whole extent of his arm and leg. With another red-hot iron he struck his heel and the point of the foot repeatedly : in this experiment the contact of the fire was longer than in any of the preceding. From the sole of his foot so much vapour was disengaged, that being very near the experimenter, my eyes and nose were sensibly affected. He also put between his teeth a heated iron, which, although not red-hot, was still capable of burning. It was announced that he had drunk half a glass of boiling oil; but, in fact, I found that he had never drunk such a dose, and that he had performed this twice by introducing a little into his mouth, not more than the third part of a spoonful, at a time. It was likewise said that he had washed his hands and face in boiling lead; but he now practised such an experiment only in rapidly bathing the extremities of his fingers in liquid lead, and also carrying a very small portion of it on his tongue. He afterwards passed a piece of red-hot iron. over his tongue, without showing the least painful sensation. His tongue, which I was able distinctly to observe in this often-repeated experiment, was covered with a crust similar to what is seen on the tongues of persons in fevers; that is to say, it was covered with a kind of paste of a dirty gray colour. He exposed his foot again to the flame of burning oil, but kept it at a certain distance. In short, he threw sulphuric, nitric and muriatic acids on inflamed charcoal, and immediately exposed his face over the vapours which arose from those acids, keeping a small part of it in that situation. The experiment with which Señor Lionetto is accustomed to terminate his exhibition, is that of passing through the skin of his arm a thick gold pin, which he does without feeling the least pain. In this proof of his insensibility, I observed that the pin entered his skin with difficulty, requiring such a force as if it had to perforate dressed leather. Now although at first view this fact seemed to have no relation with the others practised by means of fire, yet it appeared to me to throw some light on the examination of the phænomena relating to the pretended incombustibility. From these experiments, which I have seen so often repeated, I fanVol. 32. No. 125. Oct. 1808. D cied cied that Señor Lionetto's skin had become so insensible, from the effect of repeated frictions with some substances fit to produce such a change, by stimulating excessively the nerves and the vessels of the skin, and by recent usage, that it was capable of impeding in a certain degree the free passage of caloric. Besides the action of such substances, I thought that the force of habit must always have added to such a disposition, and that even the frequent impression of the fire should have contributed not a little to produce such insensibility in his skin: the experiment of the pin which he put through it, was to me no light argument of its hebetude. These opinions, however, were merely the effect of a system dictated by reason, and a knowledge of the laws of animal life: but had I not known the means used to render the skin incombustible, nor had any other knowledge of the subject, I should not have been able to give a plausible explanation of the more surprising phænomena; such as the red-hot iron which he so often passed over his tongue without suffering any painful impression; and much less with such a system could I account for the boiling oil which he swallowed neither could I imagine how he had prepared the internal surface of the oesophagus or of the stomach; and in what manner he could suffer the action of almost red-hot iron, which he put between his teeth, on the enamel of which it is not possible to preserve any mixture. Instead therefore of uselessly wasting time in simple conjectures, I resolved to adopt the best experimental art which I knew, trying on myself the action of all the means proper to benumb the cutaneous nerves, and to clothe the skin with a substance which was a nonconductor of caloric. Few substances belonging to chemical compositions, or to other natural bodies, appeared to me proper for the purpose which I had in view. The sharp sensation which was excited by the vapour disengaged by the contact of the fire with the incombustible membrane, and the chemical reason, induced me first to have recourse to acid substances, and to some of the acidulous salts. It would be too tedious to relate in detail all the various substances and experiments : which I made with some of them I attempted to rub my skin, which, after the liquids dried, was always sensible in the same degree to the action of the fire. The unfortunate result of my first experiments did not discourage me; persuaded that by the effect of only one rubbing, it was not possible to change the skin in such a manner as to render it insensible to the action of fire. I therefore repeated oftener on the same part the frictions with the same substance, and perceived the effect, that it gradually became less and less sensible to the action of caloric. On one part of my body I repeated the frictions so often with dilute (allungato) sulphurous acid, that I was finally able to pass a plate of red-hot iron over it without any injury. I afterwards discovered that dilute sulphuric, nitric, and muriatic acids would equally produce the same effect: but the sulphurous acid is preferable to all the others, as it produces the speediest and most certain effect. next tried the action of acidulous sulphat of alumine and potash, or the alum of commerce, a substance distinguished for its property of preserving bodies from