most valuable and important manure--in the form of ashes, by
substituting soda in the manufacture of glass and soap.

It is impossible to trace, within the compass of a letter, all the
ramifications of this tissue of changes and improvements resulting
from one chemical manufacture; but I must still claim your attention
to a few more of its most important and immediate results. I have
already told you, that in the manufacture of soda from culinary
salt, it is first converted into sulphate of soda. In this first
part of the process, the action of sulphuric acid produces muriatic
acid to the extent of one-and-a-half the amount of the sulphuric
acid employed. At first, the profit upon the soda was so great, that
no one took the trouble to collect the muriatic acid: indeed it had
no commercial value. A profitable application of it was, however,
soon discovered: it is a compound of chlorine, and this substance
may be obtained from it purer than from any other source. The
bleaching power of chlorine has long been known; but it was only
employed upon a large scale after it was obtained from this
residuary muriatic acid, and it was found that in combination with
lime it could be transported to distances without inconvenience.
Thenceforth it was used for bleaching cotton; and, but for this new
bleaching process, it would scarcely have been possible for the
cotton manufacture of Great Britain to have attained its present
enormous extent,--it could not have competed in price with France
and Germany. In the old process of bleaching, every piece must be
exposed to the air and light during several weeks in the summer, and
kept continually moist by manual labour. For this purpose, meadow
land, eligibly situated, was essential. Now a single establishment
near Glasgow bleaches 1400 pieces of cotton daily, throughout the
year. What an enormous capital would be required to purchase land