Wollaston wire is a very fine (less than 0.01 mm thick)

platinum Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver". Pla ...

wire Overhead power cabling. The conductor consists of seven strands of steel (centre, high tensile strength), surrounded by four outer layers of aluminium (high conductivity). Sample diameter 40 mm A wire is a flexible strand of metal. Wire is c ...

clad in

silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...

and used in electrical instruments. For most uses, the silver cladding is etched away by acid to expose the platinum core.

History

The wire is named after its inventor,

William Hyde Wollaston William Hyde Wollaston (; 6 August 1766 – 22 December 1828) was an English chemist and physicist who is famous for discovering the chemical elements palladium and rhodium. He also developed a way to process platinum ore into malleable ingot ...

, who first produced it in England in the early 19th century. Platinum wire is drawn through successively smaller dies until it is about in diameter. It is then embedded in the middle of a silver wire having a diameter of about . This composite wire is then drawn until the silver wire has a diameter of about , causing the embedded platinum wire to be reduced by the same 50:1 ratio to a final diameter of . Removal of the silver coating with an acid bath leaves the fine platinum wire as a product of the process.

Uses

Wollaston wire was used in early radio

detectors A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...

known as

electrolytic detector The electrolytic detector, or liquid barretter, was a type of detector (demodulator) used in early radio receivers. First used by Canadian radio researcher Reginald Fessenden in 1903, it was used until about 1913, after which it was superseded ...

s Lee, T. H., ''The design of CMOS radio-frequency integrated circuits'', 2nd edition, Cambridge University Press, 2004, p. 8. and the hot wire barretter. Other uses include suspension of delicate devices, sensing of temperature, and sensitive electrical power measurements. It continues to be used for the fastest-responding hot-wire anemometers.

References

{{Electronic components History of radio Radio electronics Wire