ill the different Kinds of Gas, and in Fluids. CS 



spheric air : in this gas the rotten wood was exceedingly 

 luminous. Even at the end of an hour and a halt" I ob- 

 sen^ed no decrease of the light; and it did not cease en- 

 tirely till the end of several hours. Having introduced a 

 piece of fresh wood, at the end of 24 hours it w?,s as lumi- 

 nous as in atmospheric air, and the case was the same with 

 the 4th and 5th piece which I afterwards brought into con- 

 tact with it. At the conclusion of this experiment I could 

 easil}' inflame the single bubbles of gas by means of a burn- 

 ing coal. 



Experiment XI. 



I introduced into a common bell glass over mercury 

 strong fuming sulphurized hydrogen gas, disengaged from 

 a solution of alkaline sulphuret and tartaric acid. A piece 

 of rotten wood placed in this gas immediately ceased to be 

 phosphorescent. If taken out when the light began to be 

 extinguished, the light could in some measure be revived by- 

 washing it with water in atmospheric air. A fresh piece of 

 woad introduced exhibited the same phsenomenon. Want 

 of oxygen gas was not, in some cases where this experiment 

 was repeated, the cause of the light being suddenly extin- 

 guished ; for the gas was not always perfectly pure. Arti- 

 iicial phosphorus would even at times emit in it a faint 

 vapour. 



Experiment XII. 



In carbonic acid gas prepared with proper care from 

 chalk and sulphuric acid diluted with water, and in which 

 phosphorus, partly by a natural heat and partly by gentle 

 heating in a vessel with hot water, had entirely ceased to be 

 luminous, a piece of rotten wood retained at first its full 

 phosphorescence: the phosphorescence however in the 

 course of four or five minutes considerably decreased, and 

 in 15 or 20 minutes no light was to be seen. Wood which 

 had thus lost all its luminous appearance, when washed with 

 water, seldom recovered its phosphorescence : if however it 

 retained any light when taken, out, it was somewhat 

 strengthened in atmospheric air, but after some time 

 greatly decreased, and af length entirely disappeared. 



Rotten wood exhibited almost the 'jame phaenomcna in 

 carbonic acid gas, prepared with great care, but in which iio 

 phosphorus had previously been exposed. 



Experiment XIII. 



Having brought nitrous gas, mixed with about 0*11 

 part:- of azotic gas, into contact with a piece of rotten 



woodj 



