April, ’23] 
SPEADERS AND SPRAYING, DISCUSSION 
205 
Mr. G. E. Sanders: I would like to ask whether increased burning 
results from calcium caseinate in combination with straight arsenate of 
lead. 
Mr. R. H. Smith : That has never occurred in actual orchard spraying. 
The charts that Mr. Stearns showed indicate that calcium caseinate 
decreased burning. We have run 46 samples and in each case the cal¬ 
cium caseinate decreased burning. 
Mr. G. E. Sanders: That is arsenate of lead combined only with 
calcium caseinate ? 
Mr. R. H. Smith: Yes. 
Mr. B. A. Porter: We have used plain arsenate of lead with calcium 
caseinate in Connecticut and there was no burning. 
Mr. W. P. Flint: The difference was only 1 or 2 per cent in Illinois 
and in some cases the percentage of worms in the lot sprayed where the 
spreader was used, was greater than where it was not used. 
Mr. G. E. Sanders : I want to say that from an analytical standpoint 
the relation of calcium caseinate to lead arsenate should give increased 
burning; because when we had Mr. Kelsall at the laboratory we did 
careful work on the addition of varying quantities of lime to lead arsenate 
and where he used less than ten per cent by weight of lime with lead 
arsenate he increased the amount of soluble arsenic greatly, and where 
the amount of lime was more than ten per cent, there was a decrease in 
the amount of soluble arsenic; so that with the small amount of lime 
that there is in calcium arsenate, I would expect to get quite an in¬ 
crease in the amount of burning. 
Mr. William Moore: I would like to say a word about the reactions 
of lime and lead arsenate and calcium caseinate and lead arsenate, and 
what we define as soluble arsenic and arsenic that will cause burning. 
It is true that if you add lime to lead arsenate that the amount of 
soluble arsenate increases. It has also been demontsrated, I believe, for 
a number of years, that the use of lime with lead arsenate will usually re¬ 
duce burning. When lead arsenate is in contact with water, a reaction 
occurs which produces a certain amount of soluble arsenic, which soluble 
arsenic is in the form of arsenic acid. When you add lime it is no longer 
arsenic acid, but calcium arsenate. 
Now the solubility of the arsenic compounds present in solution may 
have a bearing on the degree of burning. In other words, you can have 
two solutions with identically the same amount of soluble arsenic, one in 
the form of calcium arsenate and the other in the form of arsenic acid. 
These two solutions may give entirely different results on foliage. An 
