176 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
Another series of trials with the extract obtained by repercolation 
was carried on by Mr. Schwarz, at Selma, Ala., in 1880. He reports as 
follows : 
The extract I used was prepared "by Messrs. Wilkjns & Brooks, druggists, at Selma, 
from imported insect-powder, by the repercolation process as prescribed in the Ameri- 
can Pharmacopoeia. From 1 pound of the powder 1 pint of extract was obtained, 
1 drop of the extract thus representing I grain of the powder. The extract is a 
dark-brown fluid, with but a very small amount of sediment, which is very easily 
shaken up and does not interfere in the least with applying the fluid through very 
small orihces. The actual cost of preparing the extract was 50 cents. The residuum 
of the powder from which the extract was made was tried several weeks afier wards 
and did not seem to have lost much of its strength, as upon application with the in- 
sect-gun a number of pea-weevils, Which were just at hand, were immediately affected. 
It is thus quite possible that another pint of extract of the same strength as the first 
could have been obtained from the same pound of powder. This must be taken in 
account in the results obtained by my experiments. The extract was diluted with 
water, and by a series of trials I found that 10 drams of the extract to 2 gallons of 
water, when applied with the fountain-pump or atomizer, is sufficient to kill the 
average-sized worms which come in contact with the fluid. Full-grown worms mostly 
recover, while very young worms are fatally affected by a moderate application of a 
mixture of 4 drams of the extract to 2 gallons of water. 
The mixture of 10 drams of extract to 2 gallons of water was applied by means of 
the fountain-pump from above as well as from the side. There were plenty of worms 
mostly below average size on the plants. In the application from above, i. e., imi- 
tating the common sprinkling arrangements, the liquid was very liberally used, the 
upper side of the leaves being entirely wet. Very many worms were affected and 
killed by the liquid, but a large proportion were not reached by the spray, and the 
application did not protect the plants, for they were denuded of leaves in the same 
time as those not experimented with. The same mixture was applied from the side 
with the fountain-pump, the liquid being also used freely at a rate which I estimated 
at from 60 to 70 gallons per acre, great care being taken to apply the liquid to every 
part of the plants. Upon examination about 14 hours afterwards only a few large 
worms were found on the plants, all the others being dead or dying. Numerous trials 
proved that the same mixture, when applied in the mist-like spray of a parlor-ato- 
mizer, is fully sufficient to kill the worms, the amount of the liquid necessary being- 
very small. A mixture of 8 drams of the extract to 2 gallons of water was thoroughly 
applied to a number of plants by means of the fountain-pump. All worms on the 
plants were affected within the usual time, but 16 hours afterwards a considerable 
portion of the larger worms had recovered, and were again feeding. My experiments 
would thus show that 1 pint of the extract (which is equal to 1 pound of powder) 
could only be diluted with about 26 gallons of water, or barely sufficient to go over 
one acre of cotton. This would be a rather unfavorable result, considering that to 
the cost of the powder that of making the extract has to be added ; but, as above 
stated, the extract I used was far from being a perfect one, or else better results 
would have been obtained. 
Although the results obtained by Professor Jones and Mr. Schwarz 
do not accord with each other — a divergence which is easily ex- 
plained, however, by the different extracts employed — they show suffi- 
ciently that the extract can be used more economically than the pow- 
der, a result which could not have been anticipated from the expiri- 
incuts made in 1879. Professor Jones estimates that 1 pound of powder 
converted into extract is sufficient to give 100 gallons of liquid, while 
