LIBRARY OF THE UNIVERSITY OF CALIFORNIA. Class The D. Van Nostrand Company intend this book to be sold to the Public at the advertised price, and supply it to the Trade on terms which will not allow of reduction. CHEMICAL REAGENTS THEIR PURITY AND TESTS A .NEW AND IMPROVED TEXT BASED ON AND REPLACING THE LATEST EDITION OF KRAUCH'S "DIE PRUFUNG DER CHEMISCHEN REAGENTIEN AUF REINHEIT " BY E. MERCK M AUTHORIZED TRANSLATION BY HENRY SCHENCK, A.B. (HARVARD) THE UNIVERSITY OF ^UFORN\ha NEW YORK D. VAN NOSTRAND COMPANY 23 MURRAY AND 27 WARREN STS. 1907 CD 77 Copyright, 1907 BY D. VAN NOSTRAND COMPANY The Plimpton Press Norwood Mass. U.S.A. DR. KRAUCH'S PREFACE As long ago as the early seventies I felt the need of a treatise on Chemical Reagents, and thought of compiling such a work. I was then an assistant in the chemical laboratory of the Government Agricultural Experiment Station at Munster, and in my chemical work there met with constant difficulties on account of the great variations in the chemicals which were graded as "C. P." "puriss," etc. It was my aim to fix uniform standards for such chemicals as are used in analytical work, such standards to define closely the degree of purity of the chemicals and yet to be possible of attainment in practice by the manufacturer. Not until 1888, however, did my work in this direction take the tangible form of a book, "Die Pruefung der Chemi- schen Reagentien auf Reinheit" A second revised and enlarged edition was published in 1891. In 1896 a third edition, carefully revised and still further enlarged, was pub- lished. Since that time a good many changes have taken place, so that my book again needed revision. As I was unable t6 undertake this work, Mr. E. Merck, appreciating the usefulness of such a work as mine, published in 1905 what might be considered its up-to-date revision. It is a source of gratification to me to see this work trans- lated and placed before my colleagues across the sea. Such changes and additions as the translator has made in order to adapt the book to their particular needs, have my approval. Darmstadt, February, 1907. DR. C. KRAUCH. iii 192831 TRANSLATOR'S PREFACE THE desire of American chemists to rid themselves of the misleading term " C.P.," and to get in its stead definite state- ments as to the exact degree of purity of their reagents or the exact limit of the impurities, impelled the American Chemical Society, in 1902, to create a Committee on Purity of Reagents. In 1906 this Committee advised against the publication of a book, because to use their own language " until further work is done and more data collected, such a work would be practically only a duplicate of the work of Krauch."* It is evident that the work of the Committee is being per- formed with most painstaking care, as, at the time of the last report, the Committee was working on " perfecting a method for the accurate colorimetric determination of traces of iron." * It is evident, too, that if the collection of data regarding other tests than those for iron is pursued with the same painstaking care, the complete report of the Committee will not be ready for publication for several years. My excuse for present- ing this translation now lies, therefore, in the hope that, until the work of the Committee appears, chemists will generally make acceptance of their purchases conditional upon their coming up to the specifications of purity prescribed by this translation. The additions mentioned by Dr. Krauch, in the preface he has kindly consented to write for this book, are limited to * See Journal of the American Chemical Society, Vol. XXVIII, No. 8, pp. 61 and 62. v vi TRANSLATOR'S PREFACE articles which are universally used here but do not seem to be so in Europe, and for which specifications could be found in authoritative American publications. They are Glacial Acetic Acid 99.5%, 36% Acetic Acid, Hydrochloric Acid of a specific gravity of 1.050, Nitric Acid with one of 1.40, Phosphoric Acid with one of 1.057, 10% Sulphuric Acid, 28% Ammonia Water, 95% Alcohol, and Glycerin of a 1.250 specific gravity. The slight changes obviously necessary in the text on account of these additions have been carefully made. THE TRANSLATOR. TRANSLATOR'S NOTE FOR the sake of brevity, expressions throughout the book are sometimes used without full qualification. The follow- ing is then to be their interpretation. Atomic Weights, Quantitative Calulations, etc., are based on the table of International Atomic Weights for 1906 in which = 16. Specific Gravities are given at + 15C, compared with water at + 4C. Unweighable Residue or words to that effect apply to residues weighing 0.0005 gin. or less. Solutions of chemicals to be tested are made from 1 gm. diluted to 20 cc. or proportionately. Volumetric Determinations can of course be made with other solutions than the potassium hydroxide and hydro- chloric acid solutions generally selected, provided they be equivalent. In such substitution, however, due regard must be given to the suitableness of the indicator. Nitric Acid has a specific gravity of 1.153. Hydrochloric Acid, one of 1.124. Ammonia Water, that of 0.96. The Marsh Apparatus should be set up with a 200 cc. generating flask. The tests presuppose the use of Jena or some equally re- sistant Glassware. vii OF THE UNIVERSITY OF CHEMICAL REAGENTS ACETONE (CH 3 )2CO. Mol. Wt. 58.Q4. A clear, colorless liquid, boiling at 56 to 57 C., with a specific gravity of 0.797. TESTS OF PURITY Residue on Evaporation. 25 cc. of acetone on evaporation should leave no weighable residue. Acids. Acetone should not redden blue litmus paper. Solubility in Water. Acetone should be miscible with an equal volume of water, yielding a clear liquid. Aldehydes. On heating 10 cc. of acetone with 5 cc. of ammoniacal silver nitrate solution for fifteen minutes on a steam-bath, the mixture must not acquire a brown color. Substances Oxidizable by Permanganate. On adding one drop of a 1 : 1000 solution of potassium permanganate to 10 cc. of acetone, and maintaining a temperature of 15 C., the pink color should not be entirely discharged within fifteen minutes. Water. On mixing equal volumes of acetone and petro- leum benzin (boiling-point 40 to 70 C.), two layers should not be formed. NOTE. Regarding the quantitative determination of acetone, see G. Lunge, Chem.-tech. Untersuch.-Meth., 4 ed., 3, 653 (1900). G. Kra- mer, Ber., 13, 1000 (1880); J. Chem. Soc., 38, 826 (1880). J. Messinger, Ber., 21, 3366 (1888); J. Chem. Soc., 56, 313 (1889). H. Strache, Mo- natsh. Chem., 12, 524 (1891) [or Ztschr. anal. Chem., 31, 573 (1892)]; J. Chem. Soc., 62, 546 (1892). F. Robineau and G. Rollin, Ztschr. anal. Chem., 33, 87 (1894); J. Chem. Soc., 64, II, 556 (1893). 1 2 CHEMICAL REAGENTS ACID ACETIC HC 2 H 3 O 2 . Mol. Wt. 60.03. I ACID ACETIC, 99-5% A clear, colorless liquid, with a strong odor; miscible in all proportions with water or alcohol, and containing at least 99.5 per cent of HC 2 H 3 2 . Specific gravity about 1.048 at 25 C. At about + 15.65 C. it solidifies. TESTS OF PURITY Non-volatile Matter. 10 cc. of acetic acid should leave no weighable residue on evaporation. Hydrochloric Acid. 5 cc. of acetic acid diluted with 50 cc. of water should afford no turbidity on the addition of 5 cc. of nitric acid followed by silver nitrate solution. Sulphuric Acid. On boiling a mixture of 10 cc. of acetic acid and 150 cc. of water, and then adding barium chloride solution, no precipitate of barium sulphate should form on standing twelve hours. Heavy Metals and Earths. (a) A mixture of 20 cc. of acetic acid and 100 cc. of water should not be affected by passing through it a current of hydrogen sulphide gas. (6) On diluting 10 cc. of acetic acid with 100 cc. of water and adding an excess of ammonia water, no green color should be developed on the addition of am- monium sulphide solution; nor should a turbidity or precipitate form on adding ammonium oxalate solution. Formic and Sulphurous Acids. 2 cc. of the acid are supersaturated with 8 to 10 cc. of ammonia water and a little silver nitrate solution added. No dark deposit should occur on boiling two minutes. CHEMICAL REAGENTS 3 Substances Reducing Permanganate. 2 cc. of the acid are diluted with 10 cc. of water, and 0.1 cc. of decinormal solution of potassium permanganate added. The pink color should not be entirely changed to brown within two hours. Other Empyreumatic Bodies. No smoky odor should be noticeable upon making 10 cc. of the acid alkaline with solu- tion of potassium hydroxide. Quantitative Determinations. Dilute 10 gm. of acetic acid with sufficient water to make 100 cc. Titrate 10 cc. of this solution with normal potassium hydroxide solution, using phenolphthalein as the indicator. 1 cc. of normal KOH = 0.06003 gm. HC 2 H 3 2 , log. 77837. The acetic acid content may also be ascertained from the specific gravity, if due note be taken of the fact that the specific gravities above 1.0553 represent in each case two liquids of different acetic acid content.* , II ACID ACETIC, GLACIAL, 96% A clear, colorless liquid with a pungent odor, solidifying at about + 10 C.; specific gravity 1.064, and boiling point 117 to 118 C. It contains at least 96 per cent of HC 2 H 3 2 . TESTS OF PURITY This acid should respond to the tests for non-volatile matter, hydrochloric acid, sulphuric acid, heavy metals, and quantitative determinations, as described under Acid Acetic 99.5 per cent. Its strength, however, is less. The following test also applies. Substances Reducing Permanganate. On adding 0.3 cc. * Compare G. Lunge, Chem.-tech. Untersuch.-Meth., 4 ed., 3, 681 (1900). Also U. S. Pharmacopoeia, VIII, p. 610 (1905). 4 CHEMICAL REAGENTS of decinormal potassium permanganate solution to a mixture of 5 cc. of acetic acid with 15 cc. of water, the red color should not disappear within fifteen minutes. Ill ACID ACETIC, 90% A colorless liquid having a specific gravity 1.071 and containing at least 90 per cent of HC 2 H 3 2 . TESTS OF PURITY The tests to be made are those given under Acid Acetic, Glacial, 96 per cent, observing the conditions there described. IV ACID ACETIC, 36% A clear, colorless liquid, specific gravity about 1.048, and containing about 36 per cent of HC 2 H 3 2 . TESTS OF PURITY The tests of purity and details of execution are the same as those given under Acid Acetic, Glacial, 96 per cent. But instead of 10 gm. (or cc.) of 96 per cent, use 25 gm. (or cc.) of the 36 per cent acid. V ACID ACETIC, DILUTED, 30% A colorless liquid having the specific gravity 1.041. The liquid contains about 30 per cent of HC 2 H 3 2 . TESTS OF PURITY The tests to be made are those given under Acid Acetic, Glacial, 96 per cent, observing the conditions there described. But instead of 10 gm. of the 96 per cent, use 30 gm. of the 30 per cent. CHEMICAL REAGENTS 5 (ACID) ACETIC ANHYDRIDE (CH 3 CO) 2 O. Mol. Wt. 102.05. A colorless liquid of pungent odor, boiling at 137 C. Specific gravity 1.08. On pouring acetic anhydride into water, it does not at first mix with the latter, but sinks to the bottom of the vessel. Gradually, however, it dissolves, forming acetic acid. TESTS OF PURITY Hydrochloric Acid. 1 cc. of acetic anhydride diluted with 50 cc. of water, and acidulated with 5 cc. of nitric acid, should give no reaction with silver nitrate solution. Non-volatile Matter. 10 cc. of acetic anhydride should leave no weighable residue on evaporation. Quantitative Determination. Dissolve 10 gm. of acetic anhydride in water and dilute to 100 cc. Titrate 10 cc. of this solution with normal potassium hydroxide solution, using phenolphthalein as indicator. It should require at least 19.3 cc. of the normal potassium hydroxide solution to develop the pink color. 1 cc. of normal KOH = 0.051025 gm. of (CH 3 -CO) 2 0, log. 70777. (ACID) BORIC ANHYDRIDE (BORON TRIOXIDE; BORIC ACID, FUSED) B 2 O 3 . Mol. Wt. 70.0. Brittle, vitreous, hygroscopic lumps used in silicate analy- sis, according to Jannasch.* TESTS OF PURITY Silica, Alkalies, etc. Add 50 cc. of methyl alcohol-hydro- * References : P. Jannasch andO. Heidenreich, Ztschr. anorgan. Chem., 12, 211 (1896) [or Ztschr. anal. Chem., 36, 382 (1897)]; J. Chem. Soc., 70, II, 576 (1896). 6 CHEMICAL REAGENTS chloric acid * to 5 gm. of the powdered boric anhydride in a weighed platinum dish, stir with a platinum wire until com- pletely dissolved, and evaporate the liquid over a small flame, the platinum dish being placed on wire gauze. If a residue remains, it is treated anew with 25 cc. of the methyl alcohol- hydrochloric acid, the liquid evaporated, and the dish and contents gently ignited. There must remain no weighable residue. ACID CARMINICj Purple-brown, amorphous masses, affording a dark red powder on trituration. Carminic acid is easily soluble in water and in alcohol, but is insoluble in benzene and chloro- form. It has no constant melting-point. TESTS OF PURITY Solubility. 1 gm. of carminic acid dissolves completely in 2 cc. of water. The addition of 20 cc. of 90 per cent alcohol to this solution should cause no appreciable precipi- tation. * The methyl alcohol-hydrochloric acid is prepared by saturating pure, anhydrous methyl alcohol, keeping the temperature low, with thoroughly dried hydrochloric acid gas. On standing for some time, however, the methyl alcohol-hydrochloric acid loses its original effectiveness. ^References: E. Schunck and L. Marchlewski, Ber., 27, 2979 (1894); J. Chem. Soc., 68, I, 67 (1895). C. Liebermann and H. Voswinckel, Ber., 30, 688 (1897); J. Chem. Soc., 72, I, 292 (1897). Ber., 30, 1731 (1897); J. Chem. Soc., 72, I, 539 (1897). C. Liebermann, P. Horing, and F. Wiedemann, Ber., 33, 149 (1900); J. Chem. Soc., 78, I, 236 (1900). J. Landau, Ber., 33, 2446 (1900); J. Chem. Soc., 78, I, 661 (1900). C. Liebermann and J. Landau, Ber., 34, 2153 (1901); J. Chem. Soc., 80, I, 545 (1901). C. Liebermann and S. Lindenbaum, Ber., 35, 2910 (1902); J. Chem. Soc., 82, I, 787 (1902). Regarding the use of carminic acid as a reagent see T. J. Bogolomow and N. J. Wassilieff, Pharm. Centrhl., 40, 120 (1899); E. Merck, Annual Report (on year 1898). CHEMICAL REAGENTS 7 If the carminic. acid is intended to be used as an indicator in acidimetry, it must first be tested as to its sensitiveness, as follows : Dissolve 1 gm. of the carminic acid in 100 cc. of water and add one drop of this solution to a solution of 5 gm. of ammonium chloride in 50 cc. of water. The addition to this latter solution of one drop of decinormal potassium hydroxide solution should cause a change in color from yellowish-red to violet-red. ACID CITRIC C 6 H 8 O 7 + H 2 O. Mol. Wt. 210.08. Colorless, odorless, rhombic prisms, efflorescing superficially in warm air. Citric acid is soluble in 0.75 part of cold and in 0.5 part of boiling water; in 1 part of 85 per cent alcohol, and in 50 parts of ether. TESTS OF PURITY Oxalic and Tartaric * Acids. On dissolving 1 gm. of citric acid in 2 cc. of water, and adding 10 drops of a 1:2 potas- sium acetate solution and 5 cc. of alcohol 85 per cent, no turbidity should be produced, nor should a crystalline deposit form within two hours. Tartaric Acid and Sugar. 1 gm. of citric acid and 10 cc. of sulphuric acid are ground together in a porcelain mortar previously rinsed with sulphuric acid. When this mixture is then heated in a test tube for an hour in a boiling water- bath it acquires at most a slight yellow color, but no brown color should develop. Sulphuric Acid. 20 cc. of the 1 : 10 aqueous solution must * Regarding the detection of tartaric acid in citric acid see Merck's Reagentien-Verzeichnis (1903), p. 170; A. I. Cohn, Tests and Reagents (1903), pp. 40, 51, 242. 8 CHEMICAL REAGENTS not be rendered turbid by the addition of barium chloride solution. Calcium. 20 cc. of the 1 : 10 aqueous solution must not be rendered turbid by the addition of ammonium oxalate solution. Lead.* A solution of 5 gm. of citric acid in 10 cc. of water, to which 12 cc. of ammonia water are added, should not acquire a dark color upon adding freshly made, saturated hydrogen sulphide water. Non-volatile Matter. 1 gm. of citric acid must leave no weighable residue on ignition. Quantitative Determination. On dissolving 1 gm. of citric acid in 30 cc. of water and titrating with normal potassium hydroxide solution, using phenolphthalein as indicator, not less than 14.2 cc. of the alkali solution should be required to develop the pink color. 1 cc. of normal KOH = 0.07002 gm. of C 6 H 8 7 + H 2 0, log. 84522. ACID GALLIC C 6 H 2 (OH) 3 (COOH) + H 2 0. Mol. Wt. 188.06. Colorless or slightly yellowish needles or prisms, which melt and slowly decompose at 220 C. Gallic acid dissolves in 130 parts of cold water, in 3 parts of boiling water, in 5 parts of 95 per cent alcohol, and in about 40 parts of ether. TESTS OF PURITY Solubility in Water. 1 gm. of gallic acid must dissolve completely in 20 cc. of water on heating. The solution must be colorless or only faintly yellowish. Water Content. On drying 1 gm. of gallic acid at 100 C. * Regarding the examination of citric acid for lead compounds see M. Bucket, Ztschr. anal. Chem. 32, 465 (1893); J. Chem. Soc., 64, II, 557 (1893). CHEMICAL REAGENTS 9 to constant weight, it should not lose more than 0.1 gm. in weight. Sulphuric Acid. On adding 1 cc. of hydrochloric acid and some barium chloride solution to a 1 : 50 aqueous solu- tion of gallic acid, a precipitate of barium sulphate must not form within an hour. Inorganic Matter. 1 gm. of gallic acid must leave no weighable residue on ignition. ACID HYDRIODIC HI. Mol. Wt. 127.97. ACID HYDRIODIC, SP. GR. 1.5 A clear, colorless liquid which, on exposure, to light and air, rapidly becomes yellow to brown, due to the separation of iodine. Specific gravity 1.5. The liquid contains about 43 per cent of HI. TESTS OF PURITY Non-volatile Matter. 5 gm. of hydriodic acid should leave no weighable residue on evaporation. Sulphuric Acid. On diluting 5 gm. of hydriodic acid with 50 cc. of water and adding barium chloride solution, no barium sulphate should precipitate on standing twelve hours. Heavy Metals and Earths. On diluting 10 gm. of hydriodic acid with 100 cc. of water and passing hydrogen sulphide gas into a portion of the solution, no colored precipitate should form; and, after adding an excess of ammonia water to another portion of the solution, neither ammonium sulphide nor ammonium oxalate solution should cause a visible change. 10 CHEMICAL REAGENTS Hydrochloric and Hydrobromic Acids. Dilute 1 gm. of hydriodic acid with 20 cc. of water, add an excess of silver nitrate solution followed by 30 cc. of ammonia water, shake well, and filter. On acidulating the filtrate with nitric acid, only a slight turbidity may develop, never a precipitate.* Quantitative Determination. Dilute 5 gm. of hydriodic acid with 50 cc. of water and titrate with normal potassium hydroxide solution, using methyl orange as indicator. At least 17 cc. of the normal alkali solution must be required to effect the change in color. 1 cc. of normal KOH = 0.12797 gm. of HI, log. 10710. II ACID HYDRIODIC, SP. GR. 1.70 A yellow or brownish liquid of specific gravity 1.70. The acid contains about 57 per cent of HI and is used for methoxyl determination, according to Zeisel. TESTS OF PURITY Tests for non-volatile impurities and sulphuric acid are made, observing the conditions given above. In titrating this acid, phenolphthalein is used as the indicator. ACID HYDROBROMIC HBr. Mol. Wt. 80.96. A clear, colorless, or faintly yellowish liquid, of specific gravity 1.38. It contains about 40 per cent of HBr. TESTS OF PURITY Non- volatile Matter. 10 gm. of hydrobromic acid on * A slight turbidity is permitted, because silver iodide is not absolutely insoluble in ammonia water. CHEMICAL REAGENTS 11 evaporation on the water-bath should leave no weighable residue. Sulphuric Acid. On diluting 5 gm. of hydrobromic acid with 50 cc. of water and adding barium chloride solution, a precipitate of barium sulphate should not form on standing twelve hours. Heavy Metals. (a) Dilute 10 gm. of hydrobromic acid with 10 cc. of water and overlay with hydrogen sulphide water; neither a coloration nor a yellow ring should form at the contact-surfaces of the two liquids on standing one hour. (6) Dilute 20 cc. of hydrobromic acid with 20 cc. of water, and add 30 cc. of ammonia water, followed by a few drops of ammonium sulphide and ammonium oxalate solutions; on standing two hours neither a brown coloration nor a precipitate should appear. (c) Boil 5 gm. of hydrobromic acid with 25 cc. of water and 2 drops of nitric acid. No reddish color should occur on the addition of potassium sulphocyanate solution. Hydrochloric Acid. 2 or 3 drops of hydrobromic acid are diluted with 4 cc. of water, and then mixed with 15 cc. of decinormal silver nitrate solution. To this mixture add 6 cc. of ammonium carbonate solution (1 part of ammonium carbonate, 1 part of ammonia water, and 3 parts of water), shake for five minutes, and filter. The filtrate acidulated with nitric acid may exhibit at most a faint turbidity. Hydriodic Acid. To a mixture of 5 drops of hydrobromic acid, 5 cc. of water, and 10 cc. of ammonia water, add one drop of silver nitrate solution. The mixture after being shaken must remain clear, or at most may develop a turbidity insufficient to destroy entirely its transparency. 12 CHEMICAL REAGENTS Besides the above test for hydriodic acid, the following may also be employed : On adding 1 drop of ferric chloride solution to 5 cc. of hydrobromic acid, and shaking with 5 cc. of chloroform, the latter should not acquire a violet color. Phosphorous and Phosphoric Acids. Heat 1 gm. of hydro- bromic acid with 1 cc. of nitric acid to boiling, allow to cool, and then add 4 cc. of ammonia water followed by 1 drop of magnesium sulphate solution. No precipitate should form even on standing two hours. Quantitative Determination. Dilute 5 gm. of hydrobromic acid with 50 cc. of water, and titrate with normal potassium hydroxide solution, using methyl orange as indicator. At least 24.6 cc. of the normal alkali solution should be required to effect the change in color. 