Potash
3 of the 6 encyclopedias on this shelf carry an entry for Potash. All 3 are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
Important: Safety Warning
This page directs the use of hazardous substances — such as benzine, gasoline, lye, or strong acids — for household tasks. These materials are highly flammable, corrosive, or poisonous, and the practices described have caused fires, burns, and poisonings.
In addition, this page presents medical treatment from an era before modern medicine. The remedies described are ineffective against the conditions named, and some of the ingredients or doses are harmful. Do not use them to treat any illness; consult a qualified medical professional.
This information has been left in for historical purposes but should not be acted upon.
a term applied to the hydrate of potassium, KHO, either in the liquid or solid state, but sometimes used to denote potassium oxide and also crude carbonate of potassium. Potash salts are essential constituents in the human body, but if, when wasted, they are supplied directly to the blood they are very poisonous. A much diluted solution of potash is antacid and sedative in dyspepsia and cutaneous diseases, also in pleuritis, pericarditis, scrofula, etc. Caustic potash is used externally as a caustic in ulcers, etc.; carbonate of potash has been given in whooping cough; acetate of potash, nitrate of potash, and, in small doses, tartrate of potash are diuretics; acid tartrate of potash is purgative and used in dropsy; citrate of potash is diuretic and febrifugal; sulphate of potash is a mild purpat gative generally given with rhubarb, etc.; nitrate of potash and chlorate of potash are refrigerants and diuretics.
The Encyclopedia of Founding (1892)
This substance exists in plants, combined with other organic acids. The plants being burned destroys the combination, the organic acids being decomposed into carbonic acid and water, and the liberated potash unites with some of the carbonic acid formed by the combustion, thus producing carbonate of potash. This salt is highly alkaline, is used to prepare caustic potash, and for the manufacture of soap, glass, etc. Wood-ashes furnish from 20 to 50 per cent of their weight of carbonate of potash, being obtained from them by leaching and boiling the solution to dryness in iron pots. See ALKALI; ASHES.
Aiton's Encyclopedia (1910)
. See Potassium
What Has Changed in the Last Century
When the Encyclopedia of Founding described potash in 1892 as leached from wood ashes and boiled down in iron pots, that was still a real industry; today essentially all the world's potash is mined or brine-extracted from buried evaporite beds, and the word usually means potassium chloride sold as fertilizer rather than the carbonate or the caustic hydrate. Germany dominated the trade from its Stassfurt deposits until the First World War; the huge Saskatchewan beds, found by drillers looking for oil in the 1940s, made Canada the largest producer, with Russia and Belarus close behind, and sanctions on Belarus after 2020 sent prices sharply upward. The medical list in Collier's of 1921 is entirely obsolete: diluted potash is not a treatment for scrofula, pleurisy or whooping cough, and caustic potash is never applied to ulcers. What survives unchanged is the chemistry, since potassium remains one of the three nutrients plants must have in quantity, which is why potash is still traded by the millions of tonnes.
Written for this edition, 2026.