256 Dr. J. Kerr's Electro-ojrtic 



Chloroform, C H Cl 3 , is purely negative and pretty strong. 

 As a nonconductor, it gave a fine and purely negative resto- 

 ration from extinction. As a conductor, with increasing 

 charges, it gave a set of increasingly brilliant effects, always 

 purely negative, extinguished perfectly by tension parallel to 

 lines of force. With strong discharges, there was a fine exhi- 

 bition of extinction-bands, narrow and strong, brought in by 

 tension parallel to lines of force. 



Bromqform, as was expected, is also purely negative, but 

 weaker than chloroform. As a conductor, with the jar, it 

 gave a clear effect with 5 turns, strong with 10 or more turns, 

 and always purely negative. 



Acetyl chloride, C 2 H 3 OC1, is purely negative. As a con- 

 ductor, with strong charges of the jar, it gave an effect from 

 extinction which was merely strong enough to be characterized 

 as certainly negative, being strengthened by compression, 

 and weakened by tension. With the coil afterwards, there 

 was a certain disturbance produced in the liquid by each dis- 

 charge ; but the regular effect was clearer and stronger than 

 formerly, and always negative by both tests. 



Chloral, C 2 Cl 3 OH, is positive. As a conductor, with the 

 jar, it gave a good restoration with 10 or more turns of the 

 plate. The effect was regularly strengthened by tension, but 

 not sensibly affected by compression. 



Chlorjncrin, CC1 3 N0 2 , is purely negative. Tried as the 

 last, it gave a clear effect with 5 turns, strong with 10 or more 

 turns ; and the restored light was always strengthened by 

 compression, and always extinguished by the proper tension. 



26. Carbon tetrachloride is purely positive, like the dichloride 

 (formerly examined), but much weaker. Tested for insulation, 

 it gave a good spark (| inch) from the prime conductor. 

 The optical effect was not proportionably strong, not visible 

 indeed from pure extinction ; but with the assistance of the 

 hand-compensator it was brought out very clearly, and was 

 found to be purely positive. There was no advantage obtained 

 by trial of the liquid as a conductor, with or without the 

 jar. 



Sulphur chloride is purely positive. As a conductor, with 

 strong changes of the jar, it gave a faint but good effect, 

 which was strengthened by tension, and clearly weakened by 

 compression. 



Plwsphorus trichloride is purely negative, and stronger 

 than the last. As a conductor, with small charges of the jar, 

 it gave a moderately strong restoration from extinction ; and 

 the effect was regularly strengthened by compression, and 

 extinguished by tension. 



