end of two or three months, the epidermis thus left in water, softens, does not swell, and is torn with great ease; it is not reduced to a pulp analogous to that of the other organs thus macerated. 3d. When stewed, the epidermis does not undergo, at the instant of ebullition, a horny hardening like all the other organs. Hence why, whilst by this horny hardening the skin is much diminished in extent, the epidermis which remains the same is obliged to be folded in different directions. When the ebullition is continued, this membrane becomes less resisting and breaks with great ease, but is never reduced to gelatine, does not acquire a yellowish colour, and does not become elastic like the organs which furnish much of this substance; besides, we know that the epidermoid texture does not combine with tannin, and that it is even an obstacle to it when it tends to penetrate the skin. After long stewing, the different layers which compose the epidermis of the palm of the hand, and especially that of the sole of the foot, are separated with great ease; this is the best way of seeing this lamellated structure. Between these layers there is often formed on the foot small vesicles filled with serum. Caloric produces upon the epidermis phenomena wholly different from those which the other systems experience from the contact of this substance. A portion of this membrane well dried by the action of the air, and exposed to the flame of a candle, 1st, does not undergo hardly at all the horny hardening, as a portion of skin does when thus treated; 2d, it exhales a fetid odour analogous to that of burnt horn, and different from that of all the other textures when subjected to the same experiment; 3d, it burns with great ease, which does not take place with any of the preceding systems when dried; it is often even sufficient to put the fire to it at one end to consume it entirely; 4th, at the place of the flame we see a blackish bubbling fluid, from which often escapes little burning drops, and which is very analogous to that of a feather when burnt. It is evidently an oil which supports the combustion by its great abundance, and which does not appear to be found in as great quantity as in the hair and the nails. This oil deserves particular examination; it is that which gives out in burning so disagreeable an odour, and which forms those burning and whitish drops of which we have spoken. It appears to be of the same nature as that which Bertholet obtained from the hair in so great a proportion. After combustion there is left a blackish charcoal, which I have not analyzed. Light does not appear to have a great action upon the epidermis, which I have found of the same colour, in portions of skin blackened by it, and in those which have been sheltered from it.