Page:Popular Science Monthly Volume 16.djvu/524

498 1315 ). In his works we find the following characteristic passage: "Take, in the Name of God, great Bay Salt, as it is made out of the Sea; take a good quantity and stamp very small into a stone-morter: then take Cucurbites of Glass and pour your Salt therein: then take fair Well-water, and let your salt resolve into cleer water; being all dissolved then distil it by Filter; that is to say, hang a jag Felt or Woolen cloath in the Cucurbite; and let the other end hang in another Glass beside it, set as it were under it, that the water may drop into it that the Felt or Cloath may draw out and that shall be cleer as silver."

This unmistakable description of anethisis occurs in the first chapter of a booklet bearing the following title: "Philosophical and Chymical Experiments of the Famous Philosopher Raymund Lulli. . . . wherein is contained. . . . the admirable and perfect way of making the great Stone of the Philosophers as. . . . sometimes practised in England by Raymund Lulli in the time of King Edward the Third." London, 1657.

Thomas Aquinas, the eminent scholastic teacher of the thirteenth century, who is best known by his theological and metaphysical works, also paid some attention to scientific pursuits, possibly acquiring this taste from his learned master, Albertus Magnus. Aquinas, or the divine Thomas, as he was called by his admirers, defines distillation to be the "purification of waters falling drop by drop, and effected by placing a filter cut in the shape of an iron dart in the little dish containing the water to be distilled."

Libavius, in his remarkable work, "Alchymia," sometimes called the first text-book of chemistry (published in 1595), devotes two entire chapters to the subjects of distillation and of filtration. In the fourteenth chapter he describes, with much attention to detail, the manner of filtering by means of pieces of felt (lacinia) shaped like an ox-tongue, the broader portion of which is placed in the vessel containing the liquid to be filtered, and "the apex in the recipient, or, if the vessel has a narrower neck, in a suitable funnel." This demonstrates that the method was not resorted to on account of the want of proper funnels, and suggests that perhaps a special virtue was attributed to a liquid thus purified.

Libavius's work contains rude woodcuts illustrating different methods of procedure. For perfecting the purification a series of four vessels was used. These were placed on steps, one above another, and the liquid passed through a capillary siphon from the uppermost to the one immediately below, and thence by another siphon to the third vessel, and so on to the fourth. This series of vessels can be inclosed in a glass-covered box for filtering volatile liquids. Another woodcut represents the lower end of a capillary siphon hanging into a