954 PRINCIPLES OF CHEMISTRY 



at a high temperature. Rousseau, for the same purpose, heated 

 carbide of calcium in the electric furnace. There is no doubt that 

 all these investigators obtained the diamond as a transparent body, 

 which burnt into CO.,, and possessed an exceptional hardness, but only 

 in the form of a fine powder 



Judging from the fact that carbon forms a number of gaseous bodies 

 (carbonic oxide, carbonic anhydride, methane, ethylene, acetylene, <fec.) 

 and volatile substances (for example, many hydrocarbons and their 

 most simple derivatives), and considering that the atomic weight of 

 carbon, C=12, approaches that of nitrogen, - N= 14, and that of oxygen, 

 O= 1 6, and that the compounds CO (carbonic oxide) and N 2 C ? (cyanogen) 

 are gases, it may be argued that if carbon formed the molecule C 2 , like 

 No and O 2 , it would be a gas. And as'through polymerism or the com- 

 bination of like molecules (as O 2 passes into O 3 or NO 2 into N 2 O 4 ) the 

 temperatures of ebullition and fusion rise (which is particularly clearly 

 proved with the hydrocarbons of the C n H 2n series), it ought to be con- 

 sidered that the molecules of charcoal, graphite, and the diamond are 

 very complex, seeing that they are insoluble, non- volatile, and infusible. 

 The aptitude which the atoms of carbon show for combining together 

 and forming complex molecules appears in all carbon, compounds. 

 Among the volatile compounds of carbon many are well known the 

 molecules of which contain C 5 . . . C 10 . . . C 20 . . . C 30 , &c., in 

 general C n , where n may be very large, and in none of the other ele- 

 ments is this faculty of complexity so developed as in carbon. 18 Up 

 to the present time there are no grounds for determining the degree 

 of polymerism of the charcoal, graphite, or diamond molecules, and it 

 can only be supposed that they contain C, t where n is a large quantity. 

 Charcoal and those complex non-volatile organic substances which 

 represent the gradual transitions to charcoal 19 and form the principal 



formed on the surface and prevented the metal expanding, and so produced a powerful 

 pressure. A portion of the carbon which separates out under these, conditions exhibits 

 the properties of the diamond. 



18 The existence of a molecule S 6 is known (up to 600), and it must be held that this 

 accounts for the formation of hydrogen persulphide, H 2 S 5 . Phosphorus appears in the 

 molecule P 4 and gives P 4 H 2 . When expounding the data on specific heat we shall have 

 occasion to return to the question of the complexity of the carbon molecule. 



19 The hydrocarbons poor "in hydrogen and containing many atoms of carbon, like 

 chrysene and carbopetrocene, &c., C n H 2 (n-n;, are ^solids, and less fusible as n and m 

 increase. They present a marked approach to the properties of the diamond. And in 

 proportion to the diminution of the water in the carbohydrates C n H 2TO O TO for example 

 in the humic compounds (Note 5) the transition of complex organic substances to 

 charcoal is very evident. That residue resembling charcoal and graphite which is 

 obtained by the separation (by means of copper sulphate and sodium chloride) of iron 

 from white cast-iron containing carbon chemically combined with the iron, also seems, 

 especially after the researches of G. A. Zaboudsky, to be a complex substance containing 



