J- 821.'] Causes of Calorific Capacity, Latent Heat, Sfc. 271 



the higher the temperature, the more vigorously, of course, will 

 these efforts to condense be resisted. 



Thus the difference between condensible and permanent airs, 

 as I have before hinted, may be entirely owing to the figures 

 and, perhaps, the size of the component parts ; and hence 

 we have the greatest latitude for explaining the different pheno- 

 mena. An extreme minuteness and a perfect sphericity, or a 

 total inadaptation in the particles, would probably resist every 

 effort to produce condensation unless the temperature could be 

 entirely destroyed. Hence the reason that common air, which 

 is composed of oxygen and nitrogen, could not be condensed 

 though the compression has been carried so far as to make the 

 air heavier than water. The particles of oxygen and nitrogen 

 may not indeed be exceedingly small, nor their figures be in 

 anywise spherical, but their inadaptation may be so great as to 

 render condensation extremely difficult. 



Ammoniacal gas aided by pressure and a low temperature has 

 been condensed to a liquid, but by no methods yet devised have 

 the other gases been separately condensed. Now these things 

 may entirely be owing to a certain mutual adaptation of figure 

 in the one instance, and a much less, or, perhaps, scarcely anv 

 at all, in the other cases. 



Though the particles of an aeriform body may have amono- 

 one another little or no adaptation, and hence render the bodv 

 incapable of being separately condensed, it may however, hap- 

 pen, that the particles of two such bodies may have so great an 

 adaptation as to render it difficult to keep them together without 

 condensing. An instance of this kind is found in sulphurous 

 acid gas and sulphuretted hydrogen gas ; for when two in 

 volume of the former are mixed with one in volume of the latter 

 the mixture slowly condenses into a solid. The same pheenome- 

 non occurs in a mixture of ammoniacal and muriatic acid gases, 

 except that the solidification in this case is almost instantaneous. 



Theory of the Influence of external Pressure on the Temperatures 

 of Ebullition in Fluids, and Liquefaction in Solids. 



I have already stated that I cannot fully enter into my views 

 of ebullition on account of their being so closely connected with 

 a subject which would lead me to, indeed, some very important, 

 but more extensive investigations than I have at present leisure 

 to attend to. It is of course without the pale of my views now 

 to explain in detail the cause of the effect which pressure has on 

 the temperature of ebullition. Lest, however, the general theory 

 1 have given should appear defective by the omission of one of 

 the most difficult and interesting parts of it, I will just glance at 

 the leading feature of ebullition, and reserve a detail of my views 

 of the minutiae to another opportunity. I have shown that the 

 'ire gularity of figure in the particles of vapour is the cause of its 

 condensation at all temperatures beneath that of its generation ; 



