of Magnetism : with Notes by Mr. Faraday. 409 



The galvanometer which should be used for the experiments 

 of this section should be very sensible. And I repeat ou 

 this occasion what I have elsewhere said relative to these 

 instruments : two systems may be adopted to obtain maxi- 

 mum effects ; the one for hydro-electric currents, the other 

 for thermo-electric currents. The galvanometer of my ther- 

 mo-multiplicator is ofthe latter kind, and precisely that which 

 is best in the present researches *. The reason will be evi- 

 dent, by observing that the new currents of Faraday are en- 

 tirely developed in metallic circuits, like the thermo-electricity 

 of Dr. Seebeck, and that, also like those of thermo-electricity, 

 they pass with difficulty through humid conductors. 



4. Electric Tension. 



The trials which we have as yet made on this new class 

 of currents, to obtain by the electrometer the ordinary signs 

 of tension, have not conducted us to any positive result: but 

 the means which we have employed are far from satistying us 

 fully. We are preparing otheis for the purpose of attacking the 

 question with more efficacious means. We shall then extend 

 the research to thermo-electric combinations, which deserve 

 to be studied in the same point of view, as they have never 

 yet presented sensible signs of electric tension. We shall also 

 try with these latter currents to obtain the spark under fa- 

 vourable circumstances; but we cannot but confess that at 

 present we doubt, and consider the thermo-electric currents 

 as in their nature the least fitted to produce either tension 

 or a spark, as we will explain in due time and place. 



5. Chemical a7id Physiological Effects {Exp. Res. 22. 56. 133.). 



The new currents of Faraday pass, although with diffi- 

 culty, through humid conductors. So says the notice; and 

 such is the fact, as may be readily verified by introducing a 

 conductor oi'that kind into the circuit of the electro-dynamic 

 spiral [Exp. Res. 20. 23. 33. 56.). In the case of other known 

 currents, I have demonstrated elsewhere that there is always 

 chemical decomposition when they pass liquid conductors; and 

 that however feeble they may be, the decomposition is always 

 assured by their transit through the fluid. It is therefore very 

 probable that the new currents will produce the phenomena 

 of decomposition, but their distinctive character of brief dura- 

 tion must not be forgotten [Exp. Res. 59, &c.). I believe that 

 the time, however short, is still sufficient for decom|)()sition ; 

 but 1 will not venture anything before I have interrogated that 

 grand master in everything, — experiment. 



• XohUi. Bib. Univ., .hiUlcl 1830, p. 275. 

 N. S. Vol. 1 1. No. 66. Jutie 1832. 3 G The 



