NATURAL 
accafion was a glafs globe, having a 
tube annexed to it, that the quan- 
tity of the fixed air might be more 
accurately meafured. After as 
much quickfilver had been poured 
into ,the glafs globe containing the 
calcareous precipitate as was necef- 
fary to fill it, it was inverted in a 
veffel of the fame fiuid. Some ma- 
rine acid being thea made to pafs 
up into it, the fixed air was expel- 
Jed from the calcareousearth; and, 
in this experiment, in which two 
grains and a half of diamonds had 
been employed, occupied the {pace 
of little more than 10.1 ounces of 
water. 
The temperature of the room, 
when the air was meafured, was at 
55°, and the barometer ftood at 
about 29.8 inches. 
From another experiment, made 
ina fimilar manner, with one grain 
and a half of diamonds, the air which 
was obtained occupied the {pace of 
6.18 ounces of water; according 
to which proportion, the bulk of 
the fixed air from two grains and a 
half would have been equal to 10.3 
ounces. 
The quantity of fixed air which 
was thus produced by the diamond, 
does not differ much from that 
which, according to M. Lavoifier, 
might be obtained from an equal 
weight of charcoal. In the me- 
moirs of the French Academy of 
Sciences for the year 1781, he has 
related the various experiments 
which he made to afcertain the 
oportion of charcoal and oxygen 
in fixed air. From thofe which he 
confidered as moft accurate, he con- 
cluded, that 100 parts of fixed air 
contain nearly 28 parts of charcoal, 
and 72 of oxygen. He eftimates 
the weight of a cubic inch of fixed 
air, under the preffure and in the 
HISTORY. 39% 
temperature above mentioned, to 
be 695 parts of a grain. If we re- 
duce the French weights and mea- 
fures to Englifh, and then compute » 
how much fixed air, according to 
this proportion, two grains and a 
half of charcoal would produce, we 
fhall find that it ought to occupy 
very nearly the bulk of 10 ouncg¢s: - 
of water. 
M. Lavoifier feems to have 
thought that the aérial fluid, pro- 
duced by the combuftion of the 
diamond, was not fo foluble in wa- 
ter as that procured from calcareous 
fubftances. From its refemblance, 
however, in various properties; 
hardly any doubt could remain that 
it confifted of the fame ingredients; 
and I found, upon combining it 
with lime, and expofing it to heat 
with phofphorus, that it afforded 
charcoal, in the fame manner as any 
other calcareous fubftance. 
On the Aion of Nitre upon Gold and 
Platina. By the fame. 
From the Philofophical Tranfactions of 
the Royal Society of London. 
OLD, which cannot be cal- 
J cined by expofure to heat 
and air, has been alfo confidered as 
incapable of being affected by nitre. 
But, in the courfe of fome experi- 
ments on the diamond, an account 
of which has been eommunicated 
to the Royal Society, 1 obferved, 
that when nitre was heated in a tube 
of gold, and the diamond was not 
in fufficient quantity to fupply the 
alkali of the nitre with fixed air, a 
part of the gold was diflolved. From 
this obfervation, I was induced to 
examine more particularly the ac- 
tion of nitre upon gold, as well as 
to enquire whether it would pro- 
Bb4 duce 
