 183 to 185 C. TERRA ALBA of commerce is variously kaolin, gypsum, burnt alum, or magnesia, but the term should be reserved for kaolin. TERRA GOTTA Baked earth or clay. TEST-PAPERS Absorbent papers impregnated with litmus for testing alkalinity or acidity of fluids. (See Litmus and Turmeric Paper.) TEST-TUBES are thin glass tubes of special quality and various diameters ranging from about J inch to i inch, sealed at the lower end, and sometimes provided with a lip at the upper end. (Illustrations of them will be found under the headings of Pneumatic Trough and Voltameter.) They are chiefly employed, as implied by their name, for making chemical tests, and are capable, when containing liquids, of withstanding the direct application of flame, such as that of a Bunsen burner. TETRADYMITE See Bismuth. TETRAHEDRITE (Grey Copper Ore) A mineral compound of copper-antimony and other sulphides containing about 52 per cent, of copper. "TETRALIN" (Tetra-hydro-naphthalene C 10 H 12 )A liquid of pungent odour produced by the hydrogenization of naphthalene in the presence of a catalyst and used as a solvent of waxes, resins, rubber, etc., and substitute for turpentine in varnish and polish making. (Compare " Dekaline.") TETRATHIONIC ACID See Sulphur (Oxides). THALLIUM (Tl) and its Compounds Atomic weight, 204 ; sp. gr., 11-85; melting-point, 294 C. An element present in many varieties of iron and copper pyrites so that it can be obtained from the dust resulting from the roasting of 482 THA LL1 UMTHEINE THALLIUM (Continued) pyrites when used for the manufacture of sulphuric acid. In a recently reported case, 4 Ibs. of thallium was recovered from 1,500 tons of pyrites, the dust containing 0^25 per cent., equal to i part thallium per 1,000,000 parts of pyrites. It is also found in association with copper, selenium, and silver in the rare mineral named crookesite. It is obtained from the sulphate by dipping strips of zinc in the solution, when the thallium is deposited upon the zinc in the form of a spongy crystalline mass ; also by treating thallium iodide with metallic sodium. It is bluish-white in colour, soft, heavy, soluble in nitric and sulphuric acids, makes a mark on paper as lead does, and is intermediate in properties between lead and the alkaline metals. By reason of the fact that it undergoes oxidation in the air to black thallous oxide, it has to be preserved in water to keep its normal bluish-white lustre. There are two oxides, thallous oxide (T1 2 O) and thallic oxide (T1^O 3 ), the latter being a dark reddish powder, insoluble in water, formed when the metal is melted in presence of air. Thallous Hydroxide (T1HO) is produced by dissolving thallous oxide in water, or by adding a solution of barium hydroxide to one of thallous sulphate, and concentrating the filtrate from the precipitated barium sulphate. It then crystallizes in yellow needle-shaped form. It is soluble in water and alkaline in reaction. Thallous Chloride (T1C1) A white soluble substance formed when metallic thallium is heated (when it burns) in chlorine gas ; and there is another chloride (TC1 3 ), a colour- less body obtained by passing chlorine through water con- taining thallous chloride in suspension, and concentration of the resulting solution, when it crystallizes out in com- bination with water (T1C1 3 ,2H 2 O). Thallous Carbonate (Tl 2 CO y ) is a crystalline body soluble in water. Thallous Phosphate (T1 3 PO 4 ) is obtained by precipitating a thallous solution with one of potassium phosphate. The Sulphide (T1 2 S) is an insoluble black compound. THEBAINE (Para-morphine) (C 19 H 21 NO 3 ) an alkaloidal base, being morphine in which both phenolic and alcoholic hydroxyls are methylated. It is a white, crystalline, and very poisonous substance, soluble in water and alcohol. THEINE An alkaloid, otherwise known as caffeine (C 8 H 10 N 4 O 2 , H 2 O). (See Caffeine and Tea.) THEN A RDITE THERMOMETERS 483 THEN AEDITE Natural anhydrous sodium sulphate (Na 2 SO 4 ). THEOBROMINE (C 7 H 8 N 4 O 2 ) A white, crystalline, poisonous drug of bitter taste, being the active principle of cacao- beans, and nearly allied in chemical constitution to caffeine, which can be produced from it by replacing an atom of hydrogen by the radical methyl. It is soluble in chloro- form, but not in water or alcohol, and has a melting-point of 329 C. THEORY A reasonable systematic view of ascertained facts or a philosophical explanation of known phenomena not so conjectural as an hypothesis. THERM The name given to 100,000 heat units by Parliament as the new basis of coal-gas charges. " THERM ALINE " A German mixture of calcium carbide and crude oil in sawdust, which upon addition of water yields a mixture of fuel gases, consisting of acetylene and the vapour generated by the burning crude oil. The mixed gases are claimed to show advantages as a fuel for high temperatures. THERMAL UNIT See Heat, p. 244. " THERMIT" PROCESS When a mixture (thermit) of metal- lic aluminium powder and ferric oxide is subjected to ignition by a fuse or otherwise, the whole mass becomes incandescent, the aluminium combining with the oxygen of the iron oxide, and setting free the molten iron, which forms a layer below. The temperature realized in this process is estimated at about 3,500 C., and being high enough to melt all known metals, the process is utilized, among other applications, for the repair of broken castings and joining up the ends of tramway rails without removal. For this latter purpose, a mould is placed round the rail-ends in such wise as to receive a charge of the molten iron, the excess metal being afterwards cut away or otherwise removed as required. THERMOLYSIS A term sometimes used to express dissocia- tion of chemical compounds under the influence of heat. (See Dissociation.) THERMOMETERS Instruments used to ascertain or register temperatures or degrees of heat, constructed upon the principle of the expansion of fluids by heat. Mercury is the fluid usually employed, but alcohol is used for low temperatures. For a description of the various scales employed see Heat, p. 241. 484 THERMOSTAT THORIUM THERMOSTAT An apparatus designed to maintain a constant temperature. THINNERS See Paints. THIO-ACIDS (Sulpho- Acids) Compounds analogous to oxy- acids in which the oxygen is replaced by sulphur. TfflOCYANIDES See Sulphocyanides. THIOLS Mercaptans. THISTLE-FUNNEL A tube with small funnel-head by means of which a liquid can be conveyed into any vessel with which it may be connected. (See p. 219.) THORIANITE A heavy black mineral containing thoria mixed with uranium oxides, etc., found in Ceylon. It usually occurs in small cubes, has a sp. gr. of 9-5, and is amorphous with pitch-blende. THORITE A mineral consisting essentially of silicate of thorium, yellow to dark brown in colour, and of sp. gr. 4*4 to 5*4 ; found chiefly in Ceylon. THORIUM (Th) Atomic weight, 232-5; sp. gr., about n ; melting-point not definitely ascertained, but above 1,700 C. It is a rare metal occurring in the minerals thorite, thorianite, orangcite, and monazite, and in the form of an oxide is used in the preparation of mantles for use with incandescent gas burners. The purer thorium compounds are worked up from the raw material called monazite sand, which is essentially a phosphate of the cerium earths and occurs naturally in extensive deposits in Carolina, the coast of Brazil, and Travancore. The separated monazite from the Travancore deposits contains about 8J per cent, of thoria, as compared with 6 per cent, in the best concentrates from the Brazilian sands. Thorium is obtained by heating the double chloride of thorium and potassium with metallic sodium, and as thus produced is a grey, dense, almost infusible powder. It is soluble in dilute hydrochloric and sulphuric acids, and is known in both crystalline and amorphous forms. Two oxides insoluble in water (ThO 2 and Th 2 O 7 ) are known; also a chloride (ThCl 4 j, and a white, crystalline nitrate (Th(NO 3 ) 4 i2H 2 O), both of which are soluble in water; also other compounds, which generally resemble those of cerium. Meso-Thorium, one of ten radio-active disintegration products of thorium; exhibits properties similar to those of radium. It is a regular by-product of the American manufacture of gas mantles from monazite sand, and is said THORIUM-THYMOL 485 THORIUM (Continued) to be specially adapted for luminous paint in respect of articles required for comparatively short periods. (See also Ionium.) THUJA OIL Distilled from the leaves of the white cedar (Thuja occidentalis), containing ^-pinene, /-fenchone, and thujone; sp. gr., 0*915 to 0-925; soluble in alcohol, ether, etc., and used in medicine. THUJONE A ketone contained in thuja oil and the oils of tansy and wormwood, its formula being variously given as C 10 H 16 and C 10 H 18 O. THULIUM (Tm) Atomic weight, 168-5. A rare element of the yttrium group identified by its spectrum and found in association with yttria in a number of minerals, in- cluding gadoliniUj keilhanite, euxenite, and samarskite. THYME OIL The red variety of thyme oil obtained from garden thyme (Thymus vulgaris L.) by distillation with water. A pound of thyme yields from 20 to 90 grains of oil. It contains the phenolic body carvacrol (C 10 H 14 O), which is isomeric with thymol, but, according to some statements, no thymol, and has a pleasant odour and camphoraceous taste ; sp. gr., 0-9 to 0-95. It is stated to contain usually about 40 per cent, of phenols, but the richest oils are distilled from the Andalusian Covydothymus capitatus, the phenols ranging from 55 to upwards of 67 per cent. The genuine thyme or origanum oil is stated to contain 50 per cent, thymol associated with a terpene named thymene (C^H,.) and the hydrocarbon cymene (C 10 H 14 ). (See Origanum Oil and Thymol.) THYMOL (C 10 H 14 O), a homologue of phenol, is a white crystalline substance of mild, pleasant odour found present in origanum oil, also in the volatile oil of horsemint (monarda oil) and in oil of ajowan, as obtained from the fruit of the herb Ptychotis ajowan, which is grown in Persia, Egypt, and India. It is but slightly soluble in water, dissolves readily in alcohol and ether, and is a valuable antiseptic and preservative. It melts at 49 C. Recent chemical investigations appear to indicate that the best source of thymol in the future will be the ketone named piperitone, which is contained in the oil yielded by the Eucalyptus dives and from which it can be made by a re- duction process. It can also be made synthetically from cymene. 4&6 THYMOL Tltt THYMOL (Continued) The percentages of thymol in various essential oils have been reported as follows : Ajowan oil ... ... ... 40 to 50 Thymus vulgaris ... ... ... 20 to 30 Monarda punctata ... ... ... 60 Carum copticum ... ... ... 45 to 55 Ocimitm viride ... ... ... 37 Origanum hirtum from Crete and Dalmatia ... ... ... 60 to 67 Moslajaponica .. ... ... 44 Wild thyme of France ... ... 20 "TIMONOX" A proprietary brand of a white oxide of antimony, claimed to possess the essential requirements of a first-class pigment, having good oil-absorption, great opacity, and easily ground with oil. TIN (Stannum, Sn) and its Compounds Atomic weight, 118; sp. gr., 7'2 ; melting-point, 232 C. Tin is found in nature for the most part in the form of oxide (SnO 2 ) in the mineral known as tin-stone (cassiterite) in Cornwall, the production in 1890 amounting to 15,000 tons, but only to 6,378 tons in 1918; it also occurs in Malacca, Bolivia, Borneo, and Mexico. The metal is prepared from it, after washing, by a process of calcination with anthracite coal, whereby the oxygen constituent is removed in the form of carbon monoxide and the metal remains behind in the form known as block tin Tin is a bright white metal which can be obtained in crystalline form, and does not tarnish in the air. It is fairly soft, ductile, and malleable. In cold dilute nitric acid it dissolves, stannous nitrate (4Sn(NO 3 )o) being formed, while the corresponding chloride is formed by the action of strong hydrochloric acid upon the metal. It is largely used in the process of tinning iron and other metals, ordinary tin-plate consisting, for example, of sheet- iron coated with tin on the surface by dipping the cleaned iron plates into the molten tin. It has valuable applications by reason of the fact that it is not acted upon by many chemicals which readily attack iron and some other metals. It enters into the composition of many alloys, including solder, brasses, and bronzes. Britannia metal is some- times made of 84 parts tin, 10 parts antimony, 4 parts flN AND ITS COMPOUNDS 4^7 TIN (Continued) copper, and 2 parts bismuth, whilst pewter consists of 4 parts tin and i part lead. When strongly heated in the air, tin takes fire and forms stannic oxide (SnO 2 ), which is also known as "putty powder " a white, insoluble, amorphous substance which turns yellow on heating, and is not acted upon by acids or alkalies. It is used as a polishing-powder for steel and glass, and in the manufacture of certain kinds of glass. The lower (stannous) oxide (SnO) can be prepared by heating the oxalate out of contact with air, or in a hydrated form (2SnOH 2 O) by adding a solution of sodium carbonate to one of stannous chloride. It is soluble in acids, forming stannous salts, and when heated in the air, it becomes peroxidized to SnO 2 . The hydroxide dissolved in sodium hydrate is used by calico printers under the name of " sodium stannite." Stannic Acid (SnH 2 O 3 ) is obtained in hydrated form by adding a solution of calcium carbonate to one of stannic chloride in insufficient quantity for complete precipitation, and, as thus produced, is a white gelatinous body which forms a number of salts, including potassium and sodium stannates, the last named being used as a mordant under the name of " tin preparing salt," and made by fusing metastannic acid with caustic soda. Stannous Chloride (SnCl 2 ), a white, crystalline body soluble in water, obtained by dissolving tin in hydro- chloric acid, is also employed as so-called "tin salts" by calico printers and dyers and in tin galvanizing. Stannous Chromate (SnCrOJ, an insoluble substance, is used in decorating porcelain. Stannous Sulphate (SnSO 4 ), a heavy, white, crystalline powder, soluble in water, is used in dyeing. Stannic Chloride (SnCl 4 ) is obtained by the action of chlorine gas on the metal, also by passing chlorine in excess through a solution of stannous chloride. In the pure an- hydrous state, it is a colourless liquid which boils at 120 C., fumes in the air, and forms several hydrates with water. One of these viz., SnCl 4 5H 2 O is crystalline, soluble in water, and is also used as a mordant, but for that purpose it is more usually prepared by dissolving tin in cold aqua regia, when it is commercially known as "oxymuriate of tin." Stannous Sulphide (SnS) is formed when tinfoil is intro- duced into the vapour of sulphur ; the metal then fires and forms the leaden-coloured stannous sulphide. 