Jpanung aab Jtabor. LIBRARY II OF THE 6| | University of Illinois, f CLASS. BOOK. VOLUME. 5 Accession No University of Illinois Library Urbana-Champaign Lists for Student Reading No. a January 19x1 Representative list of 160 of the best foreign novels in English translation From the Dutch Conscience . . . The lion of Flanders Conscience . The poor gentleman Couperus Majesty Dekker • * • Max Havelaar Vosmaer U I ■ The Amazon Wallis m . .In troubled times From the French About . • The king of the mountains Balzac ' The Chouans Balzac . . . • • Eugenie Grandet Balzac p ^ re Goriot Bazin The nun Bourget The d *sciple Cherbuliez . .Samuel Brohl & Company Coppee T ™ e riches Daudet J ack Daudet . Tartarin of Tarascon Dumas . . . The Count of Monte Cristo Dumas . The three musketeers Ja n-Ed2-3M Erckmann -Chatrian . . The conscript Erckmann-Chatrian . . Madam TheVese Feneloo . Adventures of Telemachus Feuillet . Romance of a poor young man Flaubert . . . Madame Bovary France . . Crime of Sylvestre Bonnard France Thais Gautier .... Captain Fracasse Gautier . . . The romance of a mummy Goncourt .... Ren6e Mauperin Gras .... The reds of the Midi Greville Dosia Halevy .... The abbe* Constantin Hugo Les miserable s Hugo . . . Notre Dame de Paris Hugo .... Toilers of the sea Huysmans En route La Fayette . . The princess of Cleves Lamartine Graziella Lesage Gil Bias Loti .... An Iceland fisherman Maupassant .... Pierre and Jean Merimee Carmen Ohnet . . . . . The ironmaster Prevost Manon Lescaut St Pierre .... Paul and Virginia Saintine Picciola Sand Consuelo Sand The snow man Sandeau .... Mile de la Seigliere Souvestre . . An attic philosopher Stael-Holstein Corinne Stendhal . . The chartreuse of Parma Stendhal Red and black Sue .... The wandering Jew Theuriet . . . The marriage of Gerard Verne . Around the world in 80 days Verne . . 20,000 leagues under the sea Vigny Cinq-Mars Zola The downfall Zola Lourdes From the German Auerbach On the heights Chamisso .... Peter Schlemihl Dahn ... A struggle for Rome Ebers . . . An Egyptian princess Ebers Homo sum Eckstein . . . Quintus Claudius Fouque Undine Franzos .... The chief justice Frenssen Jorn Uhl Freytag Debit and credit Freytag . . . The lost manuscript Goethe . Wilhelm Meister's apprenticeship Gotthelf . . . Ulric the farm servant Gutzkow . . . Through night to light Hacklander . . . Behind the counter Heyse In Paradise Hillern . . . The vulture maiden Meyer .... The monk's wedding Nathusius Elizabeth Reuter In the year '13 Reuter . Old story of my farming days Richter Titan Rosegger . . . The forest schoolmaster Rosegger .... The godseeker Scheffel Ekkehard Schubin Boris Lensky Spielhagen . . Hammer and anvil Storm Immensee Sudermann .... Dame Care Suttner .... Lay down your arms Taylor Klytia Wolff The robber count From the Greek Bikelas Loukis Laras Xenos Andronike From the Italian de Amicis Cuore d'Annunzio . « . The virgins of the rocks d'Azeglio . . . The maid of Florence Barrili . . The eleventh commandment Deledda .... After the divorce Fogazzaro The saint Fogazzaro .... The sinner Manzoni .... The betrothed Ruffini Doctor Antonio Serao . . . The land of Cockayne Verga . The house by the medlar tree From the Oriental From the Bengali . The chieftain's daughter From the Chinese . . Shueypingsin From the Russian Andreiev .... The red laugh Danilevski . . Princess Tarakanova Dostoievski .... Buried alive Dostoievski . Crime and punishment Gogol Dead souls Gogol Taras Bulba Gontcharov . ... .A common story Gorky .... Foma Gordyeeff Gorky The spy Korolenko . . The blind musician Lermontov . A hero of our own time Merejkovski . . The death of the gods Stepniak . . The career of a Nihilist Tolstoi .... Anna Kardnina Tolstoi Resurrection Tolstoi .... War and peace Turgenev . . . Fathers and children Turgenev Rudin Turgenev Smoke From the Scandinavian Andersen Improvisatore Bjornson Arne Bjornson .... SynnOve Solbakken Bremer The neighbors Drachmann Nanna Ewald, Carl The old room Ewald, H. F. Waldemar Krone's youth Jacobsen Siren voices Janson . . . The spell-bound fiddler Kielland .... Skipper Worse Lageriof . . The story of Gdsta Berling Lie . . The commodore's daughter Lie i The pilot and his wife Mailing . . . f . The governor's wife Rydberg . , L . The last Athenian "Nljrom the Slavic Jokai .... The lion of Janina Kraszewski f ~ .... The Jew Mikszath . > . . X> St Peter's umbrella Sienkiewicz , . \\ . . The deluge Sienkiewicz . • • Q uo vadis Svetla Maria Felicia Vazoff . . Vs /\ . . Under the yoke From the Spanish Alarcon The three-cornered hat Aleman Guzman of Alfaraque Caballero . The sea gull Cervantes Don Quixote Isaacs Maria Mendoza Lazarillo de Tormes Palacio Valdes Jose* Palacio Valdes Marquis of Penalta Perez Galdos . Dona Perfecta Perez Galdos Leon Roch Rizal • \ Friars and Filipinos Dona Luz Valera . Pepita Jimenez All of the titles listed above are to be found in the University of Illinois Library. Return this book on or before the Latest Date stamped below. A charge is made on all overdue books. U. of I. Library v QIC 15 1938 14685-S AGRICULTURAL CHEMISTRY KEGAN PAUL, TRENCH, TRDBNER & CO., LTD. THE AGRICULTURAL SERIES. This series is designed to throw some light upon the possible remedies for the prevalent depression in agriculture. The volumes are all by men with a practical knowledge of their subject, and will include, besides the present work, volumes on the following subjects : — FARM BUILDINGS and Economical Agricultural Ap- pliances. By W. J. Malden, author of " The Potato in Field and Garden," etc. Crown 8vo, 5 s. {Published. BOTANY. By Wm. Fream, LL.D. PHYSIOLOGY AND FEEDING. By T. B. Wood and R. H. Adie. AGRICULTURE. By Robert Menzies, M.A., Examiner in Agriculture, Cambridge University. HORTICULTURE. By E. Pillow, Organizing Secre- tary to the Norfolk County Council ; and W. K. Woodcock, F.R.H.S. CONVERSION OF ARABLE LAND INTO PAS- TURE. By W. J. Malden. And others on similar subjects. THE VILLAGE LIBRARY. KILLBOYLAN BANK; or, Every Man his own Banker. Being an account of how Killboylan Characters concerned them- selves about Co-operative Credit. By E. W. Lynch. Crown 8vo, -3)S. 6d. PIG-KEEPING FOR PROFIT By W. J. Malden. Crown 8vo, 2s. 6d. Other volumes will follow. London: PATERNOSTER House, Charing Cross Road. AGRICULTURAL CHEMISTRY BY K. H. ADIE, M.A., B.Sc. LECTURER IN CHEMISTRY OF ST. JOHN'S COLLEGE, CAMBRIDGE AND T. B. WOOD, M.A. SECRETARY AND LECTURER ON AGRICULTURAL CHEMISTRY TO THE CAMBRIDGE AND COUNTIES AGRICULTURAL EDUCATION SCHEME IN TWO VOLUMES VOL. I. London KEGAN PAUL, TRENCH, TRUBNER & CO., Ltd. PATERN OSTER HOUSE, CHARING CROSS ROAD 1897 PREFACE. In teaching the elements of chemistry to students beginning the study of Agricultural Science, I have felt the want of a text-book treating the subject experimentally throughout, proceeding at a fairly uniform rate, and dealing the formulae for alcohol and ethane I ^° H H H H H being H — C — C — 0 — H and H — C — 0 — H I I II H H H H respectively. The relations of aldehyde with alcohol are, however, much more clearly seen when we investigate it more closely and find that it easily combines with water or an equivalent, e.g. ammonia, molecule with molecule, without changing its properties. The formula may be H H I I H— C— C— O-i represented as H and it in- A Idehydes — Sugars 225 dicates that aldehyde may either play the part of the water compound or not. It also shows the relationship of the two bodies by the oxidation in the case of the aldehyde, of two hydrogen atoms attached