48 RODNEY H. TRUE AND HARLEY HARRIS BARTLETT 
the absorption was more likely to be a mean between that of the 
unmixed constituent salts at the same total concentration. 
The present paper deals primarily with absorption from mixtures 
of three salts. Two experiments are reported, one of which was 
carried out with the nitrates of potassium, calcium and magnesium, 
the other with monopotassium phosphate, calcium nitrate and mag- 
nesium sulphate. In each experiment 36 culture solutions were used, 
the uniform concentration of which was 140 N X io~^. Mono- 
Table I. 
Composition 
Daily Concentration 
KNO3 
Ca(N03)2 
Mg(N03)2 
I 
2 
3 
4 
140 NXio~^ 
0 NXio~6 
0 NXio~6 
1. 000 
1-033 
1.043 
1.077 
1.086 
120 " 
20 " 
0 " 
1. 000 
1.027 
1.036 
1.037 
1.036 
120 " 
0 " 
20 " 
1. 000 
1.027 
1.043 
1.048 
1.040 
100 " 
40 
0 " 
1. 000 
1.032 
1.045 
I.OI8 
1.02 1 
100 " 
20 " 
20 
1. 000 
1.063 
I. on 
0.934 
0.894 
100 " 
0 " 
40 
1. 000 
1.048 
1.054 
1.039 
1.022 
80 
60 
0 " 
1. 000 
1. 06 1 
1.087 
1.059 
1.038 
80 " 
40 
20 " 
1. 000 
1.065 
1.073 
1.039 
1. 019 
80 
20 " 
40 
1. 000 
1. 041 
1.052 
1.042 
1.036 
80 
0 " 
60 
1. 000 
1. 041 
1-057 
1.046 
1.030 
60 
80 
0 " 
1. 000 
1.038 
1-053 
1.034 
1.029 
60 
60 
20 " 
1. 000 
1.065 
1-035 
0.943 
0.878 
60 
40 
40 
1. 000 
I.06I 
I.OOI 
0.901 
60 
20 " 
60 
1. 000 
1. 061 
1.073 
1.023 
1.003 
60 
0 " 
80 
1. 000 
1.045 
1.058 
1. 01 5 
0.995 
40 
100 " 
0 " 
1. 000 
1.059 
1,124 
1. 112 
1. 141 
40 
80 
20 
1. 000 
1.029 
1.058 
1.046 
40 
60 
40 
1. 000 
1-033 
1.027 
0.948 
0.915 
40 
40 
60 
1. 000 
1-055 
1.083 
1.058 
1.052 
40 
20 " 
80 
1. 000 
1.048 
1.043 
0.988 
0.964 
40 
0 " 
iOO " 
1. 000 
1.042 
1.058 
1.036 
I.0I5 
20 " 
120 " 
0 " 
1. 000 
1.062 
1.098 
1.084 
1.093 
20 " 
100 " 
20 " 
1. 000 
1.054 
1.058 
1.003 
0.983 
20 " 
80 
40 
1. 000 
1.069 
1.088 
1.043 
1.037 
20 " 
60 
60 
1. 000 
1.083 
1. 141 
1. 147 
1. 169 
20 " 
40 
80 
1. 000 
1. 014 
1.003 
0.921 
0.889 
20 " 
20 " 
100 " 
1. 000 
1.022 
1.030 
0.963 
0.939 
20 " 
0 " 
120 " 
1. 000 
I.OI8 
1,018 
0.982 
0.969 
0 " 
140 " 
0 " 
1. 000 
1.027 
0.980 
0.919 
0.875 
0 " 
120 " 
20 " 
1. 000 
I.0I9 
1.007 
0.949 
0.916 
0 . " 
100 " 
40 
1. 000 
1.007 
0.996 
0.930 
0.890 
0 " 
80 
60 
1. 000 
1.040 
0.996 
0.920 
0.880 
0 " 
60 
80 
1. 000 
1. 03 1 
I.OOI 
0.948 
0.910 
0 " 
40 
100 " 
1. 000 
1.054 
1.039 
0.982 
0.954 
0 " 
20 " 
120 " 
1. 000 
1.030 
1.039 
1. 000 
0.986 
0 " 
0 " 
140 
1. 000 
1. 017 
1.036 
1.025 
0.998 
potassium phosphate was treated as though it were a salt of a univalent 
acid, on account of the fact that it dissociates for the most part in K+ 
and H2P04~ ions. The 36 solutions provided all the possible combina- 
