THE EXHIBITION OF 18G2. 
61 
if? caused to combine with the greatest possible amount of 
oxygen, becoming converted into sulphuric acid, or oil of vitriol 
as it is generally termed when in a concentrated form. Sul- 
phuric acid, which is also made from other sources of sulphur, 
is one of the most important chemical manufactures of the 
country, and upon it depends the equally important manufacture 
of soda from sea salt. An eminent philosopher* of our times 
has expressed the opinion that the commercial prosperity of a 
country may be estimated by the amount of sulphuric acid 
which it produces, and that the consumption of soda affords a 
fair criterion of a nation’s civilization, inasmuch as soap and 
glass, the manufacture of which depends upon these former, 
are inseparably connected with our ideas of cleanliness and 
comfort. Respecting the soap-test, there may be some reasons 
to question its accuracy, but the production of sulphuric acid 
lies at the root of nearly every industrial art or manufacture in 
which chemical agencies are employed, and may thus be looked 
upon as a fair test of the intellectual activity of a nation. 
We now pass on to the oily matter which is obtained in the 
distillation of coal. This is a very complex body, containing a 
large number of substances of different degrees of volatility, 
and varying greatly in their characteristics. Some are alkaline, 
as, for example, the now well known substance aniline, others 
are acid, but by far the greater portion are neutral. By ap- 
propriate chemical and mechanical means these components of 
the crude coal tar are each obtained in a state of purity. The 
lighter portions, known by the name of coal naphtha, consist in 
great measure of benzol, a liquid which has been for several 
years past applied to a considerable number of uses in the arts. 
For the present we will confine ourselves to the part which it 
plays in the production of the brilliant colouring matters, the 
manufacture of which is so well illustrated in the Eastern Annexe 
of the International Exhibition. When benzol is acted upon 
with strong- nitric acid it becomes converted into a heavy oily 
liquid, of a yellowish colour, which has an intensely sweet taste, 
and an odour powerfully recalling that of oil of bitter almonds. 
This is called nitro-benzol. It is employed to some extent in 
perfumery and in scenting soap, as well as in confectionary, 
where, owing to its non-poisonous properties, it forms a good 
substitute for the highly poisonous oil of bitter almonds. But 
the chief interest which attaches to this substance is on account 
of the transformation which it undergoes under the influence of 
cei'tain chemical reducing agents. To follow these different 
changes step by step would require us to devote some little 
space to chemical explanations and formulae, but a general idea 
* Baron Liebig : Familiar Letters on Chemistry. 
