New York AGRICULTURAL EXPERIMENT STATION. 219 
The values of A®° calculated for sulphuric and hydrochloric 
acids from the resistances given, after correcting for conductivity 
of water, agree within a fraction of a per ct. with those of Kohl- 
rausch! as corrected by the temperature coefficients of the two 
acids.” | 
Method for lactic and acetic acids— The method used in cal- 
culating the conductivity results obtaind with lactic and acetic acids 
into their acid equivalents was, like that employed for the mineral 
acids, a combination of approximate calculation and graphic cor- 
rection, the maxima of such corrections being 1.9 per ct. for acetic 
acid and 5 per ct. for lactic acid. 
The purely empirical but convenient method of approximate cal- 
culation was based on the following data: Representing the resist- 
ance of N-125 acid as R,,,, etc., it was found for lactic acid that R.,, 
Set50 Nis, While Roogg == 1.58 Riooo, intermediate ratios ranging 
between 1.50 and 1.58. The percentage increase caused by doubling 
the dilution is fairly constant, varying from 50 to 58. For acetic 
smomiien yatiation is» even less. Thus, R,.. ==,.1.44 R,,,° and 
See Tao RS Increasing by roo per ct. the dilution of any 
solution between N-125 and N-1ooo concentrations results in an 
increase of from 44 to 45 per ct. in the resistance. In general, the 
ratio between the percentage increase in dilution and the percent- 
age increase in resistance is nearly constant. This relation is ex- 
pressed by the following simple formula for use in calculation: 
(1) log x = log x, —c (log R— log R,) 
(2) = log x, —c (log k —log k,) 
These two forms allow one to calculate x from either resist- 
ance (1) or conductivity (2). The value of c is determined 
log + —log +, 
from either resistance or conductivities: c— rg ee Viera 
log k ,— log k, 

log +, — log +, 
log k — log k ¥ 
(=1 for N-1000. concentration); x,— concentration of the 
strongest solution to which the formula is applied (N-125 in 
present case) ; + ,—=concentration of most dilute solution to which 
inwwiichea == 7 10° ==-concentration sought 

*Leit. d. Elek., p. 60. 
* Ibid. p. 190. 
