Chemistry and Physics. 63 



tered in qualitative analysis rather than to explain the facts by 

 the theory. The main fact is that acids, bases, and salts readily 

 exchange their metals (including the hydrogen of acids) in solu- 

 tion, and a clear statement of this fact, devoid of theory, would 

 serve as a good introduction to the study of analytical chemis- 

 try. At the present time, since the ionic theory is now presented 

 in the text-books of elementary chemistry, there appears to be no 

 more need of an introduction of the ionic theory than for one on 

 the atomic theory in connection with qualitative analysis, for the 

 student should already have an inkling of both these theories. 

 These remarks on the use of the ionic theory in connection with 

 qualitative analysis are not directed as much toward the book 

 under consideration — for it is comparatively moderate in this 

 respect — as toward the recent tendency to carry the use of the 

 ionic theory to excess in such books. h. l. w. 



5. On Flames of Low Temperature supported by Ozone. — In 

 a paper read before the Physical Society of London on Nov. 25, 

 1910, it was shown that the yellow afterglow, often observed 

 when an electric discharge has passed through a vacuum tube 

 containing air, is due to the mutual reaction of nitric oxide and 

 ozone, each formed in the discharge. The glow can be imitated 

 by causing chemically prepared nitric oxide to mix with a stream 

 of oxygen which has been through a vacuum tube at low pressure. 



The investigation of this action of ozone has been extended by 

 R. J. Strutt to other oxidizable gases and vapors. The essential 

 parts of the apparatus used and the manner of experimenting 

 may be briefly described as follows : After being admitted to the 

 discharge tube at one end, oxygen passed through the tube and 

 was partially converted into ozone by the action of an electric 

 discharge which took place between electrodes placed in short, 

 auxiliary tubes sealed to the main tube at right angles. The dis- 

 charge tube was bent through 90° at a point a few centimeters 

 from its exit end, and this portion of the tube was surrounded 

 by a larger coaxial tube to which it was sealed near the bend. 

 The outer or jacket tube was straight, it extended beyond the 

 open end of the discharge tube, and it was terminated by a quartz 

 window. The gas, whose ability to react with ozone was to be 

 studied, entered the jacket tube at the end remote from the 

 quartz window, passed along this tube and met the ozone and 

 oxygen at the nozzle end of the inner or discharge tube. Then 

 all the gases were sucked out of the apparatus by a mechanical 

 pump which communicated with the jacket tube close to the 

 quartz window. Thus the seat of any reactions which took place 

 was in the region immediately surrounding the outlet of the 

 discharge tube. Since this opening was directly opposite the 

 quartz window it was a simple matter to focus on the slit of the 

 spectrograph any light which accompanied the reactions. Obvi- 

 ously, the object in bending the prolongation of the discharge 

 tube at right angles to the main axis of the region of discharge 

 was to prevent light from the discharge from reaching the slit of 



