Gold element silver (as electrum) and also naturally alloyed with copper and palladium. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides). Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term "acid test". Gold also dissolves in alkaline solutions of cyanide,
Acid perfusion test hoarseness, chronic cough, then 24 hr pH monitoring should be considered. Acid perfusion test Acid perfusion test, also called the Bernstein test, is a test done to reproduce the pain when the lower esophagus is irrigated with an acid solution in people with GERD (gastroesophageal reflux disease). There will be a negative result in normal people, but a false positive reading may be seen in up to 15% of people. Bernstein test is obsolete nowadays. 24 hour pH monitoring is the gold standard for GERD. However, the initial management is with proton pump inhibitors. If the patient does not respond