138 



Mr. W. Sutherland. 



[July 26, 



to dissolve all the globulin by itself, hence we may say that of the total 

 solvent power of the salt and the acid b, the salt and acid possess the fractions 

 1/(1 + b/a) and (h/a)/(l-\-b/a) respectively. So if p m is the maximum 

 fraction of the globulin precipitated by h, then 1 — p m is the fraction 

 held in solution by acid, and the fraction held in solution by the salt is 



1 — f m 



1 + b/a ' 



Hence, by the presence of the acid b the salt is deprived of 

 l—(l—p m )/(l + b/a) of its solvent power, and this gives us a measure 

 of the inhibition. The amount of acid required to inhibit all the salt will 

 be &-r-{l— (1— p m )/(l + &/«)}. But to dissolve all the globulin as well as 

 to inhibit the salt we shall need an additional a of acid. Let r be the 

 total experimental amount of acid that will just give a clear solution again, 

 then 



l-(l-p m )/(l + b/a) + a = r - (9> 



This is an equation for calculating a from the observed values of p m , b, 

 and r. For a solution containing 0*005 gramme of NaCl per cubic centi- 

 metre, with HC1 and H 2 S0 4 . as acids, Mellanby found p m = 0*15 and 

 b = 2*5, while r = 7*3. Solving (9) for the positive root of a, we get 

 a = 2*8. From all his data the following table has been prepared for four 

 salt solutions of the strength specified : — 



Table V. 





NaCl 



0*5 



per cent. 



Na 2 S0 4 



0-5 

 per cent. 



MgS0 4 



0-3 

 per cent. 



MgCl 2 



0-3 



per cent. 



10 2 p m 



105 



15 

 25 

 73 



28 



9 

 45 

 90 

 25 



17 



40 



100 



7 

 39 

 fi7 



10r 



10a 



39 1 fi 









These strengths of solutions dissolve nearly equal amounts of globulin 

 in 10 c.c, but not quite equal. If we calculate the relative amounts of 

 globulin by the principles of Section 1, we find that they are as 1*7, 2*1, 2"0, 

 and 1*9. Hence, relative values of a, referred to equal amounts of globulin, 

 will be derived from the values of 10a in the table by dividing by these 

 numbers, giving 17, 11*4, 17*5, and 9. Now these are to one another 

 nearly as the values of 10 2 j? m in the table, a fact which confirms in a general 

 way the above reasoning and calculation, though, strictly, instead of comparing 



