716 ,DR A. CRUM BROWN ON ISOMERIC COMPOUNDS. 



ponents, one depending on the structure of the molecule, and the position of the 

 equivalents in question in it, and the other independent of these. For con- 

 venience we may call the first the molecular, and the second the atomic 

 component.* 



From all that we know of the disturbing effect of an equivalent on the rela- 

 tions of the other equivalents in the molecule, we may safely assume that the 

 molecular component of the force uniting the two carbon atoms to form the hex- 

 atomic carbon radical (Cg)^^', is not the same in any two compounds. And if 

 there be more than one body having the formula C.^Hy, we are forced to the con- 

 clusion, that in these cases at least, the atomic component is different also. 



The question in reference to the second assumption mentioned above may now 

 be stated thus, — Does the atomic component of the force uniting the two carbon 

 atoms remain the same through such a series of transformations as that connect- 

 ing acetonitrile and hydride of ethyl ? There is every reason to suppose that it 

 does, if it is always the same for the same pair of equivalents ; for there is 

 nothing in any of these transformations which would lead us to suppose that one 

 carbon equivalent has changed places with another. We are then brought to the 

 dilemma, either methyl gas and hydride of ethyl are identical, or a change takes 

 place in the atomic component of the force uniting the two carbon atoms in some 

 of the transformations connecting cyanogen gas and hydride of ethyl. 



' In connection with this, it may be proper to examine shortly the relation 

 between the view of the chemical nature of carbon provisionally adopted by 

 BuTLERovv, in the paper referred to above, and that of Kolbe, as explained in his 

 " Lehrbuch der Organischen Chemie," and in several valuable papers in Liebig's 

 " Annalen," and in Erlenmeyer's " Zeitschrift." 



Professor Kolbe considers carbon (carbonyl = (CJ, C—Q) as a tetratomic 

 element (as indeed it is now admitted by every one to be), and holds that in a large 

 number of organic compounds, the four equivalents united to the carbonyl atom 

 may be divided into two groups, — the intra-radical and the extra-radical, — so far 

 his view resembles that of Butlerow ; but it differs from it in the following 

 respects : — Butlerow assumes that it is an essential property of the carbon atom 

 to combine in this way, that carbon always combines with two equivalents in one 

 way, and with two others in another way. Kolbe only admits this in the case 

 of bodies derived from dibasic carbonic acid. In methylic compounds, for in- 

 stance, he regards the three atoms of hydrogen as precisely similar. When we 

 examine the theories more closely, we see another reason to doubt their identity. 

 If we try to compare them, we find it difficult to decide whether Butlerow's 



* The terra component is, of course, not used here in its strictly dynamical sense, what is 

 meant is, that the total force uniting a pair of equivalents, is a function of two quantities, the one 

 depending on the structure of the molecule, and the position in it of the two equivalents, and the 

 other on the chemical nature of the two equivalents. 



