65 



(see our Bui. io6) , or be due to reactions between the lime-sulphur 

 solution and the arsenical, making the latter soluble. Lime sulphur 

 solutions containing any material quantities of soda or potash are 

 especially dangerous in the latter respect. ( See our article on Peach 

 Sprayiing in 191 1 Report of State Hort. Assoc.). 



We have wholly prevented the latter action on peaches during 

 the past summer, either by using lead ortho-arsenate, Pb3 (ASO4) 

 2, with the lime-sulphur solutions, or by precipitating the sulphur 

 from solution with iron sulphate before adding the ordinary arsen- 

 icals. The former method is preferable, which indicates the desir- 

 ability of manufacturing the ortho-arsenate here in the East as well 

 as in California. 



It also is probable that the ordinary mixed lead arsenates can 

 be safely used with lime-sulphur solution by adding to them some 

 free lead, preferably in the form of lead acetate or "sugar of lead," 

 before combining them with the solution. The amount of the lat- 

 ter actually required depends on the percentage of soluble arsenic 

 and of acid arsenates present in the commercial lead-arsenate sam- 

 ple and also on the amount of free lead already present. In gen- 

 eral, however, one-fourth to one-third of a pound of "sugar of lead" 

 should be sufficient to render safe the two pounds of ordinary lead- 

 arsenate paste. 



ADVANTAGE'S OF SpRAYING. 



(Large Pile Perfect.) 



