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REPORT OF THE FISH AND GAME COMMISSION. 



Particular attention lias been paid to pollution by oil and lampblack. 

 The problem confronts the gas companies of devising a rapid and con- 

 tinuous filtering system which will retain all of the lampblack and thus 

 allow the water to return to the bay or stream perfectly clean. The 

 magnitude of this undertaking will be better realized when it is under- 

 stood that an average of twenty-two pounds of lampblack is produced to 

 each thousand cubic feet of gas, and that San Francisco alone, during 

 the month of January, 1916, manufactured 613,947,000 cubic feet of 

 gas, and about 4000 tons of lampblack. 



Fig. 76. Detail view of baffles of the Standard Oil Company plant at Richmond. The oil 

 collects behind the baffles and is skimmed and pumped back into the separator. 

 Photograph by A. M. Fairfield. 



To meet this situation the Pacific Gas and Electric Company has, in 

 the bay counties alone, spent not less than $100,000 during the last two 

 years. The old system of settling pits, which required a large area to 

 operate successfully, has been finally and definitely abandoned, and 

 attention turned to newer devices. All known filters have been tried 

 with more or less success. Straw filters were found to work very satis- 

 factorily where the lampblack production does not exceed 5000 pounds 

 per day, and a model filter of this type was installed in the Vallejo 

 plant. In the larger plants this filter is too slow and expensive. A 

 straw filter similar to the one at Vallejo, but of less capacity, is under 

 construction at Napa. 



The three best known types of mechanical filters for handling lamp- 

 black are the Oliver, the Kellev, and the Butters. All of these originally 



