26o The Control of Mosquitoes 



short time necessary for its evaporation, and the fact 

 that it leaves a very slight residual odor, which 

 quickly disappears, so that the houses are comfortably 

 habitable as soon as the cleaning-up process is com- 

 plete. In such cases it has given quite as good 

 results as sulphur, and, considering everything, is 

 much the cheapest fumigant of the three. 



