210 Mr. G. A. Hemsalech : A Comparative Study 



spectroscopic appliances (Dr. King used a high- dispersion 

 grating spectrograph, whereas our observations were made 

 with an ordinary prism apparatus) presents some diffi- 

 culty, inasmuch as a high dispersion will bring out a 

 greater number of lines than a low dispersion, especially in 

 the presence of a continuous spectrum. As a result o£ his 

 comparison Dr. King has arranged the several flames used 

 by Dr. de Watteville and myself in the following order with 

 regard to their effective temperatures in producing radiations 

 from iron vapour, as compared with the furnace : — 



Effective Temperature Actual Flame 



as derived by Temperature 



Flame. Dr. King. (Dr. Bauer). 



Air-coal gas (mantle). below 1800° C. 1850° C. 



Oxy-hydrogen. about 1800 „ 25.50 „ 



Oxy-coal gas. about 2000-2100 „ 2450 „ 



Oxy-acetylene. about 2000-2100 „ 2700 „ 



Air-coal gas (cone). about 2200 „ <1700 „ 



I have added to Dr. King's values those found by Dr. Bauer 

 for the same flames by direct determinations*. Now it is of 

 importance to mention here that Dr. Bauer used the same 

 methods of colouring the flames as were devised and applied 

 to their spectroscopic examination by Dr. de Watteville and 

 myself. Moreover, in his final experiments on the high- 

 temperature flames, namely the oxy-coal gas, oxy-hydrogen 

 and oxy-acetylene flames, Dr. Bauer made use of our burners 

 and, working for the time being in our laboratory, availed 

 himself of our original equipment for the application of the 

 spark method. Also I had the honour of assisting him in 

 producing these high-temperature flames, and I am therefore 

 in a position to state definitely that the flame conditions 

 under which Dr. Bauer carried out his temperature determi- 

 nations were identical with those used by Dr. de Watteville 

 and myself in our spectroscopic researches on the same flames. 

 But when we compare the results obtained by Dr. Bauer 

 with those derived by Dr. King, we find discrepancies which 

 appear to be very much in excess of any experimental errors 

 that could reasonably be expected to affect Dr. Bauer's 

 figures. With regard to the air-coal gas cone I have already 

 shownf in two previous communications that the line emission 

 is not due to temperature, but to chemical action. It is 

 indeed inconceivable that the temperature of the cone film 



* E. Bauer, Theses de Doctoral, Paris, 1913. 



t Hemsalech, Phil. Mag. vol. xxxiii. p. 1 (1917) — I. ; ibid. vol. xxxiv. 

 p. 221 (1917)— II. 



