“…they use a minute amount of uranium or radium as catalyst to release the energy in the fuel. Uranium has low activity; it will set off only metals like the alkalis, and ships using uranium motors burn salt. And radium, being more active, will set off the metals from iron to copper; so ships using a radium initiator usually burn one of the commoner iron or copper ores."
Stanley Weinbaum - Redemption Cairn
OK, so assuming that Weinbaum's engines needs tons of fuel (I'm thinking say 100 tons of salt to get a freighter to Mars - PLEASE don't tell me how badly I've got it wrong), I need to know how much the chemicals would have cost in industrial quantities circa the 1930s.
Copper salts - is copper sulphate the most readily available for industrial purposes?
Iron salts - I would have said carbonates were the most common form, but I'm not sure. Iron sulphate?
I can make sodium chloride arbitrarily cheap because it's a by-product of one of the types of power plant I've mentioned - an atomic blast that uses some of the sodium chloride in sea water as fuel to make steam for a turbine generator, with lots of salt and purified water as byproducts. But it'd be good to have an idea of how much it cost in the real world at that time.
Anyone got any idea?
Later Found a web site with quite a lot of commodity prices, the National Bureau of Economic Research
Iron Ore - $4.50 / long ton
Copper - 9.00 cents per pound (don't have ore prices, presumably less) = $201.60 / long ton
Can't so far find a price for salt but I think I can safely set it fairly low.