Acid test (gold) 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 dissolves 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 differing strengths of aqua regia and comparative testing of gold items of known fineness. The figurative meaning of the expression, where it is applied to tests of character,
Metal Gear Acid Metal Gear Acid , stylized as METAL GEAR AC!D, is a turn-based collectible card tactical RPG video game developed by Konami Computer Entertainment Japan for the PSP handheld game console. The game was first unveiled at E3 in May 2004, and was released in Japan on December 16, 2004, in North America on March 22, 2005, and in Europe on September 1, 2005. It was the first game in the "Metal Gear" series for the PSP. A Java ME version for mobile phones was released by Glu Mobile in titled "Metal Gear Acid Mobile". "Acid" focuses on turn-based tactics, using