6 BULLETIN" 283, U. 3. DEPARTMENT OF AGRICULTURE. 



allow the admission and exit of the gases, thereby causing them to 

 mix intimately without seriously interfering 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 1 as well as several other investigators proposed filling 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 2 plan is similar to the above, except that stacks 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 3 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 4 tangental chambers are designed both to mix and to cool 

 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 in 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 5 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 

 joints in the bottom of the chamber. 



1 Lunge, Treatise on Manufacture of Sulphuric Acid, 1 Pt. T, p. 475. 



s Bull. Soc. encour. ind. rial ., 1865, p. 531. 



3 U. S. patents Nos. 546, 596, 652, 687. 



* English patent No. 18376: Zeit. fiirang. Chem. (1900), p. 742. 



t Chem. Zeit., 1897, p. 877. 



