ON MUSCULAR CONTRACTION. 203 



Notwithstanding our long acquaintance with the phe- 

 nomena of galvanism, there are but few who entertain a 

 correct idea of the enormous amount of electricity whicli 

 is necessary to the existing conditions of matter. To 

 Faraday we are indebted for the first clear set of deduc- 

 tions from a series of inductive researches, which are of 

 the most complete order. He has proved, by a series 

 of exceedingly conclusive experiments, that if the elec- 

 trical power which holds a grain of water in combination, 

 or which causes a grain of oxygen and hydrogen to unite 

 in the right proportions to form water, could be collected 

 and thrown into the condition of a voltaic current, it 

 would be exactly the quantity required to produce the 

 decomposition of that grain of water, or the liberation of 

 its elements, hydrogen and oxygen.* 



By direct experiment it has been proved that one equi- 

 valent of zinc in a voltaic arrangement evolves such a 

 quantity of electricity in the form of a current, as, pass- 

 ing through water, will decompose exactly one equivalent 

 of that fluid. The law has been thus expressed : The 

 electricity which decomposes, and that which is evolved 

 by the decomposition of a certain quantity of matter, are 



* Faraday's Experimental Researches on Electricity. This 

 philosopher has shown, by the most conclusive experiments, 

 " that the electricity which, decomposes, and that which is evolved 

 by the decomposition of, a certain quantity of matter, are alike. 

 What an enormous quantity of electricity, therefore, is required 

 for the decomposition of a single grain of water ! We have 

 already seen that it must be in quantity sufficient to sustain a 

 platinum wire -^ of an inch in thickness, red hot, in contact 

 with the air, for three minutes and three quarters. It would 

 appear that 800,000 charges of a Leyden battery, charged by 

 thirty turns of a very large and powerful plate machine, in full 

 action a quantity sufficient, if passed at once through the head 

 of a rat or cat, to have killed it as by a flash of lightning are 

 necessary to supply electricity sufficient to decompose a single 

 grain of water; or, if I am right, to equal the quantity of electri- 

 city which is naturally associated with the elements of that grain 

 of water, endowing them with their mutual chemical affinity." 



