THE UNCOMMON ORIGINS OF SOME COMMON EXPRESSIONS - Acid Test

In this series I will write the origins of some of the most common expressions of phrases that we use in ours day to day life. The facts given here are extracts from a book by the same name that I got long time back from Reader's Digest. I wholeheartedly thank the author 'John Kahn' for this amazing book of trivia

ACID TEST

Any crucial or decisive test - whether of a soldier's courage or a motor car's suspension - is today referred to as an acid test.This phrase dates back to the early years of the 20th century. But what was the original acid test?

It was not, as might be supposed, a test of an acid's strength, or a test for the presence of an acid. It was a test by an acid - the test for trhe presence or amount of gold in a given metal object such as a ring or a spoon. The acid in question was nitric acid, which dissolves the base metals in an alloy but cannot dissolve gold. The test is still used by jewelers when making valuations or checking for forgeries.