PRODUCTION OF SULPHURIC ACID. 



13 



In comparing the results obtained in Tables IV and V it is evident 

 that the lead spiral had some influence in the oxidization of the sul- 

 phur dioxide to sulphuric acid. The figures in column 5, Table IV, 

 are obviously too high since all the ^errors due to the loss of gas in 

 the system are thrown into this column. But while the sulphur 

 dioxide and air was in each instance run through the lead spiral at 

 greater speed than through the glass coil, the quantity escaping 

 oxidation was much less in the former than in the latter case. 



In order to determine if the catalytic action observed in the lead 

 coil was due to lead or lead sulphate, two experiments were con- 

 ducted using the glass spiral but no oxides of nitrogen. The con- 

 ditions in these experiments were approximately the same as in 

 those recorded in Table V except that in the first run the interior 

 of the glass coil was coated with precipitated lead sulphate and in 

 the second a lead chain was introduced into the glass spiral. The 

 results are shown in Table VI. 



Table VI. — Sulphur dioxide oxidized to sulphuric acid in glass spiral coated with lead 

 sulphate and in the same spiral after the introduction of a lead chain. 



Number of run. 



Time of 

 run. 



Coil 

 used. 



Rate per 



hour of 



S0 2 . 



SO2 oxidized in 

 system. 



S0 2 lost 



in 

 system. 



S0 2 

 escaping 



In vessel 

 A. 



In spiral 

 B. 



from end 

 of spiral. 



22 



Hours. 

 1.0 

 1.0 

 1.5 



?1 



C 1 ) 



Grams. 

 2. 6594 

 1. 7523 

 2. 5299 



Per cent. 

 0.25 

 0.09 

 0.05 



Per cent. 

 9.80 

 53.60 

 17. So 



Per cent- 

 ( 2 ) 

 ( 2 ) 

 ( 2 ) 



Per cent. 

 89.95 



23 



46 31 



24 



82.10 







1 Class coil coated with lead sulphate. 



2 Not determined. 



3 Glass coil containing lead chain. 



Here again, as in Tables II and IV, the amount of sulphur dioxide 

 lost in the system could not be determined, but the results shown in 

 Table VI indicate that while lead sulphate has some influence on the 

 oxidation of sulphur dioxide, lead or lead oxide is a much more 

 energetic catalytic agent. The presence of the oxides of nitrogen in 

 the system, however, is necessary for the complete oxidation of sul- 

 phur dioxide to sulphuric acid. 



FACTORY CONSIDERATIONS. 



In the construction of a sulphuric acid plant along the lines of the 

 apparatus described in this paper, it is proposed to dispense with the 

 lead chambers and intermediate towers only. The lead spiral is not 

 intended to replace the Glover tower, which is so important in the 

 preliminary mixing and cooling of the furnace gases and in restoring 

 the oxides of nitrogen to the system, nor is it intended to do away 

 with the Gay-Lussac tower, which is essential for the recovery of 

 these same oxides of nitrogen from the residual gases. 