1 cc. of normal KOH = 0.08096 gm. of HBr, log. 90827. ACID HYDROCHLORIC HC1. Mol. Wt. 36.45. I ACID HYDROCHLORIC. SP. GR. 1.19 (FUMING HYDROCHLORIC ACID) A clear, colorless liquid, fuming in the air, and of specific gravity 1.19. The liquid contains about 37 per cent of HC1. TESTS OF PURITY Sulphuric Acid. Evaporate 100 gm. of hydrochloric acid in a platinum dish to about 5 cc., dilute the residue with water, and add barium chloride solution. No precipitate of barium sulphate should form on standing twelve hours. Non- volatile Matter. 20 gm. of hydrochloric acid, when evaporated in a platinum dish on the water-bath, must leave no weighable residue. CHEMICAL REAGENTS 13 Chlorine.* Dilute 5 gm. of hydrochloric acid with 50 cc. of water and add zinc iodide-starch solution. The liquid must not develop a blue color within ten minutes. Sulphurous Acid. 50 cc. of water are colored blue by the addition of 1 drop of decinormal iodine solution and a few T drops of starch solution. Then add a mixture containing 5 gm. of the hydrochloric acid to be tested and 50 cc. of water. The liquid must not be decolorized after being shaken. Heavy Metals. - (a) Dilute 20 gm. of hydrochloric acid with 200 cc. of water, warm the liquid to about 70 C., and pass into it hydrogen sulphide gas for twenty minutes. No precipitate should form within two hours. (b) Dilute 20 gm. of hydrochloric acid with 200 cc. of Water, and add 50 cc. of ammonia water, followed by a few drops of ammonium sulphide solution. The mixture must not acquire a dark color, nor should a precipitate form. (c) Boil 5 gm. of hydrochloric acid with 20 cc. of water and 2 drops of nitric acid. After cooling, a reddish color should not occur on the addition of potassium sulphocyanate solution. Calcium. On diluting 20 cc. of hydrochloric acid with 20 cc. of water and adding 50 cc. of ammonia water, followed by a few cc. of ammonium oxalate solution, no precipitate should form on standing two hours. Arsenic. Add 0.1 gm. of potassium chlorate to 200 gm. of hydrochloric acid, and evaporate on the water-bath. A Marsh apparatus is started, using 20 gm. of arsenic-free, granulated zinc and dilute (1:5) sulphuric acid ; then the * Regarding the testing for chlorine, see also Kupfferschlager, Bull. Soc. chim. Paris, (3), 2, 134 (1889) [Ztschr. anal. Chem., 31, 201 (1892)]; J.Chem. Soc., 58, 289 (1890). 14 CHEMICAL REAGENTS residue from the above evaporation is washed into the gen- erating flask of the apparatus by the aid of dilute sulphuric acid. After the apparatus has been in action for one hour, there may be at most a very slight deposit in the reduction tube, but no distinctly visible arsenic mirror. Quantitative Determination. The strength of the acid may be most simply ascertained from the specific gravity.* On diluting 3 gm. of hydrochloric acid with 50 cc. of water, and titrating with normal potassium hydroxide solution, using methyl orange as indicator, not less than 30.5 cc. of the normal alkali should be required to effect the color change. 1 cc. of normal KOH = 0.036458 gm. of HC1, log. 56179. II ACID HYDROCHLORIC, SP. GR. 1.124 (DILUTED HYDROCHLORIC ACID) A clear, colorless liquid, of specific gravity 1.124, and containing 25 per cent of HC1. TESTS OF PURITY i The tests to be made are those given under Fuming Hy- drochloric Acid. But, instead of using 10 gm. of fuming acid, use 15 gm. of the acid of sp. gr. 1.124. Quantitative Determination. Dilute 5 gm. of the acid with 50 cc. of water, and titrate with normal potassium hydroxide solution, using methyl orange as indicator. At least 34.3 cc. of the normal alkali should be required for neutralization. * See the table by Lunge and Marchlewski, in Lunge's Chem.-techn. Untersuch.-Meth., 5 ed., 1, 419 (1904); U. S. Pharmacopoeia, VIII, p. 612 (1905). Compare J. Soc. Chem. Ind., 24, 789 (1905). CHEMICAL REAGENTS 15 III ACID HYDROCHLORIC, SP. GR. 1.050 A clear, colorless liquid, of specific gravity about 1.050, and containing about 10 per cent of HC1. TESTS OF PURITY The tests to be made are those given under Fuming Hy- drochloric Acid. But, instead of using 10 gm. of the fuming acid, use 35 gm. of the 10 per cent acid. ACID HYDROFLUORIC HF. Mol. Wt. 20. A colorless, or almost colorless, liquid, containing 38 to 40 per cent of HF. It fumes in the air. TESTS OF PURITY In these tests use platinum containers as much as possible. Non-volatile Matter. 20 gm. of hydrofluoric acid evapo- rated in a platinum dish, and gently ignited, should leave a residue weighing not more than 0.001 gm. Sulphuric Acid. Evaporate 2 gm. of hydrofluoric acid in a platinum dish on the water-bath, take up the residue with 10 cc. of water, and to this solution add a few drops of nitric acid and some barium nitrate solution. An immediate tur- bidity must not occur; and even after some time the liquid should exhibit, at most, a slight opalescence. Calcium. Dilute 5 gm. of hydrofluoric acid with 50 cc. of water and add ammonia water in excess, followed by ammo- nium oxalate solution. An immediate turbidity should not occur. Magnesium. Dilute 5 gm. of hydrofluoric acid with 50 cc. of water, and add ammonia water until the liquid has an 16 CHEMICAL REAGENTS alkaline reaction; on now adding ammonium phosphate solu- tion, no precipitate should form on standing three hours. Heavy Metals. - (a) Dilute 10 gm. of hydrofluoric acid with 40 cc. of water, warm the liquid, and saturate with hydrogen sul- phide gas. Neither a yellow nor a dark-colored precipitate should form. (6) Dilute 5 gm. of hydrofluoric acid with 50 cc. of water, make the solution alkaline with ammonia water, and add ammonium sulphide solution. A green coloration must not develop, nor should a precipitate form. Hydrochloric Acid. Dilute 2 gm. of hydrofluoric acid with 50 cc. of water and add a few drops of nitric acid and silver nitrate solution. The liquid may exhibit, at most, a faint opalescence. Hydrosilicofluoric Acid. On diluting 5 gm. of hydrofluoric acid with 20 cc. of water and adding 2 cc. of a cold, saturated potassium chloride solution, the further addition of 40 cc. of 85 per cent alcohol should cause no turbidity or precipitate. Quantitative Determination. Dilute 2 gm. of hydrofluoric acid with 50 cc. of water and titrate with normal potassium hydroxide solution, using phenolphthalein as indicator. 1 cc. of normal KOH = 0.020 gm. of HF, log. 30103. NOTE. Regarding the titration of hydrofluoric acid, see Katz, Chem. Ztg., 28, 356, 387 (1904); J. Chem. Soc., 86, II, 442 (1904). ACID HYDROSILICOFLUORIC (FLUOSILICIC OR SILICOFLUORIC ACID) H 2 SiF 6 . Mol. Wt. 144.41. A clear, colorless liquid having a specific gravity of about 1.06. This specific gravity corresponds to a content of 7.5 per cent of H 2 SiF 6 . CHEMICAL REAGENTS 17 TESTS OF PURITY Non- volatile Matter. 5 gm. of hydrosilicofluoric acid evap- orated in a platinum dish should leave no weighable residue. Heavy Metals. Dilute 5 gm. of hydrosilicofluoric acid with 10 cc. of water, add a few drops of hydrochloric acid and 10 cc. of hydrogen sulphide water. No visible change should take place. Sulphuric Acid. On diluting 5 gm. of hydrosilicofluoric acid with 10 cc. of water and adding a solution of barium-free strontium nitrate, no precipitate should form, even on stand- ing twelve hours. NOTE. Regarding the determination of hydrosilicofluoric acid, see Katz, Chem. Ztg., 28, 356, 387 (1904); J. Chem. Soc., 86, II, 442 (1904). ACID IODIC HIO 3 . Mol. Wt. 175.97. * Colorless, rhombic crystals, or white, crystalline powder, easily soluble (1 : 1) in water, but difficultly soluble in alcohol. The aqueous solution first reddens blue litmus paper and then bleaches it. TESTS OF PURITY Non- volatile Matter. On heating 2 gm. of iodic acid no weighable residue should remain. Solubility. 1 gm. of iodic acid should dissolve completely in 1 cc. of water, and yield a colorless solution. Quantitative Determination. Dissolve 1 gm. of iodic acid in water and dilute to 100 cc. Dilute 10 cc. of this solution with 50 cc. of water, and add 2 gm. of potassium iodide and 5 cc. of dilute sulphuric acid. Titrate the liberated iodine with decinormal sodium thiosulphate solution, using starch solution as indicator. 1 cc. of decinormal Na 2 S 2 3 = 0.002933 gm. of HI0 3 , log. 46731. 18 CHEMICAL REAGENTS (ACID) IODIC ANHYDRIDE (IODINE PENTOXIDE) I 2 O 5 . Mol. Wt. 333.94. A white, crystalline powder, soluble in water with the formation of the hydrated acid, HI0 3 , but insoluble in abso- lute alcohol, ether, and carbon disulphide. TESTS OF PURITY The tests to be made are those given under lodic Acid. 1 cc. of decinormal Na 2 S 2 3 = 0.00278283 gm. of I 2 5 , log. 4448. ACID MOLYBDIC H 2 MoO 4 . Mol. Wt.. 162.01. A white or slightly yellowish powder, containing about 85 per cent of Mo0 3 . TESTS OF PURITY Solubility in Ammonia Water ; Heavy Metals. 2 gm. of molybdic acid should completely dissolve in a mixture of 10 cc. of water and 5 cc. of ammonia water (sp. gr. 0.91), yielding a clear solution. On the addition of hydrogen sulphide water to this liquid it acquires a slight yellow color; a green color or a precipitate should not, however, develop. Phosphoric Acid. Quantitative Determination. As de- tailed under (Acid) Molybdic Anhydride, below. (ACID) MOLYBDIC ANHYDRIDE (MOLYBDIC ACID, 100%) MoO 3 . Mol. Wt. 144. A slightly yellowish powder, often exhibiting a faintly bluish tint, due to the presence of other oxides of molybde- num. The preparation contains about 100 per cent of Mo0 3 , and is free from ammonia and nitric acid. CHEMICAL REAGENTS 19 TESTS OF PURITY Alkalies. On heating 1 gm. of molybdic anhydride in a test tube, the particles adhering to the heated portion begin to fuse at a red heat, while at the upper, cooler portion of the tube a crystalline formation of sublimed anhydride may be observed. If the molybdic anhydride is contaminated with salts of the alkalies, the whole melts to a dark-colored mass. In such case the melting-point is low. Ammonium Salts. On boiling 1 gm. of molybdic anhy- dride with sodium hydroxide solution, there must be no liberation of ammonia (to be ascertained by means of moist- ened litmus paper). Solubility in Ammonia Water ; Heavy Metals. 2 gm. of molybdic anhydride, when gently heated with a mixture of 10 cc. of water and 5 cc. of ammonia water (sp. gr. 0.91), should entirely dissolve, yielding a clear solution. The solu- tion acquires a slight yellow color on adding hydrogen sulphide water. This color must not change within ten minutes nor should a precipitate form. Phosphoric Acid. Dissolve 10 gm. of molybdic anhydride in 25 cc. of water and 15 cc. of ammonia water (sp. gr. 0.91). The solution, mixed with 150 cc. of nitric acid, and allowed to stand for two hours at a temperature of about 40 C., must not contain a yellow precipitate. Nitric Acid. Shake 1 gm. of molybdic anhydride with 10 cc. of water, and add a small crystal of sodium chloride, followed by one drop of a 1 : 1000 solution of indigo; the blue color of the solution must not disappear on adding 10 cc. of concentrated sulphuric acid. Quantitative Determination. Dissolve 0.5 gm. of molybdic anhydride in a mixture of 50 cc. of water and 1 cc. of am- monia water (sp. gr. 0.91), with the aid of a gentle heat. Acidulate the solution with 5 cc. of acetic acid (sp. gr. 1.041), 20 CHEMICAL REAGENTS dilute with 200 cc. of water, heat to boiling, then add a solution of 1.5 gm. crystallized lead acetate in 20 cc. of water. Boil for several minutes with constant stirring, whereby the precipitate, at first milky, is rendered granular and easy to filter. Collect the precipitate on a filter, pre- viously dried at 100 C. and weighed, and wash it with boiling water until the washings cease to afford a reaction with hydrogen sulphide water. Dry the precipitate to constant weight at 100 C. and then ignite a portion of it. The ignited residue has the composition PbMo0 4 . PbMo0 4 X 0.39247 = Mo0 3 , log. 59380. ACID NAPHTHYLAMINESULPHONIC (ALPHANAPHTHYLAMINESULPHONIC ACID; NAPHTHIONIC ACID) C,oH.(NH2)(SOsH)l: 4 + iH 2 O. Mol. Wt. 232.18. A white powder, or small, lustrous, colorless needles (when crystallized from hot water), which carbonize but do not melt on being heated. Naphthylaminesulphonic acid is soluble in about 4000 parts of cold water, more readily in hot water, scarcely soluble in alcohol, and insoluble in ether. The solution in ammonia water exhibits a violet fluorescence. NOTE. Regarding the use of naphthylaminesulphonic acid for the detection and colorimetric determination of small quantities of nitrous acid, see E. Riegler, Ztschr. anal. Chem., 35, 677 (1896) [or Merck's Rea- gentien-Verzeichnis (1903), p. 120]; J. Chem. Soc., 72, II, 230(1897). E. Riegler, Ztschr. anal Chem., 36, 306 (1897); J. Chem. Soc., 72, II, 385 (1897). ACID NITRIC HNO 3 . Mol. Wt. 63.04. I ACID NITRIC, SP. GR. 1.40 A clear, colorless liquid, specific gravity 1.40 to 1.42, and containing about 68 per cent by weight of HN0 3 . X X C -ALIFOJ3 CHEMICAL REAGENTS 21 TESTS OF PURITY Non- volatile Matter. 4 cc. of nitric acid on evaporation should leave no weighable residue. Sulphuric Acid. Dilute 4 cc. of nitric acid with 90 cc. of water, and add barium chloride solution. No precipitate of barium sulphate should form on standing twelve hours. Hydrogen-Halogen Acids. 4 cc. of nitric acid diluted with 90 cc. of water must not appear changed on the addition of silver nitrate solution. Heavy Metals, and Earths. Dilute 8 cc. of nitric acid with 80 cc. of water, and render slightly alkaline with am- monia water. On adding a few drops of ammonium sul- phide and ammonium oxalate solutions, neither a dark color nor a turbidity should result. lodic Acid and Iodine. On diluting 2 cc. of nitric acid with 10 cc. of water, adding a small piece of metallic zinc, and shaking with a small quantity of chloroform, the chloro- form should not be colored violet. Quantitative Determination. Dilute 2 gm. of nitric acid with 50 cc. of water and titrate with normal potassium hydroxide solution, using methyl orange as indicator. 1 cc. of normal KOH = 0.06304 gm. of HN0 3 , log. 79962. II ACID NITRIC, SP. GR. 1.30 A clear, colorless liquid, of specific gravity 1.30, and con- taining about 47 per cent of HN0 3 . TESTS OF PURITY The tests to be made are those given under Acid Nitric sp. gr. 1.40, observing the conditions there described. But in- stead of 4 cc. of the acid sp. gr. 1.40, 7.5 cc. of. the acid sp. gr. 1.30 are to be used. 22 CHEMICAL REAGENTS III ACID NITRIC, SP. GR. 1.20 A clear, colorless liquid, of specific gravity 1.20, and con- taining about 33 per cent of HN0 3 . TESTS OF PURITY The tests to be made are those given under Acid Nitric sp. gr. 1.40, observing the conditions there described. But, instead of 4 cc. of acid sp. gr. 1.40, 10 cc. of acid sp. gr. 1.20 are to be used. IV ACID NITRIC, SP. GR. 1.153 A clear, colorless liquid, of specific gravity 1.153, and containing about 25 per cent of HN0 3 . TESTS OF PURITY The tests to be made are those given under Acid Nitric sp. gr. 1.40, observing the conditions there described. But instead of 4 cc. of acid sp. gr. 1.40, 13 cc. of acid sp. gr. 1.153 are to be used. ACID NITRIC, CRUDE, SP. GR. 1.38 A clear, colorless, or yellowish liquid of specific gravity 1.380-1.40, and containing at least 61 per cent of HN0 3 . TESTS OF PURITY Non- volatile Matter. 5 cc. of crude nitric acid on evapo- ration should leave no weighable residue. ACID NITRIC, FUMING, SP. GR. 1.486 A yellow, or reddish-yellow, clear liquid of specific gravity 1.486-1.500, and containing at least 86 per cent of nitric acid, HN0 3 . CHEMICAL REAGENTS 23 TESTS OF PURITY The tests to be made are those given under Acid Nitric sp. gr. 1.40. But for 4 cc. of acid sp. gr. 1.40, use 5 cc. of fuming nitric acid. ACID OXALIC H 2 C 2 O 4 + 2H 2 O. Mol. Wt. 126.04. Colorless, odorless, prismatic crystals, free from efflores- cence. Crystallized oxalic acid is soluble in 10 parts of cold, and in about 3 parts of boiling, water, in 2.5 parts of alcohol, and in about 100 parts of ether. On heating the hydrated oxalic acid in a capillary tube, it liquefies at 98 C. in its water of crystallization. On being heated to 70 C., the hydrated acid is rendered anhydrous, which latter sublimes at about 100 C. and melts at 187 C. This preparation must contain 99.8-100 per cent of the hydrated acid, H 2 C 2 4 + 2H 2 0. TESTS OF PURITY Ash. 3 gm. of oxalic acid, after being dried and then ignited in a platinum crucible, should leave no weighable residue. Sulphuric Acid. Dissolve 5 gm. of oxalic acid in 100 cc. of water, and add 1 cc. of hydrochloric acid and 1 cc. of barium chloride solution. No precipitate of barium sulphate should form on standing twelve hours. Chlorides. Dissolve 5 gm. of oxalic acid in 50 cc. of water, add 15 cc. of nitric acid and a few drops of silver nitrate solution. The solution may exhibit at most a slight opalescent turbidity. Heavy Metals. The 1 : 10 aqueous solution must be per- fectly clear, and on adding hydrogen sulphide water to 30 cc. of it, no reaction should be observed. On now adding 24 CHEMICAL REAGENTS ammonia water to this liquid until alkaline, neither a green nor a brown coloration should develop, nor should a precipitate form. Ammonium Compounds. (a) The solution of 5 gm. of crystallized oxalic acid in 30 cc. of sodium hydroxide solution on being boiled should not evolve ammonia (to be ascertained by means of moistened litmus paper). (6) On dissolving 2.5 gm. of oxalic acid and 5 gm. of potassium hydroxide in 30 cc. of water, and adding to the solution about 15 drops of Nessler's reagent, at most a slight yellow color should develop; never a brownish-red color. Nitric Acid. On overlaying 10 cc. of a solution of dipheny- lamine in concentrated sulphuric acid with 10 cc. of a 1 : 10 aqueous solution of oxalic acid, a blue zone should not form at the contact-surfaces of the two liquids. Quantitative Determinations. - (a) Acidimetrically : Dissolve about 6.3 gm. of crystallized oxalic acid in water, dilute to 500 cc., and titrate 25 cc. of the solution wjth one fifth normal potassium hydroxide solution, using phenolphthalein as indi- cator. Perform the titration at 60 C. 1 cc. of fifth normal KOH = 0.012605 gm. of H 2 C 2 4 + 2H 2 0, log. 10055. (b) By Oxidimetry : To 25 cc. of the aqueous solution (6.5 gm. of crystallized oxalic acid in water as above) add 6 to 8 cc. of concentrated sulphuric acid, heat to about 60 C., and titrate with decinormal potas- sium permanganate solution. 1 cc. of decinormal KMn0 4 = 0.0063024 gm. of H 2 C 2 4 + 2H 2 0, log. 79950. CHEMICAL REAGENTS 25 ACID OXALIC, SUBLIMED H 2 C 2 O 4 . Mol. Wt. 90.01. A white, crystalline, exceedingly hygroscopic powder, melting at 187 C. The preparation must contain at least 99.5 per cent of anhydrous oxalic acid, H 2 C 2 4 . TESTS OF PURITY Ash. 10 gm. of the oxalic acid on ignition should leave no weighable residue. Other Tests. The other tests to be made are those given under crystallized oxalic acid. 1 cc. of fifth normal KOH = 0.009001 gm. of H 2 C 2 4 , log. 95432. 1 cc. of decinormal KMn0 4 = 0.0045008 gm. of H 2 C 2 4 , log. 65329. NOTE. If it is desired to use sublimed oxalic acid for standardizing solutions for alkalimetric or oxidimetric determinations, it must be heated to dryness at a temperature of 60 to 70 C., in small quantities at a time. ACID PERCHLORIC HC1O 4 . Mol. Wt. 100.45. A colorless liquid of specific gravity 1.12, and containing about 20 per cent of HC10 4 . TESTS OF PURITY Non-volatile Matter. 10 gm. of perchloric acid when evaporated and ignited should leave no weighable residue. Sulphuric Acid. On diluting 5 cc. of perchloric acid with 100 cc. of water, and adding 1 cc. of hydrochloric acid, fol- lowed by barium chloride solution, a precipitate of barium sulphate should not form on standing twelve hours. Hydrochloric Acid. The mixture obtained by diluting 5 cc. of perchloric acid with 25 cc. of water and adding 3 cc. 26 CHEMICAL REAGENTS of nitric acid should not be rendered more than slightly turbid by silver nitrate solution. Barium. 10 cc. of perchloric acid diluted with 50 cc. of water must not become turbid within five minutes on adding dilute sulphuric acid. Heavy Metals. 10 cc. of perchloric acid diluted with 40 cc. of water must show no change on adding hydrogen sulphide water; and on adding to this solution 10 cc. of ammonia water, and a few drops of ammonium sulphide solution, a precipitate should not form, nor should the liquid acquire a green or brown color. ACID PHOSPHOMOLYBDIC 12MoO 3 H 3 PO 4 + xH 2 O. Yellow, lustrous crystals, easily and completely soluble in water, and yielding with the latter an acid solution. TESTS OF PURITY Solubility, Heavy Metals, and Earths. 