230 CALIFORNIA ALKALINE AND BORACIC LAKES. 



its centre to the depth of sixty feet afforded a certain amount of the salt 

 throughout its whole extent. 



The crystals thus occurring are most abundant near the centre of the 

 lake, and extend over an area equivalent to one-third of its surface ; they 

 are, however, also met with in smaller quantities in the muddy deposit of 

 other portions of the basin. The largest crystals, some of which are con- 

 siderably above a pound in weight, are generally inclosed in a stiff blue 

 clay, at a depth of between three and four feet; and a short distance above 

 them is a nearly pure stratum, from two to three inches in thickness, of 

 smaller ones ; in addition to which crystals of various sizes are disseminated 

 through the blue clayey deposits of which the bottom consists. 



Besides the borax thus existing in a crystallized form, the mud itself is 

 highly charged with that salt, and, according to an analysis by Dr. Oxland, 

 affords, when dried, in those portions of the lake which have been worked 

 (including the inclosed crystals), 17.73 per cent. Another analysis of an 

 average sample, by Mr. G-. E. Moore, of San Francisco, yielded 18.86 per 

 cent, of crystallized borax. In addition to this the deposit at the bottom of 

 the other portions of the basin, although less productive, still contains a 

 large amount of borax. 



Water collected from Borax Lake, in September, 1863, was found by Mr. 

 Moore to contain 2401.56 grains of solid matter to the gallon, of which about 

 one-half was common salt, one-quarter carbonate of sodium, and the re- 

 mainder chiefly anhydrous borax, equal to 535.08 grains of crystallized salt 

 to the gallon. Traces of iodine and bromine were also detected. A sample 

 of water taken from the interior of a coffer-dam sunk in the middle of the 

 lake, and which has been allowed to fill by percolation from the bottom up- 

 ward, was found to be more concentrated, yielding 3573.46 grains of solid 

 matter to the gallon, but it contained the same ingredients, and in nearly 

 the same proportions as the water from the lake itself. When evaporated to 

 dryness, this water yields a considerable quantity of finely-divided carbon, 

 resulting from the various organic bodies which have been dissolved in it. 



Mud from the bottom of Borax Lake is in high repute among the local 

 Indians as ah insecticide., and is used in the following way: The head of the 

 patient is thickly j)lastered with mud, which is well rubbed in, and then al- 

 lowed to become perfectly dry; when dry it is removed by rubbing between 

 the hands, and with it disappears the colony of parasites. Ordinary clay 

 is, under pressure of circumstances, sometimes employed for this process 

 of shampooing, but when alkaline or boracic mud is available, it is con- 

 sidered more efficacious. 



When this locality was visited by me in 1866, borax was manufactured 

 exclusively from the native crystals of crude salt, while the mud in which 

 they were found was returned to the lake after a mechanical separation of 

 the crystals by washing. The extraction of boracic mud was affected by 

 the aid of sheet-iron coffer-dams. The only apparatus employed consisted 

 of a raft, covered by a shingled roof, provided with an aperture in its cen- 



