Chemistry and Physics. 409 



saline solutions, which is always somewhat obscure. Unfortunately 

 they only furnished negative results. 



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

 demonstrated, we think that the experiments detailed in this nole 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 contraction 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 une- 

 qually heated state of heterogeneous parts would give rise to electric 

 decompositions; but recompositions ensue immediately. This is prob- 

 ably the case in all the chemical actions which occur in the economy. 



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 ani- { 

 tnals and vegetables. 



The galvanometer is a very valuable instrument, but it requires a 

 very large amount of skill and prudence on the part of the experimenter. 

 If it is made but slightly sensible, it only indicates powerful phenome- 

 na ; if it is made very delicate, it obeys the slightest perturbating causes. 

 It is not impossible that a large number of experiments upon the cur- 

 renis in animals and vegetables may merely arise from illusions, and 

 ! that what is attributed to animal and vegetable currents, may be noth- 



ing more than the action of liquids upon the plates of gold or platinum 

 °t galvanoscopes, or upon other different liquids. If the two plates of 

 gold of a galvanoscope are inserted in any direction in a potato which 

 has either budded or not, in an apple, or a cabbage-stalk, or the flesh 

 of beef; if any two parts of the skin, slightly moist, are touched with 

 these same plates, we have currents; if first one and then the oilier 

 plate be withdrawn in succession, and after having washed and wiped 

 «i it be replaced, the current is reversed; if the plates are more or 

 less deeply immersed, reversions may also occur. 



It is possible that the convulsions experienced by the frog from the 

 contact of the crural nerves with the muscles of the legs, may depend 



0n, y upon the heterogeneity of the liquids which moisten these parts 

 h »s possible that the permanence of the direction of what is called the 

 current of the frog may be owing to a different aherability of the ex- 

 tremities of the animal" by the various solutions employed in these ex- 

 periments. In the experiment as arranged for determining the true or 

 false current in the frog, we merely require to substitute for the animal 

 a cord of thread impregnated with common salt, and one of the ends 

 °f which has been touched with the stopper of a bottle of sulphuric 

 a cid, and the other with the stopper of a bottle of nitric acid, to reverse 

 [ he current a irreat manv times, as is done in the case of the current of 

 the frog. b 



There is one experiment upon this subject which would have a cer- 

 tain value without being decisive, it is that of the action of a circuit of 

 frogs upon a magnetic needle. 



} arranged a chain of frogs in the same manner as the pairs of a vol- 

 taic pile are arranged ; this chain traversed a bell-glass, beneath which 



