6 BULLETIN 283, U. S. DEPARTMENT OF AGRICULTURE. 
allow the admission and exit of the gases, thereby causing them to 
mix intimately without seriously interfermg with the draft. 
Because of the doubtful stability of these inner walls and the 
serious damage caused on their collapse this method is no longer used. 
Gossage ! as well as several other investigators proposed fillmg the 
chambers with coke so that the gases would be obliged to work their 
way through the interstices and thereby become thoroughly mixed. 
This scheme, however, has been abandoned because of the impurities 
introduced into the acid by the coke and the tendency of the coke 
columns to press against the lead walls, causing them to bulge and 
even break. The lack of any cooling device in this process also 
caused excessively high temperatures in the chambers. 
Verstrart’s? plan is similar to the above, except that sine of 
bottomless stoneware jars filled with coke are used. The oxides of 
nitrogen are supplied to the system by allowing nitric acid to trickle 
down one of the stacks. 
In Pratt’s * process, which is much used in the Southern States, the 
gases are drawn through the first chamber by means of a fan, then 
through a tower packed with quartz down which flows dilute sul- 
phuric acid, and finally they are reinjected into the front of the first 
chamber by means of the same fan. This circulatory system seems 
quite efficient and a number of plants where the process is employed 
are operating on less than 9 cubic feet of chamber space per pound of 
sulphur burned in 24 hours. | 
Meyer’s‘* tangental chambers are designed both to mix and to ii 
the reacting gases at the same time. 
The chambers are cylindrical in form, the first having water- 
cooled lead pipes suspended around the circumference. The gases 
are admitted at a tangent near the upper part of the chamber walls 
and are discharged from outlets i the centers of the chambers’ 
bottoms. The gases are thus given a spiral motion which tends to 
mix them thoroughly while the water-cooled lead pipes reduce their 
_ temperature. 
There are three installations of this type of plant in the United 
States. One at least is reported to have given great satisfaction. 
Hartmann * obtained an increased yield of acid in the lead-cham- 
ber process by placing vertical, air-cooled lead pipes in the chambers. 
The chamber bottom is turned up around the lower ends of these 
pipes, forming hydraulic seals, and thus obviating the necessity of 
jomts in the bottom of the chamber. 
1 Lunge, Treatise on Manufacture of Sulphuric Acid, 1 Pt. I, p. 475. 
2 Bull. Soc. encour. ind. nat., 1865, p. 531. 
3 U.S. patents Nos. 546, 596, 652, 687. 
4 English patent No. 18376: Zeit. ftir ang. Chem. (1900), p. 742. 
5 Chem. Zeit., 1897, p. 877. 
