MER 
much larjSier portions are dissolved^ The 
taste of this salt is styptic and disagreeable, 
and it acts as a most virulent poison, so 
that although it is used in medicine, it can- 
not be administered in larger qiiantities 
than the sixth or eighth of a grain. The 
oxide which exists in the corrosive muriate 
of mercury, consists of • 
Mercury 85 
Oxygen — 15 
100 
In the muriate there are 
Oxide 82 
Acid ^ 
100 
Therefore ioo parts of the muriate consist 
of 
Mercury 67 
Oxygen 12.3 
forming eighty-two parts of oxide, with 
which eighteen parts of muriatic acid are 
combined. 
The oxides of mercury are all reduced 
by heat alone, without the addition of any 
combustible substance, and afford oxygen 
gas. Mercury itself dissolves gold, silver, 
tin, and other metals, and if ptopeily com- 
bined with it in sufficient quantity, the mer- 
cury loses its fluidify, and forms an amal- 
gam. It is observed, that a solid amalgam 
of lead, and another of bismuth, have the 
property of becoming fluid. By combinar 
tion with sulphur, mercury affords two com- 
pounds. By long trituration, these bodies 
unite, and form a black sulphuret. ' When 
united by fusion, and afterwards sublimed, 
a red sulphuret is produced, called cinna- 
bar, which, being reduced to powder, af- 
fords the common pigment vermillion. 
Mercury is the basis of a new fulminating 
compound. The oxides precipitated from 
their combinations witli acids, by the alka- 
lies or earths, especially by ammonia or 
lime, are capable, when combined with sul- 
phur, of detonating. If triturated with one- 
sixth part of tlieir weight of sulphur, on be- 
ing exposed gradually to heat they explode 
with considerable force. These materials 
must be prepared and dried in the open air, 
and exposed to the light. Mr. Howard has 
discovered another fulminating powder of 
mercury, possessed of still greater powers. 
This is prepared by dissolving 100 grains 
of mercury in one ounce and a half of nitric 
acid : the solution, when cold, is to be 
poured upon two ounces of alcohol : a mo- 
MER 
derate heat is then to be applied, till an ef- 
fervescence is excited, when a precipitate 
is formed, which is to be immediately col- 
lected on a filter, well washed with distilled 
water, and carefully dried in a heat not 
much exceeding that of a water-bath. From 
100 grains of mercury, between 120 and 
130 grains of dry precipitate are formed. 
This preparation fulminates very strongly. 
If two or three grains only be laid on an 
anvil, and struck smartly with a hammer, it 
explodes with a loud report. Four grains 
will occasion indentation in the hammer 
and anvil. This powder is found to con- 
sist of oxide of mercury, combined with 
oxalic acid and nitrous etherized gas. The 
two latter being produced during its forma- 
tion, by the action of the nitric acid on the 
alcohol. Its explosion and force are sup- 
posed to be owing to the oxygen present 
suddenly combining with the carbon and 
hydrogen, forming watery vapour and car- 
bonic acid : azotic gas is also discharged, 
and much caloric is evolved, so as to volati- 
lize the mercury : to this, the conversion of 
the mercury into vapour, Mr. Howard as- 
cribes its great explosive force. 
We have observed, that mercury unitep 
with many of the metals : from this pro- 
perty it is used to separate gold and silver 
from the substances with which they are 
mixed. It is thus capable of extracting 
the hundred-thousandth part of its weight 
of gold. In gilding and silvering, it is, from 
the same property, the medium of union 
between the gold or silver, and the metal 
on which the operation is performed. 
Hence mercury is of extensive use in the 
arts : its amalgam, with tin, is used in sil- 
vering mirrors, and in electrical experi- 
ments. Its importance in the structure of 
the common barometer is well known ; and 
the uniformity of its expansion at various 
degrees of heat, has shewn it to be the best 
fluid for thermometers. 
Mercury, in astronomy, is a small star 
that emits a very bright white light : though, 
by reason of his always keeping near the, 
sun, he is seldom to be seen ; and when he 
does make his appearance, his motion to- 
wards the sun is so swift, that he can only 
be discerned for a short time. He appears 
a little after sunset, and again a little be- 
fore sunrise. Mercuiy never goes to a 
greater distance from the sun tlian about 
27° 5’ ; so that he is never longer in setting 
after the sun than an hour and fifty mi- 
nutes ; nor does he ever rise sooner than 
one hour and fifty minutes before that In- 
