EXAMINATION OF BLOOD. 55 



and water, and filtered. From the hsemin the hsematin may 

 be obtained by dissolving it in dilute caustic soda solution, 

 precipitating with dilute hydrochloric acid, filtering, and 

 washing. Since the quantity of the haematin thus obtained 

 is very small and sticks to the filter, it is advisable to dissolve 

 it by pouring on the filter a solution of ammonia, and then to 



FIG. 4. Hsematin it} drocnloride, Haemin Crystals, 

 evaporate this solution to dry ness on the water-bath. On 

 incinerating, the haBmatin leaves the red oxide of iron (13.5 

 per cent.). 



X. Haemin Test. 



The formation of haBmatin hydrochloride is a very excel- 

 lent means of recognizing blood-stains. Some blood, dried 

 in the air but not heated, is ground in a mortar with a trace 

 of salt, then boiled in a dry test-tube with glacial acetic acid 

 and the fluid obtained evaporated in a watch-glass on a 

 water-bath heated not quite to boiling. The test may also 

 be made on a microscope-slide. Crush some of the dry blood 

 with a knife-blade, mix it with some salt, put the cover-glass 

 on, let some glacial acetic acid flow under this, and heat the 

 slide over a very small luminous flame till the liquid just 

 begins to boil, then let some more glacial acetic acid flow on 



