Experiments on various Liquids. 167 



Ethyl oxide (purus, P.B.), tried as a conductor with machine 

 and Leyden jar, gave a good restoration with eight turns of 

 the plate, pretty strong with ten turns : and the effect was 

 strengthened by compression parallel to lines of force, and 

 regularly neutralized by tension. With the Euhmkorff 's coil 

 afterwards, there was a good effect obtained even when the 

 length of the safety spark was reduced to zero ; and the action 

 of the compensator was as clear as formerly, extinction by the 

 proper tension being regularly perfect. This liquid is there- 

 fore purely negative, and a great deal stronger than ethyl 

 alcohol. 



Amyl oxide, tested for insulation in the plate cell, gave a 

 strong spark (f inch) from the prime conductor. Tried op- 

 tically as a nonconductor, it acted like the best of the fixed 

 oils. As soon as the machine was set in motion, there was a 

 strong effect from extinction, which was neutralized perfectly 

 by tension parallel to lines of force. Among chemically 

 definite bodies, I regard this amylic ether as the best negative 

 dielectric yet discovered. 



Iodides, C„H 2re +iL 



10. Four of these were examined in the plate cell, first as 

 nonconductors, but without effect, then as conductors. The 

 regular effects were disturbed in some degree by photogyric 

 action, but were all clearly positive. 



Methyl iodide, without the jar, gave a good restoration, 

 which was too quick to be characterized. With the jar and 

 five or four turns of the plate, the effect was distinctly positive, 

 strengthened by tension parallel to lines of force, but not sen- 

 sibly affected by compression. 



Ethyl iodide was of a deep red colour, much darker than the 

 methyl compound, but otherwise not distinguishable from it 

 in experiment. 



Butyl iodide, still deeper in colour, and almost opaque, 

 required the jar and fifteen or more turns of the plate. The 

 effect was regularly strengthened by tension parallel to lines 

 of force, but not sensibly affected by compression. 



Amyl iodide was the strongest of' the four. With the jar 

 and three or even two tarns of the plate, it gave a clear effect, 

 which was strengthened by tension parallel to lines of force, 

 and weakened to extinction by compression. 



Bromides, CJIga+iBr. 



11. These are purely positive, the powers rising as n increases; 

 and they are distinctly stronger than the corresponding iodides. 



Ethyl bromide, tried as a conductor with the jar, gave a clear 