488 TIN TIT A NI UM TIN (Continued) Stannic Sulphide (SnS 2 ) is a bright yellow crystalline powder used as a pigment for imitation gilding under the name of " mosaic gold," and is obtained as the resuty of complicated changes by heating tin amalgam with sulphur and ammonium chloride in a retort. It is soluble in alkaline sulphide solutions and can be sublimed to some extent. When a solution of gold chloride is added to a dilute solution of stannous chloride a splendid purple colour is produced, and this is a distinguishing test for tin. (See Purple of Cassius.) Stannic Phosphide (Sn 2 P 2 ), made by heating the metal together with phosphorus, is a silver-white compound, used in the manufacture of phosphor-bronze. TINCAL See Boron. TINPLATE See Tin. TITANIUM (Ti) Atomic weight, 48-1 ; sp. gr., 4-5; melting- point, i, 800 C. Titanium is a rare element occurring in several mineral forms (rutile, brookite, and anastase), and finds some employment in metallurgy. It is obtained as a dark grey, amorphous powder by heating titanous chloride with metallic sodium, and exhibits a tendency to combine directly with nitrogen, forming a nitride. It is soluble in acids, resembles tin in many of its properties, and forms two oxides (TiO and TiO 2 ), which are insoluble in water and are used in the preparation of enamels to make them more resistant to corrosion. Titanous Chloride (TiCl 3 ) is used commercially in con- nection with the dyeing of cotton goods, when over-dyeing has occurred and require " stripping " before re-dyeing. Titanium Oxalate (Ti 2 (C 2 O 4 ) 3 .ioH 2 O) is a yellow, crys- talline salt, soluble in water, used as a mordant in textile dyeing. Titanium Sulphates (Ti 2 (SO 4 ) 3 and Ti 2 (SO 4 ) 2 9H 2 O) are both soluble in water and used as mordants. Titanium Tetrachloride (TiCl 4 ), a colourless liquid of sp. gr. 4*59, soluble in water, is also used in association with potassium bitartrate as a mordant. Extensive deposits of titanium ore are found in the New World, Africa, Australia, Scandinavia, and in the Urals, and the growing importance of titanium dioxide as a pigment has led to a process being worked out in Norway for the production of this compound on a considerable scale from ilmenite (titaniferous iron ore). As compared TITANIUM TOPAZ 489 TITANIUM (Continued) with white-lead and zinc oxide, "titanium white" offers considerable advantages, possessing, it is said, a greater covering power, being non-poisonous, chemically inert, without saponifying action upon linseed oil, while it does not blacken upon exposure. TITRATION The process of making a volumetric deter- mination or analysis by the use of a standard solution. (See Burette, Reagents, and Volumetric Analyses,) TOBACCO The leaf of the Nicotiana tabac^^m t indigenous in America, and extensively cultivated in many countries. Its chief active principle is nicotine (C 10 H 14 N 2 ), which is present to the extent of from about J to 8 per cent., and a smaller quantity of another alkaloidal poison named nicotianine. The leaves contain, also, a large amount of extractives, albuminous bodies, some resin, and mineral salts which constitute ihe ash left upon burning (18 to 23 per cent.). (See Nicotine.) TOLU See Balsams. TOLUENE or METHYL BENZENE (Toluol) (C 7 H 8 or C 6 H 5 CH 3 ) An aromatic hydrocarbon of sp. gr. 0*8613, being a benzene derivative which boils at 110 C. and is soluble in alcohol, ether, and benzene. It finds use as a solvent, as a material from which a number of dyes are manufactured, and in the preparation of "T.N.T." explosive and dyestuffs. (See Coal and Explosives.) TOLUIDINE (C 7 H 9 N) exists in three isomeric forms. The solid para compound is a white, lustrous substance (con- tained in commercial aniline) which melts at 43 C., and from which many red and violet dyes are prepared. The ortho and meta compounds are liquids, which boil at about 199 C. TOLUOL (Toluole) A commercial form of toluene, obtained from the distillation of coal tar. (See Coal.) It is also found in certain natural petroleums and can be produced by " cracking " these mineral oils. (See Toluene and Petroleum.) TONKA-BEANS or TO NQUIN- BEANS The fruit of Dipterix odorata and other D. species, indigenous in Guiana, con- taining coumarin and other substances. It is used in perfumery. TOPAZ A silicated aluminous mineral containing fluorine in combination, occurring in gneiss or granite (5(Al 2 O 3 .SiO 2 ) + Al 2 F 6 .SiF 4 ). The best crystals come from Brazil, and are used for making gems. 490 TORRICELLIAN VACUUM TRIPHENYLMETHANE TORRICELLIAN VACUUM The space above the mercury in a barometer. TOURMALINE The name given to a group of rhombohedral double silicates of colours varying according to their com- position, and usually found in granite, gneiss, or mica-slate. When a crystal of tourmaline is heated to about 150 C. it becomes strongly electrical. TOXIC Poisonous ; property of toxins. (See Toxalbumins in Addenda.) TOXINS or TOXINES Poisonous substances produced in dead bodies and putrid animal tissues. (See Ptomaines.) TRAGACANTH See Gums. TRANSLUCENT Pellucid, clear, transparent. TRANSMUTATION See Elements and Radio-activity. TRANSPARENT Admitting the passage of light ; easily seen through. TREACLE See Molasses. TRI ACETINE (C 3 H 5 (CH 3 CC>9) 3 A glyceride prepared by heating glycerol with acetic anhydride in presence of finely divided hydrogen potassium sulphate. It is used for gelatinizing and lowering the freezing-point of nitro- glycerine. Its sp. gr. is 1*1603 at I 5 C. ; it boils at 258 C., and is miscible with alcohol, ether, chloroform, and benzine. It is a narcotic and is poisonous. TRICHLORACETIC ACID (CC1 3 COOH) A deliquescent, colourless, crystalline compound made by the action of chlorine upon glacial acetic acid ; used in medicine and for removing corns and warts. It melts at 573 C. and boils at 195 C. TRICHLORETHYLENE (C 2 HC1 3 ) is a liquid which boils at 88 C. and is used for the extraction of oil-seeds and bones. TRIDYMITE A rare mineral form of crystalline silica, fre- quently occurring in volcanic rocks. TRI-ETHYLAMNE See Amines. TRI-METHYLAMINE See Amines. TRI-NITRO-GLYCERINE See Explosives. TRI-NITRO-TOLUOL See Explosives. TRIONAL or METHYL SULPHONAL (CH 3 (C 2 H 5 )C(SO 2 C 2 H 5 ) 2 = C 8 H 18 S 2 O 4 ) A crystalline soporific and hypnotic, soluble in water, alcohol, and ether ; melting-point, 76 C. TRIPHENYLMETHANE (CH(C 6 H 5 ) 3 ) is a colourless crystal- line substance which melts at 93 C., boils at 359 C., and TRIPHENYLMETHANE-TUNG OIL 491 TRIPHENYLMETHANE (Continued) is readily soluble in hot alcohol, ether, and benzene. Its derivatives include the malachite green, rosaniline, aurine, and the eosin groups of dyes. TRIPHENYL PHOSPHATE ((C 6 H 5 ) 3 PO 4 ) A colourless and somewhat* deliquescent crystalline substance used as a camphor substitute in making " dope " and impregnating roofing paper, etc. It melts at 53 C., boils at 245 C., and is soluble in alcohol, acetone, ether, and benzene. TRIPOLI An impalpable siliceous earth resulting from the natural decomposition of chert or siliceous limestone, and used as an abrasive and polishing-powder. When pure it is white, and most of the grains are less than 0*01 mm. in diameter. TRIPOLITE See Kieselguhr. TRITURATION Grinding to a very fine powder. TRONA Natural deposits of sodium sesquicarbonate mixed with potassium and boron salts occurring in Egypt, Africa, the United States, and South America. TRYPSIN An enzyme contained in the pancreas, capable of changing albuminous matters into so-called albumoses, in which partially hydrolysed and more soluble state they be- come converted into peptone. (See Enzymes and Peptones.) TUNA OIL See Fish Oils. TUNG OIL (Chinese Wood Oil, Hankow Wood Oil) is ob- tained by pressure from the seeds of Aleurites cordata and A . fordii, indigenous in China and Japan. It is also ex- pressed in Madagascar and known there as bakoby oil. It is yellow in colour, of drying character, composed of glycerides, of unpleasant odour, and liable to solidify when kept. Its sp. gr. is 0-9360 to 0-943 J saponifica- tion value, 190 to 195 ; iodine value, 150 to 165 ; and refractive index, 1*503. It comes to the market in various grades of colour colourless, black, yellow, etc. and is used as a water- proofing material for paper, and in making varnishes, driers, and linoleum. It contains a proportion of free fatty acids, varying from 2 to 4-6 per cent., but for varnish- making it should be prepared so that this content does not exceed i per cent. It is frequently adulterated with cotton-seed and soya-bean oils, etc. When heated to 250 C. for a short time it forms a jelly, due to polymerization, a characteristic not so strongly exhibited by any other glyceride. In China and Japan it is used for varnishing wood and caulking boats. 492 TUNGSTEN TUNGSTEN (Wolfram) (W) Atomic weight, 184; sp. gr., 1877; melting-point about 3,267 to 3,350 C. ; a hard, grey, heavy, ductile metal of great tensile strength, highly prized for use in hardening and toughening steel as specially made for high-speed metal-cutting tools and for making the filaments of incandescent electric lamps. Ror this latter application, the powdered metal is fused or sintered together by the passage of an electric current, the tensile strength of the finished wire of o'oon inch diameter being given as 270 tons per square inch. It occurs in nature as wolfram (wolframite) and scheelite, the former term being often used to cover all minerals in which tungsten tri-oxide is combined with the protoxides of iron and manganese. They vary widely in proportion, and are found chiefly in proximity to, or mixed with, tin ores. Wolframite is heavy, black, and of great specific gravity (7'o), so that it can be easily concentrated from the associated gangue, but not so easily from tin oxide (cassiterite) - } as, how- ever, it is feebly magnetic, while the cassiterite is not, this property can be used to effect separation when associated. Deposits are found in China, Japan, Chili, Peru, and Argentine, the Chinese deposits (in the Kwangsi and Qwan- tung Provinces) being reported as large. A small sample of ore from the Waichow district recently analyzed, was found to contain 55*84 per cent, tungsten, 13*25 per cent, iron, and 11*56 per cent, manganese. Scheelite, or calcium tungstate (CaWO 4 ), is a heavy yellowish or brown-purple mineral, of wax-like appearance, and the supply is small as compared with wolframite. It is chiefly used in the manufacture of ferro-tungsten, on account of the practical difficulties experienced in isolating the oxide in order to prepare the pure metallic tungsten. Supplies come from the United States, Bolivia, Portugal, Burma, Malaya, Australia, New Zealand, and Cornwall. Above one-half of the natural supplies of tungsten ores is mined in the British Empire, a large proportion of the 302 tons of metal produced in 1918 having been obtained from tin mines, and 95 per cent, of the total ores was used in the production of high-speed tool and other alloy steels containing tungsten in proportions varying from 2 to 20 per cent, according to the application. The direct reduction of the ores which yields ferro- tungsten suitable for most purposes is effected by mixing the ore concentrates with anthracite and roasting in an open furnace, i ton of 98^5 per cent, metal being yielded by 2 tons of the purer concentrates. To prepare the metallic powder TUNGSTEN TURMERIC PAPER 493 TUNGSTEN (Continued) the tungstic oxide (WO 3 ) has to be isolated from associated matters, and this can only be done by chemical processes involving the application of mineral acids or fusion with alkali, both methods being employed in practice. The acid attack is designed to dissolve out the iron, manganese, and other oxides, leaving the WO 3 as an insoluble residue ; whereas, by furnacing with soda ash, tungstate of sodium is produced, and from this the WO 3 can be precipitated by the addition of dilute acid. Tungstic oxide (WO 3 ) is a well-defined compound, and yields a salt corresponding to potassium dichromate. Metallic tungsten can be obtained by the alumino-thermic reduction of tungstic oxide. Both tungstic oxide and sodium tungstate are in demand for various minor industries. Tungstic acid (W 2 O 5 (OH) 2 )isa yellow powder, insoluble in water, which can be obtained in a crystalline condition, and finds use as a mordant ; while sodium tungstate (NagWO^HgO) a colourless crystalline body, made as already described, is soluble in water, and used for fire proofing fabrics and in the preparation of other tungsten compounds. Calcium tungstate is used in connection with plates for radiography for translating X rays into rays of far greater wave-lengths of increased actinic power. TURACINE A nitrogenous, organic, red colouring matter con- tained in the feathers of the African birds named turacos, containing 8 per cent, of copper which is doubtless obtained from the local soil, as it is known to contain malachite. Apart from the copper constituent, the colouring matter would appear to have much the same composition as the colouring matter of blood. TURKEY RED See Madder. TURKEY RED OIL Sulphonated castor oil used in the textile and leather industries. TURMERIC A yellow or saffron colouring matter prepared from the roots of an East Indian plant (Curcuma) ; used for dyeing, also in pharmacy and medicine, and as a constituent of curry powder. TURMERIC PAPER Absorbent paper coloured with a solution of the yellow colouring matter of turmeric, which is turned brown by alkaline solutions, and is sometimes used in place of litmus paper. (See Litmus.) 