520 CHEMISTRY OF THE PROTEIDS CHAP. 



Haematin forms a non-crystalline bluish-black powder, which is 

 insoluble in water, alcohol, ether, chloroform, and in watery solutions 

 of acids ; very slightly soluble in glacial acetic acid, or in alcohol or 

 ether containing HC1, but very soluble in all alkaline solutions. When 

 heated beyond 180 C. it undergoes decomposition; when incinerated 

 it gives off hydrocyanic acid, while a residue of 12*6 per cent, con- 

 sisting of pure oxide of iron, remains behind. 



On distilling carefully-dried hsematin with perfectly dry zinc dust, 

 Milroy 1 obtained three volatile substances, two of which, in their 

 spectroscopic characters resembled hsematoporphyrin and urobilin, 

 while they differed from the latter markedly in regard to their 

 solubilities. The third substance was probably allied to hsemopyrrol. 

 The products of distillation were condensed in (1) a spiral glass worm 

 surrounded by a water jacket, (2) a coiled tube placed in a mixture of 

 ice and water, and (3) the remaining gas passed through a wash-bottle 

 containing concentrated HC1. This HC1 absorbed some pigment 

 which, on spectroscopic examination, showed absorption-bands appar- 

 ently identical in position and character with those of acid hsemato- 

 porphyrin. The pigment which condensed in the tubes, dissolved in 

 chloroform with a reddish -brown colour, showed a faint green 

 fluorescence, and gave on spectroscopic examination the three bands : 



a A578 A560 

 ft A540 A430 

 y A500 A402 



After distilling off the chloroform the pigment residue was found to 

 be insoluble in caustic alkalies, soluble in concentrated HC1, but pre- 

 cipitated by dilution with water, and readily soluble' in alcohol, ether, 

 chloroform, petroleum ether, glacial acetic acid, and benzene. On 

 dissolving the pigment in ether and adding to the latter some concen- 

 trated HC1 diluted with an equal bulk of water, a brown pigment 

 passed into the ether having an absorption-band, A506 A476. 



The red watery hydrochloric acid solution showed three bands 

 closely resembling those of hsematoporphyrin : 



a A598 A588 dark 

 ft A578 A576 faint 



A578 A562 slightly fainter 

 7 A562 A538 dark 



On diluting the acid solutions, extracting the pigment with chloro- 

 1 J. A. Milroy, Proc. of Physiol. Soc. xxiv. ; Journ. of Physiol. 31. (1904). 



