—When two or more metals are melted together and mixed they form what is called an alloy.
Brass.
—This well known alloy is made by mixing zinc with copper. There are twenty or more different kinds of brass but common brass is made of 36 parts of zinc and 64 parts of copper.
Brass is harder than copper and while it can be hammered and drawn it is not nearly as malleable or as ductile as copper. It can be sawed, drilled, threaded and machined easily and is about the best alloy you can use for making small parts of machines.
Type-metal.
—All kinds of metals shrink when they cool after being run into a mold and so the edges of the castings are never very sharp.
Now type metal which is an alloy made of 80 parts of lead and 20 parts of antimony will expand and this is the reason why type is so beautifully clear and sharp. So if you want to cast little parts of machines and engines and the like you can do a good job by using type-metal. As it melts at a low temperature you can melt it in an iron ladle over the kitchen fire.
Pewter.
—This alloy, which is made of 75 parts of tin and 25 parts of lead, in Colonial days was much used for making all kinds of table-ware and household utensils and it will come into vogue again I hope. More will be said about [this alloy] and how to work it in the next chapter.