Text-book of medical and pharmaceutical chemistry . lution of sodium hypochlorite, is probably one of these spots with nitric acid, when it should dis-appear ; evaporate the acid over a lamp, moisten the spot with ARSENIC. 189 water, and hold the dish over a vessel containing sulphurettedhydrogen, prepared by the action of sulphuric or hydrochloricacid upon sodium or potassium sulphide. If the stain was dueto arsenic the spot will turn lemon-yellow. The antimonymirror is insoluble in sodium hypochlorite (Labarraques solu-tion) and after treatment as above gives an orange stain.
Text-book of medical and pharmaceutical chemistry . lution of sodium hypochlorite, is probably one of these spots with nitric acid, when it should dis-appear ; evaporate the acid over a lamp, moisten the spot with ARSENIC. 189 water, and hold the dish over a vessel containing sulphurettedhydrogen, prepared by the action of sulphuric or hydrochloricacid upon sodium or potassium sulphide. If the stain was dueto arsenic the spot will turn lemon-yellow. The antimonymirror is insoluble in sodium hypochlorite (Labarraques solu-tion) and after treatment as above gives an orange stain. Nowsoften the glass, bend the delivery tube downward and let it dipinto a solution of AgNOs; after an hour, pour some very weaksolution of NH^OH upon the surface of the AgNOj precipitate at line of separation = arsenic. If the sub-stance to be tested is a solid, a small portion of it may be thrownupon a glowing charcoal, when arsenic, if present, will give anodor resembling garlic. These tests will be sufficient to enable Fig. the physician to decide upon the presence of arsenic during thelife of the patient, and guide him in his treatment and Test.—Heat to boiling in a test tube, a strongsolution of potassium hydroxide, in which some pieces ofzinc or aluminium have been placed. Add a drop or two ofthe suspected solution, spread a cap of filtering paper over themouth of the tube, and moisten it with a little nitrate of silversolution. A brown or black stain of metallic silver will appearupon the paper, if arsenic is present. The arsenous oxide is de-composed, and the nascent hydrogen combines with the arsenicand forms arsine AsH,, which reacts with the silver nitrate,reducing it to metallic silver. This test is very valuable, enablingthe analyst to distinguish between arsenic and antimony, whichlatter does not give the above reaction. 190 MEDICAL CHEMISTRY. Sulphuretted hydrogen H.,S passed into an acidulated solutioncontaining arseni
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