238 H^EMIN. 



been employed 1 , of which the most recent, said to yield 5 gr. of crystals 

 from each 1 litre of blood, is as follows 2 . To each volume of de- 

 fibrinated and strained blood add four volumes of glacial acetic acid 

 previously warmed to 80. As soon as the temperature of the mixture 

 has fallen to 55 60, it must be again warmed to 80. On cooling 

 and standing for 10 12 hours crystals separate out; the supernatant 

 liquid is then removed by a syphon, the crystals are washed with water 

 repeatedly by decantation in a tall glass cylinder and are finally 

 collected on a filter and washed with water, alcohol and ether. 



The successful preparation of haemin crystals from minute quantities 

 of haemoglobin or methsemoglobin is of the greatest importance for 

 medico-legal purposes, since they suffice, even in the absence of all other 

 confirmatory evidence, to establish the nature of the material used in 

 their preparation. In the detection of blood-stains it is usual first to 

 examine with a spectroscope an aqueous solution of the colouring 

 matter if it can be obtained, for the characteristic absorption bands 

 of oxy-haemoglobin or metheemoglobin. In old stains the haemoglobin 

 is frequently decomposed, in which case it is insoluble in water, and 

 alkaline extracts must be made and examined for the spectra charac- 

 teristic of hsematin. The residues from the spectroscopic examination 

 are lastly used to prepare haemin crystals, in final confirmation of the 

 evidence previously obtained 3 . 



Allusion has already been made (see p. 235) to some work on haemin and 

 hsematin which assigns to these substances a composition and relationship very 

 different from those usually accepted, and further puts the relationship of the 

 colouring matter of blood to the bile-pigments in a new light 4 . With the prelimi- 

 nary caution that these views are not as yet generally accepted and require confirma- 

 tion they may be briefly dealt with here. Using amyl-alcohol in the preparation of 

 haemin crystals it is stated that the crystals have the following composition 

 (C 32 H 3e N 4 Fe0 3 . HC1) 4 C 5 H 9 .OH. The group C 32 H 30 N 4 Fe0 3 is regarded as the true 

 hasmin, Teichmann's crystals consisting of C 32 H 30 N 4 Fe0 3 . HC1. When the crystals 

 thus prepared are decomposed by caustic alkalis as in the ordinary method for pre- 

 paring haematin from them, the hasmin is supposed to take up one molecule of water 

 and yield hasmatin C 32 H 32 N 4 Fe0 4 . By treating this haematin with strong sulphuric 

 acid, it loses its iron and uniting with oxygen yields haematoporphyrin or iron-free 

 haematin, C 32 H 32 N 4 5 , which is however further regarded as derived by dehydration 

 from a true haematoporphyrin whose composition is C 16 H 18 N 2 3 . The latter is thus 



1 See Gamgee, Physiol. Chem. Vol. i. p. 116, or Hoppe-Seyler, Physiol. pathul.- 

 chem. Anal. Aufl. 5, 1883, S. 241. 



2 Schalfejew, Jn. d. russ. phys.-chem. Gesell. 1885. See Abstr. in Ber. d. d. 

 chem. Gesell. xvm. Bd. (1885), Kef., S. 232. 



3 For details see Hoppe-Seyler, loc. cit. S. 529. Gamgee, loc. cit. p. 217. 

 MacMunn, The spectroscope in medicine, 1883, pp. 130 148. 



4 Nencki u. Siebef, Ber. d. d. chem. Gesell, Bd. xvii. (1884), S. 2267, xvm. 

 S. 392, Arch.f. exp. Path. u. Pharm. Bd. xvm. (1884), S. 401, Bd. xx. (1886), S. 325. 

 Bd. xxiv. (1888), S. 430. Nencki u. Eotschy. Monatshf. f. Chem. Bd. x. (1889), 

 S. 568. See also Hoppe-Seyler in adverse criticism, Ber. d. d. chem. Gesell. Bd. xvm. 

 (1885), S. 601, Zt. f. physiol. Chem. Bd. x. (1886), S. 331. 



