Mat 



1922] 



SCIENCE 



479 



It is, however, interesting to note that the 

 remarkably well delined right-handed or east- 

 ward shifting of many radial streams that flow 

 down the gentle slope of the great alluvial fan, 

 known as the plateau of Lannemezan, at the 

 northern base of the Pyrenees — beautifully 

 shown on the 1 :80,000 map of France, sheets 

 216, 217, 227, 228, 229, 239, 240, and 241— 

 has been explained by Marchand and Fabre- 

 not as a consequence of the earth's rotation but 

 as a result of stronger action of rain driven 

 by westerly winds ; so that here it is the valley 

 sides facing against the wind that are the 

 steeper, while on Long Island the steelier val- 

 ley sides face with the winds. It is difficult to 

 understand just how either explanation works, 

 but in any case the relation of the steep valley 

 sides and the prevailing winds is unlike in the 

 two examples. 



W. M. Davis 



Cambridge, Mass., 

 April 2, 1922 



POSSIBLE CAUSE OF THE RED COLOR OF 

 POTASH SALTS 



The red color of certain potash and ordinary 

 salt deposits has been observed in many parts 

 of the world, for example, in the Indian, Ger- 

 man, Alsatian and Spanish potash deposits, in 

 Nova Scotia, west Texas and doubtless in other 

 places that the writer has not heard of. The 

 same, though a less intense coloration has been 

 observed by the writer in the surface salt and 

 strong brine standing in the trenches and in 

 pools along the margin of the salt ponds where 

 solar salt is made along the shore ef San Fran- 

 cisco Bay, California. It has been noted at 

 Searles Lake in the same state. I am told that 

 the same red color exists also in the solar salt 

 ponds on Turks Island. It is undoubtedly of 

 common occurrence in many places where solar 

 evaporation results in producing salt, either 

 naturally or artificially. 



The red color associated with certain potash 

 minerals is so common that it has come almost 

 to be regarded as a means of identifying cer- 



- Les erosions torrentielles et subaeriennes sur 

 les plateaux des Hautes Pyrenees. C. R. Congr. 

 Soc. savantes, 1900. 



tain of them, for example, the mineral carnal- 

 lite in the German deposits. There is however, 

 as chemists well know, nothing inherent in the 

 composition of carnallite (KCl.MgCL.eHjO) 

 to cause this red tint and indeed the normal 

 color of the pure double salt should be the same 

 as that of ordinary white rock salt. 



There has been a great diversity of opinion 

 as to the origin of the red color in solar salt 

 and bitterns where solar evaporation is in pro- 

 gress. That it is not necessarily due to the 

 presence of iron appears evident from the ob- 

 servations of George Lunge, the expert on sul- 

 phuric acid manufacture. Lunge^ states that: 



The red color exhibited by many alkaline 

 salt lakes, which is often also apparent in the 

 salt deposits, is ascribed by Payen^ to the pres- 

 ence of small crustaceans, Artemia Salina Leach 

 (Cancer salinus Linne), which appear in large 

 masses when the water has attained a density of 

 1.16, and which are of a gray or greenish color; 

 on further eoneentration to a specific gravity of 

 1.21, they die and form a red froth at the sur- 

 face. ... I, for my part, must decline to accept 

 the assumption that the red color is regularly 

 caused by the presence of Artemia or other ani- 

 mal organisms, if it is ever due to that cause; 

 for the samples of red water which I had myself 

 taken from the lakes of the Wade Atrun have 

 preserved that color during the many years I have 

 kept those samples. The red filtrate shows noth- 

 ing under the miscroscope; the color is at once 

 discharged by adding nitric acid or hypoohloride 

 and hydrochloric acid and is evidently caused by 

 organic substances present in solution. There is 

 no iron present. 



Recent studies made in the U. S. Bureau of 

 Fisheries, Department of Commerce, connected 

 Avith the reddening of salt fish are of interest 

 and importance in this connection. They are 

 also of economic value in view of the consider- 

 able annual losses to the fish industry caused 

 by salt fish developing a red color when stored 

 under moist conditions. The Bureau investiga- 

 tions, which were conducted by W. W. Browne^, 



' Lunge, Geo., Sulphuric Acid and Alkali, Vol. 

 2, pt. 1, p. 58, 1909. 



2 Payen, Anselme, Annales chiin. et pliys., 2d 

 ser., Vol. 65, p. 156, 1837. 



3 Bureau of Fisheries, Document 896, 1920, pp. 

 27-28. 