494 TURNBULL'S BLUE TURPENTINE TURPENTINE Oil or spirits of turpentine is a mixture of the hydrocarbons, known as terpenes, produced by nature in pine-trees, but spruce turpentine is said to consist largely of cymene. The oil is collected by making cuts or slits in the bark of the trees, through which there exudes gum thus, or " crude turpentine," and, when this is distilled with steam, the oil or spirit of turpentine passes over as vapour and is afterwards condensed, leaving rosin behind. There are many kinds of turpentine, meaning the crude products as they exude from the trees, and as many cor- responding oils or spirits of turpentine. American turpentine is obtained chiefly from Pinus australis and Pinus tcsda ; French turpentine from Pinus maritima and Pinus pinaster ; Russian turpentine from Pinus sylvestris and Pinus ledebourii ; German turpentine from the Scotch fir Pinus sylvestvis and Abies pectinata, etc.; Strasburg turpentine from the silver fir, A bies pectinata ; Venice tur- pentine from the larch, Larix Euvopcea ; Indian turpentine from Pinus longifolia Roxb. ; Burma turpentine from Pinus Khassyia (corresponding to the American product); and Chio turpentine from Pistacia terebinthus and Pinus vera. " Pine-cone oil " is obtained by distilling the cones of Abies pectinata with water, and "pine-leaf oil" similarly from the leaves of Pinus sylvestris or Pinus abies. There are also varieties of "pine-needle oils" prepared from' the needles of the various species of pines. The crude turpentine which concretes upon the bark of the trees tapped for turpentine in France is variously called galipot and barras, and is, for the most part, rosin. The turpentines find uses in the crude forms in which they exude from the trees which produce them, but for the most part the oil or spirit is first of all distilled from the crude materials and are then utilized as solvents and as volatile vehicles in connection with many manufactured articles, including paints, varnishes, disinfectants, etc., also in pharmacy and medicine. Turpentine oils, irrespective of source, are colourless mobile fluids each of more or less characteristic odour insoluble in water, but soluble in alcohol, ether, and carbon disulphide, and miscible with many other organic fluids. They vary in specific gravity from 0^865 to o'875, boiling- points from 160 to 162 C., and optical rotatory power, and they differ not only in respect of their origin, but to some T UR PENTINE ULTRA MA RINE 495 TURPENTINE (Continued) extent even among themselves so far as they come from a common source. Turpentine absorbs oxygen when exposed to the air, oxygen, or ozone, and produces a body of the character of a peroxide, which in presence of water gives rise to the formation of hydrogen dioxide, and this property is utilized in the manufacture of " Sanitas fluid," the well-known disinfectant. This absorptive capacity for oxygen is more pronounced in the Indian, Russian, and other sylvestre classes of turpentine. (See also Essential Oils, Balsams, Terpenes, and Rosin.) TURPETH A mineral basic mercuric sulphate (Hg 3 SO 6 or HgS0 4 ,2HgO). TURQUOISE A gem consisting of hydrated aluminium phos- phate coloured by copper and iron. TWITCHELL PROCESS See Fats. TYPE-METAL See Antimony. TYRIAN PURPLE A purple dye chemically associated with indigo, extracted from a species of murex, a mollusc found in the Mediterranean. TYROSINE (CgH^NOg) A crystalline body of silk-like lustre sparingly soluble in cold water, alcohol, and ether, but soluble in boiling water. It is of amino-acid character and is found present in the pancreatic gland, in old cheese, and as a product of putrefactive decomposition of some albu- minous substances, as also of their chemical hydrolysis. It forms a definite additive crystalline hydrochloride (C 9 H U NO 3 ,HC1) with hydrochloric acid, and is one of the organic substances that have been built up synthetically. U-TUBES See Drying Tubes. ULEXITE See Boron. ULTRAMARINE A valuable blue pigment of complicated composition containing aluminium in the form of silicate found in Persia and Turkestan and known as lapis lazuli. It is now made artificially by exposing to a red heat, but below fusing-point (750 to 800 C.), a mixture of kaolin or powdered quartz of high purity, sodium carbonate or caustic soda, sulphur, and charcoal (or pitch or tar), supplemented by some subsequent treatment. Its exact constitution is not known, and it can be made of various tints, green included. Its essential formula has been given as Na 4 (NaS 3 .Al)Al 2 (SiO 4 ) 3 . Another description gives the poor in silica anid rich in sulphur blue type as represented 496 ULTRA MA RINE URA NI UM ULTRAMARINE (Continued) by the formula Na 8 Al 6 SigS 4 O 24 , and the rich in silica and poor in sulphur type as Na 6 Al 4 Si 6 S 4 O 20 . One mixture used for producing a bright blue product consists of 540 kilos kaolin, 8 kilos caustic soda, 538 kilos soda ash, 268 kilos sulphur, and 46 kilos charcoal. It is used in making laundry blues, paints, colours, and paper-manufacture. ULTRA-MICROSCOPE A microscope so constructed that by the aid of very intense and localized light, the intensity of reflection of the substance under examination is greatly increased, thus correspondingly increasing the power of vision. UMBER (Sienna) A pigment used in paint-making, consisting of a natural oxide of iron allied to ochre ; another variety is in the nature of a brown haematite of the composition 2Fe 2 O 3 ,SiO 2 ,H 2 O. The deposits vary in colour^ (from yellow to brown) and in composition. UNSATURATED COMPOUNDS possess unsatisfied affinities, such as phosphine (PH 3 ), in which three only out of the five affinities are saturated by combination with hydrogen, leaving two unsatisfied; again, ethylene (C 2 H 4 ), which may be regarded as only a half-saturated compound. On the other hand, phosphorus pentoxide is a saturated compound. (See Saturated Compounds and Valencies.) UPAS Arrow poison used in the East Indies, obtained from the milky juice of the Upas ant jar and Upas radja. URALITE Hornblende from the Ural districts. URANINE (NajjC^H^Og) -A yellow, crystalline dye, obtained by treating fluorescein with sodium carbonate ; used also for following the course of subterranean waters, etc. URANINITE Pitch-blende. URANITE Uranium minerals, one of which is a phosphate of uranium and copper, and the other a phosphate of uranium and calcium. URANIUM (U) Atomic weight, 238-2 ; sp. gr., 18-68. This metal in the form of an oxide (UO 2 ,2UO 3 ) is contained to the extent of from 40 to 90 per cent, in the mineral pitch- blende which is found in some Cornish mines. It also occurs in uranite, and in a number of other minerals in association with other substances, including carnotite, fev- gusonite, samarskite, etc. It is silver-white in appearance, heavy, melts at a bright red heat (about 800 C.), is soluble in acids, and is made by reduction of the oxides with carbon in the electric furnace. URANIUM URINE 497 URANIUM (Continued) There are an indefinite number of oxides (which are in- soluble in water), the best known being represented by the formula UO 2 , UO 3 , and UO 4 , used in the ceramic indus- tries, and amongst the other better known salts, are uranous sulphate (U(SO 4 ) 2 ), chlorides (UC1 3 , UC1 4 , and UC1 5 ), and the nitrate (UO 2 (NO 3 ) 2 ). The uranous salts are green and the uranic ones yellow in colour, most of which are soluble in water. Some uranium compounds are employed to give a yellow fluorescent colouration to glass, whilst the lower oxide gives a fine black colour. As an element, uranium is the more interesting, as there are reasons for supposing that by some sort of molecular disintegration it gives rise to the production of not only radium and helium, but also some peculiar radium emana- tions (distinct in some respects from radium), and a peculiar form of lead. The radio-active constituent of uranium salts is precipitated from solution by ammonia, but in course of time the radio-activity is recovered. (See Radium and Lead.) UREA or CARBAMIDE (CH 4 N 2 O) A white, crystalline sub- stance known as a constituent of urine, resulting from oxidation of certain nitrogenous bodies in the animal organism. An adult man excretes about 30 grms. daily. It is soluble in water and alcohol and is one of the organic bodies that has been built up synthetically from inorganic materials. Ammonium cyanate is easily transformed into urea (with which it is isomeric), and urea can also be made by the action of ammonia on ethyl carbonate and by the action of mercuric oxide on oxamide. It melts at 132 C. and forms compounds with acids and with bases. (See Cyanic Acid.) URIC ACID (C 5 H 4 N 4 O 3 ) A white crystalline constituent of urine forming the principal part of urinary calculi and deposits, very slightly soluble in water. It is also found in the urine of birds and serpents, and gives rise to a number of derivates, including alloxan (C 4 H 2 N 2 O 4 ), which may be viewed as amides containing the radical C 2 O 2 of oxalic acid. URINE An excretory liquid containing the soluble broken-up or waste products of the living organism. It has an average sp. gr. of 1-02, and amounts to from 1,400 to i, 600 c.c. per twenty-four hours, containing dissolved 3 2 498 URINE VALENCIES URINE (Continued) solid matters to the extent of from 50 to 60 grms., including urea, uric acid, kreatine, kreatinine, smaller amounts of undetermined and varying constituents, and a number of mineral salts. . Kryptophanic Acid (C 6 H 9 NO 6 ) is the normal free acid of human urine, although it has been stated that hippuric acid, which is a normal constituent of the urine of herbi- vorous animals, is sometimes, if not always, present in small quantity in the human liquid excretion. VACUUM A space de voided of air or gas as far as practicable, as, for example, the exhausted glass lamps used for electric lighting. The Thermos flask has a practically vacuous annular space between the two glass vessels of which it is constructed. (See Pumps.) VALENCIES The atoms of elements possess a power of com- bination, or so-called valency, more or less peculiar in char- acter. Hydrogen is a so-called ww^valent element that is, it has only one capability of chemical attachment to another element. Thus, it may be made to combine with chlorine, and the combination may be graphically repre- sented as follows : - - /^^ Cl Hydrogen, then, and the other elements which have a similarly restricted valency are called monads. Oxygen, on the other hand, generally behaves as a ^'valent element, and can combine, for example, with 2 atoms of hydrogen or other monovalent element, as shown by the constitutional formula of water, H 2 O, which may be graphically expressed thus : _0 In other combinations, oxygen behaves as a tetrad as, for example, when it exists in combination with hydrogen as hydrogen dioxide (H 2 O 2 ). VALENCIES 499 VALENCIES (Continued) This represents the view that i atom of oxygen is at- tached, on the one hand, directly to the 2 atoms of hydro- gen, and (as there is reason for thinking) the other atom of oxygen is itself not in direct attachment or combination with the hydrogen atoms. Nitrogen is an example of a tfn'valent element, although in some compounds it behaves as a pentad or pentavalent. For example, in ammonia (NH 3 ) it exists in combination with 3 atoms of hydrogen, and may be represented as follows : whereas, combined as in chloride of ammonium (NH 4 C1), it would appear to exist in pentavalent combination, thus : Carbon is an example of the tetrad class that is to say, it has the power of combining with 4 atoms of hydrogen or 2 atoms of oxygen, as expressed in the two following graphic formulae : (Methane or marsh gas) (Carbon dioxide) (See Saturated and Unsaturated Compounds.) 500 VALERIAN VANADIUM VALERIAN The dried rhizome and roots of Vakriana officinalis containing starch, a resinous substance, the essential oil of valerian, and other substances ; 100 parts of the root yield from about J to ij parts of the oil, which can be obtained by distillation with water. The oil has a sp. gr. of 0*94 to 0-95, and is soluble in alcohol and ether. It is of complicated composition ; yellow-greenish in colour ; has a characteristic strong odour and aromatic taste, and contains some proportion of a terpene (C 10 H 16 ), also some valeric acid (C 5 H 10 O 2 ). The medicinal (carminative) action of the root is really that of the oil. The Japanese valerian oil is known as kesso oil, and has a sp. gr. of 0-996. All the varieties are soluble in alcohol and ether. VALERIC (VALERIANIC) ACID (C 5 H 10 O 2 ) An acid of the fatty series which bears the same relation to amyl alcohol as acetic acid to ethyl alcohol. It is said to exist in four different modifications, the normal variety being a liquid which boils at 185 C., and is soluble in alcohol and ether. One of the varieties is found naturally in many plants, particularly valerian root (see Valerian) and in angelica root from which it is obtained by boiling with soda. Valeric acid is a frequent product of the oxidation of the higher fatty acids, and can be prepared by the oxidation of amyl alcohol. It is used in medicine and perfumery. VALONIA Acorn cups of the Quercus ^gilops, Q. vobuv ) and Q. suber^ rich in tannin ; grown in^ Turkey, Greece, and Roumelia, and used for tanning. VANADITE See Vanadium. VANADIUM (V) Atomic weight, 51*2; sp. gr., 6-025 ; melt- ing-point about 1,730 C. Vanadium is a somewhat rare metallic element which occurs naturally in some minerals, including vanadite (a lead combination), pucherite (a bismuth combination), mottvamite (a lead and copper combination), and patroniU (an impure vanadium sulphide mined in Peru). Vanadium has a commercial importance in connection with the manufacture of certain kinds of steel, to which a very small proportion little more than \ per cent. contributes tensile strength and certain other special properties of much value for some particular applications. It is found present in Bessemer slag at times, being derived from certain iron ores in which it occurs natur- ally in small amount. The metal is soluble in strong acids, and when heated in air burns brilliantly, forming the VANADIUM VAPOUR DENSITIES 501 VANADIUM (Continued) pentoxide (V 2 O 5 ). It is said to form five oxides corre- sponding to the oxides of nitrogen ; it also forms a nitride with nitrogen, three chlorides (VC1 2 , VC1 3 , and VC1 4 ) and acts as a feeble base. The tetrachloride, which is dark green and soluble in water, is used as a mordant in the textile industry ; the oxides are insoluble in water and are used in metallurgy ; and two sulphates (green and blue salts, soluble in water) are also used as mordants. VANILLA The pods of Vanilla planifolia, an orchid which grows wild in Mexico, Brazil, and Guiana, and is cultivated in many tropical countries, contain shining crystals of vanillin (C 8 H 8 O 3 ) in association with other constituents, and have a pleasant aromatic taste and odour. Vanilla is used largely for flavouring purposes and in medicine. The odoriferous principle (vanillin) is prepared on a large scale from coniferin (C 16 H 22 O 8 + 2H 2 O), a com- pound present in the sap of the cambium in the conifers. This by hydrolysis yields glucose and coniferyl alcohol, and the latter by oxidation gives vanillin. It can also be obtained by the oxidation of eugenol, ozone being one of the agents employed. Vanillin is soluble in water, alcohol, and ether, and melts at 80 C. VAPOUR DENSITIES The relative weights of gases at the same temperature and pressure compared with hydrogen as the unit, determined either by ascertaining the weight of a given volume or the volume of a given weight of vapour. These densities or specific gravities of the elements are in some cases identical with their atomic weights, including hydrogen, oxygen, nitrogen, chlorine, bromine, iodine, sulphur and selenium. The exceptions to the rule include mercury, cadmium, zinc, potassium, sodium, arsenic and phosphorus, the first five named of which have densities one- half of their atomic weights, and the last two twice that of their atomic weights. The general law is that the vapour densities of the elements are one-half of their molecular weights, and the explanation of the noted exceptions lies in the fact that the molecules of mercury, cadmium, zinc, potassium and sodium, consist of but one atom, so that their atomic and molecular weights are identical, while arsenic and phos- phorus contain each four atoms in their molecules, and their smallest part that can take part in a chemical change is one-fourth of their molecular weights or one-half of their densities. (See Gases, Molecules, and Valencies.) 