196. ESSAYS anv OBSERVATIONS - 
Two drams of magnefia were reduced, 
by the action of a violent fire, to two feru- 
ples and twelve grains, with which the 
fame procefs was repeated as in the two 
jait experiments; four drams, one feru- 
ple. and two grains of the fame ‘acid 
were required to compleat the folution, 
and no weight was loit in’ the experi- 
ment. _ 
As in the feparation of the volatile from 
the fixed parts of bodies, by means of 
heat, a imall quantity of the latter is ge- 
nerally raifed with the former; fo the air 
~and water, originally contained in the 
magnéfia, and afterwards diflipated by the 
fire, feem to have carried off a fmall part 
of the fixed earth of this fubitance. This 
is probably the reafon, why calcined mag- 
nefia is faturated with a quantity of acid, 
fomewhat lefs than what is required. to 
diffolve it before calcination: And the 
fame may be afligned as one caufe which 
hinders us from reftoring the whole of its 
original weight by folution and precipi- 
tation. 
