“regal water” or “Royal water”) is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange (sometimes red) fuming liquid, so named by alchemists because it can dissolve the noble metals gold and platinum, though not all metals.

Sand heated up faster than water because sand has a color and water is clear. Sand heated up faster than water because sand is darker than water; dark colored materials will absorb more light.

The University of Nottingham published a video showing gold dissolve into aqua regia (a mixture of nitric acid and hydrochloric acid). But if you can put gold into solution that contains both acids, then it can react, and in fact, can indeed dissolve gold – which is why Aqua Regia is also known as ‘royal water.”

Metallic gold does not dissolve in strong sulphuric acid unless a little nitric acid is added when a yellow liquid is formed, which, when diluted with water, deposits the metal as a violet or brown powder. A boiling concentrated solution of ferric chloride readily dissolves gold.

Sulfuric acid can dissolve gold, but it is a very dangerous process as the sulfuric acid has to be concentrated and heated to the point sulfur dioxide gas is fumed off, silver or gold will dissolve gold will form a gold persulfate soluble in the very concentrated acid, upon dilution the gold will precipitate out of …

Even dilute sulfuric acid reacts with many metals via a single displacement reaction as with other typical acids, producing hydrogen gas and salts (the metal sulfate). It attacks reactive metals (metals at positions above copper in the reactivity series) such as iron, aluminium, zinc, manganese, magnesium, and nickel.

Drop a very small amount of hydrochloric or sulfuric acid onto the gold. If the gold begins to dissolve, then there is some other type of metal mixed with the gold and it is not pure. Check to see if there are any markings on the piece. Different types of acid are used to test particular karats.

Another source of acid can be found in your local auto parts store under the name “battery acid.” Battery acid is a dilute form of sulfuric acid, but any of them will work for this test. If the material forms than crystals, and it is the color of gold is most probably fools gold.

Gold is not soluble in sulphuric acid except when nitric acid or some other oxidising agent is present. In this case it is again precipitated on dilution with water. The sulphate of iron formed is insoluble in strong sulphuric acid. Tin and antimony are also dissolved, but form basic salts on dilution.