502 VAREC VEGETABLE OIL SEEDS VAREC The Normandy name for the ashes of seaweeds, (See Barilla and Vriac.) VARNISHES are solutions of resinous substances which, when spread over the surface of any object, leave behind, after evaporation of the volatile vehicle, a thin shiny layer of the dissolved bodies. Varnishes are used as protective coverings to painted wooden, iron, and other surfaces. Copal, shellac, dammar, sandarach, mastic, elimi, benzoin, anime, resin, asphalt, etc., are all used in compounding them according to the purpose of their applications, copal varnish being one of the most important. To dissolve copal and some of the other gums, it is requisite to powder and subject them to a process of dry distillation at a temperature of about 360 C., by which treatment they lose from 20 to 25 per cent, of their weight. They can then be dissolved in turpentine and boiled linseed oil. While these two liquids are used in compounding ordinary varnishes, others are made using spirits of wine, or petrol, or turpen- tine, or other solvent alone. Driers are chemical materials used in varnish and paint making to facilitate the drying process. For varnish-making, manganese dioxide, manganese resinate, manganese borate, and litharge (lead oxide) are used ; while for paints, apart from the drying properties of any lead oxides that may be incorporated, and that of the varnish itself (when incorpor- ated in the paints), the drying depends mainly upon the boiled linseed oil used in compounding them. (See Ester Gums and Paints.) VASELINE A solid, jelly-like substance composed almost entirely of highly saturated hydrocarbons, obtained as a residual from the distillation of petroleum, and subse- quently purified from associated bodies. It is used in compounding ointments, in preparation of polishes, as a lubricant, and in leather-dressing, etc. (See Petroleum.) VEGETABLE BLACKS Carbon from various sources used as pigments. (See Bone Black, Ivory Black, and Lamp Black.) VEGETABLE IVORY The tagua-nut of the Phytelephas macro- carpa tree which grows in Columbia (South America). It has the appearance of ivory and is very hard, but can be turned in the lathe. VEGETABLE OIL SEEDS The cakes left from the extraction of oils from such materials as copra, cotton- seed, ground- nuts, linseed, palm- kernels, rape-seed, rice bran, rice meal, sesame-seed, soya-beans, etc., are employed as cattle foods. (See Oil Cake.) VEGETABLE TALLOW VEGETO-ALKALOIDS 503 VEGETABLE TALLOW (Chinese), obtained from the seeds of Stillingia sebifera and used in candle-making, is produced of two qualities, "prima" and "secunda," having sp. grs. of 0-8843 t 0*904 and 0*8928 respectively, and saponifica- tion values of 206 and 204. The "prima" quality melts at 36 to 47 C. and its iodine value is 19*37 to 60*76, whilst the "secunda" iodine value is 82*20. VEGETABLE WAX (Japan Wax) See Waxes. VEGETATION The chemical processes involved in vegetable life are only comparable to those concerning the animal organism, and are of the same general order. Fed upon water, the atmospheric constituents, and the matters present in soil, the list of vegetable products is wide and wonderful. In addition to the cellulosic compounds constituting the cells and vessels, there are the wide range of colouring matters (see Plant Colouring Matters), the various alka- loidal bodies, such as aconitine, quinine, and morphine, a range of carbohydrates, including starches and sugars, a still wider range of essential oils and other volatile principles, and innumerable chemical products having medicinal or commercial value, all of which are built up synthetically by the agency (life-action) of the nitrogenous protoplasm. Vegetation has an important bearing upon the health of communities as, apart from the capacity of plant life for absorbing carbon dioxide from the air and restoring oxygen thereto (see Carbon and Air), trees absorb from the soil a great deal of water, which for the most part is subsequently evaporated into the air from the surfaces of the leaves, so that many malarious districts can be made drier and more healthy by means of plantations. Again, many plants and trees give off essential oils into the air and thus exercise a beneficial effect due to their balsamic character and the subsequent production of hydrogen dioxide by the action of the air and moisture upon these oils. Vegetation also assists in the purification of polluted waters and soils by utilizing their organic constituents. As a rule, plants obtain what nitrogen they require from the ammonia and other soluble nitrogen compounds that are present in the air and soil, the ammonia for the most part coming from products of organic decay; but some plants of the leguminous order, such as peas and beans, as- similate nitrogen direct from the air by some action of bacteria situate in nodules which form on the rootlets of these plants. (See Bacteria, Carbon, Fertilizers, and Soils.) VEGETO-ALKALOIDS See Alkaloids, 504 VENETIAN REDVETIVER OIL VENETIAN RED A pigment and polishing-powder, consisting of ferric oxide, made from red haematite or by calcining ferrous sulphate. VENICE TURPENTINE See Turpentine. VENTZKE DEGREES are referable to a determination of the sucrose or cane-sugar content of a solution by means of a polariscope, the scale being so graduated that the amount is read off direct. When the normal weight of 26-048 grms. of sucrose are dissolved in 100 c.c. of solution in a 200 mm. tube, the degree registered is 100 and so on. VERATRINE This is really a mixture of alkaloids obtained from sabadilla (cevadilla) the dried ripe powdered seeds of Schoenocaulon officinale by exhausting with alcohol. The chief alkaloid is cevadine (C 32 H 49 NO 9 ), also termed vera- trine, and it is accompanied with veratridine (C 37 H 53 NO n ). Cevadine is a white, crystalline body of extremely poisonous character, soluble in alcohol and ether, and is used medicin- ally as an anti- febrile agent. (See Sabadilla.) VERBENA OIL (sp. gr., 0-894 to 0-918 ; rotation, - 12 to - 16) is distilled from the leaves of Verbena tryphilla, grown in France and Spain, and contains from 21 to 38 per cent, of citral. The Indian oil (lemon grass) comes from the grasses Andropogon citratus (Ceylon and Straits Settlements) and A.flemosus (Malabar and Cochin), its chief constituent being citrol. Its sp. gr. is 0-877 to '95 5 rotation, + 3 to - 3 ; and it contains from 75 to 85 per cent, citral. VERDIGRIS A poisonous, green-coloured basic carbonate (CuCO 3 ,Cu(HO) 2 ) which forms on copper when exposed to damp air. VERMILION See Mercury (Sulphide). VERMILION SUBSTITUTE A preparation which has largely supplanted mercuric sulphide, consisting of about 95 per cent. Pb 3 O 4 coloured with eosin (tetrabromo-fluorescin) a red, crystalline, organic dye. VERONAL See Barbitone. VESUVIAN (Vesuvianite) A crystalline mineral consisting in the main of calcium-aluminium silicate. VETIVER OIL (discus Oil), distilled from the roots of Andro- pogon muricatus and used in perfumery, is a thick yellow oil of 'an odour like that of violets, soluble in alcohol, ether, etc./ and of sp. gr. about I -o. VI 'N EG A R VITA MINES 505 VINEGAR is a preparation of acetic acid, of which it contains a legal minimum of 4 per cent. The ordinary English variety is made by the method referred to under Acetic Acid, the British production being estimated at 15 million gallons per annum. In Germany and France, it is made from wine by exposure to the air in casks containing some beech- shavings or by mere exposure to the air in sunlight. Malt Vinegar is prepared from malt or malt and raw barley mashed as in brewing and then submitted to vinous fermentation and subsequently soured as already described. Distilled Vinegar is any variety of vinegar submitted to distillation, so that it is thereby deprived of its colouring matter. Tomato Vinegar is simply vinegar flavoured with an infusion of tomatoes, or tomatoes may be added to the alcohol or wine before acetification. VIOLET ESSENCE See Orris Oil. VISCOID See Silk, Artificial. VISCOSE See Silk, Artificial. VISCOSIMETER An instrument or apparatus for determining viscosity. VISCOSITY The viscosity of a colloid solution is ascertained by measuring the time of outflow from a standard volu- metric pipette; roughly expressed, the viscosity is in- versely proportional to that time. The viscosity of oils and greases is determined in much the same way, or by the time taken, under standardized conditions, for a metallic bulb to fall through a measured column of the substance under examination. VISCOUS Thick, sticky, glutinous, ropy. VITAMINES (Accessory Food Factors) The name given to some mysterious soluble substances of nitrogenous nature present in certain living tissues and products, including butter and cod-liver oil, but absent from lard and nut and seed oils after they have been hydrogenized. In butter they are contained in the less crystallizable part known as butter oil. One class (A) is soluble in fat solvents, a second class (B) is soluble in water but not in fat solvents, and a third class (C) is soluble both in water and alcohol. They are supposed to have great influence in the promotion of growth, as although they exist in very small amounts, they exercise an influence like that of enzymes in converting what would otherwise be non-efficient dietaries into efficient ones . 5o6 VITAMINES-" VITREOSIL " VITAMINES (Continued) It has been stated that the fresh juices of the edible parts of the orange, lemon, and grape-fruit contain water- soluble so-called B-vitamine equivalent, volume for volume, with cow's milk, grape-juice being inferior in this respect ; and that the edible parts of apples and pears furnish some quantity, but are not rich in this respect, while prunes are somewhat richer. Further, that lard, palm, yellow maize, and cotton-seed oils apparently contain appreciable amounts of the fat-soluble, growth-promoting substance, and that cabbages and potatoes both contain the fat-soluble factor, which can be extracted by alcohol, raw cabbages being particularly rich. Crude unrefined cod-liver oil is said to be 250 times as potent as butter, whilst swedes are very rich in the antiscorbutic vitamine (C). In the absence of the fat-soluble vitamine (A) normal nutrition is deficient. The disease known as beri-beri, which is endemic in Japan, the Malay Peninsula, and the Dutch Indies, has been attributed to the habit of feeding too exclusively upon polished rice, due to the removal of the constituent water- soluble B-vitamine which is associated with the " silver skin " of the seed, and which is unfortunately removed by the milling process now prevalent for polishing the rice. Similarly, soldiers or sailors who for long periods are unable to obtain supplies of fresh foods are liable to scurvy, and probably for a similar reason, as this disease can be prevented by the use of fresh meat and vegetables and of orange and lemon juices, all of which contain the vitamines of class C. The antiscorbutic vitamine is stated to be very sensitive to alkaline reaction, and is completely destroyed by heat, unless associated with an acid which greatly protects it in this respect, so that the tomato, for instance, is antiscorbutic even after canning. Diets may be perfectly wholesome and perfectly digested, but unless the food is associated with a proper proportion, small as it is, of vitamines derived from living cells of plants or animals, the nutrition, particularly of the nervous system, is defective. Egg-yolk, milk, butter, cabbages, potatoes, edible pulses, spinach, yeast, and the germs and cells of cereals are all good vitamine-carrying foods when fresh. (See Foods and Hormones.) "VITREOSIL" A trade proprietary name for pure fused silica used in making laboratory ware heat and acid proof, and of opaque, translucent, and transparent qualities. VITREOUS" VOLTOL" OILS J 507 VITREOUS Glassy. VITRIOL or OIL OF VITRIOL Strong sulphuric acid (See p. 468.) VIVIANITE A mineral ferrous phosphate. VOLATILE Light, ethereal, easily passing from the liquid to the gaseous state VOLTAMETER An apparatus for the electrolysis of water that is, its decomposition by means of an electric current. A simple form (as illustrated) consists of an inverted funnel-head, the neck of which is closed with a cork or com- position through which are passed two platinum wires terminating above in small plates of the same metal. The funnel is partly filled with water, and over the upright platinum plates, two test-tubes filled with water acidu- lated with a little sulphuric acid (to assist the passage of the electric cur- rent) are inverted. On connecting the wires with a battery of three or four cells the current passes, and by de- composition of the water causes the production of 2 volumes (parts) of hydrogen gas in the one tube and i volume (part) of oxygen gas in the other. (See also Eudiometer.) " VOLTOL " OILS Oils such as rape and marine animal oils, thickened by blowing, followed by electrical treatment (the high viscosity thus secured being due to oxidation and polymerization), and used amongst other applications for ad- mixture with mineral oils to be used as lubricants, in the place of castor oil. The following information is taken from a recent article in the Chemical Age (December n, 1920) : A Voltameter. Sp.Gr. Refractive Index at 15 C. Viscosity at 100 C. Acid Number. Iodine Number. Mean Molecular Weight. Rape voltol Whale voltol ... 0-9740 0*9819 I-485 IHSS 83-6 74'9 II'7 i5'4 52 51 I20O 1000 5o8 "VOLTOL" OILS VOLUMETRIC ANALYSES "VOLTOL" OILS (Continued) The high viscosity of voltol oils is due in part to the con- tained oxidation products and polymerization induced by the blowing, but chiefly to the production of di-molecular glycerides under the influence of the electric discharge, thus accounting for the high molecular weights. VOLUMETRIC ANALYSES Methods of determining the amounts of chemical substances present in solutions, by the employment of reagents of definite strength in connec- tion with well-understood interactions. To determine, for example, the amount of free iodine contained in an acidified solution of potassium iodide, a standardized solution of sodium hyposulphite is employed that is to say, a solution of predetermined strength and this is gradually run into the subject mixture, from a burette until the colour has entirely disappeared. It is then easy to calculate from the known chemical interaction that takes place the amount of free iodine in the mixture. The inter- action is represented as follows : I 2 + 2Na 2 S 2 O 3 = 2NaI + Na 2 S 4 O 6 that is to say, the free iodine is converted into potassium iodide and the sodium hyposulphite into sodium tetrathion- ate, and knowing the amount of hyposulphite consumed it is easy to calculate the amount of free iodine changed as explained. If a little starch solution be added to the iodine solution just before the completion of the titration, a beautiful blue colouration is produced, and this is generally done in practice as it is so much more evident than that of the uncombined iodine colouration. For the determination of the amount of alkali or acid present in solutions, calculations are made based upon the amount of standardized solutions of acid or alkali required respectively by titration to neutralize them, this point of neutrality being ascertained by means of an indicator, or substance which undergoes a marked change of colour upon the change from alkalinity to acidity or vice versa. The indicators chiefly used are methyl orange, phenol- phthalein, and litmus. Others are aurin, cochineal, cur- cumin (turmeric yellow), gallein (alizarin violet), iodoesin (prepared by iodating fluorescein), lacmoid (resorcin blue), and methyl red. Methyl orange, lacmoid, cochineal, and iodoesin are in- sensitive to weak acids ; litmus is typical of the indicators VOLUMETRIC ANALYSES WALNUT OIL 509 VOLUMETRIC ANALYSES (Continued} somewhat sensitive to weak acids ; and phenolphthalein, turmeric, and rosolic acid are highly sensitive to weak acids. Methyl orange dissolved in water is turned yellow by alkalies and pink-red by acids. Phenolphthalein dissolved in alcohol is colourless, but alkalies turn it to a deep red colour, which is at once discharged by acids. In the precipitation of anthranilic acid (amino-benzoic acid) from its alkaline solution by addition of mineral acid, an acid reaction to methyl red indicates the approach of the end-point, a further addition of acid indicating the point of maximum precipitation is shown by the acid reaction to thymol blue. Thymolsulphophthalein is said to be a useful indicator in the liming of sulphonation mixtures, a red colouration indicating that free acid is still present. When the in- dicator shows a yellow colour the end-point is near, and a blue colour shows that the mixture is alkaline, Dibromocresolsulphophthalein or dibromothymolsulpho- phthalein may be used as substitutes for litmus, the former changing from yellow to purple and the latter from yellow to blue. Other volumetric methods are based upon processes of oxidation, reduction, and precipitation. (See also Burette, Litmus, Reagents, and Turmeric Paper.) VRIAC A French term for kelp. VULCANITE is made by heating 2 parts of india-rubber with i part of sulphur to a temperature of about 150 C., and is largely used for making pumps, taps, tubing, and unions for use in chemical works, as also for combs and other articles. Gutta-percha is vulcanized in the same way. (See Rubber.) VULCANIZATION See Rubber. WALNUT OIL, expressed from the seeds of Juglans regia, is of pale yellowish-green colour, with sp. gr. 0-92 to 0-93 ; refrac- tive index, 1-4808; saponification value, 192 to 197; and iodine value, 142 to 146. The main constituent is linolic acid. It is soluble in alcohol and ether and is used in the varnish and paint trades. 