362 THE FORMATION OF MELANINS 



When dry, it weighed 2.728 grams. The smaller portion of 

 crude melanin was dissolved in 0.2 per cent solution of 

 potassium hydroxide and the clear filtered solution precipi- 

 tated with dilute hydrochloric acid, etc., as just described. 

 When dry this preparation weighed 0.675 gram. Hence, the 

 total yield of melanin insoluble in the 10 per cent sulphuric 

 acid amounted to 3.403 grams, or 5.5 per cent of the original 

 antialbumid. 



The melanin formed in this decomposition the portion 

 which had been purified by solution in dilute ammonia 

 gave on anatysis the following results, after being dried at 

 105 C. 



I. 0.3140 gram substance gave 0.2130 gram HgO = 7.63 per cent H and 



0.6631 gram CO. a = 57.60 per cent C. 

 IL 0.2012 gram substance gave 0.1300 gram H..O = 7.17 per cent H and 



0.4267 gram C0 a = 57.85 per cent C. 

 HL 0.2247 gram substance gave by the Kjeldahl method 0.02671 gram N = 



11.88 per cent N. 



IV. 0.2245 gram substance gave 0.02656 gram N = 11.83 per cent N. 

 V. 0.5479 gram substance gave by fusion with NaOH and KNO, 0.1749 



gram BaS0 4 = 4.39 per cent S. 

 VL 0.4050 gram substance gave by fusion with NaOH and KN0 8 0.1258 



gram BaS0 4 = 4.27 per cent S. 

 VTL 0.4616 gram substance gave 0.0025 gram ash = 0.64 per cent. 



PERCENTAGE COMPOSITION OF THE ASH-FREE SUBSTANCE. 



100.00 



The smaller fraction of this same melanin which had been 

 purified by solution in 0.2 per cent potassium hydroxide con- 

 tained the following percentages of nitrogen and sulphur : 



0.2046 gram substance gave by the Kjeldahl method 0.02379 gram N = 11.63 



per cent N. 

 0.4070 gram substance gave by fusion with NaOH and KNO, 0.1272 gram 



BaSO 4 = 4.29 per cent S. 



