It only depends on using a coherent definition of "double". It doesn't make sense to multiply and divide temperatures measured in °F or °C; those are interval scales, not ratio scales. In the US men's shoe size 3 is 9.25 inches long, and shoe size 12 is 12.25 inches long. Would you say that size-12 feet are four times as long as size-3 feet? Multiplying and dividing temperatures measured in °F or °C is the same error. (Multiplying and dividing ΔT measured in °F is fine, though.)

It's easy enough to melt 1000-series aluminum foil with a wood fire, and people commonly melt parts of beer cans in wood fires as well (ten times thicker but with a lower melting point). Aluminum ingots usually require at least a charcoal fire, and usually forced-air convection as well. But, as someone commented in another thread, babbitt is a much more likely candidate for the metal in question, because why would a logger be carrying around aluminum ingots in their truck? Especially in the 01930s. Ingots are for remelting, and that's a sensible thing to do in the field with babbitt in a non-emergency situation, much less so with aluminum.