PYRETHRUM AS USED AGAINST THE COTTON WORM. 177 
Mr. Boh wans calculates 1 pint of extract, or 1 pound of powder, to each 
20 gallons of water ; but bis extract costs only 50 cents in addition to the 
cost of the powder, while that of Professor Jones costs aboutS 3.15 in 
addition to the powder. Allowing 75 cents for 1 pound of Pyrethrum 
and 20 gallons (with the improved atomizing machines) of fluid per 
acre of cotton, we arrive at a cost of 78 cents for Professor Jones's ex- 
tract, made by distillation, and 9G cents for Mr. Schwarz's extract, made 
by repercolation. Taking into account that Mr. Schwarz's extract was 
not a very strong one, the real cost of the application will be nearer the 
former figure. Further experiments will no doubt lessen the cost of 
making a perfect extract, but considering the high price of the alcohol 
necessary to its preparation, Pyrethrum, in the form of alcoholic ex- 
tract, will remain a somewhat expensive remedy. On the other hand 
the extract is extremely convenient to handle, and can be kept for an 
indefinite length of time without losing its efficacy. 
5. Pyrethrum in simple water solution. — That a portion of the 
volatile oil contained in Pyrethrum is soluble in water, was made known 
in 1879 by Professor llilgard ; but that the powder simply stirred up in 
water would prove a most satisfactory and economical method of appli- 
cation was a most encouraging discovery that resulted from the experi- 
ments made at Selma in 18S0. The powder is most readily stirred up 
in water, and the slightest disturbance or irregular movement of the ves- 
sel containing themixture is sufficient to keep the particles in suspension, 
owing to the very light nature of the powder. This is an important 
point, since it has been proved by experiment that the mixture, it' applied 
alter the powder particles have settled to the bottom, is less efficacious 
than when kept stirred up. It is also advisable to apply the mixture 
immediately or at least soon after preparing it, as it gradually loses its 
strength, even if kept in a tight vessel. 
We had intrusted Mr. Schwarz, during his stay at Selma, Ala., with 
conducting experiments with Pyrethrum-water, and he reported as fol- 
lows: 
As I was not prepared to find this method of applying pyrethrum 60 effieient and 
economical as it proved to he, I carried on a number of experiments with a much 
larger proportion of the powder than I found finally to he sufficient to kill the worms. 
The enumeration of these preliminary experiments, in which I was constantly lower- 
ing the proportion of pyrethrum, is therefore omitted as superfluous. 
After many trials I found that 200 grains of powder, stirred up in 2 gallons of 
water, are sufiicient to kill all worms which are brought in contact with the fluid, only 
some of the full-grown ones recovering; that if a weaker mixture is used a portion of 
the average-sized worms recover ; and that very young worms are fatally affected by 
a mixture of 100 grains of powder to 2 gallons of water. 
With the mixture of 200 grains of powder to 2 gallons of water, the following four 
experiments were carried on by myself and Mr. Hubbard, in the latter part of 
September, and each repeated several times, so that but little doubt can be had re- 
garding the correctness of the results. There were plenty of worms on the plants at 
the time. 
Experiment 1. — Two gallons of the liquid applied by means of the fountain pump 
from above, thus imitating the action of any of the sprinklere DOW in u.ge. The liquid 
63 CONG 12 
