j64 ESSAYS AND OBSERVATIONS 



I had the curiofity to fatisfy myfelf of the 

 purgative power of m^gnefia., and of Boffmim% 

 opinion concerning, it, by the following eafy 

 experiment. I made a neutral fait of magnejia 

 and diftilled vinegar ; choofing this acid a;S 

 being, like that in weak ftomachs, the produdt 

 of fermentation, SijL drams of this I dif- 

 folved in water, and gave to a middle-aged 

 man, defiring him to take it by degrees. 

 After having taken about a third, he defifted, 

 and purged four times in an eafy and gentle 

 manner. A woman of a ftrong conftitution 

 got the remainder as a brifk purgative, and 

 it operated ten times without caufing any un- 

 calinefs. The tafte of this fait is not dif^ 

 agreeable, and it appears to be rather of the 

 cooling than of the acrid kind. 



Having thus given a lliort fketch of the 

 hiflory and medical virtues of magnejia^ \ 

 now proceed to an account of its chemical 

 properties. By my firft experiments, I in- 

 tended to learn what fort of neutral falts 

 might be obtained by joining it to each of 

 the vulgar acids j and the refult was as 

 follows. 



Magnesia is quickly diffolved with vio- 

 lent eifervefcenee, or explofion of air, by the 



acids 



