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The History of Chemistry (Vol.1&2). Thomas Thomson
Читать онлайн.Название The History of Chemistry (Vol.1&2)
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isbn 4064066399887
Автор произведения Thomas Thomson
Жанр Математика
Издательство Bookwire
4. Calais, from the locality and colour was probably the Persian turquoise, as it is generally supposed to be.
5. Whether the prasius and chrysoprasius of Pliny were the modern stones to which these names are given, we have no means of determining. It is generally supposed that they are, and we have no evidence to the contrary.
6. The chrysolite of Pliny is supposed to be our topaz: but we have no other evidence of this than the opinion of M. Du Tems.
7. Asteria of Pliny is supposed by Saussure to be our sapphire. The lustre described by Pliny agrees with this opinion. The stone is said to have been very hard and colourless.
8. Opalus seems to have been our opal. It is called, Pliny says, pæderos by many, on account of its beauty. The Indians called it sangenon.
9. Obsidian was the same as the mineral to which we give that name. It was so called because a Roman named Obsidianus first brought it from Egypt. I have a piece of obsidian, which the late Mr. Salt brought from the locality specified by Pliny, and which possesses all the characters of that mineral in its purest state.
10. Sarda was the name of carnelian, so called because it was first found near Sardis. The sardonyx was also another name for carnelian.
11. Onyx was a name sometimes given to a rock, gypsum; sometimes it was a light-coloured chalcedony. The Latin name for chalcedony was carchedonius, so called because Carthage was the place where this mineral was exposed to sale. The Greek name for Carthage was Καρχηδων (carchedon).
12. Carbunculus was the garnet; and anthrax was a name for another variety of the same mineral.
13. The oriental amethyst of Pliny was probably a sapphire. The fourth species of amethyst described by Pliny, seems to have been our amethyst. Pliny derives the name from α (a) and μυθη (mythe), wine, because it has not quite the colour of wine. But the common derivation is from α and μυθυω, to intoxicate, because it was used as an amulet to prevent intoxication.
14. The sapphire is described by Pliny as always opaque, and as unfit for engraving on. We do not know what it was.
15. The hyacinth of Pliny is equally unknown. From its name it was obviously of a blue colour. Our hyacinth has a reddish-brown colour, and a great deal of hardness and lustre.
16. The cyanus of Pliny may have been our cyanite.
17. Astrios agrees very well, as far as the description of Pliny goes, with the variety of felspar called adularia.
18. Belioculus seems to have been our catseye.
19. Lychnites was a violet-coloured stone, which became electric by heat. Unless it was a blue tourmalin, I do not know what it could be.
20. The jasper of the ancients was probably the same as ours.
21. Molochites may have been our malachite. The name comes from the Greek word μολοχη, mallow, or marshmallow.
22. Pliny considers amber as the juice of a tree concreted into a solid form. The largest piece of it that he had ever seen weighed 13 lbs. Roman weight, which is nearly equivalent to 9¾ lbs. avoirdupois. Indian amber, of which he speaks, was probably copal, or some transparent resin. It may be dyed, he says, by means of anchusa and the fat of kids.
23. Lapis specularis was foliated sulphate of lime, or selenite.
24. Pyrites had the same meaning among the ancients that it has among the moderns; at least as far as iron pyrites or bisulphuret of iron is concerned. Pliny describes two kind of pyrites; namely, the white (arsenical pyrites), and the yellow (iron pyrites). It was used for striking fire with steel, in order to kindle tinder. Hence the name pyrites or firestone.
25. Gagates, from the account given of it by Pliny, was obviously pit-coal or jet.
26. Marble had the same meaning among the ancients that it has among the moderns. It was sawed by the ancients into slabs, and the action of the saw was facilitated by a sand brought for the purpose from Ethiopia and the isle of Naxos. It is obvious that this sand was powdered corundum, or emery.
27. Creta was a name applied by the ancients not only to chalk, but to white clay.
28. Melinum was an oxide of iron. Pliny gives a list of one hundred and fifty-one species of stones in the order of the alphabet. Very few of the minerals contained in this list can be made out. He gives also a list of fifty-two species of stones, whose names are derived from a fancied resemblance which the stones are supposed to bear to certain parts of animals. Of these, also, very few can be made out.
XI.—MISCELLANEOUS OBSERVATIONS.
The ancients seem to have been ignorant of the nature and properties of air, and of all gaseous bodies. Pliny’s account of air consists of a single sentence: “Aër densatur nubibus; furit procellis.” “Air is condensed in clouds, it rages in storms.” Nor is his description of water much more complete, since it consists only of the following phrases: “Aquæ subeunt in imbres, rigescunt in grandines, tumescunt in fluctus, præcipitantur in torrentes.”95 “Water falls in showers, congeals in hail, swells in waves, and rushes down in torrents.” In the thirty-eighth chapter of the second book, indeed, he professes to treat of air; but the chapter contains merely an enumeration of meteorological phenomena, without once touching upon the nature and properties of air.
Pliny, with all the philosophers of antiquity, admitted the existence of the four elements, fire, air, water, and earth; but though he enumerates these in the fifth chapter of his first book, he never attempts to explain their nature or properties. Earth, among the ancients, had two meanings, namely, the planet on which we live, and the soil upon which vegetables grow. These two meanings still exist in common language. The meaning afterwards given to the term, earth, by the chemists, did not exist in the days of Pliny, or, at least, was unknown to him; a sufficient proof that chemistry, in his time, had made no progress as a science; for some notions respecting the properties and constituents of those supposed four elements must have constituted the very foundation of scientific chemistry.
The ancients were acquainted with none of the acids which at present constitute so numerous a tribe, except vinegar, or acetic acid; and even this acid was not known to them in a state of purity. They knew none of the saline bases, except lime, soda, and potash, and these very imperfectly. Of course the whole tribe of salts was unknown to them, except a very few, which they found ready formed in the earth, or which they succeeded in forming by the action of vinegar on lead and copper. Hence all that extensive and most important branch of chemistry, consisting of the combinations of the acids and bases, on which scientific chemistry mainly depends, must have been unknown to them.
Sulphur occurring native in large quantities, and being remarkable for its easy combustibility, and its disagreeable smell when burning, was known in the very earliest ages. Pliny describes four kinds of sulphur, differing from each other, probably, merely in their purity. These were 1. Sulphur vivum, or apyron. It was dug out of the earth solid, and was doubtless pure, or nearly so. It alone was used in medicine. 2. Gleba—used only by fullers. 3. Egula—used also by fullers. Pliny says, it renders woollen stuffs white and soft. It is obvious from this, that the ancients knew the method of bleaching