172 



Note on Electrolytic Experiments. [Feb. 12,. 



copper, when the platinum plate and a thick platinum wire were used 

 as the two poles. Various modifications of these experiments may be 

 made by employing different metals. The intensity current used with 

 a saturated solution of nitrate of potash, has the power of engraving 

 on glass, as described by von Plante. 



The determination of the heat evolved from the Jablochkoff candle 

 in the annular calorimeter formerly described, amounted to about 

 6,000 gram-units per minute, or in other words, it is about |th of 

 the total radiation of the Siemens machine when the small resistance 

 of the electric arc is alone in the circuit. 



On introducing into this circuit containing a Jablochkolf candle the 

 voltameter which was formerly used, and in which no decomposition 

 was apparent when used alone, the total radiation of the candle 

 was very slightly diminished, but the cell showed intermittent bursts 

 of electrolytic gas just as when the tuning fork was used as formerly 

 described. This seemed to be always associated with any quality 

 of intermittence due to the want of regularity in the action of the 

 candle. Assuming that the whole work of the intermittent current 

 was exhausted first in electrolysis, and then in recombination of the 

 separated electrolytes, and that recombination resulted solely in a 

 heating effect localised in the cell, then the elevation of temperature 

 would be a measure of the chemical work done. As, however, the 

 amount of this heating is relatively small in comparison with the 

 current circulating, we must suppose that a considerable portion of 

 the energy of recombination is thrown into the circuit as a new electro- 

 motive force. The chief interest in these experiments is the value of the 

 de Meritens machine, as having many of the advantages from Plante's 

 secondary piles, and the facility and ease with which this power can 

 be used. Mr. Spottiswoode's recent experiments have shown that 

 the character of the arc obtained from the de Meritens machine is 

 intermediate in qualities between that of the ordinary arc and that of 

 the induction spark, and may be employed with great advantage in 

 exciting the induction coil. The use of it in spectroscopic work has 

 been fully detailed to the Society in conjoint communications with 

 Professor Liveing. The luminous discharge obtained below the 

 surface of fluids. shows another valuable use of the machine in con- 

 nexion with this subject. 



