242 ReEPoRT ON Crop PRODUCTION OF THE 
Calcium carbonate was added in a quantity entirely sufficient 
to neutralize any possible acidity which might arise from the 
use, by the plants, of bases in excess of the use of acids from 
the various salts. This caused the reversion of the acid phos- 
phate, of course, but did not thereby render the phosphorie acid 
unavailable. 
In part of the experiments of 1899-1900 the ammonium nitrate 
was replaced by calcium nitrate. The various salts used were 
supposed to be chemically pure. It was discovered, when too 
late, that some of those used in 1898-1899 were not strictly free 
from potassium, and for that reason in the first year’s experi- 
ments all of the first four boxes in the series received more or 
less potassium outside of that derived from the water and sand. 
In the second year’s work the chemicals are regarded as having 
been strictly free from potassium, 
It is not at all certain that the compounds used to feed these 
plants were the best in kind and proportion that could have been 
selected for promoting thriftiness of growth. Unquestionably 
the plants did not thrive as they would under usual forcing 
house conditions, but whether this was due to the peculiar 
character of the soil or to a lack of adaptation on the part of the 
food supply is not known. Probably both factors exerted an 
influence. 
The water.—The water used in these experiments was distilled. 
It was not entirely pure, however. In the second year’s work 
(1899-1900) the water was taken to the forcing house in twelve 
large lots and the percentage of potash was determined in each 
lot. The quantity of potash present was found to vary from 
.0608 to .0074 gram in ten liters of water, averaging .002 gram. 
As the amount of water applied per can did not exceed eighteen 
liters in any case, the potash derived from the water per can 
was not over .0036 gram. The water was applied according to 
the judgment of the one in charge of the forcing house. 