to a single carbon atom into two hydroxy! groups. Pure aldehyde does not change in air, but when mixed with strong sulphuric acid it undergoes a curious change and its boiling- point suddenly rises : this is not accompanied by any change in percentage composition, but the molecular weight is found to be three times as great as it was before ; it is now represented by the formula (C 2 H 4 0) 3 . Such a change is called a polymerization, and (C 2 H 4 0) 3 or paraldehyde is said to be a polymer of aldehyde, C 2 H 4 0. If we cool the aldehyde to 0° C. before mixing with the strong sulphuric acid the aldehyde becomess olid metaldehyde, another polymer of high molecular weight. Again, take some fruit sugar, grape sugar, sugars. glucose, or honey, and boil it with (i) strong caustic potash solution, (ii) caustic potash and VOL. L Q 226 Chemistry copper sulphate solution, and (iii) ammoniacal silver nitrate solution. The solids in solution act like aldehyde and the substances are classed with aldehyde. The percentage composition and molecular weight of fruit sugar corresponds with the formula C 6 H 12 O c , which can be arranged to show its reactions thus : — H H H H H H I I I I I I H— C— C — C — C— C — C— O I I I I I 0 0 0 0 0 I I I I I H H H H H It is represented as an aldehyde. Take some cane sugar and test it with potash, potash and copper sulphate solutions, and ammoniacal silver nitrate solution as before ; no change is noticed, but if the cane sugar is first boiled with dilute sulphuric acid it is found to act like aldehyde after a short time. In fact it is changed by the addition of water, i.e. hydrolysis, into grape sugar, so that cane sugar is more complicated than grape sugar : this is shown by the percentage composition and A Idehydes — Sug ars 227 molecular weight which give us the formula C 12 H 22 O u = 2C 6 H 12 0 6 -H 2 0. This sugar also contains an aldehyde grouping. Take some starch and boil it for some time with dilute sulphuric acid. The starch solution becomes clear, and when neutralized with dilute caustic potash solution, tastes sweet. Boil some of either solution with strong- caustic potash solution, caustic potash and copper sulphate solutions, and ammoniacal silver nitrate solution. In each case the solution of starch acts like aldehyde, while the original starch like cane sugar does not readily change these solutions. Again, add some solution of iodine in potassium iodide to some boiled starch paste ; it is turned blue, a reaction which is characteristic of starch. Now add some of the iodine solution to the starch which has been boiled with dilute sulphuric acid ; no change takes place at all, or it may turn slightly red, showing that the starch disappears when the sugar appears. This reaction is not improbable from the Q 2 228 Chemistry formula of starch, which corresponds with (C 12 H 20 O 10 ) n , where n is possibly 3. Dextrin. Heat some starch in the oven for a short time ; it gains a sweet smell and becomes soluble in water. It now turns iodine solution brown, and does not change Fehling's solution, so that it is neither starch nor sugar. Boil some with dilute sulphuric acid ; it now gives the tests for sugar, and has been turned into sugar. This new body is called dextrin, and is represented by the formula C 12 H 20 O 1() . Other bodies of the same formula are very important in physiology, and will be referred to again when dealing with the subject of digestion. The starch, dextrin, cane sugar and grape sugar are representatives of four great divisions of the carbohydrates, the organic bodies in which the ratio of hydrogen to oxygen is the same as it is in water. The relations of the different carbohydrates, their solubilities, and the way in which they change into one another, are of the utmost importance in both plant and animal life ; their further study, however, must be deferred. A Idehydes — Sugars 229 These four classes of carbohydrates are named — Amyloses — starch, glycogen . . (Ci a H2oOio) n Dextrins C 12 H 2 oOio Saccharoses — cane, malt and milk sugars . . . . . C 12 H 2 20 n Glucoses — grape sugar . . . C 6 H 12 0 6 If we start with wood spirit (or methyl For ^f e de ' alcohol) instead of ordinary ethyl alcohol, and oxidize it by means of potassium bichromate and sulphuric acid, collecting the distillate as before, the product formed possesses all the properties of an aldehyde. This aldehyde is found on analysis to contain in its molecule the smallest possible number of carbon atoms, viz. one. It is called formaldehyde, and is repre- sented by CH 2 0, or HCHO, or— H / H / H— C or ^0 H— C — 0-i 1 O J J -H H corresponding with methyl alcohol, H— C— 0— H. 230 Chemistry It has the same percentage composition as grape sugar, C 6 H 12 0 6 , and it polymerizes very easily ; in fact there is little doubt that it is one of the forerunners of sugar in the life of green plants, which form it indirectly out of carbon dioxide taken from the air and water taken from the soil. CHAPTER XIX. ACIDS — ETHEREAL SALTS. Oxidation has proved as successful in the organic as in the inorganic world, so that we try its effect once more. Take a flask and fit it with a cork and long straight piece of glass tubing. Put some potassium bichromate and dilute sulphuric acid in the flask, and a small quantity of aldehyde. Keep the mixture simmering on a water bath ; the smell of aldehyde becomes fainter, and soon almost disappears. Now fit a bent tube and condenser, and distil. The liquid which condenses smells like vinegar, and turns blue litmus red. It is not sulphuric acid, as it does not give a precipitate with 232 Chemistry barium chloride, and it is not coloured, so is not an acid chromium compound. It will burn when boiling, and leaves no residue. It dissolves copper oxide, forming a blue solution, but when more copper oxide is added and the dry mixture heated, we find that carbon dioxide is formed, so the acid solution contains carbon. Neutralize the acid solution with caustic soda, carbonate of soda, or chalk, and evaporate to dryness. Place the dry solid in a retort and pour on it some strong sulphuric acid and heat the mixture gently ; in a short time a liquid distils over, which when condensed is found to have a strong smell of vinegar. It boils at 118° C, and when cooled freezes to a glassy solid at about 17° C. The freezing point is made much lower by the presence of only a small quantity of water, so that it is used as a test for the purity of the substance. It is strongly acid, and is neutralized by alkalies forming salts. Analysis shows that it has the percentage composition represented by the formula C 2 H 4 0.,, Acids — Ethereal Salts 233 and this is found to agree with the molecular weight of the body. It is called acetic acid. Comparing the formula C 2 H 4 0. 