Note 43 — Chapter VIII · CARBON AND THE HYDROCARBONS

Direct experiment shows that however CH3X is prepared (where X = for instance Cl, &c.) it is always one and the same substance. If, for example, in CX4, X is gradually replaced by hydrogen until CH3X is produced, or in CH4, the hydrogen by various means is replaced by X, or else, for instance, if CH3X be obtained by the decomposition of more complex compounds, the same product is always obtained.

This was shown in the year 1860, or thereabout, by many methods, and is the fundamental conception of the structure of hydrocarbon compounds. If the atoms of hydrogen in methyl were not absolutely identical in value and position (as they are not, for instance, in CH₃CH₂CH₃ or CH₃CH₂X), then there would be as many different forms of CH₃X as there were diversities in the atoms of hydrogen in CH₄. The scope of this work does not permit of a more detailed account of this matter. It is given in works on organic chemistry.