121 
ARSENITES WITH KEROSENE EMULSION. 
Agents of the Division of Entomology* and others! have experi- 
mented with the arsenites in kerosene emulsion for the destruction of 
haustellate and mandibulate insects with one application, but the com- 
bination has, so far, proved a failure. 
In such a mixture the arsenite will separate in buttery clots and rise 
to the surface or cling to the inside of the vessel, and the separation of 
the oil from the emulsion is also hastened. 
There seems to be no reason why the arsenites could not be used 
with pyrethrum. 
THE ARSENITES AS EXTERNAL IRRITANTS. 
The arsenites are usually thought of as only being destructive to 
insect life when taken internally. 
In the report of the Michigan board of agriculture for 1888 Mr. L.. 
H. Bailey, of South Haven, Mich., is reported as saying he had been 
entirely successful in ridding horses of ticks and cattle of " black lice" 
with a single application of London purple in water. 
Mr. H. Garman (in Bui. 21 of the Kentucky Exp. Sta.) says he has 
found London purple more destructive than pyrethrum when applied- 
to plant-lice. 
In the Eeport of the Entomologist of the U. S. Department of Agri- 
culture, 1890 (p. 142), Mr. D. W. Coquillett reports success in destroy- 
ing scale-insects with arsenic, in combination with each of the following, 
mixtures : 
Muriatic acid, mercury and quick lime. 
Muriatic acid, zinc and quick lime. 
Muriatic acid and zinc. 
Muriatic and nitric acids, mercury and quick lime. 
Muriatic and nitric acids and copper. 
Muriatic and nitric acids and zinc. 
And in the Eeport of the Entomologist of the U. S. Department of 
Agriculture, 1886 (p. 557), Mr. Coquillett reports having used the 
arsenites successfully in the proportions of 1 pound to 4 gallons, 1 
pound to 6 gallons, and 1 pound to 8 gallons of water for the destruc- 
tion of scale-insects. So the arsenites should not be considered poisons 
that kill only when taken internally. They are of some, perhaps much r 
importance as external irritants also. 
In the discussion Dr. Beal suggested that it might be desirable to 
regulate the amount of arsenic in Paris green by law. 
Mr. Weed thought London purple more constant in the amount of 
arsenic it contained than Paris green, but Mr. Gillette believed the re- 
verse to be true, and thought the general testimony was to this effect. 
^Rep. of Ent. U. S. Dept. of Agr., 1886, p. 557. 
tBul, 10, Iowa Exp. Sta., p. 414, 
