Prof. E. Edlund on Unipolar Induction. 289 



tion of permanganate. The action is not instantaneous, as in 

 the case of the binoxide of nitrogen, but is comparatively slow. 



118 cubic centims. of CO and 30 cubic centims. of the 

 above solution of potash and permanganate of potash were 

 sealed up and heated in the water-bath, being frequently 

 taken out of the bath, cooled, and shaken. Altogether the 

 heating occupied some three or four hours. On opening the 

 tube under water it was found that great absorption of gas 

 had taken place. 



Of the 118 cubic centims. of CO taken for experiment, 



92 cubic centims. were absorbed, 

 26 „ „ residue. 



118 



The action appears to be 



CO + = C0 2 , 



regard being had to the amount of KMn0 4 which had been 

 reduced during the operation. At ordinary temperatures the 

 action takes place, but very slowly. 



Hydrogen 

 is also absorbed by the alkaline solution of permanganate. In 

 an experiment in which 64 cubic centims. of hydrogen were 

 sealed up with 16 cubic centims. of alkaline permanganate and 

 heated for some hours in the water-bath, an absorption of 34 

 cubic centims. of hydrogen was noted. 

 We are continuing the investigation. 



XL. Researches on Unipolar Induction, Atmospheric Electri- 

 city, and the Aurora Borealis. By E. Edlund, Professor 

 of Physics at the Swedish Royal Academy of Sciences*. 



[Plate VIII.] 



" Res ardua rebus vetustis novitatem dare, novis auctoritatem, obseuris 

 lucem, dubris fidein, omnibus vero naturam et natures suae omnia." — 

 Pliny, Hist. Nat. t. i., praefatio. 



§ 1. Unipolar Induction. 



WE represent to ourselves a steel magnet in a vertical 

 position, readily set in rotation about its geometric 

 axis; and we picture it besides surrounded by a metallic muff 

 in the form of a cylinder, which can likewise turn about the 

 same axis. If the current of a pile be caused to pass into this 



* Translated from a copy, communicated by the Author, of the Kongl, 

 Svenska Vetenkaps-Akademiens Handlingar, vol. xvi. No. 1. 



Phil. Mag. S. 5. Vol. 6. No. 37. Oct. 1878. U 



