252 Br. A. Holmes — Non-German Sources of Potash. 



of the same order, must be mainly present in organisms. It is well 

 known that potassium salts are preferentially adsorbed by colloidal 

 and physically analogous substances from solutions that percolate 

 through soils, and from the latter they are taken by plants, and 

 thence by animals. Of the potash that reaches the sea a high 

 proportion is similarly abstracted by seaweeds, while another 

 considerable fraction is adsorbed by ferruginous and siliceous matter 

 to form glauconite. Without going into further detail, the circula- 

 tion of potash from its original magmatic sources is summarily set 

 forth in the following scheme, with a view to indicating the deposits 

 from which extraction is economically practicable, or likely to 

 become so if need arose : — 



Rocks rich in 

 Leucile, Orthaclase, 

 Microcline, or Micas 



-MAGMAS. 



IGNEOUS 

 ROCKS 



MAGMATIC ii l ™ iUV ?™ 

 EXUDATIONS \ ty , De P<"*{ s f™>»> 

 ^s [Volcanic Springs 



SEDIMENTARY ROCKS 



I. 



Olauconitic[ 

 Deposits J 



ORGANIC ACCUMULATIONS 



(Seaweed (Kelp) 

 Vegetation 



Animal 

 Refuse 



(Nitrates) 



Dust from Cement Kilns 



Flue Dust from Blast Fur>iaces 



/ Saline Deposits. 



In addition to the extensive German salt-fields, 1 generally referred 

 to as the Stassfurt deposits, there are at least half a dozen areas 

 where beds of potassium salts are associated in workable quantities 

 with saline formations. Three of these, in Alsace, Spain, and 

 Abyssinia, are of outstanding importance. In Galicia, Lower 

 Miocene beds of kainite and sylvite are mined at Kalusz, but as the 

 output is insufficient to supply the local demand, these deposits are, 

 for us, of minor interest. 2 Numerous potash-bearing seams have 

 been discovered in the mines of the Salt Eange of India. 3 Their 

 commercial development, however, has been restricted by the 

 irregularity of the potash and the abundance of sulphates, and at 

 present their exploitation has scarcely passed the prospecting stage. 

 In Chile there are extensive salt deposits lying to the east of the- 

 nitrate fields, and one of these, the Pintados Salar, which is skirted 



1 J. W. Gregory, Trans. Geol. Soc. Glasgow, vol. xvi, p. 12, 1916. 



2 Zeit. fur das Landwirtschaftliche Versuchswesen, vol. xviii, p. 892, 1914. 



3 W. A. K. Christie, Eec. Geol. Surv. India, vol. xliv, p. 243, 1914. 



