CALIFORNIA ALKALINE AND BOBACIC LAKES. 231 



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 tre about fifteen feet square, above which were hung, by suitable tackle, four 



coffer-dams, each six feet square in horizontal section, and nine feet in depth. 

 This raft, or barge, was successively moored in parallel lines across the sur- 

 face of the lake, and at each station the four dams were sunk simultaneously 

 by their own weight into the mud forming the bottom. 



"When they had thus become well imbedded, the water was baled out, 

 and the mud and crystals removed, by means of buckets, into rectangular 

 washing-vats, into which a continuous stream of water was introduced from 

 the lake by Chinese pumps, the contents being at the same time constantly 

 agitated by the aid of wooden rakes. In this way the muddy water contin- 

 ually flowed off, finally leaving a certain amount of crude borax at the bot- 

 tom of each tank ; this was purified by recrystallization. From the density 

 acquired by the 70,000 gallons of water dail}^ employed for this purpose, it 

 is evident that only about one-half of the borax existing in the form of 

 crystals was thus obtained, while the mud was again returned to the lake. 



Instead of the coffer-dams, a small hand-dredging machine, worked 

 like the former, by Chinese labor, was subsequently introduced; but the 

 mud brought up by it was subjected to the wasteful process of washing be- 

 fore described. 



The crystals of crude borax thus daily obtained amounted to about 

 3,000 pounds ; these were dissolved in boiling water, and recrystallized in 

 large lead-lined vessels, from which the purified salt was removed to be 

 packed into boxes, each containing 114 pounds, in which it was forwarded 

 to San Francisco. The loss of weight experienced in the process of purifi- 

 cation amounted to about thirteen per cent. 



Shortly after my visit in 1866, the manufacture of refined borax at Big 

 Borax Lake was suspended, and I am not aware whether it has been re- 

 sumed, but the works do not appear to have been in operation in 1874. 



Little Borax Lake covers an area of about thirty acres, and is usually 

 dry during the months of September and October ; it is then covered by a 

 white crust, which is collected by Chinese laborers and carried to the works, 

 where it is refined by recrystallization. Ulexite, a double borate of sodium 

 and calcium, is brought to this place from Wadsworth, in the State of Ne- 

 vada — a great distance, with several trans-shipments— to be treated at these 

 works; it appears that on account of the jDresence of carbonate of sodium, 

 and the cheapness of fuel, this can be done more cheaply here than in Nevada. 



Clear Lake is a large and picturesque sheet of water, twenty-five miles 

 long, by about seven wide, surrounded by mountains, which in many places 

 rise abruptly from the water's edge. Boat-life on this lake is delightful; 

 the water is smooth, there is usually a sufficient breeze for sailing, and should 

 it fall calm, an Indian can always be hired to row. 



Lying about a mile beyond the ridge which borders Borax Lake on the 

 northeast, and at the foot of a shorter arm of Clear Lake, which extends off 

 to the southward parallel with the larger one, is an interesting locality, 

 known as the "Sulphur Bank." It is some six or seven acres in extent, and 



