’ 
i ed Mr. CAvEND! 1s S Experiments on ‘ai mre 
Ait, “and at the famé’ ‘time ‘the quick filver diftils | over in its ‘alee 
tallic form. It is juftly temarked by Dr. Prrsriey, that the’ 
{olution of quickfilver dves -not begin to yield aes 3% 
air till it acquires its red colour. 
~ Mercurius calcinatts appears to bé only quickfilver’ which 
has abforbed dephlogifticated air from the atmofphere during 
its preparation; accordingly, by giving it a fufficient heat, the 
dephlogifticated air is driven off, arid the quickfilver: acquires 
its original form. It feems therefore that mercurius calcinatus 
and red precipitate, though prepared in a différent manner, are 
very nearly the fame thing. | 
From what has been faid it follows, a red precipitate bar 
mercurius calcinatus contain as much phlogifton as the quick- 
filver they are prepated from but yet, as uniting dephlogifti- 
cated air to 4 metal comes to the fame thing as depriving it of 
part of its phlogifton and adding water to it, the quickfilver 
may ftill be confidered as deprived of its phlogifton; but the 
imperfect metals feem not only to abforb dephlogifticated air 
during their calcination, ‘but alfo to be really deprived of part 
of their phlogifton, as they do not acquire their metallic form 
by driving off the dephlogifticated air. 
In procuring dephlogifticated ait from nitre, the acid acts in 
a different manner, as, upon heating the nitre red-hot, the de« 
phlogifticated air rifes mixed with a little nitrous acid, and at the 
fame time the acid remaining in the nitre becomes very much 
phlogifticated ; which fhews that the acid abforbs phlogifton 
from the water in the nitre, and becomes phlogifticated, while 
the water is thereby turned into dephlogifticated air. On dif- 
tilling. 3155 grains of nitre in, an unglazed earthen retort, at 
yielded 256000 grain meafures of dephlogifticated air*, the 
ftandard 
* This is, about eighty-one grain meafures from one grain of nitre; and the 
weight 