1 gm. of phospho- molybdic acid should completely dissolve in 10 cc. of water. On adding to this solution two or three drops of ammonia water, a yellow precipitate forms, which completely redis- solves on the addition of 5 cc. of the ammonia water. On now adding to this solution ammonium sulphide and ammo- nium oxalate solutions, no visible change should take place. ACID PHOSPHORIC (Ortho.) H 3 PO 4 . Mo. Wt. 98.02. I ACID PHOSPHORIC, SP. GR. 1.7 A clear, colorless, odorless, syrupy liquid, of specific gravity 1.7, and containing about 85 per cent of H 3 P0 4 . CHEMICAL REAGENTS 27 TESTS OF PURITY Volatile Acids. Mix 30 cc. of the phosphoric acid with 50 cc. of water in a distilling flask. Distil * off 50 cc., and titrate the distillate with decinormal potassium hydroxide solution, using methyl orange as indicator. Not more than 0.1 cc. of the decinormal alkali solution should be required. Nitric Acid. 2 cc. of phosphoric acid mixed with 2 cc. of concentrated sulphuric acid, and overlaid with 1 cc. of a solution of ferrous sulphate, must not develop a colored zone. Hydrogen-Halogen Acids and Phosphorous Acid. 2 cc. of phosphoric acid diluted with 18 cc. of water should give no reaction With silver nitrate solution either in the cold or on warming. Sulphuric Acid. On adding barium chloride solution to 20 cc. of the diluted acid (1:10), no precipitate of barium sulphate should form on standing two or three hours. Metaphosphoric Acid. On dropping the acid diluted with 10 volumes of water into a dilute solution of albumen, no turbidity should ensue. Heavy Metals, Earths, Etc. - (a) Dilute the acid with 10 volumes of water, and to 20 cc. of the mixture add hydrogen sulphide water. There should be no visible change. (b) On adding 10 cc. of ammonia w r ater to 20 cc. of the above diluted acid, no precipitate should form on the further addition of either ammonium oxalate solution, or ammonium sulphide solution. (c) A mixture of 5 cc. of phosphoric acid with 20 cc. of absolute alcohol should remain perfectly clear. Substances Oxidizable by Permanganate. On adding 5 * In order to prevent spirting over of phosphoric acid, the flask should be provided with a Kjeldahl connecting bulb tube. The distillate must be tested with ammonium molybdate solution for phosphoric acid. 28 CHEMICAL REAGENTS drops of decinormal potassium permanganate solution to a mixture of 5 cc. of phosphoric acid and 5 cc. of diluted sul- phuric acid, and then heating for five minutes at 100 C., the red color of the liquid should not disappear. Arsenic. A Marsh apparatus is started using 20 gm. of arsenic-free, granulated zinc, and diluted (1:5) sulphuric acid. A mixture of 3 cc. of phosphoric acid with 20 cc. of water is then introduced in small quantities at a time, the evolution of hydrogen being maintained for about two hours. A deposit of arsenic should not be visible in the reduction tube within these two hours. Quantitative Determination. Dilute 1 gm. of phosphoric acid with 30 cc. of water, and titrate with normal potassium hydroxide, using phenolphthalein as indicator.* At least 17 cc. of normal alkali must be added to produce the red color. 1 cc. of normal KOH = 0.04901 gm. of H 3 P0 4 , log. 69028. II ACID PHOSPHORIC, SP. GR. 1.12 A clear, colorless, odorless liquid of specific gravity 1.12, and containing about 20 per cent of H 3 P0 4 . TESTS OF PURITY The tests to be made are those given under Acid Phos- phoric sp. gr. 1.7. But for 1 cc. of the phosphoric acid sp. gr. 1.7, use 4 cc. of the phosphoric acid sp. gr. 1.12. * Methyl orange may be used instead of phenolphthalein. In this case, however, 1 cc. of the normal KOH = 0.09802 gm. of H 3 PO 4 , log. 99131. When titrating with phenolphthalein, twice as many cubic centimeters of the alkali solution are required as when using methyl orange. CHEMICAL REAGENTS 29 III ACID PHOSPHORIC, SP. GR. 1.057 A clear, colorless, odorless liquid of specific gravity about 1.057, and containing about 10 per cent of H 3 P0 4 . TESTS OF PURITY The tests to be made are those given under Acid Phos- phoric sp. gr. 1.7. But for 1 cc. of the acid sp. gr. 1.7, use 10 cc. of the acid sp. gr. 1.057. (ACID) PHOSPHORIC ANHYDRIDE (PHOSPHORUS PENTOXIDE) P 2 O 5 . Mol. Wt. 142.00. A white, amorphous, odorless, bulky powder, which dis- solves in water with a hissing noise, forming metaphosphoric acid. Phosphoric anhydride completely sublimes on being heated. TEST OF PURITY Arsenous Acid. Introduce 1 gm. of phosphoric anhydride, in small portions at a time, into 20 cc. of water, and while warming the solution, pass into it a current of hydrogen sulphide gas. The liquid should not acquire a yellow color, nor should a yellow precipitate form. ACID PHOSPHORIC, META (GLACIAL PHOSPHORIC ACID) HPO 3 . Mol. Wt. 80.0. Colorless, transparent, vitreous pieces or sticks, deliquescent in moist air, and melting to a clear viscid liquid on being warmed. Metaphosphoric acid is very easily soluble in water. 30 CHEMICAL REAGENTS TESTS OF PURITY Nitric Acid. On adding 2 cc. of concentrated sulphuric acid to a solution of 1 gm. of metaphosphoric acid in 2 cc. of water, and overlaying the mixture with 1 cc. of a solution of ferrous sulphate, no colored zone should form. Sulphuric Acid. The solution of 1 gm. of metaphosphoric acid in 20 cc. of water must not immediately be rendered turbid on the addition of 5 cc. of hydrochloric acid, followed by barium chloride solution. Hydrogen-Halogen Acids. Add 5 cc. of nitric acid to a solution of 1 gm. of metaphosphoric acid in 20 cc. of water. On the further addition of silver nitrate solution the liquid should appear unchanged. Heavy Metals, Earths, Etc. (a) The solution of 1 gm. of metaphosphoric acid in 20 cc. of water must not be affected by hydrogen sulphide water. (6) On adding 5 cc. of ammonia water to a solution of 1 gm. of metaphosphoric acid in 20 cc. of water, no precipitate should form on adding ammonium oxalate and ammonium sulphide solutions. Arsenic. On adding 5 cc. of stannous chloride solution to a solution of 1 gm. of metaphosphoric acid in 1 cc. of water, the mixture should not darken on standing one hour. Substances Oxidizable by Permanganate. Dissolve 1 gm. of metaphosphoric acid in 10 cc. of water, add 5 cc. of 16 per cent sulphuric acid and 0.1 cc. of decinormal potassium permanganate solution; then heat 5 minutes at 100 C. The red color of the mixture should not disappear. ACID PHOSPHOTUNGSTIC (P 2 O 5 20WO S 11H 2 O) + 16H 2 O. Mol. Wt. 5268.43. Small, white, or slightly yellowish-green ' crystals, easily soluble in water, and free from ammonia and nitric acid. CHEMICAL REAGENTS 31 TESTS OF PURITY Nitrates. Dissolve 1 gm. of phosphotungstic acid in 10 cc. of water, add a granule of sodium chloride and 1 drop of indigo solution (1: 1000), followed by 10 cc. of concentrated sulphuric acid. The blue color of the mixture must not disappear within ten minutes. Ammonium Salts. On heating a solution of 1 gm. of phosphotungstic acid in 10 cc. of water, with 5 cc. of sodium hydroxide solution (sp. gr. 1.3), no ammonia should be evolved (to be ascertained by means of dampened litmus paper) . NOTE. Regarding a method for the quantitative analysis of phos- photungstic acid, see F. Kehrmann, Ber., 20, 1813 (1887); J. Chem. Soc., 52, 777 (1887). ACID PICRIC (PICRONITRIC ACID; TRINITROPHENOL) C 6 H 2 (OH)(NO 2 ) 3 . Mol. Wt. 229.14. Pale yellow, glistening crystals, melting at 122.5 C., soluble in about 90 parts of cold water and in about 30 parts of boiling water. The acid is readily soluble in alcohol, ether, and benzene. TESTS OF PURITY Resins ; Substances Insoluble in Water. 1 gm. of picric acid should dissolve completely and without turbidity in 100 cc. of water. On adding to the solution 1 or 2 drops of 16 per cent sulphuric acid, no precipitate should form on standing twelve hours. On subsequently filtering the liquid, no resin should remain on the filter. Picrates of Potassium, Sodium, and Ammonium.* 1 gm. of * Picric acid cannot be tested for ammonia by warming with sodium hydroxide solution, as under such conditions picric acid itself decomposes with the evolution of ammonia. 32 CHEMICAL REAGENTS picric acid must completely dissolve in 20 cc. of benzene, affording a clear solution. Oxalic -Acid. On adding calcium chloride solution to a solution of 1 gm. of picric acid in 100 cc. of water, a precipitate of calcium oxalate should not form within two hours. Free and Combined Sulphuric Acid. Evaporate a mixture of 2 gm. of picric acid and 10 cc. of nitric acid (sp. gr. 1.4) to dryness on the water-bath. Dissolve the residue in 100 cc. of boiling water with the addition of 5 cc. of nitric acid, allow to cool, then filter, and add barium nitrate solution to the filtrate. There should be no immediate turbidity. Inorganic Matter (Ash). 1 gm. of picric acid cautiously incinerated in an open platinum dish should not leave a residue weighing more than 0.001 gm. ACID ROSOLIC (CORALLIN) Brittle, amorphous, reddish-brown pieces, presenting a metallic reflection, and readily soluble in alcohol, but insoluble in water. Rosolic acid is used as an indicator in the form of a solution of 0.5 gm. of the acid in a mixture of 50 cc. of 85 per cent alcohol and 50 cc. of water. TESTS OF SENSITIVENESS Add two or three drops of the above rosolic acid solution to 100 cc. of distilled water. On adding to the solution 0.05 cc. of decinormal potassium hydroxide, the pale-yellow color of the water should change to a rose-red, and on the further addition of 0.05 cc. of decinormal hydrochloric acid, the original color should be restored. CHEMICAL REAGENTS 33 ACID SUCCINIC C 4 H 6 O 4 . Mol. Wt. 118.04. Colorless, monoclinic prisms, soluble in 20 parts of cold and about 2 parts of boiling water; in 10 parts of alcohol and in 80 parts of ether. Succinic acid melts at 182 C., and at 235 C. it boils with the evolution of white acrid fumes, while it undergoes decomposition to a large extent into water and succinic anhydride. TESTS OF PURITY Non-volatile Matter. 1 gm. of succinic acid heated in a platinum dish should volatilize and leave no weighable residue; nor should any charring occur. Oxalic Acid. The solution of 1 gm. of succinic acid in 20 cc. of water should not be affected by calcium chloride solution. Tartaric Acid and Sulphates. On adding potassium acetate and barium nitrate solutions to a solution of 1 gm. of succinic acid in 20 cc. of water, no precipitate should form on standing twelve hours. Chlorides. On adding 2 or 3 cc. of nitric acid to 20 cc. of the 1 : 20 aqueous solution of succinic acid, not more than a faint opalescent turbidity should develop on the addition of silver nitrate solution. Ammonium Salts. 1 gm. of succinic acid, on being heated with 10 cc. of sodium hydroxide solution (sp. gr. 1.3), should liberate no ammonia (to be ascertained with moist litmus paper). Heavy Metals. 1 gm. of succinic acid dissolved in 20 cc. of water should not be visibly changed by hydrogen sulphide water. Quantitative Determination. Dissolve 1 gm. of succinic 34 CHEMICAL REAGENTS acid in 50 cc. of water, and titrate with normal potassium hydroxide, using phenolphthalein as indicator. 1 cc. of normal KOH = 0.05902 gm. of C 4 H 6 4 , log. 77100. ACID SULPHANILIC C 6 H 4 (NH 2 )(SO 3 H)1: 4 + 2H 2 O. Mol. Wt. 209.18. Sulphanilic acid occurs in colorless, acicular, efflorescent crystals. It has no melting-point, but carbonizes on being heated to 280 to 300 C. The acid is difficultly soluble in cold water (about 150 parts), but more readily soluble in hot water; it is insoluble in alcohol, ether, and benzene. TESTS OF PURITY Inorganic Matter. 1 gm. of sulphanilic acid should leave no weighable residue on ignition. Sulphuric Acid (Aniline Sulphate). A solution of 1 gm. of sulphanilic acid in 25 cc. of boiling water should not change in appearance on adding a few drops of barium chloride solution. Hydrochloric Acid (Aniline Hydrochloride). On shaking 1 gm. of sulphanilic acid with 20 cc. of water and filtering, the filtrate should exhibit at most a faint opalescent tur- bidity on the addition of a few drops of nitric acid and silver nitrate solution. ACID SULPHURIC H 2 SO 4 . Mol. Wt. 98.07. I ACID SULPHURIC, SP. GR. 1.84 (CONCENTRATED SULPHURIC ACID) A clear, colorless, oily liquid of specific gravity 1.84, and containing 95 to 96 per cent of H 2 S0 4 . CHEMICAL REAGENTS 35 TESTS OF PURITY Non-volatile Matter. 10 cc. of sulphuric acid, on being evaporated and ignited, should leave no weighable residue. Nitric Acid. Dilute 1 cc. of sulphuric acid with 9 cc. of water, and overlay this liquid on 5 cc. of diphenylamine solution (see Diphenylamine, page 100). A blue zone should not form at the contact-surfaces of the two liquids. Selenium. On overlaying 2 cc. of sulphuric acid with 2 cc. of hydrochloric acid, in which a granule of sodium sulphite has been dissolved, a reddish zone must not form at the contact-surfaces of the two liquids; nor should a red precipitate form on warming. Substances Oxidizable by Permanganate. (Nitrous and Sulphurous Acids). Dilute 15 cc. of sulphuric acid with 60 cc. of water, and color the solution by adding 1 drop of decinormal potassium permanganate solution. The pink color should not disappear within three minutes. Hydrogen-Halogen Acids. 2 cc. of sulphuric acid diluted with 30 cc. of water should appear unchanged on adding a few drops of silver nitrate solution. Lead. On cautiously diluting 10 cc. of sulphuric acid with 50 cc. of 85 per cent alcohol, no turbidity should be observed; nor should a precipitate of lead sulphate form on standing two hours. Heavy Metals and Calcium. (a) Dilute 10 cc. of sulphuric acid with 50 cc. of water, and add ammonia water in excess. On now adding a few drops of ammonium sulphide and ammonium oxalate solutions, neither a green color nor a turbidity should occur. (6) On diluting 20 cc. of sulphuric acid with 100 cc. of water, and passing a current of hydrogen sulphide gas into the solution, no brown color should develop; 36 CHEMICAL REAGENTS nor, after the passage of the gas, should any brown flocks precipitate on long standing (Tin). Ammonium Salts. Dilute 2 cc. of sulphuric acid with 30 cc. of water, and add aqueous solution of potassium hydroxide (1 : 6) to alkalinity, followed by 10 to 15 drops of Nessler's reagent. At most a light-yellow precipitate may form, but in no case a brownish-red one. Arsenic.* A Marsh apparatus is set in operation, using 20 gm. of arsenic-free, granulated zinc, and arsenic-free, dilute sulphuric acid (1:5). As soon as the air has been expelled from the apparatus, heat the reduction tube to redness, and then introduce a cooled mixture of 10 cc. of the acid (sp. gr. 1.84) to be tested and 50 cc. of water. No deposit of arsenic should be visible in the reduction tube within half an hour. Quantitative Determination. The content of H 2 S0 4 is most readily ascertained by taking the specific gravity, and then referring to tables for the percentage. Consult the tables of Lunge, Isler, and Naef, Chem.-tech. Untersuch. - Meth., 5 ed., 1, 354 (1904); compare Watts' Diet, of Chem., 4, 621 (1894); also J. Soc. Chem. Ind., 24, 790 (1905). The acid content may also be ascertained by titration with normal potassium hydroxide solution, using methyl orange as indicator. 1 cc. of normal KOH = 0.049038 gm. of H 2 S0 4 , log. 69053. II ACID SULPHURIC, DILUTED 16% A colorless liquid of specific gravity 1.110 to 1.114, and containing 15.7 to 16.3 per cent of H 2 S0 4 . * Regarding the detection of arsenic in sulphuric acid, see Lunge, Chem.-tech. Untersuch. -Meth., 5 ed., 1, 367 (1904); Detection and Deter- mination of Arsenic. Reprint from J. Soc. Chem. Ind., 1901. CHEMICAL REAGENTS 37 TESTS OF PURITY The tests to be made are those given under Acid Sulphuric sp. gr. 1.84. But for 1 cc. of the acid sp. gr. 1.84 use 9 cc. of the acid sp. gr. 1.110. Ill ACID SULPHURIC, 10% A colorless liquid of specific gravity about 1.070, and containing about 10 per cent of H 2 S0 4 . TESTS OF PURITY The tests to be made are those given under Acid Sulphuric, sp. gr. 1.84. But for 1 cc. of the acid sp. gr. 1.84, use 15 cc. of the acid sp. gr. 1.070. (ACID) SULPHURIC ANHYDRIDE (SULPHUR TRIOXIDE) SO 3 . Mol. Wt. 80.06. Long, transparent, colorless prisms, which melt at 15 C. to a clear oily liquid, boiling at 46 C. On long keeping at a temperature below 25 C., the sulphuric anhydride po- lymerizes to a modification which forms long, silky, felted needles, which melt above 50 C., and which at a higher temperature become converted into the trioxide in vapor form, solidifying at 15 C., and boiling at 46 C. NOTE. Regarding the quantitative determination of sulphuric anhy- dride, see the statements given under Acid Sulphuric, Fuming. Also R. Rosenlecher, " Zur Gehaltsbestimmung der rauchenden Schwefelsaure und des Schwefelsaure anhydrids," Ztschr. anal. Chem., 37, 209 (1898); J. Chem. Soc., 74. II, 404 (1898). 38 CHEMICAL REAGENTS ACID SULPHURIC, FUMING zH 2 SO 4 ACID SULPHURIC, FUMING. FREE FROM NITROGEN A colorless, oily liquid, fuming in the air, and containing 8 to 10 per cent of free S0 3 (i.e., 83.1 to 83.5 per cent total 30,). TESTS OF PURITY Non-volatile Matter. 3 cc. of fuming sulphuric acid, on being evaporated and ignited, should leave no weighable residue. Nitric Acid. Dilute 1 cc. of fuming sulphuric with 9 cc. of water, and overlay the fluid on 5 cc. of diphenylamine solution (see Diphenylamine, page 100). No blue zone should form at the contact-surfaces of the two liquids. Ammonium Salts. Carefully add 2 cc. of fuming sulphuric acid, by drops, to 30 cc. of water, and add aqueous solution (1:6) of potassium hydroxide to alkalinity; on now adding 10 to 15 drops of Nessler's reagent, at most a pale-yellow, but in no case a brownish-red, color or precipitate may develop. Halogens. Add 1 cc. of fuming sulphuric acid, by drops, to 30 cc. of water; on now adding a few drops of silver nitrate solution, the liquid must not acquire more than a faint opalescent turbidity. Lead. On cautiously adding 10 cc. of fuming sulphuric acid, by drops, to 50 cc. of 85 per cent alcohol, a clear liquid should result, which should contain no precipitate of lead sulphate after standing two hours. Arsenic. A Marsh apparatus is set in operation, using 20 gm. of arsenic-free, granulated zinc, and arsenic-free, CHEMICAL REAGENTS 39 dilute (1:5) sulphuric acid. As soon as the air has been expelled from the apparatus, heat the reduction tube to redness, then run into the apparatus a cooled mixture of 10 cc. of the fuming sulphuric acid with 90 cc. of water. No deposit of arsenic should be visible in the reduction tube within half an hour. Quantitative Determination.* Weigh off accurately 1 gm. of fuming sulphuric acid in a Lunge-Rey stoppered bulb pipette, f and cautiously allow the acid to 1 run into 10 cc. of water, contained in a porcelain dish. The contents of the dish are now rinsed into a measuring flask of 100 cc. capacity, and the flask then filled up with water to the mark. After vigorously shaking, 25 cc. of the liquid are titrated with fifth normal potassium hydroxide solution, using methyl orange as indicator .J 1 cc. of fifth normal KOH = 0.008006 gm. of S0 3 , log. 90342. II ACID SULPHURIC, FUMING If An oily liquid, sometimes slightly colored, and often not perfectly clear. The acid fumes in the air, contains from * In accurate determinations, the acidity due to sulphurous acid must be deducted from that determined by titration. Regarding this, see Lunge, Chem.-tech., Untersuch.-Meth., 5 ed., 1, 395 (1904); J. Chem. Soc., 68, II, 413 (1895). fSee Lunge, Chem.-tech. Untersuch.-Meth., 5 ed., 1, 394 (1904); illustrated in Trade Catalogues of glassware, etc. t In order to ascertain the free SO 3 from the total SO 3 found by analysis, see the table in Lunge, Chem.-tech. Untersuch.-Meth., 5 ed., 1, 399 (1904); compare Thorpe's Diet, of Appld. Chem., 2 ed., 3, 711 (1895). ^[ This acid, which contains traces of nitric acid, is considerably cheaper than the foregoing acid, which is perfectly free from nitrogen. It is well adapted for use in laboratories where fuming sulphuric acid is very fre- quently used for the Kjeldahl nitrogen determinations. For accurate nitrogen determinations, however, it will be necessary to determine the nitrogen content of the acid by a blank test carried out in the manner above described. 40 CHEMICAL REAGENTS 8 to 10 per cent of free S0 3 , and is intended for nitrogen determinations by the Kjeldahl method. TESTS OF PURITY Nitrogen. Dilute 30 cc. of the fuming sulphuric acid in a retort with 200 cc. of water, and when cold add nitrogen- free solution of sodium hydroxide (sp. gr. 1.3), until strongly alkaline. Then add 3 gm. of zinc dust, distil off about 50 cc., and collect the distillate in a U-tube receiver con- taining about 10 cc. of water and 2 to 3 cc. of fifth normal hydrochloric acid. The distillate is then titrated with fifth normal potassium hydroxide solution, using methyl orange as indicator. The ammonia should not have consumed more than 0.2 cc. of the fifth normal hydrochloric acid. Quantitative Determination. The determination is car- ried out as described under Acid Sulphuric, Fuming, free from nitrogen. ACID SULPHURIC, WITH PHOSPHORIC ANHYDRIDE APPROXIMATELY 10, 15, OR 20% P 2 5 Sulphuric acid containing -phosphorus pentoxide. Approx- imately 10, 15, or 20 per cent of P 2 5 are the usual strengths. The preparation is employed in Kjeldahl's nitrogen determi- nation. TESTS OF PURITY Nitric Acid. Dilute 1 cc. of the solution of phosphoric anhydride in sulphuric acid with 9 cc. of water, and overlay this fluid on 5 cc. of diphenylamine solution (see Dipheny- lamine, page 100). No blue zone should form at the contact- surfaces of the two liquids. Ammonium Salts. Dilute 2 cc. of the solution of phos- phoric anhydride in sulphuric acid with 30 cc. of water, and add aqueous solution of potassium hydroxide (1:6) to alka- CHEMICAL REAGENTS 41 Unity, followed by 10 to 15 drops of Nessler's reagent. At most only a faint yellow, but in no case a brownish-red, color or precipitate should form. ACID SULPHURIC, FUMING, WITH PHOSPHORIC AN- HYDRIDE APPROXIMATELY 5, 10, 15, 20, OR 25% P 2 5 Fuming sulphuric acid containing phosphorus pentoxide; the usual grades contain approximately 5, 10, 15, 20, or 25 per cent of P 2 5 . The preparation is used in Kjeldahl's nitrogen determination. TEST OF PURITY Nitrogen. The nitrogen determination is carried out as described under Acid Sulphuric, Fuming. See footnote there. ACID SULPHUROUS SO 2 + Aq. Mol. Wt. 64.06. A clear, colorless liquid of specific gravity 1.029 to 1.035. The acid first reddens blue litmus paper, and then bleaches it. The liquid contains about 6 per cent of S0 2 . TESTS OF PURITY Non-volatile Matter. 10 cc. of sulphurous acid, on being evaporated and ignited, should leave no weighable residue. Quantitative Determination. Weigh off 10 gm. of sul- phurous acid in a measuring flask of 100 cc. capacity, and fill with boiled water up to the mark. Allow the fluid to run from a burette into 30 cc. of decinormal iodine solution, constantly shaken, until decoloration ensues. To effect this not more than 16.2 cc. of the acid solution should be required. 1 cc. of decinormal I = 0.003203 gm. of S0 2 , log. 50556. 