with Formula for ascertaining its power, 253 



minished and the current of one battery will pass through it. 

 The observations made with regard to the reduction of alloys 

 in the case of e apply equally to (a), for the first element will al- 

 ways be removed in the manner which affords least resistance. 



(r) varies very much from the extent of the interposed fluid, 

 and its conducting power being very different in each case. It 

 varies much in different batteries. Sometimes r is a very com- 

 plex quantity, as when two or more solutions of different con- 

 ducting power are used between the combination of one ele- 

 ment of a compound and the evolution of the second. In 

 Daniell's battery, for instance, it is made up of three parts, 

 not only the resistance offered by dilute sulphuric acid and 

 solution of sulphate of copper, but also a resistance offered 

 by the interposed diaphragm. It might be made up of a far 

 greater number of parts, for different parts may be of differ- 

 ent temperatures, which alone (if the temperature interferes 

 with the conducting power) would cause r to be complex. 

 (r) becomes enormously increased when the force is compelled 

 to travel round a corner. 



(c) the resistance of the connecting part of the arrange- 

 ment is generally in batteries very slight, because we select 

 metals which conduct pretty freely ; (c) may be very complex 

 by being made of a variety of conducting substances; thus, if 

 the connexions are made of wires of different kinds of metal, 

 a different resistance is offered by each, (c) in every battery, 

 is generally made up of three parts, the conducting power of 

 the positive and negative plates, and the intervening connect- 

 ing wires. 



(e) the resistance to the removal of the second element *, is 

 generally very great, affording a considerable obstacle in all 

 cases, but the differences in this respect are very remarkable. 

 Ordinarily (e) is a simple quantity, but becomes complex when 

 the hydrogen is removed in a variety of ways at the same mo- 

 ment. It becomes a curious question to ascertain whether 

 (e) might ever be made a plus quantity. If the force pro- 

 ceeds from analyis, then the use of any body having great 

 affinity for the second element might cause the current to be 

 increased. If from synthesis, and this is most probable, if 

 not absolutely certain, (e) can never be a plus quantity, but 

 always a minus. In the removal of the second element by 

 decomposition of another compound body, it is by no means 

 uncommon for a voltaic circuit to be formed. In Grove's 



* The term second here may require explanation, for it is only used in 

 contradistinction to the term first, which is applied to that element which 

 by combination forms F. Either element of a compound may be first or 

 second, according as it may happen to assist in the propagation of the force. 



