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6 in making concentrated sulfuric acid, picric acid, poisonous gases, and other war chemicals for the British Government.

After the war, the chemical industries bad to readjust themselves. Competition among the different nations for the world market was resumed with even greater vigor. Efficiency was the watchword; and the LeBlanc process, which involved much labor, high cost of manufacture, low purity, and a complex line of products, had to give way to a newer, more efficient process. In 1923, The United Alkali Co. decided to scrap the last portion of its LeBlanc soda equipment, and the death verdict for the LeBlanc process for soda ash manufacture was finally delivered. On the European continent similar conditions occurred, although the remnants of the LeBlanc process in many places did not even survive up to the War. Born of necessity during the War in France and superseded because of the necessity caused by the World War I, the LeBlanc process, which had served mankind for fully a century, had completely fulfilled its mission. We shall now dwell at some length upon the relationship between the LeBlanc soda industry and the other chemical industries.

Though the LeBlanc process was discontinued, LeBlanc soda works remained. The United Alkali Co. in England became engaged in the manufacture of various heavy and fine chemicals. The change consisted merely in replacing the LeBlanc process for soda manufacture by the ammonia process at Fleetwood. And now this United Alkali Co. became indeed the largest manufacturers of sulfuric acid in England, as if the name of the company were a misnomer. The reason is to be found in the nature of the LeBlanc process. It requires for one of its principal raw materials salt cake, or sodium sulfate, which in turn has to be made from common salt by treatment with sulfuric acid. Thus, sulfuric acid indirectly becomes its important raw material. The LeBlanc soda manufacturers generally made their own sulfuric acid. Thus we find that they were also large manufacturers of sulfuric acid (chamber acid). From salt and sulfuric acid are obtained salt cake and hydrochloric acid, which latter is in itself a valuable chemical. Hence we find that LeBlanc soda manufacturers are necessarily manufacturers of hydrochloric acid. As the muriatic acid as such did not find much use at the earlier time, most of it was converted to chlorine; from this, bleaching powder was made which found very extensive application in the textile and paper industries. Thus, the bleaching powder industry was necessarily connected with the LeBlanc soda industry. The salt cake required by glass manufacturers was also supplied by LeBlanc soda manufacturers. The CaS residue known as "tank waste" proved be quite a nuisance, for there was so much of it that its disposal became a problem. For every ton of soda ash produced there were more than $1 1⁄2$ tons of this waste left. So foul was its odor and so objectionable was the pollution of surface water by it that its proper disposal became a matter of no small concern to the community. Added to this was the fact that it contained all the sulfur originally present in the sulfuric acid. The recovery of sulfur was finally worked out and exceptionally pure sulfur was obtained as another by-product.