1825.] en the Process of Combu&tion* 35 i 



affinities are again destined to pass away, and having thrown off 

 the forms they had assumed, they serve as the basis of other, 

 perhaps far different compounds. It has been usual to attribute 

 the changes here spoken of almost exclusively to the combined 

 influence of air and of moisture aided by inequalities in atmo- 

 spheric temperature. =^ These no doubt are powerful, and to a 

 certain extent, effective agents ; yet when we come to consider 

 apparently the most simple pha^nomena, how many serious and 

 unbending difficulties have we not to encounter ? The co-opera- 

 tion of an active energetic principle such as that I have sug- 

 gested, would, it appears to me, afford a ready explanation of 

 many miscellaneous occurrences at present involved in much 

 obscurity. Above all, its well-known power of causing the dis- 

 engagement of oxygen from a variety of compound bodies would 

 appear to offer a fair and satisfactory explanation of one of the 

 most abstruse and difficult problems that has as yet engaged the 

 attention of scientific men. "By whatever process," observes 

 IMr. Elhs, " the purification of the atmosphere may be accom- 

 plished, of this general fact we may rest satisfied, that as oxygen 

 is withdrawn from it in order to enter into new combinations, so 

 it can again be restored only by such decompositions as shall 

 set it free, and these decompositions must be as numerous, and 

 to an extent as great, as the combinations to which they 

 succeed." 



I. am fully aware that this is a subject on which even a con- 

 jecture should be hazarded with extreme caution, but I trust its 

 importance, as well as the acknowledged want of any thing like 

 a satisfactory explanation of the principles on which such inte- 

 resting and important changes depend, will furnish an apology 

 for the lew imperfect ideas I have here ventured to throw out. 



Whether chemically acting rays exist in the moonbeams is a 

 point I believe not yet fully determined. It is likely, however, 

 that they do, although in an extremely dilute and attenuated 

 condition. Indeed if the colorization of the leaf is once admit- 

 ted to be owing to the action of these rays (and of this the expe- 

 riments of Senebier appear to leave no doubt), we can hardly 

 hesitate to admit their existence.f The Abbe Lessief ,^nd 



* Matter is commonly divided by chemists and natural philosophers into liviiig abd 

 dead^ but the distinction is probably not founded on rational or accurate views : what we 

 usually term dead matter is by no means inert or indifferent with regard to itself ; there 

 is not a particle of dust on which we tread but has its peculiar relatians and affinities, by 

 which it is enabled to form a portion of that perpetual round of modifications that form 

 so remarkable a feature in the material world. Attraction in fact may be said to consti- 

 tute the life of the inorganic masses of our globe. 



•f Alihough no difference could be detected in the process of combustion when ca^ri^d 

 on by moonlight and in a darkened room, yet this might be owing to the imperfection of 

 the means employed to ascertain the weights of the respective portions of taper. The 

 light of this luminary does not amount to 1 00,000th part of that of the sun, and the very 

 . iieeble heat which this excites has never yet been detected by the most delicate contrivance 

 of art. Such may be the case with the chemical rays : our best devised experiments 

 may hot be able tQ dddect their presence, although feom ft ya^etiy,of,S*!t}irf|.phsp»oiHena 

 their existence is hardly to be (j[uestioncd. 



