Chemistry
Testing for gold with acid focuses around the fact that gold is a noble metal which is resistant to change by corrosion, oxidation or acid. The acid test for gold is to rub the gold-colored item on black stone, which will leave an easily visible mark. The mark is tested by applying aqua fortis (nitric acid), which dissolves the mark of any item that is not gold. If the mark remains, it is tested by applying aqua regia (nitric acid and hydrochloric acid). If the mark is removed, then this test dissolved the gold, proving the item to be genuine gold. More accurate testing of the item for its fineness or purity can be done through the use of differencing strengths of aqua regia and comparative testing of gold items of known fineness.
Read more about this topic: Acid Test (gold)
Famous quotes containing the word chemistry:
“For me chemistry represented an indefinite cloud of future potentialities which enveloped my life to come in black volutes torn by fiery flashes, like those which had hidden Mount Sinai. Like Moses, from that cloud I expected my law, the principle of order in me, around me, and in the world.... I would watch the buds swell in spring, the mica glint in the granite, my own hands, and I would say to myself: “I will understand this, too, I will understand everything.””
—Primo Levi (1919–1987)
“...some sort of false logic has crept into our schools, for the people whom I have seen doing housework or cooking know nothing of botany or chemistry, and the people who know botany and chemistry do not cook or sweep. The conclusion seems to be, if one knows chemistry she must not cook or do housework.”
—Ellen Henrietta Swallow Richards (1842–1911)
“If thought makes free, so does the moral sentiment. The mixtures of spiritual chemistry refuse to be analyzed.”
—Ralph Waldo Emerson (1803–1882)