J7P ESSAYS AND OBSERVATIONS 



yields a white powder, the largeft portion of 

 which is a true magnejia. 



From this experiment it appears, that an 

 acid quits a calcarious earth to join itfelf to 

 maghefia j but the exchange being performed 

 flowly, feme of the magnefia is ftill un- 

 dilTolved, and part of the calcarious earth 

 remains yet joined to the acid. 



When a fmall quantity of magnefia is 

 thrown into a folution of the corrofive fubli- 

 inate of mercjufy, it foon feparates part of the 

 mercury in the form of a dark red powder, 

 and is itfelf diffolved. 



Imagining that I perceived fome refem- 

 blance between the properties of magnefia 

 and thofe of alkalis, I was led to try what 

 change this fubftance would fuffer from: the 

 addition of quick-lime, which alters in fuch a 

 peculiar manner the alkaline falts. 



Twenty feven grains of magnejia in fine 

 powder were mixed with eighteen ounces of 

 lime-water in a flafk, which was corked clofc 

 and fhaken frequently for four days. During 

 this time, I frequently dipp'd into it little 

 bits of paper i which were coloured with the 

 juice of. violets.; and thefe became green as 

 foon as they touched the water, until the 



fourth 



