GENERAL CHEMICAL CHARACTERS OF PROTEINS 53 



with phenol phthalein, and only slightly depresses the orange tint of 

 methyl orange. Such a reaction might be due to the carbonic acid 

 held in combination by the protein. 



On titration with alkalis in the presence of phenol phthalein certain 

 marked phenomena were observed. It was noticed that just half as 

 much sodium hydroxide or potassium hydroxide was necessary to 

 produce solution as was necessary to produce a permanent red solu- 

 tion ; in the case of barium hydroxide, on the other hand, the point 

 of solution and the point of neutralisation to phenol phthalein coin- 

 cided. These facts suggest that globulin has two replaceable hydro- 

 gens, and can form acid salts, of which those of sodium and potassium 

 are soluble, and that of barium insoluble. The same relative amount 

 of ammonia as of sodium and potassium hydroxide is necessary to 

 produce solution ; as might be expected, however, the neutralisation 

 point with phenol phthalein is somewhat indeterminate. It was found, 

 as a general result of the neutralisation method, that 10 x 10 ~ 5 

 equivalents of alkali were necessary for the solution of I gram of 

 globulin, and 20 x 10 ~ 5 were necessary for neutralisation with 

 phenol phthalein as indicator ; 20 x 10 ~ 5 equivalents of strong 

 acids were also necessary to produce solution. 



It is of interest to compare those numbers with the numbers 

 obtained by Hardy for dialysed acid and alkali albumin from egg- 

 white : 



Pink to Phenol- 

 Solution, phthalein. 



Acid albumin from egg-white Na(OH) 27-3 57 



'475 gram per 100 c.c. NH 4 (OH) 29 100 



Ba(OH) 2 57 65 

 Alkali albumin from egg-white Na(OH) 36 



*3 6 3 gram per 100 c.c. NH^OH) 37 



Ba(OH) 2 77 



Here again the molecular and not the equivalent quantities of 

 base exert the same solvent action, and there is evidence of the 

 formation of acid and basic salts. 



Further investigations were made as to the acid and basic 

 functions of serum-globulin by the employment of physical methods. 



By means of conductivity methods the basicity of globulin was 



determined. The value - 1 - ^ (see Lacqueur and Sackur's work 



i 



above, p. 50) between ^ = 32 and v =32x32 was determined; as 

 a result, it was concluded that globulin is pentabasic. 



The hydrolysis of both the acid and basic salts was determined 

 by ascertaining the rate of inversion of cane-sugar, and of hydrolysis 

 of methylacetate by acids and bases in the presence of globulin salts. 

 Owing to the change of the latter in the presence of acids, no very 

 conclusive results were obtained as to the hydrolysis of the acid salts. 

 The results, such as they were, indicated under the conditions of 

 experiments a distinct amount of hydrolysis : 



Glob. HC1 + H a O = Glob. OH + HC1. 



With alkalis, under similar conditions, but little hydrolysis was 

 indicated. With a concentration of 2576 grams of globulin in a 

 litre neutralised by 17-12 x lo" 5 equivalents of NaOH for each 

 gram of globulin, the hydrolysis, as indicated by methylacetate 

 catalysis, was only o'288 per cent, *>., only 0-288 per cent, of the 



