ioO On the Light onltied Inj rotten iVottd 



other mediums : I hoped also that during these researches I 

 might fall upon some new fact or idea, as is often the case, 

 which mic;ht serve to confirm or to throw some new light 

 on either the one or the other of these opinions. As soon 

 therefore as I had procured some phosphorescent wood \ 

 began with it a scries of experiments, a part of which, with 

 the consecpicnces deduced from them, I shall here lay before 

 the public, after I have made a few previous remarks. 



In regard to the wood itself, it was part of the old rotten 

 trunk o"f" a becch-trec, moderately moist, and without any 

 particular mouldv smell. It was not luminous throughout, 

 hut emitted light only from its surface to the depth of a 

 few lines. The luminous parts appeared to have lost in a 

 coiisiderablc degree their resinous particles, Thevwere fria-' 

 bic, full of fibres, and whiter than those parts of the wood 

 which emitted a weaker light, or had no light at all. I 

 preserved the rotten wood in moist filtering paper in a cellar 

 the temperature of which was from 10 to 12 of Reaumur; 

 .and in this place I made my observations during the night. 

 The colour of the light was exactlv the same as that exhi- 

 bited by the light of artificial phosphorus in atmospheric 

 air. 



I used for my experiments, in general, small bell glasses 

 capable of containing from 8 to 14 cubic inches each, hav- 

 ing a neck at the top exactly shut bv corks boiled in wax, 

 through which passed a varnished w ire. I stuck a piece of 

 phosphonis on the wire in the inside of the bell ; tilled the 

 vessel, according to the nature of the gas to be employed, 

 cither with water or quicksilver ; and then placed it on the 

 pn(fumatic tvib. By the press\u-e which these fluids exer- 

 cised on the wood, small air bubbles, which must have been, 

 contained in the substance of the \\ ood, from time to time, 

 escaped ; and therefore before each experiment I took care 

 to immerse the wood in water till no more air ascended, 

 and by these means prevented the gases from being rendered 

 impure. 



Experiment I. 



I fdled a bell with atmospheric air, and preserved it closed 

 by means of water. During the 'first two days the rotteii 

 wood remained luminous; on the third the light was some- 

 what fainter ; on the fourth it had considerably decreased ; 

 and on the seventh the light had entirely disappeared. The 

 wood, when taken out and exposed to the atmospheric air, 

 omitted no light either when dry or when moistened witli 

 water. I then introduced into the remaiiiing gas a piece 

 of wood which was strongly phosphorescent: it emitted a 



briglit 



