PHYSICAL AND LITERARY. i6e 



it is prepared, and have therefore been 

 obliged to make my experiments upon the 

 fecond. 



In order to prepare it, I at firft employed 

 the bitter faline liquDr called bittei-n^ which 

 remains in the pans after the evaporation of 

 fea water* But as that liquor is not always 

 eafily procured, I afterwards made ufe of a 

 fait called epfom-Jalt^ which is feparated from 

 the bittern by cryftallization, and is evidently 

 compofed of magnefia and the vitriolic acid. 



There is like wile a fpurious kind of 

 Glauber fait, which yields plenty di magnefia, 

 and feems to be no other than the epfo'm fait 

 of fea water reduced to cryftals of a largef 

 fize. And common fait alfo affords a fmall 

 quantity of this powder ; becaufe being fepa- 

 rated from the bittern by one hafty cryftalli- 

 zation only, it neceffarily contains a portion 

 of that liquor. 



Those who would prepare a «;^|-;??/7i7 from 

 epfom-falt, may ufe the follov^^ing procefs. 



Dissolve equal quantities of epfom-falt* 

 and of pearl alhes feparately in a fufficient 

 quantity of water ; purify each folution from 

 its dregs, and mix them accurately together 



Vol. IL X by 



