98 



CHEMICAL STATICS 



hold the paracasein in solution. We have seen that the proportion 

 of alkali which just suffices to hold casein in solution in water is 

 about 11.25 X 10~^ equivalents per gram. Paracasein, however, 

 requires exactly double this proportion of alkali to hold it in 

 solution (57) indicating, as Van Slyke and Bosworth believe, that 

 the molecule of paracasein is one-half the weight of the molecule 

 of casein. From this it would follow that the molecule of para- 

 casein contains but one atom of phosphorus (58). 



4. The Compounds of Serum Globulin with Inorganic Acids 

 and Bases. — The compounds of the globulin which is precipi- 

 tated from diluted serum by the passage of CO2 through it, and 

 which, in the free condition, is insoluble in distilled water, have 

 been extensively studied by W. B. Hardy (15). This investigator 

 has measured the quantities of various acids which are required 

 to dissolve one gram of globulin at various concentrations. The 

 mean values, measured in gram molecules, taking the quantity of 

 HCl required to dissolve one gram of the globulin as unity, are 

 quoted below: 



H2SO4 1.91 



Tartaric 1.994 



Oxalic 1.9 



Citric 3 



H3PO4 2.9 



H3BO3. . . .very great 

 excess 



HCl 1.0 



HNO3 0.995 



CHCI2COOH 1.0 



CH2CICOOH 1.05 



HCOOH 1 . 25 



CH3COOH 5.2 



CH3CH2COOH...7.56 



It is evident that the acid-equivalent of serum-globulin is the 

 same for all of the strong monobasic acids investigated, although 

 it is much higher for the weak acids. This equivalent is, for one 

 gram of the protein, about 18 X 10~^ gram-equivalents (mean 

 value). It is, however, somewhat higher the more dilute the 

 globulin, and this effect is more marked with the weak than with 

 the stronger acids. Thus: 



