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



changes of state from the solid to the fluid, from the fluid to the 

 aeriform, and vice versa; and we have seen that in general, 

 changes from the solid to the fluid, and from the fluid to the 

 aeriform state, are accompanied with an increase in the numera- 

 tom as referred to equality of weight, and, consequently, with a 

 diminution of temperature. On the contrary, in changes from 

 the aeriform to the fluid, and from the fluid to the solid state, a 

 diminution in the numeratom, as referred to equality of weight, 

 -will generally be the case, which will be productive of an 

 increase of temperature. These conclusions, though holding 

 pretty generally, are by no means to be considered as universal 

 laws. Instead of an increase of temperature in the condensation 

 of vapours, and the solidification of fluids, or a diminution in the 

 vaporisation of fluids, and the liquefaction of solids, we may 

 either have the very contrary, or no change of temperature at 

 all, and by no means violate our general views. We have 

 already shown that the liquidity of bodies depends on two cir- 

 cumstances ; the sphericity and the extent of the aberrations of 

 the particles. Were the particles perfectly spherical, the body 

 would be perfectly fluid ; and even if they were not, a perfect 

 fluidity may be obtained by only giving them such a range of 

 ■vibration as would carry them beyond the irregularities of their 

 figure. Therefore, if we suppose a decomposition to take place 

 in the particles, in the manner we have before described, a 

 Tecomposition may be so effected as to make the new particles 

 not only more spherical, but, perhaps, of an equal or less num- 

 ber ; in which cases a perfect fluid may be formed with an equal 

 or even a higher temperature, than the solid had from which it 

 was derived. For the converse reasons a solid may be formed 

 from a fluid of an equal or an inferior temperature. I cannot 

 say that I can call to mind any particular instance of this kind, 

 nor will the short time I have to prepare for the press allow me 

 to make any researches ; but surely nothing can be a greater 

 proof of the beauty and probability of a theory than this very 

 extensive generality I have shown it to possess. 



Some idea of the cause and manner of union between the par- 

 ticles of aeriform bodies, and the consequent condensation will 

 be given in a subsequent part of this paper, on which account I 

 shall not stop here to detail it ; but we may anticipate that the 

 particles of two distinct gases may have a very great adaptation 

 of figure, though the particles of either gas alone have little or 

 no adaptation. The particles of two such gases mixed together 

 would speedily form a union either with or without condensation, 

 according as this union does or does not dispose the particles to 

 a further aggregation. But if it should not so dispose them, an 

 increase of temperature and specific gravity will be the conse- 

 quence. An example of this kind of union is found in the form- 

 ation of carbonic acid gas from a mixture of carbonic oxide and 

 oxygen, though the combination requires the assistance of an 



