Arcane: Platinum gas lighter’s

This isn’t exactly arcane knowledge, so much as neglected knowledge.

That it’s neglected is even more bemusing with the advent of catalytic converter’s in cars.

(I was intrigued by Stephen Fry’s assertion, on QI, that the dust on our streets contain platinum at commercially recoverable quantities).

Many know that platinum wire will catalytically combine gas molecules but don’t bother to check out the details.

Basically gas molecules stick to the surface of the Platinum. Because of the distortion of their electron field and their close proximity. The combined molecule then breaks free.  So this is a catalytic (the Platinum remains unchanged)) process that depends on the surface area available.

By making the platinum into a thin coiled wire, you maximise the surface area available for the reaction.

Being in the form of a thin coiled wire has a secondary benefit in the following context.

The combination of Gas (i.e. the fuel) with Oxygen is exothermic, meaning that a thin coiled wire, having very low heat capacity, will quickly heat up to a temperature at which it will ignite the Gas from a Bunsen Burner. This was demonstrated to be very efficient by our Chemistry teacher, using a prepared wand.

I wonder why it’s not used on gas cookers, avoiding the need for push buttons and wiring. They would never fail unless damaged in some way and could be easily replaced by some sort of screw on spares.

An interesting, although not entirely relevant, footnote, here, is that I spent six month’s at Mullard’s Semiconductor Labs, where one of the sections in my department was making YIG and YAG crystals, using Platinum crucibles. These crucibles had to be hammered to get the crystals out and became badly misshapen. The point is that, as with Gold, the price of Platiunum rises and falls considerably, so by selling the mishapen crucibles, when the price was high, they could buy new crucibles at no cost.

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