*
[511] I am sorry I cannot remember the initials to this gentleman’s letter, which has been accidentally mislaid.
Discoveries
OF THE
ANCIENTS AND MODERNS.
No. XXXV.
Ancient Chemistry, &c.
Distillation.—It has been questioned whether the ancients were acquainted with this art, but a passage of Dioscorides not only indicates the practice, but shows that the name of its principal instrument, the alembic, was derived from the Greek language. Pliny gives the same explanation, as Dioscorides does, of the manner of extracting quicksilver from cinnabar by distillation. And Seneca describes an instrument exactly resembling the alembic. Hippocrates even describes the process of distillation. He talks of vapours from the boiling fluid, which meeting with resistance stop and condense, till they fall in drops. Zosimus of Panopolis, an Egyptian city, desires his students to furnish themselves with alembics, gives them directions how to use them, describes them, and presents drawings of such as best deserve to be employed in practice.
Alcalis and Acids.—Of the substances promiscuously termed lixivial salt, sal alcali, rock-salt, &c., Aristotle speaks, when he says that in Umbria the burnt ashes of rushes and reeds, boiled in water, yield a great quantity of salt. Theophrastus observes the same. Varro relates of dwellers on the borders of the Rhine, who having neither sea nor pit salt, supply themselves by means of the saline cinders of burnt plants. Pliny speaks of ashes as impregnated with salts, and in particular of the nitrous ashes of burnt oak; adding, that these salts are used in medicine, and that a dose of lixivial ashes is an excellent remedy. Hippocrates, Celsus, Dioscorides, and especially Galen, often recommend the medical use of sal alcali. To the mixture of acids and alcali, Plato ascribed fermentation. Solomon seems to have known this effect of them, when he speaks of “vinegar upon nitre.”
Cleopatra’s Pearl.—A convincing proof of the ability of the ancients in chemistry is the experiment with which Cleopatra entertained Marc Antony, in dissolving before him, in a kind of vinegar, a pearl of very great value, (above 45,450l. sterling.) At present we know not of any “vinegar” that can produce this effect; but the fact is well attested. Probably the queen added something to the vinegar, omitted by the historian. The aid of Dioscorides, surnamed Phacas, who was her physician, might have enabled her thus to gain her wager with Marc Antony, that she would exceed him in the splendour and costliness of her entertainment. But Cleopatra herself was a chemical adept, as appears from some of her performances still in the libraries of Paris, Venice, and the Vatican. And Pliny informs us of the emperor Caius, that by means of fire he extracted some gold from orpiment.
Malleability of Glass.—The method of rendering glass ductile, which is to us a secret, was assuredly a process well known to the ancients. Some still doubt of it, as others have of the burning glasses of Archimedes. Because forsooth they do not know how it could be effected, they will not admit the fact, notwithstanding the exact accounts we have of it, till somebody again recovers this lost or neglected secret, as Kircher and Buffon did that of Archimedes’s mirrors. Pliny says, the flexibility of glass was discovered in the time of Tiberius; but that the emperor fearing lest gold and silver, those most precious metals, should thereby fall in their value, so as to become contemptible, ordered the residence, workhouse, and tools of the ingenious artisan to be destroyed, and thus strangled the art in its infancy. Petronius is more diffuse. He says, that in the time of Tiberius there was an artificer who made vessels of glass, which were in their composition and fabric as strong and durable as silver or gold; and that being introduced into the presence of the emperor, he presented him with a vase of this kind, such as he thought worthy of his acceptance. Meeting with the praise his invention deserved, and finding his present so favourably received, he threw the vase with such violence upon the floor, that had it been of brass it must have been injured by the blow; he took it up again whole, but dimpled a little, and immediately repaired it with a hammer. While in expectation of ample recompense for his ingenuity, the emperor asked him whether any body else was acquainted with this method of preparing glass, and being assured that no other was, the tyrant ordered his head to be immediately struck off; lest gold and silver, added he, should become as base as dirt. Dion Cassius, on this head, confirms the attestations of Pliny and Petronius. Ibn Abd Alhokim speaks of malleable glass as a thing known in the flourishing times of Egypt. Greaves, in his work on Pyramids, mentions him as a celebrated chronologist among the Arabians, and cites from him that “Saurid built in the western pyramid thirty treasuries, filled with store of riches and utensils, and with signatures made of precious stones, and with instruments of iron and vessels of earth, and with arms which rust not, and with glass which might be bended, and yet not broken, &c.” There is, however, a modern chemical composition, formed of silver dissolved in acid spirits, and which is called cornu lunæ, or horned moon, a transparent body, easily put into fusion, and very like horn or glass, and which will bear the hammer. Borrichius, a Danish physician of the seventeenth century, describes an experiment of his own, by which he obtained a pliant and malleable salt: he gives the receipt, and concludes from thence, that as glass for the most part is only a mixture of salt and sand, and as the salt may be rendered ductile, glass may be made malleable: he even imagines that the Roman artificer, spoken of by Pliny and Petronius, may have successfully used antimony as the principal ingredient in the composition of his vase. Descartes supposed it possible to impart malleability to glass, and Morhoff assures us that Boyle was of the same opinion.