The subject of melting the metal which is to be poured into molds is one of the most important considerations in the foundry. It is also one which has received much attention in the last few years, the endeavor being to get away from the old rule-of-thumb methods and to arrive in the iron foundry at something near the precision in resulting metal that is already attained in the brass shops or the steel foundry.
The heat for all melting is obtained from practically the same two chemical elements - carbon, and oxygen - carbon coming from the fuel, be it coal, coke, oil, or gas; and oxygen coming from the air of the blast.
The design of the furnace, the kind of fuel used, and the application of the blast vary in accordance with the peculiar properties of the different metals and the degree of heat required to melt them.
The melting of steel, copper alloys, and malleable cast iron will be dealt with under separate headings. We shall now consider only the melting of gray foundry irons.