5io WA SH-BOTTLE WA TER WASH-BOTTLE A flask fitted with a cork or rubber stopper having two borings, through which pass bent tubes : a short one terminating just below the stopper, while the other goes nearly to the bottom of the flask and terminates at the outside end in a drawn-out point, so that when in use (as, for instance, washing a pre- cipitate upon a filter) the water emerges there- from in a fine stream. By applying the mouth to the short tube and blowing, the water is forced out of the flask through the longer tube. In other cases, wash- bottles, instead of being filled with water, are charged with alcohol, ether, or other solvent, according to the solubilities of the substances to be removed from the subject-matter of the washing. Appliances similarly constructed, using either flasks or bottles, are also used for washing gases, the gas being passed or drawn through the liquid contents by the long tube, and the washed gas escaping through the shorter tube. (See Aspirator.) WASHING SODA- See Sodium Carbonate, p. 443. WATER (H 2 O) Molecular weight, 18. Water is known to all, in the various forms of rain, snow, ice, and steam ; but, unlike the air we breathe (which, it will be remembered, is a mechanical mixture), water is a real chemical compound and consists or is made up of the two elements, hydrogen and oxygen. Hydrogen and oxygen in their ordinary state are both gases; but when they are made to combine as, for example, by the agency of electricity they form water. Two parts of hydrogen (H) by volume combine with i part or volume of oxygen (O) and make water, which chemists symbolize with the lettering H 2 O, which shows that water is composed or made up of 2 atoms hydrogen and i atom oxygen. Water boils at 100 C. (212 F.) and freezes at o C. (32 F.) to a crystalline solid having a sp. gr. of 0-93. It attains its maximum density at 4 C. (See footnote, p. 240.) In its several forms, water makes up about three-quarters of the materials constituting the surface of the earth. It also enters largely into the composition of the tissues of vegetables and animals to the extent of from 80 to 90 per cent. WATER 511 WATER (Continued} It has greater solvent power than any other liquid in respect of variety of substances, and enters largely into the composition (constitution) of many chemical substances, such as hydrates and salts, being combined in the last- named substances as water of crystallization. Copper sulphate, for example, crystallizes in a form containing 5 molecules of water (CuSO 4 ,5H 2 O) and magnesium sulphate with 7 molecules (MgSO 4 ,7H 2 O). Sodium chloride is known in two crystalline forms viz., NaCl,2H 2 O and NaCl,ioH 2 O: whilst sodium carbonate is known in chemical association with water in several forms, including Na 2 CO 3 ,ioH 2 O, Na 2 CO 3 ,7H 2 O, and Na 2 CO 3 , H 2 O, and so forth. In many cases, the colours of salts are dependent upon the amount of water of crystallization, as instanced by cobalt chloride (CoCl 2 ,6H 2 O), which is pink, but when gently heated to 120 C. becomes blue in colour by the loss of its water hence the employment of the pink compound in the preparation of so-called sympathetic inks, the faintly pink written words becoming visibly blue upon warming of the paper on which they are written. Another compound viz., magnesium platino-cyanide in its crystalline form contains 7 molecules of water (MgPt(CN) 4 ,7H 2 O) and is of a bright scarlet colour, but when heated to 50 C. it loses 2 molecules of water and be- comes MgPt(CN ) 4 ,5H 2 O, which is of a canary-yellow colour, and upon raising the temperature to 100 C. a white salt finally results, having the composition MgPt(CN) 4 ,2H 2 O. (See also Efflorescence and Deliquescence.) Sea water is impregnated with salts washed out of the earth's surface ; has a sp. gr. of about 1*025 to 1-027, as compared with ordinary water, i-o; and contains large quantities of common salt and magnesium chloride. The water of the British Channel contains 28-05 parts NaCl, 3-66 parts of MgCl 2 , and 47 parts of other mineral sub- stances in each 1,000 parts. Rain-water, as collected in country places where the air is not fouled with smoke and other emanations, is as nearly pure as it can be found in nature, but even then it contains about 2j volumes of air dissolved in each 100 volumes by measure. Water as given off from the lungs in respired air by adults in twenty-four hours has been estimated at an average of 311 grms., or nearly n ounces. When water is boiled it takes the form of steam, which 512 WATER WATER GAS WATER (Continued) is its gaseous state, and when this is again cooled, it becomes condensed as water once more, and is known as distilled water. Steam is an effective germ destroyer, and there are a number of so-called disinfectors or destroyers in which it is generated and used for the disinfection of clothing and bedding. Rain water is a sort of distilled water. The heat of the sun evaporates water from the earth and the sea, and then, when the air is more or less saturated with the water vapour and becomes cold enough, it is transformed and falls as rain, or snow, or hail. Water, as ordinarily supplied for drinking purposes, contains impurities in the form of substances dissolved out of the earth with which it comes naturally into contact, and supplies are roughly classified as "hard" or " soft" in character. The so-called " temporary hardness " is mainly derived from the presence of calcium carbonate or chalk in solution, which is deposited as a fur or cake in tea-kettles and boilers. This deposition is due to the expulsion of carbon dioxide, also contained in the water, and which by its presence, and until expelled by the heat, holds the chalk in solution. Such waters may be softened to some extent by boiling, or by the addition of lime, which, by entering into combination with the carbon dioxide, forms insoluble calcium carbonate (CaO + CO 2 =CaCO 3 ), which is deposited along with the carbonate previously held in solution by the carbon dioxide thus removed. The " permanent hardness " of natural waters is largely due to the presence in solution of the sulphates of calcium and magnesium, the degree of hardness being dependent upon the nature of the geological formation in which the water is found. The " Permutit " system of water-softening is referred to under that heading. Many gases are soluble in water to some extent, including nitrogen, oxygen, carbon dioxide, and argon, the degree varying with the temperature, etc. Soft water is water which is more or less devoid of sub- stances held in solution, so that freshly collected rain water is quite soft in character. (See also Filters.) WATER GAS is obtained by passing steam over red-hot coke, which has the effect of decomposing the water- vapour and producing a mixture of hydrogen and carbon monoxide gases WATER GAS WAXES 513 WATER GAS (Continued) To make this mixture of gases (which otherwise burns without flame when lighted) luminous when burning, it is mixed with oil vapours, and it is also employed for mixing with ordinary coal gas. (See Coal Gas and Producer Gas.) WATER-GLASS See Silica, p. 431. WATER-OVEN An appliance, as illustrated in the figure, in which it is possible to dry chemical sub- stances (in suitable containers) at 100 C., consisting of a water- jacketed copper box which can be heated by a lamp placed below. A vent is provided for the escaping steam and for charging the jacket with water, and through the other opening on the top, a thermometer fitted with a cork may be placed. The figure shows such an oven connected with a con- denser for the escaping steam, which may be thus made to furnish a supply of distilled water. WATTLE Bark from the Australian wattles Acacia pycnantha, A. mollissima, and A. binervata, used in tanning. (See Tannins.) WAVELLITE A native aluminium phosphate (2A1 2 (PO 4 ) 2 , A1 2 (HO) 6 ,9H 2 0). WAXES There are many waxes of mineral, animal, and veget- able origin, of which the best-known variety is Beeswax, produced by bees from the sugar of their food. It is some- what yellow, tough and solid, and can be bleached by chlorine. It is of complex composition, and contains several different substances including myricin (myricyl palmitate, or the melissic ester of palmitic acid, C 46 H 9 ,O 2 ) and free cerotic acid (C2 6 H 62 O 2 ) one of the normal fatty acids. It melts at 63 C. ; its sp. gr. is 0-96 to 0*97 ; it is soluble in alcohol, ether, and chloroform, and is used in making candles and various polishes. 33 514 WAXES WAXES (Continued) Bay-berry Wax, from the bark of the Myrica ( Candle- berry, Bay-berry, Wax-berry), is green in colour, and con- sists of palmitin, palmitic acid, myristin, and lauric acid. It is used in candle-making. Candelilla Wax is- found as an excretion on Euphorbia cerifera and E. antisyphilitica (plants growing in North Mexico and southern parts of the United States), from which it is obtained by boiling them in water and adding some sulphuric acid. It is used in making polishes, candles, sealing wax, etc. It is opaque to translucent, melts at about 67 C., has a sp. gr. of 0-983, and an iodine value of 37. Carnauba Wax is obtained from the leaves of a palm (Copernica cerifera) in Brazil, they being coated with this yellowish -white exudation, which melts at 84 to 86 C., and in many respects resembles beeswax, for which it is used for some purposes as a substitute. Its sp. gr. is 0-995, and it is soluble in alcohol and hot ether. Ceresine is a white wax-like substance of mineral character obtained by purification of ozokerite, consisting of treatment with strong sulphuric acid, followed by filtration in a melted condition through animal charcoal. It is used in candle- making and as a substitute for, or admixture with, bees- wax ; has a sp. gr. of 0-92 to 0-94, melts at 74 to 80 C., and is soluble in alcohol, benzol, etc. Chinese Wax (Pela), or vegetable insect wax, is formed on the branches of a species of ash-tree (Fraxinus chinesis) by the puncture of the coccus insect (Coccus ceriferus). It resembles spermaceti ; consists for the most part of a sub- stance named cerobylic or ceryl cerotate, and is used in China for candle-making. It admits, like the fats, of saponification with potash ; is white to yellowish in colour, of sp. gr. of 0-970, melts at 80 to 83 C., and is soluble in alcohol, benzol, and chloroform. Coca Wax (C 33 H 66 O 2 ) is obtained from the leaves of the Ery thro xy Ion coca plant cultivated in Peru, Bolivia, and Brazil, and which are used for chewing like tobacco (see also Cocaine). After purification, it is a white amorphous substance which melts at 70 C. and is readily soluble in hot alcohol. Cotton-Seed Wax Contained in raw cotton to the extent of about 0-5 per cent. WAXES 515 WAXES (Continued) Cow-Tree Wax is obtained by evaporating the milk of the cow-tree (Palo de vaca, Brosunum galactodendron). It resembles beeswax in some general characters and admits of saponi- fication. Godang Wax (Getah Wax) is made from the latex of a wild fig-tree (Ficus cevuflua or F.- subracemosa). Japan or Vegetable Wax, or tree wax, is partly obtained in the East Indies from berries of the Rhu$ succedanea and several species of sumach-tree by boiling the fruit in water. It is not a real wax but a glyceride, and con- tains palmitin with free palmitic acid. It has a yellow colour, is soluble in benzol and naphtha, melts at 53 C., and is of sp. gr. 0*970 to 0*980. The Island of Kyushu accounts for about one-half of the total production obtained from the fruit kernels of a tree peculiar to Japan. It is used in making wax matches, candles, furniture polish, and leather-dressing. Montan Wax is extracted from pyropissite obtained from the lignites of Saxony and Thuringia. When refined it is white, and is used as a substitute for carnauba wax. It is soluble in benzol, chloroform, and carbon tetrachloride. Ocuba Wax is obtained from the fruit of Myristica ocuba officinalis, which grows in marshy ground on the Amazon shores, and is used in Brazil for making candles. Paraffin Wax is made from ozokerite by treatment with sulphuric acid and subsequent bleaching, and is also a solid constituent of the oily distillates from natural bitu- minous substances, including coal, shale, lignite, peat, wood, and natural petroleum, from which it is obtained by re- frigeration. It is a white translucent mixture of hydro- carbons of sp. gr. 0-880 to 0-915, and melts between 45 and 65 C. It is soluble in turpentine, benzol, carbon disulphide, and chloroform, and comes into the market in many grades, some hard and some soft, all known as " paraffin scale" before purification, and is extensively used in the manufacture of candles, floor polishes, waxed paper, lubri- cants, waterproofing of wood and cprks, etc. By oxidation at 150 C. in a stream of oxygen and in presence of manganese compounds it is by catalytic action largely resolved into fatty acids, the resulting mass con- taining 35 per cent, insoluble in water, and about 25 per cent, of lower fatty acids (up to C 10 ). 