2 with those of aldehyde, from which it is formed directly, and alcohol, from which it is formed indirectly, we see that — C 2 H 4 0 2 = C 2 H 4 0 + O = C 2 H 6 0 + 20 - H 2 0 This when expressed in words is : — Each molecule of acetic acid contains one atom more of oxygen than a molecule of aldehyde, and two atoms of oxygen more and one molecule of water less than a molecule of the alcohol from which it is derived. Again, when any vegetable liquid containing alcohol and sugar is exposed to the air, it generally ferments and goes sour. If the sour liquid is neutralized with chalk, boiled, filtered and evaporated to dryness, and the residue distilled with sulphuric acid as above, a liquid distils off which is found to be identical with the acetic acid prepared by the oxidation of aldehyde. This acid is prepared on a large scale by the action of the vinegar plant on an 234 Chemistry extract of malt or any weak alcoholic liquid, and it is the vinegar of commerce. Pure acetic acid is prepared from vinegar as above. Again, when wood is distilled in retorts the distillate is found to be sour from acetic acid, and it is prepared in large quantities from wood by this method and sold as wood vinegar or pyroligneous acid. Many salts of acetic acid have been prepared, and those of sodium, calcium, copper, and iron are among the most useful. We have already prepared the first two. Dissolve some carbonate of copper in acetic acid and evaporate the solution, green crystals of an acetate of copper are formed. Precipitate a solution of copper sulphate by a mixture of sodium acetate and caustic soda solutions, a blue green precipitate at once falls, and is used as a pigment under the name of verdigris ; its composition shows less acetic acid than is required to form acetate of copper with the copper it contains, and so it is a basic salt resembling the basic phosphate of lime, basic slag. Acids — Ethereal Salts 235 Add some acetate of soda solution to ferric chloride solution, it turns red, but no precipitate is formed. Now boil the mixture, it turns brown and a precipitate forms, while the solution becomes colourless. Test the solution by means of potassium ferrocyanide, it is free from iron, so that the whole of the iron has been removed from the solution in the process. Collect the precipitate and boil some of it with sulphuric acid. The smell shows that it contains acetic acid, and the solution now gives the tests for iron ; as in the case of copper, the precipitate is a basic salt. This reaction is much used in agricultural chemistry to separate iron from phosphoric acid. We should like our formula of acetic acid to represent all these facts as far as pos- sible. When alkalies neutralize the acid, the salts they form contain the metal of the base in place of one atom of hydrogen. We shall naturally represent this peculiar property of one of the hydrogen atoms by giving it a special 236 Chemistry position in the molecule, thus H.C 2 H 3 0 2 may be supposed to represent the acid. Again, phosphorus pentachloride removes one oxygen and one hydrogen atom from the molecule and replaces them by one chlorine atom, giving the compound C 2 H 3 0C1, acetyl chloride, so that the acid contains one hydroxyl group, or may be represented by C 2 H 3 O.OH. But when caustic soda acts upon acetyl chloride, C 2 H 3 0C1, it replaces the chlorine atom by one oxygen and one sodium atom, so that it is likely that the hydrogen atom of the mole- cule which is replaced by sodium under the action of caustic soda is the same as that which is removed by phosphorus pentachloride with an oxygen atom in the form of the hydroxyl group. Again, chlorine acts upon the acid and replaces one, two, or three hydrogen atoms by chlorine without destroying its characteristic acid properties, and it leaves one hydrogen atom still, which can be replaced by sodium, and one hydroxyl group, which can be replaced Acids — Ethereal Salts 237 by chlorine when acted on by phosphorus pentachloride. This makes us believe that three of the hydrogen atoms are arranged in a similar manner in the molecule, while the fourth is differently situated. All these facts taken together with the mode of formation from aldehyde and alcohol by oxidation, show that we can best represent the reactions and properties of acetic acid by the H O formula CH 3 COOH or H-C-C-O-H. H We can in some cases better explain the relations of the acid, as in the case of aldehyde, by representing it as containing a carbon atom to which three hydroxyl groups are attached, though these split off water as a general rule. We are now in a position to compare the comparison of oxygen result of oxidizing a hydrocarbon, e.g. ethane, com P° und8 > with those of oxidizing an element, e.g. man- 2 3 8 Chemistry ganese. In the latter case we can compare the oxides or hydroxides. Products. Hydrocarbon. Element. Ethane. Manganese, I. Alcohol, a base. Manganous hydroxide, a base. II. Aldehyde, basic Manganese dioxide, a and acid. peroxide, basic and acid. III. Acetic acid, an Manganic acid, an acid. acid. In the case of many elements, more especially the metals, only the first effect is noticed, i.e. the production of a basic oxide ; in the case of others, more especially the non-metals, only the last effect, i.e. the production of an acid oxide ; but on the whole the effect of oxidation seems to be similar in both cases. Just as the alcohols combine with hydro- chloric and sulphuric acids, forming organic chlorides and sulphates, and as acetic acid combines with metallic bases, forming salts, so we might expect that acetic acid and alcohol would combine to form a wholly organic salt. Mix some alcohol with some acetic acid and Acids — Ethereal Salts 239 distil the mixture, little or no change takes place. Can we explain this ? Is it possible that we may have overlooked some action between the products? When an acid acts upon a base, a salt and water should be formed ; perhaps it would be as well in this case to try the effect of removing the water before giving up the attempt. Two methods are used for this purpose : (i) pass dry hydrochloric acid gas into the mixture of acid and alcohol, and (ii) heat the mixture with concentrated sulphuric acid ; the latter requires less apparatus, so we should try it first. Make a mixture of 20 cc. of alcohol and 20 cc. of acetic acid and run into an excess of concentrated sulphuric acid heated to 130° C. ; warm a little of the mixture in a test tube and smell it; a characteristic fragrant smell is noticed. Put the rest of the mixture (or more simply a mixture of sodium acetate, alcohol and sulphuric acid) into a flask fitted with a condenser and heat gently. A light mobile 240 Chemistry liquid distils off, with the characteristic smell noted above. This liquid is not very soluble in water, but is slowly decomposed by it into a mixture of alcohol and acetic acid ; acids and alkalies decompose it more quickly. The liquid is a salt of alcohol and acetic acid, ethyl acetate or acetic ester, and it is represented by the formula CH 3 — C^OCH' ^ * s one °^ the first representatives of a very large and important class of bodies, the ethereal salts or esters. A very large number of the essential oils contained in plants and of the fats and oils of plants and animals are decomposed by potash or soda into a mixture of an alcohol and a potassium or sodium salt of an organic acid. Many of these ethereal salts are of great importance in feeding, and we shall find that some of them are essential to the keeping up of health. We may now proceed to study some of the important organic acids. Formic acid. If we start with methyl alcohol or it* Acids — Ethereal Salts 241 aldehyde and oxidize it by the bichromate mixture, we get an acid with only one carbon atom per molecule, i.e. the acid with the smallest possible carbon content. This is formic acid, H— C^qjjj and its properties are very similar to those of acetic acid. It is the acid which is present in the bodies of red ants and in the hairs of the stinging nettle, but is not specially important at this stage. The water with which butter is washed *%$ He has a characteristic smell of butter, and when it is evaporated to dryness with a small quantity of