SMOKE AND DUST ABATEMENT COTTRELL. 671 



FIRST COMMERCIAL INSTALLATIONS. 



These experiments at Pinole attracted the attention of the Selby 

 Smelting & Lead Co., whose smelter, located at Vallejo Junction, a 

 few miles farther up the bay, was at that time the object of injunc- 

 tion proceedings brought by the farmers of the surrounding coun- 

 try. At the time the suits originated three separate stacks at the 

 smelter contributed to the alleged nuisance. The first, and admit- 

 tedly the most serious offender, handled the gases from the lead blast 

 furnaces and discharged several tons of lead fume daily into the 

 air. Shortly before the commencement of electrical precipitation 

 work at the plant this had been obviated by the installation of the 

 bag house,^ shown in figure 8. After correcting this evil there still 

 remained, however, a stack discharging the gases from the roasters, 

 which, besides the invisible sulphur dioxide, furnished dense white 

 clouds, consisting chiefly of sulphuric acid, arsenic, and lead salts, 

 and to which the bag house was inapplicable on account of the corro- 

 sive action of these gases upon the bags. Lastly there was the stack 

 of the refinery carrjdng the mists escaping from the pots of boiling 

 sulphuric acid used to dissolve the silver out of the gold and silver 

 alloy coming from the cupels. 



The blast furnace and the roaster stacks each carried something 

 over 50,000 cubic feet of gas per minute while the refinery stack 

 represented scarcely a tenth of this volume. xVs a first step operations 

 were accordingly commenced on this latter, and after several months' 

 experimenting as to the best form of construction a system of ver- 

 tical lead plates 4 inches wide by 4 feet in length and spaced about 4 

 inches apart was adopted. Several rows of such plates were as- 

 sembled in a 4 by 4 foot lead flue. Between each pair of plates hung 

 a lead-covered iron rod carrying the asbestos or mica discharge ma- 

 terial, the latter finally proving the more serviceable in this highly 

 acid atmosphere. These rods or discharge electrodes were supported 

 on a grid work of buss bars extending over the heads of the plates 

 and through apertures in the sides of the flue to insulators on the 

 outside. Figure 9 is a view looking down on the top of this flue with 

 the cover removed from above the electrodes, and figure 10 is a vieAv 

 inside the flue looking through the system of electrodes. Figures 11 

 and 12 shoAv the effect on the appearance of the stack when the elec- 

 tric circuit is respectively open and closed, the stack in the immediate 

 left foreground being the one into which this flue discharges. The 

 large stack in the middle background is from the roasters to be dis- 

 cussed below. Figure 13 shows the corresponding stream of dilute 

 sulphuric acid (about 40° B.; running out from the flue as pre- 



iFor detailed description see Eng. Min. Journ. vol. 86, pp. 451-457 (1908). 



