The surface of the gold is just "wet" by mercury, and the gold is not decolored. A minute quantity of mercury may swarm over a gold surface, giving the impression that the color has changed fairly rapidly, yet the illusion is just temporary. As soon as the mercury dries, the color returns to its original state.
When you pour mercury into a glass, it forms a layer on the bottom of the container. This layer prevents any more mercury from spilling out. The mercury in this layer is not liquid; rather, it is a solid at room temperature.
You can think of mercury as a kind of paint with a low melting point. When you paint a wall, the paint melts initially to create a smooth surface, then hardens back up once it's had time to dry. With mercury, this process happens much faster than with ordinary paint. There is no need for high temperatures or long exposure times to get a shiny result.
The color of gold does not come from any ingredient in the metal itself, but from elements found in combinations within the gold object. These elements are gold, copper, and other metals. As an object made of gold is exposed to air, the colors found in the stone used to fabricate it will usually show through.
Gold may be dissolved in a solution of chlorine and nitric acid. In order for mercury to cling to gold, it must be clean. Sometimes placer gold is coated with a thin layer of oil, which prevents the gold from amalgamating unless the oil is removed first. The easiest way to do this is to heat the material together in an oven.
The gold can then be separated from the mercury by simple gravity. The mixture is placed into a container with a narrow bottom, such as a glass or plastic tube. The weight of the gold above the level of the mercury will dissolve it away. The solution is then heated until only gold remains. It can be tested for purity using a chemical test kit.
If you are working with other metals that might be used to coat gold (such as silver or copper), you should follow the instructions below.
Copper and silver are both useful materials for coating gold because they will bond to each other. This means that once the metal has been cleaned it cannot be used again. There are two ways of removing these coating layers: fusion cutting or chemical dissolution.
Fusion cutting works by heating the object up to around 600 degrees Celsius (1100 degrees Fahrenheit) and plunging it into a pool of water. The heat causes the metal to melt, allowing you to cut it free.
Because gold is a result of how light is reflected by an item, it does not exist independently of the object. It is not a color in the same way that blue or red are. Gold is called a color because we can say that things with much gold will be white or yellow, but not actually see one without knowing what they are first. The same is true of silver and platinum.
Gold has two primary colors of light: yellow and white. These are the only colors of light you can produce when you shine light on gold. The other colors of light are mixtures of these two; for example, green is said to be a mixture of yellow and blue. When you look at the rainbow, you are seeing different mixtures of these three colors of light: red, orange, yellow, green, blue, indigo, and violet.
Silver has two primary colors of light too: yellow and white. But unlike gold, which always reflects both colors, silver usually reflects only one of them. So if you look at something made of silver, you can see how light of the two colors affects its appearance. Platinum has four primary colors of light: yellow, white, red, and black.
Bare platinum objects look black because all the light is absorbed.
When gold jewelry changes color, it indicates that it either contains less gold than the metals used in its creation or that it is not real gold jewelry and just has a gold plating finish. Gold-plated jewelry and jewelry containing lesser carat gold tarnish with time due to metal abrasion. The colors of the metals themselves are not affected by oxidation.
The most common sources of colored gold are brass (which can contain up to 20 percent copper) and silver (which can contain up to 30 percent zinc). The metals within these alloys oxidize differently than pure gold and so will cause it to tarnish at different rates. For example, brass tends to tarnish more quickly than silver because more copper increases the rate at which it oxidizes.
People often ask me about gold dust. It is not actually gold dust, but rather any gold-colored material that is composed primarily of particles of gold. Gold dust is made when you burn solid gold objects (such as coins or jewelry) with the ash left over after burning other materials such as wood or coal. The word "dust" comes from the appearance of the material when first dug out of the fire. It looks like dry sand.
Gold dust is useful for adding color to other materials. For example, if you wanted to paint a wall blue, you could mix gold dust with acrylic paint and then brush the mixture onto the wall.