280 Bovie: NoN-AVAILABLE WATER IN SOILS 
soil moisture. The air-dry quartz was weighed out, to the 1/10 
gram, in portions sufficient nearly to fill the tumblers. It was then 
spread over the bottom of a tray. The solution was added to the 
quartz in such a manner as to prevent, as far as possible, any un- 
even adsorption of the salts by the soil grains first wetted. After 
quickly mixing, the soil was dropped into the tumblers. When this 
quartz is carrying a 20 per cent. soil solution, it contains more 
than its optimum amount of water.* However, it was dropped 
into the tumblers in such a manner as to include air enough to 
supply the plants as long as it was necessary to grow them. By 
pounding the tumblers up and down on the table a few times, the 
inclosed air was worked out of the upper centimeter of the soil, 
which puddled, leaving a thin layer of free water on the upper 
surface. This also worked the air entrapped below the surface 
into quite large bubbles, the largest being about 5 mm. in diameter. 
The physical condition of the soil, thus obtained, appeared to be 
uniform throughout both series. 
Melted paraffin was poured over the surface of the quartz in 
each tumbler, five small holes were made through the cover thus 
formed, and then the wheat seeds, which had germinated in Zurich 
germinators until the radicles were from five to ten millimeters 
long, were dropped through the holes into the water layer on the 
surface of the soil. Five tumblers of each concentration were set 
up. 
The plants were grown in the glass house on a table in the center 
of the room, where they were under similar conditions, until they 
were ready to be wilted down. There was a marked difference, 
among the several concentrations, in the rate and amount of 
growth. With the exception of the 0.225 per cent. set, in which 
there was a stimulation, due undoubtedly to toxic effects, there 
was a regular decrease in both the rate and the amount of growth 
from the control set to that of the highest concentration. Plants 
that grew fastest used up their water first and were the first to 
wilt. 
When the water was nearly used up, as was determined by 
repeated weighings of the tumblers, the plants were put into a 
*It was necessary to use an excess of water so as to have enough to allow the 
plants to put on sufficient growth before wilting. 
