roche alum

American  

[rohch] / roʊtʃ /

noun

Chemistry.

1. an alumlike substance derived from alunite.

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Etymology

Origin of roche alum

1400–50; roche cliff, rocky height (now obsolete), late Middle English ( see rock ¹); apparently partial translation of Middle French alum en roque, alun de roche

Example Sentences

To dye white gloves of a beautiful purple, boil four ounces of logwood, and two ounces of roche alum, in three pints of soft water, till half wasted.

From The Cook and Housekeeper's Complete and Universal Dictionary; Including a System of Modern Cookery, in all Its Various Branches, Adapted to the Use of Private Families by Eaton, Mary, fl. 1823-1849

This article must first be prepared, by being steeped for several days in a mixture of roche alum, vitriol, verdigris, and copper filings, infused in white wine vinegar.

From The Cook and Housekeeper's Complete and Universal Dictionary; Including a System of Modern Cookery, in all Its Various Branches, Adapted to the Use of Private Families by Eaton, Mary, fl. 1823-1849

By infusing brazil wood, French berries, or indigo in the vinegar, with a little roche alum, either red, yellow, or blue may be produced.

From The Cook and Housekeeper's Complete and Universal Dictionary; Including a System of Modern Cookery, in all Its Various Branches, Adapted to the Use of Private Families by Eaton, Mary, fl. 1823-1849