1921.] Marsden and Fenton.—Coal, Gas, and Electricity. 261 
Oven Cooking. 
Theoretical 
B.Tli.U. for Id. 
Efficiency. 
B.Th.U. in Oven 
for Id. 
Coal 
32,000 
Per Cent. 
4-7 
1,500 
Gas 
4,500 
35 
1,575 
Electricity . . 
2,280 
75 
1,700 
The figures for coal in the above table are for continuous oven cooking 
for a period of a few hours. Further, the figures take no account of the 
cost of the labour and cleaning involved in the use of the various fuels. 
Taking the latter into account, it must be concluded that, except where the 
coal-range is required for other purposes at the same time, it is more 
Fig. 1.—“Hot-point” electric oven. 
economical and easier to use electricity or gas, electricity being the cheapest 
at the rates quoted. Moreover, it is generally accepted that cooking by 
electricity causes less loss of weight by shrinkage of meat than is involved 
in the case of cooking by gas. 
Tests were made also on the cost of maintaining the interior of a gas 
or electric oven at the same temperature, and the results were as follows :— 
Temperature. 
Cost per Hour. 
Gas at 8s. 4d. 
Electricity at 1 Jd. 
d. 
d. 
355° F. = 180° C. 
0-90 
F08 
520° F. = 270° C. 
1-92 
F80 
18—Science. 
