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Method of checking the purity of gold (3rd c. B.C.)

When the tyrant of Syracuse, Hieron II, received the golden crown which he had ordered from a goldsmith, he suspected that pure gold was not used in its manufacture. He, therefore, assigned Archimedes the inspection of the crown. Archimedes, trying to find a way of determining the purity of the golden crown, without damaging it, devised (in his bathtub according to tradition) the law of specific weight and the principle of buoyancy. He, thus, accomplished to resolve the problem and enthusiastically ran out in the streets naked shouting, “Eureka, Eureka!” (“I have found it! I have found it!”). Practically, Archimedes probably initially counterbalanced the crown in the air with equal mass of pure gold and afterwards immersed the scales in water. The scales did not balance once again as it would be supposed, but tilted towards the mass of pure gold, revealing the fraud of the goldsmith, that is to say, the gold had been adulterated with lighter silver.

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