chalk leaves a salt. This salt is more easily made by the action of one of the microbes of hay infusion upon starch. (Hay is stirred in water, strained off and the infusion boiled for five minutes. The extract is then mixed with starch, potassium phosphate, ammonium sulphate and chalk, and allowed to stand about ten days.) The salt when mixed with sulphuric acid and water gives a mixture of calcium sulphate and a new acid which burns VOL. I. R r 242 Chemistry when it is heated and a light applied to it. It has a composition agreeing with the presence of four carbon atoms in its molecule. It is called butyric acid, and is represented by CH — CH — CH 2 -COOH. The salts of butyric acid are called butyrates, and the most important is the butyrate of glycerine, which is characteristic of butter fat, of which it makes up about 8 per cent. Palmitic Boil some mutton or beef suet with caustic soda adds. and water. The fat dissolves, forming a frothy, viscous solution. Allow the solution to stand, and if it is sufficiently strong it sets to a hard soap. If it does not solidify, add some common salt to the solution, and curds of white soap, curd soap, separate out and rise to the top. (Soap is almost insoluble in salt water, so that sea water is not satisfactory to wash in.) The solution, as we already know, contains glycerine. Collect some of these curds of soap, or take some shavings of curd soap and boil them with water till they dissolve. When cool add hydrochloric acid or dilute sulphuric acid to Acids — Ethereal Salts 243 the solution. White flocks are again seen separating out, and in the solution nothing can be found except sodium chloride or sulphate. From this we should expect that the curds of soap are a sodium salt, since hydrochloric acid splits it into sodium chloride and another body ; it is so in this case. The flocks which separate out contain two acids, palmitic acid and stearic acid, which are represented by the formula C 15 H 31 COOH and C 17 H 35 COOH respectively. All the organic acids we have just been f^- d s t eries studying have properties which are similar to those of acetic acid. Some of the points of difference, e.g. boiling point, freezing or melting point, and generally the properties which we call physical properties, change gradually as we pass from each acid to the acid containing one more carbon atom in its molecule. In fact the acids we have in- vestigated form links in a complete chain or series, which includes many acids not de- scribed here, the acetic series of acids, all of B 2 244 < Chemistry which may be represented by the general formula CJI^ + iCOOH. The most charac- teristic point which concerns us at present is the fact that all these acids contain one hydrogen atom which is replaceable by metals, and that this hydrogen atom forms part of a characteristic group of atoms, represented by — COOHor— C^qjj and called the carboxyl group. This carboxyl group is always con- sidered to be characteristic of organic acids. We have just seen that when soap made * from fat is mixed with dilute sulphuric acid it is split up into flocks of fatty acid and a sulphate. Try the same experiment using lard instead of hard fat ; the flocks which appear are not so hard. When these flocks are made in large quantity, placed in canvas bags and pressed, a yellow oil is squeezed out, leaving hard white cakes of stearic and palmitic acids. This oil combines with soda to form a soap which is exactly like that prepared from soda and olive oil, and it is an acid, hence Acids 1 — Ethereal Salts 245 called oleic acid. On analysis it is found to be represented by the formula C 17 H Ti COOH, which only differs from the formula of stearic acid by containing two atoms of hydrogen fewer in the molecule. In fact the difference between the two acids, stearic and oleic acids, is similar to that between ethane and ethylene. The soda or potash soaps or salts of palmitic, fjw stearic and oleic acids are soluble in water, and the solutions make bubbles which last a long time without breaking, forming a lather when the solutions are shaken. When the solution has a special strength bubbles may be blown of very large size, by means of a glass tube or tobacco pipe., The best solution to use for this purpose is made by dissolving 1 gm.of oleate of soda (white Castile soap) in 40 cc. of cold water and 10 cc. of glycerine, adding a drop of ammonia ; it is allowed to stand a few days and filtered till clear. While the soda and potash soaps are soluble in water, the salts of other bases are not equally soluble. Make a solution of soap and 246 Chemistry pour it into a solution of calcium chloride. A white curdy precipitate is produced which is insoluble in water. No soap can be found in the solution, but only sodium chloride and un- changed calcium chloride. Add more of the solution of soap, it forms more precipitate, until the whole of the calcium is removed from the solution ; after this has taken place more soap solution makes a permanent lather. By means of a solution containing a known amount of soap we can even find out the quantity of lime salt which is in the water. The solution generally used is called Clark's solution. Dissolve 10 gm. of oleate of soda in 1 litre of a mixture of distilled water with 35 per cent, of methylated spirit. Measure out 70 cc. of water into a six-ounce stoppered bottle and add the solution from a burette, 1 cc. at a time, shaking at each addi- tion. When the solution makes a lather which does not break in five minutes, read off the number of cc. of soap solution used. Now since each cc. of the solution is made to A cids — Ethei'eal Salts 247 precipitate 1 mg. of chalk dissolved in carbonic acid, the number of cc. taken gives us the number of milligrams of lime salts (reckoned as chalk) dissolved in the 70 cc. of water taken. (It is usual to subtract 1 mg., since it requires 1 cc. of the soap solution to make a permanent lather with 70 cc. of pure distilled water.) The number of milligrams of chalk represents the hardness of the water in grains per gallon. Take some of the soap solution and shake it in a bottle with one or two cc. of oil ; the oil breaks up into globules, which become smaller, and finally form a cream or emulsion. In this way soap, or soda when used in washing greasy surfaces, removes the grease by making it into an emulsion. The same action will be found to be important in digestion. Fats contain the ethereal salts of glycerine, a Margarine. base, and palmitic, stearic and oleic acids. These fats have very similar properties, and we shall have to find out whether they can act in a similar way as foods later on. If fat is warmed to a temperature of 25° C. and then 248 Chemistry pressed in a filter press, a fat having nearly the same properties as butter fat is squeezed out ; this fat is used largely when flavoured with butter under the name of oleo -margarine or margarine. Just as we find alcohols which have more than one hydroxyl group in their molecules, so we have acids which we believe to contain more than one carboxyl group in their mole- cules, and these are very important in plant life ; one of the most characteristic is oxalic acid. Sorrel and rhubarb juice contain a sour or acid substance which may form crystals in the plant. Evaporate some of the juice and collect the crystals formed, called salt of sorrel (salt of lemon). Heat some of the crystals to red- ness. A residue is left which colours a flame lavender and fizzes when an acid is added, giving off