APPENDIX TO MEMOIR OF PELTIER. 185 



Peltier lias also proved tliat a ciuTcnt endowed witli a great intensity is iden- 

 tical with a current wliicli possesses but a feeble one, and that these currents of 

 great and feeble intensity produce the same effects on bodies when they traverse 

 them in equal quantities. He has established, by two series of new experiments, 

 the one dynamic, tiie other static, that in a battery well constructed there is a 

 neutralization of all the intermediate electricities ; that all the negative portions 

 are neutralized by equal positive portions proceeding from the pairs in front of 

 them, and that there are no free electricities but those of the extreme elements, 

 which, to become neutralized, have only the arc interposed between them, or a 

 return by the battery. Finally, he proved that it was always by its quantity 

 that a current acted, but on the condition of being accompanied by a sufficient 

 intensity ; for, without this intensity, the current couhl not pass in suitable quan- 

 tit}^ to produce action ; the resistance of the conductors would oppose itself to 

 that action. 



We proceed now to indicate the chief experiments by means of which Peltier 

 has demonstrated the principles above stated. These experiments are almost 

 all derived from the memoir of Peltier, already cited, on tlie electric quantity 

 and intensity. 



Experiments of Peltier relative to the quantity and intensitf/ of a current. — 

 If we take a voltaic pair consisting of two fine wires, zinc and copper, immerse it in 

 common water, and complete the circuit by a copper wire of the length of 300 

 metres, there is a continuous current in this closed circuit. If this wire be pre- 

 sented above a magnetized needle, the needle will not be deflected from its posi- 

 tion of equilibrium in the magnetic meridian ; the action of the current will not 

 be powerful enough to overcome the influence of the terrestrial magnetism. 

 But if this needle be surrounded with 100 or 200 coils of the long wire, there 

 will be at once a notable deviation ; if the number of coils be increased to 2,000, 

 the deviation will extend as far as 60 degrees. 



In this experiment, the primitive current has not been changed or altered. 

 We have only produced a factitious quantity by conducting it 2,000 times around 

 a magnetized needle, so that it may act as the primitive quantity muhii)lied l»y 

 2,000. It is very evident in this experiment that it is by the quantitif that the 

 power of action has been enhanced, and not by some other modilication. It is, 

 therefore, through its quantity that a current acts on the magnetized needle. 



If, now, we take a thermo-electric pair, zinc and copper of live square milinie- 

 tres, heat one of the solderings to 40 degrees, and complete the circuit by tho 

 sort of multiplier which Ave had previously formed, the needle \A\\ be not at all 

 deflected ; the electricity will not pass. But if we retrench 1,800 coils and 

 shorten the conductor to this extent, the multiplier, now reduced to 200 coils, 

 will begin to give notable deviations. If we reduce it to 10 coils, the deviation 

 Avill be considerably augmented. If, in tine, we reduce it to a single coil, 

 fonned of a strip of copper containing as much substance as the 2,000 coils, the 

 deviation may proceed even to 60 degrees. 



The quantity of electricity produced in this experiment by the thermo-electric 

 pair is evidently 2,000 times greater than that of the above hydro-electric pair, 

 since we ol)tain the same deviation with a single coil as with the factitious quan- 

 tity given l)y the reduplication of. the coils. Nor is this all : in the first experi- 

 ment the length of the conducting wire was easily traversed by the hytlro- 

 electric current ; the inertia of the matter was overcome without diiliculty and 

 without appreciable loss of the cun-ent. In the second experiment this inertia 

 could not be overcome ; the power of action was insufficient, and it was neces- 

 sary to reduce the circuit to a very small length for the electricity to be able to 

 traverse it. There are two quite distinct conditions, then, which we must not 

 (;onfound : to act by the quantity, or to overcome the resistance of the conduct- 

 ors by a power independent of the quantity, and which Peltier called intensity, 

 reserving tho name of tension for static electricity. 



