216 REPORT OF THE CHEMIST OF THE 
1.04488 (water at 4° C==1). ‘The potassium chloride had been 
recrystallized four times from solution in conductivity water and 
then finally fused. 
DATA ILLUSTRATING ACCURACY OF METHOD USED IN EXPERIMENTS. 
Results obtained by the method employed could be closely dupli- 
cated when the conditions of experiment were uniform. For ex- 
ample, four portions of 100 cc. each of N-125 lactic acid were 
treated under constant agitation for 20 minutes, each with I gram 
of casein. The percentages of acid taken up, as shown by measur- 
ing the conductivities of the filtrates, were 29.73, 29.94, 29.64 and 
29.85. The agreement of these figures may be regarded as satis- 
factory, when we consider the fact that the reaction is still proceed- 
ing quite rapidly at the end of 20 minutes and that the exact time 
of contact was not quite the same in each case, owing to the inter- 
val required for removing the flasks from the shaker and filtering. 
‘As the reaction approaches equilibrium, the proportion of error 
decreases. 
METHODS OF CALCULATING EQUIVALENT CONCENTRATIONS OF DILUTE 
ACIDS FROM CONDUCTIVITIES. 
It is important, of course, to state the results of conductivity 
measurements in terms expressing equivalent amounts of acid. 
The method of Kohlrausch,! while convenient to use when only 
a few calculations are needed, was found unwieldy for our work, 
even with the mineral acids. In the case of the weak organic 
acids, the method was practically useless, owing to the number 
of approximations required in each calculation before reaching an 
accurate result. Consequently, we worked out two simpler methods, 
one for the mineral acids and one for the organic, which enabled 
us to make the necessary calculations with comparative ease and 
rapidity. 
Method for sulphuric and hydrocloric acids— The purely graph- 
ical method is simplest in principle but involves the laborious pre- 
paration of very accurate curves. The purely mathematical cal- 
*Leit. d. Elek., p. 130. 
