ON THE ALLOTROPY OF THE ELEMENTARY BODIES. 241 
subsequently became acquainted with dissimilar conditions of the 
same kind in silicium, phosphorus, and finally (as Frankenheim 
proved in 1839 by ingenious experiments*) in sulphur. To ex- 
press these dissimilar conditions in writing, he proposed annex- 
ing the letters «, 8, y to the symbols of the elements. Although 
Frankenheim made no distinction between the isomerism of com- 
pound bodies and the dissimilarity of the condition of the ele- 
ments which he included under the same name, isomerism, still 
the first clear notion of it is put forth in the researches we have 
mentioned. I shall endeavour to extend this a little further, 
and I now pass on to the consideration of the relation of the 
different elements according to this view. 
Carbon appears to occur in three different allotropic states, 
viz, as— 
1. Charcoal, which I shall distinguish by C.. It is character- 
ized by its ready inflammability, its property of being completely 
consumed in the air at the temperature generated by its com- 
bustion, and lastly by its greater specific heat, which amounts 
to 0°24. It may justly be urged against the view that charcoal 
is an allotropic modification of the element carbon, that it usually 
contains hydrogen. However, that this does not amount to more 
than what may be regarded as accidental, arising from the mode 
of its preparation, is evident from the fact that it can be ex- 
pelled, either by heating it to low redness in a current of chlo- 
rine, or by retaining it at a low red heat exposed to the air, 
without its being converted into the next modification, which 
however is effected by exposing it for some time to an intense 
red heat. There is still another method by which the carbon 
may be transformed into this allotropic condition, that is, by 
decomposing carbonate of potash or soda with potassium at a 
gentle heat, dissolving the saline mass in water and washing out 
the carbon. This carbon is still more combustible than char- 
coal, and burng still more vividly than the latter when in the form 
of powder. 
2. Graphite, C,, with its well-known varieties, anthracite, coke, 
fossil coal, &c. 
3. Diamond, Cy.—Both these are characterized by their difti- 
culty of combustion. The diamond crystallizes in forms of the 
regular cubic system, is colourless, transparent, and almost the 
hardest body known. Graphite is obtained in a crystalline state 
* Journ. fiir Prakt. Chemie, vol. xvi. p. 1. 
