concerned in the Phcenomena of ordinary Electiicity, ^c. 213 



electric machine poured torrents of electricity into its coil by 

 direct communication, is beyond my comprehension, unless, as 

 I have already suggested, frictional electricity contains the mi- 

 nimum and voltaic the maximum of the effective elementary 

 constituent which produces these deflections. 



The next experiment was with nitric acid and potash ; but in 

 this case, nitric acid being a better conductor, it was not neces- 

 sary to place a plate of platinum in the bottom. A glass capsule 

 containing commercial nitric acid was connected with one bind- 

 ing-screw of the galvanometer by means of a platinum wire. 

 Another platinum wire, proceeding from the other binding-screw, 

 was well-connected with one end of a stick of caustic potash. 

 When the potash was sufficiently moistened by the atmosphere, 

 its other end was made to touch the surface of the nitric acid : 

 the needle instantly started 130° westward. The same wire de- 

 tached from the stick of potash and washed, when dipped in the 

 acid, only produced a deflection of 2°, and even that was east- 

 ward. Even dilute nitric acid produced considerable deflection 

 with potash. 



A strong solution of caustic potash touched by a platinum wire, 

 caiTying on its end a bit of platinum foil dipped in sulphuric 

 acid, caused a deflection of 10°. 



I fused some caustic potash in a capsule of virgin silver con- 

 nected with one of the binding-screws of the galvanometer : from 

 the other binding-screw proceeded a silver wire tipped with about 

 a quarter of a grain of sulphur melted on it. The fused potash 

 being touched with the sulphur, a very curious process of com- 

 bination took place, and the needle whirled round four times 

 with gi'cat velocity. On trying a new silver wire without any 

 sulphm', and touching the surface of the fused potash with it, 

 there was not the slightest effect on the needle. 



By means of the instrument called the Russian fui-nace, I 

 heated one end of a strip of sheet coppei' bright red-hot, its other 

 end being connected with one of the binding- screws of the gal- 

 vanometer. A copper wire proceeding from the other binding- 

 screw had a copper knob on its end, on which was fused a blob 

 of sulphur; on applying the sulphur to the white-hot copper 

 strip, the needle whirled round twice. To prove that this was 

 not the effect of thermo-electricity, I connected the ends of two 

 copper wires with the binding-screws of the galvanometer, one 

 with each, and brought their other ends into contact by a slight 

 twist. The flame of a spirit-lamp was applied to the twisted 

 junction of the wires : when red-hot there was thermo-electric 

 deflection ; but this at length ceased, and the needle returned 

 to the meridian. The lamp Jjcing still retained in its place, a 

 drop of burning sulphur was let fall on the junction, when a 