carbon dioxide. This residue is potassium carbonate, and salt of lemon is a potassium salt. Dissolve some of the salt in water and add calcium chloride solution ; a Acids — Ethereal Salts 249 very fine white precipitate is formed, insoluble in water or dilute alkalies, but soluble in acids. Filter off the salt, suspend the crystals in water and then boil for a short time with dilute sulphuric acid. Filter the solution from calcium sulphate and evaporate it. Colourless crystals separate out. Heat a small quantity of these crystals, they give off thick fumes with a pun- gent smell. Dissolve some of the crystals in water and test with litmus solution, they are acid. The solution is neutralized by alkalies and forms salts. The crystals have the composition represented by — and are called oxalic acid. The salts are called oxalates. (Oxalic acid is generally made by fusing saw- dust with caustic potash and boiling the melt with water.) Neutralize some oxalic acid /OH C-OH \OH /OH C-OH \OH 250 Chemistry solution by ammonia solution, forming am- monium oxalate, and add it to a very weak solution of any calcium salt, a white precipitate of calcium oxalate is immediately produced ; tins is a very delicate test for the presence of small quantities of calcium salts. Place some crystals of oxalic acid in a test tube, pour some concentrated sulphuric acid upon them and heat. Apply a lighted taper from time to time. Soon a blue flame is seen burning at the mouth of the tube. The gas given off may be collected over caustic potash solution or milk of lime, which removes carbon dioxide formed at the same time. The gas will now burn, and the product turns lime water milky, showing the formation of carbon dioxide ; no water is formed. The gas burns to carbon dioxide and nothing else when mixed with oxygen, and is the combustible oxide of carbon, carbon monoxide, CO. The oxalates are poisonous in large quantities, and they form two series of simple salts in which either one or two hydrogen atoms are replaced by Acids — Ethereal Salts 251 the metal of the base. This is what we should expect from the presence of two carboxyl groups in the molecular formula of the acid. Another acid which gives rise to im- succinic acid, portant plant products is prepared by heating amber till it decomposes. Crystals separate out from the distillate, and are found to have the composition represented by the formula C t H 6 O t . The crystals are found to be acid, and are called succinic acid. We believe that the molecule of succinic acid contains two car- boxyl groups ( — COOH), one piece of evidence, as in the case of oxalic acid, being derived from the formation of two kinds of salts, the acid and normal succinates, in which one and two hydrogen atoms respectively are replaced by the metal of a base. Hence we arrange the formula thus — COOH I CH 2 I CH 2 I COOH 252 Chemistry Another organic acid is responsible for the souring of milk, ripening of cream and cheese, and for the souring of ensilage. This acid is produced by the life action of many fungi, of which the most active is Bacterum lactis, at a temperature of 34° — 35° C. Boil some sour milk or cheese with zinc oxide, filter the solution and evaporate it. Crusts of a crystal- line zinc salt are formed, which char when heated. Dissolve some of the crystals in water and pass in sulphuretted hydrogen gas till all the zinc is precipitated in the form of zinc sulphide. The solution tastes acid, turns litmus red, and when evaporated down becomes syrupy. The syrup is lactic acid, and when pure its composition is represented by the formula C 3 H 6 0 3 . (Lactic acid is readily formed by the oxidation of sugars by Bacterum lactis or by heating the sugars with caustic potash.) Lactic acid combines with soda and potash to form salts, the lactates, in which one hydrogen atom is replaced by the metal of the base, so that it contains one carboxyl group. Acids — Ethereal Salts 253 Phosphorus pentachloride replaces two oxy- gen and two hydrogen atoms by two chlorine atoms, so that the molecule of the acid con- tains two hydroxyl groups ; the formula which best represents the properties of the acid is — CH 3 I CH(OH) I COOH which contains one carboxyl and one alcoholic hydroxyl group. We should expect lactic acid to act as both an acid and a base ; it even forms a kind of salt by splitting off water from its acid and basic hydroxyl groups. (Several lactic acids are known, but their occurrence and properties hardly enter into the scope of this volume.) When the clear juice of unripe apples Or Malic acid, of berries of the mountain ash is evaporated to dryness, a colourless, sour mass is left. It is purified in exactly the same way as lactic acid. It has the composition represented by the formula 0 4 H 5 0 5 , and combines with 254 Chemistry potash and other bases to form salts. It is called malic acid, and forms two series of salts, the malates, in which one or two hydrogen atoms respectively are replaced by the metal of the base ; it contains two carboxyl groups, and is closely related to succinic acid. Malic acid can be made by substituting a hydrogen atom of succinic acid by chlorine and then replacing that chlorine atom by the hydroxyl group by the action of potash, just as in the formation of ethyl alcohol from ethyl chloride and ethane, so that malic acid contains a hydroxyl group which is alcoholic in character. These facts are summed up in the formula — COOH I CH(OH) I CH 2 I COOH acid aHc ^ ver y l ar 8 e number of ripe juicy fruits contain some sour or acid substances in their juice ; when the juice is evaporated to dryness, the acid substances are found mixed up with Acids — Ethereal Salts 255 the sugar of the fruit. When fruit juice is allowed to stand it begins to ferment, and as the sugar becomes converted into alcohol, crystals or a crust begin to separate from the solution. In the case of grape juice these crystals are collected and sent to market under the name of argol. The crystals are dissolved in water and re-crystallized, the clean crystals being called tartar, and when they are again re- crystallized they are known as cream of tartar. Take some cream of tartar crystals and heat them over a flame in a spoon or dish. They char, give off fumes smelling of burnt sugar,, and leave a solid residue which is found to be a mixture of potassium carbonate and charcoal ; thus cream of tartar contains potassium, and is probably the potassium salt of an organic acid. Make a solution of cream of tartar and add to it a solution of a lead salt, collect the precipitate, suspend it in water, pass in sulphuretted hydro- gen and evaporate the filtered solution. (Or boil the cream of tartar solution with calcium chloride solution, boil the precipitated calcium 256 Chemistry salt with dilute sulphuric acid and evaporate the filtered solution.) Colourless crystals form which turn litmus solution red and are known as tartaric acid. Dissolve some tartaric acid in water and pour it into solutions of caustic soda and of sodium carbonate. It neutralizes the solutions, decomposing the carbonate in the second case, and it forms salts. The acid is found to have the composition represented by C 4 H 6 0 6 . Make a solution of tartaric acid and neu- tralize some of it, say 25 cc, with caustic soda solution, running it in from a burette. Add to dpuble the quantity, i.e. 50 cc. of the tar- taric acid solution, the same quantity of the caustic soda solution. Evaporate both the solutions and compare the crystals