LIST OF REAGENTS FOR ANALYTICAL PURPOSES \VITH NOTES INDICATING THE STANDARDS OF PURITY REGARDED AS NECESSARY FOR ANALYTICAL WORK This List has been brought to the notice of Manufacturers with the recommendation that the Labels on the Bottles containing Materials complying with these Tests should bear the Letters A. R.-signifying Analytical Reagent, PREFACE THISlist has been prepared for the purposeof indicating the reagents ordinarily required for analytical work and in order to ascertain how far they are obtainable in this country. The standards and tests are in the main those adopted by a Com-inittee appointed by the VIIIth International Congress of Applied Chemistry. Among the books referred to in con-nection with the preparation of the list, the use of Mr.Edmund White's book on '' Analytical Reagents,'' is specially acknowledged. Sp. gr.-The specific gravity is taken in each case at 15" compared with water at 15". B.P.-The boiling point is taken at. ordinary pressure. The figure in brackets, e.g. (z'), indicates the total range within which the reagents should boil-thus, 138" (2f') indicates a range of 137-139",the figure given being the middle value. REAGENTS FOR ANALYTICAL PURPOSES. ACETIC ACID.-Acid B.P. ACETIC ACID (GLACIAL).-Sp. gr. : 1.056; b.p.: I 1g0 (I") C. Solidifies when cooled and remains solid below r5*j0C. Contains 99.5 per cent. acetic acid. TESTS. Sulphuric Acid.-10 grams in IOO C.C. of water should not show turbidity after adding barium chloride, warming, and standing for two hours.Hydrochloric Acid.-I gram in 10C.C. of water should not show turbidity on addition of silver nitrate solution. Metals.-Io grams in zooC.C. of water should not show any precipitate or turbidity on addition of an equal volume of hydrogen sulphide solution, or on neutralisation with ammonia and addition of ammonium sulphide solution. Reducing Substances. -On adding 5 C.C. 2 perman-ganate solution to 5 grams of the acid diluted with 15 C.C. water, the pink colour should remain after standing fifteen minutes. ACETIC ANHYDRIDE.-Sp. gr. : 1.080;b.p. : 138O (2G). TESTS. Residue.-Io grams should not leave any weighable residue when evaporated in a glass dish on a sand-bath.Other Tests.-5 grams treated with gj C.C. of water, and tested as for acetic acid. * 6 ACETONE.-Sp. gr. : 0*797-0*798 ; b.p. : 57O (2"). Colourles arid miscible in all proportions with ether, alcohol, and water. Does not dissolve potassium hydroxide or anhydrous calcium chloride. TESTS. Residue.-20 C.C. should not leave any weighable residue when evaporated on a water-bath. Reaction.-Should be neutral to litmus. Action of Permanganate.-On the addition of one drop of potassium permanganate solution (I : 1,000) to 10c.c. of the acetone, the pink colour should not be completely discharged at the end of five minutes. Water.-Should be completely miscible without turbidity or separation into layers when mixed with an equal volume of light petroleuni (13.p.: 40-60'). ACETYL CHLORIDE.-B.p. : 51" (lo). TESTS. Phosphorus.--2 C.C. diluted with 10C.C. of water should give only a faint indication when tested with molybdic solution. AMMONIUM ACETATE. TESTS. Non-volatile Substances.-3 grams should not leave my weighable residue on ignition. Chloride.--I gram in 20 C.C. of water acidified with nitric acid should not show any opalescence on addition of silver nitrate solution. Sulphate.-1 gram in 20 C.C. of water acidified with hydro- chloric acid should not give any precipitate with barium chloride solution after standing for several hours. Heavy Metals and Iron.-s grams in IOO C.C. of water should not show any change with sulphuretted hydrogen 7 solution.Further, on addition of ammonium hydroxide and ammonium oxalate solution there should not be any colour or turbidity. AMMONIUM CARBONATE. TESTS. Volatile Matter.-5 grams should not leave any weighable residue on ignition in a platinum crucible. Sulphuric Acid.-5 grams in 200 C.C. of water, acidified with hydrochloric acid in slight excess, and heated to boiling, should not show any change on addition of barium chloride after one hour. Halogens.--:! grams in 50 C.C. of water, acidified with nitric acid, should not show any opalescence on addition of silver nitrate. Heavy Metals.--r gram in 20 C.C. of water, acidified with acetic acid, should not be changed by hydrogen sulphide solution. Thiocyanates.-1 gram in 20 C.C.of water acidified with hydrochloric acid should not give any red colour on the addition of one drop of ferric chloride snlution.AMMONIUM CHLORIDE. TESTS. Residue and Tarry Impurities.-s grams moistened with nitric acid and evaporated on a water-bath to dryness in a platinum crucible should leave a i.el?zite, not a yellow or reddish, saline residue. On heating thk with the flame it should volatilise, leaving less than 0.5 milligram residue, and the substance should remain colourless during volatilisation. Sulphate.-5 granis in 100 C.C. of water acidified with hydrochloric acid should not show turbidity after adding barium chloride solution and standing two hours. Metals.-Io grams in 100C.C. of water should not show any darkening on the addition of an equal volume of hydrogen sulphide solution.8 Iron.-5 grams in IOO C.C. of water should not show any immediate blue colour on the addition of one drop of potassium ferrocyanide solution. Thiocyanates.-5 grams in IOO C.C. of water acidified with hydrochloric acid should not produce a red colour on the addition of a few drops of ferric chloride solution. AMMONIUM FLUORIDE. TESTS. Residue.-5 grams ignited in a platinum dish should leave not more than 0.2 milligram residue. Chlorides.-5 grams in IOO C.C. of water should not show any opalescence on the addition of silver nitrate and nitric acid. Sulphate and Silicofluoride.-5 grams in 100 C.C. of water strongly acidified with hydrochloric acid should not give any turbidity on the addition of barium chloride solution.Metals.-5 grams in IOO C.C. of water should not produce a dark coloration or turbidity on the addition of ammonia and ammonium sulphide, or an equal volume of hydrogen sulphide solution. AMMONIUM MOLYBDATE. TESTS. Phosphoric Acid.-Io grams should give a clear solution with 25 C.C. of water and 15C.C. of ammonia of 0.91 sp. gr. This solution poured into 150 C.C. of nitric acid of 1-20 sp. gr. should not show any yellow precipitate after standing for two hours and slightly warming. Metals.