ON FUEL ECONOMY. 285 



burnt under boilers, and a large electric power-station scheme at Morwell is 

 rapidly materialising, and a large order for water-tube boilers in connection 

 therewith has recently been placed in this country. 



The problem of how such low-grade fuel as brown coals and lignites can 

 be most efficiently burnt in boilers has therefore become one of great importance. 

 It is obvious that a prime condition of efficient combustion is that coal shall 

 be dried before being burnt; and as this drying can be effected at the expense 

 of some of the sensible heat in the waste gases from the boiler, provided that 

 they contain not less than 10 per cent, of carbon dioxide, such a drying operation 

 may be cheaply carried out as .an integral part of the boiler operation. Whether 

 or not, as an addition to such drying operation, the coal should be subjected 

 to a preliminary low-temperature carbonisation, using the residue therefrom as 

 the boiler fuel, is a matter for future investigation to decide. In this connection 

 attention may be drawn to the recent discovery made by Bone (Proc. Roy. 

 Soc, A, vol. 99, 1921) whilst investigating Morwell brown coal, Saskatchewan 

 and other typical lignites : — 



[a) that there is for each particular brown coal or lignite a certain definite 

 temperature limit (usually between 300° C. and 400° C.) up to which 

 it may be heated (in the dry state) so as to effect a considerable 

 chemical condensation in its cellulosic or humic constituents, with 

 simultaneous expulsion therefrom of steam and carbon dioxide, 

 together with a small but variable proportion of carbonic oxide ; and 

 that such chemical condensation is unaccompanied by any other change 

 productive of either hydrogen or hydrocarbons ; 



(6) that, by means of such condensation, substantially the whole of the 

 potential energy of the fuel may be correspondingly concentrated by 

 suitable heat treatment (within the prescribed temperature limit) in 

 the resulting carbonaceous residue, which may therefore be burnt with 

 greater calorific intensity than the original coal; and 



(c) that, accordingly, such treatment constitutes a possible means of ' up- 

 grading ' brown coals and lignites generally, thus improving their fuel 

 values. 



V. Domestic Heating and Cooking Appliances. 



A good deal of valuable investigation work has recently been done by 

 persons not actually engaged in the industries concerned in the direction of 

 testing the efficiencies of domestic heating and cooking appliances, with results 

 of considerable interest in connection with the important auestion of fuel 

 economy in our homes, where are burnt not only some 40 million tons of coal 

 per annum, but also the bulk of the gas and some of the coke sent cut from 

 the country's gasworks. 



In the first place, physiological research has emphasised the intimate con- 

 nection, from the point of view of health and comfort, between the coenate 

 problems of heating and ventilation in regard to domestic apartments. More- 

 over, the introduction of the Kata-thermometer has placed at our disposal a new 

 method for estimating the ' cooling power' of the air, which has been shown to 

 be a governing factor in regard to what may be termed ' comfort conditions ' 

 in living rooms. Also, the physiological value of radiation from a red-hot 

 incandescent surface, as distinct from convected heat, has become to be more 

 clearly recognised than ever before. Indeed it may be said that the more nearly 

 the conditions under which our living rooms are warmed and ventilated approach 

 those of a warm summer's day — a cooling breeze blowing round the head, the 

 varvin"' sinishine warming one side of the bodv. and the warm ground for the 

 feet — the more comfortable and healthful will they be. The desirability of such 

 conditions, which may be contrasted with the warm air of rooms heated by 

 convection from steam coils, probably explains the Englishman's decided 

 preference for the radiation from an open fireplace durinsr our dreary British 

 winters over tlie various forms of central heating which are favoured in America 

 and other countries where the winters are c^older but brighter. Therefore, 

 having reg;ird to the character of British winters, the estimation of the ' radiant 

 pfficiencies ' of domestic fires is of predominant importance. 



