® 
W. J. Crozier — 467 
at higher concentrations, appears, then, to be somewhat more rapid 
than its ionization would demand. 
The figures in Table I show that at dilutions above 0.01 n the 
penetration of phosphoric acid is not detectable with the tissue 
used. It requires an external concentration of 0.01 N acid to 
affect color transition. In favorable cases it is found that this 
color transition occurs in about 18 minutes. If this limiting con- 
centration is subtracted from all higher concentrations studied, a 
truer idea is obtainable of the real penetrating ability of the acid. 
It is necessary also to subtract from the reciprocal of each ob- 
served penetration time the reciprocal of that for the limiting 
quantity of acid. This reduction is carried out in Table III. 
The same procedure has been used with data previously obtained 
for other acids, and leads to some interesting conclusions; it is 
believed to yield information concerning the primary action of 
acids upon the surfaces or outer layers of cells, and in the case 
of strong acids it can be shown that the peculiarities of their 
relations depend upon reactions with proteins. 
TABLE III. 
The corrected concentrations and speeds of penetration for H;PO, 
1 
(27°). Concentration, N; speed, sath De 10R 277). 
Concentration. 
1,000 
Nominal. Corrected. SAG 
1.34 1.33 398.5 
0.67 0.66 215.5 
0.134 0.124 148.5 
0.067 0.057 111.5 
0.0134 0.0034 20.4 
0.010 — — 
0.007 = a 
Fig. 3 exhibits the penetration relations of phosphoric acid as 
shown in the corrected data (Table III); measurements with HCl 
are included for comparison. The significant feature of these 
curves lies in the fact that they are composed of two straight lines, 
representing the respective predominance of two different proc- 
