132 Mr. M. Donovan on the supposed Identity of the Agent 



about half an inch square, was moistened with solution of sul- 

 phate of soda, and placed on the edge of a glass plate within 

 about two inches of a point connected with the discharging 

 train. The end of a decomposing wire proceeding from the 

 prime conductor rested on the tui'meric paper. The machine 

 being put in action, positive electricity passed through the de- 

 composing mre, in at one end of the turmeric paper, and out 

 again at the other end towards the distant point of the dischar- 

 ging train*. Here he expressly admits that nothing but posi- 

 tive electricity acted at the two extremities of the very small bit 

 of tm-meric paper ; no negati\"e electricity or negative pole could 

 be concerned ; yet after forty or fifty turns of the machine, the 

 red stain on the end of the turmeric paper which discharged 

 positive electricity towards the point indicated the presence of 

 alkali derived from the decomposition of the sul])hate of soda. 

 It is therefore true that one pole, and one kind of electricity 

 only, here produced a decomposition, which therefore is of a 

 different natm-e from one effected by voltaic electricity. 



This was still more evident in an experiment where a large 

 strip of turmeric paper, wet with solution of sulphate of soda, 

 was hung from the prime conductor. On working the machine, 

 alkali was developed at that part where the positive electricity 

 was discharged from the paper f. 



In these cases, the alkali appeared at what, in point of fact, 

 was the positive pole as it was canying positive electricity, con- 

 trarily to the voltaic law, according to which it should have ap- 

 peared only at the negative pole if there had been one. The 

 experiments, therefore, instead of supporting, seem to discounte- 

 nance the alleged identity. 



In other experiments no pole whatever was employed, positive 

 electricity being received from the air at one end of the papei", 

 and the same electricity discharged into the air from the other 

 end : surely there is here no analogy with voltaic decomposition. 



Professor Faraday nowhere refers to the employment of a 

 positive and negative pole in any one experiment ; on the con- 

 ti-aiy, he says that the discharging train with its point "repre- 

 sents" the negative pole J. 



The objections here made may be simplified and reduced to 

 one by the following variation of the experiment on decomposi- 

 tion. I placed a bit of turmeric paper well soaked in solution 

 of sulphate of soda, and the redundant liquid drained off, on the 

 positive conductor of a powerful electric machine. The end of 



* " The machine was then worked, the positive electricity passing into 

 the turmeric paper at the point p, and out at the extremity «."— Researches, 

 par. 462. 



t Ibid. par. 4&4. % Ibid. par. 454. 



