vi. Proceedings. [Ja?i7iary yth, 191 9. 



The experiments included determinations of: 



(i) The "radiant efficiency," or the percentage of the 

 total calorific value of the coal burned, which 

 entered the room as radiation. 



(2) The distribution of radiation. 



(3) The volume of air passing through the room. 



(4) The amount of heat passing away above the ceiling 

 level in the hot flue gases.- 



(5) The heating of the room air. 



Three different grates gave radiant eft'ciencies of 21, 24I, 

 240/0 respectively; the radiant efficiency was not dependent 

 upon the draught, even over such wide limits as from one 

 to nine changes of air per hour. The maximum intensity 

 of radiation was found (upwards) at an angle of about 60° 

 to the horizontal through the centre of the fire. ; 



The amount of heat contained in the hot flue gases 

 passing up the flue above the ceiling varied from about 

 550/0 of the total calorific value of the fuel burned for 

 draughts of about 20,000 cubic feet per hour (nine changes), 

 to about 150/0 for one change per hour. The heat used in 

 warming the room air was very small, generally below 10 0/0. 



Certain advertised preparations, solutions of which were 

 claimed when previously sprayed upon the coal, greatly 'to 

 increase the efficiency of fires, had been analysed and found 

 to consist chiefly of common salt. Their use was found to 

 have no effect whatever either upon the radiant efficiency, 

 th<i duration of burning, or the rise of air temperature 

 produced by coal fires. 



Ordinary Meeting, January yth, 1919. 



The President, Mr. William Thomson, F.R.S.E., F.I.C., F.C.S., 

 in the Chair. 



Joule Centenary Meeting. 



(Dr. James Prescott Joule was born in Salford on the 24th of 

 December, 18 18.) 



Professor Sir Ernkst Rutherford, M.A., D.Sc, F.R.S., 

 gave an account of " The Work and Influence of Joule." 



At the outset, the lecturer stated that the .Society had 

 hoped to secure on this occasion an address from a distinguislied 

 member of the Society who had known Joule well, personally. 

 Unfortunately, this had not proved possible, and he had been 

 asked at very short notice to fill the gap. In the short time 



