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These specific heats are not from my experiments, but are 
the mean of those given in Gmelin's Hand-book of Che- 
mistry ; and though they differ considerably from theory, yet 
to any one acquainted with the nature of the experiments, 
and the usual great difference, as determined by various 
authors, it will not appear anything more than what might 
result from errors of observation. 
If we take into consideration only the specific gravities, 
this law is not at all apparent; for, as I have shown, the 
specific gravity is not a simple function of the volume of the 
atoms, but a compound one of it and of the crystalline form 
and arrangement of the particles ; whereas the specific heat 
is a simple function of the volume, and is in no way related 
to the crystalline form. So far as I am aware, this impor- 
tant distinction has been overlooked in discussing the relative 
specific gravities of various bodies. 
Gmelin, in his Hand-book of Chemistry, in mentioning 
the relation of the specific heats of the various forms of 
carbon, says — " The capacity for heat of carbon in the form 
of diamond is one-fourth, in that of graphite one-third, and 
in that of charcoal one-half the ordinary amount. These 
exceptions cannot be explained away ; we cannot triple, 
quadruple, nor even double the atomic weight of carbon 
without incurring great inconvenience." I, however, think 
that, from what I have shown to be the case in carbon, 
chemists will not insist on a constant, perfectly simple ratio 
between the specific heat and atomic weight of elementary 
bodies, since they may exist in different relative volumes, and 
thus much modify the relation of their specific heats. 
The properties of these four species of carbon, as is well 
known, vary very remarkably, and it may, perhaps, be well 
to mention some of the leading differences between them. 
In the first place, the distinction between diamond and 
charcoal is very great, and has long been a subject which 
