December, '16] 



BUTCHER: FROZEN LEAD ARSENATES 



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feature of this experiment is that different commercial brands behave 

 differently under the same treatment. It is also interesting to note 

 that pure lead acid arsenate (sample 7) and pure lead basic arsenate 

 (sample 8) show no difference in settling properties after freezing. 



In order that some idea might be obtained as to the effect of freez- 

 ing on the adhesive properties of the arsenates an experiment was 

 conducted as follows: Strips of aluminum were cut so that each strip 

 measured exactly f x 2j inches, giving an area of 1.6875 square inches 

 for each strip. These strips were roughened, by dipping in strong 

 hydrochloric acid, in order that the arsenate solution might adhere 

 to better advantage. These strips were washed, dried, and weighed. 



Sample 1 was set aside for this experiment because it was representa- 

 tive of the type affected by freezing. Sample 3 was also chosen be- 

 cause its settling properties were not appreciably affected. This 

 sample was a stearated'- or water-proof arsenate of lead. Sample 6 

 was chosen because it represented that class whose settling properties 

 were not affected by freezing. In order that no errors be made two 

 strips were dipped into each sample while it was being agitated; these 

 strips were hung on fine copper wires and finally dried and weighed. 

 The results are given in Table I. 



Table T 



While the above experiment should not be considered as represent- 

 ing the possible deportment of frozen arsenates of lead under orchard 

 conditionSj nevertheless it would appear from these preliminary experi- 

 ments that the adhesive properties of certain arsenate pastes are af- 

 fected by freezing. 



^This type of arsenate is treated with a fatty material with the view of "water- 

 proofing" the dried spray in order that it will not be washed from the leaf by rain. 



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