C 57 ] 
VIII. Some Account of a Salt found on the 
Pic ^TenerifFe, by W. Heberden, M. D. 
F. R. S. 
Read Feb. 7, v ]SJ the account of a journey up the Pic 
jI. of Teneriffe, by Dr. Thomas Heberden, 
printed in the Philofoph. Tranfadions, Vol. XLVII. 
N° 57. there is mention made of a fort of fait, as 
well as of brimftone, with which fome parts of the 
Pic are covered. There is no difficulty in conceiving 
how brimflone may be forced up by fubterraneous 
hres; and it is no uncommon thing to find it in other 
places : but it is not fo eafy to underfiand how a fait 
of fo fixed a nature, as this is, ffiould be fublimed 
to fuch a height without being cooled and fixed long 
before it arrives at the furface of the earth, where no 
fenfible heat is perceived. Neither am T able to ex- 
plain, how it happens, that a fubftance, fo eafily 
melted in water, is not difiblved and wafhed away, 
as fafi; as it can be produced, by the dews, and rains, 
and melted fnow. 
By means of my brother Dr. Thomas Heberden, 
I have procured a parcel of this fait collected from 
the Pic, a fpecimen of which, together with fome 
of the fulphur, is here prefented to the Society ; 
both which, though fo very pure, are juft 2,s they 
were taken up. My brother informs me, that the 
fait is found not far from the verge of the crater, and 
that it is called, by the Spanilli inhabitants of the 
Vol. LV. I ^ ifland, 
