COMBUSTION AND DEFLAGRATION. 13-5 



From the foregoing facts and observations, we 

 perceive how partial and erroneous is the pre- 

 valent notion, that under all circumstances ca- 

 loric is a repulsive agent. We find that the 

 caloric of explosion, like that of ordinary combus- 

 tion, is only a liberation of what was previously 

 concentrated around the particles of ponderable 

 matter, and diffused during its dissolution. 



Such is the beautiful simplicity of nature, that 

 a clear comprehension of the law by which the 

 molecules of a salt are aggregated and dissolved, 

 affords a miniature representation of the mecha- 

 nism by which the universe is kept in motion, 

 from the law of gravitation to the no less impor- 

 tant transformations of chemistry. 



It has been shown, that cold, or the abstrac- 

 tion of caloric, produces the same effect on gases 

 as mechanical pressure that is, it diminishes 

 their volumes and condenses them into liquids or 

 solids ; which is effected by lessening the ratio 

 of sethereal or elastic matter, while the quantity 

 of ponderable matter remains the same. If we 

 suppose that the repulsive force of this sether in 

 hydrogen is equal to the weight of 2000 atmos- 

 pheres, it must be attracted with a still greater 

 aggregate force, by the atoms of sulphur and 

 other bodies : for we have seen that when 1 atom 

 of sulphur combines with I of hydrogen, the re- 

 sulting compound, sulphuretted hydrogen, may 

 be liquefied by a pressure equal to 17 atmos- 



