A laboratory manual of physiological and pathological chemistryFor students in medicine . ysaturated with salt,,are heated in a flask on the water-bathto 90°, then 25 cc. of blood are added quite gradually andwith constant shaking; continue the heating at 90° for aboutten minutes, then pour into a beaker and let stand for twenty-four hours. The hsemin will be found on the bottom of thebeaker in the form of an intensely bluish-black layer of ght-tering crystals. (Examine under the microscope.) The supernatant fluid is siphoned off, the crystals arewashed once with glacial acetic acid, then with
A laboratory manual of physiological and pathological chemistryFor students in medicine . ysaturated with salt,,are heated in a flask on the water-bathto 90°, then 25 cc. of blood are added quite gradually andwith constant shaking; continue the heating at 90° for aboutten minutes, then pour into a beaker and let stand for twenty-four hours. The hsemin will be found on the bottom of thebeaker in the form of an intensely bluish-black layer of ght-tering crystals. (Examine under the microscope.) The supernatant fluid is siphoned off, the crystals arewashed once with glacial acetic acid, then with acetic acid ^ Nencki calls this substance acethsemin and gives it the formulaCs^HaaNiFeClO^.—O. EXAMINATION OF BLOOD. 55 and water, and filtered. From the hsemin the hffmatin maybe obtained by dissolving it in dilute caustic soda solution,precipitating with dilute hydrochloric acid, filtering, andwashing. Since the quantity of the ha-matin thus obtainedis very small and sticks to the filter, it is advisable to dissolveit by pouring on the filter a solution of ammonia, and then to. Fig. 4.—Hsematin Hydrochloride, Hsemin Cr\ this solution to dryness on the water-bath. Onincinerating, the hsematin leaves the red oxide of iron ( cent.). X. Haemin Test. The formation of hsematin hydrochloride is a very excel-lent means of recognizing blood-stains. Some blood, driedin the air but not heated, is ground in a mortar with a traceof salt, then boiled in a dry test-tube with glacial acetic acidand the fluid obtained evaporated in a watch-glass on awater-bath heated not quite to boiling. The test may alsobe made on a microscope-slide. Crush some of the dry bloodwith a knife-blade, mix it with some salt, put the cover-glasson, let some glacial acetic acid flow under this, and heat theslide over a very small luminous flame till the liquid justbegias to boil, then let some more glacial acetic acid flow on 56 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. from the rim, h
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