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. per ounce, and lords and peasants came after it eagerly. Rain-water would have been just as good, Kunckel, who tells the story, remarks. But one day Bauduin broke one of the vessels in which was contained some of the calcined nitrate of lime, and he observed that this, like the Bologna stone, was luminous in the dark after exposure to sunlight. Bauduin appreciated the importance of his discovery, and, taking some of his earth to Dresden, talked about it there. Kunckel, who was then the Elector’s pharmacist, and keenly interested in new discoveries, heard about this curious substance, and was very curious to find out all he could. He visited Bauduin and tried to draw from him the details of his process. But Bauduin was very shy of Kunckel, and the latter has left an amusing account of an evening he spent with his quarry. Kunckel tried to talk chemistry, but Bauduin would only take interest in music. At last, however, Kunckel induced Bauduin to go out of the room to fetch a concave mirror to see if with that the precious phosphorus (for Bauduin had already appropriated this name to the stuff) would absorb the light. While Bauduin was gone Kunckel managed to nip a morsel with his finger-nail. With this, aided by the fragments of information he had been able to steal from Bauduin’s conversation, he commenced to experiment by treating chalk with nitric acid, and ultimately succeeded in producing the coveted luminous earth. He sent a little lump of it to Bauduin as an acknowledgment of the pleasant musical evening the latter had given him.