Mercury glass was developed in Germany in the 1800s and rose in popularity to move across Europe and into the United States. It became popular as an inexpensive alternative to silver, as mercury glass is clear glass that has been hand-blown with a silvery substance inside. The silvery liquid used to color mercury glass is not actually mercury, though some manufacturers originally did attempt to use mercury to color it, which is where the name originated.
Spray glass cleaner on your paper towel or put enough warm water on the rag to make it damp. Ammonia can also be used on the rag, as it will not harm the outside of your mercury glass.
Gently wipe the piece of mercury glass with the damp rag.
Dry the piece of mercury glass with a dry rag or paper towel.
Because humidity and wetness can destroy the silvering on the inside of your piece of mercury glass, make sure the inside stays dry. If the seal or plug at the bottom of your piece breaks or comes out, reseal it or plug it. If you don't, the inside of the glass could become wet when you clean the outside.
Do not submerge your pieces of mercury glass in water or ammonia. It is imperative not to let any water or ammonia come into contact with the silvery finish inside the glass.
Do not use a rough cloth or scouring pad to clean your mercury glass; it could scratch the surface of the glass.