164 PHOSPHORESCENCE. LECT. VIII. 



shone feebly, when the gas was introduced, the light con- 

 tinued for some time. In both of these cases, I analyzed 

 the gas forty-eight hours afterwards. Its volume had not 

 varied, and the absorption by potash did not exceed 0*2 

 cubic centim. in 8 cubic centimetres of oxygen gas, in the 

 experiment where the light had continued; and in the other 

 there was no absorption ; the oxygen remained apparently 

 pure. 



In another experiment, I heated twenty luminous seg- 

 ments to -f 40 Reaumur [=122 Fahr.], by putting the 

 tube, in which they were contained, into water of this tem- 

 perature. The segments became red, and ceased to glow. 

 I then rilled the tube with mercury, and, inverting it over 

 the trough, introduced oxygen. I perceived no light; and 

 after four days the potash absorbed nothing. These seg- 

 ments had not evolved light; oxygen had not been absorbed ; 

 and consequently carbonic acid had not been produced. 



Effects of Sulphuretted Hydrogen. Some glow-worms, 

 put into sulphuretted hydrogen, quickly ceased to glow and 

 to live ; and they did not afterwards become phosphores- 

 cent, by placing them in contact with oxygen, or by warm- 

 ing them. Some of the luminous segments evolved a very 

 feeble light when they w r ere crushed. 



Effects of Ratified Mr. I will describe, lastly, the 

 experiment of putting these insects in highly rarefied air. 

 I placed, in the closed extremity of a long glass tube, some 

 entire glow-worms, and the luminous segments of others. 

 I filled the tube with mercury, and inverted it over a trough, 

 filled with the same liquid as in the construction of a baro- 

 meter. The glow worms and their segments were thus 

 contained in a space where the air was very rarefied. The 

 light ceased in the insects and in the segments almost at 

 the same time; that i's to say, the phosphorescence was ex- 

 tinguished, in both in the course of two or three minutes, 



