Rensselaer Republican, Volume 18, Number 44, Rensselaer, Jasper County, 8 July 1886 — Impurities in Metals. [ARTICLE]

Impurities in Metals.

In a recent lecture Mr. W. Rob-erts-Austen, chemist of the British mint, remarked upon the wonderful effects often produced upon metals by minute quantities. Slight impurities in metallic copper would render ocean telegraphy impossible. When purified, tin loses its well-known “cry,” or noise made when bent. A trace of arsenic increases the fluidity of lead so that it will roll itself into small shot in sliding down an inclined plane. Standard gold melts at about 1,660 degree, but if a fifth of one per cent, of silica be added it will soften in a candle-flame. A trace of lead added to gold forms an alloy much dreaded at the mint, the breaking strain of the gold being reduced from twenty tons to five. Some metals have a remarkable power of taking up gases, palladium being capable of absorbing 900 times its volume of hydrogen and giving it out again when heated. A remarkable discovery is that an alloy of rhodium and lead will absorb nitrogen and oxygen, and when heated give them, off with explosive violence as gun-cotton does.