﻿Dr. T. J. Baker o)i Breath Figures, 755 



Influence of the temperature of the flame, 



Aitken mentions that the flame of burning alcohol does not 

 produce satisfactory breath figures. The author made a 

 small spirit-lamp with a test-tube as reservoir and a tuft of 

 glass-wool supported in a glass tube as wick. This was 

 supplied with *' industrial spirit," and was regulated to give 

 a flame about ^ inch high. No breath figures could be 

 obtained, probably because such a small flame is not very 

 hot. It was found that the larger flame of an ordinary 

 spirit-lamp gave a breath figure, but the effect was distinctly 

 weak. 



Souie methylated ether was purified by standing over 

 caustic potash and potassium permanganate for several days 

 and then distilling. The portion coming over at 34°'5 was 

 collected and used in the lamp described above. No breath 

 figures were obtained. It may be noted that an ether flame 

 always leaves a small deposit of soot on the plate, and the 

 non-production of a breath figure in these circumstances 

 seems to negative Aitken's suggestion that dust is an im- 

 portant factor. 



If a mouth-blowpipe is used in conjunction with an alcohol 

 or with an ether flame good figures are easily obtained. 



Again, if a glass plate is drawn rapidly across the extreme 

 tip of a well-shaped blowpipe-flame, the breath figure shows 

 a perfectly uniform " black " track ; but if the plate cuts 

 across the flame near to the reducing cone, then the breath 

 figure shows two clear " black " lines which correspond with 

 the hot exterior of the flame, whilst the space between them 

 exhibits more or less of the white condensation corresponding 

 to the relatively cool interior of the flame. 



These facts seem to indicate that the condition of the 

 surface necessary for the production of these figures is only 

 attained after it has been exposed to a flame whose temperature 

 is above a certain minimum. 



Sir J. J. Thomson ('Conduction of Electricity through 

 Gases/ p. 194) says " ionized gas is produced by flames of 

 coal-gas whether luminous or not, by the oxy-hydrogen 

 flame, by the alcohol flame of a spirit-lamp, by a flame of 

 carbonic oxide : it is not, however, produced in very low 

 temperature flames such as the pale lambent flame of 

 ether." 



The parallelism between the ionizing effects, of the flames 

 mentioned in the foregoing abstract and the facts just stated 

 in connexion with the production of breath figures suggests 



3 C 2 



