PEODUCTIOlsr 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 sulpnurio 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 hi 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 Boeing * 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 



i German patent No. 71908. 



