COAL AND ELECTRICITY.

New Zealand Herald, Volume LXIII, Issue 19215, 2 January 1926, Page 2 (Supplement)

COAL AND ELECTRICITY.

Among the many schemes for using coal to the best advantage is one devised by Dr. Wall of Sheffield University, who hopes to turn coal directly into electricity. His invention is bs.sed on the old idea of what is called the thermo-electric "couple." StripE of any .two different metals,, if fastened together at one end, will produce an electric current if tho joiut is heated. Bismuth and antimony are specially good in this respect, so much so that neat couples of these metals are actually ~used to measure temperatures. The current they produce is very small, so that a large number are usually placed together, ana the instrument is called a thermopile. Large thermopiles have been made for years for producing just enough electricity to charge a small storage battery; they are heated by a number of gas flames, and in this way the heat of tho gas is turned directly into current.

Hundreds of such thermo-cocples could be packed together and heated by a coal fire so as "to generate electricity without, the use of steam-engines and dynamos. If Dr. Wall's invention (in which he uses a new alloy) can to made a success it will be of the greatest, value at a time when oil fuel is fighting for supremacy with coal.