formed, they are different ; one batch is neutral, the other acid to litmus, one gives a precipitate with a solution of a potassium salt, e.g. potassium chloride, the other does not. The acid salt can be made into the neutral salt by the addition of caustic soda. Evidently the two salts are different and tartaric acid is dibasic ; Acids — Ethereal Salts 257 we connect this as usual with the presence of two carboxyl groups in the molecule. Tartaric acid can be made from succinic by replacing two hydrogen atoms by two chlorine atoms, and these by two hydroxyl groups just as in the case of malic acid, so that it is repre- sented as containing two carboxyl and two alcoholic hydroxyl groups per molecule, i.e. — COOH CH(OH) CH(OH) I COOH This formula also points out the near re- lationship between succinic, malic, and tartaric acids. Tartaric acid is a constituent ol ripe fruits, so it is not poisonous ; advantage is taken of its acid properties for the production of carbon dioxide in the manufacture of effervescing drinks and baking powder. The carbonate generally used is sodium bicarbonate. Both tartrates of potash are used, cream of tar - VOL. I. S 258 Chemistry tar being the acid salt, KHC 4 H 4 0 6 , and normal potassium tartrate the neutral salt, KsCJE^Oe. Take solutions of ferric chloride and copper sulphate and add a solution of normal potassium tartrate to each. In both cases a precipitate is first formed which redissolves in excess of the tartrate solution. Now add caustic potash solution to the mixture ; instead of a precipitate being formed, only a change of colour is noticed. The presence of the tartrate appears to have prevented the precipitation of the hydroxide of the metal. We make use of this property in testing for sugar by the reduction of copper salts, as it enables us to keep an alkaline solution of copper hydroxide made up, i.e. Fehling's solution. Like other acids, tartaric acid combines with alcohols to form ethereal salts, many of which are present in wines and have characteristic flavours and scents. Again, the hydrogen atoms of the hydroxyl groups can be replaced by hydrocarbon radicles forming other character- istic ethereal salts. Acids — Ethereal Salts 259 Tartaric acid contains two alcoholic hydroxyl groups, so we should expect it to be easily oxidizable. Warm some of the ammo- niacal solution of silver nitrate with a few drops of tartaric acid solution. The acid is oxidized, the silver salt is reduced, and a silver mirror is formed ; this reaction is characteristic. Evaporate some filtered lemon juice or lime juice till it begins to crystallize. Colourless transparent crystals are formed, which are acid to litmus and are called citric acid. (The acid is made in a pure state by adding chalk to the juice till effervescence stops, boil- ing, filtering off the calcium citrate, washing it, and decomposing the salt by dilute sulphuric acid.) Heat some crystals of citric acid in a spoon or basin, they give off fumes which smell of burnt sugar but are more pungent. Dissolve some citric acid in water and neu- tralize 25 cc. of the solution with caustic soda solution run in from a burette. Add the same amount of the soda solution to 50 cc. and to 75 cc. s 2 260 Chemistry of the acid solution ; evaporate the solutions and compare the salts ; three different salts are formed, and citric acid contains three carboxyl groups. It contains four hydroxyl groups, so that its composition, which agrees with C 6 H 8 0 7 , is best represented by the formula — OH —CO OH j -X)OOH CH 2 — COOH Try the effect of solutions of citrates upon iron and copper salts ; like the tartrates, the citrates prevent the precipitation of the hydrox- ides by caustic potash. Just in the same way the citrates of lime are not precipitated by phosphoric acid in dilute solution, hence solutions of ammonium citrate are used in estimating phosphoric acid in phosphatic manures in order to keep the lime salts in solution ; the citrates do not prevent the precipitation of magnesium ammonium phos- phate. The salts of the last three acids, malic, tar- Acids — Ethereal Salts 261 taric and citric, or of some other similar acids, are present in the sap of all plants, and with their assistance the plant-roots are able to absorb from the soil many of the salts which make up the food of the plant ; they also keep many salts in solution during their passage from cell to eell throughout the plant. So much is this the case, that an artificial plant sap con- taining 1 per cent, of citric acid is at present one of the best reagents in use for estimating the readily soluble plant foods in the soil, and will be referred to in detail in the second part of this volume. A few acids derived from benzene require Benzoic L acid. to be mentioned. Many gums on being- warmed give off white fumes, and when gum benzoin is heated the fumes are found to be an acid, benzoic acid. This acid is derived from benzene by the substitution of a carboxyl group for one hydrogen atom, thus C 6 H 6 be- comes C 6 H 5 COOH. Benzoic acid forms a series of salts, the benzoates, which are interesting from their occurrence in herbivorous animals. 262 Chemistry salicylic If phenol is combined with caustic soda, acid. x 7 evaporated to dryness, powdered and heated to 200° C, and then carbon dioxide passed through the powder, combination takes place. The solid is dissolved in water, and hydro- chloric acid added. A white precipitate which has no smell is formed. This precipitate is not phenol, but a new acid, salicylic acid, which is best represented by the formula OH 0 6 H 4C qq- h -» A solution of salicylic acid prevents the growth of the fungoid germs of decay, and so is sometimes used as a preserva- tive for milk ; but it is poisonous, and its use is not now to be recommended, in many places it is illegal. Tannic acid* Among the large number of acids derived from benzene few are more important than the tannins, of which tannic acid is one of the most characteristic. Take some oak-galls, pulverize them finely and boil them with water. Pour some of the solution into ferric chloride solution, it turns black from the formation of ink. Pour some of the solu- Acids — Ethereal Salts 263 tion into some white of egg shaken up with water. A white precipitate or clot is at once formed, and it is characteristic of the tannins that they coagulate white of egg and similar bodies, and so alter the rate of digestion of these bodies. A similar action takes place in the process of tanning, when the tannin of the oak bark coagulates the materials of the skin. CHAPTER XX. NITROGENOUS ORGANIC BODIES — PROTEIDS. Though the study of the organic compounds containing nitrogen in their molecules is extremely fascinating and important, and though the problem of the chemistry of life is undoubtedly connected with the chemistry of organic nitrogen compounds, yet these bodies become rapidly complicated and require more time for their study than can generally be given. However, we must study a few characteristic compounds. Take some acetic acid in a basin and add lumps of solid ammonium carbonate till the acid is neutralized. Now pour the syrupy liquid, ammonium acetate, into a retort, with a Nitrogenous Organic Bodies 265 plain glass tube as a condenser, and lieat the retort. The liquid begins to boil, and water distils off. In a short time a smell of mice will be noticed, and when more than half has distilled over, the condensed liquid will be seen to solidify in the tube. Now change the receiving