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TEE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



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 

 BaDk." It is some six or seven acres in extent, 

 and consists of a much-decomposed volcanic 

 rock traversed by innumerable fissures, which 

 has become almost covered by a large accumula- 

 tion of sulphur. 



From the fissures steam and gas are constant- 

 ly issuing, and over and through the mass large 

 quantities of sulphur have been deposited in such 

 a way that at a short distance the whole bank 

 appears to consist of this substance. Into some 

 of these cavities a pole may be inserted for a 

 distance of several feet, and they are often lined 

 with stalactites and beautiful crystallizations of 

 sulphur. 



Sulphur is being constantly deposited, and its 

 deposition is attended by the evolution of car- 

 bonic and boric acids. The gaseous matters 

 issuing from these crevices appear to be the 

 agency by which the various substances now de- 

 posited in the cavities have been brought to the 

 surface. Sulphur is deposited on the sides of 

 the various fissures either in the form of crystals 

 or as amorphous, translucent masses of a beauti- 

 ful yellow color. It is sometimes intermixed with 

 cinnabar, the presence of which was first discov- 

 ered by Dr. Oxland ; but more frequently with 

 minute cubical crystals of iron pyrites. Pul- 

 verulent silica, blackened by some hydrocarbon 

 resembling coal-tar, is also frequently observed. 



On the sides of the cavities colloid silica is found 

 coating chalcedony and opalescent quartz in the 

 various stages of formation, from the gelatinous 

 state to that of the hardest opal. The indurated 

 material is sometimes colorless, but is more fre- 

 quently permeated by cinnabar and iron pyrites, 

 or blackened by the tarry matter before referred 

 to. Cinnabar is also found in laminae, and occa- 

 sionally even in veins and concretionary masses 

 of considerable thickness. 



In addition to being employed as a source of 

 sulphur, this deposit has been worked for quick- 

 silver, and has produced large quantities of that 

 valuable metal. 



On the shore of Clear Lake, near the sulphur- 

 bank, is a hot spring, of which the outlets, even 

 when the water is low, are partially beneath the 

 lake, so that the amount flowing from it can- 

 not be ascertained. Hot water, however, rises 

 through the sand at various points extending over 

 a considerable area. A specimen of water col- 

 lected by Mr. Moore from this spring was found 



by him to contain 184.62 grains of common salt, 

 76.96 grains of bicarbonate of sodium, 36.37 

 grains of free carbonic anhydride, 103.29 grains 

 of borax, and 107.76 grains of bicarbonate of 

 ammonium, in an imperial gallon ; besides silica, 

 alumina, and traces of various other substances. 



Prof. Whitney remarks with regard to this 

 spring : " The most extraordinary feature in the 

 above analysis is the very large amount of ain- 

 moniacal salts shown to be present in this water, 

 in this respect exceeding any natural spring-wa- 

 ter which has ever been analyzed. Mr. Moore 

 thinks that, as in the case of the boracic-aeid 

 waters of Tuscany, ammoniacal salt may be sep- 

 arated and made available for economical pur- 

 poses. This locality is worthy of a most careful 

 examination, to ascertain how considerable a flow 

 cf water can be depended on." 1 



Dr. A. Blatchly, of San Francisco, in speak- 

 ing of the geyser group of quicksilver-mines, 

 says : " Nearly all these veins contain iron in 

 considerable amounts, frequently in sufficient 

 quantities to constitute an ore of iron. Gold, 

 silver, and copper, are also frequently constitu- 

 ents of these lodes, and occasionally chrome-iron 

 in considerable quantities. But, so far as is 

 known, in no instance have the precious metals 

 been sufficiently abundant to pay for the expense 

 of extraction. 



" Bitumen is found in nearly all these veins, 

 sometimes a deposit of a gallon or two in one 

 cavity. 



" Thermal springs are numerous throughout 

 the whole quicksilver-region, and the uniformity 

 of their occurrence leads prospecters to the be- 

 lief that there is an intimate relation between the 

 causes which generate thermal springs and pro- 

 duce deposits of cinnabar, and that where one is 

 found the other may probably occur in the vicin- 

 ity." * 



On the eastern slope of the Sierra Nevada, 

 near Walker's Pass, borax is found in what ap- 

 pears to be the bed of an ancient lake, large 

 crystals of this substance having been met with 

 in a hardened mud, exactly resembling those 

 found in the blue clay of Borax Lake. By far 

 the largest amount of borax is, however, ob- 

 tained from the indurated mud, where it exists 

 in common with other salts. This mud, from 

 which borax is separated by lixiviation, contains 

 about half its weight of that salt, and is a light, 

 clay-like body, having a strongly saline and al- 



i " Geological Survey of California," p. 100. 

 2 " Mineral Resources west of the Rocky Mountains, 1 ' 

 1S75, p. 176.— Raymond. 



