34 FIRST ANNUAL REPORT OP THE STATE ENTOMOLOGIST. 



immature a stage or in such condition that it will not permanently 

 retain the poison. 



2. London Furple as an Insecticide, 



An analysis of a specimen of London purple by the chemist of the 

 U. S. Department of Agriculture gave the following results:* 



Per cent. 



Rose aniline » 12.46 



Arsenic acid 43. 65 



Lime 21.82 



Insoluble residue , 14.57 



Iron oxide 1.16 



Water 2.27 



Loss 4.07 



300.00 



As appears from the above analysis, it is mainly an arseniateof lime. 

 It is a refuse material, obtained in the manufacture of analine dyes, 

 heretofore worthless. Its cost, therefore, need not much exceed that 

 of package and transportation. Its efficacy in the destruction of in- 

 sects appears to be about equal to that of Paris green, although it does 

 not accomplish its work so rapidly, for often its effects are not appa- 

 rent until the second or third day after its application. From the 

 short time that experiments have been made with it, we are not pre- 

 pared to say that it may entirely take the place of Paris green, yet 

 there are several considerations which seem to give it a greater value as 

 an insecticide than that substance. 



Its cost is much less, as it can be purchased at fifteen cents a pound, 

 and at ten cents or less by the keg or barrel. Less than half the quan- 

 tity is needed. Prof. Riley states that while the cost to the cotton 

 planter of the Paris green material per acre has been one dollar, that 

 of the purple will not exceed five cents. 



It is of nearly uniform strength, as its production being much in 

 excess of demand, it does not pay the manufacturer to adulterate it 

 by mixture with any other substance. 



As mixed for use it is far less poisonous than Paris green, as is 

 shown from its having been eaten by persons without serious harm.f 



It is more adhesive to vegetation and, therefore, not as readily 

 washed away by rains. 



* Annual Report of the Commissinner of Agriculture for the Year 1878, p. 144. 



t" I know of two negroes who stole some flour in which it had been mixed in the or- 

 dinary proportion for use on cotton, and made biscuits thereof. Both were made sick, 

 but neither seriouslj. (Prof. Riley in American, Entomologist, iii, 1880, p. 246.) 



