The valuable constituents
actually extracted are then these: benzene, toluene, xylene,
naphthalene, anthracene, and phenol or carbolic acid. One ton of
Lancashire coal, when distilled in gas retorts, yields about 12 gallons
of coal-tar. Let us now learn what those 12 gallons of tar will give us
in the shape of hydrocarbons and carbolic acid, mentioned as extracted
profitably from tar. This is shown very clearly in the following table
(Table A).
The 12 gallons of tar yield 1-1/10 lb. of benzene, 9/10 lb. of toluene,
1-1/2 lb. of carbolic acid, between 1/10 and 2/10 lb. of xylene, 6-1/2
lb. of naphthalene, and 1/2 lb. of anthracene, whilst the quantity of
pitch left behind is 69-1/2 lb. But our table shows us more; it
indicates to us what the steps are from each raw material to each
colouring matter, as well as showing us each colouring matter. We see
here that our benzene yields us an equal weight of aniline, and the
toluene (9/10 lb.) about 3/4 lb. of toluidine, the mixture giving, on
oxidation, between 1/2 and 3/4 lb of Magenta.
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