February, *18] 
LOVETT: CALCIUM ARSENATES 
61 
3. The addition of lime or of lime-sulphur materially reduced the 
burn and usually prevented serious burn entirely. 
4. The addition of lime-sulphur did not afford as perfect protection 
from burn as did the lime. 
It is a matter of common observation that lime-sulphur used in mid¬ 
season, even at a very high dilution on foliage which has not been 
sprayed previously that season with lime-sulphur, will sometimes give a 
serious burn. Likewise scab areas are found to afford a ready spot 
for the beginning of spray burn and in our tests it was evident that 
spray injury was most usual at such points and spread in all directions 
from the edges of the scab area. Another factor which appeared to be 
of equal importance in determining the probability and seriousness of 
the burn with a questionable spray was the natural vigor of the tree. 
Vigorous trees with large dark leaves seemed much more resistant to 
burn. Or to state it another way, materials which gave a considerable 
burn on average trees and on those showing more or less scab infection, 
in many cases showed no injurious effects when applied to vigorous 
clean foliaged trees. 
Summary 
1. The pure calcium salts, CaHAs0 4 and Ca 3 (As0 4 ) 2 , have been 
prepared; and the properties essential for use as a spray material 
tested. 
2. Acid calcium arsenate was found to be more soluble and less 
stable when subjected to unfavorable conditions than was the neutral 
calcium arsenate. 
3. Either of the pure salts or the commercial salts when in solution 
with an excess of CaO or with lime-sulphur gave no unfavorable reac¬ 
tion and judging from a chemical laboratory test should prove safe 
spray materials. 
4. Care should be observed to ascertain that the lime used is fairly 
pure CaO and not CaC0 3 . 
5. Preliminary field tests would indicate that a sufficient additional 
guarantee against burn is secured as to warrant the addition of an 
excess of CaO in the lime-sulphur-calcium arsenate application. 
6. In preparing the solution for field spraying the lime should be 
slaked and added to the water in proper proportions in the spray tank 
and the solution agitated vigorously for 15 minutes or more before 
the calcium arsenate is added. 
Literature Cited 
1. Sanders, G. E. 1916. Arsenate of Lead vs. Arsenate of Lime. Proc. Ent. Soc- 
Nova Scotia, 1916. No. 2, p. 40. 
2. Scott, W. M. 1915. Arsenate of Lime or Calcium Arsenate. Jour. Econ. 
Ent., VIII, No. 2, p. 194. 
