alum

aluna

alumni An astringent salt, usually occurring in the form of pale crystals, much used in the dyeing and tanning trade and in certain medicines, and now understood to be a double sulphate of potassium and aluminium (K2SO4.Al2(SO4)3.24H2O). (defdate)
1991, Felix Gilbert, The Pope, His Banker, and Venice, http://books.google.com.au/books?id=MORXQFrm1jsC&pg=PA80&dq=%22Alum%22%7C%22Alums%22&hl=en&sa=X&ei=vL5PU_auOoLOkwWF7YCQBg&redir_esc=yv=onepage&q=%22Alum%22%7C%22Alums%22&f=false page 80,

Venice also needed alum for trade, since it was the point of departure for overland transportation of alum to southern Germany and its cloth-manufacturing Free Cities.

A natural astringent and antiseptic, potassium alum was coveted for its medicinal and cosmetic properties.

With weld and cochineal, which are colouring matters the most sensible to the action of sulphate of iron, the purified alums gave us colours more brilliant, fresh, and in a slight degree lighter; while those with our common alums were all duller, and evidently of a deeper hue.

For similar reasons, aluminium sulphate and alums are used in dyeing cloth.(..)Normally alums are soluble in water and insoluble in alcohols.

In structure, the alums consist of simple ions, being not complexes, but double salts. Potash alum or potassium alum is the common alum, with the formula KAl(SO4)2.12H2O) which, for convenience, may be written K2SO4.Al2(SO4)3.24H2O

(rfquotek)

Evanston-North Shore alums are happy to open their homes to Sigma actives for special social events.

You'll remember that we're starting with a list of slightly over 7,000 names that are alums (most of them over 50) that we'd like to whittle down to a manageable list of prospects.

All schools that last have alums, and, ancient as it was by American standards, Trinity by mid-century had thousands.