Jo asks: What is "a malted"?

It is a milk shake (the standard US term, milk and ice cream whirred together with some flavoring) with the addition of a malt powder, the exact nature of which I do not know, but I doubt I would ever use it to make beer.

I also suddenly remembered the phosphate, a soda fountain drink available in, at least, Iowa during the 50s. Presumably it used phosphorus instead of sodium.

And, jo, thanks for the dangerous slang warning site.