INDUSTRIAL AND ENGINEERING CHEMISTRY
1372
and allow to stand 3 hours protected against loss or access of ammonia. Decant 25 cc. of the clear liquid and add to i t 2 cc. of Nessler’s solution. Any color should not be greater than t h a t obtained by treating a quantity of a nitrate containing 0.030 mg. of nitrogen (N) exactly as the 1 gram of sample was treated. Phosphate-Cautiously add 5 grams t o a cooled mixture of 12 cc. of nitric acid and 50 cc. of water and evaporate to dryness on the steam bath. Take up in 50 cc. of water and 5 cc. of nitric acid, and nearly neutralize the acid with ammonium hydroxide. Add 50 cc. of ammonium molybdate solution, shake (at about 40’ C.) for 5 minutes, and allow to stand one-half hour. Any precipitate formed should not be greater than is produced when a quantity of an alkali phosphate containing 0.025 mg. of phosphate (PO4 is treated according t o the above procedure. SuljafcDissolve 20 grams in 150 cc. of water, boil down to about 90 cc., cool, neutralize with hydrochloric acid, and add an excess of 1 cc. Filter if necessary, heat the filtrate t o boiling, add 5 cc. of 10 per cent barium chloride solution, heat on the steam bath for 2 hours, and allow to stand overnight. If a precipitate is formed, filter, wash, ignite, and weigh. The weight of the ignited precipitate should not exceed 0.0005gram. Heavy MetalsCarefully add 2 grams t o a mixture of 5 cc. of hydrochloric acid and 15 cc. of water and evaporate to dryness on the steam bath. Take up the residue in 25 cc. of water and pass hydrogen sulfide through the solution. Any brown color should not be greater than is produced by 0.04 mg. of lead under the same conditions. Iron-Carefully add 1 gram to a mixture of 2 cc. of nitric acid and 10 cc. of water and evaporate to dryness. Treat the residue with 2 cc. of hydrochloric acid and 10 CC. of water, warming slightly. Cool, dilute to 20 cc. and add 1 cc. of 10 per cent ammonium thiocyanate. Any red color should not be greater than is produced by 0.03 mg. of ferric iron under the same conditions.
S o d i u m Phosphate, Dibasic (Disodium Hydrogen Phosphate) RZQUIREMBNTS
Insoluble Matfer-Not
more than 0.005 per cent. Neulrality-To pass test. Chloride (C1)-Not more than 0.001 per cent. Nitrogen Compounds (as N)-Not more than 0.001 per cent. Sulfate (SOa)-Not more than 0.010per cent. Arsenic (As)-Not more than 0.0005 per cent. Heawy M e t a l s T o pass test (limit 0,001per cent as lead). Iron (Fe)-Not more than 0.001 per cent.
TESTS Insoluble Matter-Dissolve
10 grams in 100 cc. of water, allow to stand on t h e steam bath for 1 hour, filter through asbestos in a Gooch crucible, dry at 105’ t o llOo C., and weigh. The weight of the residue should not exceed 0.0005 gram. Neulrality-Dissolve 3 grams in 30 cc. of water a t 15’ C. and add 3 drops of phenolphthalein solution. A red color should be produced which should be discharged by the addition of 0.6 cc. of N hydrochloric acid. Boil t h e solution for 2 minutes, cool to 15’ C., and dilute t o the original volume with cold water. No pink color should appear. Chloride-Dissolve 2 grams in 20 cc. of water, add 3 cc. of nitric acid and 1 cc. of 0.1 N silver nitrate. Any turbidity should not be greater than is produced b y 0.02 mg. of chloride ion in an equal volume of solution with the quantities of acid and silver nitrate used in the test. Nitrogen Compounds-Dissolve 2 grams in 30 cc. of water, add 20 cc. of 10 per cent sodium hydroxide solution and 0.5 gram of aluminum wire in small pieces. Allow to stand for 3 hours protected from loss or access of ammonia. Decant 25 cc. of the clear liquid and add 2 cc. of Nessler’s solution. The color sbould not be more than is produced in a similar aliquot of a solution obtained by treating a quantity of an ammonium salt containing 0.02 mg. of nitrogen with the quantity of water and reagents used in the test. Sulfate-Dissolve IO grams in 100 cc. of water, add 5 cc. of hydrochloric acid and heat to boiling. Add 5 cc. of 10 per cent barium chloride, heat on the steam bath for 2 hours, and allow t o stand overnight. If a precipitate forms, filter, wash, ignite, and weigh. The weight of the ignited barium sulfate should not exceed 0.0025 gram. A r s c n i c D e t e r m i n e on a 2-gram sample b y the modified Gutzeit method. Hcaoy Metals-Dissolve 5 grams in 40 cc. of water, render neutral t o litmus paper, add 1 cc. of hydrochloric acid and 5 cc. of hydrogen sulfide water, and dilute t o 100 CC. Any brown color should not be more than is produced b y 0.05 mg. of lead in the same volume of a solution containing t h e quantities of hydrogen sulfide and excess hydrochloric acid used in the test. Iron-Dissolve 5 grams in 100 cc. of water. Dilute 10 CC. of the solution t o 40 cc., add 1 cc. of ammonium hydroxide and 5 cc. of hydrogen sulfide water. Any green color should not be greater than is produced b y 0.005mg. of iron in an equal volume of alkaline solution when 5 cc. of hydrogen sulfide water are added.