516 WAXES WAXES (Continued) Palm Wax comes from the Ceroxylon andicola, a palm indigenous in the tropical parts of America, on the stem of which it forms a covering. In Ecuador, trees are found in great numbers, each of which furnishes about 50 Ibs. of wax. After washing with hot water, in which it does not melt, it is mixed with a little tallow and made into balls for exportation. It is yellow, and really consists of a wax and resin which are separated by hot alcohol, the resin remaining in solution and the wax separating out as a jelly on cooling. When purified in this way it resembles bees- wax in appearance and composition. Pisang Wax, a powdery mass obtained from the leaves of the Cera miisa, indigenous in Java. Raphia Wax is found as a whitish layer on the under sides of the leaves of a Madagascar palm. The dried leaves yield about 10 per cent. Its sp. gr. is 0-834, melt- ing-point 82-5 C., saponification value 51, and iodine value from 7-7 to 10-7. Spermaceti, an ester (cetyl palmitate, C le H 33 O.CO.C 15 H 31 or C 32 H 64 O 2 ). It is a pearly white, fatty substance found in certain cavities of the head of the sperm whale (Physetev macYocephalns) and in smaller quantity in the blubber of the Balana ro strata. It is soluble in carbon disulphide and ether, is apt to become rancid when exposed to light, has a sp. gr. of 0-929, melts at from 44 to 47*5 C., and is associated with sperm oil, from which it has to be freed before it attains the scaly, brittle, soft character of the commercial article. Amongst other applications it is used in the manufacture of candles, soaps, and ointments. Sugar- Cane Wax, a by-product in the sugar manufacture, obtained from the canes particularly the violet species by scraping or skimming off the juice resulting from boiling them out. It is hard, yellow, granular, soluble in hot alcohol and benzene, melts at 82 C., and has a sp. gr. of 0-961. It appears to contain 45 per cent, of myricil alcohol (C 30 H 62 O) and another substance (C 33 H 68 O) asso- ciated with palmitic and stearic acids. It is extracted in Java. Wool Wax appears to be refined wool grease. Its sp. gr. is 0*94, it melts at 35 C., saponification value 102, iodine value 25, and refractive index 1-48. (See Suint.) WAXES WEIGHTS AND MEASURES 517 WAXES (Continued) APPROXIMATE TYPICAL VALUES OR CONSTANTS. Name. Specific Gravity. Melting- Point. Iodine Value. Saponi fication Number. Beeswax 0-965-0-97 63-64 C. 9 95 Candelilla ... 0*94-0-983 67-68 C. 37 46-65 Carnauba Q'995 84-86 C. 13 80 Ceresine 0-92-0-94 74-8o C. Chinese 0-97 8o-83 C. i '4 80-93 Coca 70 C. Japan Montan 0-970-0-980 53 C. 72-77 C. 6 220 Myrtle 0-99 o P i '95 208 Ocuba 0-92 39*4 Paraffin o'88-o'O9i5 45-65 C. Spermaceti . . . 0-945-0-96 43-47 C. 3'5-4'o 122-130 Sugar-Cane ... 0-968 55 C. 60 1 68 WEIGHT The force by which the mass of a substance is attracted by gravity, varying therefore according to the altitude where the weight is determined. WEIGHTS See Scales and Weights and Measures. WEIGHTS AND MEASURES The weights and measures used for the most part by chemists are those of the decimal or metric system, and the chief factors and their English equivalents are as follows : Capacity : i litre =1,000 cubic centimetres = 35 J English ounces or 1-76077 pints; and there are about 4^ litres to the English gallon. i cubic centimetre (i c.c.) is equal to 15*43 grains of water at 4 C., and is the standard of the French or metric system of weights and measures, i gallon = 70,000 grains = 10 Ibs. avoirdupois weight of water and 4*5366 litres. Weight : i gramme (or gram) is the weight of i cubic centi- metre (i c.c.) of water at 4 C. i milligram is the i.oooth part of a gramme, i centigram is the looth part of a gramme. 518 WEIGHTS AND MEASURES WEIGHTS AND MEASURES (Continued) i decigram is the loth part of a gramme. 1,000 grammes = i kilogramme. i English Ib. = 454*43 grammes, and i oz. = 28*35 grammes. i gramme = 15*43235 English grains. i Ib. = 7,000 grains, i gallon of water = 10 Ibs. i cubic foot of water = 62*321 Ibs. Length : The abbreviation mm. stands for millimetre, or the i,oooth part of a metre. 25 mm. = i inch. i metre =39*37 English inches. i kilometre = 1,000 metres or about 1,100 English yards. i decimetre = the loth part of a metre, i centimetre = the looth part of a metre, i millimetre = the i,oooth part of a metre. Avoirdupois Weights : 1 6 drams = i oz. 1 6 ozs. = i Ib. 112 Ibs. = i cwt. 20 cwts. = i ton. Apothecaries' Weights : 20 grains = i scruple ( B). 3 scruples = i drachm (3). 8 drachms ^ i ounce (). 12 ounces = i Ib. British Pharmacopoeia (Capacities) : i minim = i drop (n\). 60 minims = i fluid drachm (fl. drm.) (3), (i tea- spoonful). 8 fluid drachms = i fluid ounce (fl. oz.) (g), (2 table- spoonfuls). 20 fluid ounces = i pint (O.) 8 pints = i gallon (C.) Other Useful Data : To reduce kilogrammes to Ibs. multiply by 2*2046. To reduce litres to gallons 0*22. To reduce grammes to grains i5*43 2 - To reduce grains to grammes ,, ,, 0*0648. To reduce ounces to grammes 28*349. i inch = 2*539954 centimetres, i foot = 3*0479449 decimetres, i yard = 0*91438348 metre, i mile= 1*6093149 kilometres. WEIGHTS AND MEASURES WINE 519 WEIGHTS AND MEASURES (Continued) The factor for the conversion of the American gallon into the British is 0-834. " WELDON PROCESS " is one for the recovery of the manganese from the manganous chloride resulting from the manu- facture of chlorine (see p." 109), in the form of manganese dioxide or its equivalent, for use over again. The liquor is treated with an excess of milk of lime and air blown through the mixture, and in this way, the manganese hydroxide is converted mainly into a combination of man- ganese dioxide with calcium oxide, forming the Weldon mud. WELSBACH LIGHT See Light, p. 292. WHALE OIL See Fish Oils. WHATMAN EXTRACTION THIMBLES See Filters WHISKY Spirit distilled from the fermented wort prepared from malted barley dried over a peat fire ; in other words, " a spirit distilled from a mash of cereal grains saccharified by the diastase of malt." WHITE ARSENIC Arsenious oxide, (See Arsenic.) WHITE-DAMP See Coal. WHITE-LEAD See Lead. WHITE VITRIOL A commercial name for zinc sulphate. WHITING A purified preparation of chalk. WILLESDEN PAPER See Cellulose and Copper, p. 137. WINE The fermented juice of grapes (of which there are some 600 varieties), the colour of which depends upon that of their husks if and when they are included in the making. Red grapes can be made to give yellow or white wines if the husks be excluded, as in the cases of sherry and champagne. The flavour and other characters of wines depend not only upon the kind of grapes from which they are made but also upon the soil on which they are grown, and upon the ethereal bodies resulting from changes that take place upon keeping. Dry wines contain little or no sugar ; sweet wines contain sugar in greater or less pro- portion ; while effervescent wines like sparkling Moselle and Champagne contain sugar in a state of fermentation, or are effervescent as the result of fermentation that takes place after bottling. They all contain alcohol as a natural product of the fermentation by which they are produced, 520 WINEWOOD WINE (Continued} the ferments consisting of the so-called " bloom " or living organisms that grow on the husks. Alcohol is added to many wines, such as port and sherry, and some of the Australian and Californian wines, in order to " fortify " them, as it is termed, against the acetic change that might otherwise subsequently take place of the smaller natural content of alcohol into acetic acid. The alcoholic strength of wines is by no means constant, but as sold, it may be said that port contains from 14 to 23 per cent. ; sherry from 14 to 1 8 per cent. ; claret from 6 to 12 per cent. ; Rudesheimer and other light wines about 8 or 9 per cent. ; beer, 5 to 6 per cent. ; small beer, 2 per cent. (See Yeasts.) It is said that to produce good wines, the grape juice must contain not less than 20 per cent, glucose, but not infrequently, sugar is added to the " must " or expressed juice of the grapes. In addition to alcohol, wines contain in many cases small quantities of sugar, acids (including tartaric acid), and so-called extractive matter of indefinite composition. Old wines, particularly port, are apt to deposit acid potas- sium tartrate upon long keeping. (See Tartar.) WINTERGREEN (OIL OF) See Gaultheria Oil. WITHERITE Natural barium carbonate. WOAD Blue colouring matter prepared from the leaves of Isatis tinctoria, which contains indican and is chemically identical with indigo. WOLFRAM See Tungsten. WOLFRAMITE See Tungsten. WOLLASTONITE A natural calcium silicate (CaSiO 3 ). WOOD The wood from various species of trees varies in structure, specific gravity, elasticity, and strength. White pine has an average sp. gr. of 0*39, larch a sp. gr. of 0-51, and teak a sp. gr. of 0-66. Wood consists of a mass of cells possessed of walls and containing a great variety of substances, such as cellulose, starch, resinous matters, essential oils, etc. All woods are liable to the attacks of fungus and the decomposition known as dry rot. (See Dry Rot.) More than seventy different kinds of moulds and fungi have been isolated f j om wood .or wood-pulp. In spruce, hemlock, balsam, and aspen, the progress of decay is distinctly indicated by a decrease WOOD 521 WOOD (Continued) in the content of stable cellulose and increase in that of unstable cellulose. The distillation or carbonization of wood is conducted in cast-iron retorts, and is now a large industry, yielding four prime products in addition to the gases which are generated namely, charcoal (which is left behind in the retorts), acetic acid (which is recovered as acetate of calcium from the pyroligneous acid contained in the watery distillate), wood or methyl alcohol, and tar. Wood creosote is ob- tained from the redistillation of the tar. (See Creosote (Wood).) The gases consist of about 15 per cent, hydrogen, n per cent, methane, 26 per cent, carbon dioxide, 41 per cent, carbon monoxide, and 7 per cent, hydrocarbons. Wood rich in rosin, such as that from pine-trees, yields also turpentine, and by pushing the distillation further, the rosin contained in the wood yields Rosin spirit distilling between 80 and 150 C. Rosin pine oil ,, 175 250 C. Blue rosin oil ,, 250 ,, 400 C. The following represents the results of a recently published analysis of oak-wood (Quevcus agrifolia) : Per Cent. Loss on drying ... ... ... 4*20 Benzene extract ... ... ... 0*50 Alcohol ... ... ... 4-33 Water ... ... ... 3-66 Soluble in cold 5 per cent, sodium hydroxide solution ... ... ... 18*71 Cellulose ... ... ... ... 45*48 Lignin ... ... ... ... 20*25 Pentosans not otherwise accounted for ... 1-89 Mannan (residual) ... ... ... None Galactan ,, .... ... ... 1-49 100-51 Green wood contains from 40 to 60 per cent, water, and ordinary dried woods contain about 50 per cent, carbon, 6 per cent, hydrogen, 40 to 42 per cent, oxygen, and i per cent, nitrogen. The following compilation of various wood -distillation products produced in Canada in 1918 is published by the Canadian Bureau of Statistics : 522 WOODWORMSEED OIL WOOD (Continued) Wood alcohol (crude, and sold as such) 875,024 gals. ^ (refined, ) 1,070,928 Acetate of lime ... ... ... ... 25,998,139^35. Acetic acid ... ... ... ... 1,772,223 Acetate of sodium 295,572 Acetone ... 3,458,810 Formaldehyde 1,154,902 Ketone oils ... ... ... ... 792,864 Acetic anhydride ... ... ... 44,981 Methyl acetate ... ... ... ... 132,121 Charcoal... ... ... ... ... 6,472,925 bush. and other miscellaneous products of a total collective value of $7,235,217- WOOD FIREPROOFING See Fireproofing (Wood). WOOD OIL See Tung Oil. WOOD-PULP is prepared for use in the manufacture of paper and artificial silk by a number of processes " mechanical," " semi-chemical," " sulphite," " sulphate," " soda," and so- called " kraft " all being directed to obtain the constituent cellulose dissociated from its accompanying substances. (See Paper.) WOOD-SPIRIT or METHYL ALCOHOL (CH 3 OH) So named from its derivation from wood tar, particularly beech- wood tar. (See Alcohols, p. 14.) WOOD'S FUSIBLE METAL See Bismuth. WOOL PITCH is the still residue from distillation of wool grease and wool fat, the stills being usually finished off at between 600 and 700 F. It is odourless, and made in several forms liquid to medium hard, the harder quality melting at about 100 F. It is used chiefly for making hot neck greases for tin-plate roll mills; also for insulating purposes and in paper-manufacturing. WOOL WAX See Waxes. WORMSEED OIL (Artemisia Oil) A yellowish essential oil of unpleasant odour with a sp. gr, of 0-93 ; soluble in alcohol, ether, etc., and distilled from the unexpanded flower-buds of the Artemisia maritima L. (South Russia and the Levant). It contains cineol, dipentene, terpineol, etc. An American variety is derived from the seeds of Cheno- podium ambrosioides, and contains cymene, sylvestrene, camphor, etc. WORM SEED OILXYLENOLS 523 WORMSEED OIL (Continued) Artemisia Anmta is stated to contain a ketonic body which upon oxidization yields a substance of the formula C 10 H 16 O, of sp. gr. 0-871, boiling-point 182 C., and refrac- tive index 1-4688. WORMWOOD (and WORMWOOD OIL) A very bitter herb (Artemisia absinthia) reputed as having some medicinal value. The oil obtained by distillation is of a greenish colour, contains thujone, phellandrene, etc., and is soluble in alcohol and ether ; sp. gr. about 0*925 to 0-96 ; refractive index, 1-46. (See Absinthe.) WORT See Alcohol, Beer, and Whisky. WOULFE'S BOTTLES are provided with two or more necks, and an illustration will be found under heading of Pneumatic Trough. (See p. 386.) WULFENITE Crystalline lead molybdate (PbMoO 4 ) found in some of the United States of America, etc. (See Molybdenum.) WURTZITE A native crystalline variety of zinc sulphide found in Montana, Utah, etc. XANTHINE (C 5 H 4 N 4 O 2 ) A white amorphous substance nearly allied to uric acid, from which it is obtainable by processes of reduction. XANTHOPHYLL See Chlorophyll and Plant Colouring Matters. XENON (X) Atomic weight, 130*2 ; sp. gr., 4-52. A very rare element, being one of the so-called argon group of atmospheric gaseous constituents isolated during recent years and contained in the heavier portion of liquefied air. It is calculated to be present in the air to the extent of i part by volume in 170,000,000 parts only. It gives a characteristic spectrum, is less volatile than argon, and has a density of - 0-65. It boils at - 109-1 C., at which tem- perature its density is 3 -063. XYLENE (Xylol) (C 8 H 10 or C 6 H 4 (CH 3 ) 2 ) A constituent hydro- carbon of coal naphtha. It is a colourless liquid of faint odour distinct from that of benzene, of which it is a homo- logue. The crude article, of sp. gr. about 0*86 to 0-89, is used as so-called " naphtha solvent," and as a raw material in the manufacture of dyes. In point of fact, there are three isomeric xylenes, that from coal tar consisting of a mixture of all three kinds. They are all colourless, mobile liquids, soluble in alcohol and ether. (See Coal and Naphtha. ) XYLENOLS (C 8 H 10 O or (CH 3 ),C 6 H 3 ,OH) Phenolic com- pounds of high boiling-point of which some six modifications 524 XYLENOLS YEA STS XYLENOLS (Continued) are known, forming part of the constituents of so-called " phenoloids " from blast furnaces. One of the xylenols is said to be a white, crystalline substance, soluble in water and alcohol. XYLIDINES (Meta, Orfcho, and Para) Liquid amines, used in dyestuffs. The meta compound (C 6 H 3 (CH 3 ) 2 NH 2 ) is a colourless oil which boils at 215 C., and of sp. gr. 0-9184. The ortho compound (C 6 H 3 (NH 2 )(CH 3 ) 2 ) is a yellow liquid, which boils at about 212 C., and of sp. gr. 981 to 984. The para compound (C 6 H 3 (CH 3 ) 2 NH 2 ) can be obtained in white crystalline