346 Br. A. Holmes — JSf on-German Sources of Potash. 



industry had long before the war fallen to very small dimensions, 

 and even since 1914 it has not been appreciably revived. The home 

 contribution of potash during the war from kelp l was, indeed, barely 

 sufficient to supply the KC10 3 required for the manufacture of 

 matches. 



Along the Pacific coast the kelp industry has developed on an 

 enormous scale under the impetus of the demand for acetone and 

 potash that arose early in the war. Giant seaweeds are harvested 

 directly from the sea by floating mechanical reapers. After the 

 weed is dried and burnt, the resulting ash contains salts equivalent 

 to about 15 per cent of K 3 0. As a method leading to potash 

 recovery alone — that is, without the collateral separation of by- 

 products — this process was found to be wasteful, and even when the 

 ash was sold directly as a fertilizer it was not found possible to 

 compete with other sources of supply. Consequently more economical 

 methods of treatment have been devised, the most successful being 

 that in which acetone is prepared as the main product, with potash 

 as a by-product. At San Diego the seaweed is fermented in large 

 bins, and the resulting solutions (containing crude acetic acid with 

 KC1 and iodine compounds) are collected. Calcium acetate is formed 

 by neutralizing the acid with limestone, and by its ignition acetone 

 is formed. Meanwhile potassium chloride and iodine are concentrated 

 in the residual liquors, and are ultimately separated in a crude state. 

 The three products taken together have provided satisfactory profits 

 imder war conditions, but the future stability of the industry is less 

 certain, especially as, in common with Searle's Lake, the site of 

 production is far removed from the principal centres of demand. 2 



Other Organic Sources. — The fact that 90 per cent of the potash 

 used in Great Britain is devoted to fertilizing purposes, is clearly an 

 indication that the plants which absorb potash from the soil may 

 themselves be utilized for its subsequent replenishment. Among 

 important ci'ops, flax and potatoes in particular require large 

 quantities of potash for continued growth. It is, however, not 

 possible to produce potash economically from waste vegetation except 

 as a by-product in already established industries. Even in the 

 lumber camps of Canada the wood-ash from saw-mills waste contains 

 insufficient potash to justify its collection and treatment, and its 

 only value is as a local fertilizer applied to the land directly. 3 

 In Belgium and Italy potassium salts (K„C0 3 , KC1, and K 2 S0 4 ) are 

 recovered from the residual liquors left after the treatment of 

 molasses in beet-sugar factories. In the Caucasus district there was 

 formerly a considerable local potash industry dependent on the 



1 The ash or slaggy matter that remains when seaweed is burnt in a kiln for 

 six or eight hours is called kelp ; but in the United States the weed is kelp, 

 and the product kelp-ash. The ash, as obtained on the west coast of 

 Scotland, contains about 18 per cent of KC1 and 13 per cent of K 2 S0 4 . 



2 Since writing this paragraph I have been informed (April 24, 1919) by the 

 Controller of Potash Production that most of the American kelp recovery 

 plants have been shut down since the effective termination of the war. See 

 also Journ. Soc. Chem. Ind. (June 15, 1919) for a recent statement of the 

 potash position in the United States. 



3 The World's Supply of Potash, Imperial Institute, 1915, p. 25. 



