igii] 



Ross Aiken Gortner 



21 I 



In Order to test the stabilitv of the melanin molecnle, I under- 

 took the isolation of the melanin from black wool, and used vary- 

 ing strengths of sodium hydroxide Solution to destroy the keratin 

 structure, keeping all other factors as nearly uniform as possible, 

 Experiments were carried out with Solutions of sodium hydroxide 

 of the strengths shown in Table i where the percent. of " pigment " 

 found and its percentage composition are tabulated. For a detailed 

 description of the methods employed the reader is referred to the 

 original article; Gortner (1910), Studies on Melanin I. 



TABLE I 



Method 



0.2 per cent. NaOH, soluble in acid 

 0.2 per cent. NaOH, insol. in acid 



I per cent. NaOH 



2.5 per cent. NaOH 



5 per cent. NaOH 



10 per cent. NaOH 



20 per cent. NaOH 



30 per cent. NaOH 



50 per cent. NaOH 



25 per cent, H2SO4 



Yield of pigment 



8.10% 



1.36 



3.26 



2.95 

 3.62 



2.43 

 1.78 



1.71 

 1.56 

 2.00 



It will be seen from this table that the use of strong alkali de- 

 composes the melanin molecule, causing a loss of both nitrogen and 

 hydrogen, and that one may obtain as many different products as is 

 desired providing that the keratin is destroyed by different concen- 

 trations of alkali. It can readily be seen how different "mel- 

 anins " have been isolated by different investigators using material 

 of similar origin. Naturally the weaker concentrations of alkali 

 cause the least decomposition so that in the future my work on 

 melanin will be carried out with sodium hydroxide in 0.2 per cent. 

 concentration. 



The nature of melanin. The pigment preparations I have iso- 

 lated were of two types. The greater portion of the product which 

 was isolated by the action of 0.2 per cent. sodium hydroxide was 

 soluble in dilute acids, while all of the other preparations were 

 insoluble products. These insoluble products formed brownish 

 black granules, powdering to a dark brown dust. They were insolu- 

 ble in indifferent solvents and in dilute acids, soluble in concentrated 



