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Kirkendall effect. The Kirkendall effect is the motion of the interface between two metals that occurs due to the difference in diffusion rates of the metal atoms. The effect can be observed for example by placing insoluble markers at the interface between a pure metal and an alloy containing that metal, and heating to a temperature where ...
Philosopher's stone. The Alchymist, in Search of the Philosopher's Stone by Joseph Wright of Derby, 1771. The philosopher's stone[ a] is a mythic alchemical substance capable of turning base metals such as mercury into gold or silver [ b]; it was also known as "the tincture" and "the powder". Alchemists additionally believed that it could be ...
A RYB color wheel with tertiary colors described under the modern definition. RYB is a subtractive mixing color model, used to estimate the mixing of pigments (e.g. paint) in traditional color theory, with primary colors red, yellow, and blue. The secondary colors are green, purple, and orange as demonstrated here: red.
Purple is a color similar in appearance to violet light. In the RYB color model historically used in the arts, purple is a secondary color created by combining red and blue pigments. In the CMYK color model used in modern printing, purple is made by combining magenta pigment with either cyan pigment, black pigment, or both.
An Act to Provide For a Copper Coinage. On May 8, 1792, An Act to Provide For a Copper Coinage [1 Stat. 283 ]] was signed into law by President George Washington. It followed the precedent of the Fugio cent of 1787 in establishing the copper cent, from which descends today's one-cent piece. The Act also stipulated that "the director of the mint ...
Gold often occurs in free elemental ( native state ), as nuggets or grains, in rocks, veins, and alluvial deposits. It occurs in a solid solution series with the native element silver (as in electrum ), naturally alloyed with other metals like copper and palladium, and mineral inclusions such as within pyrite.
Their name for brass was orichalcum, also spelled aurichalcum (echoing the word for a gold coin, aureus), meaning 'gold-copper', because of its shiny, gold-like appearance when the coins were newly struck (see, for example Pliny the Elder in his Natural History Book 34.4). Orichalcum was considered, by weight, to be about double the value of ...
Pure gold is slightly reddish yellow in color, [ 1] but colored gold can come in a variety of different colors by alloying it with different elements. Colored golds can be classified in three groups: [ 2] Alloys with silver and copper in various proportions, producing white, yellow, green and red golds. These are typically malleable alloys.