Page:Manufacture Of Soda by Hou Te-Pang.pdf/30

Rh the reducibility of SO2 by solid carbon or carbon monoxide or water gas products according to the following reactions:

along with many side reactions. These reactions arc carried out in the presence of a catalyst. Various catalysts have been suggested, and even solid charcoal in the water gas generator may be considered as such a catalyst.

In summarizing, we might add that in England and on the continent, LeBlanc's process for soda manufacture has now disappeared, while in the United States, soda ash from the very beginning has been made exclusively by the ammonia process. At present, one part of the LeBlanc process is left in the form of hydrochloric acid manufacture:

and another, leaving out the limestone, is used in the manufacture sodium sulfide:

a slightly modified form, with the addition of pure quartz in place of limestone, is employed in the water-glass manufacture:

But the complete processfor the manufacture of soda ash has sunk into oblivion. In the matter of purity, cost of manufacture, labor involved in handling, and simplicity in the line of products obtained, LeBlanc's soda process cannot compete with the ammonia process. And for the production of caustic soda and bleaching powder, the present electrolytic method possesses every advantage: nobody nowadays would think of manufacturing bleaching powder from hydrochloric acid through the many intermediate stages represented by the Weldon or Deacon process. Indeed, the increased demand for chlorine has greatly spurred electrolytic production to such an extent that the quantity of caustic soda produced as a joint product from this electrolytic method has now equaled or exceeded that produced by the lime process, as will be seen in Chapters XIX and XX.