Page:Popular Science Monthly Volume 61.djvu/33

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SULFURIC ACID.

the contact substance, that of reducing the platinum by the use of formic acid salts. This keen discovery of Winckler's brought at once into existence a new industry, that of the synthetic manufacture of fuming sulfuric acid. A number of works immediately adopted Winckler's process, among them first the Badische Anilin-und Soda-Fabrik, while the monopoly of Stark in Bohemia was broken. The whole industry therefore owes Winckler a debt of gratitude for this advance in technology.

Further work in this field was wholly under Winckler's influence. This is true of the patent secured ten years later by Haenisch and Schroeder, who replaced pure oxygen by atmospheric air, retaining, however, the use of pure sulfur dioxid, and compensating for the diluting influence of the nitrogen by carrying on the reaction under pressure, in order, as the patent reads, that the molecules of the gases may be brought closer together. This process also was put into practical application in the Badische Anilin-und Soda-Fabrik.

Messel and Lunge proposed a method of obtaining a stoichiometric mixture and at the same time excluding the atmospheric nitrogen by burning the pyrites with pure oxygen. All these processes were unsuited by their very nature to compete with the lead chamber process and were necessarily confined to the manufacture of the fuming acid. Nevertheless attempts at the solution of the larger problem were by no means wanting; little, however, regarding them made its way to the notice of the public. Winckler especially published nothing regarding his new work along this line, so that it only became known last year, through the striking lecture of Lunge and Winckler in Hannover on the development of sulfuric acid manufacture, that at his instance it had been found possible at the Mulden works to convert from two thirds to three fourths of the sulfur dioxid in the pyrites-burner-gases into sulfuric acid.

 

Purification of the Gases.

The solution of the problem of the complete conversion of the burner-gases into sulfuric acid remained unsolved, and indeed at that time, as far as was known, theoretically or practically, was unsolvable. Nevertheless, as I attacked the problem at the Badische works, it was chiefly theoretical considerations which made the possibility of attaining this great goal seem not absolutely out of the question.

It is well known that in the lead chamber process there is always an excess of six volumes per cent. of oxygen in the gases as they leave the chambers. In working with pyrites-burner gases under similar conditions, there would naturally always be this excess of oxygen, whatever contact-method was employed for making the acid, and it could not be understood why in spite of such an excess of oxygen the reaction should not proceed quantitatively. The question was tested