604 Philippine Journal of Science 1920 
from set to set, by increments of 0.1 of the total salt content 
of the mixture, which was osmotically the same in all the sets. 
For these tests rice was employed, growing in a water-saturated 
soil, in culture vessels having a capacity of approximately 19 
liters each. The present experiments are of a preliminary na- 
ture; but no previously reported work has dealt with the range 
of possible sets of proportions in the way here followed, and 
the results may be valuable to other workers. The study was 
carried out at the College of Agriculture, at Los Bafios, during 
the period from June to October, 1918, which comprises the 
most favorable season for the growth of rice in this part of 
the Philippine Islands. It is a pleasure to acknowledge in- 
debtedness to Prof. B. E. Livingston, of Johns Hopkins Univer- 
sity, for aid in the preparation of this paper; and to P. David 
and F. de Peralta for assistance in the experimentation. 
The rice plants were grown to maturity. The total osmotic 
value of the salts added to the soil was always calculated to be 
the same, the unit of variation being 0.1 of this calculated value. 
This method is similar to that already employed in solution cul- 
tures and in sand cultures by various workers.' In the present 
experiments with water-saturated soil the salts were supplied 
in addition to those already present in the soil. To each culture 
a sufficient quantity of salts was added to give in 19 liters ot 
water a total osmotic concentration of approximately 0.5 atmos- 
phere at 25° C.? 
It is of course realized that, after addition to the soil, the salts 
were immediately altered to a greater or less degree by chemical 
changes and absorption. But so little is known concerning such 
alterations that they cannot be quantitatively discussed as yet. 
The thirty-six different salt combinations may be represented 
by means of a triangular diagram like that described by Shive 
in the papers already cited. Such a diagram is shown in fig. 1. 
In this triangular diagram each of the intersections of lines 
represents one of the salt combinations used. The lowest row 
"See the articles by Tottingham,(15) by Shive,(13,14) and McCall(10) 
that are cited at the end of this paper. : 
“The culture medium was composed of approximately 19 liters of 
water-saturated soil. It contained approximately 16,000 grams of mols- 
ture-free soil and 12,000 cubic centimeters of solution. The quantity 
of salt added to each culture was calculated to give approximately 
0.5 atmosphere osmotic concentration in 19 liters of solution; this woU 
give approximately 0.79 atmosphere in 12,000 cubic centimeters. 
