40 
To obtain some definite information on this point two large pear 
trees were selected and half of one was sprayed with Bordeaux mix- 
ture containing 4 pounds of air-slaked lime and 6 pounds of copper sul- 
phate to 22 gallons of water. The other half was sprayed with Bor- 
deaux mixture containing 6 pounds of air-slaked lime and 6 pounds of 
copper sulphate to 22 gallons of water. The remaining tree was sprayed 
with a mixture made with 4 pounds of fresh lime, 6 pounds of sulphate 
of copper, and 22 gallons of water. In ten days the half of tree 1 sprayed 
with Bordeaux mixture containing only 4 pounds of air-slaked lime 
was seriously injured, the leaves and fruit being spotted and blistered 
like those in the experimental plats. The half of the tree sprayed with 
the mixture containing 6 pounds of air-slaked lime and the entire tree 
treated with Bordeaux mixture made with fresh lime showed no injury 
whatever. This shows the importance of always using fresh lime, as 
itis very difficult to determine the exact amount of air-slaked lime to 
use, owing to the varying quality of this substance. A simple method 
of testing the mixture for free copper is now frequently resorted to 
when we are in doubt as to whether enough lime has been added.* One- 
half ounce of ferrocyanide of potassium is dissolved in 2 or 3 ounces of 
water, placed in a bottle, and kept corked. When itis desired to test 
a fungicide for free copper a few drops of this solution is added. The 
least quantity of free copper immediately gives a brownish reaction. 
If there be no reaction when the ferrocyanide solution is added, it is 
safe to say that the solution tested contains practically no free copper. 
For the purpose of obtaining some definite information as regards 
injury to the foliage and fruit resulting from the treatments, all the 
trees were carefully examined. In considering this matter the burn- 
ing caused by the Bordeaux mixture is omitted, for the reason that, had 
this preparation been properly made, the damage would not have re- 
sulted. In Diagram 7 is shown graphically the results of the observa- 
tions made at this time. 
*First proposed by Dr. G. Patngeou in Prog. Agric. et Viticol. 
. 
