XVI. Notice respecting Native Concrete Boracic Acid.
By Smithson Tennant, Esq. F.R.S. &c.
Communicated by L. Horner, Esq. Sec. of the Geological Society.
The Boracic Acid is not found like the greater number of substances
in almost every country, but as far as our present knowledge
extends, appears confined to a few particular places. On this
account, as well as the great utility of borax in various arts, the
discovery of its existence in any new situation may deserve to be
recorded.
Some months ago Mr. Horner was so obliging as to shew me a collection of volcanic productions from the Lipari Islands, presented to the Geological Society by Dr. Saunders. They consisted chiefly of sulphur, and of saline sublimations on the lava, but among these more common substances there were several pieces of a scaly shining appearance, resembling boracic acid. The largest of these had been cut of a rectangular shape, and was about 7 or 8 inches in length, and 5 or 6 in breadth, as if it had been taken from a considerable mass. On one side of most of the pieces was a crust of sulphur, and the scaly part itself was yellower than pure boracic acid. To ascertain if the scaly part was coloured by sulphur, I exposed it to heat in a glass tube, land after the usual quantity of water had come over there sublimed from it about a tenth of its weight of sulphur, and the remainder was pure boracic acid.
