352 Experiments with Thermo- and Hydro-Electrical Currents, 



to me sufficient to establish the fact of electrolysis being performed by 

 currents of the lowest intensity* 



15. The annexed figure 4, shews the form of voltameter suited for ex- 

 cluding the atmosphere, or for working under pressure. 



Fig. A. 

 U 



a, a, A piece of glass thermometer-tube of round bore, blown into a 

 bulb at h, c. d, A small capillary tube drawn out from the bulb, and 

 hermetically sealed, after it has been used to fill the bulb with the fluid 

 under trial, e, e, Poles cemented or fused into the glass tube at a, a. 



With silver poles, I have found to fuse the glass round the silver the 

 most convenient, but with oxydizable metals[a cement must be employed, 

 for the pole would be coated with oxide of the metal, if fusing was at- 

 tempted. 



16. The decompositions performed by a single thermo-couple, acting 

 for a long time, can be effected quickly, comparatively speaking, by the 

 arrangement figure 1, exposed to the sky. At the beginning of May, a 

 single day of clear sun made a distinct deposit of silver on the negative 

 pole, in a voltameter, fig. 4, with silver poles, and filled with cyanuret 

 of silver. In this experiment, the decomposing cell is exposed to the 

 sun's rays to raise its temperature, and thus exalt the affinity which acts 

 in conjunction with the electrical force (10.). Again, with copper poles 

 in acidulated water, arranged similar to the foregoing experiment with 

 silver poles, the astral radiation, for 8 hours of a clear summer night, 

 temperature 60°, developes a therm o- electrical current which coats with 

 a thin film of the black oxide of copper the positive pole, while the ne- 

 gative pole retains its original brightness. 



17. The thermo-electric battery, fig. 1, arranged as described (7.), had 

 a voltameter, fig. 4, with a solution of cyanuret of silver, and silver poles, 

 attached by a pair of wires 40 feet long each ; these wires allowed the 

 voltameter to be maintained at a nearly uniform temperature of 90° in a 

 sand-bath ; the experiment commenced on the 1st of March and con- 

 tinued for two months ; the silver poles were adjusted at the beginning 

 to be exactly of the same weight ; when weighed at the conclusion, there 

 v/as a difference of ^Vth of a grain, with a distinct appearance of silver 

 deposited on the pole attached to the antimony extremity of the thermo- 

 battery, which is the negative pole for the current derived from astral 

 radiation. How the electrical current from this source should exceed 

 the quantity supplied by solar radiation during March and April, has 

 been to me a matter of some surprise, and even for May the nocturnal 