-1 gram in 10C.C. of water rendered distinctly alkaline with ammonia should not show any darkening in colour after the addition of a few drops of ammonium sulphide solution. Sulphates and Chlorides.--Io grams in IOO C.C.of water acidified with nitric acid should not show any turbidity or opalescence after the addition of solution of barium chloride or of silver nitrate and standing several hours. 9 AMMONIUM NITRATE. TESTS. Residue and Tarry Impurities. -j grams heated cautiously with 5 drops of nitric acid in a platinum crucible should melt to a colourless fluid, and on continued heating to a low red heat should leave a residue weighing less than 0.5 milligram. Sulphates or Chlorides.-10 C.C. of a 10per cent. solu- tion slightly acidified with nitric acid should not show any turbidity or opalescence after addition of solution of barium chloride or of silver nitrate and standing several hours. Metals.-Io grams in IOO C.C.of water should not show any darkening in colour after addition of an equal volunie of hydrogen sulphide solution. Iron.-5 grams in IOO C.C. of water should not show any immediate blue colour on the addition of I drop of potassium ferrocyanide solution. Thiocyanates.-5 grams in IOO C.C. of water acidified with hydrochloric acid should not show any red colour on the addition of a few drops of ferric chloride solution. Nitrites-50 C.C. of a 2 per cent. solution acidified with I C.C. dilute sulphuric acid should not show any yellow-brown colour after adding I C.C. of a 0.5 per cent. freshly prepared solution of metaphenylenediamine hydrochloride and standing ten minutes. AMMONIUM OXALATE. TESTS. Solubility.-1 gram should form a bright solution in 25 C.C.of water. Residue.-3 grams heated to a low redness in a platinum dish should not leave any weighable residue. Sulphuric Acid.-5 grams in zoo C.C. of water heated to boiling, and acidified with hydrochloric acid should not show 10 any turbidity on addition of barium chloride solution and standing for several hours. Chlorides.-1 gram in 25 C.C. water, acidified with nitric acid, should not show any opalescence on addition of silver nitrate solution. Heavy Metals and Iron.-50 C.C.of a 2 per cent. solu-tion with I C.C. solution of ammonia and 2 C.C. ammonium sulphide solution should not show any darkening after standing one hour. AMMONIUM SULPHATE. TESTS. Solubility.-5 grams in 50 C.C. of water should give a bright solution neutral to methyl orange.Resid ue.-3 grams should not leave any weighable residue on ignition. Chlorides.--2 grams in 20 C.C. of water should not show any opalescence on addition of nitric acid and silver nitrate solution. Metals.--a grams in 20 C.C. of water should not be affected by hydrogen sulphide, or by ammonia and ammonium sulphide. Thiocyanates-1 gram in 10 C.C. of water, acidified with hydrochloric acid should not show any red colour on addition of ferric chloride. AMMONIUM SULPHIDE. TESTS. Volatile Matter.-Io C.C. should not leave any weighable residue on evaporating and heating in a porcelain capsule. Other Sulphur Compounds.-Io C.C. diluted with 50 C.C. of water should not give any precipitate on the addition of calcium chloride solution, even after standing (in a closed vessel) for several hours.11 AMMONIUM THIOCYANATE. TESTS. Solubility.-The salt should be entirely solubIe in 10parts of water or 10parts of absolute alcohol. Residue.--a grams should not leave any weighable residue on ignition. Sulphates.-Io grams in IOO C.C.of water should not show any turbidity 011 addition of barium chloride solution and standing twenty minutes. Metals.--xo grams in IOO C.C. of water should not show any darkening on adding a few drops of ammonium sulphide solution. Iron.-The presence of this impurity is usually indicated by a pinkish tint in the crystals. Even if these are colourless, a 10per cent. solution should not become pink.AMYL ALCOHOL.--Sp. gr. : 0.814 to 0.815; b.p. : 131' (-a"). TESTS. Residue.-Io C.C. should not leave any residue after evapo- ration in a glass dish over a water-bath. Furfuro1.-Not more than a pale yellow or reddish-brown tint should be produced by shaking with an equal volume of strong sulphuric acid. Miscibility.-~o C.C. should mix completely with 10C.C. of hydrochloric acid (sp. gr. : 1-17); the addition of 1.5 C.C.of water should produce a permanent turbidity. Oily Impurity.--2 C.C. with 10C.C. of water and 10C.C. of sulphuric acid should not show any oily layer after centrifug- ing in a graduated Gerber milk tube for several minutes. AMYL NITRITE.-At least 70 per cent. should boil between go-100'. ANILINE.-Sp.gr. : 1.027 ; should distil completely at 183"(2"). 12 ARSENIOUS ACID. TESTS. Solubility.--I gram should dissolve completely in 20 C.C. of 10per cent. ammonia solution. Residue.--;? grams should not leave a residue of more than 0-5 milligram on ignition. Sulphide of Arsenic.--Io grams dissolved in caustic soda solution should not show any brown coloration on addition of I or 2 drops of lead acptate solution. Antimony, Tin, or Cadmium.-o*5 gram in 50 C.C. of water with I C.C. hydrochloric acid should give a yellow pre- cipitate with hydrogen sulphide, which, after collection and once washing Tvitli distilled water, should be completely soluble in ammonium carbonate solution. BARIUM CARBONATE. TESTS. Su Iphates.--2 grams in 50 C.C.of water should be dissolved to a perfectly clear solution by a slight excess of hydrochloric.-acid.Chlorides.-1 grain in excess of dilute nitric acid should not show any opalescence with silver nitrate. Nitrates.-The colour of I gram in 10C.C. of acetic acid, tinted blue by indigo solution, should not be discharged on adding 10C.C.of strong sulphuric acid. Al kalies.-I grain dissolved in dilute hydrochloric acid, and the barium completely precipitated with sulphuric acid should give a filtrate which on evaporation and ignition should not leave any weighable residue. BARIUM CHLORIDE. TESTS. Sulphates.--2 grains should dissolve in 10C.C. of water, forming a bright solution, free from any opalescence. 13 Alkalies.-See Barium Carbonate. Nitrates.-See Barium Carbonate.Heavy Metals.-5 grams in IOO C.C. of water should not show any darkening in colour or a precipitate on the addition of hydrogen sulphide or aninioniuin sulphide solution. BARIUM HYDROXIDE. TESTS. Ot he\. Alkal ies.-See Barium Carbonate. Su I phates. --I gram in 30 C.C. of water should form a bright solution, free from opalescence, after addition of a slight excess of nitric acid. Chlorides.