M E It 
M E f. 
M E R 
the oxide of mercury and sulphur. But the 
experiments of Proust have demonstrated 
that the mercury which it contains is in the 
metallic state. According to that very ac- 
curate chemist, it is composed of 85 parts of 
mercury and 15 of sulphur. It is therefore 
I suiphuret of mercitry. 
The suiphuret of mercury has a scarlet co- 
i lour, more or less beautiful, according to the 
mode of preparing it. Its specific gravity is 
about 10. It is tasteless, insoluble in water, 
add in muriatic acid, and not altered by ex- 
; posure to the air. When heated sufficiently, 
it takes fire, and burns with a blue flame. 
When mixed with half its weight of iron 
j filings, and distilled in a stone-ware retort, 
I the sulphur combii*'S with the iron, and the 
j mercury passes into the receiver, which 
ought to contain water. By this process 
mercury may be obtained in a state of purity. 
The use of suiphuret of mercury as a paint is 
well known. 
Mr. Pelletier, after several unsuccessful 
| attempts to combine phosphorus and mer- 
cury, at last succeeded by distilling a mix- 
; ture of red oxide of mercury and phosphorus. 
Part of the phosphorus combined with the 
I oxygen of the oxide, and was converted into 
an acid; the rest combined with the mercury, 
lie observed that the mercury was converted 
| into a black powder before it combined with 
the phosphorus. As Pelletier could not suc- 
, ceed in his attempts to combine phosphorus 
; with mercury in its metallic state, we must 
conclude that it is not with mercury, but with 
the black oxide of mercury, that the phos- 
phorus combines. The compound, there- 
fore, is not phosphorus of mercury, but black 
phosphuretecl oxide of mercury. 
It is of a black colour, of a pretty solid 
consistence, and capable of being cut with a 
knife. When exposed to the air, it exhales 
vapours of phosphorus. 
Mercury does not combine with the simple 
incombustibles. 
Mercury combines with the greater num- 
ber of metals. These combinations are known 
in chemistry by the name of amalgams. 
The amalgam of gold is formed very rea- 
dily, because there is a very strong affinity 
between the two metals. If a bit of gold is . 
dipped into mercury, its surface, by com- 
bining with mercury, becomes as white as 
silver. The easiest way of forming this 
amalgram is to throw small pieces of red-hot 
gold into mercury. The proportions of the 
ingredients are not determinable, because 
the amalgam has an affinity both for the gold 
and the mercury; in consequence of which 
they combine in any proportion. This amal- 
gam is white, with a shade of yellow ; and 
when composed of six parts of mercury and 
one of gold, it may be obtained crystallized 
in four-sided prisms. It melts at a moderate 
temperature ; and when heated sufficiently, 
the mercury evaporates, and leaves the gold in 
a state of purity. It is much used in gilding. 
The amalgam composed of ten parts of mer- 
cury and one of gold, is spread upon the metal 
which is to be gilt ; and then, by the applica- 
tion of a gentle and equal heat, the mercury 
is driven off, and the gold left adhering to the 
metallic surface; this surface is then rubbed 
with a brass-wire brush under water, and af- 
terwards burnished. 
Dr. I ewis attempted to form an amalgam 
©f platinum, but hardly succeeded after a 
VOL. II. 
labour which lasted for several weeks. Guy- 
ton Morveau succeeded by means of heat, 
lie fixed a small cylinder of platinum at the 
bottom of a tall glass vessel, and covered it 
with mercury. The vessel was then placed 
in a sand-bath, and the mercury kept con- 
stantly beiling. The mercury gradually 
combined with the platinum ; the weight of 
the cylinder was doubled, and it became 
brittle. W hen heated strongly, the mercury 
evaporated, and left the platinum partly oxi- 
dated. It is remarkable, that the platinum, 
notwithstanding its superior specific gravity, 
always swam upon the surface of the mercu- 
ry, so that Morveau was under the necessity 
of fixing it down. 
The amalgam of silver is made in the same 
manner as that of geld, and with equal ease. 
It forms dentritical crystals, which, according 
to the Dijon academicians, contain eight 
parts of mercury and one of silver. It is of a 
white colour, and is always of a soft consist- 
ence. Its specific gravity is greater than the 
mean of the two metals. Gellert has even 
remarked that, when thrown into pure mer- 
cury, it sinks to the bottom of that liquid. 
When heated sufficiently, the mercury is 
volatilized, and the silver remains behind 
pure. 
The affinities of mercury as ascertained by 
Morveau, and of its oxides as exhibited by 
Bergman, are in the following order: 
Mercury. Oxide of Mercury. 
Muriatic acid. 
