PRODUCTION OF SULPHURIC ACID. 5 
the system, sulphuric acid being formed till the sulphur dioxide is 
practically exhausted. 
The residual gases, consisting of nitrogen, oxides of nitrogen, some 
oxygen, and a small percentage of sulphur dioxide, then enter the 
lower part of the Gay-Lussac or recovery tower, which is similar in 
construction to the Glover tower, except that it is usually taller and 
wider (from 40 to 50 feet high and 8 to 15 feet across) and filled with 
coke instead of quartz. Strong sulphuric acid (1.5 to 1.7 specific 
gravity) trickles down the tower, absorbing the oxides of nitrogen 
from the residual gases which ascend through the coke column, and 
are finally discharged through a stack. The nitrous vitriol formed is 
then pumped to the Glover tower, diluted with water, and distributed 
as previously described. 
MEASUREMENT OF A PLANT’S EFFICIENCY. 
The efficiency of a lead-chamber plant is measured, first, by the 
amount of chamber space required for each pound of sulphur burned 
in 24 hours and the amount of acid (50° or 60° B.) made therefrom, 
and, second, by the amount of niter consumed or lost in the production 
of this acid, 
Practically all sulpnuric acid authorities agree that, provided the 
gases are present in the proper proportions, the two most important 
conditions necessary for efficient production are a thorough mixing 
of the gases and the control of their temperature. 
The importance of the first of these conditions is self-evident, 
since in order to bring about complete chemical reaction the reacting 
substances must be in intimate contact with one another. The 
second condition is important because too low a temperature lessens 
the chemical activity of the gases, while a temperature above 100° C. 
prevents the condensation of water which it is claimed is necessary 
to bring about the decomposition of nitrosulphuric acid, an interme- 
diate compound formed from the oxides of nitrogen in the system. 
Numerous schemes to control these conditions have been devised, 
some of which have features of considerable interest and practical 
importance. While it is impracticable in a paper of this length to 
discuss in detail all of these processes, several that have been tried, 
apparently with some success, are described below. 
METHODS FOR ACCELERATING THE CHAMBER REACTIONS. 
Walter and Boemg! advocate the use of several hollow acid-proof 
partitions built across the chambers and so arranged that the gases 
enter the compartments through large holes near the bottom and are 
discharged from holes near the top.: Numerous other small holes 
1 German patent No. 71908. 
