[ 48 1 ] 
XLVIII. A Better from William Brown- 
rigg, M. D . F. R. S. to Sir John Pringle, 
Bart, P. R. S. relating to fome Speci- 
mens of native Salts , colleSled by Dr. 
Brownrigg, and Jhewn at a Meeting of 
the Royal Society , June 23, 1774 *. 
s I R, 
Redde, June 23 >TT BEG leave, through your hands, tor 
IJ74 * J|_ convey to the Royal Society, fpe- 
cimens of various falts, which I have found native 
in the coal-mines near Whitehaven; and which, I 
flatter myfelf, may be of fome ufe in aflifting us to 
form a right judgement concerning the generation of 
thefe falts, and the various ingredients that enter 
their compofition. 
The firfl: of thofe native falts which I offer to the 
Royal Society, is the J'al catharticus amarus, or the 
bitter fait ; which, though it was only firfl: difco- 
vered by Dr. grew in the Epfom waters fo lately as 
towards the clofe of the laft century, is found in 
more abundance, and more univerfally diffufed 
over this globe than any other fait, the common fait 
* Thefe fpecimens were afterwards depofited in the Britifh 
Mufeum. s. horsley, 
Vol. LXIV, Q q (j excepted. 
