PYEETHRUM POWDERS 367 



Doctor Dade continued to experiment with this remedy after his return from an 

 unsuccessful attempt to capture General Aguinaldo, and found that the addition 

 of one part oil of bergamot to sixteen of kerosene imparted an odor scarcely ob- 

 jectionable, and at the same time added sufficient body to the kerosene to pre- 

 vent evaporation in less than six to eight hours. After that, when the soldiers 

 had to leave the post, and after it became impracticable to carry cans with them 

 in the field for a long or protracted march, this mixture was used with the result 

 that the list of malarial patients was noticeably shortened. The oil of bergamot 

 was hard to obtain and is too expensive to be used wholesale, but the soldiers 

 rarely objected to the odor of kerosene and the bergamot was not continued. 



In moist tropical regions where one perspires profusely, the oily mixtures 

 on the skin considered under this heading are transient in their effects. Under 

 these circumstances they should be applied rather liberally to the clothing, 

 particularly about the neck and wrists. 



SMUDGES AND FUMIGANTS. 



Hunters and campers have been in the habit of using almost anything that 

 will make a dense smoke as a smudge to drive away mosquitoes. In Bermuda, 

 fresh cascarilla bark is burned for this purpose, and elsewhere other green bark 

 and vegetation. For household use, however, a number of different substances 

 have been tried. 



PYRETHRUM OR CHRYSANTHEMUM. 



For many years finely ground powders known as pyrethrum powder, chrys- 

 anthemum powder, Persian insect powder, or Dalmatian insect powder, have 

 been used to kill insects. They became famous for their insecticidal effects long 

 before their composition was known. Their use seems to have originated in 

 Asiatic countries beyond the Caucasus Mountains. The powder was sold at 

 high price by the inhabitants and was brought by merchants to Eussia and 

 western European countries. The nature of the powder was kept a secret until 

 the beginning of the last century, when an Armenian merchant, Mr. Jumtikoff, 

 learned that the powder was obtained from the dried flowerheads of certain 

 species of composite plants of the genus Chrysanthemum (Pyrethrum) growing 

 abundantly in the region now known as Transcaucasia. The son of Mr. Jumti- 

 koff began to manufacture the article on a large scale in 1828, and since then the 

 pyrethrum industry has steadily grown and now the export in dried flowerheads 

 from that part of the country is very important. 



The species grown commercially in the Transcaucasian region is Chrysan- 

 themum roseum. The species grown in Dalmatia is C. cineraricefolium, and the 

 crop in Dalmatia, Montenegro and Herzegovina is now the principal source of 

 the powder in commerce. Thirty years ago it was considered the most valuable 

 export of Dalmatia. The best powders are made from the dried flowerheads of 

 these plants. The essential principle resides in the oleoresins, which are 

 fugitive, so that the strength of the powders disappears with age or exposure. 

 Powders imported from Europe are not so strong as powders made in this 



