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Transactions of the Geological Society, 1st series, vol. 1/On Native Boracic Acid




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.

Mr. Horner afterwards informed me, that the late Dr. Menish of Chelmsford had presented to the Geological Society a specimen which he had received, with some other volcanic productions, from Sicily, but which had been collected in the Lipari Islands; the box containing them being marked “ Produziani Volcaniche Raccolte nelle Isole Eolie da Gius Lazzari—Lipari.” He found it to consist of boracic acid, and it perfectly resembled that I have just described, having the same yellow colour from an admixture of sulphur, and a similar crust of this substance adhering to one side.

Any future traveller visiting those countries would do well to examine them with a view to this particular object. The boracic acid may be a more extensive volcanic product than has hitherto been imagined; for in the account given of its discovery some years ago by Messrs. Hoëfer and Mascagni, near Monte Rotando, to the west of Sienna, we can have no doubt of its volcanic origin in those places, from the substances which are there described to accompany it.