.Experiments on various Liquids. 251 



Valerates, C 5 H 9 (C„H 2w+ i)0 2 . 



18. These are clearly positive, acting better than the acetates, 

 but not so well as the butyrates. 



Methyl valerate, with strong charges of the jar, gave a faint 

 effect which was distinctly positive, strengthened by tension, 

 and weakened by compression. The effect was very impure, 

 the flame being much deformed. 



Ethyl valerate was much stronger, and its action was almost 

 perfectly pure. As a nonconductor, it gave a clear, but very 

 faint, restoration from extinction. As a conductor, with in- 

 creasing charges, it gave a series of fine effects, all purely 

 positive, strengthened by tension, and extinguished by com- 

 pression. 



Amyl valerate, a much stronger photogyre than either of 

 the other two, acted only as a conductor, and required the jar. 

 The regular effect, not strong in any case, was always purely 

 positive by both tests. 



Benzoates, C 7 H 5 (C ;l H 2 «+i)Oo. 



19. These are purely positive, and about as strong as the 

 butyrates. 



Methyl benzoate acted clearly as a conductor ; but the effect 

 without the jar was too abrupt to be characterized. With 

 small charges of the jar the effect was positive by one test, 

 strengthened by tension, and either weakened or not sensibly 

 affected by compression. 



Ethyl benzoate, as a nonconductor, gave a faint but very good 

 restoration, which was purely positive. Tried then as a con- 

 ductor, with and without the jar, it gave an intense and very 

 slow effect, always purely positive by both tests. 



Amyl benzoate, not a clean sample, acted only as a conduc- 

 tor. With moderate charges of the jar, it gave an intense and 

 slow effect which was always purely positive, the extinction- 

 bands being brought in very finely by compression parallel to 

 lines of force. 



Nitrates, G^H^+jNOg. 



20. These are weak insulators in comparison with most of 

 the preceding ethers : they are clearly but not very purely 

 positive. 



Ethyl nitrate as a conductor, without the jar, gave a resto- 

 ration which was distinct, but very faint and abrupt. With 

 moderate charges of the jar, the effect was seen to be positive, 

 strengthened by tension, but not affected by compression. 

 With strong charges the effect was still very abrupt, neither 

 pure nor very strong, but certainly positive, 



