The probability is, that the animal charcoal, when instantaneously applied, may be sufficiently porous and absorbent to extract the venom from the recent wound, together with a portion of the blood, before it has had time to be carried into the system; and that the blood which Mr. Faraday detected in the specimen submitted to him was that of the Indian on whose person the effect was exhibited on the occasion to which my informant was an eye-witness.  The snake-charmers from the coast who visit Ceylon profess to prepare the snake-stones for themselves, and to preserve the composition a secret.  Dr. Davy[1], on the authority of Sir Alexander Johnston, says the manufacture of them is a lucrative trade, carried on by the monks of Manilla, who supply the merchants of India—­and his analysis confirms that of Mr. Faraday.  Of the three different kinds which he examined—­one being of partially burnt bone, and another of chalk, the third, consisting chiefly of vegetable matter, resembled bezoar,—­all of them (except the first, which possessed a slight absorbent power) were quite inert, and incapable of having any effect except on the imagination of the patient.  Thunberg was shown the snake-stone used by the boers at the Cape in 1772, which was imported for them “from the Indies, especially from Malabar,” at so high a price that few of the farmers could afford to possess themselves of it; he describes it as convex on one side, black and so porous that “when thrown into water, it caused bubbles to rise;” and hence, by its absorbent qualities, it served, if speedily applied, to extract the poison from the wound.[2]

[Footnote 1:  Account of the Interior of Ceylon, ch. iii. p. 101.]

[Footnote 2:  Thunberg, vol. i. p. 155.  Since the foregoing account was published, I have received a note from Mr. HARDY, relative to the piedra ponsona, the snake-stone of Mexico, in which he gives the following account of the method of preparing and applying it:  “Take a piece of hart’s horn of any convenient size and shape; cover it well round with grass or hay, enclose both in a thin piece of sheet copper well wrapped round them, and place the parcel in a charcoal fire till the bone is sufficiently charred.

“When cold, remove the calcined horn from its envelope, when it will be ready for immediate use.  In this state it will resemble a solid black fibrous substance, of the same shape and size as before it was subjected to this treatment.

“USE.—­The wound being slightly punctured, apply the bone to the opening, to which it will adhere firmly for the space of two minutes; and when it falls, it should be received into a basin of water.  It should then be dried in a cloth, and again applied to the wound.  But it will not adhere longer than about one minute.  In like manner it may be applied a third time; but now it will fall almost immediately, and nothing will cause it to adhere any more.

“These effects I witnessed in the case of a bite of a rattle-snake at Oposura, a town in the province of Sonora, in Mexico, from whence I obtained my recipe; and I have given other particulars respecting it in my Travels in the Interior of Mexico, published in 1830.  R.W.H.  HARDY. Bath, 30_th January_, 1860.”]