flask for a bottle, and collect the solid which continues to come over, and may be melted out of the tube. It is a soft transparent solid with a somewhat greasy feel, smelling of mice ; it melts at a low temperature and is soluble in water. Boil a little of the solution in water, the smell of mice disappears, and the solution contains ammonium acetate. The solid is formed from ammonium acetate with the loss of water, and reforms the acetate by the addition of water, and it is a representa- tive of a new class of bodies, the amides ; it is called acetamide, and when heated with lime gives off ammonia, so that it contains nitrogen. It is represented by the formula — CH 3 CO]SrH 2 =CH3COONH 4 -H 2 0 If we compare this formula with that of 266 Chemistry acetic acid, CH 3 COOH, we see that it may be considered as acetic acid in which the group of atoms NH 2 (i.e. NH 3 — H) replaces the hydroxyl group. This group, — NH 2 , is called the amido group, and acetamide is the amide of acetic acid. If we draw out the formulae — H H I | O H — C — C and H— C — C w I ^O-H | ^N^J H H H Acetic acid. Acetamide. we notice that the nitrogen atom is supposed to be in direct union with one carbon atom, so that we have the first characteristic of an organic nitrogen compound, viz. that it con- tains a nitrogen and a carbon atom in direct union. When acetamide is heated with phosphorus pentoxicle it gives up water and forms a new body, with the formula CH 3 — CN, which is even n simpler nitrogen compound than acetamide. It may be regarded as a compound of the methyl group, — CH 3 , with a new group of one carbon ami one nitrogen atom, called the cyanogen group. Nitrogenous Organic Bodies 267 Take a very small quantity of ferrocyanide ^ n °' deof of potassium and warm it very gently with dilute pota * slHm - sulphuric acid in a basin. Smell very care- fully, and a scent of laurel leaves or of bitter almonds which have been crushed with water will be noticed. This is due to the hydrogen com- pound of cyanogen, hydrocyanic or prussic acid, which is one of the most deadly poisons known as regards animal life. Hydrocyanic acid gives rise to a series of salts, the cyanides, also the series of ferrocyanides, ferricyanides, and suVphocyanides (thiocyanates). Heat a small quantity of potassium ferro- cyanide with strong sulphuric acid ; when cold add water and test for iron with potash, &c, as on p. 156. The salt is seen to contain iron ; now 7 test for potassium by the flame test, potassium is also present ; potassium ferrocyanide is in fact a compound salt of potassium, iron, and hydrocyanic acid, represented by the formula K 4 FeC 0 N 6 . Potassium ferrocyanide is not poisonous, nor does it answer to the usual tests for iron until it is decomposed ; it is curious 268 Chemistry that its properties should contrast so strongly with those of its constituents. Heat some potassium ferrocyanide in a basin ; it changes colour, and after heating answers to the tests for a simple cyanide ; dissolve in water, filter and evaporate the solution to dryness, potassium cyanide is left, KCN. Mix some potassium ferrocyanide with lead dioxide and heat the mixture over a flame. When cool warm the mass with alcohol, filter and collect the crystals which separate out. These crystals contain oxygen, and are repre- sented by the formula KOCN, potassium cyanate, which contains the group of atoms, — 0 — C — N, the cyanic group, which is remarkable for the ease with which it undergoes some kind of change within any molecule of which it forms part. Evaporate some urine to dryness and warm the residue with alcohol. Evaporate the solution till crystals separate out, collect and dry them, they are crystals of urea. Heat a few of the crystals of urea alone, they give off ammonia, and therefore contain nitrogen. Pour Nitrogenous Organic Bodies 269 some crystals into a solution of bleaching powder, a gas is given off, test it by a lighted taper and lime water, the gas is nitrogen ; this is another proof that urea contains nitrogen. When ammonium carbonate is heated to 130 — 140° C. it loses water, and urea may be extracted by alcohol from the product. The composition of urea agrees with the formula CON 2 H 4 , and this mode of formation, which suggests the formation of acetamide from acetate of ammonia, also suggests that urea may be re- presented as the amide of carbonic acid : thus — CO CO X OH X NH 2 Carbonic acid. Carbamide. The importance of urea is due to the fact that it is the principal form in which waste nitrogenous material is removed from the animal body, so that fresh stable or yard manure contains large quantities of urea. Urea is very easily converted into ammonium carbonate again under the influence of bacteria, 2 yo Chemistry and in that form readily passes into the air in the vapour of water which is evaporating from fermenting manure. Urea is also very easily con- verted into nitrogen by the action of microbes, when air is present ; hence the importance of excluding air and preventing evaporation from manure heaps if the urea is not to be wasted. Perhaps the most important date in the whole range of organic chemistry is the year 1828, in which Wohler succeeded for the first time in making or synthesizing an organic com- pound ; this compound was urea. When a solution of potassium cyanate is mixed with a solution of ammonium sulphate, ammonium cyanate and potassium sulphate are formed ; if the mixed solutions are evaporated and warmed with alcohol, crystals are obtained which have the same properties as urea crystals. Now ammonium cyanate, NCONH^, has the same composition and mole- cular weight as urea, CON.Hi, so that the atoms which build up the molecule of ammo- nium cyanate have most probably rearranged Nitrogenous Organic Bodies 2 7 1 themselves in such a way as to form the urea molecule, thus — NH a H / / forms C— 0 C— 0— NH 4 \ Such a change of position of the atoms compos- ing a molecule, involving a change of properties, is called an isomeric change, and ammonium cyanate is said to be isomeric with urea. This isomeric transformation, which led to the first synthesis of an organic body out of inorganic materials, also illustrates the point mentioned above, viz. the peculiar tendency of the atoms of the cyanic group to undergo a change of arrangement. A very near relation of urea found in 1 urine, and also in the excrements of birds and in guano, is uric acid, C 5 H 4 N 4 0 3 , but its composition cannot be considered here, It ferments to ammonium carbonate nearly as easily as urea, but only when moist, so that guano is liable to lose value when kept moist. 