They first gradually habituate the skin, the mouth, throat and stomach to great degrees of heat, then they rub the skin with hard soap.

The tongue is also covered with hard soap and over that a layer of powdered sugar.

By this means an investigating professor was enabled to reproduce the wonders which had puzzled many scientists.
The investigating professor in all probability, was Professor Sementini, who experimented with Lionetto.

I find an account of Sementini's discoveries in an old newspaper clipping, the name and date of which have unfortunately been lost: Sementini's efforts, after performing several experiments upon himself, were finally crowned with success.

He found that by friction with sulphuric acid deluted with water, the skin might be made insensible to the action of the heat of red-hot iron; a solution of alum, evaporated till it became spongy, appeared to be more effectual in these frictions.