BRASS. PINCHBECK. 187 
ceptible of alloy. The most frequent and useful of 
these alloys are made with copper and zinc, in different 
proportions. 
Brass is an alloy composed of three parts of copper, 
and about a fourth part of zinc (241). It is a beautiful, 
useful, and well-known yellow metal. Not being so apt 
to tarnish and rust as copper, and being, in other re- 
spects, better adapted for the purpose than that metal, 
it is much used for clock-work, and for mathematical 
and astronomical instruments. It is more ductile than 
either copper or iron, and hence is peculiarly fitted to 
be made into wire, for the strings, of musical instru- 
ments, and other purposes. Sieves are woven with brass 
wire, after the manner of cambric weaving, and of such 
extreme fineness that similar ones could not possibly be 
made with copper wire. Brass wire, flatted and gilded, 
is sometimes made into lace. The finest brass is manu- 
factured at -Geneva. It unites great beauty of colour 
to a high degree of ductility ; and is used chiefly for 
escapement wheels, and other nicer parts of watch- 
making. For work in which there is no friction it is 
necessary to cover brass with a kind of varnish or laquer, 
to improve its colour, and prevent it from being tar- 
nished by exposure to the atmosphere. 
Prince's Metal, or Pinchbeck, is an alloy containing 
three parts of zinc (241), and four of copper. This 
metal has nearly the same colour as gold, and was for- 
merly much in use for the manufacture of ornamental 
articles of different kinds. 
Dutch Gold is formed by the cementation of copper- 
plates with calamine (21<1), hammered out into leaves. 
This article is chiefly manufactured in Holland and Ger- 
many, and has about five times the thickness of gold leaf. 
Bronze, and the metal of which cannons are made,, con- 
sist of from six to twelve parts of tin (238) combined 
with 100 parts of copper. This alloy is brittle, heavier 
than copper, and of a yellow colour. Before the me- 
