672 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1913. 



cipitated. When the acid kettles are at a full boil it often amounts 

 to over 2 gallons a minute. 



The electric current is taken from the power circuit of the plant at 

 400 volts, GO cycles, and transformed up to 17,000 volts thence 

 through the synchronous contact maker or rectifier to the electrode 

 system. At first a glass-plate condenser was connected across the 

 high potential line in parallel with the electrode system in order to 

 assist in maintaining the potential of the electrodes between the in- 

 tervals of contact, but was found troublesome and unnecessary in 

 practice and in this and other installations is now omitted. 



The power consumption for this installation is about 2 kilowatts, 

 including the driving current for the synchronous motor, and the 

 Avhole apparatus requires no more attention than a feed pump or a 

 blower. This appears to have been the first commercially successful 

 installation of electrical precipitation ever made, and has now been 

 in regular daily operation for over seven years at a cost for labor 

 attendance and repairs of less than $20 a month. In fact, while the 

 plant Avas making enough bluestone to utilize all the weak acid re- 

 covered, the saving on purchase of the latter paid for the entire cost 

 of operating five times over. 



. In the seven years which have elapsed since this installation was 

 made the processes have undergone steady development, and inci- 

 dentall}?^ have passed through the many vicissitudes common to in- 

 novations in the industrial world. One of the first extensions of the 

 work was naturally a series of experimental precipitation chambers 

 in the main roaster flue of the same w^orks. Two different forms of 

 these are seen in figures 14 and 15. The former was of lead con- 

 struction similar to that of the first installation but of some ten- 

 fold larger capacity, while the latter Avas of brick and iron construc- 

 tion and intended for the collection of drier and less highly acid- 

 bearing material. Figures 16 and 17 show the 9-foot diameter brick 

 stack discharging these gases with the electric current respectively 

 off and on. Later, fundamental changes in the furnace equipment 

 and metallurgical practice at this plant, obviated the need for elec- 

 trical precipitation and the permanent installation originally con- 

 templated for these particular flues has never been carried out. 



OPERATIONS IN SHASTA COUNTY. 



The installation next in order of size to be undertaken was at the 

 Balaklala Smelter at Coram, Shasta County, Cal., 273 miles north 

 of San Francisco on the main line of the Southern Pacific Railroad 

 to Portland and Seattle. The vast body of low-gi-ade copper ore 

 reaching for many miles across tliis county and commonly Iniown as 

 the Copper Crescent, has been described in detail by L. C. Grafton ^ 



1 IT. S. Geological Survey, Bull., 4?.0b. 