Oxalic, 
Succinic, 
Arsenic, 
Phosphoric, 
Sulphuric, 
Saclactic, 
Tartaric, 
Citric, 
Sulphurous, 
Nitric, 
Fluoric, 
Acetic, 
Boracic, 
Prussic, 
Carbonic. 
Mercury*, in astronomy, the smallest 
of the planets, and the nearest the sun. See 
Astronomy. 
MERGUS, in ornithology, a genus of 
birds of the order of anseres; distinguished 
by having the beak of a cylindrical figure, 
and hooked at the extremities, and its denti- 
culations of a subulated form. 
1. The cucullatus, or crested diver of Ca- 
tesby, has a globular crest, white on each 
side ; and the body is brown above, and white 
below. This elegant species inhabits North 
America. It appears at Pludson’s-bay the end 
of May, and builds close to the lakes. The 
nest is composed of grass, lined with feathers 
from the breast; the number of eggs from 
four to six. The young are yellow, and are 
fit to ily in July. They all depart from 
thence in autumn. They appear at New 
York, and other parts, as low as Virginia and 
Carolina, in November, where they fre- 
quent fresh waters. They return to the 
north in March, and are called at Hudson’s- 
bay omiska sheep. See Plate Nat. Hist. fir. 
265. 
2. The merganser, or goosander, weighs 
four pounds ; its length is two feet four inches; 
X 
Gold, 
Silver, 
Tin, 
Lead, 
Bismuth, 
Platinum, 
Zinc, 
Copper, 
Antimony, 
Arsenic, 
Iron. 
m 
the breadth three feet four. The dun-diver, 
or female, is less- than the male ;• the head and 
upper part of the neck are ferruginous ; the 
threat- white; the feathers on the hind part 
are’ long, and form a pendant crest ; the 
back, the coverts of the wings, and the tail, 
are of a deep ash-colour; the greater quill- 
feathers are black, the lesser white; the 
breast and middle of, the belly , are white, 
tinged with yellow. The goosander seems to 
prefer the more northern situations to thos® 
of the south, not being seen in the last ex- 
cept in very severe seasons. It continues 
the whole year in the Orkneys; and has 
been shot in the Hebrides in summer. It is 
common on the continent of Europe and 
Asia, but most so towards the north. 
3. The albellus, or smew, weighs about 34 
; ounces ; the length is 18 inches, the breadth 
26 ; the bill is near two inches long, and of a 
lead-colour; the head is adorned with a long 
crest, white above and black beneath; the 
head, neck, and whole under part of the 
body, are of a pure white ; the tail is of a deep 
ash-colour, the legs a blueish grey. The fe- 
male, or lough-diver, is less than the male ; 
the back, the scapulars, and the tail, are 
dusky; the belly is white. The smew is seen 
in England only in winter, at which season it 
will sometimes be met with at the southern 
parts of it ; as also in France, in the neigh- 
bourhood of Picardy, where it is called la 
piette: similar to this, we have heard it called 
in Kent by the name of magpie-diver. 
There are three other species. . 
MERIDIAN. See Astronomy, and Ge- 
ography. 
MERIDIONAL PARIS, MILES, or 
MINUTES, in navigation, are the parts by 
which the meridians in Mr. Wright’s chart 
(commonly though falsely called Mercator’s) 
increase as the parallels of latitude de- 
crease : and as the cosine of the latitude of 
any place is equal to the radius or semi-dia- 
meter of that parallel, therefore, in the true 
sea-chart, or nautical planisphere, this radius 
being the radius of the equinoctial, or whole 
sine of 90°, the meridional parts at each de- 
gree of latitude must increase, as the secants 
of the arch, contained between that latitude 
and the equinoctial, do decrease. - The 
tables therefore of meridional parts, which 
we have in books of navigation, are made by 
a continual addition of secants ; they are cal- 
culated in some books for every degree and 
minute of latitude ; and they will serve either 
to make or graduate a Mercator’s chart, or 
to work the Mercator’s sailing. To use them, 
you must enter the table with the degree of 
latitude at the head, and the minute on the 
first column towards the left hand, and in the 
angle of meeting you will have -the meridio- 
nal parts. Having the latitudes of two places, 
to find the meridional miles or minutes be- 
tween them : Consider whether one of the 
places lies on the equator, or both on the 
same side of it; or, lastly, on different sides. 
1. If one of the proposed places lies on the 
equator, then the meridional difference of la- 
titude is the same with the latitude of the 
other place, taken from the table of meri- 
dional parts. 2. If the two proposed places 
be on the same side of the equator, then the 
meridional difference of latitude is found by 
subtracting the meridional’ parts answering to 
the least latitude, from those answering to the 
