16 DireEctTor’s REPORT OF THE 
in such a way as to take it out of the general solution. When 
there was present an excess above the requirements of these two 
components of the milk the germicidal action of the chloroform 
was prompt and satisfactory. 
DEPARTMENT OF BOTANY. 
Potato spraying experiments.— During the season of 1906 the 
potato spraying experiments begun in 1902 were continued along 
practically the same lines as in previous years. In the ten-year 
experiment at Geneva five sprayings increased the yield 63 bushels 
per acre, while three sprayings increased it 31.75 bushels. In the 
duplicate of this experiment at Riverhead, Long Island, the gain 
due to five sprayings was 53.25 bushels per acre and to three 
sprayings 21.5 bushels. In fifteen farmers’ business experiments, 
including 225.6 acres, the average gain due to spraying was 42.6 
bushels per acre; the average total cost of spraying $5.18 per 
acre; and the average net profit, $13.89 per acre. Sixty-two 
volunteer experimenters, spraying 598 acres, reported gains aver- 
aging 44.5 bushels per acre. 
One-half the time during which this series of experiments is 
expected to run has now passed. Thus far the results are highly 
favorable to the practice of spraying. In the ten-year experi- 
ments at Geneva, the average gain for five years from spraying 
every two weeks has been 132 bushels to the acre, and from 
spraying three times during the season 103.3 bushels; at River- 
head the corresponding gains have been less, but still decided, 
being 66.3 bushels and 35.3 bushels respectively. 
In forty-eight business experiments made in four years the 
average gain due to spraying has been 52 bushels to the acre, the 
average total expense of spraying, $4.85 per acre, and the average 
net profit from spraying $20.51 per acre. In 153 volunteer experi- 
ments reported in three years the average gain from spraying 
was 58 bushels to, the acre. 
DEPARTMENT OF CHEMISTRY. 
Effect. of treating milk with carbon dioxide under pressure. In 
connection with some work done in making kumiss from cows’ 
milk, it was learned that carbon dioxide gas under pressure has 
the power of delaying the souring of milk. The suggestion thus 
obtained was utilized in studying the effect of treating milk with 
carbon dioxide under pressure, the milk being carbonated in 
