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XIV. On the Atomic Theory. By William Higgins, Esq. 



To Mr. Tilloch. 



Sir, — X ou will oblige me by inserting in yonr Magazine, 

 which is one of the least prejudiced channels of conveyance we 

 have at present, the following paper. The first part is only pre- 

 liminary to my theory respecting the connexion of light and 

 caloric. 



According to our present knowledge of chemical philosophy, 

 the four imponderable elements with which we are acquainted, 

 viz. caloric, the electric fluid, light, and the deoxygenating rays 

 which accompany light, are the only agents in the hands of Na- 

 ture to effect her operations, and to preserve ponderable matter 

 in the state we constantly find it. They are said to be impon- 

 derable, because hitherto they have been found to possess no 

 sensiijle weight; but as they are capable of uniting to ponderable 

 bodies, they must gravitate towards them, and consequently must 

 have some degree of weight, be it ever so small. 



Every one of the imponderable elements has important duties 

 to perform ; and although apparently clashing or opposite duties, 

 yet they all tend to uphold the great fabric of the universe, and 

 to promote the grand and mighty objects of the Creator. 



Should all the substances of our globe be only influenced by 

 attraction, there could exist in Nature but solid matter ; even our 

 atmosphere would become a solid mass; — animal and ve2;etable 

 life could no longer exist, and the whole face of the earth would 

 exhibit a dreary and inanimate scene. 



Caloric from its peculiar properties seems to be the agent em- 

 ployed by Providence to counteract such fatal effects ; to modify 

 or check attraction, and in many instances to almost wholly over- 

 come it; and although these powers are constant antagonists, 

 their respective and opposite forces are so balanced as to answer 

 all the purposes of life, or animated nature. 



We have every reason to suppose that caloric is a simple ele- 

 mentary matter; it is a fluid universally diffused, and in excess 

 is capable of fusing or converting into the gaseous state all bodies 

 by removing more or less distant their particles, or atoms, or 

 molecules, as it may happen, from each other, at the same time 

 that their temperature is most frequently increased. 



Caloric possesses the property of uniting to bodies chemically 

 without raising their temperature, or changing their state ; we 

 call it change of state in bodies when they pass from the solid to 

 the fluid state ; or from the fluid to the gaseous state. However, 

 substances in the same state and of equal temperature often 

 contain different portions of caloric: this perhaps depends upon 

 Vol. 51. No. 238. Feb. 1818. F their 



