105 CHEMICAL THEORY. 



Dissertatujn op state my objections to these opinions, I shall proceed to no? 

 the natore and ^j^g y^^^ oxipen, and inflammable bodies. 



eiiects of heat, a ' fa ' 



liRlit, and com- Light, like beat, according to some, is a property caused 

 biistiou. ^y ^{-jg vibration of a very snbtile fluid which fills all siace, 



and which undulation * is product d by the sun, and other lu- 

 minous bodies. According to others, it is a real substance, 

 emanating ffom luminous bodies in strait lines, f and v hich 

 by approaching our eyes gives the sensation of light. In 

 obeaience to this, therefore, I shall suppose it a substance, 

 and like heat, capable of existing in a latent sensiLle form. 

 The first is that which affects our organs of vision, the seco d 

 as a component part of a substance, with which it is in che- 

 mical union, but from which, by the action of certain sub- 

 stances on it, may be expelled and rendered sensible. V/he-- 

 ther light be able to combine with more substances 

 than one, I cannot at present determine, but from many ap- 

 pearances, which are familiar to chemists, I am apt to be-' 

 lieve that it is. 



Infiiunmable substances have been usually considered as 

 elements, hut I am under the necessity of calling them all 

 compounds, X ^^^^'^ consisting of a base and the condensed 

 matter of heat. This opinion indeed, does not appear to be 

 peculiar to myself ; for an excellent chemist, who has published 

 an extensive chemical work, appears to think them binary 

 compounds, as consisting of a base and light. Of these sub- 

 stances there are various kinds, each elementary combustible, 

 consisting of its peculiar base j but they all resemble each 

 other in this, that each one contains in composition the con- 

 densed matter of heat, but that in different degrees of cohe- 

 sion, some very easily part with it, as sulphur, phosphorus, 

 &c. but from others it can scarcely be expelled, as the me- 

 tals. Some philosophers have supposed that these substances 

 consist of a base, and the matter of light. 



Oxigen gas has been by many supposed to be a compound 

 of heat ; and a base, § some have, reckoned it a ternary com- 

 pound, consisting of a base, heat, and light; |1 but I, as was 

 before observed, take it to be a combination of the condensed 



* IJiiv7ens. Euler. f Newton. J Thompson. 



^ iMurriiY ct alii. |j BrugnntcUi, Lavoisier, &c. 



matter 



