12 



BULLETIN 283, U. S. DEPARTMENT OF AGRICULTURE. 



that the lead, lead oxide, or lead sulphate had something to do with 

 the very efficient yield of acid obtained when using the lead spiral. 

 Accordingly, a'glass coil of the same length and internal diameter was 

 substituted in the experiments shown in Table III. 



Table III. — Sulphur dioxide oxidized to sulphuric acid in apparatus shown in figure 1 . 

 Glass spiral used and steady stream of oxides of nitrogen furnished. 



Number of run. 



Time of 

 run. 



Rate per 



hour of 



S0 2 . 



SO2 oxidized in 

 system. 



SOslost 

 in 



system. 



S0 2 

 escaping 



In vessel 

 A. 



In glass 

 spiral B. 



from end 

 of spiral. 



20 



Hours. 



n 

 n 



2" 



Grams. 

 3. 8311 

 4. 6404 

 5. 7888 



Per cent. 

 14.17 



43.C9 

 20.1S 



Per cent. 

 75.14 

 50. IS 

 71.63 



3.15 

 3.20 

 1.26 



Per cent. 

 7.34 

 2.63 

 6.28 



19 



12 





Table III shows that the yield of acid was not so great with a glass 

 as it was with a lead spiral. In no instance was the gas run through 

 the apparatus so fast as in the experiments in Table II, yet even 

 though the oxides of nitrogen were present in large quantities in the 

 gaseous mixture there was a loss bf sulphur dioxide from the end of 

 the spiral. 



In order to try out the catalytic action of the lead coil, several runs 

 were made with both the glass and lead spirals, but using no oxides of 

 nitrogen. The results of these experiments are shown in Tables IV 

 and V. 



Table IV. — Sulphur dioxide oxidized to sulphuric acid in apparatus shown in figure 1. 

 Lead spiral used, but no oxides of nitrogen employed. 



Number of run. 



Time of 

 run. 



Rate per 



hour of 



S0 2 . 



SO2 oxidized in 

 system. 



S0 2 lost 



in 

 system.! 



SO = 

 escaping 



In vessel 

 A. 



In spiral 

 B. 



from end 

 of spiral. 



21 



Hours. 

 1 

 1 



Grams. 

 3.2642 

 3. 8459 



Per cent. 



0.40 



.41 



Per cent. 

 38.08 



40.78 



Per cent. 



Percent. 

 61.52 



16 





58.81 









1 Could nottoe determined. Included in figures in column 5. 



Table V. — Sulphur dioxide oxidized to sulphuric acid in apparatus shown in figure 1 

 Glass spiral used, but no oxides of nitrogen employed. 



Number of run. 



Time of 

 run. 



Rate per 



hour of 



SO2. 



. S0» oxidized in 

 system. 



S0 2 lost 



in 

 system. 



SO2 

 escaping 



In vessel 

 A. 



In spiral 

 B. 



from end 

 of spiral. 



18 



Hours. 

 10 

 10 



Grams. 

 2. 6713 

 2.8393 



Percent. 



0) 



0.40 



Per cent. 



0.75 

 0.68 



Per cent. 

 2 10.02 



Per cent. 



15 



86.56 







1 Included in next column. 



2 The large loss of sulphur dioxide in the system was due in part to the renewal of the sulphuric acid in 

 the wash bottle through which the gas was allowed to bubble before entering the system. This acid was 

 not entirely saturated with SO2 before these experiments were undertaken. 



