2360 ‘REPORT OF THE CHEMIST OF THE 
In the tables following, the concentration of acid in the solutions 
is given in terms expressing the number of cc. of N-1000 acid 
equivalent to I cc. of solution used. The concentration of acid in 
the casein is given in terms expressing the number of cc. of N-1000 
taken up by I gram of casein. 
In the third column, the figure representing the amount of 
N-1000 acid in I cc. of solution given for zero time indicates the 
exact concentration of the acid used in the series, as determined by 
measurement of its conductivity. This value generally differs 
slightly from the figures corresponding to the normality given in 
the first column, because the stock solutions usually possessed 
factors varying somewhat from unity. 
In the fourth column (concentration of acid in casein), the 
amount of acid taken up by I gram of casein in each case is calcu- 
lated from the difference between the original concentration of the 
aqueous solution of acid and its concentration after contact with 
‘casein for the time stated, as in Table IV. The calculation is based 
DXxV 
'_, in which C represents the concentra- 

upon the formula C= 
tion of acid in casein; Bae decrease in concentration of acid in 
aqueous solution caused by contact with casein; V, the volume of 
the solution; and g, grams of casein used. 
In the sixth column, the figures express the ratio of the amount 
of acid in I gram of casein to the amount of acid in 1 cc. of the sur- 
rounding solution at the end of the period during which the acid 
and casein were in contact. 
