developed by Muscular CofUraclion. 57 



a very weak current. But experience unfortunately proves 

 that gold and platinum are under these circumstances as im- 

 pressionable as brass, if I may be allowed to use such an ex- 

 pression. I have repeated M. Reymond's experiment several 

 times, both following rigidly and varying his method of pro- 

 ceeding. 



I first wished to ascertain whether the instrument, which I 

 had not yet used, was sensible or not to changes of tempera- 

 ture. For this purpose, I heated one of the places at which 

 it was soldered to the melting-point of wax, the communication 

 being established by the hands between the two plates ; I also 

 augmented the temperature of one of the two solutions of 

 common salt, by immersing in it glass tubes filled with boiling 

 water, the communication being always kept up by the hands; 

 in neither case did I observe the slightest deflection, which 

 might be anticipated from the known properties of thermo- 

 electric phaenomena; nevertheless it appeared to me of use to 

 verify this in the present instance. To avoid the effect of a 

 more or less deep immersion of the metallic plates, in conse- 

 quence of the introduction of the fingers, 1 partly covered 

 these plates with black wax, so that the uncovered surface was 

 always in contact with the solution. 



As regards the fingers, I attempted to immerse them to the 

 same extent in all the experiments, having found that in 

 plunging successively one, two or three, or more fingers, or a 

 single finger to a greater or less depth, the intensity of the 

 deflections varied. This result indeed had been anticipated. 

 I had even had some long kinds of copper thimbles gilt, so as 

 to regulate the immersion better. But I abandoned this 

 method of proceeding, because it differed too much from that 

 adopted by M. Du Bois Reymond. 



In experiments made according to M. Du Bois Reymond's 

 process, the alternate contraction of each arm has sometimes 

 afforded deflections in the same, sometimes in the opposite 

 direction. 



In other experiments, each arm was successively contracted 

 out of the water, and on each contraction the vessels were 

 connected by means of the fingers. In others, large capsules 

 were used, so as to allow more freedom of motion of the hands, 

 and so as to permit the immersion of the closed hands, either 

 contracted or not contracted. The results of these two series 

 of experiments are sometimes favourable, sometimes contrary 

 to the assertion of M. Reymond. The necessity of multiply- 

 ing the experiments is very distinctly shown in this case. 

 The results of two or three experiments agree with the results 

 announced by M. Reymond ; and then, if they are continued, 

 opposite results are obtained. A singular fact is also remarked 



