Physical AND LITERARY. 337 



yet, after all, mod of them can be 

 brought back to their primitive ftate, and 

 made to exert the fame powers which they 

 did at firft. and again run through all 

 the fucceflive changes ; fo that it may be 

 doubtful whether art can intirely change 

 the nature of fome of thefe folvent li- 

 quors. 



To begin with forae familiar inftances 

 to confirm our remark. Water can dif- 

 folve a certain quantity of any fait ; yet, 

 when it is fully impregnated with one 

 fait, it will ftill difFolve a portion of an- 

 other fait, though not fo much as the 

 fame quantity of pure water would do. 

 From fea water, by evaporation and 

 chryftallization, are procured three di- 

 ftin»5l falts, befides other fubftances, as 

 the ingenious Mr Brown has obferved, 

 viz. the muriatic, or falc for common 

 ufe, the bitter purging fait, and a fiery 

 calcarious fait, different from the other 

 two ; yet fea-water will diffolve, at the 

 fame time, a pretty coniiderable quantity 

 of feveral other falts, as fugar, fait am- 

 moniac, falt-petre and fait qf tartar j and, 

 VoL.L U u after 



