Thomson's S_ystem oj' C/iemistn/. 133 



combustion; and the products of the combustion of euchlorine, 

 by a gentle elevation of temperature, and of the chloride and 

 iodide of azote, can be referred to none of the above heads. 

 " Light and heat are always emitted during combustion ; but 

 never when a supporter combines with a combustible without 

 combustion." This is a notable discovery. The phsenomena of 

 combustion do not appear without combustion! Had Dr. 

 Thomson read Sir H. Davy's papers on flame, he would 

 have seen investigations of the relation between the light and 

 heat, emitted in combustion which would have made him 

 ashamed of the ridiculous fancies, with Avhich the above extract 

 concludes. It has been demonstrated many years ago, that no 

 peculiar substance or form of matter is necessary for the effect of 

 combustion ; that it is a general result of the actions of any 

 substances possessed of strong chemical relations, or different 

 electrical relations, and that it takes place in all cases in which 

 an intense and violent motion can be conceived to be communi- 

 cated to the corpuscles of bodies*. It is amusing to find in the 

 Doctor's brief and unsatisfactory abstract of Sir H. Davy's re- 

 searches, two short sentences, which render all his previous argu- 

 ments nugatory. " It is only when opaque bodies are evolved 

 during the combustion of gases, that flame appears. And the 

 intensity of the flame depends upon the quantity of such matter 

 evolved. This notion first advanced by Davy, see?/is correct f." 

 Dr. Thomson should reserve his term notion, for his own crude 

 conceptions ; and pitch upon a more becoming appellation for an 

 experimental truth of the first interest and importance. But he 

 cannot even transcribe without vitiating the statements. Flame 

 consists of light and heat. Now it is the intensity of the light, 

 and not of the flame in general, which depends on the quantity 

 of solid matter evolved, and then ignited. In fact, this 

 " system " seems as if simultaneously written by two dif- 

 ferent hands, neither of which knew what the other was about. 



" If any confidence can be put in the accuracy of the preced- 

 ing tables, (Rumford's), it is pretty obvious, that the quantity 

 of heat evolved in combustion, is not proportional tcr the quan- 

 tity of oxygen which unites with the burning body J." Ashe 

 elsewhere eulogizes Rumford's method of experimenting, we ask 

 what becomes of his opinion so formally announced above, that 

 the " heat which is evolved during combustion is always greatest 

 when the quantity of supporter (oxygen, for example,) which 

 combines with the burning body, is greatest." His fancy of 

 semi-combustion in the formation of sulphurets and phosphurets, 

 " indicating by the term, that it possesses precisely one half of 

 the characteristic marks of combustion," is too grotesque to 



* Sir H. Davy's Elements, p. 223. ♦ Thomson's System, I. p. 145. 

 X Ibid. p. 144. 