-The clear solution formed in testing for sulphates should not show any opalescence on addition of silver nitrate solution. Sulphides.-1 gram in 20 C.C. of water, with the addition of a distinct excess of hydrochloric acid, should not smell of hydrogen sulphide on warming, or be darkened by the addition of lead acetate solution.Lead and other MetalS.--I gram in 30 C.C. of water, with a slight excess of hydrochloric acid, should not show any darkening on addition of an equal volume of hydrogen su1phide solution. BARIUM NITRATE. TESTS. Sulphates.--I grani in 30 C.C. of water should form a per-fectly clear solution free from any trace of opalescence. Chlorides.-The clear solution formed in testing for sulphates should not show any opalescence after addition of nitric acid and silver nitrate solution. Alkalies and Heavy Metals. -See under Barium Chloride. ** 14 BENZENE.-B.p. : 80.5' (1'); map.:4-5". TESTS. Residue.-10 C.C. evaporated at a Ion-temperature from a glass dish should not leave any residue.Thiophen.-50 C.C. shaken with 20 C.C. of concentrated sulphuric acid should not be coloured brown ; a blue or green colour should not be produced on adding a crystal of isatin and further shaking. BROMINE. TESTS. Resid ue.-5 grams evaporated from a porcelain dish should leave less than 0.5 milligram of residue. lodine.--I C.C. shaken with 50 C.C. of water in a stoppered flask, and reduced iron or iron powder added in sinall portions until the liquid is almost colourless, after filtration. The filtered fluid should not assume a blue colour on the addition of 5 drops ferric chloride solution and starch paste. Organic Compounds.-If I C.C. be shaken in a stoppered flask with 50 C.C. of water, and ammonia solution added slowly until the brown colour disappears, oily drops should not separate, and the liquid should be clear and colourless, leaving a white residue of ammoniuni bromide when carefully evaporated to dryness.Sulphates--I gram of the ammonium bromide, formed in the foregoing test, in 20 C.C. of water, acidified with hydrochloric acid, should not give a precipitate with barium chloride, el-en after standing for several hours. CADMIUM SULPHATE. TEST. Arsenic.-Io grams should be distilled with arsenic-free hydrochloric acid (20 to 30 per cent. HC1) and 0.05 gram of pure ferrous chloride. The distillate measuring 20 C.C. when introduced into the Marsh-Berzelius flask should not show an arsenic mirror after 30 minutes. (See Appendix.) 15 CALCIUM CARBONATE.TESTS. Alkalies.-5 grams boiled with 50 C.C. water should yield a filtrate neutral to litmus ; 25 C.C. of this evaporated to dryness and gently ignited should leave a residue weighing less than I milligram. Chlorides.-I gram in dilute nitric acid should not show any opalescence with silver nitrate. Sulphates.--I gram dissolved in dilute hydrochloric acid should not produce any turbidity with barium chloride. Magnesia.-Dissolve 5 grams in dilute hydrochloric acid ; add ammonia until the liquid, after well shaking, smells strongly of ammonia, and then slight excess of ammonium oxalate solution. Warm and set aside two hours. Filter, and concentrate the filtrate. This should not show any turbidity after adding ammonia and sodium phosphate solution and standing several hours.Metals.-5 grams in IOO C.C. of water with slight excess of hydrochloric acid should not show any colour or turbidity (0) on adding an equal volume of freshly prepared hydrogen sulphide solution, (b) on adding a slight excess of ammonia and a few drops of animonium sulphide solution. Phosphate.-Io grams in jo C.C. of nitric acid should llot show any reaction on adding molybdic solution. CALCIUM CHLORIDE. TESTS. Solution in Water.-Should be perfectly clear and neutral . Barium and Strontium.--I gram in 10 C.C. of water should not show any turbidity after adding 20 C.C. of calcium sulphate solution and standing several hours. Iron and Heavy Metals.-1 gram in 20 C.C. of water and j drops of amnionia solution should not shew any darkening or discoloration on the addition of 5 drops of ammonium sulphide solution. Phosphate.-See Calcium Carbonate.Alkal ies.-5 grams dissolved in water, rendered aiiimoniacal, precipitated with ammonium osalate and filtered should yieid a filtrate which on evaporation and ignition should not leave a weighable residue. Nitrate.-o.I gram dissolved in strong sulphuric acid should not give a blue colour on adding diphenylaniine reagent. (See Appendix.) CARBON DISULPH1DE.-B.p.: 46*5O(1");50 c.c.should not leave an appreciable residue on evaporation. There should not be aluminous flame when the liquid is ignited on a glass rod. CHLOROFORM.-B.p.: 61" (2'); sp. gr.: 1*.+85-1*+90. TESTS.Residue.--To C.C. on evaporation should not leave any iveig h abl e r es id ue . Free Acid and Chlorine.-Agitate 5 C.C. with 10C.C. of water. Allow the undissolved chloroform to subside and decant the upper aqueous layer. This should not redden blue litmus paper or show any opalescence on the addition of silver nitrate soiutioIl ; if to another portion a few drops of solution of cadmium iodide and then starch paste be added, a blue colour should not appear. CHROMIC ACID. TESTS. Su1phate.-I gram in 50 C.C. of water should yield a clear sclution, which should not show any turbidity after adding I C.C. hydrochloric acid and 5 C.C. barium chloride solution. Potassium Salt.-Carefully heat I gram to low redness in a porcelain crucible. Triturate the residual chromic oxide with 20 C.C.of water, filter and evaporate the filtrate to dry- ness, and dry at 120--150'.The residue should not weigh more than 0.01gram. 17 CITRIC ACID. TESTS. Ash.-5 grams carefully ignited should not leave any weigh- able residue. Oxalic and Tartaric Acids.--I gram in 5 C.C. of a 33 per cent. clear solution of potassium acetate should not give any turbidity after standing thirty minutes, even after the addition of an equal volume of go per cent. alcohol. Sulphuric Acid.--I gram in 10 C.C. of water should not give any immediate turbidity with barium chloride solution. Lead.-j grams in 10 C.C. of water, nearly neutralised with ammonia, should not show any darkening on the addition of 40 C.C. hydrogen sulphide solution, and standing for thirty minutes.Iron.-The colourless and faintly acid liquid obtained in testing for lead should show only the faintest darkening on adding sufficient ammonia solution to give the liquid a dis-tinctly alkaline reaction. COPPER SULPHATE. TESTS. Solubility.--.l grams in 20 C.C. of water should form a perfectly clear solution, which should not show any deposit on standing for several hours. Iron.