tailieunhanh - An Encyclopedia of the History of Technology part 24

An Encyclopedia of the History of Technology part 24. This one of a kind encyclopedia presents the entire field of technology from rudimentary agricultural tools to communication satellites in this first of its kind reference source. Following an introduction that discusses basic tools, devices, and mechanisms, the chapters are grouped into five parts that provide detailed information on materials, power and engineering, transportation, communication and calculation, and technology and society, revealing how different technologies have together evolved to produce enormous changes in the course of history | PART ONE MATERIALS thus speed drilling. It also enabled rock samples to be removed to reveal the structures of underground formations and so assist prospecting. Drilling bits were first of wrought iron with steel cutting edges but these were replaced by cast steel bits and then diamond drills introduced by the French in the 1860s. The crude oil was heated to yield useful products by means of distillation a process long familiar to chemists. Further refining was achieved by treatment with various chemicals such as sulphuric acid or caustic soda. The most volatile fraction of the oil to distil over first was petroleum or gasoline for which at first there was no use indeed it was a nuisance because it was highly inflammable. The second fraction boiling at 160-250 C was paraffin kerosene and for the rest of the nineteenth century this was the useful product as an illuminant. The final or heavy fraction became valuable as a lubricant replacing the animal and vegetable oils that had previously satisfied the ever-increasing lubrication demands of machinery of all kinds. The invention of the motor car changed the balance now it was the light petrol fraction that was in demand leading to rapid expansion of the petroleum industry. To boost petrol production cracking was introduced and became widespread during the late 1920s. Here the heavier are converted into the lighter fractions by subjecting them to high temperature and pressure to break down the chains of carbon atoms into shorter ones. On the other hand lighter gaseous products can be formed in the presence of catalysts into motor fuel as in platforming or re-forming with a platinum catalyst. A small but extremely important proportion of the output about 1 per cent is a source of organic chemicals by 1900 it had accounted for a third of the organic chemical industry. Before the First World War the petrochemical industry produced mainly simple olefins such as ethylene and its derivatives including ethylene glycol the .