(3) Calcium Arsenate. 

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

 ing form of guaranty : — 



Per Cent. 



Active ingredients: — 



Tricalcium arsenate, not less than . . . . . . .76.00 



Total arsenic pentoxide, not less than . . . . 42 . 50 



Total arsenic {as metallic) , not less than . . . . 28.00 



Inert ingredients, not more than . . . . . . . .24.00 



Water Soluble. 



Soluble arsenic pentoxide, not more than 

 Soluble arsenic (as metallic) , not more than 



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 

 fiocculent character insuring a fair power of suspension and imiform dis- 

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

 persistent under average weather conditions. 



Standakd 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. Naturally 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. 



