This section is from the book "Amateur Work Magazine Vol6". Also available from Amazon: Amateur Work.
The use of sodium for overhead transmission is attracting the attention of electricians. It is said to be cheap and a good conductor of electricity, but as its marked affinity with oxygen causes it to ignite when placed in contact with water, its employment in the form of a conductor would be limited, probably, to overhead transmission lines or feeders for railway work. The general process for constructing sodium conductors is to take standard wrought-iron pipes and heat them to a point well above the melting temperature of sodium. The sodium is then melted in special kettles and is run into the pipes, solidifying when cool. There is said to be no marked depreciation of either the sodium or the pipe if the latter be properly protected by a coat of weather-proof paint. For the same conductivity the price of the complete sodium conductor is much below that of copper cables, being in small sizes not more than 50 per cent, and in large sizes not more than 20 per cent, of the cost of copper. For instance, a half-inch wrought-iron pipe filled with sodium has a capacity of 19 amperes, and costs about 31/2 c. per ft., against 8 1/2 c. for a copper line of the same capacity. A 6-in. sodium conductor would carry 8.130 amperes, the cost of the line being about $1.40 per linear foot, as compared with $6.30 per foot for copper. These figures were estimated on the basis of 7 1/2 c. per lb, for sodium and 16c. per lb. for copper.