--j grams dissolved in water and boiled with I C.C. of nitric acid should not give any precipitate with excess of ammonia. Other Impurities.-+ grams are dissolved in IOO C.C. of water, z C.C. of hydrochloric acid added, and the copper completely precipitated with hydrogen sulphide.The liquid should eventually be heated to boiling while the gas is passing through it. The filtrate, after evaporation, should not leave a residue weighing more than z milligrams xftx ignition. ETHER.-Sp. gr. : 0.720; b.p. : 35" (2"). TESTS. Residue.---20 C.C. on evaporation should not leave a residue. Free Acid.-Shaken with an equal volume of water the latter should be neutral to litmus. Water.-Should form a clear liquid when added to an equal volume of carbon disulphide. Aldehyde.-3o C.C. with 5 grams of solid potash after twenty-four hours in the dark should not show any brown colour. ETHYL ALCOHOL-PURE.-gg.5 per cent. alcohol. FERRIC CHLORIDE. TESTS. Solubility.-Should form a clear solution in its own weight of distilled water. Zinc, Copper, and Alkalies.-Dissolve 5 grams in IOO C.C.of water, completely precipitate with ammonia solu- tion, boil and filter. The filtrate should be colourless, and one half evaporated to dryness and ignited should leave a residue not exceeding I milligram. The filtrate should not give any precipitate with ammonium sulphide solution. Nitrates-Dissolve I gram in 10C.C. of water, conipletely precipitate by the addition of ammonia, and filter. Neutralise the fiitrate, add a crystal of ferrous sulphate, and carefully pour suipnuric acid down the side of the tube : a brown zone should nrx appear at the junction of the two fluids. Ferrous Salts.--:! grams in IOO C.C. of water should not show any blue colour on the addition of a few drops of freshly prepared potassium ferricyanide solution.Sulphate.-5 grams are dissolved in 50 C.C. of water preci- pitated with ammonia and filtered ; the filtrate should not give 19 a precipitate with barium chloride after acidification with acetic acid. Arsenic.-Io grams distilled with hydrochloric acid should give a distillate which on dilution and saturation with sulphuretted hydrogen does not give a precipitate of arsenious sulphide even on standing (in a closed vessel) for twenty-four hours. (See also Appendix.) FERROUS AMMONIUM SULPHATE. -Should not contain less than 99-9 per cent. FeSO, (NH,), SO,, 6H,O. FERROUS SULPHATE. TESTS. Solu bility.-Z grams should dissolve to a clear solution in 10C.C.freshly boiled water. Copper, Zinc, and Alkalies,-Dissolve 5 grams in 50 C.C. of n-ater ; osidise with nitric acid and boil ; completely precipi- t?te the iron by a slight addition of ammonia and filter, and test the filtrate as under Ferric Chloride. HYDRIODIC ACID.-Sp. gr. : 1-7. TESTS. Residue.-z C.C. evaporated in a capsule and the dish gently heated should not leave more than 0.5 milligram residue. Sulphates.-1 C.C. diluted with water to 20 C.C. should not show any turbidity on adding barium chloride solution. Titration.-Using phenolphthalein as indicator, the acid should show not less than 52 per cent. HI. HYDROCHLORIC ACID. TESTS. Resid ue.-5o C.C. evaporated in a platinuiii dish should not leave a residue weighing iiiore than I milligram.Sulphates.-50 C.C. are evaporated to 5 C.C. and then diluted with water to IOO C.C. On adding 5 C.C. barium chloride solution and standing twelve hours there should not be a precipitate. Arsenic.--a~ C.C.of the acid treated in the hlarsh-Berzelius apparatus using sensitive zinc (see Appendix) for thirty minutes should indicate less than I part per million of arsenic. Metals.-Dilute 10C.C. to 50 C.C. with water, and add an equal volume of hydrogen sulphide solution. Darkening should not occur after standing one hour. Iron.-Dilute 5 C.C. to 20 C.C. with water, and add I C.C. potassium thiocyanate solution. A pink coloration should not appear. Free Chlorine.-Dilute 2 C.C. to 20 C.C. with ivater; add zinc iodide or cadmium iodide and starch paste.11 blue colora- tion should not appear. HYDROFLUORIC ACID. TESTS. Residue.-Io C.C. evaporated in a platinum basin should not yield a residue weighing more than 0.5 milligram after ignition at a low red heat. Sulphate.-I C.C. evaporated to complete drypess in a platinum dish over the water bath, and the dish rinsed u-ith 10 C.C. of water, should yield a liquid ~vhichdoes not gi\-e any immediate turbidity on the addition of two drops of hydrochloric acid and I C.C. of barium chloride solution. (It is necessary to remove the hydrofluoric acid by evaporation, owing to the insolubility of barium fluoride.) Silica.-Dilute 2 C.C. with 10 C.C. of water, and add a solution of I gram of potassium chloride in 5 C.C.of water. Turbidity or precipitate of potassium silicofluoride should not be produced. Metals,--Dilute 5 C.C. with 40 C.C. of water, and add 50 C.C. hydrogen sulphide solution. There should not be any turbidity or darkening. 21 Iron.-The foregoing liquid should not give a coloration with ammonia. IODIC ACID. TEST. Solubility.-The acid should dissolve in an equal weight of water, giving a clear solution. Residue.--2 grams on ignition should not leave any weighable residue. IODINE. TESTS. Residue.-1 gram gently heated in a porcelaic dish should not leave any visible residue. Titration with sodium thio- sulphate should indicate not less than 99.9per cent. iodine. LEAD ACETATE. TESTS. Solubility.-5 grams should dissolve in jo C.C.freshly boiled and cooled distilled water with only the faintest opalescence. Copper and iron.-2 grams in 10C.C. of water, treated with potassiuni ferrocyanide solution should gix-e a pure white precipitate free from any tinge of blue or bron-n. Chloride.-1 gram in 20 C.C.of distilled water with two drops of acetic acid should not give any immediate precipitate with sill-er nitrate solution. Alkalies and Alkaline Earths.-Dissolve 2 grams in 40 C.C. of water ; add hydrochloric acid drop by drop until no further precipitate is produced, remoxre the remainder of the lead from the solution by hydrogen sulphide and filter. The filtrate evaporated to dryness and ignited should yield a residue weighing not more than I milligram.Nitrate.-The colour of I gram in 10C.C.of acetic acid, tinted blue by indigo solution, should not be discharged on adding 10C.C. of strong sulphuric acid. 22 MAGNESIUM CHLORIDE. TESTS. Solubility.-Soluble in less than its own weight of water and about six times its weight of go per cent. alcohol. Sulphates.