XVI. Notice respecting Native Concrete Boraclc Add. 



By Smithson Tennant, Esq. F.R.S. &c. 



Communicaied hij L. Horner, Esq. Sec. of the Geological Socieli/. 



i HE Boracic Acid is not found like the greater number of sub- 

 stances in almost every country, but as far as our present know- 

 ledge 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 ascer- 

 tain if the scaly part was coloured by sulphur, I exposed it to heat in 

 a glass tube, and 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. 



