156 Henry Clifton Sorby, Esq., on the 



One most important circumstance connected with the above ex- 

 pressed views is the very interesting connection which exists between 

 the volume of the atoms and specific heat of the four species. It 

 has long been known that the specific heats of the different forms 

 of carbon vary very much, and exhibits a simple relation to one 

 another, but, so far as I am aware, their true connection has been 

 overlooked. Gmelin, in his Hand-book of Chemistry (Cavendish So- 

 ciety's Translation, vol. i., page 244), when alluding to the relation 

 between the equivalents of elementary bodies and their specific heat, 

 says, " The capacity for heat of carbon in the form of diamond is \ , 

 in that of graphite ^, and in that of charcoal ^, its ordinary amount. 

 These exceptions cannot be explained away; we cannot treble, quad- 

 ruple, nor even double the atomic weight of carbon without incurring 

 great inconveniences." I however advance the following general 

 law as regards this element : — The capacity for heat of the atoms of 

 carbon when of different volumes varies directly as their magnitude^ 

 and does not therefore bear merely a simple relation to the equi- 

 valent. Of course it is well known that the statements of the spe- 

 cific heat of bodies given by different authors vary considerably, as 

 might be expected from the nature of the experiments. If, how- 

 ever, we take the mean of those for the various forms of carbon 

 given in the table at page 241 of Gmehn's Hand-book of Chemistry, 

 we shall find that they agree very nearly with the above statement. 

 The comparison of these means with theory will be seen from the 

 table given farther on, and the existence of the above propounded 

 relation between the volume of the atoms and their capacity for heat 

 will readily be seen ; and this fact, coupled with the close agreement 

 of the specific gravities, I think, proves that the suppositions which 

 have elicited it are correct. 



This relation most probably holds good for all elementary bodies, 

 and if we suppose it to do so, it will, I think, throw some light on 

 the connection between their equivalents and specific heats. It is 

 well known that, in the majority of elements, the equivalent mul- 

 tiplied by the specific heat is a constant quantity. Since, how- 

 ever, as I have shewn above, the capacity for heat varies as the 

 volume of the atoms, it would be necessary for them all to exist in 

 the same relative volumes for this law to hold good universally. The 

 deviations from it, I think fully agree with this supposition. The 

 chief of these are carbon, which, as above described, exists with 

 three different volumes and specific heats, none of which are nor- 

 mal ; — oxygen, which has an abnormal volume and specific heat of 

 ^; — iodine, phosphorus, arsenic, antimony, silver, and gold, which, 

 to judge from their specific heat, have an abnormal volume of 2, 

 and bromine of 3. If the above views be adopted, it will not be 

 necessary to alter their equivalents, as has been suggested by some 

 chemists. 



1 now subjoin a table of the specific gravities, specific heats, and 

 the various distinctive properties of the four species of carbon. 



