Friday, September 26, 2008

Foundation of Designer Perfumes

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As with industry and the arts, perfume was to go through profound change in the nineteenth century. Changing tastes and the growth of modern chemistry laid the foundations of perfumery as we know it today. Alchemy gave way to chemistry and new fragrances were produced. The French Revolution had in no way diminished the flavor for perfume, there was even a fragrance called "Parfum a la Guillotine." Under the post-revolutionary government, people once again dared to convey a penchant for luxury goods, including perfume. A large amount of vanity boxes containing perfumes appeared in the 19th century.

Wednesday, September 10, 2008

Diamonds formed in cratons

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The conditions for diamond formation to happen in the lithospheric mantle occur at large depth corresponding to the aforementioned requirements of temperature and pressure. These depths are estimated to be in between 140–190 kilometers (90–120 miles) though rarely diamonds have crystallized at depths of 300-400 km (180-250 miles) as well. The rate at which temperature changes with rising depth into the Earth varies greatly in different parts of the Earth. In particular, under oceanic plates the temperature rises more rapidly with depth, beyond the range required for diamond formation at the depth required. The correct mixture of temperature and pressure is only found in the thick, ancient, and stable parts of continental plates where regions of lithosphere known as cratons exist. Long residence in the cratonic lithosphere allows diamond crystals to develop larger.