the action of fire. In making a saturated solution of this salt, I discovered how much greater styptic powers it had acquired by being strongly agitated or boiled (bollirte sulla spugna *). With the fluid thus prepared, I rubbed one part of my arm several times, and did not before obtain such decided results; so that I have ever since used this solution. These essays, however, were only the rudiments of a knowledge of the phænomenon, the examination of which was still incomplete. An accidental combination afterwards induced me to undertake a new series of experiments, by which I might be enabled to give a more clear explanation of all the more difficult operations executed by Lionetto. Wishing to examine if washing the almost incombustible part would make it lose the quality it had acquired, I rub bed it with hard soap, washed and dried it with a cloth, and applied the same plate of red-hot iron. I then discovered, to my surprise, that the skin of that part not only Does the author mean burnt alum, i. e. alum boiled per se on an ironshovel without water? preserved the same insensibility to the action of red-hot iron, but had even become stronger than at first. I again rubbed the same part with soap without wiping it with the cloth, and passed over it the iron very red-hot, without feeling any painful sensation, or even having the hair burned. Remembering the crust which I observed on Lionetto's tongue, I determined to rub mine with the same soap; in consequence of which it became equally insensible to the action of fire. I began with pieces of iron slightly heated, raising them gradually till they were perfectly red-hot. I made a soft paste of soap triturated in a mortar, and water saturated with acidulous sulphat of alumine and potash (alum), agitated or boiled as above; and spreading this composition on my tongue, the experiment succeeded completely. Still more simple I found the process of first bathing the tongue with sulphurous acid, and afterwards rubbing it often with a piece of soap. The experiment succeeded still better if after bathing the tongue with this acid, I covered it with a thin stratum of sugar reduced to impalpable powder, and rubbed it afterwards with the soap in the same manner. The sugar in this case, like a mordant, made a greater quantity of soap attach to the tongue, and adhere more solidly. By this mode of operating, the solution of alum, or of dilute sulphurous acid, may be adopted at pleasure to benumb the nerves of the tongue, and the soap is a most efficacious means of obstructing (rifrangere) the action of caloric, the propagation of which it almost perfectly impedes. Of all the known substances, indeed, soap is that which of all others best merits the name of restrainer of caloric, as I shall show on another occasion. From these experiments I proceeded to that with the boiling oil, putting at first a very small drop considerably heated on the tongue, and afterwards increasing the dose and the temperature. The effect corresponded precisely to my expectation the oil put on the tongue thus prepared made a hissing noise, similar to that made by red-hot iron when brought in contact with a humid body; after the hissing the oil ceased to be hot, and was easily swallowed, perhaps in a state scarcely tepid. Thús furnished with facts, I now be lieved myself in a state to give the following explanation of the phænomena which I had seen executed by Señor Lionetto. I. The hair over which he passed the plate of red-hot iron had been first bathed in a solution of alum or in sulphurous acid, substances with which it was still wet even at the moment when touched with the iron. Hence the origin of the vapour which arises from his hair in this experiment. II. The plate of red-hot iron with which he rubbed his leg and arm produced no alteration, because those parts were prepared with the substances of which I have spoken. III. The same reason will explain the phænomenon of the stroke which he gave the red-hot iron with his foot, although the contact of the iron in this experiment was longer : but it is not difficult to comprehend how the sole of the foot may be conveniently prepared for this purpose, by the above or similar substances, it being in its nature the most callous and least sensible part of the body. The contact however of his foot with the plate of red-hot iron was certainly not of very long duration; on the contrary, it clearly appeared in this experiment, more than in any other, that his incombustibility did not surpass a certain limit, beyond which he might be burned, and like others was highly combustible. IV. With regard to the boiling oil; this phænomenon, as being the most striking in appearance, merits a more minute examination. To understand well such a fact, it is necessary to know the following particulars. Señor Lionetto took the inflamed oil from the fire, and, to give the public a proof of its high temperature, immersed in it a certain portion of lead, which melted, thereby demonstrating to what degree it was heated. To me it appears that such an artifice should contribute to cool the oil: this is clearly manifested by the known laws of caloric, the greater part of which is employed in the fusion of the lead. I was better convinced of this truth in repeating the same experiment with a thermometer in my hand, which after the fusion of the lead fell most sensibly. Of all the oil thus reduced to this temperature, he took barely a quarter of a spoonful; and this quantity he dexterously made to fall on his tongue only, which was perhaps prepared in such a manner that it cooled in an |