A Manual of the Chemistry of the Carbon Compounds

36 THE CHEMISTRY OF
By comparing tlie specific volume of different liquids, the following
laws have been found:—
(1) The difference of CHS in homologous series corresponds to a
difference of 22 in the specific volume :—
Formic Acid . .
Acetic Acid . .
Propionic Acid .
Butyric Acid . .
Valeric Acid . .
Molecular
Weight.
. . 46 . .
. . 60 . .
. . 74 . .
. . 88 . .
. . 102 . .
Specific
Volume.
. 42
. 64
. 86
. 108
. 130
Difference.
'. 22
. 22
. 22
. 22
From this it follows that the group CH2 has the specific volume 22.
(2) Compounds containing as many times two atoms of hydrogen
less, as others contain one atom of carbon more, have the same specific
volume or the specific volume of one atom of carbon is equal to that
of two atoms of hydrogen:—
Molecular Specific
Weight. Volume.
Cymene
Octane C8H,8 Cl0Hu.
. .
.
.
.
. 134
114
. . . . 187
187
Ethyl Ether C.H.OO . . . 74 . . . . 1068
Phenol C6H8O . . . 94 . . . . 1068
Now as the specific volume of CH2 is 22, and that; of hydrogen
half that of carbon, it follows that the specific volume of carbon is 11,
and that of hydrogen 5 - 5.
(3) I8omeric and metamerie compounds have generally the same
speoific volume; amongst the exceptions we find a number of oxygen
compounds. Whilst, therefore, the specific volumes of carbon and
hydrogen remain the same, that of oxygen varies. Thm variation
depends on the manner in which the oxygen is combined with the
carbon. When one atom of oxygen is linked to the carbon atom hy
one combining unit only, its specific volume is 78 ; but when combined
to carbon by both units its specific volume becomes 122. The
specific volume of dyad sulphur varies also: when united with one
combining unit it is 23, but when with both it is 28-6.
The specific volume of nitrogen in the amines is 2*3, in cyanogen
compounds 17, and in nitroxyl NO417"4 The specific volumes of the
monad elemeuts of the chlorine group do not exhibit such variations.
They are Cl = 228. Br = 278. 1=37-5.
By means of these numbers the specific gravity of a liquid carbon
compound can easily be calculated. The following table shows how
near these calculated numbers agree with those deduced from the
specific gravity:—