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Crystal of potassium alum, KAl(SO 4) 2 ·12H 2 O. An alum (/ ˈ æ l ə m /) is a type of chemical compound, usually a hydrated double sulfate salt of aluminium with the general formula X Al(SO 4) 2 ·12 H 2 O, such that X is a monovalent cation such as potassium or ammonium. [1] By itself, "alum" often refers to potassium alum, with the ...
Take five parts of pure flowers of nitre, three parts of Cyprus vitriol and two parts of Yemen alum. Powder them well, separately, until they are like dust and then place them in a flask. Plug the latter with a palm fibre and attach a glass receiver to it.
Ammonium aluminium sulfate, also known as ammonium alum or just alum (though there are many different substances also called "alum"), is a white crystalline double sulfate usually encountered as the dodecahydrate, formula (NH 4)Al(SO 4) 2 ·12H 2 O. It is used in small amounts in a variety of niche applications.
Natural alum (aluminum sulfate) has been the most common metallic salt mordant for millennia (see Papyrus Graecus Holmiensis, mordant and dye recipes start at recipe #84), but tin (stannous chloride), copper (cupric sulfate), iron (ferrous sulfate, called copperas) and chrome (potassium dichromate) are also used. Iron mordants "sadden" colors ...
Aluminium granules have been found safer and economical compared to atomized aluminium powder. Aluminium granules have lower explosion risk in production and in use ...
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Aluminium sulfate is sometimes called alum or papermaker's alum in certain industries. However, the name " alum " is more commonly and properly used for any double sulfate salt with the generic formula X Al(SO 4 ) 2 ·12H 2 O , where X is a monovalent cation such as potassium or ammonium .
Tops and flowers of heather, Calluna, fraoch; Weld, Reseda luteola, "lus-buidhe mòr", dried, reduced to powder and boiled. Leaves and twigs of dwarf birch, beithe-bheag; Bright yellow Sundew – Drosera rotundifolia, "lus na feàrnaich" with ammonia; Rich Yellow St John's Wort, achlasan Chalum cille, fixed with alum; Dirty yellow Peat soot ...