42 CHEMICAL REAGENTS CUBES FOR GENERATING SULPHUROUS ACID Cube-like pieces, containing at least 20 per cent of sul- phurous acid. TEST OF STRENGTH Quantitative Determination. Introduce 1 gm. of the finely powdered cubes and 5 gm. of anhydrous sodium carbonate into a graduated flask of 100 cc. capacity; add 50 cc. of water, boil the mixture for about ten minutes, allow to cool, fill the flask up to the mark, and filter. Run the filtrate from a burette into a constantly shaken mixture of 30 cc. of decinormal iodine solution and 10 cc. of hydrochloric acid, until complete decoloration ensues. 1 cc. of decinormal I = 0.003203 gm. of S0 2 , log. 50556. ACID TANNIC (TANNIN) C 14 H 10 O 9 . Mol. Wt. 322.08. A yellowish powder, or crystal-like, lustrous scales. Tannic acid is soluble in 5 parts of water and in 2 parts of 85 per cent alcohol, yielding a clear liquid acid to litmus paper. Tannic acid is also soluble in about 8 parts of glycerin but is almost insoluble in ether. TESTS OF PURITY Inorganic Matter. 1 gm. of tannin on ignition should not leave a residue exceeding 0.002 gm. in weight. Sugar, Dextrin. On mixing 10 cc. of an aqueous (1 : 5) solution of tannic acid with 10 cc. of 85 per cent alcohol, the mixture must remain clear for one hour; nor should a turbidity occur on the further addition of 5 cc. of ether. CHEMICAL REAGENTS 43 Water. On drying tannic acid at 100 C., it should not lose more than 12 per cent of its weight. NOTE. Regarding the quantitative determination of tannic acid, see Fresenius, Anleitung zur quantitativen Analyse, Vol. II, 619 [or Lunge, Chem.-tech. Untersuch.-Meth., 4 ed., 3, 560 ff. (1900)]; Fresenius-Cohn Quantitative Analysis, Vol. II, 767 ff. (1904). ACID TARTARIC C 4 H 6 O 6 . Mol. Wt. 150.04. Colorless, prismatic crystals, or crystalline crusts, soluble in 0.8 part of water, and in 2.5 parts of 85 per cent alcohol. TESTS OF PURITY Sulphuric and Oxalic Acids, and Calcium. Separate 20. cc. portions of the aqueous (1 : 10) solution of the acid should show no change with barium chloride nor ammonium oxalate solutions; nor, when lowered to slight acidity by adding ammonia water, should a precipitate be obtained on adding calcium sulphate solution. Lead and other Metals. - (a) The solution of 5 gm. of tartaric acid in 20 cc. of water, with 12 cc. of ammonia water added, should not develop a brown color on the addition of hy- drogen sulphide water. (6) 20 cc. of the 1 : 10 aqueous solution should not be affected by hydrogen sulphide water. Inorganic Matter. 1 gm. of tartaric acid, on being ignited, should leave no weighable residue. Quantitative Determination. Dissolve 1 gm. of tartaric acid in 50 cc. of water, and titrate with normal sodium hydroxide solution, using phenolphthalein as indicator. 1 cc. of normal NaOH = 0.07502 gm. of C 4 H 6 6 , log. 87518. 44 CHEMICAL REAGENTS ACID THIOACETIC CHaCOSH. Mol. Wt. 76.09. A yellow liquid of penetrating odor, boiling between 92 and 97 C., and having a specific gravity of 1.070. Thioacetic acid is soluble in 16 parts of water, and easily in alcohol. The 6 per cent aqueous solution is used instead of hydrogen sulphide in chemical analysis.* TESTS OF PURITY Non-volatile Matter. 10 cc. of thioacetic acid, on being evaporated and ignited, should leave no weighable residue. Sulphuric Acid. On dissolving 5 cc. of thioacetic acid in 100 cc. of water, and adding barium chloride solution, no turbidity should occur, nor should a precipitate form. ALCOHOL ETHYLIC C 2 H 6 OH. Mol. Wt. 46.04. I ALCOHOL ABSOLUTE A clear, colorless liquid of specific gravity 0.796 to 0.798 (99 to 99.6 per cent by weight), and boiling at 78.5 C. Alcohol should not affect litmus paper. TESTS OF PURITY Residue. 50 cc. of alcohol, on being slowly evaporated, should leave no residue. * Regarding the use of thioacetic acid, see the following: R. Schiff and N. P. Tarugi, Ber., 27, 3437 (1894) [or Ztschr. anal. Chem., 34, 456 (1895)]; J. Chem. Soc., 68, II, 84 (1895). R, Schiff, Ber., 28, 1204 (1895); J. Chem. Soc., 68, II, 370 (1895). CHEMICAL REAGENTS 45 Fusel Oil.* On mixing 10 cc. of alcohol and 30 cc. of water in an Erlenmeyer flask, no turbidity or coloration should be observed, nor should any foreign odor be noticeable. A mixture of 10 cc. of alcohol and 0.20 cc. of 15 per cent sodium hydroxide solution, when evaporated down to 1 cc. and supersaturated with dilute sulphuric acid, should not have the odor of fusel oil. On rubbing a few drops of alcohol between the hands, no unpleasant odor should be noticeable. Molasses-Alcohol. On overlaying 5 cc. of alcohol on 5 cc. of concentrated sulphuric acid, no rose-red zone should form within one hour at the contact-surfaces of the two liquids. Aldehyde. On warming 10 cc. of alcohol with 5 drops of silver nitrate solution and 1 cc. of water for ten minutes on the water-bath (70 to 80 C.), neither a turbidity nor a precipitate should form. Organic Impurities.! The red color of a mixture of 10 cc. of alcohol and 1 drop of a 1 : 1000 potassium permanganate solution should not pass into yellow within twenty minutes. Metals and Tannin. On adding to 10 cc. of alcohol 1 cc. of ammonia water or 5 cc. of hydrogen sulphide water, no coloration should develop. * Regarding the quantitative determination of fusel oil, see Lunge, Chem.-tech. Untersuch.-Meth., 4 ed., 3, 422, 442 (1900); Allen, Com. Organ. Anal., 3 ed., Vol. I, p. 167 ff. (1898). A. Stutzer and O. Reitmaier, Ztschr. angew. Chem., 3, 522 (1890); J. Chem. Soc., 60, 622 (1891). G. Lunge, V. Meyer, and E. Schulze, Chem. Centralb. (3), 15, 854 (1884); J. Chem. Soc., 48, 708 (1885). M. Glasenapp, Ztschr. angew. Chem., 8, 657 (1895); J. Chem. Soc., 70, II, 277 (1896). H. Borntrager, Chem. Ztg., 13, Rep. p. 27 (1889); compare J. Chem. Soc., 56, 552 (1889), and 58, 669 (1890). See also Ztschr. Spiritusind., 1886, 362. t A partial decolorization of potassium permanganate occurs even with the purest alcohol. Compare also M. E. Barbet, J. Pharm. Chim., 19, 413, 457 (1889) [or Pharm. Ztg., 34, 481 (1889)]. P. Cazeneuve, Chem. Ztg., 13, Rep. p. 198 (1889); for similar article see J. Chem. Soc., 56, 928 (1889). Lang, Chem. Ztg., 17, 1544 (1893). 46 CHEMICAL REAGENTS II ALCOHOL, 95% A clear, colorless liquid of about 0.816 specific gravity (15.6 C.), and containing about 95 per cent by volume of absolute alcohol, C 2 H 5 OH. It boils at 78 C., is miscible in all proportions with water, and does not change the color of moistened litmus paper. TESTS OF PURITY Residue. 50 cc. of alcohol, on being slowly evaporated, should leave no weighable residue. Fusel Oil. Mix 10 cc. of alcohol, 5 cc. of water, and 1 cc. of glycerin, saturate a piece of clean, odorless blotting-paper with the mixture, and allow to evaporate spontaneously. No foreign odor should be noticeable after the evaporation. Aldehyde, Tannin. 10 cc. of alcohol mixed with 5 cc. of potassium hydroxide solution (5%) should not become yellow at once. Foreign Organic Matter, Aldehyde, etc. Shake 20 cc. of alcohol with 1 cc. of decinormal silver nitrate solution. Not more than a faint opalescence should appear, nor more than a faint brownish tint after exposing for six hours to diffused daylight. Furfural. Add ten drops of aniline and two or three drops of hydrochloric acid to 10 cc. of alcohol. No pinkish- red color should appear. Ill ALCOHOL, 85% This alcohol has a specific gravity of 0.830 to 0.834, and contains 87.2 to 85.6 per cent of alcohol, C 2 H 5 OH, by weight. In other respects it conforms to the requirements given under Alcohol Absolute. CHEMICAL REAGENTS 47 ALCOHOL AMYLIC C 5 Hn OH. Mol. Wt. 88.07: I AMYL ALCOHOL A clear, colorless liquid, neutral to litmus paper. Amyl alcohol is but slightly soluble in water, but is clearly miscible with alcohol, ether, and benzin. It has a specific gravity of 0.814 and boils at 131 C. TESTS OF PURITY Non-volatile Matter. 10 gm. of amyl alcohol evaporated on the water-bath should leave no weighable residue. Foreign Organic Matter (Furfural, etc.). (a) On shaking 5 cc. of amyl alcohol with 5 cc. of con- centrated sulphuric acid, the mixture should not acquire more than a faint yellow or reddish color. (6) On shaking 5 cc. of amyl alcohol with 5 cc. of potas- sium hydroxide solution, the amyl alcohol should not acquire any color. II AMYL ALCOHOL FOR GERBER'S FAT DETERMI- NATION A colorless liquid boiling at 128 to 130 C., and of specific gravity 0.815. TEST OF PURITY 1 cc. of amyl alcohol shaken with 10 cc. of concentrated sulphuric acid, and 11 cc. of water in a Gerber butyrometer, then centrifuged for two or three minutes, and then allowed to stand for twenty-four hours, must not exhibit an oily portion.* * Compare N. Gerber and M. M. Craandijk, Milch Ztg., 27, 611 (1898). Chem. Centralb., [5], 2, II, 907 (1898). 48 CHEMICAL REAGENTS ALCOHOL METHYLIC CH 3 OH. Mol. Wt. 32.03. A colorless, mobile liquid, readily miscible in all propor- tions with water, alcohol, ether, and fatty and volatile oils. Methyl alcohol has the specific gravity 0.796, and boils between 65 and 66 C. It should not redden blue litmus paper. TESTS OF PURITY Non- volatile Matter. 30 cc. of methyl alcohol evaporated on the water-bath should leave no weighable residue. Acetone and Ethyl Alcohol. Shake together thoroughly 50 cc. of double normal sodium hydroxide solution and 5 cc. of methyl alcohol in a mixing, cylinder, and add, with repeated shaking, 25 cc. of double normal iodine solution. No tur- bidity or flocculent precipitate should occur; nor should an odor of iodoform be perceptible. Empyreumatic Substances. 1 cc. of methyl alcohol should dissolve without turbidity in 10 cc. of water. On allowing 5 cc. of concentrated sulphuric acid to drop into 5 cc. of methyl alcohol while kept cold, the mixture should not acquire more than a slightly yellowish color. Aldehydes. On shaking 10 cc. of methyl alcohol with 10 cc. of sodium hydroxide solution (sp. gr. 1.3), the mixture should remain colorless. Substances Oxidizable by Permanganate. On adding 1 drop of decinormal potassium permanganate solution to 10 cc. of methyl alcohol, the red color of the liquid must not disap- pear within ten minutes. NOTE. Regarding the quantitative determination of methyl alcohol, as well as the quantitative determination of acetone in methyl alcohol, see Lunge, Chem.-tech. Untersuch.-Meth., 4 ed., 3, 693 (1900); compare G. Kramer, H. Strache, and J. Messinger as given in note under Acetone, p. 1. CHEMICAL REAGENTS 49 ALPHANAPHTHOL C 10 H 7 -OH. Mol. Wt. 144.06. Colorless, lustrous needles, having a phenolic odor, and melting at 95 C. Alphanaphthol is difficultly soluble in cold water, more readily soluble in warm water, and dissolves easily in alcohol, ether, benzene,, and chloroform. TESTS OF PURITY Inorganic Matter. 1 gm. of alphanaphthol ignited on platinum foil should leave no weighable residue. Organic Acids. On shaking 1 gm. of alphanaphthol with 100 cc. of water and filtering, the filtrate should not redden blue litmus paper. ALUMINUM OXIDE A1 2 O 3 . Mol. Wt. 102.2. A white, very bulky, hygroscopic powder,* used for Wis- licenus' f determination of tannin. Under a microscope, mag- nifying about 30 to 60 diameters, the powder appears in the form of partly transparent, flocculent masses, resembling vegetable tissue. TESTS OF PURITY Metallic Mercury and Aluminum. On moistening the preparation with water or alcohol, it acquires a gray color if any aluminum or mercury is present; if pure, it remains perfectly white. No globules of mercury or particles of metallic aluminum should be visible under the microscope. Absorptive Power for Tannin. 1 gm. of freshly ignited * The preparation must always be ignited before using in a determi- nation of tannin. t H. Wislicenus, Determination of Tannin Without Hide Powder, Ztschr. angew. Chem., 17, 801 (1904); J. Soc. Chem. Ind., 23, 765 (1904). Ztschr. anal. Chem., 44, 96 (1905); J. Chem. Soc., 88, II, 363 (1905). 50 CHEMICAL REAGENTS aluminum oxide is vigorously shaken for five minutes with 200 cc. of a solution of 4.5 gm. of pure tannin in sufficient water to make 1000 cc. (Use a flask with a rubber stopper.) The mixture is then heated for five minutes on the water- bath, and filtered. 50 cc. of the filtrate are evaporated in a weighed platinum or nickel dish, and the residue dried at 105 C. and weighed. The total residue obtained fro'm 50 cc. of the original tannin solution, and dried at 105 C., is afso ascertained. On now calculating the residue for 200 cc. of tannin solution, and deducting this from the total residue left from the tannin solution treated with the aluminum oxide, the result should show that 1 gm. of aluminum oxide absorbs 0.40 to 0.50 gm. of tannin. AMMONIA WATER NH 3 + H 2 O. Mol. Wt. NH 3 = 17.06. The aqueous solution of ammonia gas is a clear, colorless liquid, the specific gravity of which decreases as the ammonia content increases. For analytical purposes, two solutions of different concen- tration are ordinarily used, of which one has a specific gravity of about 0.96, and contains about 10 per cent of NH 3 , while the other, the concentrated, has the specific gravity of about 0.925, and contains about 20 per cent of NH 3 . In American laboratories a still more concentrated solution of ammonia is employed. Its strength is about 28 per cent and it is generally designated as " Stronger Ammonia Water." I AMMONIA WATER, 28% (STRONGER AMMONIA WATER) A clear, colorless liquid having a specific gravity of about 0.90, and containing about 28 per cent of NH 3 . CHEMICAL REAGENTS 51 TESTS OF PURITY Non- volatile Matter. On evaporating 3.5 cc. of the am- monia water on the water-bath, no weighable residue should remain. A trace of residue, however, is almost always left. Chlorides ; Pyridine. Dilute 3.5 cc. of the ammonia water with 30 cc. of water, and supersaturate with 20 cc. of nitric acid. The solution should remain colorless. This liquid should show no change on the addition of silver nitrate solu- tion. Heavy Metals. On diluting 2 cc. of the ammonia water with 20 cc. of water, and then adding a few drops of ammo- nium sulphide solution, no change should appear. Sulphates. Slightly acidify 3.5 cc. of the ammonia water with hydrochloric acid, and add barium chloride solution. No precipitate of barium sulphate should form on standing twelve hours. Carbon Dioxide. 3.5 cc. of the ammonia water with 15 cc. of calcium hydroxide solution should not at once become more than slightly opalescent. Quantitative Determination. Dilute 2 gm. of the am- monia water with about 50 cc. of water, and titrate with normal hydrochloric acid, using methyl orange indicator. 1 cc. of normal HC1 = 0.01706 gm. of NH 3 , log. 23198. II AMMONIA WATER, 20% (CONCENTRATED AMMONIA WATER) This solution of ammonia has the specific gravity 0.925 and contains about 20 per cent of NH 3 . TESTS OF PURITY The tests for non- volatile matter, chlorides, pyridine, heavy metals, sulphates, and per cent of NH 3 as described under 52 CHEMICAL REAGENTS Ammonia Water 28 per cent, are to be made. But, instead of 3.5 cc. of the 28 per cent use 5 cc. of the 20 per cent am- monia. The preparation should also conform to the following tests. Sulphides. On adding a few drops of an ammoniacal lead acetate solution to 5 cc. of the ammonia water, the liquid must not acquire a yellow or a brown color, nor should a dark precipitate form. Tar-Bases (Aniline, Pyridine, Pyrrol, etc.). Evaporate a mixture of 5 cc. of the ammonia water and 20 cc. of nitric acid on the water-bath. The residue on evaporation should have a pure white color. Calcium. A mixture of 5 cc. of the ammonia water with 20 cc. of water should exhibit no turbidity on the addition of ammonium oxalate solution. Magnesium. On adding ammonium phosphate solution to 10 cc. of the ammonia water, no precipitate should form on standing two hours. Carbonates. 10 cc. of the ammonia water, when mixed with 20 cc. of lime water and boiled, should not develop more than a very slight turbidity. Phosphates. To 10 cc. of the ammonia water add 40 cc, of nitric acid and 25 cc. of ammonium molybdate solution. No yellow precipitate should form in the liquid on standing two hours at about 40 C. Ill AMMONIA WATER, 10% This is the article termed " ammonia water'' throughout the text of this book. It contains about 10 per cent of NH 3r and has a specific gravity about 0.96. CHEMICAL REAGENTS 53 TESTS OF PURITY The tests of purity and details of execution are the same as those given under Ammonia Water, 20 per cent. But, in testing this use double the quantities of ammonia water employed in testing the 20 per cent. AMMONIUM ACETATE NH 4 C 2 H 3 O 2 . Mol. Wt. 77.1. A white, hygroscopic, crystalline mass, easily soluble in water and in alcohol. TESTS OF PURITY Non-volatile Matter. 3 gm. of ammonium acetate, when ignited, should leave no weighable residue. Chlorides. The solution of 1 gm. of ammonium acetate in 20 cc. of water, acidulated with 5 cc. of nitric acid, should show no change on the addition of silver nitrate solution. Sulphates. On adding 1 cc. of hydrochloric acid to a solution of 1 gm. of ammonium acetate in 20 cc. of water, followed by barium chloride solution, no precipitate of barium sulphate should form on standing twelve hours. Heavy Metals and Earths. The solution of 5 gm. of ammonium acetate in 100 cc. of water should not be affected by hydrogen sulphide water. Furthermore, the addition of ammonia water and ammonium oxalate solution should cause neither a coloration nor a turbidity. AMMONIUM CARBONATE (NH 4 )HCO 3 (NH 4 )NH 2 CO 2 . The term "ammonium carbonate" is generally applied to a mixture of ammonium bicarbonate and carbamate, forming a crystalline, white, translucent mass which readily effloresces, becomes opaque, and gives off an odor of ammonia. 54 CHEMICAL REAGENTS TESTS OF PURITY Non- volatile Matter. 5 gm. of ammonium carbonate, when ignited, should leave no weighable residue. Sulphates. Dissolve 5 gm. of ammonium carbonate in 100 cc. of water and 10 cc. of hydrochloric acid, heat the solution to boiling, and add barium chloride solution. No precipitate of barium sulphate should form on standing twelve hours. Chlorides and Thiosulphates. The solution of 2 gm. of ammonium carbonate in 50 cc. of water should not be affected on adding 10 cc. of nitric acid, followed by silver nitrate solution. Heavy Metals. To a solution of 5 gm. of ammonium carbonate in 30 cc. of water is added 30 cc. of dilute acetic acid, then 20 cc. of ammonia water, then a few drops of ammonium sulphide solution. No precipitate should form. nor should the liquid acquire a green or a brown color. Sulphocyanates. The solution of 1 gm. of ammonium carbonate in 20 cc. of water and 2 cc. of hydrochloric acid should not be reddened on adding 1 drop of ferric chloride solution. Tar Bases. Acidify 1 gm. of ammonium carbonate with 5 cc. of nitric acid, and evaporate the solution to dry ness on the water-bath. The residue must have a pure white color. AMMONIUM CHLORIDE NH 4 C1. Mol. Wt. 53.52. A white, crystalline powder, easily soluble in water. TESTS OF PURITY Non- volatile Matter. 3 gm. of ammonium chloride, when gently ignited, should leave no weighable residue. Phosphates and Arsenates. Dissolve 5 gm. of ammonium CHEMICAL REAGENTS 55 chloride in 20 cc. of water, and add to the clear solution 3 cc. of magnesia mixture and 10 cc. of ammonia water. No precipitate should form on standing twelve hours. Heavy Metals and Earths. 20 cc. portions of the aqueous 1 : 20 solution of the salt should not be affected by hydrogen sulphide water, ammonia water, ammonium sulphide solu- tion, and ammonium oxalate solution. Sulphates. On adding to 10 cc. of the 1 : 10 solution a few drops of hydrochloric acid, followed by barium chloride solution, no precipitate of barium sulphate should form on standing twelve hours. Sulphocyanates. Dissolve 1 gm. of ammonium chloride in 10 cc. of water, and add to the solution a few drops of hydrochloric acid and 1 drop of ferric chloride solution. The liquid should not acquire a red color. Tar Bases. On evaporating to dryness 1 gm. of ammo- nium chloride with 5 cc. of nitric acid on the water-bath, the residue must have a pure white color. AMMONIUM CITRATE SOLUTION A clear, colorless liquid, containing 150 gm. of pure, crys- tallized citric acid and 23 gm. of ammonia-nitrogen (= 27.93 gm. of NH 3 ) per liter. The solution has an acid reaction to litmus paper and is used for determining citrate-soluble phos- phoric acid in Thomas slag, by the method of Wagner. TEST FOR PROPER CONTENT OF AMMONIA-NITROGEN Dilute 25 cc. of the ammonium citrate solution with water to 250 cc. To 25 cc. of this diluted solution add 3 gm. of calcined magnesia and about 200 cc. of water, and distil, using a receiver containing 40 cc. of semi-normal sulphuric acid. After the distillation titrate the excess of acid with 56 CHEMICAL REAGENTS semi-normal potassium hydroxide solution, using methyl orange as indicator. 1 cc. of semi-normal H 2 S0 4 - 0.00702 gm. of N (log. 8463) = 0.00853 gm. of NH 3 , log. 9309. AMMONIUM DITHIOCARBONATE SOLUTION CO(SNH 4 ) 2 . Mol. Wt. 128.26. A yellow liquid of ammoniacal odor, and containing about 10 to 12 per cent of ammonium dithiocarbonate, about 8 per cent of ammonium chloride, and small quantities of ammo- nium sulphocyanate and ammonium sulphide. It is used as a substitute for hydrogen sulphide and ammonium sulphide. TESTS OF PURITY Non-volatile Matter. 10 cc. of ammonium dithiocarbonate solution, on being evaporated and ignited, should leave no weighable residue. Ammonium Carbonate. On adding 3 cc. of calcium chlo- ride solution to 10 cc. of the ammonium dithiocarbonate so- lution, no precipitate should form, even on warming. NOTE. Regarding the employment of ammonium dithiocarbonate, see M. Vogtherr, Ber. d. pharm. Ges., 8, 232 (1898) [or Pharm. Centrhl., 39, 692 (1898)]; J. Chem. Soc., 78, II, 241 (1900). AMMONIUM FLUORIDE NH 4 F. Mol. Wt. 37.07. White crystals, easily soluble in water, affording a solution which usually exhibits an acid reaction because of the pres- ence of NH 4 F-HF. TESTS OF PURITY Non- volatile Matter. 