AZ 
been dissolved and precipitated, the dissolving of a new lot is com- 
menced, and in this way there is no delay in the preparation of the 
poison. 
The cost of arsenate of lead mixture at the figures given is brought 
down to $131.69 per ton, or about 635 cents per pound, exclusive of 
freight, labor, bags, etc. These latter factors should not increase the 
cost of the poison over one-half cent per pound, making the total cost 
of the arsenate of lead mixture in quantity about 7 cents per pound, 
against 125 to 15 cents per pound, the price conimonly charged for the 
dry mixture of the salts. 
For ordinary use in woodlands or in places not readily accessible, the 
150-gallon tanks have proved too cumbersome, and their use, with that 
of the heavy pumps which accompany them, has been abandoned. Our 
assistant director, Mr. E. C. Ware, has very satisfactorily demonstrated 
that much more and better work can be accomplished with a galvan- 
ized iron tank of about 25 gallons capacity, to which a Johnson pump 
has been attached. To prevent clogging, a strainer made of wire 
gauze, having 70 meshes to the inch, is attached to the base of the 
pump, while the flow pipe is removed and a hose coupling substituted. 
A Siamese connection is fastened to this coupling, thus enabling one to 
use two lines of hose. These tanks can be easily handled by two men, 
while the modified Johnson pump is of ample capacity for two lines of 
hose. 
One factor of considerable importance in extensive spraying opera- 
tions is the delay caused by the frequent clogging of the nozzles. In 
the tank I have mentioned the strainer at the base of the pump sifts 
out any foreign matter which may get into the tank, but even then the 
frequent coupling and uncoupling of the hose allows more or less rub- 
bish to find its way into the nozzle. To overcome this difficulty, our 
machinist, Mr. John Hancock, has prepared a nozzle involving the 
cyclone principle, but containing a wire-gauze strainer of the same 
mesh as the pump strainer. This strainer is cylindrical in form and is 
contained in the posterior part of the nozzle, while the cyclone heads 
are attached to the outer part of thenozzle. Our first Haneock nozzles 
contained but a single head. A few days of practical use in the field, 
however, suggested the advantage to be gained from increasing the 
number of heads, and the pattern finally decided upon bears one head 
at its extremity and three at equal distances around the side. With 
this nozzle a fine mistlike spray may be thrown in all directions to a 
distance of from 8 to 10 feet. 
To show the permanency of arsenate of lead when applied to the 
foliage in this manner, I have here samples of leaves sprayed June 1, 
1897, of which the poison is still in an effective’ condition. These 
leaves were taken at random from trees in the infested woodlands 
August 5, 1897. On these trees the caterpillars were dying as late as 
July 26. While we can not consider spraying with arsenate of lead to 
