large value resistors

[Ian Fritz]

Hi all --

One minor footnote to this discussion. Coleman stopped using the
radioactive mantles some time ago.

  Ian

"Mike I." wrote:
> 
> A geologist friend who was involved in uranium exploration in
> Saskatchewan in the 1980's quickly learned to store the Coleman lantern
> mantles well away from the ore assay shack. They made the
> scintillometers go wild... they contain thorium nitrate before ignition,
> thorium oxide after ignition. The oxide improves the luminous efficiency
> of the mantle in a similar manner to the way thorium activated tungsten
> cathodes in vacuum tubes put out more electrons at lower temperatures
> than simple tungsten filaments.