58 M, Despretz on the Electricity 



in these experiments, viz. that the fingers are influenced much 

 in the same way as metallic conductors ; they lose part of their 

 efficacy by repeated immersions. 



I was desirous of reducing the experiment to a greater 

 amount of simplicity. I replaced the galvanometer by a frog 

 which was properly prepared. Several persons, separately or 

 in connection, having strongly contracted one of their arms, 

 in vain endeavoured to produce convulsive movements, by 

 connecting the two arms by means of the most sensible parts 

 of the animal. Nevertheless with a very fine copper wire and 

 a plate of zinc, without the use of any liquid, very marked con- 

 tractions were produced both before and after the experiment. 



I also endeavoured in vain to deflect a very delicate astatic 

 magnetic needle, by the union of the two hands, whilst one 

 hand was strongly contracted. Finally, I attached a cylin- 

 drical gilt conductor to the back of each hand by silk cord : the 

 contraction of one or the other arm did not perceptibly change 

 the deflection of the needle, which amounted to 10° from the 

 simple contact. The effects of the contact were increased in a 

 marked degree by moistening the back of the hand with a few 

 drops of salt water ; but the contraction of one or the other 

 arm did not produce deflections alternately in one or the other 

 directions. 



These three experiments appear to me to be under more 

 favourable conditions than those of M. Reymond. The re- 

 sults of them are removed from the intervention of the im- 

 mersion of metallic laminae in saline solutions, which is always 

 somewhat obscure. Unfortunately they only furnished nega- 

 tive results. 



In conclusion, if we are only to admit as true that which is 

 clearly demonstrated, we think that the experiments detailed 

 in this note show, that if the contraction of one arm gives rise 

 to an electric current, this current is not appreciable to our 

 present means, at least to those which we have employed. 



We are however far from believing that the tetanic contrac- 

 tion of a limb does not give rise to the decomposition of a 

 certain quantity of electricity. The friction of the parts upon 

 each other, and the unequally heated state of heterogeneous 

 parts would give rise to electric decompositions ; but recompo- 

 sitions ensue immediately. This is probably the case in all the 

 chemical actions which occur in the oeconomy. 



Until chemistry has discovered a metal or an alloy which 

 does not afford any current by the contact of liquid conductors, 

 we shall always be exposed to numerous errors in researches 

 upon the currents of animals and vegetables. 



The galvanometer is a very valuable instrument, but it re- 

 quires a very large amount of skill and prudence on the part 



