i6 Influence of Arscnic in Solls [Oct, 



There is nothing in these results to indicate that arsenic trisulfide, 

 or zinc arsenite, is as safe as lead arsenate for use as an insecticide. 

 Arsenic trisulfide may be safer when first added to the soil. as is 

 shown by its being almost insoluble when first applied and having 

 practically no toxic influence upon ammonification; but, as bacterial 

 action takes place in the soil, the arsenic of the arsenic trisulfide is 

 much more soluble than that of lead arsenate, and becomes toxic 

 to the nitrifying organisms when it is present in large quantities. 



