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. 
SO> oxidized in 
system. SO 
. : Rate per 2 
Time of Coil SO2 lost | escaping 
SUEECIOSe OTE run, used. nour ©: in | fromend 
2- | In vessel | In spiral | system. | of spiral. 
SN AR B. 
Hours. Grams. | Per cent. | Per cent. | Per cent. | Per cent. 
VPA SES 0 Se ae ee a eee 1.0 (1) 2. 6594 0. 25 9. 80 (2) 89. 95 
aia late i ta Oar ate dene, Gieene fe teem 1.0 (3) 1.7523 0. 09 53. 60 (2) 46.31 
DA ce es eps ee epee A x0 5 (4) 2. 5299 0.05 17. 85 (2) 82.10 
1 Glass 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. 
