348 Dr. A. Holmes — Non-German Sources of Potash. 



been formed to extract potash from the Leucite Hills, 1 but little 

 progress has as yet been reported, while in Italy the problem is still 

 a subject of active research. 



Glauconite. — British " greensands " rarely contain more than 

 4 per cent of potash, and consequently they fail to provide a 

 practicable source. In the United States, however, potash has 

 already been successfully recovered from glauconitic sands and marls. 

 A narrow belt of Upper Cretaceous greensand extends from Sandy 

 Hook to Virginia, and in many parts of New Jersey glauconite is so 

 abundant that the air-dried sediment contains from 6 to 7 per cent 

 of K 2 0, three-quarters of which can be liberated by the process 

 adopted. Glauconite has the advantage over felspar of being 

 practically free from alumina and soda. To remove the latter 

 impurity from potash concentrates is somewhat troublesome, and 

 the alumina, if extracted by digestion, requires so high a proportion 

 of water that the expense becomes prohibitive. In the case of 

 glauconite a similar method of treatment can be applied at a 

 comparatively low cost. The process involves digesting with high- 

 pressure steam a mixture of the finely-ground raw material with 

 lime. The resulting filtrate contains potash with little impurity 

 (80 per cent KOrl on evaporation), while the residue contains 

 cementitious constituents, and is utilized in the manufacture of 

 bricks and tiles. 



Alunite. — This mineral, the composition of which may be 

 represented by the formula K[Al(OH) 2 ]g(S0 4 ) 2 , is readily decomposed 

 by calcination; sulphuric acid is driven off, together with all the 

 water, leaving a residue of soluble K S0 4 and insoluble alumina. 

 Although alunite has been generally used as a source of alum, in 

 recent years high-grade potassium sulphate has been prepared from 

 it, the first successfully operated plant having been established in 

 Utah. Alunite occurs in veins, and disseminated through the 

 adjacent rocks, in certain volcanic regions, where it is produced in 

 association with propylitization, by the action of hydrothermal 

 emanations containing sulphuric acid or its constituents. The chief 

 localities where it is actively mined are Marysvale, Utah ; Goldfield, 

 Nevada; Bullah Delah, New South Wales; La Tolfa, Italy ; and 

 Almeira, Spain. 



Pecoveky of Potash from the Dust of Cement Kilns. 

 Several years ago the fruit-growers in the vicinity of the 

 Riverside Portland Cement Company, California, complained that 

 the dust from the kilns caused serious damage to their crops. In 

 consequence the Compamr took steps to abate the nuisance, and 

 installed an electrical precipitation plant to settle the dust. Hoping 

 that the dust might be of some economic value, and so might 

 contribute towards the cost of its collection, analyses were made, 

 and it was found that it contained 10 per cent of potash. Expecta- 

 tion was thus amply fulfilled and the recovery of potash was at once 

 developed as a profitable by-product. 3 



1 A. H. Eogers, Met. & Chem. Eng., vol. xv, p. 387, 1915. 



2 L. Bradley, Journ. Ind. & Eng. Chem., vol. x, p. 804, 1918. 



