CHAPTER XXVI
POTASH
By Hoyt S. Gale and A. W. Stockett
NATURE AND USES OF POTASH
The term potash is commonly used to designate any of the salts of the element potassium, particularly those soluble in water, which are largely used in agriculture and manufacturing. The element potassium is widely distributed as a component of rocks, soils, and vegetable and animal substances, but large quantities of potassium salts in forms suitable for the uses of man have been found in only a few places. Ashes of wood, which were formerly the principal source of potash in commerce, now supply an inconsiderable part of the world’s requirements. Since 1860, the principal, in fact almost the only, commercial source of potash salts has been the immense deposits in northern Germany. The crude potassium salts obtained from these deposits by mining operations are used either as fertilizer in the form in which they are taken from the ground, or are purified by crystallization or manufactured into various compounds of potassium needed for both agriculture and other industrial uses.
Use in agriculture as an ingredient of the so-called artificial or chemical fertilizers accounts for 90 per cent. or more of the world’s consumption. Potassium is not only one of the ten or more chemical elements essential to plant life, but of these ten it is one of three that frequently become so lacking in soils that the yield of crops is not profitable. Even if potassium exists in soils, it may be and often is present in some form not readily available for plant use, so that the addition of fresh, readily water-soluble salts of potassium shows prompt reaction in stimulating the growth of the crop. In a general way potash is supposed to supply a necessary plant food, that strengthens the stalk and fills the kernels of the growing plant. Also it is a general belief that some destructive plant diseases, such as blight and rust of cotton and potatoes, are largely favored by improper nutrition as well as by poor physical condition of the soil, for which potash seems to be a specific. Thus the so-called potash industry, by which is meant the mining and marketing of the principal or commonest compounds of potash, is based chiefly on use in agriculture.
The other uses of the salts of potassium are many and diverse. Most of the potassium salts have properties similar to the corresponding salts of sodium, and for most industrial purposes the salts of these two elements may be interchanged, a generalization which does not, however, apply to any extent whatever to the agricultural application of potassium. Some industrial preferences for the potassium salt depend on more favorable physical properties of the potassium over the sodium salt, such as a less tendency of the potassium salt to absorb moisture from the air. Other preferences depend on slight chemical differences, as for instance a somewhat greater solubility, which renders the purification of the potassium salt more easy. During the scarcity and high prices of the wartime period many substitutions have been made, which either directly or by some modification of practice are now proving so satisfactory that they will probably be continued.
One of the most urgent demands for potash has come from the match manufacturers. Potassium chlorate is an important ingredient of most matches, and this use consumes a surprisingly large amount of potash. Certain varieties of glass, especially cut glass tableware (flint glass) and some optical glass, are made from potash, generally in the form known as glass-makers’ carbonate. Most soap is made from soda, but potash (as caustic or hydroxide) is used for some of the finer grades, such as shaving, toilet, and shampoo soaps, especially the liquid forms. Caustic potash has had a considerable use in laundries, and for the scouring or washing of wool. The old form of black powder was made from potash as potassium nitrate or saltpeter; hence the commonly assumed military importance of potash. Black powder, though now largely superseded by modern high-explosive powders, still has a relatively small though nevertheless important application in modern warfare. There are other uses, which, though requiring a small total amount, include some important requirements, among these being the medicinal or pharmaceutical, tannery, dye, photographic, electroplate, and metallurgical needs.
GEOGRAPHICAL DISTRIBUTION
The great deposits of potash in northern Germany underlie an extensive area in the Prussian provinces of Saxony, Hanover, and in the duchies of Anhalt and Brunswick. The most important mining regions lie in an area practically encircling the Harz Mountains, 75 to 150 miles southwest of Berlin, and 100 to 150 miles south to southeast of Hamburg. This area is outlined more exactly on the accompanying index map ([Fig. 14]).
The field originally opened at Stassfurt has since been explored by deep boring and developed by the sinking of mining shafts, with the result that there has now been outlined an estimated reserve of 20,000,000,000 metric tons of crude potash salts, which at the present rate of the world’s consumption should be sufficient to last almost 2,000 years. Thus for all practical purposes the field may be considered as inexhaustible.
