REPORT OF THE SOCIETY 77 



I have used various grades of white arsenic on potatoes in Nova Scotia 

 and the burning there from 99 per cent pure material was usually moderate 

 to bad, say from 10 to 30 per cent of the leaf area destroyed. With dust collector 

 arsenic, much finer material and only 90 to 96 percent pure, the burning was 

 invariable severe. The addition of lime, particularly magnesium lime, greatly 

 increased the burning. 



I do not think that we can ever recommend generally even the most pure 

 white arsenic for use straight on potatoes. It may be that some particular grade 

 from certain ores may find a place in the drier sections of the northwest, but 

 there I am quite sure that the source, the purity and the methods of refining 

 would have to be watched too carefully to make it of safe, wide application. 



2. In Baits. 



For cutworm and grasshopper baits, white arsenic is ideal. Some years 

 ago, J. J. Davis reported excellent results from a low grade white arsenic from 

 one of the Western U. S. Smelters. In 1921, I corroborated Davis' work, using 

 dust collector arsenic of much greater fineness than Davis had used. I found 

 that one pound of dust collector arsenic, running 92 percent pure and of a fire- 

 ness of 250 to 300 meshes to the inch, possessed greater killing value on grass" 

 hoppers than an equal weight of 99 percent pure material having a fineness of 

 around 200 meshes. The higher solubility of the dust collector arsenic on ac- 

 count of the impurities in it and its greater fineness were both factors in causing 

 it to be superior pound for pound to the purer material. I found dust collector 

 white arsenic superior to all other materials tested for grasshopper baits. It is, 

 of course, lower in cost than pure white arsenic and infinitely cheaper than 

 Paris green. 



We found the best and most economical bait formula to be: 



5 lbs. dust collector arsenic. 

 10 lbs. salt. 

 100 lbs. bran. 

 Water to make a mash. 



We could get no benefit from banana oil, fruits, fruit extracts or any other 

 attractants. The great attractant in the locality in which I was experimenting, 

 Manitoba, was watei . Farther west, where the water was alkaline, Mr. Kelsall 

 carried on numerous experiments in 1921 and there he got no appreciable benefit 

 from salt. In Manitoba, where the water was sweet, I got a decided benefit 

 from salt. 



Paris green is, of course, a good poison in baits, but it causes more poisoning 

 than white arsenic among the men in the mixing stations and is much more 

 expensive. 



