CHEMICAL ANALYSES. 278 



of reh from vsar lands in the United Provinces are given by 

 J. W. Leather. 1 The deposit consists of the four salts, sodium 

 carbonate, bicarbonate, sulphate, and chloride in very varying 

 proportions, and the analyses are very similar to those given above 

 of the efflorescent salt from the Sind dhanch. W. Center 2 discusses 

 the mode of formation of reh and inclines to the view that the alka- 

 line carbonates are derived from rock decomposition, the sodium 

 being derived from such minerals as felspar which are acted on by 

 water with carbon dioxide in solution. 



Efflorescent salts of a very similar type are found in the desert 

 regions of the United States, where they have been investigated 

 very carefully by the scientists of that country. Analyses and a 

 resume of the various hypotheses of their formation are given by 

 F. \V. Clarke. 3 Clarke explains the alkalis of the Lahontan waters 

 in Nevada as a concentration of leached material from the igneous 

 rocks of the neighbourhood— a view that may be compared with 

 that of W. Center in the case of reh. La Touche and Christie, 4 in 

 their account of the alkaline lake at Lonar in Berar, adopt a similar 

 explanation. The chief difficulty in the way of accepting this 

 view is the fact that in all these alkaline deposits, large quantities 

 of chloride are associated with the alkali. It is not easy to account 

 for the chloride as due to the breaking down of rock-forming minerals 

 since, as W. Center and others have pointed out, the percentage of 

 chlorine in the different classes of rock is extremely small. 



Those authorities who have explained the origin of the carbonate 

 in the maimer outlined above have found it necessary to seek a 

 different origin for the chloride, which the majority appear to regard 

 as ultimately derived from the sea. The necessity of supposing 

 different origins for these two associated salts is a stumblmg-block 

 in the way of full acceptance of these views. 



Accordingly other hypotheses have been put forward, which arc 

 not open to this objection. A view developed by T. Sterry Hunt 

 E von Kvassay, 6 E. W. Hilgard,' and by G. Schwemfurth and 

 R. Lewin, 8 supposes that the sodium carbonate of alkaline lakes 

 i "Investigation on Usar Land in the U. P.," Allahabad, 1914. 



*Rec. 0. S. I., XLI, p. 200 



' Am. J. Sci., 2nd Ser., vol. 28, p. 170. 



• Jahrb. K.-k. Qeol. Reichmnst., 18/0, p. 427. 



' Am. J. Sci.. 4th Ser., vol. 2, p. 123. 



s Zeits. QesM. Erdkunde, vol. 33, 1898. p. 1. 



