194 MOSQUITOES 



treated upon a large scale and out of doors, but if a labo- 

 ratory experiment fails it may be taken for granted that 

 the outdoor trial will fail even more disastrously. It is 

 for the reason that the much-quoted experiments of Celli 

 and Casagrandi were apparently small-scale experiments 

 that we in the United States have been inclined to give 

 little weight to them. They experimented with a great 

 number of products and decided that petroleum, certain 

 aniline dyes, and vegetable powders made from pyre- 

 thrum or chrysanthemum plants (which form the so- 

 called Dalmatian and Persian insect powders) are the 

 only substances which are to be recommended. Of the 

 aniline dyes they recommend especially a substance 

 which they call in their published work " Larycith 3," 

 and under this name the writer mentioned it in his Gov- 

 ernment bulletin. Every effort was made to ascertain 

 what this substance might be, and it eventually dawned 

 upon me that it might be a misprint for " Larvicide 3." 

 Under this apprehension, Mr. Matheson, who, by the 

 way, is a manufacturing chemist, succeeded in obtaining 

 samples of the substance and in analyzing it. He finds 

 that it is nothing but dinitrocresol, which is an insecti- 

 cide that was formerly highly recommended, but which 

 is now scarcely used at all on account of its very poison- 

 ous character. It was used, in a solution of one pound to 

 fifteen gallons of water, against caterpillars in Bavarian 

 forests, and has been used to some extent as a germi- 

 cide in washing down the walls of sick-rooms and also 

 in washing the outside of brewers' casks to prevent 

 mould and fungi. Its poisonous qualities would make 



