52 
IT. C. Experiment Station 
to withstand the temperature of 95° for 12 hours is found in the amount of 
water contained by the seed when this is expressed as a ratio or as a per¬ 
centage of the oven dry weight - of the seeds. The oven dry weight of the 
seeds furnishes a nonvariable base for computation of the ratios or per¬ 
centages expressing the moisture content. Without exception, when the 
moisture content after the preliminary drying was as great as 3.9 per cent 
of the oven dry weight, the viability of the seeds was seriously impaired by 
heating at 95° for 12 hours. 
When the moisture content after the preliminary drying was not greater 
than 3.62 per cent of the dry weight of the seeds, no serious loss of viability 
resulted from the subsequent treatment at 95°. Furthermore, when the 
water content after drying was not greater than 3.19 per cent of their dry 
weight, the seeds heated at 95° for 12 hours germinated more promptly 
than the untreated seeds used for a check. The statement that, when the 
moisture content of cotton seed is not greater than 3.19 per cent of their 
dry weight, the seed may be safely subjected to a temperature of 95° 
for 12 hours without consequent loss of vaibility may then be considered 
to apply to any lot of normal cotton seed. 
In the course of these studies certain other experiments were performed 
which further show the relation of time and temperature as factors in¬ 
fluencing the water content of seeds during desiccation. In one of these 
experiments, cotton seeds were desiccated in a gas oven at a temperature 
of about 45° C., and at intervals of 24 hours the seeds were cooled in a 
desiccator, carefully weighed in order to determine loss of water and re¬ 
turned again to the oven. At the end of 144 hours, the temperature was 
raised to 60° C. and weighings were again made at the end of 24 and 48 
hours. In another test seeds being dried at 60° C. in an electric oven 
were weighed at frequent intervals until their weight became practically 
constant. The temperature was then raised to 70° C. and the seeds were 
weighed after periods of 24, 48, 72, and 96 hours, and finally heated at 
103° C. in order to determine their total water content. The results of 
these tests were presented in Table IV. 
In experiment 7 the water content of the seeds rapidly diminished during 
the first 24 hour period of drying and continued to decrease markedly, 
but less rapidly, during the second and third periods. By the end of 72 hours, 
the weight of the seeds had became practically constant, only insignificant 
amounts of water, cumulatively less than 0.5 per cent, being lost during the 
three succeeding 24-hour intervals. When at the end of 144 hours the tempera¬ 
ture was raised to 60° C., a marked reduction of water content of the seeds 
again occurred by the end of 24 hours. Little water was lost during the second 
24-hour period of heating at 60°. By this time, the weight of the seeds and 
their water content had become nearly constant for the temperature of 60° C. 
