176 REPORT 



Another series of trials with the extract obtained bj^ repercolation 

 was carried on by Mr. Schwarz, at Selma, Ala., in 1880. He rei)orts as 

 follows : 



The extract I use* was prepared by Messrs. Wilkins & Brooks, druggists, at Selma, 

 from imported insect-powder, by the repercolation process as prescribed in tho 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 orifices. 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 afterwards 

 and did not seem to have lost much of it» 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 sufiScieut 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 apx)liod 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 applj^ 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 

 X^roved 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 

 l>ortion of the larger worms had recovered, and were again feeding. My experiments 

 woukl 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 experi- 

 ments made in 1879. Professor Jones estimates that 1 pound of powder 

 converted into extract is sufficient to give 100 gallons of liquid, while 



