1822.] Causes of Calorific Capacity j Latent Heatj 8^c. 19 



trisected. In the combination of hydrogen with chlorine to form 

 muriatic acid gas, the particles of hydrogen are still further 

 divided ; and I have reason to believe there are other cases in 

 which the division is carried to a much greater length. I have 

 often sought for some satisfactory reason that philosophers 

 might have for ranking hydrogen among the elements, but have 

 not yet met with any. Sir H. Davy thinks the great levity of 

 hydrogen is an argument in favour of its elementary nature. 

 Levity may certainly induce us to think that the body in which 

 it most predominates approximates the nearest to an elementary 

 substance ; but in such a case as this, it can, it appears to me, by no 

 means be considered a proof, or even a probable argument, of hy- 

 drogenbeing an element. For instance, ifhydrogen be esteemed an 

 element because it is about Mf lighter than common air, among 

 what bodies must we rank light whose levity to that of hydrogen 

 has, in the strictest sense of the word, no appreciable ratio ? 

 Yet this very body, hght, we have good reasons for beheving, 

 consists of molecules of at least seven different sizes ; and it is 

 not absolutely certain that even these molecules are indivisible 

 atoms. Even the implied size of the particles of hydrogen has, 

 I think, from its levity, been considerably overrated. Accord- 

 ing to the theory I have demonstrated, it appears that the 

 diameter of a particle of hydrogen is more than two-thirds that 

 of a particle of nitrogen. Surely then there can be no argument 

 gained in favour of the simplicity of that body from the smallness 

 of its particles, especially as nitrogen is considered to be a 

 compound. 



There is no direct method of ascertaining from the old theory 

 the relative sizes of the different gaseous particles ; but from the 

 results of some experiments it seems possible to arrive at some- 

 thing like a ratio. Thus in the formation of muriatic acid gas 

 from the exposure of equal parts by volume of chlorine and 

 hydrogen to common day light, we have evidence enough, if the 

 old theory of gaseous repulsion be true, to demonstrate that 

 equal volumes of hydrogen and chlorine contain equal numbers 

 of particles ; and, consequently, that the diameters of the hydro- 

 gen and chlorine particles are respectively as 1 and 3*3. These 

 dimensions, therefore, could be esteemed very little more an 

 argument in favour of the elementary nature of hydrogen than 

 those drawn from my theory. In fact I can discover no one 

 phsenomenon whatever which sanctions the probabiUty of hydro- 

 gen being a simple body. Its combustibility is by no means an 

 argument in favour of such an idea; and the size of its particles, 

 any how computed, is rather an argument of the contrary. The 

 superior disposition it exhibits to combine with other bodies, 

 which SirH. conceives is partly demonstrative of its elementary 

 nature, I think I shall be able to prove is due to a very different 

 cause. 



Another important consequence seems to flow from my inqui- 



c2 



