\ 50 On the Light emitted hj rotten JVood 



is luminous only in azotic gas, oxidated azotic, gas, an4 

 muriauc acid gas. 



Sdly, In muriatic acid gas it inflames immediately of itself, 

 and burns with great brightness. 



4thly, The light of phosphorus is stronger in rarefied air. 



5thly, It emits no hijht in vacuo. 



6ihly, On being subjected to heat, it inflames and burns 

 with rapidity in oxygen gas ; and in the non-respirable 

 gascsj not pure, its light is stronger. 



7thly, By its phosphorescence m oxygen gas no carbonic 

 acid is ibrmed. 



Sthly, When artificial phosphorus has emitted light in the 

 non-rcspirablc gases not perfectly freed from oxygen gas, 

 a fresh piece of phosphorus does not become luminous in 

 them : azotic gas, however, is an exception, in which, after 

 being punfied, phosphorus becomes luminous for sometime. 



9thly, Moisture and wet are impediments to its being lu-» 

 minous. 



lOthly, Fluidsarealtogelher contraiy to the luminous pro- 

 perty of artificial phosphorus. 



Phosphorescent wood, therefore, differs essentially from 

 artiiiciai phosphorus by the conditions requisite for its being 

 lominous ; and therefore the assertion of Spallanzani, that 

 the greatest analogy exists between the luminous phaenoi- 

 mena of these two substances must lose some of its weight. 



If I mistake not, the following probable conclusions may 

 be deduced from the above experiments : that the extinction 

 of the light of rotten wood in different mediums does n&t 

 so immediately arise from a want of oxygen gas as from 

 gome change which the wood itself has experienced. For 

 even if, according to the opinion of Humboldt, Spallanzani, 

 and other philosophers, the oxygen gas concealed in difle- 

 rent mediums be the immediate cause of its phosphoresr. 

 cenee, in several experiments where rotten wood was im- 

 mersed indiflerent mediums 1 must have observed no light : 

 at any rate, the phosphorescence must always have beerx 

 weaker, and tresh wood repeatedly introduced would no 

 longer have been luminous in itj which is contrary to what 

 I expe. enced. 



Besides, how difficult would it be to prove, with any de- 

 gree of probability, that the undiminished phosphorescence 

 of wood, which IS obsfirved in distilled water and in oil, 

 arises Ijom a ginall quantity of oxygen gas in the.-.e fluids? 

 And is the luminous wood, placed in these fluids, capabk 

 of decomposing' yxygen gas with which it is so little, in con- 



tact. 



A 



