Mr R. Adie's Experhnents with Electrical Currents. 347 



it is sought to increase the quantity of electricity from a single battery 

 to its highest point, this will be found to be attained by 11 pairs of bars, 

 where the electricity circulates through 176 inches, or nearly the same 

 length of the combined metals as in a battery of 90 pairs of 1-incli bars ; 

 hence, in constructing thermo-electrical batteries, the number of bars 

 capable of producing the greatest effect, is dependent on the length of 

 the bars chosen. Again, when we desire to produce the greatest effect 

 from a number of bars, whether in a single battery, or arranged in 

 several batteries acting together, the principle given by Professor 

 Daniell for arranging hydro-electrical cells, will hold good for thermo- 

 electricity.* *' From these experiments it appears, that the most ad- 

 vantageous adjustment of active force and resistance is in the series of 

 10 single cells, and that the largest amount of work which can be derived 

 from 20 cells, is when they are arranged in two series of 10." 20 pairs 

 of antimony and bismuth bars, 8 inches long, to give the largest amount 

 of work, should be disposed in two series of 10 each. 



On combining a number of series of thermo-electrical batteries to- 

 gether, the quantity of electricity supplied by the whole is a simple 

 multiple of the number ; I have found in 36 series with 80 inches circuit 

 for the electricity, the quantity to increase regularly with each succes- 

 sive addition of a series to those already in action. The case here is 

 different from bars combined to form a single battery; in the latter the 

 wliole electricity generated has to circulate through a greater length of 

 metal on each addition of a pair of bars, while the resistance to the con- 

 duction of the fluid progresses by this change in a greater ratio than the 

 quantity gained by each successive addition to the number of elements/ 

 In the former, where different series of thermo-electric batteries are 

 placed so as to act alongside one another, the length of the bars of 

 metal, through which the electricity passes, remains constant ; hence 2 

 series supply twice the quantity of one, 3 series three times the quantity 

 of electricity, and so on. 



When a pair of antimony and bismuth bars soldered together iiad 

 their joint, and a portion of the bars for about 2 Inches within It heated 

 by the sun, the electrical current generated was found to be more power- 

 ful than when the joint only was exposed to tlie solar rays ; this led me 

 to try arrangements of bars with pieces projecting beyond their joints, 

 antimony being a better conductor of heat than bismuth, was selected, 

 and arranged as the projecting metal. 



I have found this kind of battery superior to those where all the metal 

 surface engaged radiating forms part of the electrical circuit, and I 

 believe it to be solely due to the large radiating surface placed beyond 

 the electrical circuit, where it effects the required difference of tenipera- 

 ture betwixt the joints, with a short path for the thermo electricity de- 

 veloped. 



* See Introduction to Chemical Philosophy, p. 466. 



