(S) Calcium Arsenate. 

 Form of Guaranty. — Calcium arsenate is usually sold under the follow- 

 ing form of guaranty: — 



Active ingredients: — 



Tricalcium arsenate, not less than . 

 Total arsenic pentoxide, not less than 

 Total arsenic {as metallic) , not less than 



Inert ingredients, not more than . 



42.50 

 28.00 



Water Soluble. 



Soluble arsenic pentoxide, not more than 

 Sohible arsenic {as metallic) , not more than 



Per Cent. 

 76.00 



24.00 

 100.00 



Per Cent. 

 1.50 

 1.00 



Because of the higher percentage of total arsenic contained in calcium 

 arsenate, it is evident that a smaller quantity of this material may be 

 used than of lead arsenate to obtain satisfactory results. 



Calcium arsenate is an effective poison, its fine particles and light 

 flocculent character insuring a fair power of suspension and uniform dis- 

 tribution. The white mixture indicates the leaf surface covered, and is 

 persistent under average weather conditions. 



Standard Formulas for Application. 

 There is a great difference in the rapidity of killing power between 

 arsenates and arsenites. For this reason the two classes of materials 

 cannot be compared on the basis of arsenic contained'. The following 

 table represents basic quantities of the several materials of standard or 

 near-standard composition which may be used. Naturallj^ the amounts 

 to be used must be varied to adapt the spray for use against various kinds 

 of insects and on different kinds of plants. 



