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Volume 15, Number 3May/June 1964

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The Chemist Of Hit

A look into a Middle Eastern lab 3,500 years ago reveals apparatus and techniques still not out of date.

Written by The Editors

On the west bank of the Euphrates, almost one hundred miles due west of the fabled Baghdad, stands the equally eternal city of Hit.

As a city-site, Hit was already old that summer's afternoon 3,500 years ago, when a strange thing happened in the laboratory of Tiglaser, the most respected chemist between Nineveh and Babylon.

Tiglaser was in the yard outside the laboratory building, supervising the first stages of the manufacture of lead acetate. The concentrated solution of vinegar had just begun its brisk and bubbling attack upon the beaten sheets of lead when an explosion from somewhere inside the laboratory cracked against the scientist's eardrums and threw a blast of hot air across his face.

His first thought was of Telrid, his laboratory assistant and apprentice. He hurried into the laboratory and into a mist of acrid fumes of burning sulphur and pitch. His eyes smarted as he saw the boy near the window, pouring water on to a lump of flaming bitumen the size of a man's fist.

"Sand!" shouted the scientist. "Use sand. Water will only spread the fire!"

When the apprentice had brought sand from the yard and quenched the blaze, the chemist asked him what had happened. "Sir," said the boy, "it was this thick piece of clear glass. I thought to experiment with it and held it between the sun and this lump of bitumen. The sunlight came through the glass and pierced the pitch with a single point of blinding brilliance, melting a spot on it till it bubbled, hissed and ran. A moment later—the explosion!"

The boy's eyes shone with excitement. He was neither afraid of his recent danger nor apologetic to his master. The elation of discovery filled him. He asked what had caused the explosion.

Tiglaser told him of the gas that issued from heated bitumen. "It is called 'naptu' and means 'to blaze up'. It is very dangerous and must be distilled out of all bitumen in the open air, so that it will blow away. Naptu is difficult for us to control, but we shall master it one day."

The apprentice was far away in the visions of his mind. "Such power," he said. "Such great power!"

"You have not been with me long, young man," said the scientist, "and so I must warn you in laboratory matters. It is well to experiment, to inquire of nature's mysteries. But one must seek with care and respect—approach nature aright and you will be well rewarded with sweet knowledge. Search with haste and clumsiness, and you will loose a tiger upon your head."

Tiglaser was a wise man, revered in all that land for his wisdom and respected for his great learning. He saw that the boy was full of wonder, and he decided that now was the time to show the apprentice the full range of chemistry in the laboratory's activities.

The scientist began with showing the boy the blast furnaces in which glass was made and colored brilliantly. Mesopotamia was certainly one of the first countries to make glass and the first to develop the means of heating the sand and natron mixture from an open hearth-type fire to the early equivalent of a blast furnace. The hearth-type had used mainly animal waste as fuel, but it was discovered that the addition of common salt raised the temperature greatly by a process of catalysis (to about 830 Centigrade degrees). Keen observers had at first increased this heat again by the use of reed blowpipes to blow air into the glowing fuel, and this was advanced by a few stages to the kiln type of furnace, built of stone and fired from an external chamber, the heat being blown into the kiln by hand-operated bellows. The bellows consisted of clay tubes fitted with fine animal skin blowers, and were the prototype of those in use today.

The chemist laid his hand paternally on the boy's shoulder. "In the sciences, of which chemistry is only one," he said, "we can do nothing unless we first design and make equipment in order to change nature's substances to our wishes." He then began to show the apprentice certain objects which had originated in Mesopotamia.

There were the pestle and mortar, of which six sets rested on a wooden bench in the laboratory. Two sets were made of flinty quartzite for crushing the hardest substances, two of bronze, one of soft limestone, and a delicately-made set of fired clay. The bowl-shaped mortar and the club-shaped pestle were of almost exactly the same design as those to be used by Western countries many centuries later, when the alchemists searched for the magic stone.

