Rochelle salt

Rochelle salt

noun Chemistry, Pharmacology.
a colorless or white, water-soluble solid, KNaC 4 H 4 O 6 ⋅4H 2 O, used in silvering mirrors, in the manufacture of Seidlitz powders and baking powder, and in medicine as a laxative.
Also called potassium sodium tartrate.


Origin:
1745–55; after La Rochelle

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World English Dictionary
Rochelle salt
 
n
a white crystalline double salt, sodium potassium tartrate, used in Seidlitz powder. Formula: KNaC4H4O6.4H2O
 
[C18: named after La Rochelle, French port]

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Medical Dictionary

Rochelle salt Ro·chelle salt (rə-shěl', rō-)
n.
See potassium sodium tartrate.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Encyclopedia Britannica
Encyclopedia

rochelle salt

a crystalline solid having a large piezoelectric effect (electric charge induced on its surfaces by mechanical deformation due to pressure, twisting, or bending), making it useful in sensitive acoustical and vibrational devices. Like other piezoelectric materials, Rochelle salt crystals (KNaC4H4O64H2O) become strained when subjected to electric fields. They decompose at moderately high temperatures (55 C [131 F]) and require protection against moisture. Piezoelectric deformation is directly proportional to the applied electric field and reverses as the polarity of the applied field is reversed. These basic properties are put to use in electromechanical transducers such as ultrasonic generators, microphones, and phonograph pickups and in electromechanical resonators. See also tartaric acid.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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