EMILY.
It is, I suppose, the earthly, the metallic, and the saline parts of coals, that compose the cinders or fixed products of their combustion; whilst the hydrogen and carbon, which they derive from vegetables, constitute their volatile products.
CAROLINE.
Pray is not coke, (which I have heard is much used in some manufactures,) also a bituminous substance?
MRS. B.
No; it is a kind of fuel artificially prepared from coals. It consists of coals reduced to a substance analogous to charcoal, by the evaporation of their bituminous parts. Coke, therefore, is composed of carbon, with some earthy and saline ingredients.
Succin, or yellow amber, is a bitumen which the ancients called electrum, from whence the word electricity is derived, as that substance is peculiarly, and was once supposed to be exclusively, electric. It is found either deeply buried in the bowels of the earth, or floating on the sea, and is supposed to be a resinous body which has been acted on by sulphuric acid, as its analysis shows it to consist of ah oil and an acid. The oil is called oil of amber, the acid the succinic.
EMILY.
That oil I have sometimes used in painting, as it is reckoned to change less than the other kinds of oils.
MRS. B.