CHEMICAL WORK. 119 



days. It gathers other materials as it flows, taking them from the soil and 

 its organic decompositions, and from rocks or minerals, and especially where 

 decompositions are in progress. It finds soda and potash in rocks containing 

 feldspars ; lime and magnesia, in limestones and also more or less in many 

 other rocks, fragmental and crystalline ; and various other materials in these 

 and other rocks. Among the materials gathered up, the chief are calcium 

 carbonate ; salts of iron ; magnesium, sodium and potassium carbonate, sul- 

 phate or chloride ; calcium chloride; humus acids from the soil; and carbonic 

 acid from the soils and other sources ; besides, more sjjaringly, aluminum 

 sulphates and lithium salts. Besides the gas carbonic acid, the waters often 

 xeceive and discharge hydrogen sulphide and nitrogen, and sometimes the 

 gases hydrogen and oxygen. The gatherings depend on the kinds of rocks 

 washed by streams, both those of the surface and those of subterranean 

 source. It was long since recognized that, through the gathering action of 

 fresh waters, a lake without outlet might become saline, like the sea. 



The desert and semi-desert regions of the world often illusti-ate through 

 the eiflorescences that exist over the surfaces of old lake basins, as well as 

 the salts in the waters of lakes, what solvent work the waters have done. 

 The Great Basin in the west has been studied with reference to this subject 

 by King, Gilbert, Russell, and others. The moisture below comes up by 

 capillary action ; and, as evaporation above is almost constant, owing to the 

 excessive dryness and heat (90° F. the mean over part of it for July), so also 

 the production of the salts is in constant progress. The most abundant are 

 common salt (XaCl), sodium carbonate and sulphate, with often calcium 

 carbonate, and borates. 



From one of two samples of the saline deposits from the Lahontan region analyzed "by 

 Dr. T. M. Chatard were obtained, as cited by I. C. Eussell, 72-69 per cent of sodium carbo- 

 nate (Na20.C02), 17-49 of sodium sulphate (NaaO.SOj), 4-15 sodium borate (Na20.B^0g), 

 2-53 sodium chloride (NaCl), 1-18 potassium chloride (KCl), and 1-96 silica. In the 

 other : 9-06 NaoO.COo , 27-05 NaaO.SOg, 1-00 NaoO.B.Og, 59-32 NaCl, 1-39 KCl, and 2-18 

 Si02. In deposits of the dried-up Sevier Lake, south of the Great Salt Lake, Dr. 0. 

 liOew obtained, as reported by G. K. Gilbert, (1) from those of the center of the lake: 

 sodium sulphate 87-65, sodium carbonate 1-08, sodium chloride 2-34, with water 8-90 = 

 99-97 ; (2) from the middle or 3d layer of those of the margin, sodium sulphate 83-79, 

 sodium chloride 13-84, magnesium sulphate 1-33, potassium sulphate 0-26, with water 0-78 = 

 100; from a layer overlying the last, (4th layer) sodium sulphate 2-71, sodium chloride 

 S8-49, magnesium sulphate, potassium sulphate 0-11, water 3-40 = 100. The above are a 

 few of the published analyses. These saline materials were once in solution in lakes of 

 the region that are now dried up. 



Salt lakes are in some cases remnants of the ocean that once covered the 

 land. But in the Great Basin, according to Gilbert, the saline ingredients 

 have come from the soil and rocks of the region. 



Mineral springs, or sources of water holding mineral ingredients in solu- 

 tion, are hence universally distributed. They include " pure " waters as well 

 as the so-called "mineral waters." The latter contain some mineral salt 

 generally in sufficient quantities to affect the taste ; and they are most 