10 gm. of ammonium fluoride on ignition should leave no weighable residue. Chlorides. On dissolving 5 gm. of ammonium fluoride in CHEMICAL REAGENTS 57 25 cc. of water, and adding a few drops of nitric acid, followed by silver nitrate solution, the liquid must exhibit no change. Sulphates and Silicofluorides. Dissolve 5 gm. of ammo- nium fluoride in a platinum dish in 25 cc. of water, and add 25 cc. of hydrochloric acid, followed by barium chloride solution. No turbidity should ensue. Heavy Metals. Dissolve 5 gm. of ammonium fluoride in 25 cc. of water, add to the solution a few drops of hydro- chloric acid, and 10 cc. of hydrogen sulphide water. No change should appear. Now add ammonia water to alka- linity, and a few drops of ammonium sulphide solution; at most a slight greenish coloration may develop, but a precipi- tate should not form. AMMONIUM MOLYBDATE (NH 4 ) 6 Mo 7 O24 + 4H 2 O. Mol. Wt. 1236.43. Large, colorless, or slightly greenish crystals, soluble in water, which, when heated, liberate ammonia and water, leaving molybdic anhydride. TESTS OF PURITY Phosphates. 10 gm. of ammonium molybdate with 25 cc. of water and 15 cc. of ammonia water (sp. gr. 0.910) should afford a clear solution. Add this solution to 150 cc. of nitric acid (sp. gr. 1.20*). No yellow precipitate should form on standing two hours at a temperature of about 40 C. Heavy Metals. Dissolve 2 grn. of ammonium molybdate in 5 cc. of water and 5 cc. of ammonia water, and to the solution add 10 cc. of hydrogen sulphide water. Neither a green coloration nor a precipitate should form. Sulphates. On dissolving 1 gm. of ammonium molybdate * The ammonium molybdate solution should be added to the nitric acid gradually and with constant rotation; never otherwise. 58 CHEMICAL REAGENTS in 10 cc. of water, and acidifying the solution with nitric acid, no change should be observed on the further addition of barium nitrate solution. Chlorides. 20 cc. of the 1 : 10 aqueous solution acidified with nitric acid should show no change on the addition of silver nitrate solution. Quantitative Determination. The content of molybdic anhydride may be approximately determined by gently igniting about 1 gm. of the salt until the ammoniacal odor has disappeared, and then weighing the residue of molybdic anhydride; it should amount to about 81 per cent. The accurate determination is carried out in the manner described under Acid Molybdic Anhydride, on page 19. AMMONIUM NITRATE NH 4 NO 3 . Mol. Wt. 80.11. Colorless crystals easily soluble in water. TESTS OF PURITY The tests to be made are those described under ammonium chloride; and, in addition, tests for chlorides and nitrites. Chlorides. On dissolving 1 gm. of ammonium nitrate in 10 cc. of water, and adding a few drops of nitric acid, followed by silver nitrate solution, the liquid should remain unchanged. Nitrites. To the solution of 1 gm. of ammonium nitrate in 20 cc. of water are added 1 cc. of 16 per cent sulphuric acid and 1 cc. of a freshly prepared (0.5:100*) colorless solution of metaphenylenediamine hydrochloride: no yellow or yellowish-brown color should develop. * Should the solution of metaphenylenediamine hydrochloride already have a color it is to be decolorized before use by warming with ignited animal charcoal. CHEMICAL REAGENTS 59 AMMONIUM OXALATE (NH 4 ) 2 C 2 O 4 + H 2 O. Mol. Wt. 142.16. Colorless crystals, clearly soluble in 25 parts of cold water. The aqueous solution should be neutral to litmus paper. TESTS OF PURITY Non-volatile Matter. 3 gm. of ammonium oxalate on ignition should leave no weighable residue. Sulphates. Dissolve 5 gm. of ammonium oxalate in 200 cc. of water, heat the solution to boiling, and then add 10 cc. of hydrochloric acid, followed by barium chloride solution. No precipitate of barium sulphate should form on standing twelve hours. Chlorides. On adding to a solution of 1 gm. of ammo- nium oxalate in 25 cc. of water, 10 cc. of nitric acid, and a few drops of silver nitrate solution, no turbidity should develop on shaking. Heavy Metals. To a solution of 1 gm. of ammonium oxalate in 25 cc. of water add hydrogen sulphide water; the solution should remain unchanged. Now add to the liquid 5 cc. of ammonia water; no green color should develop, nor should a precipitate form. Quantitative Determination. This is to be made as de- scribed under Potassium Oxalate Neutral on page 178. 1 cc. of decinormal KMn0 4 = 0.007108 gm. of (NH 4 ) 2 C 2 4 + H 2 0, log. 85175. AMMONIUM PHOSPHATE (NH 4 ) 2 HPO 4 . Mol. Wt. 132.15. Colorless crystals, or white, crystalline powder, soluble in 4 parts of cold, or 0.5 part of boiling, water. The aqueous solution is slightly alkaline to litmus paper. 60 CHEMICAL REAGENTS TESTS OF PURITY Alkalies. The solution of 2 gm. of ammonium phosphate in 100 cc. of water is treated with lead acetate solution in slight excess to precipitate the phosphoric acid, and is then filtered. The excess of lead in the filtrate is then precipitated with hydrogen sulphide, the liquid filtered, the filtrate evap- orated to dryness, and the residue ignited. The residue should not be soluble in water, nor should it have an alkaline reaction. Arsenic. On shaking 1 gm. of powdered ammonium phosphate with 3 cc. of stannous chloride solution, the mixture should not darken within one hour. Carbonates and Sulphates. On adding hydrochloric acid to a solution of 1 gm. of ammonium phosphate in 20 cc. of water, no effervescence should take place; and on adding barium chloride solution, no precipitate of barium sulphate should form on standing twelve hours. Chlorides. On dissolving 1 gm. of ammonium phosphate in 20 cc. of water, and adding 5 cc. of nitric acid, followed by silver nitrate solution, not more than a very slight opalescence should develop. Nitrates. Dissolve 2 gm. of ammonium phosphate in 10 cc. of water, and to the solution add 1 drop of indigo solution (1:1000), followed by 10 cc. of concentrated sul- phuric acid. The liquid should still retain its blue color on standing one hour. Heavy Metals. On dissolving 2 gm. of ammonium phos- phate in 20 cc. of water, acidifying the solution with hydro- chloric acid, and then adding hydrogen sulphide water, no change should be seen. On now rendering the liquid alkaline with ammonia water, and adding a few drops of ammonium sulphide solution, no green color should develop, nor should a precipitate form. CHEMICAL REAGENTS 61 AMMONIUM SULPHATE (NH 4 ) 2 SO 4 . Mol. Wt. 132.14. Colorless crystals, soluble in 2 parts of cold, and in 1 part of boiling, water; insoluble in alcohol. TESTS OF PURITY Non-volatile Matter. 3 gm. of ammonium sulphate on ignition should leave no weighable residue. Chlorides. The solution of 2 gm. of ammonium sulphate in 20 cc. of water 'should not become turbid on acidifying with nitric acid and then adding silver nitrate solution. Heavy Metals. The solution of 2 gm. of ammonium sulphate in 20 cc. of water should remain unaffected by hydrogen sulphide, and by ammonia water with ammonium sulphide solution. Sulphocyanates. Dissolve 1 gm. of ammonium sulphate in 10 cc. of water; on adding to the solution several drops of hydrochloric acid and 1 drop of ferric chloric solution, the liquid should not acquire a red color. Phosphates and Arsenates. Dissolve 5 gm. of ammonium sulphate in 20 cc. of water, and add to the clear solution 3 cc. of magnesia mixture and 10 cc. of ammonia water. No precipitate should form on standing twelve hours. Nitrates. Dissolve 2 gm. of ammonium sulphate in 10 cc. of water, and add to the solution 1 drop of indigo solution (1:1000), followed by 10 cc. of concentrated sulphuric acid. The liquid should still retain its blue color on standing one hour. AMMONIUM SULPHOCYANATE (AMMONIUM THIOCYANATE) NH 4 SCN. Mol. Wt. 76.17. Colorless crystals, easily soluble in water and in alcohol. 62 CHEMICAL REAGENTS TESTS OF PURITY Non- volatile Matter. 2 gm. of ammonium sulphocyanate, on being ignited, should leave no weighable residue. Substances insoluble in Alcohol. 1 gm. of ammonium sulphocyanate should completely dissolve in 10 cc. of absolute alcohol, and yield a perfectly clear solution. Sulphates. On adding a few drops of hydrochloric acid, followed by barium chloride solution, to a solution of 1 gm. of ammonium sulphocyanate in 20 cc. of water, no reaction should be observed within five minutes. Heavy Metals. On dissolving 1 gm. of ammonium sul- phocyanate in 20 cc. of water, and adding to the solution several drops of ammonium sulphide solution, no precipitate should form, nor should a brown color develop. Iron. The solution of 1 gm. of ammonium sulphocyanate in 20 cc. of water should remain perfectly colorless on adding 0.5 cc. of hydrochloric acid. AMMONIUM SULPHIDE SOLUTION (AMMONIUM SULPHYDRATE SOLUTION) A colorless or yellowish liquid, produced by passing hydrogen sulphide into ammonia water. It is strongly alkaline towards litmus paper. TESTS OF PURITY Arsenic, Antimony, and Tin. On adding hydrochloric acid to 50 cc. of ammonium sulphide solution to acidity, hydrogen sulphide gas is liberated in copious amounts, but no colored precipitate should form. Non-volatile Matter. On evaporating and igniting 10 cc. of ammonium sulphide solution in a porcelain dish, no weighable residue should remain. CHEMICAL REAGENTS 63 Ammonium Carbonate. On adding 3 cc. of calcium chloride solution to 10 cc. of ammonium sulphide solution, no precipitate should form, even on warming. AMMONIUM THIOACETATE SOLUTION (SCHIFF'S REAGENT) CH 3 COSNH 4 . Mol. Wt. 93.15. A clear, yellowish liquid, having a faint odor resembling that of ammonium sulphide, and slightly alkaline to litmus paper. The solution contains about 30 per cent of ammonium thioacetate. TESTS OF PURITY Non-volatile Matter. 10 cc. of ammonium thioacetate solution on evaporation and ignition should leave no weighable residue. Ammonium Carbonate. On adding 3 cc. of calcium chloride solution to 10 cc. of ammonium thioacetate solution, no precipitate should form, even on warming. Sulphates. A mixture of 10 cc. of ammonium thioacetate solution with 10 cc. of diluted acetic acid should not immediately be rendered turbid on the addition of barium chloride solution. NOTE. The reagent can be kept only a short time unchanged; it readily becomes turbid. It is, therefore, advantageous to prepare only sufficient for eight to ten days' use, which may be done by dissolving the thioacetic acid in a slight excess of ammonia water. Regarding the use of ammonium thioacetate solution in analysis, see R. Schiff and N. P. Tarugi, Ber., 27, 3437 (1894) [or Ztschr. anal. Chem., 34, 456 (1895)] ; J. Chem. Soc., 68, II, 84 (1895). R. Schiff, Ber., 28, 1204 (1895); J. Chem. Soc., 68, II, 370 (1895). ANILINE C 6 H 5 -NH 2 . Mol. Wt. 93.09. A colorless, oily, strongly refractive liquid, which rapidly becomes brown on exposure to light and air. 64 CHEMICAL REAGENTS Aniline is soluble in about 35 parts of water. It solidifies in a freezing mixture, and then melts at 8 C. Its specific gravity is 1.027; its boiling point, 183 C. TESTS OF PURITY Hydrocarbons and Nitrobenzene. 5 cc. of aniline dissolved in 10 cc. of hydrochloric acid should form a clear fluid which, on being diluted with 15 cc. of water, should not become cloudy on cooling. NOTE. Regarding the examination of aniline, see Lunge, Chem.-tech. Untersuch.-Meth., 4 ed., 3, 745 (1900); compare Watts' Diet, of Chem., 1, 271 (1894). G. Schultz, Chemie des Steinkohlenteers, 1, 289 (1886); compare Thorpe's Diet, of Appld. Chem., 2 ed., 1, 162 (1895). ANTIMONY OXIDE (ANTIMONOUS OXIDE; ANTIMONY TRIOXIDE) Sb 2 O 3 . Mol. Wt. 288.4. A white powder, insoluble in water, but soluble in hydro- chloric acid, tartaric acid, alkali bitartrates, and in solutions of potassium or sodium hydroxide. Antimony trioxide is neutral to litmus paper. TESTS OF PURITY Arsenic. On dissolving 1 gm. of antimony trioxide in 3 cc. of hydrochloric acid (sp. gr. 1.19), and adding 3 cc. of stannous chloride solution, the mixture should not darken within one hour. Heavy Metals. Dissolve 1 gm. of antimony trioxide with the aid of heat in 30 cc. of sodium hydroxide solution (sp. gr. 1.3). Dilute the solution with 20 cc. of water and add hydrogen sulphide water. Neither a white nor a brownish- black precipitate should develop. Chlorides. Dissolve 1 gm. of antimony trioxide with the CHEMICAL REAGENTS 65 aid of heat in 30 cc. of sodium hydroxide solution (sp. gr. 1.3). Add to the solution 70 cc. of nitric acid, filter, and to the filtrate add silver nitrate solution. The liquid may exhibit at most a slight turbidity, but no precipitate should form. ARSENIC TRIOXIDE (ARSENOUS ACID; (Acio) ARSENOUS ANHYDRIDE) As 2 O 3 . Mol. Wt. 198. White, vitreous, or porcelain-like pieces, or white powder, soluble in 15 parts of boiling water. TESTS OF PURITY Non-volatile Matter. 1 gm. of arsenic trioxide cautiously heated in a porcelain dish should completely volatilize and leave no weighable residue. (Use a hood!) Barium Sulphate, Talcum, Calcium Sulphate, etc. 0.5 gm. of arsenic trioxide should be perfectly soluble in a mixture of 5 cc. of ammonia water and 5 cc. of water, and should yield a clear solution. Arsenic Sulphide. Dissolve 5 gm. of arsenic trioxide in a mixture of 5 cc. of sodium hydroxide solution and 15 cc. of water; on adding to the clear solution 2 drops of lead acetate solution, no color reaction should occur. Quantitative Determination. Dissolve * 1 gm. of arsenic trioxide with the aid of 6 gm. of potassium bicarbonate in 50 cc. of boiling water, then allow to cool to 15 C., and add sufficient water to make the whole measure 100 cc. Dilute 10 cc. of this solution with 50 cc. of water, and titrate with decinormal iodine solution. * It may be quicker to dissolve 1 gm. in a freshly prepared solution of sodium hydroxide (sulphur-free), slightly acidulate with hydrochloric acid, and then add the 6 gm. of bicarbonate. No heat is necessary in this case. 66 CHEMICAL REAGENTS 1 cc. of decinormal I = 0.00495 gm. of As 2 3 , log. 69461. NOTE. Both the lump and the powder forms of arsenic trioxide must answer the above requirements. The tests here given should be carried out with the powdered preparation, as the whole pieces or lumps dissolve with difficulty. Regarding the use of arsenic trioxide in volumetric analysis, see Mohr's Lehrb. Chem.-anal. Titriermeth., 7 ed., p. 389 ff. (1896); Sutton, Volumet. Anal., 9 ed., p. 139 (1904). AZOLITMIN Azolitmin is a particularly pure, water-soluble coloring matter made from litmus. It occurs in the form of blackish- violet scales. Azolitmin is used as an indicator, usually in 1 per cent solution. To make this, dissolve 1 gm. of azolitmin in 80 cc. of water with the aid of heat, then add 20 cc. of 85 per cent alcohol, and filter the solution when cold. TEST OF SENSITIVENESS Add 0.1 cc. of the above azolitmin solution to 50 cc. of distilled water, as free as possible from alkali and carbon dioxide. The bluish-red color of the liquid should be changed to red by the addition of, at most, 0.05 cc. of decinormal hydrochloric acid, and must be changed to bluish-violet by the addition of, at most, 0.05 cc. of decinormal potassium hydroxide. NOTE. The distilled water used in this test must be freed from carbon dioxide by boiling in a platinum vessel, and must be cooled in completely filled flasks with the exclusion of air. BARIUM ACETATE Ba(C 2 H 3 O 2 ) 2 + H 2 O. Mol. Wt. 273.46. A white, crystalline powder, soluble in 2 parts of water and in about 100 parts of alcohol. CHEMICAL REAGENTS 67 TESTS OF PURITY Chlorides. The solution of 1 gm. of barium acetate in 20 cc. of water, acidulated with nitric acid, must exhibit no turbidity on the addition of silver nitrate solution. Calcium and Alkalies. Dissolve 5 gm. of barium acetate in 200 cc. of water, add to the solution 2 cc. of hydrochloric acid and heat to boiling. Now add 15 cc. of 16 per cent sulphuric acid, allow to stand twelve hours, filter, and mix the filtrate with 85 per cent alcohol. At most a faint opales- cence should be observed; and on evaporating in a platinum dish and igniting, not more than 0.004 gm. of residue should remain. Heavy Metals. 20 cc. of the 1 : 20 aqueous solution should not acquire a dark color or afford a precipitate on the addi- tion of hydrogen sulphide water; ammonia water with ammo- nium sulphide solution should produce the same negative results. Nitrates. The blue color imparted by 1 drop of 1 : 1000 indigo solution to a solution of 1 gm. of barium acetate in 10 cc. of water should not disappear on the addition of 10 cc. of concentrated sulphuric acid. BARIUM CARBONATE BaCO 3 . Mol. Wt. 197.4. A white powder, almost insoluble in water. TESTS OF PURITY Solubility in Dilute Hydrochloric Acid. 5 gm. of barium carbonate should be completely soluble in 10 cc. of hydro- chloric acid diluted with 50 cc. of water. Calcium and Alkalies. Dissolve 5 gm. of barium carbo- nate in 10 cc. of hydrochloric acid and 200 cc. of water, and heat the solution to boiling. Then add 15 cc. of 16 per cent 68 CHEMICAL REAGENTS sulphuric acid, allow to stand twelve hours, filter, and mix the filtrate with 85 per cent alcohol. Not more than a faint opalescence should be visible, and on evaporating in a plati- num dish and igniting, not more than 0.003 gm. of residue should remain. Heavy Metals. Neither hydrogen sulphide water, nor ammonia water with ammonium sulphide solution, should produce a dark color or a precipitate on being added to a solution of 1 gm. of barium carbonate in 5 cc. of hydrochloric acid and 15 cc. of water. Chlorides. The solution of 1 gm. of barium carbonate in 5 cc. of nitric acid and 15 cc. of water (solution is hastened by heating) should not be affected by silver nitrate solution. Nitrates. The blue color imparted by 1 drop of a 1 : 1000 indigo solution to the solution of 1 gm. of barium carbonate in 10 cc. of diluted acetic acid should not disappear on the addition of 10 cc. of concentrated sulphuric acid. NOTE. Regarding the volumetric determination of barium carbonate, see Mohr's Lehrb. Chem.-anal. Titriermeth., 7 ed., p. 133 (1896); Sutton, Volumet. Anal., 9 ed., p. 70 (1904). BARIUM CHLORIDE BaCl 2 + 2H 2 O. Mol. Wt. 244.33. Colorless crystals, soluble in 2.5 parts of cold, and in 1.5 parts of hot, water, and insoluble in absolute alcohol. The aqueous solution is neutral to litmus paper. TESTS OF PURITY Alkalies. Dissolve 3 gm. of barium chloride in 100 cc. of water, add 2 cc. of hydrochloric acid and heat to boiling; then add 10 cc. of 16 per cent sulphuric acid, allow to stand twelve hours, and filter. On evaporating the filtrate in a platinum dish and igniting, a residue weighing more than 0.001 gm. should not remain. CHEMICAL REAGENTS 69 Strontium and Calcium Chlorides. On shaking 1 gm. of powdered barium chloride with 20 cc. of absolute alcohol five minutes, and then filtering, the filtrate on being evapo- rated and ignited should leave no weighable residue. Heavy Metals. 20 cc. of the 1 : 20 aqueous solution should not afford a dark coloration nor a precipitate when hydrogen sulphide water is added; nor when ammonia water and ammonium sulphide solution are added. Nitrates. On adding 1 drop of a 1 : 1000 indigo solution to a- solution of 1 gm. of barium chloride in 10 cc. of water, the blue color must not disappear on the addition of 10 cc. of concentrated sulphuric acid. Chlorates. On warming 2 gm. of powdered barium chlo- ride with 10 cc. of concentrated hydrochloric acid in a test tube, neither the crystals nor the liquid should acquire a yellow color; nor should the odor of chlorine become per- ceptible. BARIUM DIOXIDE (BARIUM SUPER- OR PEROXIDE) BaO 2 . Mol. Wt. 169.4. White, or grayish-white powder, insoluble in water, but soluble in cold hydrochloric acid with the formation of hydrogen peroxide. The preparation should contain at least 82 per cent of Ba0 2 . TEST OF PURITY Quantitative Determination. Introduce 1 gm. of barium peroxide into a graduated flask of 100 cc. capacity, and add to it 5 gm. of potassium iodide; dissolve in 30 cc. of water and 10 cc. of hydrochloric acid, and allow the mixture to stand in the stoppered flask for about half an hour, with frequent shaking. Then fill the flask to the mark, mix, and titrate 10 cc. of the mixture with decinormal sodium thio- 70 . CHEMICAL REAGENTS sulphate solution, using starch solution as the indicator. At least 9.7 cc. of decinormal sodium thiosulphate should be required. 1 cc. of decinormal Na 2 S 2 3 = 0.00847 gm. of Ba0 2 , log. 92788. BARIUM HYDROXIDE (BARIUM HYDRATE) Ba(OH) 2 + 8H 2 O. Mol. Wt. 315.54. White crystals, soluble in 20 parts of cold, and in 3 parts of boiling, water, a trace of barium carbonate almost inva- riably remaining undissolved. The aqueous solution is alka- line to litmus paper. TESTS OF PURITY Chlorides. The solution of 1 gm. of barium hydroxide in 5 cc. of nitric acid and 15 cc. of water should not be affected by silver nitrate solution. Calcium and Alkalies. Dissolve 3 gm. of barium hydrox- ide in 100 cc. of water, add 5 cc. of hydrochloric acid, and heat to boiling. Then add 10 cc. of diluted sulphuric acid, allow to stand twelve hours, and filter. On evaporating the filtrate in a platinum dish and igniting, a residue weighing more than 0.002 gm. should not remain. Heavy Metals. 20 cc. of the 1 : 20 aqueous solution acidulated with hydrochloric acid should not acquire a dark color, nor yield a precipitate on the addition of hydrogen sulphide water; nor should it do so on adding ammonia water to alkaline reaction, followed by ammonium sulphide solution. Sulphides. The 1 : 20 aqueous solution of barium hy- droxide, when acidulated with hydrochloric acid, should not have an odor of hydrogen sulphide, nor should it acquire a dark color on adding lead acetate solution. Quantitative Determination. Dissolve 1 gm. of barium. CHEMICAL REAGENTS 71 hydroxide in 100 cc. of water, add 1 drop of methyl orange solution, and titrate with normal hydrochloric acid. Not less than 6.3 cc. of the normal acid should be necessary to produce the red end-point. 1 cc. of normal HC1 = 0.15777 gm. of Ba(OH) 2 + 8H 2 0, log. 19802. BARIUM HYDROXIDE SOLUTION (BARYTA WATER) A clear, colorless liquid, of strongly alkaline reaction. Baryta water contains 3.3 per cent of crystallized barium hydroxide, Ba(OH) 2 + 8H 2 0. TESTS OF PURITY The tests to be made are those given under Barium Hy- droxide. But for each gram of crystallized barium hydrox- ide, 30 cc. of baryta water are to be taken. The quantita- tive determination is made as follows. Quantitative Determination. Titrate 50 cc. of baryta water with normal hydrochloric acid, using methyl orange as the indicator. At least 10.5 cc. of normal hydrochloric acid should be required to produce the red end-point. 