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Radio Record, Volume VII, Issue 46, 24 May 1935, Page 45

If a.small quantity of commion soda is powdered and mixed with .an equal quantity of finely-crushed coal ash, and the mixture formed into a thitk paste with a little water, it will be found that enamel ‘insulation on wire can bé removed: by rubbing between the fingers or by applying with. a rag. Switch contacts are particularly: liable to give rise to faults because the springiness on which: their action depends can easily be impaired by long or careless use. ‘ '