to explain the Vbiencmena of Comhii/Iion. zc^ 



the body that has undergone combuflion. Thefe important 

 fafts led to the adoption of a new theory of conibuftiou well 

 known at prefent by the name of its iiliiitrioiis author. 



The theory of Lavoifier is founded on the abforption of 

 oxygen by a combudible body, and proceeds upon the fol- 

 lowing principles : 



lit, That combudion never takes place without the pre- 

 fence of oxygen gas, 



adiy. That in every combuflion there is an abforption of 

 oxygen gas. 



3dly,That there is an augmentation of weight in the pro- 

 duces of combultion equal to the gas abforbed j that the oxy- 

 gen Hkewife imbibed by the combuftible body may be ajain 

 recovered from the compound formed, and the weioht^re- 

 gained will be equal to the weight which difappeared during 

 combuftion. 



And, lailly, That in all cafes of combuftion there is a dif- 

 engagement of light and heat. 



Thefe facts have been eftabliOied by the moft accurate ex- 

 periments, and are too well known to require any. further 

 illuitration; they incontrovertibly prove the general princi- 

 ple, " that combuliion is only a play of affinities between ox- 

 ygen gas, caloric, and the bafe of the combuftible body. It is 

 a further part of this theory, that the light and caloric which 

 are evolved during combuftion proceed from the oxyeen tra?, 

 and that they are not emitted, as (hould follow from the phlo- 

 giftic do6frine, from the combuftible body. 



As this theory, however beautiful, is not capable of ex- 

 plaining with clearnefs and accuracy many of the pheno- 

 mena of combuftion, Dr. 'i'homfon, of Kdiuburgh, ha? 

 lately (fee Nicholfon's Journal, New Series, for May and 

 June i8oz,) oflered another which places this fubje(il in ;i 

 point of view fomewhat diHerent,- and which certainl^^ bids 

 fair to enable us to eftimate tbe phtenomcna of combuftion 

 with more fuccefs than has hitherto been done. Chemifts 

 have been lately accuftomed to give to the term combuftion. 

 according to the foregoing thef)ry, a new meanin<r, and to 

 make it ftand for the general coiiihination of a bodv with 

 oxygen. Nothing, however, can be more evident than the 

 difference that in numberlcfs inftanccs prevails between the 

 aft of oxygenation of bodies and that of condjuiiion, inaf- 

 much as neither the phfenomena attending them, nor the 

 refults arifing therefrom, are the fame. 



It isprobahle tiiat this error has :iriren from ilie conlidcra- 

 tion that all bodies during their cwnib^iftioti comhine witl\ 

 ♦jxygcn, wiliiout at the )'ai|ie time rccullciitiiio ih:it this latter 



tftca 



