PRODUCTS OF HYDROLYSIS 



59 



Seventeen of the twenty-six proteins given in this table contain an 

 amount of bases in which the nitrogen does not fall below 90 nor above 

 1 10 per cent, of that precipitated by phosphotungstic acid. Three of 

 the others show differences which are relatively great though absolutely 

 small ; but as they contain very little base these differences are un- 

 questionably caused by unavoidable errors of analysis ; for the phos- 

 photungstates of the bases are somewhat soluble, and, therefore, when 

 the amount of base is small the nitrogen precipitated by this acid is 

 less than that actually contained in them. On the other hand, the 

 bulky precipitate of the phosphotungstates, which is obtained when the 

 amount of base is large, carries with it some of the mono-amino-acids, 

 thereby compensating the error caused by solubility. The six remain- 

 ing proteins yield a quantity of bases containing an amount of nitrogen 

 less than that precipitated by phosphotungstic acid by a little more 

 than 10 per cent, of the latter. Two of these, namely, phaseolin and 

 legumelin from the pea, yield more bases when hydrolysed for twenty- 

 four hours than when hydrolysed for twelve hours, hence this difference 

 may possibly be due to an incomplete hydrolysis even after this longer 



