348 THE BLOOD. 



chloride and dissolved in glacial acetic acid. On heating, the 

 hsemin is precipitated in the form of very characteristic, drawn- 

 out, rhombic platelets, which are insoluble in water, alcohol, and 

 ether, with difficulty so in glacial acetic acid and in dilute mineral 

 acids, but are readily soluble in dilute alkaline solutions and acid 

 alcohol. The crystals are collected on a filter, washed with alcohol 

 and ether, and are thus obtained in pure form. To prepare the 

 hsematin, the hsemin is dissolved in a dilute solution of sodium 

 hydrate and supersaturated with dilute hydrochloric acid. The sub- 

 stance is thus precipitated in the form of brownish flakes, which are 

 washed free from chlorides and dried at 120 C. Hsematin, in con- 

 tradistinction to oxyhsemoglobin and hsemin, is non-crystallizable. 

 Its solubility is essentially the same as that of hsemin. In acid solu- 

 tion both hsematin and hsemin show a well-defined spectral band 

 between C and D. Between D and F a second band is seen, which 

 is much wider but less sharply defined than the first. By diluting 

 the solution this band may be resolved into three bands, of wnich 

 one is located between b and F, near F ; another, between D and E, 

 nearer E ; and a third faint band between D and E, nearer D. As 

 a rule, however, only two bands are seen. The alkaline solutions of 

 hsematin are distinctly dichrotic and give only one band of absorp- 

 tion, the greater portion of which lies between C and D, and extends 

 slightly beyond I). 



The basis of the hsematin molecule is supposedly a methyl-propyl- 

 pyrrol (hsemopyrrol) : 



CH 3 C C-CH 2 .C 2 H 5 



' II II (C 8 H 13 N) 



HC\ /CH 



H 



This is probably the mother-substance of the hsematinic acids 

 which Kuster obtained from hsematin on careful oxidation. One of 

 these is the dibasic acid, CgHgNO^, while the other may be regarded 

 as the anhydride of the tribasic acid, C 8 H 8 O 5 , which in turn through 

 loss of CO 2 can be transformed into the anhydride of methyl- 

 ethyl maleic acid, C 7 H 8 O 3 . The structural formulse of these acids, 

 according to Kuster, are the following : 



C-CH 2 .CH 2 COOH 

 | (C 8 H 9 N0 4 ) 



C CH 2 CH 2 COOH 

 I (C 8 H 8 5 ) 



/C 



aci( 

 iron 



On treating with concentrated sulphuric acid, with hydrochloric 

 id, or with glacial acetic and hydrobromic acids, hsematin loses its 

 ' and on the subsequent addition of water is transformed into 



