Acid test

Posted by ESC on September 16, 2001

In Reply to: Acid test posted by Craig S. on September 16, 2001

: The origin is close but not exact. A specific combination of acids call aqua regia is used to test for gold. It is the only combination which will react to gold. It is made up of hydrochloric and nitric acids.

How about this...
ACID TEST - "meaning a sternly critical examination, one designed to reveal even the slightest flaw, comes from the use of nitric acid to test gold. Inferior metals may be decomposed by the acid - but not gold." Morris Dictionary of Word and Phrase Origins by William and Mary Morris (HarperCollins, New York, 1977, 1988).