THE VEGETABLE PROTEINS 



again in a neutral salt solution by any known means, is not " acid 

 albumin," for it is not soluble in a slight excess of potassium hydrate 

 solution. Similar products result from nearly all the seed proteins, and 

 their formation may be considered to be a general property of these 

 substances. As no suitable name had ever been suggested for such 

 insoluble products, the writer has proposed that they be called in 

 general proteans^ that that obtained from edestin be called edestan, and 

 that similar derivatives from other proteins be given corresponding 

 names. 



Preparations of nearly all proteins, made by the customary methods, 

 contain more or less substance of such altered solubility, and there is 

 little doubt, in view of what we have learned in regard to the forma- 

 tion of these products from edestin, that they are the result of the action 

 of a slight quantity of acid present in the solutions from which they 

 were originally obtained. The following experiments, made with 

 edestin, give the evidence on which this belief is founded. 



Several I gramme portions of neutral edestin, which contained 2*16 

 per cent, of edestan, were suspended in 10 c.c. of pure water and kept 

 at different temperatures for six hours with frequent shaking. An 

 equal volume of 20 per cent, sodium chloride solution was added and 

 the solution at once made neutral to phenolphthalein. The solution 

 was then filtered and nitrogen determined in the thoroughly washed 

 residue collected on the paper, from which the quantity of edestan was 

 calculated. 



PERCENTAGE OF EDESTAN FORMED BY CONTACT WITH WATER. 



These figures show that even at 20 the quantity of edestan which 

 is formed by water alone is twice as great as in the original prepara- 

 tion and that the quantity is decidedly greater if the water contains 

 carbonic acid. At 50 about four times as much edestan is formed as 

 at 30 and nearly eight times as much as at 20 ; showing the velocity 

 of the reaction to be doubled by each increase of 10 in the temperature. 

 In view of the larger amount of edestan produced by the water con- 

 taining carbonic acid we should expect to find that the proportion of 