1 cc. of normal HC1 = 0.15777 gm. of Ba (OH) 2 + 8H 2 0, log. 19802. BARIUM NITRATE Ba(NO 3 ) 2 . Mol. Wt. 261.48. Colorless crystals, soluble in 20 parts of cold, and in 2.8 parts of boiling, water. The aqueous solution is neutral to litmus paper. Barium nitrate is insoluble in absolute alcohol. TESTS OF PURITY Chlorides. The 1 : 20 aqueous solution acidulated with nitric acid should show no change on the addition of silver nitrate solution. 72 CHEMICAL REAGENTS Alkalies and Heavy Metals. The test is to be carried out as described under Barium Chloride. BARIUM SULPHIDE Gray, hard, amorphous pieces, prepared by fusing a mixture of heavy-spar, powdered coke, and sodium chloride. On allowing hydrochloric acid to flow over barium sulphide, a uniform current of hydrogen sulphide should be generated. TEST OF PURITY Arsenic. Heat 100 cc. of nitric acid (sp. gr. 1.3) in a porcelain dish to 70 to 80 C., and add 10 gm. of finely pow- dered barium sulphide, gradually, in quantities of 0.2 to 0.3 gm. at a time; when all has been added, heat to boiling. Then add to the mixture 100 cc. of arsenic-free, dilute sul- phuric acid (1:5), evaporate on the water-bath as far as possible; continue to heat on the sand-bath until vapors of sulphuric acid begin to be evolved; cool, and finally stir the cooled residue with 100 cc. of water. Set a Marsh apparatus in operation, using 20 gm. of arsenic- free, granulated zinc and dilute (1:5) sulphuric acid, and then introduce the above residue suspended in water, in small quantities at a time, into the generating flask of the Marsh apparatus. No deposit of arsenic should be observable in the reduction tube after the apparatus has been in opera- tion two hours. NOTE. This chemical serves for the preparation of arsenic-free hydrogen sulphide. The hydrochloric acid to be used for this purpose is to be tested for arsenic. BENZENE (BENZOL) C 6 H 6 . Mol. Wt. 78.04. A clear, colorless liquid, of characteristic odor, insoluble in water, but easily soluble in alcohol and in ether. Benzene CHEMICAL REAGENTS 73 solidifies at C. to rhombic, crystalline scales, which melt a t 4. 4 C. Its specific gravity is 0.883, and it boils at 80.5 C. TESTS OF PURITY Thiophene.* On shaking 50 cc. of benzene with 20 cc. of concentrated sulphuric acid, the sulphuric acid should remain colorless; on now adding a crystal of isatin, and again shaking and allowing to stand one hour, the sulphuric acid should have neither a green nor a blue color. Carbon Disulphide.j Thoroughly mix 50 cc. of benzene with 50 gm. of alcoholic potassium hydroxide solution (11 gm. of potassium hydroxide in 90 gm. of absolute alcohol), and allow the mixture to stand several hours at a temperature of about 20 C. Shake with about 100 cc. of water, remove the aqueous solution from the benzene, neutralize the latter with acetic acid, and add copper-sulphate solution. No precipitate should form. BENZIDINE (PARADIAMINODIPHENYL) (C 6 H 4 ) 2 (NH 2 ) 2 . Mol. Wt. 184.17. A grayish-yellow, crystalline powder, melting at 122 C. Benzidine is very difficultly soluble in cold water, but more readily in boiling water, in alcohol, and in ether. TEST OF PURITY Sulphur and Sulphates. Thoroughly mix 5 gm. of ben- zidine with a mixture of 5 gm. of anhydrous sodium carbonate *See C. Schwalbe: "On the Sulphur Content of Pure Benzenes"; Ztschr. Farb.-Textl. Ind., 3, 461 (1904); J. Chem. Soc. 88, I, 124 (1905). Ztschr. Farb.-Textl. Ind., 4, 113 (1905); J. Soc. Chem. Ind., 24, 271 (1905). t F. Frank: Chem. Ind., 24, 237, 262 (1901) [or Chem. Centralb., (5) 6, I, 1251 (1901)]; J. Soc. Chem. Ind., 20, 566 (1901). 74 CHEMICAL REAGENTS and 2 gm. of potassium nitrate, and cautiously incinerate in a platinum crucible. When cold, dissolve. the melt in 50 cc. of water, filter, add to the filtrate 20 cc. of hydrochloric acid, and heat to boiling. On now adding barium chloride solu- tion, no precipitate of barium sulphate should form on standing twelve hours. BENZIN (PETROLEUM ETHER; PETROLEUM BENZIN) A colorless, non-fluorescent, very inflammable liquid of strong but not unpleasant odor. Specific gravity 0.640 to 0.670. Benzin distils between 40 and 75 C., and does not solidify at C * TESTS OF PURITY Non- volatile Matter and Heavy Oils. 20 gm. of benzin warmed on the water-bath should volatilize and leave no residue. When dropped upon paper, and allowed to evapo- rate, it should leave no greasy spot. Sulphur Compounds or Reducing Agents. Mix 1 cc. of benzin with 5 cc. of a solution of silver nitrate in alcoholic ammonia; on plunging the test-tube containing the mixture into water of about 50 C., no brown coloration should develop. BISMUTH SUBNITRATE (BISMUTH BASIC NITRATE) A white, microcrystalline powder, insoluble in water and in alcohol, but soluble in diluted hydrochloric, nitric, or sulphuric acid. On shaking bismuth subnitrate with water, it imparts an acid reaction to the latter. * Benzin is a mixture of various hydrocarbons. It has, therefore, no sharp boiling point, but distils within rather wide limits. The test- ing of benzin for benzene by nitrating the latter with nitro-sulphuric acid was not adopted here, because it is impossible to obtain a benzin that will stand this test. CHEMICAL REAGENTS 75 TESTS OF PURITY Carbonates, Lead, Copper, Salts of the Alkalies, etc. 0.5 gm. of bismuth subnitrate should completely dissolve in 25 cc. of cold 16 per cent sulphuric acid without the evolu- tion of carbon dioxide, and should yield a clear solution. 10 cc. of this solution, with an excess of ammonia water, should yield a colorless filtrate. Another 10 cc. of this solution, diluted with 100 cc. of water and treated with hydrogen sulphide to completely precipitate the bismuth, should yield a filtrate leaving no weighable residue on evapo- ration and ignition. Chlorides. On adding silver nitrate solution to a solution of 0.5 gm. of bismuth subnitrate in 5 cc. of nitric acid, not more than a slight opalescent turbidity should develop. Sulphates. The solution of 0.5 gm. of bismuth sub- nitrate in 5 cc. of nitric acid should show no change on the addition of 5 to 10 drops of barium nitrate solution. Ammonia. On warming 1 gm. of bismuth subnitrate with 10 cc. of sodium hydroxide solution (sp. gr. 1.3), no ammonia should be evolved (to be ascertained by moistened litmus paper). Residue on Ignition. On igniting 1 gm. of bismuth sub- nitrate, there should remain a residue of bismuth oxide weighing 0.79 to 0.82 gm. Arsenic. The residue of bismuth oxide obtained above is triturated to a fine powder, and dissolved in sulphuric acid with heat. Set a Marsh apparatus in operation, using 20 gm. of arsenic-free, granulated zinc, and dilute (1 : 5) sulphuric acid, then introduce the bismuth solution in small quantities at a time into the evolution flask. No deposit of arsenic should be visible in the reduction tube within half an hour. 76 CHEMICAL REAGENTS BROMINE Br. Atomic Wt. 79.96. A dark red, almost black liquid, of specific gravity 2.97 to 2.99, and boiling at 63 C. Bromine dissolves in about 30 parts of water. It is easily soluble in alcohol, ether, chloroform, and carbon disulphide. TESTS OF PURITY Non- volatile Matter. 5 gm. of bromine warmed in a porce- lain dish on the water-bath should volatilize and leave no weighable residue. Sulphuric Acid, Chlorine, and Organic Bromine Compounds (Bromoform; Carbon Tetrabromide). 5 gm. of bromine dis- solve without turbidity of any kind in 100 cc. of water after adding, by drops, 20 cc. of ammonia water.* Evapo- rate to dryness the solution of ammonium bromide thus obtained, and test for: (a) Sulphuric Acid. Dissolve 2 gm. of the ammonium bromide in 60 cc. of water, and add 0.5 cc. of hydrochloric acid followed by barium chloride solution. A precipitate of barium sulphate should not form on standing twelve hours. (6) Chlorine. Dissolve 0.1 gm. of the ammonium bromide in 10 cc. of water, and mix with 4 cc. of ammonium carbonate solution (1 part of ammonium carbonate, 1 part of ammonia water, and 3 parts of water), then add 12 cc. of decinormal silver nitrate solution, filter, * Organic bromine compounds gradually separate out in the form of oily drops. CHEMICAL REAGENTS 77 and acidulate the filtrate with nitric acid. Only a slight opalescence should develop.* Iodine. Dissolve 1 gm. of bromine in 40 cc. of water, add 4 gm. of powdered iron, and shake two to three minutes. Filter, add starch solution to the filtrate, and cautiously allow a few drops of bromine water to flow upon the surface. A blue zone should not form at once below the yellowish upper portion of the liquid. BROMINE WATER A saturated, aqueous solution, containing about 3 per cent of Br. TESTS OF PURITY Sulphuric Acid. Add 0.5 cc. of hydrochloric acid and barium chloride solution to 50 cc. of bromine water, and boil the liquid until the bromine has been completely expelled from it. No precipitate of barium sulphate should separate on standing one hour. Bromine Content. Let 10 cc. of bromine water run into a solution of 5 gm. of potassium iodide in 100 cc. of water, allow to stand half an hour in a stoppered flask, and then titrate with decinormal sodium thiosulphate solution. 1 cc. of decinormal Na 2 S 2 3 = 0.007996 gm. of Br., log. 90287. BRUCINE C 23 H 26 N 2 O4 + 2H 2 Of. Mol. Wt. 430.32. Small, white crystals, difficultly soluble in cold, but more readily soluble in boiling, water. Brucine is easily soluble * Some opalescence always occurs because silver bromide is not abso- lutely insoluble in ammonium carbonate solution. Regarding the quantitative determination of chlorine in bromine, see Topf. Pharm. Ztg., 37, 364 (1892). f Brucine also crystallizes with 4 molecules of water; then it dissolves in 320 parts of cold, and in 150 parts of boiling, water. 78 CHEMICAL REAGENTS in 85 per cent alcohol, and in chloroform. The aqueous solution of brucine is alkaline to litmus paper, and is levo- gyrate. When dried at 100 C., brucine melts at 178 C. TESTS OF PURITY Water of Crystallization. 1 gm. of brucine dried at 100 C. to constant weight should lose not more than 0.083 gm. Nitric Acid. 0.01 gm. of brucine should dissolve in 5 cc. of pure concentrated sulphuric acid, and yield a colorless or, at most, scarcely perceptible faint pink color.* Strychnine. Treat 0.5 gm. of brucine with 5 gm. of absolute alcohol at the ordinary temperature for one hour, with frequent shaking. Filter, transfer a portion of the undissolved substance to a watch glass, allow it to dry there- on, and then dissolve it in a few drops of concentrated sul- phuric acid. To this solution add a small crystal of potassium dichromate. A play of colors, from blue through violet and red into green, is evidence of the presence of strychnine. Quantitative Determination. Dissolve 0.25 gm. of brucine in 50 cc. of 85 per cent alcohol, and titrate with decinormal hydrochloric acid, using lacmoid as the indicator. At least 5.8 cc. of decinormal acid should be required to produce the red end-point. 1 cc. of decinormal HC1 = 0.043032 gm. of C 23 H 26 N 2 4 + 2H 2 0, log. 63379. CADMIUM BOROTUNGSTATE SOLUTION A perfectly clear, yellowish, or light brown, liquid, having a specific gravity of 3.28. CADMIUM AND POTASSIUM IODIDE (POTASSIUM-CADMIUM IODIDE) A white powder, easily soluble in water and in alcohol. * The sulphuric acid should be tested with diphenylamine to insure the absence of nitric acid. CHEMICAL REAGENTS 79 Cadmium and potassium iodide readily acquires a slight yellowish color on keeping. TESTS OF PURITY Foreign Metals. (a) Dissolve 1 gm. of cadmium and potassium iodide in 20 cc. of water, add to the solution 2 cc. of potassium hydroxide solution, and filter. Neither before nor after acidulating with hydrochloric acid should the filtrate yield a precipitate with hydrogen sulphide water. (6) Dissolve 1 gm. of cadmium and potassium iodide in 30 cc. of water, and add to the solution 5 cc. of ammonia water. The liquid should remain clear and colorless on shaking. Sulphates. The 1 : 20 aqueous solution acidulated with hydrochloric acid should not be affected by barium chloride solution. lodic Acid. The 1 : 20 solution freshly prepared with boiled water should not immediately give a blue color on adding starch solution followed by 2 or 3 drops of dilute sulphuric acid. CALCIUM CARBONATE PRECIPITATED CaCO 3 . Mol. Wt. 100.1. A white, crystalline powder, almost insoluble in pure water (1:27000), but somewhat soluble in carbonated water. TESTS OF PURITY Solubility in Hydrochloric, Nitric, and Acetic Acids. 5 gm. of calcium carbonate should be completely dissolved by 25 cc. of hydrochloric acid, and by 25 cc. of nitric acid, and by 60 cc. of 30 per cent acetic acid. The solutions must be clear and colorless. 80 CHEMICAL REAGENTS Heavy Metals. Dissolve 1 gm. of calcium carbonate in 5 cc. of hydrochloric acid and 25 cc. of water. This solu- tion should not afford a precipitate or a green color with hydrogen sulphide water; nor with ammonia water in excess accompanied by 2 to 3 drops of ammonium sulphide solution. Magnesium. Dissolve 1 gm. of calcium carbonate in 5 cc. of hydrochloric acid and 5 cc. of water. To this solu- tion add 10 cc. of ammonia water and an excess of ammonium oxalate solution, allow to stand five hours, filter, and add to the filtrate sodium phosphate solution. No precipitate should form on standing twelve hours. Sulphates. Dissolve 1 gm. of calcium carbonate in 5 cc. of hydrochloric acid and 25 cc. of water, boil the solution five minutes, and add barium chloride solution. No precipi- tate of barium sulphate should form on standing twelve hours. Chlorides. 1 gm. of calcium carbonate dissolved in 5 cc. of nitric acid and 25 cc. of water, must show no change on the addition of silver nitrate solution. Phosphates. Dissolve 10 gm. of calcium carbonate in 50 cc. of nitric acid, add 25 cc. of ammonium molybdate solution, and allow to stand twelve hours at a temperature of 30 to 40 C. No yellow precipitate should form. Alkalies and Calcium Oxide. 1 gm. of calcium carbonate shaken with 50 parts of boiled and cooled water should yield a filtrate without an alkaline reaction, which on evapo- ration and ignition should leave a residue weighing at most 0.001 gm. CALCIUM CHLORIDE, CRYSTALS CaCl 2 + 6 H 2 O. Mol. Wt. 219.09. Colorless crystals, deliquescent in the air, and easily soluble in water and in alcohol. The 1 : 10 solution should be neutral to litmus paper. CHEMICAL REAGENTS 81 TESTS OF PURITY Substances Insoluble in Absolute Alcohol. 2 gm. of cal- cium chloride should completely dissolve in 20 cc. of ab- solute alcohol. Heavy Metals. 20 cc. of the 1 : 10 aqueous solution should show no change on adding 1 cc. of hydrochloric acid and hydrogen sulphide water. On .further adding 5 cc. of am- monia water and 2 to 3 drops of ammonium sulphide solu- tion, no green color should develop, nor should a precipitate form. Sulphates. On adding barium chloride solution to the solution of 2 gm. of calcium chloride in 20 cc. of water acid- ulated with 0.5 cc. of hydrochloric acid, no precipitate should form on standing twelve hours. Ammonium Salts. On boiling 2 gm. of calcium chloride with 10 cc. of sodium hydroxide solution, no ammonia should be evolved (to be ascertained by moistened litmus paper). Barium. On adding 20 cc. of calcium sulphate solution to the solution of 2 gm. of calcium chloride in 20 cc. of water, no precipitate should form within three hours. Arsenic. Introduce 10 gm. of arsenic-free, metallic zinc into the generating flask of a Marsh apparatus, and start the hydrogen with dilute (1 : 5) sulphuric acid. Dissolve 5 gm. of calcium chloride in 20 cc. of water, introduce the solution in 'small quantities at a time into the Marsh apparatus, and maintain the stream of gas for about one hour. No deposit of arsenic should be visible in the reduction tube within this time. CALCIUM CHLORIDE, DRY, GRANULATED White, granular, porous masses in pieces the size of peas, the form preferred for drying gases. This is the preparation to be used for filling absorption tubes for the determination 82 CHEMICAL REAGENTS of carbon dioxide, as in elementary analyses, but it should be previously rendered neutral by means of carbonic acid. CALCIUM CHLORIDE FUSED White crystalline masses; formula: practically CaCl 2 . Fused calcium chloride is chiefly used for drying liquids, e.g., ethers, esters, ethereal oils, hydrocarbons, etc. CALCIUM HYDROXIDE (SLAKED LIME) Ca(OH) 2 . Mol. Wt. 74.11. A white, dry powder. The article is tested as to purity by the methods detailed under Calcium Oxide from Marble, on page 83. CALCIUM OXIDE, FROM ICELAND SPAR CaO. Mol. Wt. 56.1. White pieces in the form of Iceland spar crystals. TESTS OF PURITY Solubility and Sulphates. 3 gm. of calcium oxide slaked with 10 cc. of water should completely dissolve in 15 cc. of hydrochloric acid without effervescence. Dilute the solution with 50 cc. of water, heat to boiling, and add barium chloride solution. On standing twelve hours, not more than a scarcely 'perceptible, unweighable trace of barium sulphate should be present. Phosphates. Slake 3 gm. of calcium oxide with 10 cc. of water, dissolve in 25 cc. of nitric acid, and add 25 cc. of ammonium molybdate solution. No yellow precipitate should form on standing twelve hours at 30 to 40 C. Chlorides. Slake 3 gm. of calcium oxide with 10 cc. of CHEMICAL REAGENTS 83 water, dissolve in 20 cc. of nitric acid, and dilute the solution with 10 cc. of water. The solution should show no change on the addition of silver nitrate solution. Iron. Slake 1 gm. of calcium oxide with 5 cc. of water, and dissolve in 10 cc. of hydrochloric acid. The solution should not immediately afford a blue color on adding 0.5 cc. of potassium ferrocyanide solution. CALCIUM OXIDE, FROM MARBLE (LIME) CaO. Mol. Wt. 56.1. White pieces of granular structure which develop much heat on being sprinkled with water, and which become con- verted into a fine, dust-like powder, or a pasty mass, according to the quantity of water used. Calcium oxide is soluble in about 800 parts of cold, and in 1300 parts of boiling, water. TESTS OF PURITY Carbonates, Silica, Alumina, and Sulphates. Slake 5 gm. of calcium oxide with 10 cc. of water. The magma so ob- tained should almost completely dissolve in 30 cc. of hydro- chloric acid without strong effervescence. Dilute the solution with 20 cc. of water, and filter. (The insoluble residue, after ignition, should weigh at most 0.005 gm.) To 25 cc. of the filtrate, add barium chloride solution; the liquid should show no change within ten minutes. Supersaturate 25 cc. of the filtrate with ammonia water; the liquid should not be ren- dered more than slightly opalescent. Chlorides. Slake 1 gm. of calcium oxide with 3 cc. of water, dissolve in 10 cc. of nitric acid, dilute the solution with 10 cc. of water, filter, and add silver nitrate solution to the filtrate. The liquid should not be rendered more than slightly opalescent. 84 CHEMICAL REAGENTS CALCIUM PHOSPHATE, DIBASIC (SECONDARY CALCIUM PHOSPHATE; DICALCIUM PHOSPHATE) CaHPO 4 + 2H 2 O. Mol. Wt. 172.14. A white, crystalline powder, easily soluble in hydrochloric, nitric, or phosphoric acid, without effervescence; it is diffi- cultly soluble in water, and in cold acetic acid. Dicalcium phosphate does not dissolve in boiling water without decomposition; it produces a liquid of acid reaction and an amorphous residue, the composition of which approx- imates that of the neutral salt. TESTS OF PURITY Arsenic. The test is carried out as described under Calcium Phosphate, Monobasic on page 85, using a solution of 2 gm. of dicalcium phosphate in 5 cc. of hydrochloric acid and 15 cc. of water Chlorides. Dissolve 1 gm. of dicalcium phosphate in 5 cc. of nitric acid and 15 cc. of water; on adding silver nitrate solution, not more than a slight opalescent turbidity should be visible. Heavy Metals. The solution of 1 gm. of dicalcium phos- phate in 5 cc. of hydrochloric acid and 15 cc. of water should afford a pure white precipitate on the addition of hydrogen sulphide water and 10 cc. of ammonia water. Sulphates. On shaking 1 gm. of dicalcium phosphate with 20 cc. of water and filtering, the nitrate, on adding 1 cc. of hydrochloric acid and barium chloride solution, should develop no precipitate within twelve hours. Residue on Ignition. On ignition, dicalcium phosphate should yield 74 to 75 per cent of its weight of residue.