in the different Kinds of Gas, and in Fluids. 149 



continued luininous in hvdrogen gas in which another piece 

 had emitted light, a much shorter time than in gas which had 

 not been Ijcfore used. I do not remember to have ever found 

 aiu" remark of this kind in the works of others ; and as I 

 paid particular attention to this point, in regard to every other 

 kind of gas, I did not find Gartner's observation confirmed. 

 A great part of these variations, however, are probably ow^ 

 ing to this circumstance, that the wood employed was not 

 of the same kind, and had not the same degree of rotten- 

 ness and moisture. All our experiments, however, coincide 

 as much as could be expected from the use of a substance 

 such as phosphorescent wood. 



If we still further compare the phisnomena of rotten wood 

 with those of phosphorus, the following differences will be 

 observed between these suiDstanccs : 



Fhospliorescent JVood, 



1st, Is luminous in oxygen gas at low temperatures. 



2dlv, It is phosphorescent in all non-respirable gases, at 

 least a short time, and in several of them in a pretty contir 

 nued manner 5 as in phosphorizcd oxygen gas, and pnospho-r 

 rized azotic sas, 



3dlv, In muriatic acid gas its light is soon extinguished. 



4thly, Its phosphorescence in rarefied air is weaker. 



5th!v, It emits light in a Torricellian vacuum, according 

 to the testimony of Carradori. 



6ihly, Its light becomes extinct both in oxygen gas and 

 in other gases when heated, 



7thly, By the process of its phosphorescence in oxygen 

 gas carbonic acid gas is produced. \ 



8thlv, The phosphorescence of rotten wood can be ex- 

 tinguished several times successively in the non-respirable 

 gases, whether they contain oxygen gas or not, without the 

 property of the gas to maintain the phosphorescence of a new- 

 piece of wood introduced into it being perceptibly lessened. 



pthly, Moisture promotes the phosphorescence of rottcrj 

 wood, and is essentially necessary for that purpose. 



lOthlv, Rotten wood emits light also under water, in oil 

 ^nd in other licjuids, Its splendour in some of theqi is cvci\ 

 heightened, 



KunheVs Phoiphonis, 

 1st, It becomes luminous in oxygen gas only at a teniT- 

 pcrature of about 1 6^ to 22" of Reaumur. 



2dly, Of all the non-rcspirable gases as pure as possible^ it 

 K3 U 



