Verb alum Definition and Examples



Definition as verb:

(transitive) To steep in, or otherwise impregnate with, a solution of alum; to treat with alum.

More definition:

1.Also called potash alum, potassium alum. a crystalline solid, aluminum potassium sulfate, K 2 SO 4 ⋅Al 2 (SO 4) 3 ⋅24H 2 O, used in medicine as an astringent and styptic, in dyeing and tanning, and in many technical processes. of a class of double sulfates analogous to the potassium alum, as aluminum ammonium sulfate, having the general formula R 2 SO 4 ⋅X 2 (SO 4) 3 ⋅24H 2 O, where R is a univalent alkali metal or ammonium, and X one of a number of trivalent metals.

3.(not in technical use) aluminum sulfate. alumna or alumnus.


1. Also called potash alum. a colourless soluble hydrated double sulphate of aluminium and potassium used in the manufacture of mordants and pigments, in dressing leather and sizing paper, and in medicine as a styptic and astringent. Formula, K2SO



2. any of a group of isomorphic double sulphates of a monovalent metal or group and a trivalent metal. Formula, X2SO


3.24H2O, where X is monovalent and Y is trivalent Word OriginC14, from Old French, from Latin alūmenCollins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollinsPublishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Cite This Source
late 14c., "whitish mineral salt used as an astringent, dye, etc.," from Old French alum, from Latin alumen "alum," literally "bitter salt," cognate with Greek aludoimos "bitter" and perhaps with English ale.

1. alumna

2. alumnae

3. alumni

4. alumnus alum. aluminum The American Heritage® Abbreviations Dictionary, Third EditionCopyright © 2005 by Houghton Mifflin Company.Published by Houghton Mifflin Company. All rights reserved. Cite This Source


Large deposits of alum occur close to the village of Bulladelah, 30 m.

The modern town in the immediate neighbourhood, still known as Fokia, was founded by the Genoese in 1421 on account of the rich alum mines in the neighbourhood.

P. Granville put into practice between Alum Bay in the Isle of Wight and the Needles lighthouse a method which depends upon conduction through sea water.

Later the Bournemouth station was removed to Poole Harbour, and the Alum Bay station to Niton in the Isle of Wight, the distance being thus increased to 30 m.

Other minerals found here are graphite, alum, potter's clay and roofing-slate, and, besides, famous silvermines were worked at Iglau during the middle ages.

Salts of ammonium were also known; while alum was used as a mordant in dyeing.

Among the Arabian and later alchemists we find attempts made to collate compounds by specific properties, and it is to these writers that we are mainly indebted for such terms as "alkali," " sal," &c. The mineral acids, hydrochloric, nitric and sulphuric acids, and also aqua regia (a mixture of hydrochloric and nitric acids) were discovered, and the vitriols, alum, saltpetre, sal-ammoniac, ammonium carbonate, silver nitrate (lunar caustic) became better known.

For example, episomorphs of white potash alum and violet chrome alum, of white magnesium sulphate and green nickel sulphate, and of many other pairs of salts, have been obtained.

K A1um=z00% K Alum= o/, Tl Alum= o% Tl Alum_ zoo FIG.

The cups when full are poured into a larger vessel, and solution of alum is added to coagulate the latex.

ALUM, in chemistry, a term given to the crystallized double sulphates of the typical formula M 2 SO 4 � MP' �(S04) 324H20, where M.

The presence of sulphuric acid in potash alum was known to the alchemists.

He also showed that crystals of alum cannot be obtained by dissolving alumina in sulphuric acid and evaporating the solutions, but when a solution of potash or ammonia is dropped into this liquid, it immediately deposits perfect crystals of alum (Sur la regeneration de l'alun, Marggraf's Opusc. ii.

Chaptal published the analysis of four different kinds of alum, namely, Roman alum, Levant alum, British alum and alum manufactured by himself.

This property seems to characterize a solution of iron sulphate in water; a solution of ordinary (potash) alum would possess no such property.

From the name schistos, and the mode of formation, there can be little doubt that this species was the salt which forms spontaneously on certain slaty minerals, as alum slate and bituminous shale, and which consists chiefly of the sulphates of iron and aluminium.

As alum and green vitriol were applied to a variety of substances in common, and as both are distinguished by a sweetish and astringent taste, writers, even after the discovery of alum, do not seem to have discriminated the two salts accurately from each other.

Various minerals are employed in the manufacture of alum, the most important being alunite or alum-stone, alum schist, bauxite and cryolite.

This powder is then lixiviated with hot water, the liquor decanted, and the alum allowed to crystallize.

It is now allowed to stand for some time, decanted from any sediment, and finally mixed with the calculated quantity of potassium sulphate (or if ammonium alum is required, with ammonium sulphate), well agitated, and the alum is thrown down as a finely-divided precipitate of alum meal.

When cryolite is used for the preparation of alum, it is mixed with calcium carbonate and heated.

"Neutral alum" is obtained by the addition of as much sodium carbonate to a solution of alum as will begin to cause the separation of alumina; it is much used in mordanting.

Sodium alum, Na 2 SO 4 �Al 2 (S04) 3 �24H 2 O, occurs in nature as the mineral mendozite.

Chrome alum, K 2 SO 4 �Cr 2 (SO 4) 3.24H 2 O, appears chiefly as a by-product in the manufacture of alizarin, and as a product of the reaction in bichromate batteries.

Its chief mineral products are coal, nitre, sulphur, alum, soda, saltpetre, gypsum, porcelain-earth, pipe-clay, asphalt, petroleum, marble and ores of gold, silver, mercury, copper, iron, lead, zinc, antimony, cobalt and arsenic. The principal mining regions are Zsepes-Giimor in Upper Hungary, the Kremnitz-Schemnitz district, the Nagybanya district, the Transylvanian deposits and the Banat.

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