Manual of chemical analysis as applied to the examination of medicinal chemicals : a guide for the determination of their identity and quality, and for the determination of their identity and quality, and for the detection of impurities and adulterations : for the use of pharmaceutists, physicians, druggists, and manufacturing chemists, and of pharmaceutical and medical students . equired, about 30 grains of the crys-tallized sodium sulphate are dissolved in one drachm of warmwater in a wide test-tube ; half a fluidounce of concentratedhydrochloric acid is added, and a strip or roll of bright
Manual of chemical analysis as applied to the examination of medicinal chemicals : a guide for the determination of their identity and quality, and for the determination of their identity and quality, and for the detection of impurities and adulterations : for the use of pharmaceutists, physicians, druggists, and manufacturing chemists, and of pharmaceutical and medical students . equired, about 30 grains of the crys-tallized sodium sulphate are dissolved in one drachm of warmwater in a wide test-tube ; half a fluidounce of concentratedhydrochloric acid is added, and a strip or roll of bright copper-foil completely immersed in the fluid ; the tube is then dippedinto boiling water and allowed to stand in the water for half anhour. The copper must remain bright; a grayish-black coat-ing would indicate arsenic. Sulphite and hyposulphite may be detected in a solution ofone part of the salt in three parts of water, by mixing it withone-third of its volume of concentrated hydrochloric acid, andheating it gently with a few grains of granular zinc ; the pres-ence of either of the above salts will give rise to the formationof hydrosulphuric acid, which may be recognized by placing a SODIUM. 349 small bunch of cotton, moistened with solution of plumbic ace-tate, in the oritice of the tube, or hy closing it with bibulouspaper moistened with the plumbic solution (Fig. 89).. Fig. 89. A black coloration of the solution would show the presenceof either or both the above salts. 350 MANUAL OF CHEMICAL ANALYSIS. SODH SULPHIS. SODIUM SEU NATRIUM SULPHUROSUM. Sulphite of Sodium. Sodium Sulphite. Colorless, opaque, prismatic crystals, containing sevenmolecules (50 per cent.) of water of crystallization ; on expos-ure to the air they effloresce somewhat, and the salt is gradu-ally converted into sulphate, emitting a feeble odor of sulphur-ous acid. This liability to decomposition is retarded, alid thesalt made more permanent, by exsiccating it at a gentle heat,when it undergoes aqueous f
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