* * Oil ignition, dicalcium phosphate is converted into calcium pyrophos- phate, whereby it theoretically loses 26.12 per cent of water. CHEMICAL REAGENTS 85 CALCIUM PHOSPHATE, MONOBASIC (CALCIUM BIPHOSPHATE ; CALCIUM ACID (OR SUPER) PHOS- PHATE; PRIMARY CALCIUM PHOSPHATE; MONOCALCIUM PHOSPHATE) Ca(H 2 PO 4 ) 2 + H 2 O. Mol. Wt. 252.14. Colorless, pearly scales, which readily deliquesce in the air. Calcium biphosphate dissolves in much water, apparently without decomposition; with a small quantity of water, an amorphous salt separates, richer in calcium, while the solution exhibits a strongly acid reaction. On heating a 1 : 20 aqueous solution of calcium biphosphate to boiling, a precipitate forms. TESTS OF PURITY Arsenic. Introduce 10 gm. of arsenic-free, granulated zinc into the generating flask of a Marsh apparatus, and start the stream of hydrogen by adding dilute (1 : 5) sulphuric acid. After the apparatus and reagents have been tested in the usual manner, dissolve 2 gm. of calcium biphosphate in 5 cc. of hydrochloric acid and 15 cc. of water. Introduce this solution into the Marsh apparatus, and maintain the flow of gas for about one hour. No deposit of arsenic should be visible in the reduction tube within this time. Chlorides. A solution of 1 gm. of calcium biphosphate in 5 cc. of nitric acid and 15 cc. of water should not be ren- dered more than slightly opalescent on the addition of silver nitrate solution. Heavy Metals. On adding hydrogen sulphide water and 10 cc. of ammonia water to a solution of 1 gm. of calcium biphosphate in 5 cc. of hydrochloric acid and 15 cc. of water, a pure white precipitate should form. NOTE. The presence of a small quantity of sulphuric acid in this preparation cannot be avoided. It is due to the customary methods of manufacturing the salt. 86 CHEMICAL REAGENTS CALCIUM PHOSPHATE, TRIBASIC (TERTIARY CALCIUM PHOSPHATE; TRICALCIUM PHOSPHATE) Ca 3 (PO 4 ) 2 . Mol. Wt. 310.3. A white, amorphous powder, insoluble in cold water. Tricalcium phosphate is gradually decomposed by boiling water into an insoluble basic salt and an easily soluble acid salt. It is easily soluble in hydrochloric or nitric acid, and without effervescence. TESTS OF PURITY Arsenic. The test is carried out as detailed under Cal- cium Phosphate, Monobasic, on page 85, using a solution of 2 gm. of tricalcium phosphate in 5 cc. of hydrochloric acid and 15 cc. of water. Sulphates. Shake 1 gm. of tricalcium phosphate with 20 cc. of water, filter, and add to the filtrate 1 cc. of hydro- chloric acid and barium chloride solution. No precipitate should form on standing twelve hours. Chlorides. The solution of 1 gm. of tricalcium phosphate in 5 cc. of nitric acid and 15 cc. of water should not show more than a slight opalescent turbidity on adding silver nitrate solution. Heavy Metals. The solution of 1 gm. of tricalcium phos- phate in 5 cc. of hydrochloric acid and 15 cc. of water should yield a pure white precipitate on adding hydrogen sulphide water and 10 cc. of ammonia water. CALCIUM SULPHATE (GYPSUM) CaSO 4 + 2H 2 O. Mol. Wt. 172.19. A fine, white powder, difficultly soluble in water (about 1:500). CHEMICAL REAGENTS 87 TESTS OF PURITY Iron, Magnesium, and Alkalies. On warming 2 gm. of calcium sulphate with 10 cc. of hydrochloric acid and 100 cc. of water, a clear solution should result, which, on the addi- tion of 15 cc. of ammonia water and a few drops of ammo- nium sulphide solution, should not acquire a greenish or dark color. To the solution, no matter whether a precipitate of calcium sulphate has formed or not, add ammonium oxalate solution in slight excess, filter, evaporate the filtrate, and ignite in a platinum dish. There should not remain a residue weighing more than 0.001 gm. CALCIUM SULPHIDE (SULPHURATED LIME) Light-gray cubes, from which dilute hydrochloric acid sets free copious quantities of hydrogen sulphide gas. TEST OF PURITY Arsenic. This is carried out as detailed under Barium Sulphide on page 72. NOTE. This preparation serves for the generation of arsenic-free hydrogen sulphide. The hydrochloric acid used for this purpose should also be tested for arsenic. CARBON BISULPHIDE CS 2 . Mol. Wt. 76.12. A clear, colorless, neutral liquid of specific gravity 1.270 to 1.272, and boiling at 46 to 47 C. TESTS OF PURITY Non- volatile Matter. On evaporating 50 cc. of carbon disulphide on the water-bath, no weighable residue should remain.* * Under the influence of light, carbon disulphide becomes yellowish, and then leaves a slight residue on evaporation. 88 CHEMICAL REAGENTS Hydrogen Sulphide and Foreign Organic Sulphur Com- pounds. (a) On shaking 10 cc. of carbon disulphide with lead carbonate, the latter should not acquire a brown color. (6) On shaking 2 cc. of carbon disulphide in a dry vessel with a globule of metallic mercury, the bright surface of the latter should not become covered with a dark, pulverulent coating. Sulphuric and Sulphurous Acids. On shaking 10 cc. of carbon disulphide with 5 cc. of water, the latter should neither redden nor decolorize blue litmus paper. CARMINE (CARMINE I. [NACCARAT]) Bright red, light pieces, which are very friable and redu- cible to a fine powder. Carmine is insoluble in water, and in dilute acids, but is soluble in ammonia. TESTS OF PURITY Solubility. 0.15 gm. should be almost completely soluble in a mixture of 5 cc. of ammonia water and 20 cc. of water, yielding a violet-red solution; only a small amount of floc- culent matter should remain undissolved. Ash. 0.25 gm. of carmine cautiously incinerated in a porcelain crucible should not yield an ash weighing more than 0.02 gm. Particular attention should be paid to the odor of the decomposing carmine; it is similar to that yielded during the combustion of proteids. An odor of bromine would point to a sophistication with an eosine-lake; and an odor of phenol would point to an admixture of pseonine-lake. NOTE. Regarding the adulterations of cochineal-carmine, see E. Donath, Dingl. pol. J., 294, 188 (1894); J. Soc. Chem. Ind., 14, 305 (1895). CHEMICAL REAGENTS 89 Regarding the preparation of carmine solutions and carmine tinctures, see Merck's Reagentien-Verzeichnis, p. 171 (1903); Cohn, Tests and Re- agents, p. 349 (1903). Regarding the composition of carmine and of carmine ash, see S. Feitler, Ztschr. angew. Chem., 5, 136 (1892) [or Ztschr. anal. Chem., 32, 627 (1893)]; J. Soc. Chem. Ind., 12, 256 (1893). CHARCOAL, ANIMAL (BLOOD CHARCOAL, PURIFIED BY ACID) A dry, light, black powder. TESTS OF PURITY Material Soluble in Water. Exhaust 1 gm. of animal charcoal by boiling with 20 cc. of water, filter, and evaporate the filtrate to dryness. The residue should not weigh more than 0.003 gm. Material Soluble in Alcohol. Heat a mixture of 1 gm. of animal charcoal and 20 cc. of alcohol to boiling, and filter. The filtrate should leave no weighable residue on evaporation. Sulphates, Chlorides, and Nitrates. (a) Boil 1 gm. of animal charcoal with 50 cc. of water for a few minutes, and filter. The filtrate should be colorless and neutral. On adding to 10 cc. of the filtrate some barium nitrate solution, no immediate turbidity should be produced. (6) On adding silver nitrate solution to 10 cc. of the filtrate, not more than a slight opalescence should develop. (c) On adding 1 drop of 1 : 1000 indigo solution and 5 cc. of concentrated sulphuric acid to 10 cc. of the fil- trate, the blue color of the solution should not dis- appear. Copper, Iron, and Calcium. Boil 1 gm. of animal charcoal with 40 cc. of water and 10 cc. of hydrochloric acid for about 90 CHEMICAL REAGENTS five minutes, filter, and to 10 cc. of the filtrate add 25 cc. of ammonia water; the liquid should not acquire a blue color, nor should a flocculent precipitate form. On the further addition of a few drops of ammonium sulphide and am- monium oxalate solutions, no turbidity should develop immediately. Residue on Ignition. 1 gm. of animal charcoal should leave a residue weighing not more than 0.10 gm. on ignition. Hydrogen Sulphide. Heat 1 gm. of animal charcoal with 40 cc. of water and 10 cc. of hydrochloric acid, and test the escaping vapors with moistened lead acetate paper. The latter should not acquire a brown color. Decolorizing Power. Dissolve 50 gm. of caramel (sugar coloring; burnt sugar) in 50 cc. of water, add 100 cc. of 85 per cent alcohol, dilute the whole to 1 liter, allow to stand for several days, and then filter. Dilute 5 cc. of this caramel solution with 50 cc. of water, add 1 gm. of animal charcoal, boil the mixture ten minutes under a reflux con- denser, and then filter. The filtrate should be perfectly colorless. CHLORINE WATER A clear, pale, greenish-yellow liquid, having a strong odor of chlorine. The liquid should contain about 0.4 per cent of Cl. TESTS OF PURITY Non-volatile Matter. 20 gm. of chlorine water evaporated in a glass dish on a water-bath should leave no weighable residue. Chlorine Content. Let 25 gm. of chlorine water run into a flask containing a solution of 1 gm. of potassium iodide in 25 cc. of water. Add a few drops of starch solution, and titrate the liberated iodine with decinormal sodium thio- sulphate solution, of which at least 28.2 cc. should be used to cause the blue color to disappear. CHEMICAL REAGENTS 91 1 cc. of decinormal Na 2 S 2 3 = 0.003545 gm. of Cl, log. 54962. Hydrochloric Acid.* Shake 20 gm. of chlorine water with about 5 gm. of pure mercury vigorously for five minutes. Filter, add phenolphthalein to the solution, and run in normal potassium hydroxide solution, by drops, until a red color appears. Not more than 0.1 cc. of normal alkali should be required to produce the red end-point. CHLOROFORM CHC1 3 . Mol. Wt. 119.35. A clear, colorless, very volatile liquid, slightly soluble in water (1:200), but miscible in all proportions with alcohol, ether, and fatty and volatile oils. Chloroform has a specific gravity of 1.485 to 1.489, and boils at 60 to 62 C.f TESTS OF PURITY Free Acid. Vigorously shake together 20 cc. of chloro- form and 10 cc. of water for half a minute; after the chloro- form has separated, draw off the aqueous layer with a pipette. The liquid should not redden blue litmus paper, nor should it acquire an opalescence when overlaid on a mixture of 2.5 cc. of water and 2.5 cc. of silver nitrate solution. Free Chlorine. On shaking 5 cc. of chloroform with 5 cc. of zinc iodide-starch solution, the latter should not acquire a blue color, nor should the chloroform become colored. Foreign Organic Bodies. On repeatedly shaking 20 cc. * Chlorine water, unless recently prepared, always contains hydro- chloric acid. fThe readiness of pure (absolute) chloroform to decompose may be prevented by the addition of a small amount (up to 1 per cent) of pure absolute alcohol. The specific gravity and boiling point are somewhat changed by this addition. The alcohol may be removed from the chlo- roform by shaking it twice with double its volume of pure sulphuric acid, neutralizing the acid with granulated potassium carbonate, and distilling. 92 CHEMICAL REAGENTS of chloroform and 15 cc. of concentrated sulphuric acid in a glass-stoppered flask, 3 cm. wide, which has been rinsed previously with sulphuric acid, the acid should not acquire a color within one hour. CHROMIUM TRIOXIDE FREE FROM SULPHURIC ACID ( (ACID) CHROMIC ANHYDRIDE) CrO 3 . Mol. Wt. 100.01. Dark, brownish-red needles, or rhombic prisms, very readily soluble in water. Chromium trioxide contains almost 100 per cent of Cr0 3 . TESTS OF PURITY Sulphuric Acid. 2 gm. of chromium trioxide must afford a clear solution with 20 cc. of water. On adding to the solution 20 cc. of hydrochloric acid and 1 cc. of barium chloride solution, no turbidity should occur immediately. Potassium Sulphate and Potassium Chr ornate. Ignite 0.2 gm. of chromium trioxide in a porcelain crucible, triturate the residue with about 20 cc. of water, and filter. Evapo- rate the filtrate to dryness on a water-bath, dry the residue at 100 C., and weigh. The residue must not weigh more than 0.002 gm. Quantitative Determination. Dissolve 5 gm. of chromium trioxide in water and dilute to 500 cc. Introduce 10 cc. of this solution into a stoppered flask of about 400 cc. capacity, dilute with 100 cc. of water, and add 5 gm. of potassium iodide and 2 cc. of hydrochloric acid. Allow the mixture to stand for about ten minutes with frequent shaking, then dilute with 200 cc. of water, and titrate with decinormal sodium thiosulphate solution. 1 cc. of decinormal Na 2 S 2 3 = 0.003336 gm. of Cr0 3 , log. 52323. CHEMICAL REAGENTS 93 COBALT NITRATE (COBALTOUS NITRATE) Co(NO 3 ) 2 + 6H 2 O. Mol. Wt. 291.17. Red, monoclinic prisms, deliquescent in moist air, and readily soluble in water and in alcohol. TESTS OF PURITY Sulphates. A solution of 1 gm. of cobalt nitrate in 20 cc. of water, to which have been added 0.5 cc. of hydro- chloric acid and a little barium chloride solution, should not become turbid. Alkali Salts. Precipitate the cobalt completely from a solution of 2 gm. of cobalt nitrate in 100 cc. of water by adding ammonia water and ammonium sulphide solution; filter, evaporate the filtrate to dryness, and ignite the residue. The weight of the latter should not -exceed 0.005 gm. Zinc. To a solution of 0.5 gm. of cobalt nitrate in 50 cc. of water, add 5 cc. of sodium hydroxide solution (sp. gr. 1.3); filter, and to the filtrate add ammonium sulphide solution. No precipitate should form. Lead and Copper. Dissolve 2 gm. of cobalt nitrate in 50 cc. of water, and add 2 cc. of nitric acid, followed by hydrogen sulphide water. The solution must show no change. Nickel.* Dissolve 1 gm. of cobalt nitrate in 20 cc. of water, add 3 gm. of potassium cyanide, boil the solution until it has acquired a yellow color, filter, and to the filtrate add potassium hydroxide solution and bromine water. No brown color should develop. * Compare the method using nitrosobeta-naphthol. See Prescott and Johnson, Qualitative Chemical Analysis, p. 166 (1901). 94 CHEMICAL REAGENTS COLLODION A colorless, or slightly yellowish, neutral, syrupy liquid, which, exposed in thin layers, evaporates, and leaves a tough, colorless film. Collodion contains about 4 per cent of soluble cotton. TESTS OF PURITY Acids. Blue litmus paper, when immersed in collodion, should not be reddened immediately. Determination of Residue. On evaporating 10 gm. of collodion on the water-bath, it should leave a residue, which, when dried at 100 C., should weigh 0.38 to 0.40 gm. COPPER, BY ELECTROLYSIS Cu. Atomic Wt. 63.6. / TESTS OF PURITY Foreign Metals. (ft) Dissolve 10 gm. of copper in 60 cc. of nitric acid (sp. gr. 1.3), and evaporate the solution to dryness on the water-bath. The residue should completely dis- solve in 50 cc. of water and 10 cc. of nitric acid (sp. gr. 1.3), yielding a clear solution (absence of antimony and tin). To the solution add 15 cc. of concentrated sulphuric acid (sp. gr. 1.84), evaporate on the water-bath as far as possible, heat the residue on a sand-bath until vapors of sulphuric acid begin to be evolved, and take up the residue with 100 cc. of water. No insoluble residue should remain (absence of lead). On adding 5 cc. of hydrochloric acid to the clear solution, no turbidity should ensue (absence of silver). Now add 150 cc. of ammonia water to the liquid, allow to stand three to four he '.TS at 50 to 60 C. ; filter through an ashless filter, CHEMICAL REAGENTS 95 wash with ammoniacal water until perfectly free from copper. Incinerate the filter with any pre- cipitate it may contain, and ignite. The residue should not weigh more than 0.001 gm. (iron and bismuth). (6) Dissolve 10 gm. of copper in 60 cc. of nitric acid (sp. gr. 1.3), add to the solution 15 cc. of concentrated sulphuric acid (sp. gr. 1.84), evaporate the solution on the water-bath as far as possible, and heat the residue on a sand-bath until the vapors of sulphuric acid begin to be evolved. Dissolve the residue in 300 cc. of water, pass hydrogen sulphide gas into the solution at 70 C. until the copper is completely precipitated, filter, concentrate the filtrate, expel the sulphuric acid on the sand-bath, and ignite the residue. The weight of the latter should not exceed 0.002 gm. Arsenic. Dissolve 10 gm. of copper in 60 cc. of nitric acid (sp. gr. 1.3), add to the solution 15 cc. of concentrated sulphuric acid (sp. gr. 1.84), evaporate the solution on the water-bath as far as possible, and then heat the residue on the sand-bath until vapors of sulphuric acid are evolved. When cold, dissolve the residue in 100 cc. of water. Set a Marsh apparatus in operation, using 50 gm. of arsenic- free, granulated zinc, and dilute (1 : 5) sulphuric acid, then introduce the copper sulphate solution in small quantities at a time, and maintain the flow of gas for about two hours. No deposit of arsenic should be visible in the reduction tube within this time. 96 CHEMICAL REAGENTS COPPER CHLORIDE, CUPRIC (COPPER BICHLORIDE) CuCl 2 + 2H 2 O. Mol. Wt. 170.53. Green, hygroscopic crystals, easily soluble in water, alcohol, and ether. TESTS OF PURITY Substances Insoluble in Alcohol. The solution of 5 gm. of copper chloride in 5 cc. of water should not be rendered turbid on mixing with 5 cc. of 95 per cent alcohol. Sulphates. Dissolve 1 gm. of copper chloride in 20 cc. of water, and add 0.5 cc. of hydrochloric acid, followed by barium chloride solution. No turbidity should ensue within five minutes. Salts of Alkali Metals. Dissolve 3 gm. of copper chloride in 100 cc. of water, add 5 cc. of hydrochloric acid, and into the solution, maintained at about 70 C., pass hydrogen sulphide gas, until the copper is completely precipitated; filter, evaporate the filtrate to dryness, and ignite the residue. The weight of the latter should not exceed 0.002 gm. Iron. The test is carried out as described under Copper and Ammonium Chloride. Arsenic. Introduce 20 gm. of arsenic-free, metallic zinc into the generating flask of a Marsh apparatus, and start the hydrogen by adding dilute (1:5) sulphuric acid. Dis- solve 1 gm. of copper chloride in 20 cc. of water, introduce the solution in small quantities at a time into the Marsh apparatus, and maintain a slow stream of gas for about one hour. No deposit of arsenic should be visible in the reduction tube of the apparatus within this time. CHEMICAL REAGENTS 97 COPPER CHLORIDE, CUPROUS (COPPER MONOCHLORIDE) Cu 2 Cl 2 . Mol. Wt. 198.1. A white, crystalline powder, insoluble in water, but soluble in concentrated hydrochloric acid and in ammonia water. The quality of cuprous chloride may be judged from its appearance. The preparation should be white, but not green nor brown.* Both the hydrochloric acid and the ammoniacal solutions should rapidly and freely absorb carbon monoxide. COPPER OXIDE (CupRic OXIDE) CuO. Mol. Wt. 79.6. Copper oxide is used in ultimate organic analysis, in the form of fine powder or coarse granules, and also in the form of wire. TESTS OF PURITY Nitrates, Chlorides, and Carbon Dioxide. On heating 100 gm. of copper oxide, and passing over it a stream of moist air freed from carbonic acid, no vapors should be given off which redden litmus paper, or render. lime water turbid. Substances not Precipitated by Hydrogen Sulphide (Iron, etc.). Dissolve 2 gm. of copper oxide in 10 cc. of hydro- chloric acid (sp. gr. 1.19), dilute with water to 100 cc.; ignite the insoluble residue, the weight of which should not exceed 0.005 gm. Pass hydrogen sulphide gas into the solution at about 70 C., until the copper has completely precipitated, filter, evaporate the filtrate on the water-bath, and ignite the residue. The weight of the latter should not exceed 0.02 gm. Sulphates. Dissolve 1 gm. of copper oxide in 5 cc. of * Cuprous chloride soon acquires a green color in air. 98 CHEMICAL REAGENTS hydrochloric acid (sp. gr. 1.19), dilute with water to 50 cc., and add barium chloride solution. No immediate turbidity should appear. Calcium. Digest 20 gm. of copper oxide with a mixture of 5 cc. of nitric acid and 95 cc. of water for about fifteen minutes, shaking frequently; filter, precipitate the copper in the filtrate completely by passing hydrogen sulphide gas, and filter again. Evaporate the filtrate on the water-bath to about 20 cc., add ammonia water in excess, filter once more, and to the filtrate add ammonium oxalate solution. No immediate turbidity should be produced. COPPER SULPHATE (CuFRic SULPHATE) CuSO 4 4- 5H 2 O. Mol. Wt. 249.74. Blue, transparent crystals, slightly efflorescent in dry air, soluble in 3.5 parts of cold, and in 1 part of boiling, water; insoluble in alcohol. The aqueous solution is acid to litmus paper. TESTS OF PURITY Salts of the Alkalis, Earths, etc. Dissolve 3 gm. of copper sulphate in 100 cc. of water, add 5 cc. of hydrochloric acid, and into the solution, maintained at about 70 C., pass hydrogen sulphide gas until the copper is completely precipi- tated. On evaporating the filtrate to dry ness, and igniting the residue, the weight of the latter should not exceed 0.001 gm. Iron. To the solution of 5 gm. of copper sulphate in 25 cc. of water, add 2 cc. of nitric acid (sp. gr. 1.3), and heat the mixture to boiling. Then add 20 cc. of ammonia water, pour the liquid through an ashless filter, wash the latter with ammoniacal water until perfectly free from copper, and then incinerate and ignite the filter together CHEMICAL REAGENTS 99 with any precipitate it may contain. The weight of the residue should not exceed 0.001 gm. COPPER AND AMMONIUM CHLORIDE (AMMONio-CupRic CHLORIDE) CuClo 2(NH 4 C1) + 2H 2 O. Mol. Wt. 277.57. Blue crystals, giving with water a clear solution slightly acid to litmus paper. TESTS OF PURITY Free Acids. A solution of 30 gm. of copper and ammo- nium chloride in 100 cc. of water must be perfectly clear. On introducing into the solution several pieces of piano wire, the latter should dissolve with the deposition of copper, but without any evolution of gas. Sulphates. Dissolve 1 gm. of copper and ammonium chloride in 20 cc. of water, and add 0.5 cc. of hydrochloric acid, followed by barium chloride solution. No turbidity should be produced within five minutes. Salts of the Alkalis, Earths, etc. Dissolve 3 gm. of copper and ammonium chloride in about 100 cc. of water, add 5 cc. of hydrochloric acid, pass hydrogen sulphide gas into the solution at about 70 C., until the copper is completely precipitated; filter, evaporate the filtrate, and ignite the residue. The weight of the latter should not exceed 0.002 gm. Iron. Dissolve 5 gm. of copper and ammonium chloride in 25 cc. of water, add 2 cc. of nitric acid (sp. gr. 1.3), heat to boiling, then add 20 cc. of ammonia water and pour the liquid through an ashless filter. Wash the latter with ammoniacal water until perfectly free from copper; incin- erate and ignite the filter together with any precipitate it may contain. The weight of the. residue should not exceed 0.002 gm. 100 CHEMICAL REAGENTS DIPHENYLAMINE* (C 6 H 5 ) 2 NH. Mol. Wt. 169.12. White, monoclinic crystals, insoluble in water, but easily soluble in alcohol, ether, and benzene. Diphenylamine melts at 54 C. and boils at 302 C. TESTS OF PURITY Nitric Acid. 0.2 gm. of diphenylamine should dissolve in 20 cc. of pure concentrated sulphuric acid with 2 cc. of water, and yield a colorless solution. Should a blue color develop, the sulphuric acid should be tested with brucine for the possible presence of nitric acid. Aniline. On pouring 1 gm. of powdered diphenylamine into 20 cc. of a chlorinated lime solution, the liquid should not acquire a violet color. * The diphenylamine solution, used as a reagent, is prepared by dis- solving 0.5 gm. of diphenylamine in 100 cc. of pure, concentrated sulphuric acid (free from nitric acid) and 20 cc. of water. According to G. Lunge [Ztschr. angew. Chem., 7, 345 (1894); J. Chem. Soc., 66, II, 398 (1894)], the reagent is employed as follows: To test for nitric or nitrous acid, introduce about 5 cc. of the reagent solution into a test tube, and overlay it with the liquid to be examined. If the latter is specifically heavier than the reagent solution, the dipheny- lamine solution is to be overlaid upon the liquid. Regarding the increased sensitiveness of the nitric-acid reaction with diphenylamine in water analyses, see R. Cimmino, Ztschr. anal. Chem., 38, 429 (1899); J. Chem. Soc., 70, II, 805 (1899). CHEMICAL REAGENTS 101 ETHER (ETHYL ETHER) (C 2 H 5 ) 2 O. Mol. Wt. 74.08. I ETHER, SP. GR. 0.720 A clear, colorless, mobile liquid of specific gravity 0.720,* boiling at 34 to 36 C. Ether should not redden moist blue litmus paper. Filter paper which has been moistened with ether should have no odor when dry. TESTS OF PURITY Residue. On allowing 20 cc. of ether to evaporate spon- taneously in a glass dish, the residue must have no odor, and should not redden or decolorize blue litmus paper; and it must be completely volatilized on warming on the water- bath. Ethyl Peroxide, Hydrogen Peroxide, and Ozone. On vig- orously shaking 10 cc. of ether with 1 cc. of 1 : 10 aqueous potassium iodide solution in a completely filled glass-stop- pered bottle, neither the ether nor the potassium iodide solution should acquire a color after standing one hour in the dark. Aldehydes. On covering pieces of potassium hydroxide the size of a pea with the ether, and setting aside in the dark for one half hour, the liquid must not acquire a yellow color. Sulphur Compounds. On shaking 20 cc. of ether with a globule of mercury for two minutes in a glass-stoppered * It must be remembered that ether is apt to absorb moisture from the air, particularly when poured from one vessel into another, acquiring in consequence a higher specific gravity. 