178 LECTURE VII. 



by the mineral acids, exhibit the peculiar play of colours 

 afforded by haBmatoidine. This second kind of crystals 

 has received the name of Hczmine from their discoverer 

 Teichmann. Quite recently Teichmann has himself be- 

 gun to entertain doubts as to whether it is not really a 

 sort of haematine. These forms do not present as yet 

 the slightest pathological interest, but, on the other hand, 

 they have proved of very great importance in forensic 

 medicine on account of their having been recently em- 

 ployed as one of the surest tests for the examination of 

 blood-stains. I myself have been in a position to make 

 experiments of this sort in forensic cases. For this pur- 

 pose the best mode of proceeding is to mix dried blood in 

 as compact a form as possible with dry, crystallized, 

 powdered common salt, and then to add to this mixture 

 glacial acetic acid, and evaporate at a boiling heat. 

 When this has been done, crystals of haemine are found 

 where the blood-corpuscles or the substance previously 

 lay, in which the presence of hasmatine was doubtful. 

 This is a reaction which must be ranked among the most 

 certain and reliable ones with which we are acquainted. 

 There is no other substance in which we know such a 

 transformation to take place, but hsematine. This test 

 is extremely important, because it is applicable in the 

 case of extremely minute quantities, only they must not 

 be spread over too large a surface. It would therefore 

 not be easy of application in a case where we had to deal 

 with a cloth which had been dipped into a thin, watery, 

 fluid coloured with blood. Yet I was able, in the case 

 of a murdered man, on the sleeve of whose coat blood 

 had spurted, and where some of the drops were only a 

 line in diameter, from these minute specks to produce 

 innumerable crystals of haemine, though of course micro- 

 scopical ones. In cases in which the ordinary chemical 

 tests would necessarily absolutely fail on account of the 



