THE SCIENCE OF THE EXHIBITION.

double sulphuret of copper and iron, are abundantly displayed; a considerable
improvement has been effected; since the
and the large copper smelters of Swansea exhibit illustrative restrictive
duties have been removed, manufacturers being
specimens of every stage of a process, regulated at each step  enabled, without
the annoying interference of the Excise, to
by a knowledge of physics and chemistry, which is necessary  try an experiment,
it will be seen that the quality of our crystal
for the production of copper, in such a state of purity as to be -flint glass
with lead-has been improved, and that the
fit for the use of the manufacturer, or for the purposes of that colours
imparted by the metallic oxides are far more brilliant,
most permanent form of Art-bronze statuary. Zinc ores in transparent, and
intense than before.
the same way tell their own instructive story. If we take the  The subject
of silvering glass is a curious one -and the ex-
trouble to examine the stages of reduction and manufacture amples of the
most recent improvements of precipitating silver
and thus trace the metal from the ore to the finished work, with grape sugar,
found in the contributions to the Exhibition,
the value of mineralogy, qf chemistry, and of natural philosophy  are excellent.
We are not, however, sure that the silvering of
will be seen. The same may be said, even more strongly, of coloured glass,
and thus depriving it of transparency, is
iron. The iron ores of the United Kingdom, collected with  altogether what
we desire, although we freely admit that many
infinite labour by Mr. Blackwell, show the variety we possess, new and not
unpleasing effects can be produced by the process.
and in the large contributions of iron ores from Canada, Nova We are very
anxious to see the process extended to silvering
Scotia, and the IUnited States, from Prussian Germany, Sweden, plates of
glass, as, by the application of such a method, the
and Russia, we have such means of comparison as never before sad effects
which are known to arise from the absorption of
could be obtained. Our own iron-masters have fully illus- quicksilver by
the skin would be got rid of. Humanity calls
trated the processes of iron smelting; and our manufacturers for an extension
of the application in this direction, and we
have exhibited every form of iron-work from the saucepan to  trust the very
enterprising patentees will prosecute their
the sword-blade; from  the candlestick to the ornamental experiments with
this view.
casting. Swedish and Russian iron, in all stages, are shown;  In immediate
connection with the process, because illus-
and the Berlin castings, so long famous, are abundantly trated by it, we
may refer to the brilliancy of colour produced
displayed. Mineralogy will here have its work of classification; in our English
flint glass. Since the glass-maker has suc-
chemistry its important business of analysis; and physics ceeded in rivalling
the Bohemian in his tints, the reflection
is called into full play in the arrangements of the blast and  through these
from the silvered surface, teaches us that colours
puddling furnaces, in the economy of fuel, in the application  are produced
which are curious in their effects, and physically
of the gaseous products, and in the new process of using gas interesting.
It has been proved that almost every variety of
in the operation of puddling. Upon the character of the ore, colour can be
produced in glass by very dissimilar agents; that,
and the perfection of the processes of reduction, depends the indeed, charcoal,
iron, gold, &c., may be made to impart to glass
condition of the finished work.                             nearly all the
colours of the chromatic scale, by modifying the
  At present, it is impossible to do more than indicate the amount of heat
to which the composition is exposed. It will
illustrations of science which are spread around; but we however, be found
that, if the colour transmitted is the
can return to the subjects, and explain fully all that is same, the colour
reflected is different. There is, in nearly
novel and instructive in each particular class, as it falls every variety
of coloured glass, to be detected a certain
legitimately under consideration in a close survey.    In  dichroism. We
often find a glass, yellow by transmitted light,
that chemical department which connects itself with the which exhibits a
blue colour at certain angles of reflection,
Mineral kingdom, we find illustrations of white lead manu- and the same is
often, although less frequently, seen with the
facture, and also the processes of obtaining white zinc-of ruby glasses.
By the silvering process, this reflected colour
the preparation of Prussian blue-soluble and insoluble, and, is considerably
exalted, and this dichroism is very pleasingly
indeed, all those pigments which result from the combina- illustrated.
tions of oxygen, sulphur, arsenic, or other substances, with  The southern
wall of the building is covered with such a
the metallic bases. We have the separation of wolfram from  display of Decorative
Art as we have never witnessed, and
tin ore, which is sadly injurious to it-and the conversion of there is scarcely
a specimen of Art or Manufacture there which
the tungsten into an oxide, and into tungstate of soda, is not an illustration
of the present subject. Numerous speci-
forming a new mordant for the calico-printer, and also the mens of gypsum,
both amorphous and crystalline,-as nature
production of a new colour from the same substance: we gives it to us, will
be found in the various departments; the
beieve by passing coal gas over the oxide, by which the resulting plaster
of Paris-so called from the circumstance
metallic tungsten is reduced in a peculiar condition, probably that it is
found in great abundance in the neighbourhood of
mixed with carbon. Then we find all the products from       the French capital,
being largely worked at Montmartre-
peat-which, if the question of economical production can   forms also an
article of exhibition; but to the various means
be satisfactorily answered, promises to convert the bogs of which have been
adopted to give hardness and durability to
Ireland and Dartmoor, into sources of much wealth ;-and    this material,
so exceedingly valuable for procuring casts,
many other illustrations of the available application of sub- we would particularly
direct attention. Plaster of Paris casts,
stances which have not been hitherto employed,              it is well known,
are porous and absorbent, and hence the
  Many remarkable examples will be found in the China clays necessity of
painting them to preserve their surface, and even
(Kaolins) of the St. Austle district, and from Dartmoor; the this has proved
exceedingly inefficient. Among the beautiful
clays from other localities are also shown in considerable specimens of Art
adorning the southern walls of the
variety, and we shall find specimens of each form  of the English division-which
extend from     the sculpture court
ceramic art, resulting from the use and mixture of these immediately adjoining
the transept to the western end-will
materials,                                                  be discovered
'several examples of processes by which ,the
  As we expected, the potteries have made a display in every  plaster of
Paris is hardened to such an extent that a high
respect creditable to England. Not only have we our old polish can be given
to its surface. In some cases where these
familiar earthenware somewhat refined, but we have "lhara  cements have
been employed, it has been found that the
porcelain" in a state of great perfection, and some beautiful effect
of them  has been materially lowered by a constant
examples of egg-shell, china.  I decoration, too, the stimulus efflorescence
over the surface. This would appear to arise
which has been applied has evidently produced a considerable from the presence
of soda, which it is well known is liable
advance in the right direction. We have colours which are to effiorescence,
and it is prevented by giving an acid rather
new or revived, and a considerable improvement in many     than an alkaline
reactio'n to the composition. The silicate
which have been long employed. Among the revivals, we of potash, formed by
dissolving flint in caustic potash under
cannot but notice the beautiful Rose Dubarry, which is pressure, has the
property of cementing sand into a very
certainly an exceedingly beautiful example of the old Se'vres solid stone:
this preparation has also been employedfr


              colour. ~ ~      ~                         _fir.~.        
                                  ...
         In glass, whether we linger over the sheet glass covering fresco-paintings;
giving to them, by the application
prepared by Messrs. Chance for the Industrial Palace itself, of this soluble
glass, a very perfect impervious glaing by
or the enormous shades, the largest ever made by man, which they are protected
from the influence of the atmosphere.
or paus on to the plate and flint glass, it will be found that Messrs. Ransom,
of Ipswich, exhibit some specimens of their