390 ESSAYS anp OBSERVATIONS 
fome hours, it does not make any the leaft 
change in the water. ‘The magnefia, when 
dried, is found to have gained ten grains ; 
but it neither effervefces with acids, nor 
does it fenfibly affect lime-water, 
OBSERVING magnefia to lofe fach a re- 
markable proportion of its weight in the 
fire, my next attempts were directed to the 
inveftigation of this volatile part, and, a- 
- mong other experiments, the following ~ 
‘feemed to throw fome light upon it. 
THREE ounces of magnefia were diftilled 
‘in a glafs retort and receiver, the fire bé- 
ing gradually increafed until the magnefia 
-was obfcurely red hot. When all was 
cool, I found only five drams of a whitifh 
water in the receiver, which had a faint 
fmell of the fpirit of hartfhorn, gave a 
green colour to the juice of violets, and 
rendered the folutions of corrofive fubli- 
mate and of tilver very flightly turbid. 
But it did not fenfibly eflervefce ‘with a- 
cids. 
Tue magnefia, when taken out of the re- 
tort, weighed an ounce, three drams, and 
thirty grains, or had loft more than the 
half 
vf 