On the far left of the same bench, which was used mainly as a storing place for apparatus, were a number of clay and glass beakers and crucibles, clean, dry, and ready for use. The beakers, tall, broad-based, and each with a lip for pouring; and the crucibles, shallow and wide, and also with pouring lips, were of designs which were to spread later along the whole length of the Mediterranean to Europe and America without any significant change, because the originals could not be improved upon. The beakers were marked with graduated levels for exact measurement of fluids.

Tiglaser took up one of the graduated beakers and pointed out the marks which indicated steps of from ⅛  of a log up to 1 log (about one pint). He then showed Telrid a set of standard weights made of highly polished stone so that they would resist wear. These weights were made in the form of ducks asleep and lay along the foot of a delicately made balance with beam and pans of wood.

"In chemistry," said the scientist, "it is of the greatest importance to know exactly how much of the chemicals you use in any operation. This is so that you may repeat the same operation any number of times should you wish to do so. This step is indispensable in applied chemistry such as in our chemical manufacturing activities here."

Standing on the floor in one corner of the laboratory were a number of large, wide-mouthed jars, each containing crystals of different shapes and angles of diffraction.

These chemicals were mainly sodium chloride, alum, sodium carbonate or natron, potassium carbonate, ammonium chloride and potassium nitrate. They were found in a variety of ways, from evaporated brine, soil efflorescence, distillation of burning fuels and subsequent condensation of the fumes on cold metal plates, and sometimes they were found in the state of a natural stone, like alum.

Since most of these chemicals looked alike, being white crystalline powders in the pure condition, it was a great problem to the early Middle East scientists to find out how to purify and separate one chemical from another. The problem was solved a thousand years even before Tiglaser's time, and the method—fractional crystallization—is still in full use today in advanced laboratories. As an example of the process, the alumstone rock was crushed and boiled in water after being roasted to make it more frangible.

The solution was then concentrated by further boiling and allowed to cool, whereupon crystals of alum formed in clusters in the beakers. Any other chemical in the stone, potassium nitrate for example, also formed crystals, but these were quite different in shape from the alum and thus were easily separated. Further boiling and cooling produced more and more pure chemicals, and this refining was carried out especially in the case of substances to be used in making medicines. The others, used mainly in the manufacture of different grades of glass, did not need nearly as much purification.

There were many other wonders for the apprentice Telrid to study.

In bronze or fired clay vessels that had sieved bottoms, lumps of heavy bitumen were heated and the purified drips collected in drip trays and run into storage containers. Rock sulphur was also treated in this way, and so was history's first "flowers of sulphur" produced. In the case of the more volatile sulphur, the upward-rising fumes condensed on a tray above the material and yielded fine sulphur powder. These methods of early distillation undoubtedly gave rise, later, to modern distillation apparatus.

The apprentice saw the making of many grades of soaps by boiling alkaline plant ashes with various fats and oils. The processes are essentially the same as those used today, and even the name "alkali" is derived from the ancient name of the plant ashes, "kalati."

During the rest of the tour, Telrid watched the production of red lead, made by roasting the vinegar-metallic lead product, lead acetate. This red substance was used for coloring glass and making paints, as was also a green color from malachite; a special blue from oven-roasting copper carbonate and limestone; light ibis-red and vermilion through crimson to the deep black-red of old blood from iron oxides, and, among others, a rich and truly royal purple produced by melting sand with alkali and secret copper salts.

The day waned before all the processes could be shown to the boy.

As Tiglaser was preparing for bed that night, the stars were great in the clear sky. What was it the apprentice had said about the explosion—ah, yes—"Such power! Such great power!"

There was awe in the heart of the Mesopotamian chemist as he looked again at the distant planets, then remembered the many mysteries of his own planet, mysteries he himself tried to sort out in his laboratory. There was so much more to learn.

But this much is sure—the foundations of the chemistry of the twentieth century were laid in the thoughts, the apparatus, and the fundamental techniques of that early day, for Tiglaser and his fellow scientists were true chemists—they pursued honest knowledge and used it for the practical benefit of mankind.

This article appeared on pages 10-12 of the May/June 1964 print edition of Saudi Aramco World.


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