"No! Having the evidence of my senses, I cannot be deceived; if it had been a matter of opinion I might, but seeing, you know, is believing." Now the piece of lead, cast from a plaster mould of the performer's teeth, has probably officiated in a thousand previous performances, and is placed in the mouth between the gum and the cheek, just before the trick commences.

The spoon is made with a hollow handle containing quicksilver, which, by a simple motion, can be let run into the bowl, or back again into the handle at will.
The spoon is first shown with the quicksilver concealed in the handle, the bowl is then dipped just within the rim of the pot containing the molten lead, but not into the lead itself, and, at the same instant the quicksilver is allowed to run into the bowl.

The spoon is then shown with the quicksilver (which the audience takes to be the melted lead) in the bowl, and when placed in the mouth, the quicksilver is again allowed to run into the handle.
The performer, in fact, takes a spoonful of nothing, and soon after exhibits the lead bearing the impression of the teeth.
Molten lead, for fire-eating purposes, is made as follows: Bismuth.

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