-1 gram in 20 C.C. of water, acidified with hydrochloric acid should not give any precipitate with barium chloride even after standing for one hour. Phosphoric Acid and Arsenic Acid.-Dissolve 5 grains in 20 C.C. of water, add ainmoniuin chloride and ammonia in excess, and allow the solution to stand for some time. There should not be any precipitate or turbidity. (See also Appendix.) Iron and Heavy Metals, and Calcium.-Dissolve I gram in 20 C.C.of water, and add 5 drops of ammonium sulphide solution ; darkening should not appear. On adding a small quantity of ammonium oxalate there should not be a turbidity after standing for two hours. MAGNESIUM O'XIDE. TESTS. Su Iphuric Acid.-5 grams dissolved in a little hydrochloric acid, the solution diluted to about IOO c.c., heated to boiling,' and barium chloride added, should not show any precipitate after standing for several hours. Arsenic.-Distil jgrams with about 50 C.C. of arsenic free hydrochloric acid (20 to 30 per cent. HCI) and 0.05 gram of ferrous chloride. The distillate, measuring about 25 C.C. when introduced into the Marsh-Eerzelius apparatus, should not show any arsenical mirror at the end of 30 minutes.(See Appendix.) MANGANESE SULPHATE. TESTS. Solubility.-Soluble in about its own weight of water to a clear solution. Chlorides-1 gram in 40 C.C. of water with I C.C. nitric 23 acid should not give more than the faintest opalescence on the addition of silver nitrate solution. Iron.-Dissolve I gram in jo C.C. of water, add 5 drops hydrochloric acid and I C.C. chlorine water. Boil, cool and add 2 C.C. potassium thiocyanate solution ; a red colour should not be produced. Magnesium and Alkalies.-Dissolve 2 grams in 50 C.C. of water, add 3 grams of ammonium carbonate dissolved in 20 C.C. of water; warm the mixture, set aside to cool and then filter. Evaporate the filtrate to dryness and ignite the residue, which should weigh not more than I milligram.Calcium.--I gram in 50 C.C. of water with the addition of 2 C.C. ammonium oxalate solution should not give any pre- cipitate within one minute. Zinc.-1 grain in 20 C.C. of ivater with 5 drops acetic acid should not give any precipitate on the addition of an equal lrolume of hydrogen sulphide solution. MERCURIC CHLORIDE. TESTS. Solubility and Mercurous Chloride.-Soluble in about 20 parts of cold water. Tn-o grams with 20 C.C. of ether should form a clear solution, and should not leave any insoluble residue. Fixed Residue.-Dissolve 2 grams in jo C.C. of water and remove the mercury by hydrogen sulphide. lhe filtrate when evaporated and ignited should not leave any weighable residue.Arsenic.-On digesting the precipitate from the zboi-e with dilute ammonia, filtering and acidifying with hydrochloric acid, there should not be any yellow coloration or precipitate. (See also Appendix.) METHYL ALCOHOL.-Sp. gr.: 0.796 J b.p. 65" (1'). TESTS. Resid ue.-Should not leave any residue on evaporation. 24 Acetone.-5 C.C. of the alcohol diluted with 40 C.C. of water should not show any yellow colour, turbidity, or odour of iodoform on addition of caustic soda solution and a few drops of iodine solution. Colour Test.-The addition of a large excess of strong caustic soda solution should not produce any coloration, and the gradual addition of an equal volume of strong sulphuric acid should nGt produce more than the faintest yellow colour.MOLYBDIC ACID. TESTS. Dissolt-e in ammonia, and apply tests as under Ammonium Moly bdate. NITRIC ACID.-Sp. gr. : 1-42. TESTS. Residue.-Io C.C. evaporated to dryness in a platinum dish on the water-bath and then heated to IZOO should not leave any weighable residue. Su I phates.-5o C.C. evaporated to 5 C.C. on a water-bath, the residue, diluted with water to 50 C.C. and barium chloride solution added, should remain perfectly clear after standing twelve hours. Chlorides.-5 C.C. diluted with water to 50 C.C. and silver nitrate solution added should not show any opalescence. Metals.-zo C.C. of the acid diluted with water, ammonia added in excess and subsequently ammonium sulphide and ammonium oxalate, should not show any dark colour or turbidity .OXALIC ACID.-Should not contain less than 99.8 per cent, H2C201,aH,O. TESTS See Ammonium Oxalate. 25 PERCHLORIC ACID.-Sp. gr. : 1-12. TESTS. Residue.-5 C.C. evaporated and gently ignited should not yield a weighable residue. Chlorides.-1 C.C. diluted with 20 C.C. of water and I C.C. nitric acid should give only the faintest opalescence on the addition of silver nitrate solution. Sulphates.-1 C.C. diluted with 20 C.C.of water, acidified with hydrochloric acid, should not give any immediate turbidity on the addition of barium chloride solution. Metals.--2 C.C. diluted with 20 C.C. of water, made faintly alkaline with ammonia, and ammonium sulphide added, should remain colourless.Barium.--2 C.C. diluted with 20 C.C. of water and dilute sulphuric acid added should not give any immediate turbidity. PHOSPHORIC ACID.-Sp. gr. : 1-75, TESTS. Calcium and Other Metals.-1 C.C. diluted with 20 C.C. of water and rendered distinctly alkaline by ammonia, should not give any turbidity on the addition of ammonium osalate solution, and should remain colourless with ammonium sulphide. Chlorides.-1 C.C. diluted with 10 C.C.of water should not show any opalescence with silver nitrate solution. Phosphites.-1 C.C. diluted with 10 C.C. of water, mercuric chloride solution added and the whole gently warmed, should not show any turbidity. Nitrates.--a grams of brucine are placed in a test tube and moistened with two drops of water and -a C.C.pure concentrated sulphuric acid are added. The phosphoric acid is carefully poured over the mixture, which is allowed to stand for a few minutes. red ring should not be formed at the junction of the two liquids. Metaphosphoric Acid.-The dilute acid, when added drop by drop to a dilute solution of albumen, should not pro- duce any turbidity. Sulphuric Acid.-IVhen diluted with ten times its volume of water, it should not gi1.e any reaction with barium chloride solution. Arsenic.--2 C.C. diluted with 20 C.C. of water and introduced in the Marsh-Berzelius apparatus should not show any arsenical mirror after thirty minutes. (See Appendix.) POTASSIUM DICHROMATE. TESTS. Chlorides.--a grams in IOO C.C. of water with j C.C.nitric acid and warmed to jo" should not show any opalescence with silver nitrate solution. Sulphates.