Mercury is much used for making thermometers and barometers. It is also used for extracting gold and silver from their ores, by allowing the crushed ore to flow in a thin mud over plates covered with mercury. The gold amalgamates with the mercury, and is separated later by distillation:
Mercury was once much used for silvering the backs of mirrors but a solution of silver has been found to be cheaper for this purpose. Mercury unites with most of the other metals to form alloys, called amalgams. Amalgams of silver and other metals are used in filling teeth.
Mercury is the basis of fulminating mercury, the explosive powder put into percussion caps, cartridges, and fuses. Dry fulminating mercury will explode violently when struck with a hammer or any other hard object. When wet it is non-explosive and is kept in this condition until wanted for use. It can be obtained as a fine, gray powder by shaking it violently with flour, grease, etc., so as to coat the minute drops and prevent them from uniting to form a fluid mass. Pure dilute acids do not attack mercury, but concentrated nitric acid dissolves it readily.