264 Mr. Herapath on True Temperature, and the [Oct. 



very inconsiderable rise of temperature takes place. " Sulphu- 

 rous acid gas and ammonia, sulphuretted hydrogen gas and 

 ammonia, both of which condense into a solid salt when mixed 

 in equal volumes, occasion a still smaller elevation of tempera- 

 ture."* These, and other instances of the kind, which it is easy 

 to adduce, though confessedly of the utmost difficulty to be 

 accounted for on the calorific hypothesis, are very easy conse- 

 quences of the theory I have given. 



Again, let us conceive a solid or fluid composed of particles^ 

 the parts of which, to put the theory under the most unfavoura- 

 ble circumstances, we will suppose, are united by their most 

 adaptable sides. Then though in any particle these contiguous 

 sides be the most favourable for union, and, consequently, the 

 other more exterior sides be less favourable, yet such may be the 

 relation of these contiguous sides that their mutual adaptation 

 may be much less than the adaptation they have for the like, or 

 probably interior sides of similar or other parts of other particles* 

 While the body, therefore, continues in its present state, these 

 sides of superior adaptation in the different particles cannot come 

 in contact, because they are already in contact with other parts 

 of their respective particles ; and thus, when the particles meet, 

 are turned from, rather than towards, one another. No decom- 

 position and other combination can, consequently, in this state 

 of things take place. But if we suppose the particles of a small 

 part of the body to be by any means decomposed into an air, the 

 lowness of the temperature of the new particles, as we shall here- 

 after show, arising from the decomposition, may very much con- 

 tribute to unions between the most adaptable parts. Nor is 

 there any reason why, if the figures of the particles favour it, 

 that the unions may not be carried to a length sufficient to make 

 the number of the particles of the decomposed mass less, and, 

 consequently, their magnitude and temperature greater in the 

 gaseous than they were in the solid state. This being the case, 

 the gaseous particles may strike with a force sufficient to 

 decompose another such a mass, or, perhaps, more of the body; 

 and this being in like manner gasefied will produce a similar 

 effect on another portion, and so on until the whole body is con- 

 verted into gas with a rapidity, perhaps, in appearance, equiva- 

 lent to a total instantaneous explosion, and with a rise of 

 temperature proportioned to the aggregation of the particles. 

 Thus the explosion of a single particle may be sufficient to 

 explode the whole mass, however large a quantity it may be. 

 The confirmation which is given of these views in the explosion 

 of gunpowder, fulminating argentum, fulminating aurum, &c. are 

 too trite and familiar to need any comment. 



Whatever differences exist between powders of this kind may 



• Thomson's System of Chemistry, i. 75. 



