I have an electric mantle that I want to bathe reaction vessels at temperatures up to $\mathrm{750^{\circ}C}$. Obviously that rules out oils. What substances are used as bath media at such temperatures?
I was thinking of using lead or Rose's alloy, but wondering if there are more standard high-temperature bath chemicals? I suppose an ideal one would be both inert to lab steel, glass, and a standard atmosphere, and liquid down to room temperature.