A representative type of “madstone” is a concretionary calculus occasionally, but very rarely, found in the gullet of male deer. In form it bears a resemblance to a water-worn pebble and is usually of oblong shape, the largest specimens being 3 inches in length and 1½ inches in width. The chemical analysis of Dr. H. C. White showed that the chief component was tricalcic phosphate. His experiments demonstrated that while such a concretion would absorb water to the amount of 5 per cent. of its own weight, the quantity of blood or other fluid it was able to absorb only amounted to 2.3 per cent. of its weight. When immersed in water, after having been placed on a wound caused by the bite of a venomous creature, the liquid absorbed was given out so as to discolor the water, and the material exuded was found to be of toxic quality. However, experiments with animals that had been bitten by snakes or other reptiles, failed to show that the stone exercised any curative effect. Dr. White states that he has in his possession a “madstone” dating from 1654, but this is of a different type, being a porous sandstone.[477] Even in South Africa snake-stones are known, but it appears that the few specimens reported had been brought thither from the Dutch East Indies; one such stone had been handed down for generations in a Dutch settler’s family. From their appearance some of these snake-stones were judged to be pieces of burnt hartshorn. A Boer farmer owned an amulet of this kind that he would loan from time to time to neighbors who might have need of it. On one occasion, when the daughter of an English hunter had been bitten by a snake, the father sent off a man on horseback to borrow this snake-stone. Owing to the unavoidable delay, some hours elapsed before it could be applied to the wound. The girl recovered after its use but the wound did not heal satisfactorily, and this was attributed to the length of time that had intervened between the attack of the snake and the use of the remedial stone.[478] In December, 1887,[479] the writer described a white opaque variety of hydrophane with a white, chalky or glazed coating, which had recently been brought from a Colorado locality. The absorbent quality of this stone is quite remarkable, and when water is allowed to drop on it, it first becomes very white and chalky, and then gradually perfectly transparent. This property is developed so strikingly that the finder proposed the name “Magic Stone” for the mineral and suggested its use in rings, lockets, charms, etc., to conceal photographs, hair, and other objects, which the wearer wishes to reveal only as caprice dictates. VI Angels and Ministers of Grace