272 Chemistry A large number of bodies nearly related to uric acid are found in plant and animal struc- tures, more especially in animal flesh. These bodies are called extractives, and must be care- fully distinguished from the important class of protoids, which are much more complicated in composition. Another class of ammonia compounds is of the utmost importance, though rather beyond the scope of this volume, viz. the compounds of ammonia with alcohol radicles, the amines. If herring pickle is distilled with caustic potash, a characteristic fishy-smelling gas is given off. This gas combines with acids, and is found to be a mixture of ammonia compounds in which hydrogen atoms are replaced by methyl groups, thus — \H CH, and /CH 3 N-OH3 \OH 3 These compounds are called methylamine and trimethylamine respectively. Nitrogenous Organic Bodies 273 Metliylamine may thus be regarded as ammonia in which the methyl group replaces hydrogen, as methyl-amine, but it may also be regarded as methyl alcohol, in which the amido group, — NH 2 , replaces hydroxyl, — OH, forming amido-methane ; the latter point of view is sup- ported by its preparation from methyl chloride by the action of ammonia in alcoholic solution. Many bodies of this class are found in young plant tissues, and in any nitrogenous matter which has undergone fermentation, such as ensilage and decaying flesh. They are like the extractives as regards feeding purposes, and we shall have to note their peculiarities later on. We may notice two of the more important amido compounds. If we start with the lactic acid con- Leucine. taining six carbon atoms and replace the hydroxyl group by the amido group, we have the compound leucine, amido-caproic acid, to which we attach the formula — CH 3 — CH 2 — CH 2 — CH 2 — CH^ NIL * VOL. 1, T 2 74 Chemistry This body is contained in the young shoots of the G-ourds, and is a most important product of the digestion of proteid matter in the intestines. Asparagine. We have already noticed that malic acid occurs in young fruits to a large extent. When the juice of the shoots of vetches, peas, beans, or asparagus, or of the roots of scorzonera or mallow is evaporated, colourless crystals separate out. They are crystals of asparagine. When boiled with caustic potash they give off ammonia, and have the composition represented by — C 2 H 3 (N^^QQ-^Jp In other words, asparagine is an amide and an amine at the same time, amido-succinamic acid. Another important product of the digestion of proteid matter is the amido compound tyrosine, which is derived from benzene. Prouidt. As we have just seen, the chief nitrogenous products of the wear and tear of the flesh of animals are urea and uric acid. Of what substance is the flesh itself composed ? Nitrogenous Organic Bodies 275 Examine a piece of raw meat, it is not crystalline. Chop up some of the meat and pound it with a little common salt in a mortar. Add some water and filter through calico. The solution is not quite transparent, and becomes thick when boiled, forming a coagulum or clot ; this coagulum does not now dissolve in water. Try the same experi- ment with some white of egg, or albumen; it also coagulates when heated. These products of the living matter which coagulate when heated are called proteids or albuminoids, and they will be studied carefully later. Heat some proteid with quicklime, ammonia is given off, so that the proteid contains nitrogen. It also burns to carbon dioxide and water, and thus contains car- bon and hydrogen. Finally, when dried and then heated in a test tube it gives off water, showing that the proteid contains oxygen. Proteids are thus nitrogenous organic bodies which are compounds of carbon, hydrogen, oxygen, and nitrogen, but their molecules are so large that we do not yet know how they are built up. 276 Chemistry Having now traced the characteristic pro- perties of the common elements and their more important compounds, we are in a position to consider the practical application of our results. END OF VOL. I. INDEX ACETAMIDE, 265. Acetates, 234. Acetic acid, 233. ester, 240. series of acids, 243. Acetyl chloride, 236. Air, composition of, 12. a mixture, 26. Albuminoids, 275. Alcohol, ethyl, 213. methyl, 213. Aldehyde, 223. Alkali, 37. Allotropy, 35. Alloys, 97. Aluminium, 93. oxide of, 94. compounds, 176. Amido group, 266. Ammonia, 73. carbonate of, 146. chloride of, 80, 145. sulphate of, 73, 145. Ammonium, 144. salts, 143. Arsenic, 181. Asparagine, 274. Atom, 77. Atomic weight, 78. Base, 84. Basic oxide, 38. phosphate of lime, 130. Benzene, 207. Benzoic acid, 261. Bieaching, 48. powder, 151. Borax, 175. Bordeaux mixture, 102, 188. Butyric acid, 241. Calcium, 37, 100. chloride, 150. hydroxide, 100. sulphate, 147. sulphide, 149. Carbohydrates, 228. Carbolic acid, 207. Carbon, allotropic forms of, 35. bisulphide, 118. dioxide, 31. monoxide, 40, 250. Carbonic acid, 32. action on soils, 34. Carboxyl group, 244. Cement, 171. Chalk, 38. Charcoal, 27. Chemical change, 13. compound, 18. Chlorides, 45, 86. 278 hid ex Chlorine. 44. peroxide, 142. Citric acid, 259. Clay, 169. Coal gas, 196. Compound radicle, 144. Condy ; s fluid, 182. Conservation of matter, 4, 11. Copper, compounds of, 1ST. hydroxide. 102. Cyanogen group, 266. Dextrin. 228. Dialysis, 165. Dibasic acid. 114. Diffusion of gases, 63. Distillation. 15. Element, 23. Emulsion, 247. Equation, 87. Ethane, 203. Ether, 217. Ethyl acetate, 240. chloride, 203. Ethylene, 216. dichloride, 216. Eudiometer, 21. Fehling's solution. 222. Felspar, 170. Fermentation, alcoholic, 211. Ferric chloride, 154. hydroxide, 104. salts, tests for, 156. sulphate, 159. Ferrocyanide of potassium, 267. Ferrous chloride, 156. hydroxide, 104. salts, tests for, 156. sulphate, 157. Formaldehyde, 229. Formic acid, 240. Formula weights, 36. Formulae, 36. Fractional distillation, 206. Gas lime, 150. Glass, 168. Glycerine, 218. Gunpowder, 140. Gypsum. 14S. Hydrate, 37. Hydrocarbons, 204. Hydrochloric acid, 42. compounds, 49. Hydrogen, 17. properties of, 17. Hydrolysis, 226. Hydroxide, 37. 84. Iron salts, 103, 152. Lactic acid, 252. Law of Avogadro, 65. Boyle, 64. Charles, 65. Conservation of matter, 11. Constant proportions, 21. Diffusion of gases, 69. Substitution, 201. Yol umes, 51. Lead compounds, 178. Leucine, 273. Lime, 37. chloride of, 152. salts, 147. sulphate of, 147. Magnesium, 101. Malic acid, 253. Manganese compounds, 182. Margarine, 247. Marsh gas, 197. Mercury, oxide of, 7. salts of, 173. Metal, 94. Methane, 197. Index Methylamine, 272. Methyl chloride, 198. Molecular weight, 66. Molecules, 62. Mortar, 39. Neutralization, 79. Nitrate of soda, 52. Nitric acid, 53. test for, 158. Nitric oxide, 59. Nitrite of soda, 61. Nitrogen, 10. oxides of, 57. Oleic acid, 244. Oxalic acid, 2 48. Oxidation, 10. Oxide, 13. acid, 106. basic, 38. Oxygen, 8. Palmitic acid, 242. Paraffin series, 208. Permanganate of potash, 184. Peroxide, 179. Phosphates of lime, 128. soda, 126. Phosphoric acid, 126. Phosphorus, yellow, 121. red, 123. pentoxide, 125. Plaster of Paris, 148. Potash, 81. caustic, 84. Potassium, 83. chlorate, 142. chloride, 86, 141. cyanate, 268. cyanide, 268. nitrate, 137. Proteids, 274. Prnssic acid, 267. Quartz, 163. Quicklime, 36. Rust, 93. Salicylic acid, 262. Salt, 41. Saltpetre, 137. Salts, 87, 133. acid and normal, 113. Sand, 162. Silica, 164. Silicates, 167. Silicic acid, 166. Silicon, 164. Silver compounds, 190. Soap, 242, 245. Soda, caustic, 90. washing, 89. Sodium, 49. bicarbonate, 136. carbonate, 89, 134. chloride, 49. sulphites, 137. Solution, 24. saturated, 25. Spirit of wine, 211. Stearic acid, 242. Substitution, 199. Succinic acid, 251. Sugars, 225. Sulphides, 114. in soils, 117. solubility of, 116. Sulphite of soda, 107. Sulphur, 105. dioxide, 107. Sulphuretted hydrogen, 116. Sulphuric acid, 109. test for, 112. Sulphurous acid, 107. Superphosphate of lime, 129. Symbols, 35. Tannic acid, 262. 28o Index Tar, 206. Tartaric acid, 254. Tin compounds, 177. Titration of acids and alkalies, 85. chlorine by silver, 155, 191. iron by permanganate, 184. Turpentine, 209. Unsaturated compounds, 217. Urea, 268. Uric acid, 271. Vapour density, 66. determination of, 69. Water, composition by weight, 19. composition by volume, 21. distilled, 15. hardness of, 148. hardness of, determination of, 246. Wood spirit, 210. Zing salts, 172. Q-ILBEltT & RlVINGTON, LD. St, JOHN'S HOUSE, ClE KKEflT WELL, E.Q,