in Magnetism and Electricity. 107 



192. The principal electromotor used in these experiments 

 was the 10-inch intensity-armature, the currents from which 

 were turned all in the same direction by means of a commutator. 

 The current from this armature, as I have already said, would 

 melt in short circuit 7 feet of iron wire '065 of an inch in 

 diameter. 



193. About 300 feet of naked copper rope, T, fig. 16, such 

 as was used in the previous experiments (103), were extended 

 in the canal in a single length, and connected with the aeriai 

 conductor I, for the purpose of obtaining a good discharge from 

 the pole F of the machine. 



194. The other aerial conductor, H, connected with the pole 

 G, instead of terminating in the canal in the same manner as 

 the conductor I, terminated in a pool of fresh water, U, formed 

 in the ground about 200 feet from the canal. This pool was 

 about 30 inches in diameter and 10 inches deep. 



195. A thin deal box, V, 1 foot square and 8 inches deep (into 

 the construction of which no metal was allowed to enter), was 

 fitted up as a pneumatic trough for the purpose of collecting the 

 electrolytic products in tubes or jars. This trough was floated 

 in the pool and then filled with fresh water. 



1 96. The free extremity of the aerial conductor H was termi- 

 nated with a piece of thick copper wire well insulated with gutta 

 percha, and the end of this copper wire was again terminated 

 with a strip of platinum 3^ inches long and \ an inch wide. The 

 strip of platinum was introduced into the open end of a eudio- 

 meter-tube 18 inches long and \ an inch internal diameter, 

 graduated on its outer surface into hundredths of a cubic inch. 



197. When contact was made between the poles of the elec- 

 tromotor and the arrangement of conductors above described, so 

 long as the platinum termination of the aerial conductor H was 

 not allowed to touch the earth or the water in the pool, no indi- 

 cation of the passage of a current appeared on the galvanometer 

 at N, nor in any other manner. But directly the platinum elec- 

 trode touched the water, either in the pool or in the pneumatic 

 trough, the galvanometer indicated the passage of a current 

 into the earth, while a stream of small bubbles of gas rose 

 from the electrode to the upper end of the inverted eudiometer- 

 tube, which had been previously filled with water. These bubbles 

 of gas, when collected in sufficient quantity, were examined and 

 found to be hydrogen. 



198. On reversing the polar connexions at the machine, so 

 that the platinum termination of the conductor H formed a posi- 

 tive instead of a negative electrode, the gas which collected at 

 the top of the eudiometer-tube was now found to be oxygen. 



199. A few measures of sulphuric acid were now mixed with 



