Domestic Encyclopædia (1802)/Coral

CORAL, Corallina, L. a genus of insects, consisting of eight species, which are found in the ocean.

There are, properly, but three kinds of coral, namely, red, white, and black; the last of these is the rarest and most esteemed. When coral is first taken out of the sea, the small protuberances on its surface are soft, and yield on expression a milky juice, which effervesces with acids. The cortical part, or the external coat, is not so compact as the internal, and may easily be separated, while in a fresh state. The greatest traffic in this article is carried on at Genoa and Leghorn.

Coral is not unfrequently imitated, by artificial compositions, so as to resemble the real. But this fraud may be detected, by exposing it to fire; as the counterfeit does not afford the alkaline earth, yielded by the genuine coral. The colouring ingredients employed in preparing the former, are cinnabar and minium, both of which are easily ascertained. The natural coral seems to receive its colour from iron, as spirit of vitriol acquires from it a ferruginous taste; and, on calcination, some particles are discoverable among the ashes, that are attracted by the magnet.

Various unsuccessful attempts have been made to extract a fine colour from red coral, the Isis nobilis, L. by means of spirit of wine. The method of obtaining it is as follows: Dissolve a pound of sugar in a little water, add to it half a pound of wax, then take a pound of coral, and boil them together. Thus, the coral will part with its redness, and remain in other respects unaltered. In order to prepare this tincture, the wax and sugar must be previously dissolved in spirit of wine.