and oily forms, of boiling-point 215 C., and sp. gr. 0-980. All are soluble in alcohol and ether. XYLONITE See Celluloid. X BAYS See Radio-activity and Rontgen Rays. YACCA GUM is a resin from Xanthorrhcea hastilis of Australia. It is soluble in alcohol, but insoluble in turpentine, linseed oil, benzol, and hydrocarbon solvents generally, but dis- solves readily in aqueous caustic alkaline solutions to deep red solutions, from which it can be reprecipitated by acids in a yellow flocculent form. It was an old source of picric acid, of which it can be made to yield 15 per cent., has been used in the manufacture of dyes, and is said to be of importance in the manufacture of linoleum, dyestuffs, and photographic chemicals. YEASTS Ordinary yeast (Saccharomyces cevevisia) consists of microscopic round or oval vegetable cells of about j--^ inch in diameter which multiply by gemmation or budding, and is employed in various processes of fermentation wines, beers and^spirits as also in bread-making. Fermentation induced by yeast can only take place between 3 and 35 C., and the organism is killed by a greater alcoholic strength than represented by a solution of 14 per cent. It loses its activity when dried and heated to 60 C. or exposed to the action of antiseptics. The fermentation induced by yeast is independent of the cell walls, and is really due to the enzyme termed zymase present in their contents. Brewery yeast has a considerable food value, and a food is now prepared from it resembling meat extract in flavour. There are many varieties of yeast of distinctive properties. Recently a process has been perfected in Germany for YEA STS YTTRIUM 525 YEASTS (Continued) inoculating waste liquors from sugar refineries, distilleries, paper and starch works, with a particular variety which grows quickly and does not produce alcohol. The yeast increases in quantity at the expense of the carbohydrates in the waste water and added ammonium salts, and is ulti- mately separated and dried. It is stated that 100 parts of sugar, or its equivalent, present in the waste and 37-5 parts of nutritive ammonium salts yield 150 parts of compressed yeast, which, after dry- ing, contains from 40 to 60 per cent, of albuminous matter. This dried yeast, so rich in nitrogenous matter, is used as cattle fodder, and is reported as fit for human food to replace a large proportion of the necessary albuminoids. (See also Enzymes and Zymase.) YLANG-YLANG A yellow essential oil distilled from the flowers of Cananga odorata (indigenous in the Malay Archi- pelago, and cultivated in the Philippines) of which varieties are known as " cananga " and " manila " oils. They contain methyl and benzyl acetates and benzoates, linalool, geraniol, eugenol, etc. The sp. gr. of ylang-ylang is given as 0-9 to 0-96, and its rotation - 1 7 to 50, varying with the source of the oil, which is soluble in alcohol and ether, and is used in perfumery. YOHIMBINE (CagH^NjjOJ A crystalline poisonous alkaloid, extracted from Lorynanthe yohimbe, used in medicine. YOUNG FUSTIC The heartwood of a sumac (Rhus cotonus) used in the leather industry. YTTERBIUM or NEO- YTTERBIUM (Yb) Atomic weight, 173-5. A very rare element found in the mineral gadolinite (ytterbite) and associated with yttria. An oxide (Yb 2 O 3 ) is known, also a chloride (YbCl 3 ) and a sulphate (Yb 2 (SO 4 ) 3 ). YTTRITE Gadolinite. YTTRIUM (Yt) Atomic weight, 887 ; sp. gr., 3-80 ; and melting-point, 1,250 C. A very rare element found in gadolinite (ytterbite), xenotimmne, and samarskite. Like ytter- bium it is associated with the boron group of elements. It is a greyish-black powder which is capable of decomposing water to some slight extent at the ordinary temperatures and more rapidly when heated, forming the oxide Yt 2 O 3 , from which the metal can be obtained by electrolysis. It is very soluble in acids, and in addition to the oxide, a number of compounds are known, including a carbonate 526 YTTRIUM ZINC YTTRIUM (Continued} (Yt 2 (C0 3 ) 3 ), chloride (YtCl 3 ), bromide (YtBr 3 ), iodide (YtI 3 ), nitrate (Yt(NO 3 ) 3 ), and sulphate (Yt 2 (SO 4 ) 3 ), all of which excepting the carbonate are more or less soluble in water. The compounds of yttrium closely resemble the aluminium compounds, and are used in the manufacture of incan- descent gas mantles. ZARATITE A kind of nickel carbonate ore. ZEOLITES (Zeoliths) are natural deposits of an opaque vitreous character abundantly diffused in nature, which may be described as double hydrated silicates of aluminium and calcium. When treated with acids they partially dissolve, leaving the silica in a gelatinous state. Stilbite and analcime are two zeolites. (See Permutit.) ZINC (Zn) and its Compounds Atomic weight, 65 ; sp. gr., about 6-9 ; melting-point, 419*4 C. Zinc is not met with in nature in the metallic state, but occurs as calamine, or zinc spar (zinc carbonate, ZnCO 3 ), in Silesia and the United States of America, and it is also worked in Belgium. Blende (zinc sulphide, ZnS) is found and worked to some extent in England, while in New Jersey a red zinc oxide (ZnO), the colour of which is due to manganese, is found in consider- able amount. Zinc also occurs in franUinite (a compound oxide of zinc and iron), in gahnite (a compound oxide of zinc and aluminium), and a number of other minerals. The chief supply of spelter (as zinc is also known) comes from Australia, and is sufficient to meet all British wants. (See also Marmatite.) Zinc boils at 930 C., and can be distilled at 1,040 C. It is a crystalline metal, has a bluish-white appearance, is fairly ductile and malleable, and only tarnishes slightly in moist air. Evidence pointing to the existence of three allo- tropic forms of the metal is on record. It forms alloys with tin, copper, and antimony in all proportions, and is a component part of many others containing lead and bismuth. Brass is composed of 2 parts copper and i part zinc. The zinc of commerce is partly produced by a process of distillation from a mixture of the oxide of that metal with carbon the ores being first roasted so as to convert any carbonate or sulphide into the oxide. There is, however, an electrical process of manufacturing the metal, applicable even to complex and low-grade ores, which are not amenable to the distillation process, depending upon the electrolysis ZINC AND ITS COMPOUNDS 527 ZINC (Continued) of a solution of the sulphate (produced by dissolving the metal out of the roasted ore by sulphuric acid). In this process, electrodes of lead and aluminium are used, the zinc being deposited on the cathode (aluminium pole), and subsequently stripped off and melted into ingots of 99^95 per cent, purity. The metal is largely used for the production of brass, roofing, as a lining for packing cases, making alloys, and for galvanizing (coating) iron, to which it gives durability by preserving it from atmospheric oxidation. Zinc Oxide (ZnO) (zinc white) is produced as a soft white powder when the metal is burnt in the air. It is insoluble in water, and is used in medicine and as a pigment, having the advantage of not being blackened by exposure to the air when sulphuretted hydrogen is contained therein. The hydroxide (Zn(HO) 2 ) is produced in a white flocculent form when an alkaline hydrate is added to a solution of a zinc salt. It is soluble in an excess of alkali. Zinc Acetate (Zn(C 2 H 3 O 2 ) 2 .3H 2 O) is a white, crystalline salt, soluble in water, used as a mordant in dyeing. Zinc Dichromate (ZnCr 2 O 7 ) is an orange-coloured powder, insoluble in water, used as a pigment. Zinc Fluoride (ZnF 2 ) is a white powder, insoluble in water, used in the ceramic industries. Zinc Chloride (ZnC1 2 ) is prepared by dissolving the metal in hydrochloric acid and concentrating to that state in which it solidifies upon cooling, when it is cast into sticks. It is a deliquescent soft compound very soluble in water, and can be distilled without decomposition. Commercially it is also prepared in the form of a strong solution of io2Tw., and is used in connection with soldering and as a wood preservative, while a paste consisting of a mixture of the chloride with zinc oxide is employed in dentistry, under the name of " oxychloride," as a stopping for teeth. Zinc Sulphate is manufactured by roasting the mineral sulphide under careful conditions and dissolving out the sulphate thus produced, and can also be obtained by dis- solving the metal in dilute sulphuric acid. It crystallizes with water in combination as ZnSO 4 ,7H 2 O, is very soluble in water, and somewhat efflorescent. It becomes anhydrous upon heating to about 300 C., and is decomposed at a higher temperature into sulphur dioxide, oxygen, and zinc 528 ZINC ZIRCONIUM ZINC (Continued) oxide. It is a particularly poisonous salt, and finds use in medical practice as an astringent and antiseptic, and as a mordant in calico-printing. Zinc Sulphide (ZnS), when precipitated from a solution of a zinc salt by addition of an alkaline sulphide solution or passage of hydrogen sulphide, is a practically white amorphous substance insoluble in acetic acid, and is used to some extent as a pigment in place of white-lead. (See Lithopone.) Zinc Carbonate (ZnCO 3 ) in dry form is a white amorphous powder, insoluble in water, and used as a pigment and in medicine, whereas Zinci carbonas of the Pharmacopoeia is a basic compound having the composition expressed by ZnC0 3 ,2Zn(HO) 2 ,H 2 0. All the soluble salts of zinc are poisonous. ZINC-BLENDE See Zinc and Sulphur. ZINC DUST (ordinary commercial) is a fine grey powder susceptible of rapid oxidation and firing ; in great request in dyeworks as a reducing agent. It consists of 40 per cent, zinc, 2^ per cent, lead, 4 per cent, cadmium, 50 per cent, zinc oxide, and 3^ per cent, zinc carbonate. ZINC-COPPER COUPLE Zinc coated with metallic copper, capable of decomposing water at its boiling-point with evolution of hydrogen and formation of zinc oxide. It can also be employed to break up a number of organic liquids by electrolytic action. " ZINC FOEMOSUL " is described as basic zinc formaldehyde sulphoxylate, being a greyish-white powder, insoluble in water, but which exercises reducing power when boiled with very dilute acids, or at high temperatures in their absence. It is advocated for use in the autoclave and Twitchell processes of fat splitting, and is claimed to assist in the bleaching of the resulting glycerine. ZIRCONIUM (Zr) Atomic weight, 90-6; sp.gr., 6-4; melting- point, between 1,530 and 2,000 C. Zirconium is a rare element found in nature in the form of silicate (ZrSiO 4 ) in the mineral zircon, and obtained by reduction of the oxide. When metallic zirconium is heated in the air it oxidizes slowly. Zirconium is soluble in hot acids, and one method of preparing it free from iron and alumina is based upon the production of a basic sulphate (5ZrO 2 .2SO 3 ). The hydroxide Zr(OH 4 ), like the oxide, is insoluble in water, and loses 2H 2 O at 550 C. ZIRCONIUM ZYMA SE 529 ZIRCONIUM (Continued) It belongs to the same group of elements as titanium, and, like silicon, it is known both in crystalline and amorphous forms. There are several nitrates, including the normal salt (Zr(NO 3 ) 4 ) and a sulphate (Zr(SO 4 ) 2 ), which are soluble in water, a chloride (ZrCl 4 ), which is de- composed by water but is soluble in alcohol, and a number of other compounds bearing a resemblance to those of thorium and silicon. Zirconium Acetate (Zr(C 2 H 3 O 2 ) 3 OH) is a white, crystal- line, soluble salt, used for weighting silk. Zirconium Carbide (ZrC 2 ) decomposes water and finds use as an abrasive. Zirconium Oxide (ZrO 2 ) is a heavy, white, amorphous powder, obtained by heating the hydroxide Zr(OH) 4 , and is a valuable refractory material which finds application not only in the preparation of incandescent gas mantles, but as an abrasive, in ceramics, and in the compounding of refractory and acid-proof utensils and enamels. During the recent war, zirconium in small amount (0*34 per cent.) was introduced into the steel used by the French in making armour-plate, as in association with 3 per cent, of nickel it was found to add to its tensile strength. A silvery white crystalline alloy of zirconium with aluminium has been prepared of the composition Zr 3 Al 4 . ZIRCONS Natural silicate of zirconium (ZrSiO 4 ) found in Brazil and elsewhere. One such deposit, known as brazilite, is said in a semi-manufactured form to contain about 80 per cent, zirconium oxide. This product is employed as a re- fractory in the making of " zirkite " bricks and cement. Another Brazilian deposit is known as orvillite, and contains about 72 per cent. ZrO 2 . ZYMASE (Invertase or Invertin) An enzyme produced by yeast cells and contained therein, which is capable of in- ducing fermentative and hydrolytic changes independently of the cells. Sometimes the plural term zymases is used, as meaning the same thing as enzymes, but that should be avoided. (See Enzymes, Fermentation, Invertase, and Yeasts.) 34 530 ACICULARBARM ADDENDA ACICULAR (Crystals) Needle-shaped. ACIDIMETRY The determination of amount of acid con- tained in a solution, by titration with a standard alkali solution. (See Volumetric Analyses.) ACYL RADICALS The radicals left after removal of OH from organic acids for example, CH 3 .CO. (acetyl), C 2 H 5 .CO. (propionyl), etc. ALIPHATIC The distinctive term applied to all carbon compounds with open chains (as those derived from the paraffin and olefine hydrocarbons), as distinct from those containing an aromatic nucleus. The fatty acids are, for example, members of the aliphatic series. (See Chains.) ALIQUOT A definite proportion of a given quantity. ALKIMETRY The determination of amount of alkali con- tained in a solution, by titration with a standard acid solution. (See Volumetric Analyses.) ALKYLENES The divalent residues OH 2W . (See defines.) ALKYLS The monovalent radicals (C"H 2 n-f i) of the mono- valent alcohols like methyl and ethyl. AMMETER An instrument for determining the strength of electrical currents in terms of amperes. AMPERE The unit of electrical current which, when passed through a solution of silver nitrate in water, causes the deposition of silver at the rate of ox>oiu8 grm. per second. AROMATIC COMPOUNDS Those derived from benzene, with rings or closed chains of carbon atoms. ARYLS The group of aromatic radicals ; aniline is typical of the so-called arylamines. ASYMMETRY The want of symmetry in atomic arrange- ment. BALANCE See Scales. BARM See Yeasts. BASICITY COPPER-ZINC COUPLE 531 BASICITY The number of hydrogen atoms contained in an acid which can be replaced by a base. (See Acids.) BROWNIAN MOVEMENT See Colloid. CALX The residual matter resulting from calcination of mineral matter. CENTIGRADE (Celsius) See Heat, p. 241. CENTIMETRE See Weights and Measures. CHAINS Atomic arrangements of several classes. Open chains have terminal atoms not mutually in combination, by which, for example, aliphatic combinations are character- ized ; thus, acetic acid is represented constitutionally by the formula H O H 0-H In closed chains, the terminal atoms are mutually combined, forming a ring, as in benzene : CH CH/ \CH X/ CH CHROMOGENS The parent group of dyes formed from chromophores by substitution in hydrocarbons, and when, in addition, a strong basic or acid group (such as NH 2 or .SO 2 .OH) is also present, dyes are obtained. CHROMOPHORES The particular atomic groupings character- istic of coloured organic compounds, such as .N : N and NO 2 . (See Chromogens.) COAGULATION The more or less solidification of a " sol " to a gelatinous mass ; solution of egg albumin is, for example, coagulated by heating or by precipitation with acetic acid. (See Albumins and Colloid.) COAL TAR See Coal, p. 122. COPPER-ZINC COUPLE An appliance consisting of zinc and precipitated. copper deposited thereon, used by Gladstone and Tribe in preparing methane from magnesium methyl iodide and in the study of a variety of other chemical changes induced by the couple. 