120 Facts, Observations., and Experiments, relative 



In azotic gas, when perfectly pure, I have not tried 

 these insects ; but having accidentally had this gas 

 mixed with a portion of atmospheric air, I found them to 

 shine less vividly in it than in the atmospheric air, which 

 I kept as a standard. 



In oxygenated muriatic acid gas, they emit a few 

 flashes very quickly in succession, on their first immer- 

 sion ; and the flashes are of a redder, though I can hardly 

 say of a more brilliant, light, than the ordinary emana- 

 tion. They then die. In the course of six or eight 

 hours, they are found bleached perfectly white. * * * 



When confined in oxygen gas, obtained from manga- 

 nese, they instantly give out a light much more brilliant 

 than I ever saw before ; and this light they have not the 

 power to diminish, though they can increase it, for some 

 time. 



These insects live longer in this than in any of the 

 other gases, but die, in general, in the course of two or 

 three hours. But some have lived eight and ten hours. 



Whether dead or not, they continue very brilliant for 

 twenty-four hours, more or less. Six or eight of the 

 insects put into a vial* produce a light so vivid, and of 

 such a peculiar brightness, that the eye can hardly 

 bear it. 



The part from which they give out their light is the 

 lower or posterior and inferior part of the abdomen. 



* I presume of oxygen yu<;. Editor. 



