According to Wikipedia
Let's get our definitions straight----
"An alloy of various metals, primarily copper and lead. It is frequently employed in casting, due to its low melting point. There were many formulas; the term is generic.
Although cookpots in the nineteenth century were made of a cast iron that is not a modern structural material, the term does not refer to this cheap metal but to the fact that the metal could melt in a pot and be easily cast.
It was used for all sorts of fitments in cheap machinery, including cars. Radiator caps, door handles, carburetor bowls, and handles which incorporated fastening threads were made of this metal, for example. These would be stronger than still cheaper alternatives, but wouldn't be as strong as a part machined from steel or bronze, and are subject to breakage and pitting. Auto restorers can find them hard to replace. In the 1950s, the fancy moulded taillight housings, for example, were switched to be made of zinc and then chrome-plated."
(edited to add quotation marks)
I have found Wikipedia to be a pretty reliable source of information like this.
K