Page:Popular Science Monthly Volume 43.djvu/100

90 the elixirs, but they also made it practicable to collect the liquids placed in the alembics.

At last, however, the operators of the middle ages perceived that the manipulations could be conducted more rapidly, the distillations, for instance, by cooling the cap and the connected tube that conducted to the last receiver. For that purpose they first fixed around the boiler cap a bucket filled with cold water; this facilitated the condensation, but caused a part of the liquefied vapors to fall back into the boiler. A new improvement—the one described by Porta—consisted in bending the tube between the cap and the receiver and giving it the form of a serpent. This was the origin of the modern still-worm. It was surrounded by cold water in a wooden vessel. But the use of the serpentine arrangement spread very slowly, and was still regarded as recent by the authors of the eighteenth century.

Let us observe here that we are using the word distillation in the modern sense of evaporation followed by a condensation of liquid; but in many authors of the middle ages the sense is more vague. The word means, in its literal sense, a flow drop by drop, and is applied equally to filtration and all refining and purification. The word distill is often employed in the same sense in modern language. It also comprehended from the Greco-Egyptian epoch two fundamentally distinct operations, viz., the condensation of dry vapors into a solid form—such as calamines or metallic oxides, sulphur, metallic sulphurets, arsenious acid and metallic arsenic (which was the second mercury of the Grecian alchemists), and at a later date chlorides of mercury, sal ammoniac, etc.—the process which is now called sublimation. It requires special apparatus, which the ancients devised and used, and which gave rise to the Arabian aludel. We mention this here on account of its connection with many modern industries, although it has no relation to the discovery of alcohol.

I proceed now to describe distilled liquids and the successive steps made in their study. "Celestial things above, terrestrial things below," was the phrase by which the Grecian alchemists designated the products of all distillation and sublimation. They declared that "the sublimed vapor emitted from below up is called divine. . . . White mercury is likewise called divine, because it, too, is emitted from below up. . . . The drops which affix themselves to the covers of boilers are likewise called divine." In this expression we find the marks of Aristotle, Dioscorides, and Alexander of Aphrodisias. The alchemists, according to their usage, interpreted these purely physical ideas by symbols and a curious mysticism. Democritus (or the alchemic author who took that name) called the spherical apparatus in which the distillation of water was carried on "celestial natures."