EXPERIMENTAL STUDY. 47 
making the proportion of CaO as sulphate to MgO as carbonate as 
follows: + to 5,4 to 6, 4 to 7,4 to 8, and 4 to 9, respectively, or, count- 
ing the calcium carbonate previously added, CaO to MgO as 9 to 5, 
8 to 6, 7 to 7, 6 to 8,and 5 to 9. In the pots oats were replanted, and 
in the course of nine days were uniformly sprouted in each pot. They 
continued to grow, were of good color, thrifty, and were free from 
shriveling of the root system, as was the case before the calcium sul- 
phate was added. These plants were brought to maturity, producing 
seed. (See Pl. I.) The growth in the five pots appeared to be 
normal except in the last, containing a total of CaO 0.5 per cent, or 
as sulphate 0.4,and MgO 0.9 per cent. Here, while there was a mod- 
erate development of the plant, it did not show the thrifty condition 
of the other plants in the soils containing more lime, indicating that 
there was not enough calcium in soluble form to wholly counteract 
the injurious effects of the magnesia. 
While the plants in the pots to which calcium sulphate had been 
added were growing, the pots containing the carbonates were replanted 
from time to time. The injurious results were continuous during the 
several months, the calcium carbonate not being able during a period 
of that length to counteract the effect of the excess of magnesia. 
LIME AND MAGNESIUM AS NITRATES IN SAND CULTURES. 
In order to test the two bases, calcium and magnesium, in a more 
soluble form, sand cultures were made in which these two elements 
were applied in the form of nitrates. These series of cultures were 
made to test the relation of the two bases to each other, and to find 
that ratio between the two that offered the best conditions for the 
growth of plants. 
There was added to 30 kilograms of pure white sterilized sand the 
following: 
Per cent. 
a hE I A pg A a 0.1 
ermramnnnee 2 rE 0.1 
UNIS beeen 2s eo a so ot ad oe 
TE aS ee ee eee oe 0.1 
2a ete ee ee ee ee eta Trace. 
These salts were finely powdered, mixed with a small quantity of 
sand, and then with the whole. The sand was put into sixteen pots, 
in two series of eight each, and calcium and magnesium nitrates added 
in solution in such proportion as to correspond to the following ratios: 
To 2 A pots, MgO, 0.8 per cent; CaO, 0.1 per cent. 
B pots, MgO, 0.7 per cent; CaO, 0.2 per cent. 
C pots, MgO, 0.6 per cent; CaO, 0.3 per cent. 
D pots, MgO, 0.5 per cent; CaO, 0.4 per cent. 
E pots, MgO, 0.4 per cent; CaO, 0.5 per cent. 
F pots, MgO, 0.3 per cent; CaO, 0.6 per cent. 
G pots, MgO, 0.2 per cent; CaO, 0.7 per cent. 
H pots, MgO, 0.1 per cent; CaO, 0.8 per cent. 
