Amalgam.
(a) A combination or alloy in which one of the constituents is mercury.
Usually the term is applied to an alloy of a single metal with mercury.
Some metals readily form amalgams; such metals are: Gold, zinc, silver,
lead and others; some, such as platinum and iron, form amalgams only
under exceptional circumstances.
(b) The word is also applied to compositions for application to the
cushions of frictional electric machine in which cases it is often a
misnomer. True amalgams used for this purpose are made as follows:
(a) Tin, 1 part; Zinc, 1 part; Mercury, 2 parts (Kienmayer).
(b) Tin, 2 parts; Zinc, 3 parts.
(c) Tin, 3 parts; Zinc, 5 parts; Mercury, 4 parts.
(d) Zinc, 1 part: Mercury, 4 parts; Mercury, 9 parts. [sic]
The tin, if such is used, (formula a, b and c) is first melted, the zinc
is added in successive portions. The mercury, which must be heated, is
slowly poured into the melted alloy after removal of the latter from the
fire, and the mixture, while making, is constantly stirred. It is kept
stirred or rubbed in a mortar until cold. Sometimes it is poured into
water and kept in constant agitation until cold. It is thus obtained in
a granular condition, and is pounded in a mortar until reduced to
powder. It must be dried and kept in tightly stopped bottles and is
applied to the cushions after they have been greased. It is to be
noticed that it is said that alloy (d) requires no pulverization beyond
constant rubbing in a mortar as it cools. Sometimes the amalgam is
shaken about in a wooden tray with chalk while cooling. The action of
amalgams is not very clearly understood. Some claim that there is a
chemical action, others that they simply act as conductors, others that
they are more highly negative to the glass than the leather of the
cushions.
Graphite or sulphide of tin (mosaic gold) are sometimes used to coat the
cushions; it is these that are sometimes incorrectly called amalgams.
Amalgamation.
The application of mercury to a metal with which it forms an amalgam, or
with which it amalgamates. Battery zincs are amalgamated in two ways. In
the immersion method, the plate is dipped into an acid solution of
mercuric chloride or nitrate. The latter is best. In the direct
application method the plate is first wet all over with dilute acid and
a little mercury is dropped upon it and is rubbed over the surface with
a rag or, what is better, with a piece of galvanized iron. A very little
mercury answers the purpose. The whole surface of the plate should be
left as bright as silver. (See Action, Local.)
Amber.
Amber is a fossil resin, supposed to be a product of the extinct Pinites
Succinifer and other coniferous trees. Most of it is gathered on the
shores of the Baltic between Koenigsberg and Memel. It is also found in
small pieces at Gay Head, Mass., and in New Jersey green sand. It is
found among the prehistoric remains of the Swiss Lake dwellers. When
rubbed with a cloth it becomes excited with negative electricity. The
Greek word for it is electron, which gave the name electricity to the
modern science. Thales of Miletus, 600 B. C., and Theophrastus, about
300 B. C., both mention its electric properties or power of attracting
small objects when rubbed.