RECENT PROGRESS IN PHYSICS. 413 



with a point, an electroscope was placed ; as soon as the machine 

 was turned the leaves diverged, and this divergence remained when 

 the conductor was discharged ; in spite of this continued divergence, 

 the electroscopo had no permanent cliarge, hut the leaves diverged in 

 consequence of the inductive action of the air electrified by the point, 

 which air cannot lose electricity by the discharge of the conductor. 

 Van Bees showed that the electroscope actually had no permanent 

 charge by the collapse of the pendulum when he took the electroscope 

 to an adjoining room, and by its diverging again when he placed the 

 instrument in its former position. By continued turning of the ma- 

 chine, the particles of air electrified at the point were scattered, they, 

 in part, reached the electroscope, and thus communicated to it a per- 

 manent charge. 



No objection can be urged against this. 



Van Bees now applies these views of the action of points to the action 

 of flame ; air, ascending from flame, is charged by it and can then act 

 inductively on neighboring conductors. When the electroscope h, 

 in th« first experiment of Biess, mentioned on page 410, ap- 

 peared to be permanently electrified, according to Van Bees, this was 

 only a consequence of the inductive action of the electrified air above 

 the flame, which air, on discharging the plate A, cannot be itself 

 discharged because it is an insulator. The inductive action which 

 proceeds from flame, Fan Bees considers much too feeble to effect so 

 great an accumulation of attracted electricity in the plate of an elec- 

 troscope brought near to it (the plate B in Biess' experiment) as to 

 cause a current in consequence of which the electroscope should remain 

 charged. On this point it is evident that no general rule canbe given, 

 since so much depends upon special relations, such as the dimensions 

 of the plates, the dimensions of the inducing body, the relative dis- 

 tances, &c. 



The difference between the views of the two physicists is essentially 

 as follows : According to Biess, the ascending conducting rnass of 

 steam, going off" in single threads, acts inductively upon the neighbor- 

 ing conductors ; on the other hand, according to Van Bees, the induc- 

 tive action proceeds from the non-conducting mass of air above the 

 flame, to which the electricity is communicated by the conducting 

 flame. 



The truth may lie between these two views. It is beyond doubt 

 that a conducting column of steam forms over flame, and it is highly 

 probable that it is diffused in fine conducting threads. If this mass 

 of steam, with its points, is electrical, it must act inductively on the 

 neighboring conductors, according to the view of Biess. But how far 

 the column of steam continues to be a conductor is uncertain. Most 

 of the gases and vapors formed by ignition lose their _ conducting 

 power by cooling ; but they will retain the electricity imparted by 

 flame, and thus an electrified non-conducting mass of gas forms above 

 the electrified flame and its conducting parts, which gas also acts in- 

 ductively on neighboring conductors, in accordance with the view of 

 Van Bees. 



It is very evident that, in powerful excitation of electricity, the 

 transfer of electrified air and particles of dust is added to the above- 



