METALS, &C. 
65 
turned and welded, we have a still more elaborate pattern as the 
result. Gun barrels are now largely made of mild steel. 
The lower part of this Case is occupied by some fine examples 
of Bessemer steel from the Exhibition of 1862, presented by 
Sir Henry Bessemer. 
Illustrations of the Physical Properties of Metals. 
Case No. 14. 
A collection of specimens is here exhibited to illustrate the 
physical properties of metals, especially their malleability 
and ductility, and to show the advantage which is taken of 
such properties in applying metals to purposes of ornament. 
Malleability is the property of permanently extending without 
fracture when the substance is subjected to pressure, as in rolling, 
or to impact, as in hammering. The great malleability of copper 
is well shown by a penny-piece rolled out to a length of 
ten yards. Excellent illustrations are also furnished by Messrs. 
Tylor’s series showing the successive stages in the manufacture 
of a vase by hammering it into shape from a flat sheet. The 
large central ewer, of French manufacture, in the style of the 
Italian Renaissance, shows how copper admits of being beaten 
up ; and there are likewise examples of repousse work in silver. 
Specimens are also exhibited of copper sheathing, rolled zinc, 
sheet cadmium, u paper iron,” gold leaf, and various foils. 
Ductility, or the property of permanently extending, without 
rupture, when the substance is subjected to a pulling force, as in 
wire-drawing, is a property closely connected with malleability. 
Some examples of gilt silver wire, contributed by Messrs. F. and 
E. Stanton, are interesting as showing the great extension of 
which gold and silver are capable. 
There are also in this Case several coins and medals, showing 
the sharpness with which certain metals receive impressions 
when stamped. The old process of silver-plating is likewise 
illustrated. 
Large Mineral Specimens. Cases Nos. 21 and 31. 
Several fine mineral specimens, too large for exhibition in the 
wall-cases, are displayed in two Pedestal Cases, one on each side 
of the Museum. Case 21 contains, in the upper part several 
magnificent examples of Australian malachite, or green 
carbonate of copper ; whilst in the lower part attention may be 
called to a cleavage plate of selenite, of exceptional size and 
transparency, from a huge geode known as Selenite Mound, in 
Wayne Co., Utah, — a mound which was explored by Dr. Talmage, 
of Salt Lake City, who presented this and other specimens of 
selenite. 
In the opposite Case, No. 31, are some very fine examples of 
British lead-ores, chiefly from the great Exhibition of 1851. 
The eye of the visitor will also be arrested by some beautiful 
specimens of Japanese stibnite, or sulphide of antimony. 
