Platinum
Platinum is a silver-grey, lustrous metal element. It has an atomic number of 78, an atomic weight of 195.08, and it is denoted by the atomic symbol, Pt. It melts at 3,215.1°F (1,768.4°C) and boils at about 6,920.6°F (3,827°C). It usually occurs in a native state along with other members of the platinum family: iridium, osmium, palladium, ruthenium, and rhodium.
The first definite mention of platinum occurs in the writings of an Italian physician and poet, Julius Caesar Scalinger. Writing in 1557, he described seeing in mines of South (now Central) America a white metal that "not been possible to melt by fire or by any of the Spanish arts." Miners contemptuously referred to the substance as platina, meaning "little silver." They knew of few uses for the metal and disliked the way it interfered with their recovery of gold.
Apparently native technicians had learned how to work with platinum in spite of its very high melting point. They mixed tiny pieces of the metal into molten gold and then, when the mixture solidified, hammered it into jewelry and ornaments.
Credit for the discovery of the chemical element is usually given to Don Antonio de Ulloa, a young lieutenant in the Spanish navy. In his 1748 account of the fleet's first visits to South America, de Ulloa describes platina, a substance "of such resistance that... [it] could not be extracted without infinite labor and charge."
The first thorough study of platinum was conducted in 1750 by the English physician, William Brownrigg. Brownrigg noted that platinum was heavier and even more chemically inert than was gold. His reports about the new element set off research on the element throughout Europe.
The first pure sample of platinum appears to have been produced by W. H. Wollaston in 1803. Wollaston devoted himself to finding ways of working with this difficult metal and of making laboratory equipment from it. He found that by converting platinum first to a spongy form he could hammer and shape the metal and produce all types of tools and equipment from it. Wollaston was so successful that he made a fortune and was able to retire from his medical practice at the age of 34. Financially self-sufficient, he devoted the rest of his life to scientific research.
Platinum has a great many applications that make use of its chemical inactivity. These include laboratory crucibles, thermometers, electrodes, and wires. Rocket and jet engine parts often contain platinum alloys because they must withstand high temperatures for long periods of time. Platinum is also used extensively as a catalyst in the manufacture of sulfuric acid, acetic acid, nitric acid, in the cracking of petroleum, and in catalytic convertors in automobiles. At high temperatures, it adsorbs large volumes of hydrogen and retains the gas on its surface as it cools to ordinary room temperatures.
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