-2 grams with IOO C.C. of water and 5 C.C.of hydrochloric acid should not show any precipitate after the addition of barium chloride solution and standing two hours. Alkaline Earths.--2 grains in 40 C.C. of water and rendered distinctly alkaline with ammonia should not give any turbidity on adding I C.C. ammonium oxalate solution and standing several hours. Sodium.-Must not contain more than traces of sodium. POTASSIUM B1SULPHATE.-(Fused). TESTS. Sol ubiI ity.-Forms a clear solution with twice its weight of water. Chlorides.-1 gram in 20 C.C. of water should not show any opalescence on the addition of silver nitrate solution.Heavy Metals and lron.---I gram in 20 C.C. of water should not show any darkening on the addition of an equal volume of hydrogen sulphide solution followed by ammonia. Ammonia.--Io grams distilled with a little pure caustic soda solution should yield a distillate requiring not more than 0.1C.C. of acid for its neutralization. 27 At*senic.-z grams dissolved in 10C.C. of water and intro- duced into the Marsh-Berzelius apparatus should not show any arsenical mirror after thirty minutes’ action. (See Appendix.) POTASSIUM BROMIDE. TESTS. Free Alkali.-5 grams in IOO C.C. of water should not affect neutral litmus paper. Heavy Metals and Iron.-1 gram in 20 C.C. of water should not show any darkening on the addition of an equal volume of hydrogen sulphide solution, even after the addition of ammonia. Sulphates--I gram in 20 C.C.of water should not show any turbidity after adding barium chloride solution and standing for two hours. Thiocyanates.-1 gram in 20 C.C. of water should give a j*eZlou,,and not a red or reddish-brown, coloration on the addi- tion of two drops of ferric chloride solution. Chloride.-1 gram of the pure salt freshly powdered and dried, titrated with solution of silver nitrate will require, if pure, 83-95 C.C.; it should not require more than 84-5, corresponding to about I per cent. potassium chloride. lodine.-I gram is dissolved in 20 C.C. of water. Ferric chloride solution and a few C.C. of chloroform are added. The latter should not be coloured violet on shaking.6romate.--I gram in 10C.C.of water should not show any colour on addition of dilute sulphuric acid, and on shaking with chloroform this should not become yellow. POTASSIUM CARBONATE.-Should not contain less than gg per cent. K,CO,. TESTS. Solubility.-Tliith 5 parts of water it should form a clear solution. 28 Chlorides.-1 gram in 20 C.C. of water, acidified with nitric acid, should give only the faintest opalescence with silver nitrate solution. Sulphates.--j grains in 100 C.C.of water, acidified with hydrochloric acid, should remain clear on addition of barium chloride solution even after two hours. Heavy Metals and Iron.--I gram in 20 C.C. of water should not give any darkening on the addition of an equal volume of hydrogen sulphide solution.Nitrate.-Dissolve 0.5 gram in z C.C. of water, add dilute sulphuric acid until the liquid has a faintly acid reaction, and dissolve in it a crystal of ferrous sulphate. Pour down the side of the tube sufficient strong sulphuric acid to form a distinct layer. A brown zone should not appear at the junction of the two liquids. Arsenic.-3 grams dissolved in 10 C.C. of water acidified with hydrochloric acid purified from arsenic and introduced into a Marsh-Berzelius apparatus should not show any arsenical mirror after 30 minutes’ action. (See Appendix.) POTASSIUM CHLORATE. TESTS. Solubility.-1 gram gently warmed with 16 C.C. of water forms a clear neutral solution. Alkaline Earths.--1 gram dissolved in 20 C.C.of water should not slio~vany turbidity on the addition of ammonium oxalate solution even after standing several hours. Chlorides-1 gram in 20 C.C. of water should cot show any opalescence on the addition of silver nitrate solution. Sulphates.-1 gram in 20 C.C. of water should not show any turbidity on the addition of barium chloride solution even after standing two hours. Heavy Metals.-j grams in 50 C.C. of warm water should not show any darkening on the addition of an equal volume of 11yd rog e n su1ph id e solution . 29 POTASSIUM CHLORIDE. TESTS. Solubility.-Forms a clear neutral solution in 4 parts of mate r . Sulphates.-s granis in IOO C.C. of water shoulcl not give a turbidity with barium chloride solution.Alkaline Earths.-1 gram in 20 C.C. of water should not show any turbidity on the addition of ammonium osalate solution even after standing several hours. Iron.-I gram in 20 C.C. of water with I C.C. each of nitric acid and potassium thiocyanate solution should not show any red colour even after gently warming. Heavy Metals.---Dissolve 3, grains in 50 C.C. of water and add an equal volume of hydrogen sulphide. There should not be any darkening. POTASSIUM CHROMATE. TESTS. Solubility.-Forms a clear solution with 3 parts of water, which should show only a faint alkalinity to litmus. Other Tests.-See Potassium Bichromate. POTASSIUM CYANIDE. TESTS. Solu bi Iity.-Forms with 3 parts of water a clear colourless solution having an alkaline reaction. It should contain not less than 96 per cent.KCS. It should dissolve completely in hot (60 per cent.) alcohol ; an insoluble residue, effervescing with acids, shows the presence of carbonate. Sulphate.--I gram. in 20 C.C. of water and acidified with about j C.C.of hydrochloric acid should not give any precipitate with barium chloride solution. Thiocyanate and Ferrocyanide.-1 gram. in 20 C.C. of water acidified with 5 C.C. of hydrochloric acid should not give either a red or a blue coloration on the addition of a drop of ferric chloride solution. Chloride.-1 gram should be ignited in a porcelain crucible with 2 grams of potassium nitrate and 10 grams of potassium carbonate. The residue dissolved in water and acidified with nitric acid should not give more than a faint opalescence with silver nitrate solution. Sulphide.-1 gram in 20 C.C.of water should give a pure white precipitate with lead acetate solution. POTASSIUM FERRICYANIDE. TESTS. Solubility.-1 gram dissolves completely to a clear red solution in 3 C.C.of water, Ferrocyanide.-Take a crystal weighing about 0.25 gram, shake it rapidly with 20 C.C.of water to wash the siirface; reject the washings and dissolve the remainder of the crystal in 50 C.C.of water ; on adding I drop of ferric chloride solution a blue colour should not appear. SuIphate.--r gram in 30 C.C. of water and IC.C. hydro- chloric should not give any turbidity on the addition of barium chloride solution.POTASSIUM FERROCYANIDE. TESTS. Solubility.