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The native bitter fait of the coal-mines, purified 
as before related, I have found exa&ly to agree in 
the form of its cryftals, as alfo in its cool bitter tafte, 
its purgative quality, and other properties, with that 
fait which is commonly fold in the fhops, under the 
name of Epfom fait, when this laft named fait 
had been fufficiently purified and reduced into 
larger 'cryftals. This native bitter fait alfo agrees, 
in all its qualities, with a fait (which I extradited from 
the thick and ponderous liquor known by the name 
of bittern) that remains in the falt-pans after the 
common fait is feparated from lea water by codtion. 
It is alfo the fame with the fait of the Scarborough 
waters, as defcribed by Dr. sh aw, which is fold at 
a great price under the name of Scarborough fait. 
Moft of the other purging falts, fold under the 
names of the feveral waters from which they are ex- 
tradited, feem to be the fame with this bitter fait ; 
but differ as they are formed into greater or fmaller 
cryftals, or according to their purity ; there being 
many purging waters which, befides this bitter fait, 
hold common fait, the muriatic calcarious fait, na- 
tron, and other kinds of fait. 
Of the feveral kinds of bitter fait abovementioned 
I have felebted a few fpecimens from thofe which I 
have in my pofteflion. 
Partition IV. N° 5. The common Epfom falts of 
the fhops, purified in the following manner. The 
Epfom fait was diffolved in water, and the lixivium , 
after ftanding fome time, was depurated from a 
large black fcum which arofe to its top, and from a 
dirty fediment ; it was then, by gentle codtion, freed 
from 
