254 Report OF THE HortTiCcULTURAL DEPARTMENT OF THE 
nature. But as pointed out by Galloway and Gothe, and cor- 
roborated by a knowledge of the chemical composition of the mix- 
ture, this injury is owing to the use of air-slaked lime in its 
preparation. It is probable that the use of air-slaked lime not 
only causes injury from leaving a small amount of copper sulphate 
in solution, but from the formation of the basic sulphate of copper, 
which in itself is injurious.” 
In the light of more recent investigations, and of experiences 
in practice, it is very doubtful if either of the above workers would 
now lay much stress upon air slaked lime as a cause of the injury 
from bordeaux mixture. 
In a letter dated January 23, 1907, Bain kindly sends me the 
following as to the relation of lime and weather to injury from 
bordeaux mixture: “ You will recall that I found lime to be the 
sole constituent of the bordeaux mixture which retards its injurious 
action. Since that time I have found that liquid water in contact 
with hydrate of lime is necessary for its conversion into the car- 
bonate. In fact, I have bordeaux sprinkled on glass plates in my 
laboratory which have been in a dry atmosphere for about six 
years, and the lime still exists in the form of the hydrate. It is 
a well-known fact that the hydrate of lime is very much more 
soluble in meteoric water than the carbonate. I found that one 
night’s exposure to a good dew is sufficient to convert the hydrate 
into the carbonate. A rain falling within a short time upon the 
leaves sprayed with the bordeaux mixture will find the lime in 
its soluble hydrate condition and will wash off a greater per- 
centage of the lime present. Following rains or dews will thus 
cause much greater injury than would have occurred if a few dews 
had followed the spraying before the occurrence of the rain. It 
is probable that this fact will influence but slightly the practical 
control of injury to foliage, though it explains in many instances 
the injury, which I have hitherto been unable to comprehend.” 
- INVESTIGATION IN REGARD TO BORDEAUX INJURY 
AT THE NEW YORK AGRICULTURAL EXPERIMENT 
me eal CIN 
It was the unusual severity of bordeaux injury in 1905 that 
caused this Station to begin a study of the trouble. There was 
a greater loss of fruit and more damage done to apple foliage 
in New York in I905 than in any preceding year in the history - 
of spraying. True, there had been other years in which the losses 