102 - CHEMICAL REAGENTS bottle, the bright surface of the metal must not be tarnished; nor should a black precipitate form. Water. On shaking 20 cc. of ether in a stoppered flask with 1 gm. of anhydrous copper sulphate, the latter should not acquire a green or blue color. II ETHER, ANHYDROUS, DISTILLED OVER SODIUM TESTS OF PURITY In addition to the tests given above, this preparation must answer the following requirement : On introducing 15 cc. of ether into a dry, glass-stoppered flask with a freshly-cut piece of sodium the size of a pea, only a very slight evolution of gas should take place, and the bright metallic surfaces of the sodium should not com- pletely lose their luster within six hours. FURFURAL (FURFUROL) C 5 H 4 O 2 . Mol. Wt. 96.03. When freshly prepared, furfural is a clear, colorless liquid, which rapidly acquires a yellow color on exposure to light and air. Furfural has a specific gravity of 1.165 to 1.166, boils at 158 to 160 C., and is soluble in 12 parts of cold water. It is very easily soluble in alcohol and in ether. NOTE. Regarding the quantitative determination of furfural, see W. E. Stone, Ztschr. anal. Chem., 40, 550 (1901); J. Anal. Appl. Chem., 5, 421 (1895). W. Cormack, Ztschr. anal. Chem., 43, 256 (1904); J. Chem. Soc., 77, 990 (1900). Merck's Reagentien-Verzeichnis, p. 19 (1903); Lewkowitsch, Chem. Technol. and Anal. Oils, Fats, and Waxes, 3 ed.. Vol. II, p. 542 (1904). Merck's Reagentien-Verzeichnis, pp. 129, 157 (1903); H. Schiff, J. Chem. Soc., 52, 571 (1887). Weltering, Pharm. Ztschr. f. Russl., 31, 526 [Ztschr. anal. Chem., 36, 410 (1897)]. CHEMICAL REAGENTS 103 GALLEIN, LIQUID (GALLEIN) A pale brown coloring matter, consisting of pyrogal- lolphthalein. Gallein in alcoholic solution is used as an indicator. GLYCERIN (GLYCEROL) C 3 H 8 3 . Mol. Wt. 92.06. I GLYCERIN, SP. GR. 1.250 A clear, colorless, odorless liquid, neutral in reaction, soluble in all proportions in water and in alcohol. Insoluble in ether and chloroform. Specific gravity not less than 1.250. It contains at least 95 per cent of absolute glycerin, C 3 H 8 3 . TESTS OF PURITY Arsenic. On mixing 1 cc. of glycerin with 3 cc. of stan- nous chloride solution, the mixture should not darken within one hour. Free Acids and Bases. On diluting 10 cc. of glycerin with 50 cc. of water, the solution should not affect red or blue litmus paper. Inorganic Matter. On boiling 5 cc. of glycerin in an open dish and then gently igniting, the glycerol should be vola- tilized completely, leaving only a dark stain which should disappear on being more strongly heated. Substances which Reduce Ammoniacal Silver Nitrate Solu- tion. On heating a mixture of 1 cc. of glycerin and 1 cc. of ammonia water on the water - bath to 60 C., and then immediately adding 3 drops Of silver nitrate solution, neither 104 CHEMICAL REAGENTS a coloration nor a brownish-black precipitate should develop within five minutes. Fatty Acids. On gently warming 1 cc. of glycerin with 1 cc. of 16 per cent sulphuric acid, no unpleasant, rancid odor should develop. Hydrochloric Acid (Chlorides). 5 cc. of glycerin diluted with 25 cc. of water should exhibit at most a slight, opa- lescent turbidity on the addition of silver nitrate solu- tion. Sulphuric and Oxalic Acids. The solution of 5 gm. of glycerin in 25 cc. of water should not be affected by barium chloride solution nor by calcium chloride solution. Heavy Metals. On diluting 5 cc. of glycerin with 25 cc. of water and adding hydrogen sulphide water, no change should appear. Calcium. 5 cc. of glycerin dissolved in 25 cc. of water should not be affected by the addition of ammonium oxalate solution. Sugars. 5 cc. of glycerin are mixed with 50 cc. of water and a few drops of hydrochloric acid, heated thirty minutes on a water-bath, then 10 cc. of the hot liquid are made alka- line with sodium hydroxide and mixed with 1 cc. of Fehling's solution. No yellowish-red cloud or precipitate should appear within six hours. Readily Carbonizable Matter. 5 cc. of glycerin mixed with an equal volume of concentrated sulphuric acid, and allowed to stand one hour, should not become darker than yellow. II GLYCERIN, SP. GR. 1.23 A clear, colorless, odorless liquid of neutral reaction. Its specific gravity is 1.225-1.235. CHEMICAL REAGENTS 105 TESTS OF PURITY The tests for arsenic, heavy metals, chlorides, substances which reduce ammoniacal silver nitrate, free acids and bases, oxalic, sulphuric and fatty acids, and inorganic matter, are to be made in the manner described under Glycerin, sp. gr. 1.250. The following additional test is also to be made: Ammonium Compounds and Organic Bodies Such as Occur in Unpurified Glycerin. On heating 1 cc. of glycerin with 1 cc. of sodium hydroxide solution, no ammonia should be evolved (to be detected by means of moistened litmus paper) ; nor should a color develop nor an odor resembling that of glue. GUAIACIN ACCORDING TO SCHMITT* Guaiacin is a brownish, amorphous powder, obtained by a special method from guaiac wood. It is soluble in alcohol, is colored blue by oxidizers, is far more sensitive than guaiac resin, and serves as an excellent reagent for oxidases. Guai- acin is used in the form of a 5 per cent alcoholic solution, which keeps well in completely filled, dark-colored, well- stoppered bottles. HEMATEIN Ci6H 12 O 6 . Mol. Wt. 300.09. Hematein occurs in reddish-brown plates, presenting a yellowish-green metallic luster. 100 parts of water at 20 C. dissolve 0.06 part of hematein. It is difficultly soluble in ether and in alcohol, and insoluble in chloroform and benzene ; but it is soluble in ammonia water with brownish-violet * Le Bois de Gajac, These de Nancy. 1875. Report on the Advance- ments of Pharmaceutical Chemistry and Therapeutics, E. Merck, p. 73, 1902. 106 CHEMICAL REAGENTS color, and in dilute sodium hydroxide solution, producing a bright-red color. HEMATOXYLIN e + 3H 2 O. Mol. Wt. 356.16. Colorless, or pale-yellow, tetragonal prisms, melting at 100 to 120 C. with loss of water. On slowly cooling a solu- tion saturated at boiling heat, hematoxylin crystallizes at times in the form of rhombic crystals containing one mole- cule of water of crystallization. Hematoxylin is but slightly soluble in cold water and in ether, but is more soluble in borax solution and in hot water, and is easily soluble in alcohol. On exposure to light it gradually acquires a red color, and then dissolves to form yellow solutions. In ammonia water hematoxylin dissolves and yields a purple solution. Hematoxylin is used as an indicator in 0.5 per cent alcoholic solution. NOTE. Regarding the use of hematoxylin as an indicator in the titration of alkaloids, see C. Kippenberger, Ztschr. anal. Chem., 39, 201 (1900); J. Chem. Soc., 78, II, 637 (1900). J. Messner, Ztschr. angew. Chem., 16, 444 (1903); J. Chem. Soc., 84, II, 519 (1903). HIDE POWDER White or yellowish- white, woolly powder, prepared from the best quality of hide from which the hair has been re- moved with lime and which has been thoroughly washed. Hide powder should have but a slight odor and should be specially free from odors of decomposition products. It is used for tannin determination. TEST OF PURITY Determination of the Water-Soluble Constituents.* In- * As the quantity of water-soluble constituents in the various hide powders varies greatly, it is always necessary, before using a hide powder for tannin determinations, to determine the quantity of soluble constit- uents by a blank test according to the method described here. 2 0.003336 0.0017008 52323 23065 Iodine I 012697 10369 Iron Fe 00559 74741 Potassium Biniodate KIO 3 -HIO 3 0.00325082 51199 Potassium Bromate KBrO 3 0.00278516 44485 Potassium Chromate K 2 CrO4 00648 81158 Potassium Dichromate K 2 Cr 2 O7 0049083 69092 Potassium lodate KIO 3 0035686 55250 Sodium Bromate NaBrO 3 0.002517 40089 1 CC. OF DECINORMAL IODINE SOLUTION IS THE EQUIVALENT OF : Gram. Log. Acid Arsenous As2O 3 00495 69461 Acid Sulphurous SO 2 . 003203 50556 Iron Sulphide FeS 004398 64326 Potassium Bisulphite KHSOa 0060105 77887 Sodium Bisulphite NaHSO 3 0052059 71649 Sodium Sulphide Na2S + 9 H 2 O 00120152 07972 Sodium Sulphite, Cryst. Na 2 SO 3 + 7H 2 O 0126136 10084 Sodium Sulphite, Anhydrous Na^SOs ... 006308 79989 Sodium Thiosulphate Na^Os + 5H 2 O 02483 39498 Stannous Chloride SnCl 2 + 2 H 2 O 00112966 05294 CHEMICAL REAGENTS 241 1 CC. OF FIFTH-NORMAL HYDROCHLORIC ACID IS THE EQUIVALENT OF : Gram. Log. Sodium Borate Cryst * Na2B 4 O7 + lOHgO 038226 58235 Sodium Borate Anhydrous *Na2B4O? .... 02021 30557 Sodium Oxalate (after ignition) Na2C2O4 0.01341 12743 * Indicator : Methyl Orange. 1 CC. OF FIFTH-NORMAL POTASSIUM HYDROXIDE SOLUTION IS THE EQUIVALENT OF : Gram. Log. Acid Oxalic Cryst H2C2O4 + 2ELO .... 012605 10055 Acid Oxalic Anhydrous H^C2O4 0.009001 95432 Potassium Biniodate * KIOa-HIOa 0.078018 89219 Potassium Tetraoxalate *KHC 2 O 4 + B 2 C 2 O4 + 2H 2 O. . 0.016947 22909 * Indicator: Phenolphthalein. INDEX Acetone, 1. Acetic Acid, 2, 3, 4, 5. Anhydride, 5. Acid Acetic, 2, 3, 4, 5. Anhydride, 5. Diluted, 30 per cent, 4. Glacial, 96 per cent, 3. 36 per cent, 4. 90 per cent, 4. 99^ per cent, 2. Alphanaphthylaminesulphonic , 20. Arsenous, 65. Arsenous Anhydride, 65. Boric Anhydride, 5. Fused, 5. . Carminic, 6. Chlorplatinic, 149. Chromic Anhydride, 92. Citric, 7. Fluosilicic, 16. Gallic, 8. Hydriodic, 9, 10. Sp. Gr. 1.5, 9. Sp. Gr. 1.7, 10. Hydrobromic, 10. Hydrochloric, 12, 14, 15. See Preliminary Note. Concentrated, 12. Diluted, 14. Fuming, 12. Sp. Gr. 1.050, 15. Sp. Gr. 1.124, 14. Acid Hydrochloric Sp. Gr. 1.19, 12. Hydrofluoric, 15. Hydrosilicofluoric, 16. lodic, 17. Anhydride, 18. Molybdic, 18. Anhydride, 18. 100 per cent, 18. Naphthionic, 20. Naphthylaminesulphonic, 20. Nitric, 20, 21, 22. See Pre- liminary Note. Crude, 22. Fuming, 22. Sp. Gr. 1.40, 20. Sp. Gr. 1.20, 22. Sp. Gr. 1.30, 21. Sp. Gr. 1.153, 22. Oxalic, 23. Sublimed, 25. Perchloric, 25. Phosphomolybdic, 26. Phosphoric, 26, 28, 29. Anhydride, 29. Sp. Gr. 1. 12, 28. Sp. Gr. 1.057, 29. Sp. Gr. 1.7, 26. Glacial, 29. Ortho, 26, 28, 29. Meta, 29. Phosphotungstic, 30. Picric, 31. Picronitric, 31. Pyrogallic, 185. Rosolic, 32. 243 244 INDEX Acid Silicofluoric, 16. Succinic, 33. Sulphanilic, 34. Sulphuric, 34, 36, 37. Anhydride, 37. Concentrated, 34. Diluted, 16 per cent, 36. Fuming, 38, 39. Fuming, Free from Nitrogen, 38. Fuming, with Phos- phoric Anhydride, 41. Sp. Gr. 1.84, 34. with Phosphoric Anhydride, 40. 10 per cent, 37. Sulphurous, 41. Cubes for Gener- ating, 42. Tannic, 42. Tartaric, 43. Thioacetic, 44. Alcohol, 44, 46. . Absolute, 44. 85 per cent, 46. 95 per cent, 46. Amyl, for Gerber's Fat De- termination, 47. Amylic, 47. Ethylic, 44, 46. Methylic, 48. Alphanaphthol, 49. Aluminum Oxide, 49. Ammonia Water, 50, 51, 52. See Preliminary Note. Concentrated, 51. Stronger, 50. 10 per cent, 52. 20 per cent, 51. 28 per cent, 50. Ammonio-Cupric Chloride, 99. Ammonio-Ferric Alum, 122. Ammonium Acetate. 53. Carbonate, 53. Chloride, 54. Citrate Solution, 55. Dithiocarbonate Solution, 56. Fluoride, 56. Molybdate, 57. Nitrate, 58. Oxalate, 59. Phosphate, 59. Sulphate, 61. Sulphide Solution, 62. Sulphocyanate, 61. Sulphydrate Solution, 62. Thioacetate Solution, 63. Thiocyanate, 61. Amyl Alcohol, 47. for Gerber's Fat De- termination,- 47. Aniline, 63. Animal Charcoal, 89. Antimonous Oxide, 64. Antimony Oxide, 64. Trioxide, 64. Apparatus, Marsh. See Preliminary Note. Arsenic Trioxide, 65. Arsenous Anhydride, 65. Atomic Weights, 238. See Prelimi- nary Note. Azolitmin, 66. Barium Acetate, 66. Carbonate, 67. Chloride, 68. Dioxide, 69. Hydrate, 70. Hydroxide, 70. Solution, 71. Nitrate, 71. Peroxide, 69. Sulphide, 72. Superoxide, 69. Baryta Water, 71. INDEX 245 Benzene, 72. Benzidine, 73. Benzin, 74. Petroleum, 74. Benzol, 72. Bismuth Nitrate, Basic, 74. Subnitrate, 74. Blood Charcoal, 89. Borax, 193, 194, 195, 196. Anhydrous, 196. Glass, 196. Boric Anhydride, 5. Boron Trioxide, 5. Bromine, 76. Water, 77. Brucine, 77. Cadmium and Potassium Iodide-, 78. Borotungstate Solution, 78. Calcium Biphosphate, 85. Carbonate Precipitated, 79, Chloride, Crystals, 80. Dry Granulated, 81. Fused, 82. Hydroxide, 82. Solution, 131. Oxide, from Iceland Spar, 82. Marble, 83. Phosphate, Acid, 85. Dibasic, 84. Monobasic, 85. Primary, 85. Secondary, 84. Super, 85. Tertiary, 86. Tribasic, 86. Sulphate, 86. Sulphide, 87. Carbon Disulphide, 87. Carmine, 88. I (Naccarat), 88. Caustic Potash, 167, 168, 170, 171. Soda, 202, 204, 205. Caustic Soda Solutions, 207. Charcoal, Animal, 89. Blood, 89. Chlorinated Lime, 130. Chlorine Water, 90. Chloroform, 91. Chromic Anhydride, 92. Chromium Trioxide, 92. Cobalt Nitrate, 93. Cobaltous Nitrate, 93. Collodion, 94. Concentrated Hydrochloric Acid, 12. Sulphuric Acid, 34.- Copper and Ammonium Chloride, 99. by Electrolysis, 94. Chloride, Cupric, 96. Cuprous, 97. Dichloride, 96. Monochloride, 97. Oxide, 97. Sulphate, 98. Corallin, 32. Corrosive Sublimate, 140. Cubes for Generating Sulphurous Acid, 42. Cupric Chloride, 96. Oxide, 97. Sulphate, 98. Cuprous Chloride, 97. Dibasic Calcium Phosphate, 84. Di calcium Phosphate, 84. Diphenylamine, 100. Disodium Hydrogen Phosphate, 217. Distilled Water, 229. Ether, 101, 102. Anhydrous, Distilled over So- dium, 102. Sp. Gr. 0.720, 101. Petrolic, 74. Ethyl Alcohol, 44, 46. 246 INDEX Ethyl Ether, 101, 102. Ferric Ammonium Sulphate, 122. Chloride, 118. Ferrous Ammonium Sulphate, 123. Chloride, 119. Sulphate, 120. Sulphide, 121. Fuming Sulphuric Acid, 38, 39. Furfural, 102. Furfurol, 102. Gallein, 103. Liquid, 103. Glycerin 103, 104. Sp. Gr. 1.250, 103. Sp. Gr. 1.23, 104. Glycerol, 103, 104. Guaiacin, according to Schmitt, 105. Gypsum, 86. Hematein, 105. Hematoxylin, 106. Hide Powder, 106. Hydriodic Acid, 9, 10. Hydrochloric Acid, 12, 14, 15. See Preliminary Note. Hydrogen Dioxide, 107. Peroxide, 30 per cent, 107. Sulphide Water, 109. Hydroxylamine Hydrochloride, 109. Indigo, 110, 111. Blue, 111. Synthetic, 110. Vegetable, 111. Indigotin, 111. lodeosin, 112. lodic Anhydride, 18. Iodine, 113. Pentoxide, 18. Resublimed, 113. Water, 114. Iron, 114, 115, 117. Iron and Ammonium Sulphate, Fer- ric, 122. and Ammonium Sulphate, Fer- rous, 123. by Hydrogen, 115. Chloride, Ferric, 118. Ferric, Solution, 119. Ferrous, 119. Powder, 117. Reduced, 115. Sulphate, Ferrous, 120. Sulphide, 121. Wire, 114. Kassner's Mixture, 143. Lacmoid, 124. Lead Acetate, 125. Chromate, 126. Dioxide, 126, 128. Oxide, Brown, 126, 128. Brown, Free from Man- ganese, 126. Brown, for Dennstedt's Analysis, 128. Yellow, 129. Peroxide, 126, 128. Subacetate Solution, 130. Superoxide, 126, 128. Lime, 83. Chlorinated, 130. Slaked, 82. Sulphurated, 87. Water, 131. Litharge, 129. Litmus, 131. Magnesia, 134, 136. Magnesium and Ammonium Chlo- ride, 137. Carbonate, 132. Chloride, 133. Oxide, 134, 136. Free from Sulphates, 136. INDEX 247 Magnesium Sulphate, 136. Manganese Chloride, 137. Dioxide, 138. Peroxide, 138, Sulphate, 139. Superoxide, 138. Manganous Chloride, 137. Sulphate, 139. Marignac's Salt, 180. Marsh Apparatus. See Preliminary Note. Mercuric Chloride, 140. Oxide, 141. Potassium Iodide, 142. Mercurous Nitrate, 141. Mercury, 140. and Potassium Iodide, 142. Bichloride, 140. Nitrate, 141. Oxide, Red and Yellow, 141. Metadiaminobenzene Hydrochlo- ride, 142. Metaphenylenediamine Hydrochlo- ride, 142. Metaphosphoric Acid, 29. Methyl Alcohol, 48. Orange, 143. Microcosmic Salt, 223. Mixture, Kassner's, 143. Mohr's Salt, 123. Molybdic Anhydride, 18. Monobasic Calcium Phosphate, 85. Monocalcium Phosphate, 85. Nitric Acid, 20, 21, 22. See Pre- liminary Note. Nitrobenzaldehyde, Ortho, 143. Nitron, 144. Nitrophenol, Ortho, 144. Para, 144. Nitrosobetanaphthol, 145. Orthonitrobenzaldehyde, 143. Orthonitrophenol, 144. Palladium, 145. and Sodium Chloride, 146. Chloride, 146. Nitrate, 146. Palladous Chloride, 146. Nitrate, 146. Paradiaminodiphenyl, 73. Paranitrophenol, 144. Perhydrol, 107. Petroleum Ether, 74. Phenacetolin, 146. Phenolphthalein, 147. Phenylhydrazine, 147. Phloroglucin, 148. Phosphoric Acid, 26, 28, 29. Anhydride, 29. Phosphorous Pentoxide, 29. Piano Wire, 114. Platinic Chloride, 149. Platinum, 148. Chloride, 149. Potassium Acetate Solution, 150. Acid Pyroantimonate, 151. Acid Sulphate, 155. Acid Sulphite, 155. Acid Tartrate, 156. and Cadmium Iodide, 78. and Sodium Tartrate, 184. Antimonate, 151. Bicarbonate, 151. Bichromate, 164. Biniodate, 153. Bisulphate, 155. Bisulphite, 155. Bitartrate, 156. Bromate, 158. Bromide, 158. Carbonate, 159. Solution, 161. Chlorate, 161. Chloride, 162. Chromate, 163. Chromate, Yellow, 163. Cyanide, 164. 248 INDEX Potassium Dichromate, 164. Ferri cyanide, 165. Ferrocyanide, 166. Hydrate, 167, 168, 170, 171. Hydrosulphide, 183. Hydroxide, 167, 168, 170, 171. Purest, 168. Purified, 171. Purified by Alco- hol, 170. Solutions, 172. lodate, 173. Iodide, 173, 175. Neutral, 175. Nitrate, 175. Nitrite, 176. Oxalate, Neutral, 177. Perchlorate, 178. Permanganate, 179, 180. Permanganate, Free from Sul- phates, 180. Stannosulphate, 180. Sulphate, 181. Sulphide, 181. Solution, 181. Sulphocyanate, 182. Sulphydrate, 183. Tetraoxalate, 183. Thiocyanate, 182. Primary Calcium Phosphate, 85. Prussiate of Potash, Red, 165. Yellow, 166. Pyrogallol, 185. Pyrolusite, 138. Red Prussiate of Potash, 165. Reduced Iron, 115. Residue Unweighable. See Pre- liminary Note. Resorcin, 185. Resorcinol, 185. Blue, 124. Rochelle Salt, 184. Schiff's Reagent, 63. Secondary Calcium Phosphate, 84. Sodium Phosphate, 217. Seignette Salt, 184. Silver, 186. Nitrate, 186. Nitrite, 187. Slaked Lime, 82. Soda Lime, 208, 209. Sodium, 188. Acetate, 189. Acid Sulphate, 192. Acid Sulphite, 192. Amalgam, 189. and Ammonium Phosphate, 223. and Potassium Carbonate, 223. Biborate, 193, 194. Bicarbonate, 190. Bisulphate, 192. Bisulphite, 192. Borate, 193, 194, 195, 196. Purest, Calcined, 195. Crystals, 194. Fused, 196. Bromate, 196. Carbonate, 197, 199, 200. Anhydrous, 200. Crystals, 197. Dried, 199. Chloride, 200, 201. Fused, 201. Hydrate, 202, 204, 205. Hydroxide, 202, 204, 205. from Sodium, 202. Purified, 205. Purified by Alco- hol, 204. Solutions, 207. Solution I, 207. Solution II, 207. Solution III, 207. with Lime, 208, 209. INDEX 249 Sodium Hydroxide, with Lime, from Iceland Spar, 209. Hyposulphite, 221. Nitrate, 209. ' Nitrite, 211, 212. Free from Potassium, 212. Nitroferricyanide, 212. Nitroprusside, 212. Oxalate, 213. Palladous Chloride, 146. Peroxide, 215. Phosphate, 217. Secondary, 217. Pyrophosphate, 218. Sulphate, 219. Sulphide, 219. Solution, 220. Sulphite Crystals, 221. Dried, 221. Superoxide, 215. Tetraborate, 193, 194. Thiosulphate, 221. Tungstate, 222. Wolframate, 222. Solution Ammonium Citrate, 55. Dithiocarbo- nate, 56. Sulphide, 62. Sulphydrate, 62 Thioacetate, 63. Barium Hydroxide, 71. Cadmium Borotungstate, 78. Calcium Hydroxide, 131. Caustic Soda, 207. Ferric Chloride, 119. Hydrogen Peroxide, 107. Iron Chloride, Ferric, 119. Lead Subacetate, 130. Potassium Acetate, 150. Carbonate, 161. Solution Potassium Hydroxide, 172. Sulphide, 181. Sodium Hydroxide I, 207. Hydroxide II, 207. Hydroxide III, 207. Sulphide, 220. Stannous Chloride, 226. Zinc Iodide-Starch, 234. Sorensen's Oxalate, 213. Specific Gravities. See Preliminary Note. Stannous Chloride, 225. Sulphurated Lime, 87. Sulphuric Acid, 34, 36, 37. Anhydride, 37. Sulphur Trioxide, 37. Synthetic Indigo, 110. Tables, 238, 239, 240, 241. of Atomic Weights, 238. of Equivalents, 238, 239, 240, 241. of Logarithms, 238, 239, 240, 241. Tannin, 42. Tertiary Calcium Phosphate, 86. Tetraiodofluorescein, 112. Thymol, 224. Tin, 224. Chloride, 225. Solution, 226. Tribasic Calcium Phosphate, 86. Tri calcium Phosphate, 86. Trinitrophenol, 31. Unweighable Residue. See Pre- liminary Note. Uranium Acetate, Free from So- dium, 227. Nitrate, 228. Uranyl Acetate, 227. Nitrate, 228. Vegetable Indigo, 111. 250 INDEX Water, Ammonia, 50, 51, 52. See Preliminary Note. 10 per cent, 52. 20 per cent, 51. 28 per cent, 50. Concentrated 51. Stronger, 50. Baryta, 71. Bromine, 77. Chlorine. 90. Distilled, 229. 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