The larger percentage of potash consumed by the world is used in commercial fertilizers, although considerable is made into chemi cals for the arts and medicine and for explo sives. In the latter case, however, it is not as important as it was formerly, as the high explosives do not contain it. Potash is essential to plant growth and in agriculture is rapidly depleted from the soil, and must be returned in fertilizers. It also has an important stimulating effect on soils naturally deficient in this com ponent. The production of potash-bearing ma terial in the United States in 1917 was 126,961 short tons, containing an average of 26.4 per cent of 1C20, an equivalent of 32,573 short tons of potash; that is, 13.6 per cent of the normal consumption of the United States. This pro duction was three times the amount produced in 1916 and 30 times the amount in 1915. Dur ing the war the price rose from the normal rate of 50 to 75 cents a unit to about eight times as much. The average for 1917 was $4.26 per unit or a total of $13,791,922. The unit is 1 per cent K20 per ton. The production in 1917 is shown in table below.
About 63 per cent of the total output was produced from brines in lakes, mainly from those in the Sand Hill district of western Nebraska and from Searles Lake in California. From the Nebraska lakes a total of 61,053 tons of crude potash material was marketed in 1917; equivalent to 14,588 tons of pure potash. The residue resulting from the burning of kelp, the great sea weeds on the Pacific Coast, is a potential source, but as the raw material con tains 90 per cent of water the expense of handling and drying it is great. The char or clinker carries from 20 to 30 per cent of K20 and valuable by-products, including iodine, help defray the otherwise prohibitive cost of treat ment. Charred molasses residue at alcohol dis
tilleries yields considerable potash, while waste liquor from one of the beet sugar processes is a minor source. Potash is extracted from the mineral alunite mined near Marysvale, Utah, the potassium sulphate being made soluble by calcining. Flue dust from cement mills is an important source, with constantly increasing product as mills utilize more material rich in potash and make provision to catch flue dust. The dust is leached and a high grade potassium sulphate is obtained by evaporation. In 1917 eight mills produced a total of 1,621 tons of actual potash. A very large amount of potash is given off as vapor in fumes from blast fur naces, but no provision is made to collect this material. The present small output (1917) re ported from three steel companies was recovered from the dust which collected in flues and stoves. The loss of potash in the furnace gases is not less than 22 pounds for each ton of iron produced. It is believed that if the large furnaces installed suitable flues the sup ply would be sufficient for all domestic demands and at very low cost. A constantly increasing supply is derived from the old-fashioned source of leaching wood ashes. Considerable potash is extracted from the crude Chilian nitrate of soda. See POTASSIUM.
In 1918 production increased to 192,587 tons of products, containing 52,135 short tons of 1C20. The producing capacity of American potash plants at end of 1918, classified according to sources of raw materials, is estimated roughly as follows: This quantity is about 40 per cent of our ordi nary consumption in pre-war times and the out put that may be maintained if the demand con tinues and the industry is not crippled by for eign competition.