370 



STATE HORTICULTURAL SOCIETY. 



The following results were obtained by Mr. Snyder, formerly assistant 

 chemist at the experiment station: 



" In preparing the Bordeaux mixture the following reaction takes place: 



Cu S0 4 +Ca (OH) 2 =Ca S0 4 +Cu (OH) 2 . Both of these new products 

 are insoluble in water. If both the lime and sulphate of copper are 

 chemically pure, it would require 1 pound of lime to combine with 4 pounds 

 of copper sulphate (Cu S0 4 -f 8 H 2 0). A qualitative examination of the 

 filtered solution showed a small amount of copper hydrate (trace), calcium 

 sulphate, due to the extreme dilution of the solution, and calcium hydrate 

 due to the excess of lime used in making the mixture. The Bordeaux 

 mixture when ready for use has the following composition: 



Calcium hydrate in solution. 



Calcium sulphate in solution. 



Copper hydrate in solution (trace). 



Copper hydrate precipitated. 



Calcium sulphate precipitated." 



Since the hydrate of copper is the active principle of the Bordeaux 

 mixture, experiments were conducted to determine its value when applied 

 alone. 



No. 15. Hydrate of copper at the rate of ^ pound in 22 gallons of 

 water. 



Dates of 

 applica- 

 tions 



July 17. 



" 28. 

 Aug. 11 



" 21. 



Plants used. 



Apple (Alexander) . 



Pear (Howell) 



Quince (Champion) _ 



Peach (Downton) 



G rape ( Oriental) 



Egg-plant) 



Potato (Early Rose) 



Dates of observations and per cent, 

 of injury. 



July 23. Aug. 8. Aug. 22. Sept. 5 



It will be seen that the peach was the only plant injured; the leaves 

 appeared as if punctured, the holes being from jg to J inch in diameter. 



The hydrate of copper was also applied at the rate of \ and J pounds in 

 22 gallons of water. The results were the same as the above, except that 

 the peach showed less injury. 



No. 16. Hydrate of copper at the rate of ^ pound in 22 gallons of 

 water ; Paris green at the rate of 1 pound in 300 gallons of water. 



