Dr. A. Holmes — Non-German Sources of Potash. 349 



During the lust two years experimental plants have been run by 

 certain British firms for the same purpose, and although the raw- 

 materials generally contain only a very small proportion of potash, 

 the quantities of cement manufactured are so great that a considerable 

 output of potash is potentially available from this source. Un- 

 fortunately, no authoritative statement has yet been issued of the 

 results of the processes so far tested. As a further development, 

 the scope of the experiments has recently been extended to test the 

 suggestion that potash-felspar might advantageously be substituted 

 in part for the clay used as a raw material. "When one part of 

 orthoclase is intimately mixed with three parts of calcium carbonate, 

 and the mixture heated to 1,300°-1,400° C. for about an hour, potash 

 is volatilized, and the residual clinker corresponds in composition with 

 that of Portland cement as normally prepared. Similarly, when the 

 mixture is digested with steam at a pressure of from ten to fifteen 

 atmospheres, a solution is obtained containing as hydroxide 90 per 

 cent of the potash originally present in the charge, and the residue 

 is again a Portland cement clinker. 1 



There can be little doubt that the cement industry could, if 

 necessary, supply very substantial quantities of potash by developing 

 along these lines; but on the other hand the incentive of urgent 

 national need having now passed, and the attraction of high prices 

 being but temporary, it is unlikely that the extraction of potash 

 from felspar by this means will become a peace industry. 



Blast Furnace Flue-dust. 



Among the various methods exploited in Britain with a view to 

 developing our home resources, the recovery of volatilized potash 

 from blast-furnace flue-dust and gases has emerged as the most 

 fruitful. Potash is present in small quantities in all the materials 

 charged into the furnaces, iron-ore being regarded as the principal 

 source. Iron-ores vary greatly in their potash content, the figures 

 ranging from 0*2 to 2-5 per cent. The ash from coal contains 

 from 0-2 to 0-7 per cent, but it is possible that these figures do 

 not adequately express the potash content of the original coal, as 

 they do not include potash that may have been volatilized during 

 combustion. That coal may possibly supply more potash than is 

 usually recognized, is indicated by the fact that in certain experi- 

 mental runs the potash balance-sheet actually revealed a greater 

 recovery of potash than the amount estimated to be present in the 

 raw materials fed into the furnace. Generally, however, the 

 balance-sheet shows a more or less marked deficit. 2 



Since the early part of 1915 a series of valuable experiments have 

 been carried out by Mr. Kenneth M. Chance 3 of the British Cyanides 

 Co., Ltd., and Mr. Lennox Leigh, of the North Lincolnshire Iron 

 Co., Ltd. It was found that the volatilization of potassium as 

 chloride could be greatly increased by adding to the charge a small 



1 W. H. Boss, Journ. Ind. & Eng. Chem., vol. ix, p. 469, 1917. 



2 E. A. Berry & D. N. McArthur, Journ. Soc. Chem. Ind., vol. xxxvii, p. T 1, 

 1918. 



3 Journ. Soc. Chem. Ind., vol. xxxvii, p. T222, 1918. 



