The History of Chemistry (Vol.1&2) - Thomas Thomson

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of the plain.

       Then emulous the royal robes they lave,

       And plunge the vestures in the cleansing wave.

       Odyssey, vi. 1. 99.

      We find, in some of the comic poets, that the Greeks were in the habit of adding wood-ashes to water to make it a better detergent. Wood-ashes contain a certain portion of carbonate of potash, which of course would answer as a detergent; though, from its caustic qualities, it would be injurious to the hands of the washerwomen. There is no evidence that carbonate of soda, the nitrum of the ancients, was ever used as a detergent; this is the more surprising, because we know from Pliny that it was employed in dyeing, and one cannot see how a solution of it could be employed by the dyers in their processes without discovering that it acted powerfully as a detergent.

      The word soap (sapo) occurs first in Pliny. He informs us that it was an invention of the Gauls, who employed it to render their hair shining; that it was a compound of wood-ashes and tallow, that there were two kinds of it, hard and soft (spissus et liquidus); and that the best kind was made of the ashes of the beech and the fat of goats. Among the Germans it was more employed by the men than the women.88 It is curious that no allusion whatever is made by Pliny to the use of soap as a detergent; shall we conclude from this that the most important of all the uses of soap was unknown to the ancients?

      It was employed by the ancients as a pomatum; and, during the early part of the government of the emperors, it was imported into Rome from Germany, as a pomatum for the young Roman beaus. Beckmann is of opinion that the Latin word sapo is derived from the old German word sepe, a word still employed by the common people of Scotland.89

      It is well known that the state of soap depends upon the alkali employed in making it. Soda constitutes a hard soap, and potash a soft soap. The ancients being ignorant of the difference between the two alkalies, and using wood-ashes in the preparation of it, doubtless formed soft soap. The addition of some common salt, during the boiling of the soap, would convert the soft into hard soap. As Pliny informs us that the ancients were acquainted both with hard and soft soap, it is clear that they must have followed some such process.

      VII.—STARCH.

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      The manufacture of starch was known to the ancients. Pliny informs us that it was made from wheat and from siligo, which was probably a variety or sub-species of wheat. The invention of starch is ascribed by Pliny to the inhabitants of the island of Chio, where in his time the best starch was still made. Pliny’s description of the method employed by the ancients of making starch is tolerably exact. Next to the China starch that of Crete was most celebrated; and next to it was the Egyptian. The qualities of starch were judged of by the weight; the lightest being always reckoned the best.

      VIII.—BEER.

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      That the ancients were acquainted with wine is universally known. This knowledge must have been nearly coeval with the origin of society; for we are informed in Genesis that Noah, after the flood, planted a vineyard, and made wine, and got intoxicated by drinking the liquid which he had manufactured.90 Beer also is a very old manufacture. It was in common use among the Egyptians in the time of Herodotus, who informs us that they made use of a kind of wine made from barley, because no vines grew in their country.91 Tacitus informs us, that in his time it was the drink of the Germans.92 Pliny informs us that it was made by the Gauls, and by other nations. He gives it the name of cerevisia or cervisia; the name obviously alluding to the grain from which it was made.

      But though the ancients seem acquainted with both wine and beer, there is no evidence of their having ever subjected these liquids to distillation, and of having collected the products. This would have furnished them with ardent spirits or alcohol, of which there is every reason to believe they were entirely ignorant. Indeed, the method employed by Dioscorides to obtain mercury from cinnabar, is a sufficient proof that the true process of distillation was unknown to them. He mixed cinnabar with iron filings, put the mixture into a pot, to the top of which a cover of stoneware was luted. Heat was applied to the pot, and when the process was at an end, the mercury was found adhering to the inside of the cover. Had they been aware of the method of distilling the quicksilver ore into a receiver, this imperfect mode of collecting only a small portion of the quicksilver, separated from the cinnabar, would never have been practised. Besides, there is not the smallest allusion to ardent spirits, either in the writings of the poets, historians, naturalists, or medical men of ancient Greece; a circumstance not to be accounted for had ardent spirits been known, and applied even to one-tenth of the uses to which they are put by the moderns.

      IX.—STONEWARE.

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      The manufacture of stoneware vessels was known at a very early period of society. Frequent allusions to the potter’s wheel occur in the Old Testament, showing that the manufacture must have been familiar to the Jewish nation. The porcelain of the Chinese boasts of a very high antiquity indeed. We cannot doubt that the processes of the ancients were similar to those of the moderns, though I am not aware of any tolerably accurate account of them in any ancient author whatever.

      Moulds of plaster of Paris were used by the ancients to take casts precisely as at present.93

      The sand of Puzzoli was used by the Romans, as it is by the moderns, to form a mortar capable of hardening under water.

      Pliny gives us some idea of the Roman bricks, which are known to have been of an excellent quality. There were three sizes of bricks used by the Romans.

      1. Lydian, which were 1½ foot long and 1 foot broad.

      2. Tetradoron, which was a square of 16 inches each side.

      3. Pentadoron, which was a square, each side of which was 20 inches long.

      Doron signifies the palm of the hand: of course it was equivalent to 4 inches.

      X.—PRECIOUS STONES AND MINERALS.

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      Pliny has given a pretty detailed description of the precious stones of the ancients; but it is not very easy to determine the specific minerals to which he alludes.

      1. The description of the diamond is tolerably precise. It was found in Ethiopia, India, Arabia, and Macedonia. But the Macedonian diamond, as well as the adamas cyprius and siderites, were obviously not diamonds, but soft stones.

      2. The emerald of the ancients (smaragdus) must have varied in its nature. It was a green, transparent, hard stone; and, as colour was the criterion by which the ancients distinguished minerals and divided them into species, it is obvious that very different minerals must have been confounded together, under the name of emerald. Sapphire, beryl, doubtless fluor spar when green, and probably even serpentine, nephrite, and some ores of copper, seem to have occasionally got the same name. There is no reason to believe that the emerald of the moderns was known before the discovery of America. At least it has been only found in modern times in America. Some of the emeralds described by Pliny as losing their colour by exposure to the sun, must have been fluor spars. There is a remarkably deep and beautiful green fluor spar, met with some years ago in the county of Durham, in one of the Weredale mines that possesses this property. The emeralds of the ancients were of such a size (13½ feet, large enough to be cut into a pillar), that we can consider them in no other light than as a species of rock.

      3.

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