436 Dr. Faraday's Experimental Researches in Electricity. 



bubbles had appeared upon the plate B, but none upon plate A. 

 The plates were washed in distilled water, dried, and re- 

 weighed. Plate B weighed 1 4-8*3 grains, as before, having 

 lost nothing by the direct chemical action of the acid. Plate A 

 weighed 1 54*65 grains, 8*45 grains of it having been oxidized 

 and dissolved during the experiment. 



866. The hydrogen gas was next transferred to a water- 

 trough and measured; it amounted to 12*5 cubic inches, the 

 temperature being 52°, and the barometer 29*2 inches. This 

 quantity, corrected for temperature, pressure, and moisture, 

 becomes 12*15453 cubic inches of dry hydrogen at mean tem- 

 perature and pressure : which, increased by one half for the 

 oxygen that must have gone to the anode, i. e. to the zinc, 

 gives 18-232 cubic inches as the quantity of oxygen and hy- 

 drogen evolved from the water decomposed by the electric 

 current. According to the estimate of the weight of the 

 mixed gas before adopted (791.), this volume is equal to 

 2*3535544 grains, which therefore is the weight of water de- 

 composed ; and this quantity is to 8*45, the quantity of zinc 

 oxidized, as 9 is to 32*31. Now taking 9 as the equivalent 

 number of water, the number 32*5 is given as the equivalent 

 number of zinc; a coincidence sufficiently near to show, what 

 indeed could not but happen, that for an equivalent of zinc 

 oxidized an equivalent of water must be decomposed*. 



867. But let us observe how the water is decomposed. It 

 is electrolyzed, i. e. is decomposed voltaically, and not in the 

 ordinary manner (as to appearance) of chemical decomposi- 

 tions; for the oxygen appears at the anode and the hydrogen 

 at the cathode of the decomposing body, and these were in 

 many parts of the experiment above an inch asunder. Again, 

 the ordinary chemical affinity was not enough under the cir- 

 cumstances to effect the decomposition of the water, as was 

 abundantly proved by the inaction on plate B ; the voltaic 

 current was essential. And to prevent any idea that the che- 

 mical affinity was almost sufficient to decompose the water, 

 and that a smaller current of electricity might, under the cir- 

 cumstances, cause the hydrogen to pass to the cathode, I need 

 only refer to the results which I have given (807. 813.) to 

 show that the chemical action at the electrodes has not the 

 slightest influence over the quantities of water or other sub- 

 stances decomposed between them, but that they are entirely 

 dependent upon the quantity of electricity which passes. 



868. What, then, follows as a necessary consequence of the 

 whole experiment? Why, this: that the chemical action upon 



* The experiment w«s repeated several times with the same results. 