--1 gram dissolves in 5 C.C. of water to a clear pale yello~v neutral solution. SuIphate.--1 gram in 20 C.C. of water and IC.C. hydro-chloric acid should not gi\,e any turbidity on adding barium chloride solution even after standing for two hours. POTASSIUM HYDROXIDE, TESTS. Solu bility.-5 grams should dissol1.e to a clear colourless solution in 10C.C. of water. 31 Silica.-The solution of j grams in water with excess of hydrochloric acid is evaporated to dryness. The residue is heated for thirty minutes and then dissolved in 20 C.C. of water with the addition of zC.C. of hydrochloricacid. The resulting solution should be clear and free from any flocculent, insoluble matter.Alumina.-5 grams in 20 C.C. of water acidified with acetic acid and warmed for thirty minutes should not show a preci-pitate or turbidity. Other Tests.-See Potassium Carbonate. POTASSIUM IODIDE. TESTS. Solubility.-Forms a perfectly clear solution with its own weight of water. Free Alkali.--I gram in 20 C.C. of freshly boiled and cooled water should not show any red colour on the addition of one drop of phenolphthalein solution. Iodate.-1 gram in 20 C.C. of water with 2 C.C. each of starch paste and tartaric acid solution should not imme-diately become blue. Sulphate.-1 gram in 20 C.C. of water with 2 C.C. dilute hydrochloric acid should not show a turbidity after the addition of I C.C. barium chloride solution and standing one hour.Metals.--I gram in 20 C.C. water should not show any darkening on the addition of an equal volume of hydrogen sulphide solution and some ammonia. Chlorides and Bromides.-Dissolve 0.5 gram in 6 C.C. dilute ammonia solution, add 13 C.C. silver nitrate solution, shake thoroughly, and filter. To the filtrate add sufficient nitric acid to give a distinct acid reaction : only the faintest opalescence should appear. 32 POTASSIUM NITRATE. TESTS. Solubility.--2 grams in 10C.C. of water should form a clear solution, having a neutral react ion. Sulphate.--2 grams in 40 C.C. of water, with I C.C. of hydrochloric acid should not show a turbidity on the addition of barium chloride solution and standing several hours. Chloride.--:! grams in to C.C.of water and I C.C.nitric acid should not show any opalescence on adding silver nitrate solution. Metals.--2 grams in 40 C.C.of water should not show any darkening on the addition of ail equal volume of hydrogen sulphide solution. Iron.--2 grams in 40 C.C. of water with 5 C.C. nitric acid should not show any red colour on the addition of I C.C. potassium thiocyanate solution. Nitrite.--a grams in 40 C.C.of water with I C.C. dilute sulphuric acid (1.1I) and I C.C. of freshly prepared colourless solution of metaphenylenediamine hydrochloride (I in ~oo), should not give a yellow or yellowish brown coloration. POTASSIUM OXALATE (NEUTRAL). TESTS. See ,Ammonium Oxalate. POTASSIUM PERMANGANATE.-Should contain not less than 99-9per cent.KMnO,. TESTS. Chloride, Sulphate and Nitrate.-Dissolve I gram in 50 C.C. of water, add 10 C.C. of alcohol, heat nearly to boiling until the permanganate is entirely reduced and the super-natant liquor has become colourless. Filter, and to 10C.C. of the filtrate add 0.5 C.C. nitric acid and silver nitrate solution ; to another 10 C.C. add I C.C. hydrochloric acid 33 and barium chloride solution ; turbidity should not imme- diately appear in either case, and only the faintest opalescence even on standing thirty minutes. To another 5 C.C. of the filtrate add I drop of diphenylamine solution (seeAppendix), and then pour I C.C. sulphuric acid down the side of the tube; a blue colour should not appear at the line of contact of the two fluids.POTASSIUM THIOCYANATE. TESTS. Solubility.-Easily soluble in water, forming a clear, colourless solution. Should also be completely soluble in 10parts of alcohol. Sulphates.-1 gram in 20 C.C. water and 3 drops hydro- chloric acid should not show any turbidity on the addition of barium chloride solution. Heavy Metals.-I gram in 20 C.C. of water should not show any darkening on the addition of an equal volume of hydrogen sulphide solution. Iron.-The solution (I : 20) should not show any colour on addition of a few drops of dilute hydrochloric acid. SILVER NITRATE. TESTS. Solu bility.-Soluble in less than its own weight of water and in about 20 parts of alcohol. Copper, Bismuth, Lead Salts-1 gram in 5 C.C.water treated with 10C.C. ammonia solution should remain clear and c olou rless. SODIUM ACETATE. TESTS. Chlorides, Sulphates, Heavy Metals and Iron.-See Ammonium Acetate. 34 SODIUM BICARBONATE. Chlorides, Sulphates, Heavy Metals and Iron, Nitrates.-As for Potassium Carbonate. Carbonate.-A solution of I gram in 20 C.C. of water (obtained without agitating the liquid, and at a temperature not exceeding 15") should not at once assume a red colour on the addition of 3 drops of phenolphthalein solution ; should a slight reddish colour be visible, it should disappear on adding 0.2 C.C. normal hydrochloric acid. Ammonia.-On heating in a test tube, no smell of ammonia should be detected, and moist turmeric paper should not be coloured brown by the vapours evolved.SODIUM BISULPHATE. TESTS. See Potassium Bisulphate. SODIUM BORATE (BORAX). TESTS. Metals, Earths.-1 gram dissolved in 30 C.C. of hot water acidified with hydrochloric acid, should not give any reaction with hydrogen sulphide solution. A precipitate should not form on adding excess of sodium carbonate to the same solution. Carbonates, Sulphates and Chlorides.-1 gram in 30 C.C.of water acidified with nitric acid should not evolve carbonic acid, and the addition of barium chloride solution or silver nitrate solution should not produce any change. SODIUM CARBONATE (.\nhydrous).-Must not contain less than 99.5 Na,CO,. TESTS. Chloride, Sulphate, Heavy Metals, Iron, Arsenic.- See Sodium Bicarbonate. 35 SODIUM CHLORIDE.TESTS. See Potassium Chloride. SODIUM HYDROXIDE.-(Purified by Alcoholj. TESTS. See Potassium Hydroxide. SODIUM NITRITE. TESTS. Sulphate.-1 gram in 20 C.C.of water and I C.C. nitric acid should not give any turbidity on the addition of barium chloride solution. Chlorides.-1 gram in 20 C.C. of water with I C.C. nitric acid should not show any opalescence on the addition of silver nitrate solution. Metals.-1 gram in 20 C.C. of water should not show any .darkening on the addition of an equal volume of hydrogen sulphide solution or I drop ammonium sulphide solution. Quantitative Determination.