Hobbies And Interests
Needed Chemicals
Buy small bottles of nitric acid, hydrochloric acid and potassium nitrate. You can sometimes buy nitric acid and potassium nitrate in a well-stocked drug store, but you might have to go to a chemical supply house in a larger city.
Sulfuric acid is used to make hydrochloric acid. Building supply stores sell hydrochloric acid under the generic name of muriatic acid. Brick masons use it to clean bricks and concrete surfaces.
You will make bottles with different combinations of these ingredients. Label your bottles and make sure you do not get the caps mixed up.
Testing Formulas
To test for the presence of gold, use a solution of 10 grams (about 1/3 ounce) potassium dichromate with 3/4 ounce nitric acid and 1/4 ounce of distilled water.
To test for gold that is 14 to 18 karat, mix one part hydrochloric acid to 12 parts of distilled water and 50 parts nitric acid.
To test for gold that is above18 karat, mix one part nitric acid to three parts hydrochloric acid. This solution is called aqua regia.
Testing Procedure
File a small notch in the piece you want to test.
Use an eyedropper to apply the chemical. Use rubber gloves and protective glasses or goggles to protect your eyes.
Apply a small drop of the solution to the scratch. If the piece is gold, there will be no reaction.
If the piece is made of copper, it will turn brown. If it is brass, it will turn dark brown. If it is lead or tin, it will turn yellow. If it is pure silver, it will turn bright red. Smaller percentages of silver will turn it green or brown.
Tip
You can tell if gold is mixed with other metals by holding a magnet near the piece. Gold does not respond to a magnet. If the piece is attracted to the magnet, then there are metals other than gold in the piece.