FROM PROTEID SUBSTANCES. 365 



freed from all traces of barium by cautious addition of dilute 

 sulphuric acid, was concentrated to a syrup and the peptone 

 precipitated by alcohol. The product was purified somewhat 

 by repeated boiling with alcohol and thorough extraction with 

 ether. 



In the production of a melanin 90 grams of this hemipep- 

 tone were boiled for 98 hours with 2 litres of 10 per cent sul- 

 phuric acid. The fluid rapidly became black in color, and 

 gradually there occurred a small separation of a black pigment. 

 There was also noticeable, especially toward the end of the 

 boiling, the odor of volatile fatty acids, and some slight crys- 

 tallization of fatty acids upon the walls of the condenser could 

 be detected likewise. There was however no evidence of the 

 splitting off of free sulphur, so conspicuous with antialbumid. 

 At the expiration of the 98 hours, the fluid was cooled, and 

 the melanin-like substance collected by filtration. The very- 

 dark filtrate on standing and concentrating continued to 

 deposit small portions of black pigment, the process being 

 repeated until several fractions were obtained. The fluid, 

 however, still gave evidence of the presence of considerable 

 pigment in solution. The united fractions of pigment were 

 washed thoroughly with water, then dissolved in 0.2 per cent 

 solution of potassium hydroxide and the filtered fluid precipit- 

 ated by neutralization with 0.2 per cent hydrochloric acid. 

 The pigment was next washed free from soluble salts with 

 water and extracted with alcohol and ether. When freshly 

 precipitated, this melanin, unlike that prepared from antialbu- 

 mid, was somewhat soluble in water, but if allowed to dry 

 upon the filter it could be washed with water without loss. 

 The amount of pigment obtained was 0.9 gram, equal to 1.0 

 per cent of the original hemipeptone. 



When dried at 105 C. until of constant weight, it gave on 

 analysis the following results : 



I. 0.2436 gram substance gave 0.0815 gram H 2 O = 3.72 per cent H and 



0.5156 gram CO 2 = 57.75 per cent C. 



n. 0.2068 gram substance gave by the Kjeldahl method 0.01986 gram 

 N = 9.60 per cent N. 



