166 Prof. Royle’s Lecture on the Great Exhibition of 1851. 
we have had a variety of articles at the Exhibition. Most of 
these have been greatly admired for the elegance of their form, 
as well as for the gracefulness of the patterns with which their 
surface is engraved. Though the groundwork of this composition 
appears of a blackish color, its natural color is that of pewter or 
of zinc. Dr. Heyne informs us that it is composed of copper 
sixteen ounces, lead four ounces, tin two ounces. ‘These are 
melted together, and to every three ounces of the alloy sixteen 
ounces of spelter, that is of zine, is added, when the alloy is 
melted for use. But to give the whole the black color which is 
esteemed, probably from bringing out the pattern, it is dipped 
into a solution of sal-ammoniac, saltpetre, common salt, and blue 
vitriol. 
Dr. B. Hamilton saw of zinc 12,360 grains, copper 460 grains, 
and lead 414 grains, melted together, and a mixture of resin and 
bees-wax introduced into the crucible to prevent calcination. It 
was then poured into a mould made of baked clay, and the arti- 
cle handed over to be turned ina lathe. Artists then inlay flow- 
ers or other ornaments of silver or of gold. They first rub it 
over with sulphate of copper and water, which gives the surface 
a blackish color, and enables the artist more easily to distinguish 
the figure which he draws,—this he does with a sharp-pointed 
instrument of steel, and cuts it with small chisels of various 
shapes, and then with a hammer and punch fills the cavities with 
small plates of silver, which adhere firmly to the Bidery. It is 
then polished and stained as described above. The various arti- 
cles made from it are vases, wash-hand basins and ewers, hookah- 
bottoms, spittoons, cups and dishes, small boxes and weights. 
‘These are inlaid commonly with silver, but sometimes with gold. 
‘The patterns are usually as much to be admired as the forms of 
the vessels. Though usually called Bidery, sometimes Vidry, it 
is also manufactured at others places. Specimens have been sent 
both from Bider and Aurungabad, in the Nizam’s territories, from 
his Highness the Nizam and his minister, Siraj-ool-Moolk, which 
are peculiarly beautiful. Some also from north-west India, am 
from Bengal; the latter, however, was inferior to the others 10 
workmanship. Bidery does not rust, yields little to the hammer, 
and breaks only when violently beaten. According to Dr. Ham- 
ilton it is not near so fusible as zine or tin, but melts more easily 
than copper. 
ss.—Glass is one of those discoveries which could hardly 
glass was made previous to colorless glass. 
