SUMMARY 103 



just hold one gram of edestin in solution is equivalent to the 

 quantity of acid with which it combines to form Osborne's "edes- 

 tin monohydrochloride," that is, 7 X 10^^ equivalents. Hence the 

 ratio of the alkali- to the acid-equivalent at " saturation " is 1 : 2. 



From the observations of Osborne it would appear that acids 

 dissolve edestin, as they do serum-globulin, in molecular propor- 

 tions, not in equivalent molecular proportions. 



Osborne has also determined the hydrochloric acid equivalents 

 at neutrality to tropceolin (IQ-^ to IQ-^ H+ according to Salm 

 (48)), of a variety of vegetable proteins. That of edestin was 

 found to be 127 X 10"^ gram-equivalents per gram, of excelsin 

 124 X 10-^ of legumin 129 X 10"% of amandin 103 X 10"^ of 

 crystaUized egg-albumin 90 X 10"^ in the same units. Recol- 

 lecting that these determinations are made in the presence of a 

 considerable excess of acid they may be considered as furnishing, 

 possibly, a measure of the constant maximum acid-equivalents of 

 these proteins in the presence of excess of acid. However this may 

 be, it is evident that the acid-equivalent of edestin increases very 

 considerably with the acidity of its solution. 



The compounds which edestin and gliadin form with cupric 

 hydroxide (33) have already been discussed in Chap. I. 



7. The Compounds of Ovomucoid with Acids and Bases. — 

 These have so far chiefly been studied by electrochemical methods 

 (43). Uncombined ovomucoid is freely soluble in distilled water, 

 but on adding small quantities of acid or alkali to this solution 

 a proportion of the acid or base is neutralized by the protein. 

 Employing the potentiometric method I have shown that at neu- 

 trality to litmus (i.e., absolute neutrality) 1 gram of ovomucoid 

 neutralizes 7 X 10~^ equivalents of HCl. Its basic function, there- 

 fore, predominates over its acid function. 



The maximum (constant) combining-capacity of ovomucoid for 

 KOH, in solutions containing excess of the base, is about 50 X 10~^ 

 equivalents per gram. 



The maximum combining-capacity of ovomucoid for HCl was 

 not attained in any of the solutions investigated, but is probably 

 in excess of 100 X 10~^ equivalents per gram. 



In the chapters dealing with the electrochemistry of the proteins 

 the reader will find a more detailed discussion of these compounds. 



8. Summary of Some of the Results Cited in this Chapter. — 

 Some of the more important determinations which have been cited 

 in this chapter are summarized in the following table: 



