Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
In addition, this page gives alloy formulas with a high lead content and specifies them for beer-taps and other fittings that carry drink. Lead dissolves into beverages from such fittings and accumulates in the body; there is no safe level of exposure.
This information has been left in for historical purposes but should not be acted upon.
Pot-metal
An alloy of lead and copper, and called pot-metal when the alloy consists of these two metals only, exclusive of any other. The object in making pot-metal is to use as much lead as possible, and thus obtain a cheap compound for use on the commonest class of work, such as beer-taps, etc. A mixture of copper 16, lead 2 makes a ductile alloy of a red color. When the mixture consists of copper 16, lead 4, its redness and ductility are very perceptibly decreased. Copper 16 and lead 6 is the real pot-metal, and is commonly termed "dry pot-metal," or cock alloy. Beyond this proportion of lead there is danger of the lead separating from the alloy as it cools; but by careful manipulation it is possible to make a compound of copper 16 and lead 8, which is termed "wet pot-metal." The addition of a small proportion of tin to wet pot-metal will prevent the lead from separating, as tin may be mixed in almost any proportion with the alloy; and if the mixture consist of copper 16, lead 7, antimony 1, the same effect is obtained; but it is no longer the true pot-metal when these additions have been made. See COPPER; LEAD; ANTIMONY; TIN.