How To Make Gold Test Solution
A solution of Stannous Chloride called “Purple of Cassius” has been used for centuries by gold prospectors to test for the presence of gold in a solution. It would give them a rough idea of how rich the gold is in the ore deposit. This is determined by the color of the reaction that could range from a light pink to a dark purple. The darker the purple, the richer the gold ore.
This Gold Test Solution is easy to make and you should not make a lot at one time as the ‘shelf life’ is not long.
You will need:
- Stannous Chloride.
- Concentrated Hydrochloric Acid.
- Distilled Water.
- Dropper Bottle.
- Glass Stir Rod.
First add a small amount of the stannous chloride to the bottle. Then add hydrochloric acid to fill half the bottle. Stir with the glass rod until all of the salt is dissolved. Now add distilled water to fill the rest of the bottle
Solutions containing gold will turn purple when tested with a few drops of this Gold Test Solution.
Side Note: Purple of Cassius is a purple pigment formed by the reaction of gold salts with tin(II) chloride. It has been used to impart glass with a red coloration (i.e. stained windows), as well as to determine the presence of gold in a sensitive chemical test.