360 Mr. Faraday's Experimental Researches in Electricity. 



projected, were parallel, and five sixteenths of an inch apart 

 The upper ends were well connected with the galvanometer 

 wires. Some acid was diluted, and, after various preliminary 

 experiments, that adopted as a standard which consisted of 

 one drop strong sulphuric acid in four ounces distilled water. 

 Finally, the time was noted which the needle required in 

 swinging either from right to left or left to right: it was equal 

 to seventeen beats of my watch, the latter giving one hundred 

 and fifty in a minute. The object of these preparations was 

 to arrange a voltaic apparatus, which, by immersion in a given 

 acid for a given time, much less than that required by the 

 needle to swing in one direction, should give equal deflection 

 to the instrument with the discharge of ordinary electricity 

 from the battery (363. 364?.) ; and a new part of the zinc wire 

 having been brought into position with the platina, the com- 

 parative experiments were made. 



370. On plunging the zinc and platina wires five eighths 

 of an inch deep into the acid, and retaining them there for 

 eight beats of the watch, (after which they were quickly with- 

 drawn,) the needle was deflected, and continued to advance in 

 the same direction some time after the voltaic apparatus had 

 been removed from the acid. It attained the five-and-a-half 

 division, and then returned swinging an equal distance on the 

 other side. This experiment was repeated many times, and 

 always with the same result. 



371. Hence, as an approximation, and judging from mag- 

 netical force only, at present (376.), it would appear that two 

 wires, one of platina and one of zinc, each one eighteenth of 

 an inch in diameter, placed five sixteenths of an inch apart, 

 and immersed to the depth of five eighths of an inch in acid, 

 consisting of one drop oil of vitriol and four ounces distilled 

 water, at a temperature about 60°, and connected at the other 

 extremities by a copper wire eighteen feet long and one eigh- 

 teenth of an inch thick (being the wire of the galvanometer 

 coils), yield as much electricity in eight beats of my watch, or 

 in T ®^ths of a minute, as the electrical battery charged by 

 thirty turns of the large machine, in excellent order (363. 364?.). 

 Notwithstanding this apparently enormous disproportion, the 

 results are perfectly in harmony with those effects which are 

 known to be produced by variations in the intensity and quan- 

 tity of the electric fluid. 



372. In order to procure a reference to chemical action, the 

 wires were now retained immersed in the acid to the depth of 

 five eighths of an inch, and the needle, when stationary, ob- 

 served; it stood, as nearly as the unassisted eye could decide, 

 at 5 J division. Hence a permanent deflection to that extent 



