PYRETHRUIVI AS USED AGAINST THE COTTON WORM. 177 



Mr. Schwarz calculates 1 pint of extract^ or 1 pound of powder, to each 

 26 gallons of water; but his extract costs only 50 cents in addition to the 

 cost of the powder, while that of Professor Jones costs about$ 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 x^er 

 acre of cotton, we arrive at a cost of 78 cents for Professor Jones's ex- 

 tract, made by distillation, and 96 cents for Mr. Schwarz's extract, made 

 by reper eolation. 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 i)reparation, 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 Hilgard ; 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 1880. 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, if applied 

 after 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 tbis method of applying pyrethrum so efficient and 

 economical as it proved to be, I carried on a number of experiments witb a mucb 

 larger proportion of the powder than I found finally to be sufficient to kill tbe worms. 

 The enumeration of these preliminary experiments, in which I was constantly lower- 

 ing tbe proportion of pyretbrum, is tberefore omitted as suijerfluous. 



After many trials I found that 200 grains of powder, stirred up in 2 gallons of 

 water, are sufficient to kill all worms wbicb are brougbt in contact witb tbe fluid, only 

 some of tbe full-grown ones recovering; tbat if a weaker mixture is used a portion of 

 tbe average-sized worms recover ; and tbat very young worms are fatally afifected by 

 a mixture of 100 grains of powder to 2 gallons of water. 



With tbe mixture of 200 grains of powder to 2 gallons of water, tbe following four 

 experiments were carried on by myself and Mr. Hubbard, in tbe latter part of 

 September, and each repeated several times, so tbat but little doubt can be bad re- 

 garding tbe correctness of tbe results. There were plenty of worms on tbe plants at 

 tbe time. 



Experiment 1.— Two gallons of tbe Uquid applied by means of tbe fountain pump 

 from above, tbus imitating tbe action of any of the sprinklers now in use. Tbe liquid 

 63 CONa 12 



