A Manual of the Chemistry of the Carbon Compounds

THE CHEMISTRY OF
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It is thus seen that the atoms of a polyvalent element have the
property of combining with each other in different proportions. This
property is also possessed by carbon, but in a much greater extent; for
whilst in the case of other elements the number of atoms uniting in
this way is very limited, we find it most characteristic of tetrad carbon,
thai a very large number of atoms can combine with each other
to form groups acting in a great number of reactions like a single
atom.
Bat carbon possesses another peculiarity in common with no othei
element; all tlve units of combining capacity in such a group, which are
not saturated by carbon itself, can be saturated with hydrogen.
Thus, whilst most of the metals do not combine with hydrogen
at all, and the non-metallic elements only form one, two, or at
the most three compounds with hydrogen, we find that there exists
a great number of hydrocarbons, whioh is daily increased by new
discoveries.
1 The hydrocarbons are not only the most simple of the carbon
compounds, but from a theoretical point of view are also the most
important, because all the other carbon compounds can be regarded as
derivatives of them, and as being formed, by hydrogen being replaced
by other elements. Thus a considerable number of compounds found
in nature can be prepared artificially from hydrocarbons, and on the
other hand, as soon as tha constitution of a certain compound is understood,
we are in a position to convert it into the hydrocarbon from
which it has been theoretically derived. In most of these compounds
apart of the hydrogen is replaced by oxygen or by the monad group
Hydroxyl HO, and m others by nitrogen, or the monad group NHg.
However, all the other elements can be artificially introduced into
carbon compounds, but there are only a few cases in whioh all the
hydrogen can be substituted. Thus, the number of carbon chlorides
is very much smaller than that of the hydrocarbons; with, oxygen,
carbon forms only two cpmpounds, the monoxide CO and the dioxide
COa; and with nitrogen it only combines in one proportion to form
cyanogen, CgNj. From this it follows that the great majority of carbon
compounds always contains hydrogen; that there is present ia them a
residue of the original hydrocarbon.
We may therefore define that part of our science which is generally
known as Oi^anic Chemistry as: The Chemistry of tlte Hydrocarbons
and their Derivatives.