286 REPORTS ON THE STATE OF SCIENCE, ETC. 



The ' radiant efficiency ' of a modern gas fire may be said to be about 50 per 

 cent, on the net calorific value of the gas burat therein ; moreover, experiments 

 made under Professor W. A. Bone's direction at South Kensington have proved 

 that, within wide limits, such radiant efficiency is independent of the chemical 

 composition and calorific value of the gas burnt, provided that the number 

 of calories by combustion developed per hour is kept suitably constant for 

 the particular size of fire. Gas fires are now available which are capable 

 of ventilating rooms quite as well as an open coal fire; and it may be taken 

 for granted that both these appliances are capable of providing a healthful 

 source of radiation for the warming of living rooms without unduly heating the 

 atmosphere thereof. With regard to electric radiators, whose radiant efficiency 

 may be as high as 75 per cent., while these are very portable and therefore 

 convenient for placing where the heat is required, they do not directly ventilate 

 an apartment. 



The recent determination by Dr. Margaret Fishenden, for the Manchester 

 Corporation Air Pollution Advisory Board, of the radiant efficiencies of coal, 

 coke, and semi-coke when burnt in open fire-places (Fuel Research Board Special 

 Report, No. 3) are of considerable interest. Her experiments have shown, not 

 only that such efficiency is much greater than has generally been supposed, but 

 also that there is not so much difference as might be thought between the 

 efficiencies of different grates. 



Working with a number of coal-fired open grates, including what were 

 supposed to be the best and the worst types, the radiant efficiency in all cases 

 was found to lie between 20 and 24 per cent, of the heat of combustion of the 

 coal actually burnt during each test. When dried coke was used as fuel, 

 radiant efficiencies up to 25 and even 28 per cent, were obtained; the values 

 were, however, materially diminished when wet coke was used. Tests made 

 with the low-temperature carbonisation ' semi-coke ' gave radiant efficiencies of 

 up to 33 per cent, in a grate which with ordinary coal gave 25 per cent. It 

 is also to be noted that the tests showed that, within tlie limits likely to be 

 encountered in practice, with domestic fire-grates the radiant efficiency was 

 found to be independent of the draught intensity, and also confirmed previous 

 experience that treatment of the fuel with preparations (consisting mostly of 

 common salt), which are sometimes advertised as doubling the value of a ton 

 of coal, had no appreciable effect upon its radiant efficiency. Altogether, then. 

 Dr. Fishenden's investigations may be said to have gone far to remove from 

 the open fire-place the stigma of gross inefficiency. 



The Fuel Research Board have also published some work by Dr. Fishenden 

 which deals with the efficiency of kitchen appliances (Fuel Research Board 

 Technical Paper No. 3 : ' The Efficiency of Low-temperature Coke in Domestic 

 Appliances '), and, in addition, one of the members of our Committee (Mr. A. H. 

 Barker) has also devoted considerable time to the difficult question of the 

 determination of the efficiency of domestic cooking appliances. A memorandum 

 by him on the subject is appended to this Report, the results of his experiments 

 having been published in detail bv the Fuel Research Board (Special Report 

 No. 4), 



Dr. Fishenden has concerned herself with the determination of the radiant 

 efficiencies of the ranges examined, as well as their efficiency in the production 

 of hot water, whereas I\Ir, Barker has concerned himself generally with the 

 question of the efficiency of ranges when functioning for the production of 

 hot water or for cooking. The latter Report also touches upon the question 

 of gas and electri: cookers, but the Committee does not propose to comment 

 upon this aspect of the case as it would r.ppear to require further investigation. 



Whilst perhaps it would be premature to express any final opinion as to the 

 precise significance of the results obtained, in view of the fact that the work 

 is from the experimental point of view in its infancy, and that rather marked 

 differences in efficiencies are cited in the two Reports, due probably to differences 

 in the type of range tested, the Committee desires to call attention to the 

 very great interest of the work at the present juncture, and to the desirability 

 of the inquiry being continued. 



The combination of several different functions, namely, of a fire-heated oven, 

 a fire-heated hotplate, a fire-heated boiler, and also a fire to warm the kitchen, 

 would appear to involve heavy fuel consumption, as compared with the fuel 



I 



