Year: 1872

chemist of celebrity in 1871. 1t is found in three
ores-as an oxde in the mineral called wolf
ram, which is tungsate of protoxide of iron,
met with in the tn-mines of Saxony and Bohe-
mia, and in Cornwall; and in tungstate of lime;
called Tungsten, a Swedish word for heavy
stone, in which the metal was originally dis
covered, and it is obtained in the same localities
us the last. Tungsten is grayish white metal,
With specific gravity of 7.5 1t is infusible as
platinum, and has only been obtained in gran
rlar form. The grains are so hard as scarcely to
yield to steel file. The metal has been arti-
tcially combined in alloys, with gold, silver,
copper, iron, lead, tin, antimony bismuth and
manganese; but from the extreme infusbility of
the tungsten the alloys formed with difficulty,
and have not been applied to any useful purpose
i'll the arts.


MERCURY


Has been known from the remotest antiquity,
and its powers of separating the precious metals
from their ores, by amalgamation, have been
made use of from the earliest ages. This metal
is nearly the same color as that of silver; when
perfectly pure its surface is more brilliant than
that metal. The specific gravity of mercury is
1886, which means that, bulk for bulk, it is 10 %
times heavier than water. At temperature of
400, that is 729 below the freezing point of water
as indicated by Fahrenheit's thermometer scale,
mercury becomes solid, or, as is usually termed.
freezes. In that state it is soft and malleable
but it is not safe to touch the contact causing
pain like that from hot iron and the skin is as
quickly destroyed, This is occasioned by the
sudden abstraction of heat


Although mercury is so different in its habits
and properties from all other metals, its uses are
very numerous; and there are few which are
more important both in commerce and the arts


One of the combinations of mercury with chic
rine is the celebrated medicine, calomel and an
other is the highly poisonous substance called
corrosive submate; cinnabar and vermillion are
compou DIS of mercury with sulphur, and are
called sulphurets of mercury. Mercury unites
readily with many, and has strong tendency to
unite with all metals. The compounds it forms
are called amalgams (from a Greek word mean
ing sotten,) because such alloys are soft instead
of hard, like those of other metals The readiness
with which it unites with gold and silver, and
the facility with which it is again separated from
them by heat, renders mercury Of great import





alloys in mining operations. The amalgam
ployed to excite the action of electrical machines
consists of four parts of mercury to one of bis
muth. But more extensive is made of an
amalgam of mercury and tin, in what is called
slvering of mirrors.


The weight and huidty of mercury especially
adapt it to two very mportantpurposes namely,
the construction of the barometer and thcmome-
ter. If fluid be poured into a tube which is
closed at one end, and the other be stopped with
the finger, whilst the tube is being inverted and
its open end be dipped into a vessel containing
the same kind of huid that portion in the tube
will not run out might be expectd but will
remain standing at such height as will exactly
ceunterpose Cor equal in weight column of
air of the whole heighth of the atmosphere, and of
the same diameter as the bore of the tube. Now
as the diameter of the tube remains the same, if
any alteration should take place in the weight of
the column of air, of corresponding dimensions,
the fluid in the tube will rise fall, so to
actly counterbalance the air The changes in
the heghth of the fluid in the tube will therefore
indicate the changes that take place in the weight
or pressure of the atmosphere, and an instrument
which is so constructed as to enable an observer
to mark these changes with accuracy is called a
barometer from the Greek words, meaning
weight and measure. If water were the fluid
employed, the tube must be at least thirty-four
feet long, for it requires column of wuter of
that heighth to balance one of air of an equal
diameter or area of base Bat lloIeuTy is thir-
teen and one half times heavier than water, so
a. ~ Of a1 opl ha
inches long to produce the desired effect at the
usual or average weight of the atmosphere.
Hence, by employing mercury, barometers are
made of a portable size; add to which the metal
is not subject to freeze corrupt as water would
under similar circumstances.


The fuidity of mercury causes it to indicate
changes of temperature by expanding or con-
tractinr perceptibly to the eye, especially if en-
closed in a narrow tube which is hermetlcally
sealed and from which air is perfectly expelled
In this case the expansion contraction of the
metal can take place only i'll the direction OF the
length of the tube, and is therefore very appar-
ent. The thermometer is such an instrument,
and is so called from Greek words meaning heat
and measure. SO essential are these two lnstru-
ments to the prosecution of scientific researches,
that without them little or no progress could
have been made; and we still should have been
in state of comparative ignorance on many sub
iects conneced with natural philosophy, and es-
pecally those relating to meteorology


Excepting for the before mentioned purposes
mercury, in its metallic FORM is not much used
in the arts but its salts and oxides are OF great
Importance in medicine. Illuminating powder
is prepared from mercury, analogous to that
| from platinum, gold and silver. but less 1orm-
1 idahle. especially than that from silver. This
Illuminating mercury is now generally and extern
fire., fire arms, For this purpose it is mixed with
fine gunpowder, since the necessary charge OF the n
| powder, if used alone, would be too small to be
manage able. The proportion of this mixture odS Is
three parts of the mercurial preparation to GUY
of the gunpowder The proper charge is enclosed