Page:Manufacture Of Soda by Hou Te-Pang.pdf/18

 Chapter 1 Introduction. Historical Survey of Alkali Industry and Relation of LeBlanc Soda Industry to Development of Other Chemical Industries We shall first discuss the LeBlanc process and its historical relation to the development of other chemical industries. In the early part of their work students of elementary inorganic chemistry come across such processes as the Weldon process, the Deacon process, and so forth; but prob- ably they do not realize the close bearing of these processes on the LeBlanc soda industry. In the discussion which follows, the development of the LeBlanc soda industry will constitute a historical treatment of the early chemical industries with the LeBlanc process as their nucleus. With the passing of the LeBlanc process as an active method for the manufacture of soda, most of those industries must necessarily also pass into oblivion, but the foundation laid by the LeBlanc soda industry in paving the way for the more modern chemical industries is well worth consideration.

The artificial soda industry originated in France, but for its development and application we must turn to England. France, as a leading nation in Europe in the Eighteenth Century, consumed considerable quantities of soda annually. While she was engaged with England in the so-called "Seven Years' War" and with practically all Europe in the Napoleonic wars, the source of Spanish barilla was closed to her. She had find some way to get soda. In 1775 her Academy of Science offered an award of 2400 livres for the invention of a practical process for the manufacture of soda. It was known in a vague way before this time, that soda could be made from common salt, for, in 1773, Schecle was able to get some caustic soda by digesting litharge in strong brine according to the following reaction:

where x=2, 3, 4 or 5 according to the concentration of the brine. The filtrate of brine from the mixture of PbO and PbCl2, contains some caustic soda, and the conversion decreases as the tenperature employed is raised, owing to the greater solubility of PbCl2, at a higher temperature.

Among several methods presented, there was one by Nicolas LeBlanc (1742-1806), who outlined a method of manufacture starting with common salt. His process was so promising that in 1783 the French Academy