532 COULOMB DISPERSOIDS COULOMB The unit quantity of electricity capable of de- positing i -ii 75 mgrm. of silver, and delivered by i ampere flowing in i second. 96,540 coulombs =i faraday. CUBIC CENTIMETRE See Weights and Measures. CUPOLA Furnace such as used for melting metals. (See Cupellation.) CYANATES See Cyanic Acid. CYCLIC A term applied to compounds containing a ring of atoms in the nucleus. Carbocyclic compounds are those in which the ring or closed chain is composed entirely of carbon atoms, such as the naphthenes and the benzene derivatives, including naphthalene and anthracene. (See Chains.) DEACON'S PROCESS See Chlorine, p. 109. DEHYDRATION The removal of water from substances. DENITRATION (i) The removal of nitrogen oxides from sulphuric acid (see p. 469). (2) The removal or change of the nitro group in organic compounds. DEXTRO-ROTATORY The power of rotating the ray of polarized light to the right. (See Invertase, p. 265, and Polarization, p. 387.) DIACTINIC The property of transmitting actinic rays. (See Actinism.) DIAMIDE See Hydrazine. DI AMINES Organic compounds containing two amino groups, such as ethylene diamine (C a H 4 (NH 2 ) 2 ) (a colourless liquid of ammoniacal odour which boils at 123 C.). DIAZO GROUP ( - N 2 - ), as it exists, for example, in diazo- benzene chloride (C 6 H 6 - N : N - Cl). DIOXIDES Compounds containing two proportions of oxygen to one of base as, for example, barium dioxide (BaO 2 ). DIOXIMES Compounds containing two oxime groups, such as benzil dioxime (C e H 5 ) 2 C 2 (N.OH) 2 . (See Oximes.) DISPERSION (i) A term used in connection with colloidal chemistry. (See Colloid.) (2) The separation of light into its different coloured rays. DISPERSOIDS See Osmosis. DISULPHIDES-HEXOSES 533 BISULPHIDES Compounds containing two proportions of sulphur to one of base as, for example, carbon disulphide (CS 2 ). DYADS See Valencies. DYNE The unit of force in the centimetre-gram-second system, or that which, acting upon a mass of I gram for i second, produces unit velocity (i centimetre per second;. ELEOPTENES See Stearoptenes. EMANATIONS See Radio-activity. ERG The unit of work in the centimetre-gram-second system of physical units, or the work done by the force of i dyne moving through i centimetre. One joule = io 7 ergs. ESTERIFICATION The process of formation of esters. (See Esters.) ETHENYL The radical CH 3 .C i, as it exists, for example, in the crystalline base ethenyl-diphenyl amidine NHC 6 H 5 . ETHIDES Combinations of metal? with the radical ethyl, such as zinc ethide (Zn(C 2 H 5 ) 2 ). ETHYL The radical CH 3 CH 2 , or C 2 H 5 , as contained in ethyl alcohol (C 2 H 5 HO). (See Radicals.) FAHRENHEIT See Heat, p. 241. FARADAY See Coulomb. FLUOSILICATES Salts of hydro-fluosilicic acid (H 2 SiF 6 ). (See Silicon, p. 434.) FOOT-POUND The unit of work required to lift a pound mass through a distance of i foot. FRAUNHOFER LINES See Spectroscope, p. 457. GAY-LUSSAC TOWER See Sulphuric Acid, p. 469. GLOVER'S TOWER See Sulphuric Acid, p. 469. GLUCOSANES Polysaccharoses which, upon hydrolysis, yield hexoses. GRAMME (Gram) See Weights and Measures, p. 517. HEXOSES A group of carbohydrates, including dextrose and fructose, divisible again into other groups exhibiting variously the characters of aldehydes and ketones. 534 HISTONES MELTING-POINTS HISTONES A certain class of proteins precipitable from solution by ammonia. HORSE-POWER The unit of power being equal to 33,000 foot-pounds of work per minute (see Foot- Pounds), i '34 horse-power = i kilowatt, and i horse-power = 1-014 metric horse-power. HUBL NUMBER Iodine value of fats and oils. (See Iodine Value, p. 266.) HYDRAZINE (Diamide) (N 2 H 4 or NH 2 .NH 2 ) A colourless liquid which boils at 113*5 C., made by reduction from nitrosamine. The name is also given to an organic com- pound containing two amido groups. (See Nitrosamines.) IMIDO (IMINO) GROUP The divalent group (:NH). (See Imides, p. 259.) INDAMINES A group of aniline dyes including " phenol blue " ((CH 3 ) 2 N .C 6 H 4 .N : C 6 H 4 : O). INDOPHENOLS A group of aniline dyes. INVERSION See Invertase, p. 265, and Walden's Inversion. JOULE io 7 absolute units of work (ergs) represented by the energy expended in i second by i ampere in i ohm. One joule "=9-239 1 calories. KET08ES Sugars containing the group carbonyl : C : O. (See Metallic Carbonyls.) KILO (Kilogram) See Weights and Measures, p. 518. KINETIC ENERGY That possessed by a body in virtue of its motion. KINETIC THEORY This assumes that gas pressure is due to bombardment of moving particles. (See Gases, p. 218.) LACTIDE (C 6 H 8 O 4 ) An anhydride of lactic acid which melts at 125 C. L.33VO -ROTATORY The property of effecting the rotation of a ray of polarized light to the left. (See Invertase, p. 265, and Polarization, p. 387.) LEUCO BASES Colourless compounds produced by reduction of dyes which are reconverted by oxidation into dyes. MELTING-POINTS The temperatures at which fusible sub- stances melt, or become liquid, and as these are affected by pressure they are usually referred to normal pressure (760 mm.). METABOLISMOHM 535 METABOLISM The various changes resulting from the conversion of food in living organisms METHYL The monovalent (univalent) radical CH 3 . (See Alcohol (Methyl), p. 14.) MINERAL ACIDS A general name given to all acids other than those of organic character. MONAD See Valencies, p. 498. MUCINS A class of glyco-proteins which occur in some secre- tions and yield albumin and carbohydrate upon hydrolysis. MYDRIATIC The property of causing dilatation of the eye pupil, exhibited by a number of substances, including hyoscyamine and homatropine. MYOTIC The property of causing contraction of the eye pupil, exhibited by a number of substances, including eserine. (See Calabar Bean.) NITROGENIZE Combination of nitrogen or nitrogenous groups with other substances. NITROGENOUS A term applied to substances containing nitrogen as an important constituent, such as fertilizers and proteins. NITRO-GROUP (Nitryl) (-NO 2 ) As present in nitrobenzene (C 6 H 5 NO 2 ), for example. NITROMETER An apparatus for measuring nitrogen gas as evolved from chemical interactions. NITROSAMINES A series of yellow, aromatic, volatile bodies derived from the secondary bases containing the imino group :NH by treatment with nitrous acid, such as dimethyl nitrosamine (CH 3 ) 2 N.NO. (See Hydrazine.) NITROSO COMPOUNDS are those containing the group - N : O as, for example, nitrosobenzene (C 6 H 5 NO). NITROSYL The monovalent radical - N : O as it exists in a number of compounds, such as nitrosyl chloride (NOC1), an orange-coloured gas resulting from the direct combination of nitric oxide with chlorine. NITROXYL The monovalent radical -NO 2 as it exists in compounds such as nitroxyl fluoride (NO 2 F), a colourless gas resulting from the direct union of fluorine and nitric oxide. OHM The international unit of resistance is that offered by a column of mercury 106*3 cm> m length, 14-452 1 grms. in mass, and at the temperature of melting ice, to an unvary- ing electric current. 536 ORGANIC PRESSURE ORGANIC See Carbon and Organic Matters, p. 84, ORIENTATION The relative positions of substituted con- stituents in relation to the parent substances and each other. OZONIDES Combinations of ozone with unsaturated hydro- carbons and alcohols as, for example, ethylene ozonide (C 2 H 4 + 3 ). PENTOSANES Gums which yield pentoses upon hydrolysis as, for example, cherry gum, which yields /-arabinose. PENTOSES Saccharoid bodies containing five carbon atoms, such as /-arabinose (C 5 H 6 O(OH.) 4 ), and which yield furfuraldehyde or methyl furfuraldehyde when boiled (hydrolized) with hydrochloric acid. (See Carbohydrates.) PENTOXIDE An oxide containing five atoms of oxygen in the molecule for example, phosphorus pentoxide (P 2 O 5 ). PEPTIZATION See Colloid. PHAGOCYTES Cells which destroy bacteria, etc., in the blood, and distinct from leucocytes, which are also said to exercise phagocytic activity. This last-named activity is said to be increased by other substances, known as Opsonins. PHENOLATES Compounds formed from phenols and metals by substitution of the hydroxyl hydrogen for example, sodium phenolate on phenate (NaC 6 H 5 O), which is made by dissolving phenol (C 6 H 5 HO) in caustic soda solution. PHENOL BLUE See Indamines. PHOSPHORYL The trivalent radical | P : O, as it exists in combinations such as phosphoryl chloride (POC1 3 ), a colourless, fuming liquid formed by the action of water upon phosphorus pentachloride, etc. PHTHALEINS A group of organic compounds (dyes) con- taining two phenol residues prepared by the action of phenols upon phthalic anhydride, including phenol- phthalei'n and fluoresce'in. They are nearly related to another colourless group known as "phthalines," which are leuco-compounds of the phthalei'ns. PLATINAMINES (Platosammines) A number of basic com- pounds formed from platinum and ammonia, many of which are of complex character. One such salt has the composition Pt(NH 3 ) 2 Cl 2 . (See also Platinum, p. 384.) POLARISCOPE See Polarization. PRESSURE (Atmospheric) See Barometer, p. 51. PROPIONYL-SULPHURYL 537 PROPIONYL The acyl group, CH 3 .CH 2 .C : O, left after removal of HO from propionic acid. PROPYL The monovalent radical group C 3 H 7 , or CH 3 .CH 2 . CH 2 . (See Propyl Alcohol, p. 15.) PROTAMINES The simplest proteins, including salmine and and sturine, as isolated from fish testicles. PURINE GROUP A number of so-called cyclic diureides, including uric acid. QUADRIVALENT Same as tetravalent. (See Valencies.) QUINTESSENCE An extracted essence or essential oil. REAUMUR See Heat, p. 241. RED LIQUOR See Aluminic Acetate, p. 26. RED OIL Commercial oleic acid. RHEOSTATS Instruments for regulating the flow of electric currents and for measurements, thus affording the means of controlling the amount according to Ohm's law. (See Ohm.) RHIZOME Underground stems or roots. RING, BENZENE See Chains. SAND-BATH A laboratory contrivance to secure a fairly regulated heat, consisting of an iron saucer containing a thin layer of sand heated by a lamp below, and on which the vessel to be heated is placed. SESQUIOXIDES Oxides like ferric oxide (Fe 2 O 3 ) in which the proportions of metal and oxygen are as two to three. SORPTION The combination of water or other liquid with a curd or colloid body, as distinct from mere entanglement. (Compare Colloid and Adsorption.) SPRENGEL PUMP See Pumps (Exhaust). STEAROPTENES The solid constituents of certain essential oils, the liquid parts being designated eleoptenes. (See Attar of Roses.) STEREO-CHEMISTRY The study of the relative positions occupied by atoms or groups within molecular bodies. SUB A chemical prefix used to indicate a lower valency or basic substances, such as lead suboxide (PbO 2 ), and the subacetate or basic acetate of lead (Pb(C 2 H,OA, Pb(HO) 2 ). SULPHURYL The divalent radical : SO 2 as occurring, for example, in sulphuryl chloride (SO 2 C1 2 ), which can be prepared by the direct union of chlorine and sulphur 538 SULPHURYLUREOMETER SULPHURYL (Continued) dioxide. It is a colourless liquid which boils at 70 C. and is decomposed by water, producing hydrochloric and sulphuric acids. SULPHONIC ACIDS Organic combinations containing the monovalent group .SO 2 .OH in association with alkyl or aryl residues. (See Sulphonation.) TAWING The dressing of skins, or tanning processes with alum or chromium salts. THERMAL UNIT See Heat, p. 244. THERMOPILE (Thermocouple) An apparatus constructed upon the knowledge that an electric current can be pro- duced in a closed circuit by heating the point of contact of two dissimilar metals. The electromotive force (E.M.F.) of a bismuth-antimony pair when the junctions are kept at o and 100 is only o'Oii5 volt, but using series of such pairs so arranged that the alternate junctions can be heated, the current is increased proportionally to the number of pairs. THIAZOLE An organic colourless liquid, boiling at 117 C., represented by the formula CH.N CH.S THIO-ALCOHOLS See Mercaptans. TINCTURES Alcoholic solutions of drugs ; more dilute than extracts. (See Extracts, p. 192.) TOXALBUMINS Products of protein nature which are distinct from ptomaines and include the poisons of snake bites and others of plant origin, such as abrin (the poison- ous principle of Abrus pvecatomts jequirity) and ricin (a poisonous ingredient of the castor-oil plant). TREE-LEAD The arboreal form of lead as deposited on a bar of zinc when placed in an aqueous solution of a lead salt, or formed electrolytically, as described under Lead, p. 290. ULTRA-VIOLET RAYS Light rays forming part of the spectrum so short that the human eye is not sensitive to them. (See Spectroscope.) UREO METER An apparatus for quantitatively determining urea contained in urine by measuring the amount of nitrogen gas evolved in its decomposition, using sodium hypobromite in sodium hydrate solution. VINA SSEZYMOGENS 539 VINASSE Residue left after fermentation of beet molasses, containing potash salts and some nitrogenous matter which qualify it for use as a fertilizer and cattle food. (Compare Begasse.) VOLT=io 8 absolute units is the electromotive force which, applied to i ohm, will produce in it a current of i ampere. (See Ohm.) VOLTAIC CURRENT See Electricity. WALDEN'S INVERSION Concerns the conversion of optic- ally active substances into others of opposite rotation, such as that of /-chlorsuccinic acid into the rf-isomeride, and /-malic acid into the ^-malic acid, by means of chemical reagents. (Compare Polarization and Racemic Com- pounds.) WATT The power of an electric current of i ampere flowing under a pressure of i volt, and approximately y^ part of i horse-power. WOOL FAT Contains a number of fats and cholesterin. (Compare Adeps Lanae and Suint.) ZERO (Absolute) See Notable Temperatures, p. 242. ZYMOGENS Substances from which it is conjectured that the enzymes are formed in the organism. 1R1NTED IN GREAT BRITAIN BY BILLING AND SONS, LTD., GUiLDFORD AND ESHER LITERATURE OF THE CHEMICAL INDUSTRIES On our shelves is the most complete stock of technical, industrial, engineering and scientific books in the United States. The technical liter- ature of every trade is well represented, as is also the literature relating to the various sciences, both the books useful for reference as well as those fitted for students' use as textbooks. A large number of these we publish and for an ever increasing number we are the sole agents. ALL INQUIRIES MADE OF US ARE CHEER- FULLY AND CAREFULLY ANSWERED AND COMPLETE CATALOGS AS WELL AS SPECIAL LISTS SENT FREE ON REQUEST D. VAN NOSTRAND COMPANY Publishers and Booksellers 8 WARREN STREET NEW YORK YC 32574 Engini 48J5JH neering UNIVERSITY OF CALIFORNIA LIBRARY