Wollaston wire

From Wikipedia, the free encyclopedia

Wollaston wire is an obsolete name for very fine (less than .01 mm thick) platinum wire clad in silver used for electrical instruments around the turn of the 19th century. The term Wollaston wire does not clearly distinguish the bare platinum wire from the composite silver wire with a fine platinum core.

[edit] History

The name refers to the person who developed the early technique for producing such fine wire. Platinum wire was drawn through smaller and smaller dies until it was about .003 inch in diameter. It was then embedded in the middle of a silver wire having a diameter of about one-tenth inch. This composite wire was then drawn until the silver wire had a diameter of about .002 inch. The embedded platinum wire was reduced by the same 50:1 ratio, to a final diameter of .00006 inch (1.5 μm). Removal of the silver coating with an acid bath left the fine platinum wire as a product of the process.

[edit] Uses

Wollaston wire was used in early radio detectors known as electrolytic detectors. Other uses include suspension of delicate devices and sensing of temperature.

Today Wollaston wire is used in temperature sensors and sensitive electrical power measurements.

[edit] Sources

Sources include scientific suppliers[1] where it is extremely expensive.