presented the king with a fire-stone which, he said, had been brought from India. De Thou narrates that this wonderful stone glowed with inconceivable splendour, was so hot that it could not be touched without danger, and that if confined in a close space it would spring with force into the air.
Sometime early in the seventeenth century, a shoemaker of Bologna, one Vincent Cascariolo, who, in addition to his ordinary business dabbled in alchemy, discovered a stone in the neighbourhood of his city which was luminous in the dark. The stone, which is now known to have been a sulphate of barium, and which the shoemaker calcined, ground, and formed into little round discs about the size of a shilling, and sold for a fancy price, was called the sun-stone. The discs, exposed to a strong light for a few minutes and then withdrawn into a dark room, gave out the incandescent light which we know so well. The discovery excited keen interest among scientific men all over Europe.
About 1668 two alchemists named Bauduin and Frueben, who lived at Grossenhayn in Saxony, conceived the idea of extracting by chemical processes the spirit of the world (Spiritus Mundi). Their notion was to combine earth, air, fire, and water in their alembic, and to obtain the essences of all of these in one distillate. They dissolved lime in nitric acid, evaporated to dryness, exposed the residue to the air, and let it absorb humidity. They then distilled this substance and obtained the humidity in a pure form. History does not tell us what questions they put to their spirit of the world when they had thus caught it. It appears, however, that the stuff attained a great sale. It was supplied at 12 groschen the loth, equal to about 1s. 6d.
