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1. VI.

SCIENCE OF THE ARABS.

39

CHAPTER VI.

SCIENCE OF THE ARABS.

Dark Ages of Europe-Taking of Alexandria by the Araos and burning of the Library-The Arabs, checked in their conquests by Charles Martel, settle down to Science-The Nestorians and Jews translate Greek Works on Science-Universities of the Arabs-Chemistry first studied by the Arabs Alchemy, or the attempt to make Gold - Hermes the first Alchemist - Hermetically-sealed TubesGases and Vapours called 'Spirits' by the Arabs-The use of this Word retained by us.

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Arabian Science. We have now arrived at what have been called the "Dark Ages,' because for several hundred years Europe was too much engaged in wars and disputes to pay any attention to learning or science. You have, no doubt, read in history how the Goths and Vandals, a barbarous people from north-eastern Asia, spread themselves over Europe, conquering the Romans, and taking possession of all their colonies. They even crossed over into Africa, but were driven out again by the famous General Belisarius, in the reign of Justinian, Emperor of Constantinople. This was in the year A.D. 534, and the Romans held Alexandria again for about one hundred years, and then came the Arabs or Saracens, pouring out of Arabia, and they took possession of Alexandria in the year A.D. 639, only seven years after the death of their great leader Mahomet.

The first thing they did on taking the city was to burn the famous library of Alexandria, and it seemed as if they

were going to destroy the last remnant of the science of the Greeks. But it proved otherwise they went on conquering and destroying till they had overrun all the north of Africa up to the Straits of Gibraltar, had taken a great part of Spain and even of the south of France as far as the river Aude, in Languedoc, and then when Charles Martel, mayor of the Franks, conquered them at Tours in 732, and stopped them from going any farther, they settled down and began to give their attention to science and learning.

They found in Arabia and in Egypt two classes of people who were able to teach them the science of the Greeks. These were the Nestorians and the Jews. The Nestorians, or followers of Nestorius, Bishop of Constantinople, were a peculiar sect of Christians, who had fled into Arabia about the year 450, that they might found a Church of their own. They became very powerful and learned, and translated many of the Greek works of science into the Arabian language. The Jews, after the fall of Jerusalem, had also taken refuge in Syria and Mesopotamia, and they were very skilful in medicine, and founded many medical colleges. The Arabian schools of Bagdad, Cairo, Salerno in the south of Italy, and Cordova in Spain, soon became famous all over the world. The Arabs were not able to practise anatomy in their medical schools, because the Koran, that is the Mahommedan Bible, taught that it was not right to dissect the human body, so they turned their attention chiefly to medicine, trying to discover what substances they could extract from plants and minerals, at first to serve as medicines but soon for very different uses.

Arabian Alchemists.-They found something in the old Greek writings about the way to melt stones or minerals, so as to get out of them iron, mercury, and other metals; and

CH. VI.

ARABIAN ALCHEMISTS.

41

also how to extract many beautiful colours out of rocks and earths. But the chief thing which interested them in the books of the Egyptians, Chaldeans, and Greeks, was the attempts these nations had made to turn other metals into gold, a discovery which tradition said had been made by Hermes Trismegistus about 2,000 years before Christ. We know very little of this Hermes, and indeed we are not sure whether he is not altogether an imaginary person; but the alchemists, as the people were called who tried to make gold, considered themselves followers of Hermes, and often called themselves Hermetic philosophers. To melt the mouth of a glass tube so as to close it was called securing it with 'Hermes, his seal,' and even to this day a bottle or jar which is closed so that it is air-tight is said to be hermetically sealed.

The Arabs were a very superstitious people, and believed in all kinds of charms; and this idea of making gold in a mysterious way took a great hold of them. Many thousands. of clever men occupied themselves in the supposed magic art of alchemy. We need not study it here, but only observe how very useful it was in teaching the first facts of chemistry. These men, who were many of them learned, clever, and patient, spent their lives in melting up different substances and watching what changes took place in them. In this way they learnt a great deal about the materials of which rocks, minerals, and other substances are made.

One of the first things they discovered was that by heating some substances, such as nitre or saltpetre, they drove something out of them which was invisible, and yet that they could collect this invisible something in bottles; and in some cases, if they put a light to it, it exploded violently, breaking the bottle to atoms. Now, because this was invisible and yet so powerful, they thought it must be

like the spirit of man, which can do so much and yet cannot be seen, and for this reason they called it 'spirit.' We know now that when we heat substances we separate part of the matter of which they are made into very small portions, which float off as steam or gas into the air; so that this spirit noticed by the Arabs was vapour or gas.

It seems almost certain that the Arabs knew a great deal about gunpowder and some other mixtures which explode when they are set on fire. An Arab named Marcus Græcus, who lived about the beginning of the ninth century, says that if you mix together one pound of sulphur, two of charcoal, and six of saltpetre, it will explode when you light it and drive things into the air. This is one of the ways in which gunpowder is still made.

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