MISCELLANEOUS INSECTICIDE INVESTIGATIONS. 39 



With lime-sulphur. — Triplumbic arsenate of lead, combined with 

 lime-sulphur solution again proved to have a slower toxic effect than 

 either di or di and tri arsenates so combined. The triplumbic com- 

 mercial No. 1 arsenate of lead was again less rapid as a poisoning 

 agent than the commercial products of diplumbic compositions. It 

 was found that the mixing of lime-sulphur and arsenate of lead results 

 in a smaller consumption of foliage than when arsenate of lead is used 

 alone. 



FIELD TESTS WITH APPLES. 



With lime-sulphur. — Arsenate of lead consistently proved to be the 

 most effective poison tested during the three years of experimentation, 

 Triplumbic arsenate with lime-sulphur did not hold the codling moth 

 in check quite as well as the ordinary commercial (diplumbic) arsenate 

 of lead. Powdered arsenate of lead is equally as effective as the paste 

 form for the control of the codling moth. 



LABORATORY AND FIELD TESTS. 



With commercial sodium sulphid No. 1. — The value of arsenate of 

 lead is not decreased when combined with sodium sulphid ; in fact 

 the sodium arsenate formed is more active as a toxin than lead 

 arsenate. However, field experiments with apples show that this 

 combination is impracticable, owing to the frequency of foliage injury 

 due to the formation of the soluble sodium arsenate. 



With commercial barium tetrasulphid. — Arsenate of lead mixed 

 with barium tetrasulphid was used with satisfactory results for the 

 control of the codling moth. This combination was found safe for 

 use on apple foliage. 



With nicotine solutions and lime-sulphur. — Arsenate of lead may be 

 mixed with nicotine solutions and lime-sulphur for the control of 

 certain apple sucking and chewing insects, as well as fungous dis- 

 eases. The mixing of these materials does not lessen their individual 

 value and moreover may be applied to apple foliage with safety. 



With Icerosene emulsion and lime-sulphur. — The combination of 

 lead arsenate, kerosene emulsion, and lime-sulphur should not be 

 used as an orchard spray, owing to the breaking down of the materials 

 and the subsequent foliage injury. 



With fish-oil soap and lime-sulphur. — The combination of arsenate 

 of lead, fish-oil soap, and Hme-sulphur is not a compatible mixture 

 for spraying purposes, since an insoluble calcium soap is formed. 

 In our experience, any combination containing lime-sulphur and soap 

 should not be used. 



ARSENATE OF CALCIUM. 



An effort was made to secure a satisfactory substitute for arsenate 

 of lead, a compound which would be as efficient and at the same time 

 less costly. With this object in view arsenate of calcium was used 



