364 On the Intensity and Quantily of Electric Cwrents. 



duced into both circuits. By suitable arrangements the hydro- 

 electric current may electrolyse a large quantity of water in a 

 given time, whereas the thenno-electric current will not evolve a 

 single bubble of gas, however long the action be continued. 



Perfectly similar phjenomena may be observed on comparing 

 two hydro-electric currents, one of which arises from a batteiy 

 of a great many small elements, the other from a batteiy of only 

 a few large cells. The electro-magnetic and the electro-chemical 

 effect of both may be exactly the same, or even the latter may 

 prove to be the stronger when thus tested ; and yet on submit- 

 ting the human body to the former current it may experience a 

 powerful shock, whereas on submitting it to the latter one there 

 will not be the slightest perception of pain. 



Puzzled by these contradictory results, electricians had recourse 

 to the hypothesis of two distinct qualities, which they assumed 

 to belong to eveiy current, namely intensity and quantity. They 

 admitted that the electro-magnetic and the electro- chemical 

 action of the current gave the measure of the so-called quantity 

 of electricity, and the amount of specific power to overcome any 

 obstacle brought into its path (in the above-mentioned experi* 

 ments, the additional length of wire, the voltameter or the human 

 body) was designated by the term intensity. Thus it was 

 believed that two currents of equal quantity might possess dif- 

 ferent degrees of intensity, and the reverse ; just as two rays of 

 light of the same colour may differ in their intensity. mi 



By arbitrarily assuming in each particular case that the two 

 qualities of the current were blended together in different pro- 

 portions, it was easy to explain the differences which were 

 observed when different currents were examined in the same cir- 

 cumstances, or the same current in different circumstances. The 

 greatest intensity, and, in proportion to it, the least quantity, 

 were generally ascribed to the currents of the electrical machine 

 andof Zamboni's pile. On the other hand, the least intensity, and, 

 in proportion to it, the greatest quantity, were ascribed to thermo- 

 electric currents. In the hydro-electric and magneto-electric 

 currents the quantity of electiicity was said to increase with the 

 size of the elements of the battery, or with the thickness of the 

 wire of the coils; its intensity, on the contrary, was said to 

 increase with the number of the elements put into «cfcM>ii,'Or 

 with the number of the windings of the coil of wire, rcjjza (jiD 



It need hardly be observed, that in the above-mentioned 

 experiments the thermo-electric current and the current produced 

 by the battery, consisting of a few large cells, play the part of 

 currents possessing little intensity and great quantity; whilst 

 the current of a battery of a great many small elements is sup- 

 posed to be endowed with great intensity and little quantity. 