-Titration with per-manganate solution should not indicate less than 98 per cent. sodium nitrite.SODIUM PEROXIDE. TESTS. Sulphate.--:I solution of 10 grams in excess of hydrochloric acid with IOO C.C. of water should remain clear after the addition of barium chloride solution. Chloride.-3 grams added in small quantities to a mixture of 20 C.C. nitric acid and 10 C.C. of water should not show more than a faint opalescence with silver nitrate solution. Heavy Metals.--See Potassiqm Carbmate. 36 SODIUM PHOSPHATE. TESTS. Chlorides.--1 gram in 20 C.C. of water with I c.c nitric acid should not show more than the faintest opalescence, on the addition of silver nitrate solution. Sulphates.--a grams in 20 C.C. of water with I C.C. hydro-chloric acid should not give a turbidity on the addition of barium chloride solution and standing for two hours. Metals.--I gram in 20 C.C.of water should not show any darkening on the addition of an equal volume of hydrogen sulphide solution or I drop of ammonium sulphide solution. SODIUM SULPHIDE. TESTS. Solubility.--j granis should dissolve in 10C.C.of water, forming a clear solution. Other Sulphur Compounds.--I gram in 10 C.C.of water treated with z C.C. hydrochloric acid should evolve hydrogen sulphide and give only a faintly opalescent solution. SODIUM THIOSULPHATE. TESTS. Solubility.-1 gram in 20 C.C. of water should give a white precipitate free from any brown tint on the addition of a few drops of silver nitrate solution. Calcium.--I gram in 20 C.C. of water should not give any immediate turbidity on the addition of ammonium oxalate solution.Sulphate and Sulphite.-Dissolve 3 grams in 50 C.C. of water, and add decinormal iodine solution until the thiosulphate is entirely converted into tetrathionate and excess of iodine remains : this solution should not give any turbidity on the addition of barium chloride solution, I gram in 10C.C. of water should be clear, and should not show more than a faint pink tinge with phenolphthalih solution. 37 STANNOUS CHLORIDE. TESTS. Foreign Metals,-Dissolve 2 grams in a mixture of 50 C.C. water and 6 C.C. hydrochloric acid; dilute the solution to IOO c.c., and conzpletely precipitate the tin with hydrogen sulphide. The filtrate evaporated to dryness and ignited should not leave any residue, or one weighing less than I milligram. Sulphate.-Dissolve I gram in a mixture of 10C.C.of water and 3 C.C. hydrochloric acid; dilute to 50 C.C. with distilled water, and add barium chloride solution; an imme- diate turbidity should not be produced. Arsen ic.-3 gratns should be distilled with arsenic-free hydrochloric acid containing al,out 30 per cent. I-ICl. The distillate measuring 20 C.C. when introduced into the Marsh- Berzelius flask should not show any arsenic mirror after 30 minutes. (See Appendix.) SULPHURIC ACID. TESTS. Residue.-10 grams should not leave any weighable residue on evaporation and ignition in a platinum capsule. Lead.-On mixing the acid with five times its volume of strong alcohol a turbidity should not appear, even after long standing.Other Metals.--Io C.C. of the acid diluted with water, ammonia added in excess, and a few drops of ammonium sulphide and ammonium oxalate should not show a green colour or turbidity; 20 C.C. diluted with IOO C.C. of water should neither turn brown nor give a precipitate after passing hydrogen sulphide and standing for some time. Halogens.--a grams in 30 C.C.of water should not show any opalescence on adding silver nitrate solution. Selenium.-To 2 C.C. of the sample 2 C.C.of hydrochloric acid, containing a little sodium sulphite, should be carefully 38 added so as to form a layer ; neither a red zone nor a reddish precipitate should appear on heating. Reducing Substances.-15 C.C. of the acid should be diluted with 60 C.C.of water, the solution cooled, and I drop of N I. permanganate added ; the solution should remain distinctly coloured for a few minutes. Ammonia and other Nitrogen Compounds.-20 C.C. after heating in a Kjeldahl flask with I gram of cane sugar and 10 grams of potassium bisulphate till colourless should on distillation with pure sodium hydroxide give a distillate having an alkalinity equal to not more than 0.3 C.C. 2 NaOH. Arsen ic.-5 grams partly neutralised with pure sodium carbonate and diluted to 20 C.C. when introduced into the Marsh-Berzelius apparatus, should not give an arsenic mirror at the end of 30 minutes. (See Appendix.) URANIUM ACETATE. TESTS. Solubility.-1 gram dissolved in 25 C.C.of water forms a clear solution, or one having a faint opalescence which is removed on the addition of a few drops of acetic acid. Sulphates.-o*j gram dissolved in 20 C.C. of water should not give any turbidity on the addition of barium chloride solution. Alkalies.-Dissolve I gram in 25 C.C. of water, heat to boiling and precipitate by the addition of excess of ammonia solution. The filtrate on evaporation and ignition should yield a residue weighing not more than 4 milligrams. Calcium.-I gram in 25 C.C. of water should give a clear solution on the addition of excess of ammonium carbonate solution. Metals.-The liquid from the preceding test should not show any darkening on the addition of 3 drops of ammonium sulphide solution previously diluted with 5 C.C.of water. 39 URANIUM NITRATE. TESTS. Solubility.--r gram with 20 C.C. of water forms a clear solution having an acid reaction. Other Tests. See Uranium Acetate. ZINC. (Arsenic free.) APPENDIX Diphenylarnine Reagent.---The reagent is prepared by dissolving 0.085 gram of diphenylamine in 190C.C.of dilute sulphuric acid (I : 3), and, when cold, making up to 500 C.C. with strong sulphuric acid. Test for Traces of Arsenic.-This is carried out sub-stantially as described in the report of the Joint Conimittee of the Society of Cheniical Industry and of the Society of Public Analysts (1..SOL Chenz.Id, 1902, 21, 93; ,41idyst, 1902, 27, 45). Zinc sold as “ arsenic-free ” is liable to be insensitive or may contain traces of arsenic, and before a quantity is pur-chased samples should be obtained and rigorously tested.The sensitiveness of zinc is invariably increased by the use of cadmium sulphate, and the use of this salt must now be regarded as an essential and inseparable feature of the Marsh- Berzelius process when delicate and accurate results are required, as for instance for testing the purity of reagents (uide Analyst, 1907, 3.3, 247, and 1906, 31, 3). BRADBUIZY, AGSEW, & CO. I.D., I’JZlX’I‘EliS, LONDON ANI) TONIIR1I)GE. (59e9-j-15)