in the different iCrnds of Gas, and in Fluids, 133 



and in others is weakened or completely checked, that I 

 consider it as my duty here to insert them ; for coincidence 

 with the unprejudiced opinion of a great man is always ad- 

 vantageous to a writer, and when thrown into the scale 

 adds no small weight to an assertion. M. Humboldt says, 

 '' When the equilibrium between the component parts of 

 organized matter is destroyed, and the important chemical 

 process of putrefaction begins, it is variously modilied by 

 the temperature and nature of the surroundmg mediums. 

 Every fermenting substance, therefore, changes eveiy mo- 

 ment the state of its mixture ; and as its natural phospho- 

 rescence depends on this change of mixture, every thing 

 that relates to the one must increase or destroy the other. 

 There are two conditions, therefore, imder which rotten 

 wood is extinguished, one of which has an immediate and 

 the other a mediate action. The first is only oxygen gas ; 

 the other, heat, oil, acids, alcohol, &c. Decomposition 

 with the disengagement of light ceases until a new access 

 sion of oxygen gas. But the putrescent substajice in con- 

 tact with oxygen gas is brought to a new state of mixture 

 by elevation of temperature, and quits its former state of 

 putridity, which is an essential condition of the disengage- 

 ment of light." 



If the determinate decree of putriultv is totallv changed 

 or destroyed by certain mediums, the extinguished lieht of 

 the wood cannot be again revived ; but if these fluids have 

 exercised on the wood only a weak action and for a short 

 time, and if the degree of the putridity be therefore only 

 as it v/ere superficial, the phosphorescence in this case may 

 be again revived and strengthened by means that promote 

 putridity, and consequently by moistening, exposure to at- 

 mospheric ail-, &;c. 



1, however, freely confess that it still appears to me diffi- 

 cult to explain, in a definitive manner, how wood in this 

 phosphorescent state is decomposed, and what its luminous 

 appearance really is. I have however formed several ideas 

 on this subject, but they do not aj^pcar to me to be yet fit to 

 be laid before the public. Nor will I venture to determine 

 how near the truth the opinions of iSpallanzani, Carradori, 

 Humboldt, and Gartner, approach. I am inclined to 

 think that time and experience arc still necessary to bring 

 them to maturity. This nmch,- however, is certain, that to 

 produce such phosphorescence several particular circum- 

 istances are neccssarv, otherwise this phaenomenon would 

 pccur much oftencr in nature, 



J^XV. Com 



