f 4 On the Light emitted Inj rotten JVooi 



Experiment VI. 



I prepared impure phosphoric azotic gas by combustion 

 and long exposure to heat, with a sufficient quantity of 

 phosphorus shut up in a close vessel with atmospheric air. 

 In this gas a piece of rotten wood continued luminous for 

 an hour. Having introduced another piece of wood, thtt 

 phosphorescence was the same as before ; and at the same 

 time artificial phosphorus emitted no light. 



Experitnent VII. 



Rotten wood appeared phosphorescent in hydrogen gai?, 

 prepared from iron and sulphuric acid, in which phosphorus 

 emitted no light ; but in the course of 30 or 40 minutes it 

 considerably decreased, and at length became entirely ex- 

 tinct. By the contact of atmospheric air the light was in 

 some measure revived. As often as a fresh piece of rotten 

 wood was introduced into the remaining gas, it became lu- 

 jninous. This experiment I several times repeated with the 

 same result. 



Experiment VIII. 



Having placed rotten Wood in carbonic hydrogen gas, 

 prepared from the saw-dust of the beech tree, it became lu- 

 minous at first, as in atmospheric air ; but after 45 minutes 

 the phosphorescence gradually decreased, and in about an 

 hour entirely ceased. Every time I introduced a fresh- piece 

 of wood into the remaining gas I observed the same result. 

 Artificial phosphorus in this gas gave no signs of light 

 whatever. 



Experiment IX. 



I introduced rotten wood into phosphorated hvdrogen 

 gas above a year old, during all which time a considerable 

 piece of phosphorus had remained in it, and which had been 

 continually exposed to the solar heat. In this gas the wood 

 continued luminous without any decrease of its intensity. 

 At the end of an hour the light began to decrease, and in 

 an hour and a half it had almost entirely ceased. Fresh wood 

 ■introduced into the remaining gas exhibited the same phae- 

 nomena: artific.al phosphorus however gave no signs of 

 light. 



Experiment X. 



I prepared fresh phosphorated hvdrogen gas, which, as h 

 \vell known, is so unfavourable to the luminous property of 

 phosphorus, even in small quantity, in azotic gas or atmo- 

 spheric 