Vol. 19, No. 12
S o d i u m Sulfide REQUIREMENTS Appearance-Crystals, colorless or with no more than a slight yellow color. Ammonium Comgounds (as N)-Not more than 0.002per cent. Sulfite, Thiosulfate-To pass test (limit about 0.10 per cent Son). Iron (Fe)-To pass test.
TESTS Ammonium Compounds-Dissolve 2 grams in 80 cc. of water, add a solution of 3.5 grams of lead acetate in 20 cc. of water, and allow the precipitate t o settle. Decant 50 cc., add an excess of sodium hydroxide and water to make 100 cc. Distil off 50 cc. and add to the distillate 2 cc. of Nessler’s solution. The color should not be more than is produced by a quantity of an ammonium salt containing 0.02 mg. of nitrogen, after correction is made for nitroaen in the lead acetate, sodium hydroxide, and water used in the test. SuWte, Thiosulfate-Dissolve 3 grams in 200 cc. of water free from oxygen and add a solution of 5 grams of zinc sulfate in 100 cc. of water free from oxygen. Shake well, allow t o stand half an hour, filter, and titrate 100 cc. of the filtrate with 0.1 N iodine solution, using starch indicator. Not more than 0.3 cc. of the iodine solution should be required. Iron-Dissolve 5 grams in 100 CC. of water. The solution should be clear and colorless.
S t a n n o u s Chloride REQUIREMENTS
Solution-To pass test. Sulfate (SO*)-To pass test (limit about 0.003 per cent). Arsenic (As)-To pass test (limit about 0.0002 per cent). Substances Not Precipitated by Hydrogen Sul fide-Not 0.050 per cent as sulfates. Iron (Fe)-Not more than 0.003per cent. Other Metals (as lead)-Not more than 0.02 per cent.
more than
TESTS Solution-Heat 5 grams to 40’ C. in a mixture of 5 cc. of water and 5 cc. of hydrochloric acid. The salt should dissolve completely. Sulfate-Dissolve 5 grams in 5 cc. of hydrochloric acid, dilute the solu tion to 50 cc., heat to boiling, add 5 cc. of 10 per cent barium chloride solution, and allow t o stand overnight. N o precipitate should be formed. Arsenic-Dissolve 5 grams in 10 cc. of hydrochloric acid, bring t o a boil, and allow t o stand for 1 hour. The solution should be no more colored than a freshly prepared solution of 5 grams in 10 cc. of hydrochloric acid. Substances Not Precipitated by Hydrogen Sulfide-Dissolve 4 grams in 10 cc. of hydrochloric acid, dilute to 200 cc., and precipitate the tin with hydrogen sulfide. Filter and evaporate 100 cc. of the filtrate t o a few cubic centimeters, add a few drops of sulfuric acid, evaporate t o dryness, ignite gently, and weigh. The weight of the residue should not exceed 0.0010 gram. Iron-Warm the residue obtained in the previous test with 1 cc. of hydrochloric acid and a small crystal of potassium chlorate till chlorine is no longer evolved. Dilute with 20 cc. of water, add 2 cc. of hydrochloric acid and 1 cc. of 10 per cent ammonium thiocyanate solution. The red color should not be greater than is produced by 0.06 mg. of iron under t h e same conditions. Other Melals (as lead)-Dissolve 1 gram in a mixture of 2 cc. of hydrochloric acid and 3 cc. of nitric acid. Boil till solution is complete and brown fumes are no longer given offin abundance. Cool, dilute t o 10 cc., take 6 cc., and add 10 per cent sodium hydroxide solution till the precipitate first formed is redissolved. Cool, dilute to 40 cc., and add 10 cc. of hydrogen sulfide water. Any brown color should not be greater than is produced b y 0.10 mg. of lead in 40 cc. of an alkaline solution t o which 10 cc. of hydrogen sulfide water are added.
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Correction for Published Specification1 SODIUM BISMUTRATE Assay-Not 1
less than 75 per cent NaBiOs.
THISJOURNAL, 19, 649 (1927).
Agreement on Shellac Label The word “shellac” shall not be used by itself as a designation for material containing less than 100 per cent shellac gum cut in alcohol, t h e Federal Trade Commission stated in announcing settlement by stipulation of cases against three chemical firms. If the gum is contained in the material, but in quantities less than 100 per cent cut in alcohol, the designation “shellac compound’’ must be used.
