Properties of High Temperature Flames. 811 



Conclusions. 



Only very small differences between the two rates of: leak 

 were obtained, and these lay within the limits within which 

 two tests carried out under precisely the same conditions 

 could be made to fall. 



This showed that no ionizing rays capable of penetrating 

 a thin sheet o£ tinfoil, after traversing the small distance in 

 air between the arc and the cover, necessary on account of 

 the great heating effect, were given off from the arc. 



The Oxy-Coal-gas Blowpipe. 



The general arrangement of the apparatus used in this 

 case was exactly the same as in the previous one, except that 

 a cowl of tin plate was fitted to the bottom of the chimney 

 to adapt it for use with the long narrow blowpipe flame. 



An ordinary injector blowpipe was used coupled to the 

 gas-mains and an oxygen cylinder. This was held in a 

 clamp above the outer case of the electroscope, the distance 

 between the flame and the cover being 5 cm. 



As in the last case, tests were run with blank test following 

 an exposed one and vice versa, the procedure throughout 

 beino- the same. 



© 



The Oxy acetylene Blowpipe. 



The same arangement was again used. The same blow- 

 pipe was used and fed with acetylene from a GO cub. ft. 

 cylinder of dissolved acetylene supplied by the Acetylene 

 Illuminating Co. 



A non-return water-valve included was in the circuit as a 

 safety device, but it was chiefly used as a manometer for 

 regulating the acetylene supply. Some trouble was ex- 

 perienced through the popping back of the flame due to 

 overheating of the blowpipe, but this was overcome by 

 cooling the nozzle by means of strips of copper-foil dipping 

 into a dish of cold water, which was frequently refilled. 



The distance between the flame and the cover was again 

 about 5 cm. 



At first a good deal of trouble was experienced in getting 

 regular readings, but this was overcome by paying special 

 attention to the temperature regulation. The same procedure 

 as in the previous tests was adopted. 



Examples of curves and readings obtained from the two 

 blowpipes are given below (Table II. and fig., 3) . 



