SALT FROM SEA WATER 21 



latter part of November. The crystallized salt is broken with a special plow and 

 then gathered by a dragline into small two-way dump cars on 36-inch tracks. A 

 small gasoline "locomotive" hauls the loaded cars out of the crystallizing pond and 

 the salt is dumped into a V-shaped bin about 100 feet long, 4 feet wide, and 4 feet 

 deep. Its sides are sloping and the bottom is provided with rack and pinion gates 

 which are operated from above by hand wheels. In this manner the salt is dis- 

 charged to a screw conveyor which works it to a belt elevator. This elevator dumps 

 the salt into the "washer", a trough 2 feet wide, 4 feet deep, and 30 feet long with a 

 screw conveyor in the bottom. The salt is washed by working it through the 

 trough against a current of brine from the "pickling" pond (density about 

 12.5° Be., 1.0944 sp. gr.). The brine flows back to the pond after passing through 

 the trough. 



The screw conveyor from the washer delivers the salt to a bucket elevator which 

 lifts it about 50 feet. The salt receives a final brine washing at the bottom of the 

 bucket elevator and passes under a spray of fresh water as it is elevated. This 

 removes any dirt or mother liquor that may have escaped previous washings. 

 According to Palmer, "the dried product analyses 99.823 per cent NaCl. The small 

 amount of impurities which does remain consists of sulfates of calcium, mag- 

 nesium, and sodium, and chlorides of calcium and magnesium." The bucket ele- 

 vator dumps the salt into another trough, containing a screw conveyor which 

 works it out on a trestle. Gates in the bottom of the trough permit its discharge 

 at any desired point to large stock piles which are usually 50 feet high. 



After the salt has dried to 1.5 to 2.0 per cent moisture, it is shipped in sacks or 

 bulk as needed. Belt conveyors carry the salt from the stockpile to a permanent 

 screening and loading plant. The salt is elevated by bucket elevator and screened 

 into 3 sizes. It is then carried to 4 large bins of 100 tons capacity each and either 

 sacked in various size bags from these bins or run on a belt directly into freight 

 cars for shipment in bulk. 



The annual output of the plant of the Western Salt Company, which has been 

 described, is from 50,000 to 60,000 tons. 



The salt-making operations of the plants around San Francisco Bay are con- 

 ducted in a similar manner although differing in some details. As in the San Diego 

 district the bay water is not taken into the works continuously, but only when the 

 tides are highest. Evaporation proceeds more slowly, and, consequently, the annual 

 yield per acre is somewhat less. The rainfall and evaporation in inches during the 

 salt-making season at San Francisco Bay are given below: 



The salt content of San Francisco Bay is lower than that of San Diego Bay, 

 Comparative statistics are given by Phalen in Table 7. 



