118 
If the arsenites are to be applied in the old way, without the addition 
of lime or Bordeaux mixture, we must conclude, from all the evidence 
at hand, that Paris green is our most valuable arsenite for insecticidal 
purposes. About the only objections that can be raised to it are its 
higher price and its greater specific gravity than London purple. 
LONDON PURPLE. 
London purple is an arsenite of lime with impurities, principally col- 
oring matter. Or, according to the analyses of Mr. H. Snyder, as pub- 
lished in Bulletin 18, p. 36, of the Cornell Experiment Station, London 
purple contains three calcium arsenites Ca 3 (As0 3 ) 2 , Ca(As0 2 ) 2 , and 
Ca 2 (As 2 5 ). amounting to about 72^ per cent of the entire weight of 
the commercial article. The impurities as given by the same authority 
are 23.04 per cent coloring matter, small amounts of Fe 2 3 , A1 2 3 , 
S0 3 , and water. 
The total solubility of this arsenite in water Mr. Snyder found to be 
52.38 per cent. The fact that so large a portion of London purple is 
quickly soluble in water accounts for the serious injuries that it often 
does to foliage. But as we are able by the addition of lime or Bordeaux 
mixture to prevent these injuries, it must be ranked, on account of its 
cheapness and the readiness with which it remains in suspension in 
water, as second to none of the arsenites as an insecticide unless it be 
found true that it is less effectual in destroying insects. 
OTHER ARSENITES. 
A few other arsenites deserve passing mention because of their hav- 
ing been used for the destruction of insects rather than because of any 
great value that has yet been attached to them for insecticidal pur- 
poses. 
ARSENITE OF AMMONIA. 
In the report of the Entomologist of the IT. S. Department of 
Agriculture for 1889 (p. 357), is printed a statement from the pen of 
Miss Mary E. Murtfeldt, saying she found arsenite of ammonia more 
injurious to foliage than arsenic in a watery solution, and in Bulletin 
23 (p. 55) of the Division of Entomology, Miss Murtfeldt reports the 
same solution destructive both to leaf-feeding insects and to foliage. 
In the report of the Entomologist of the Department of Agriculture for 
1890 (p. 264) Mr. Osborn, of Iowa, reports upon experiments with this 
substance and says he found it as effectual as London purple or Paris 
green for the destruction of insects and not injurious to foliage. 
ARSENITE OF POTASH. 
This arsenite, which is soluble in water, was reported by Mr. E. W. 
Jones in Bulletin 1, Division of Entomology (p. 51), as effectual in 
destroying Boll Worms on cotton. Of its effects on foliage nothing is 
said. 
