196 Prof, Marianini's Examination of an Experiment 



minutes of repose I closed it; the needle pointed exactly to 

 thirty-five, and stopped at the eleventh degree. The circle 

 being again interrupted, and the liquid stirred with a feather, 

 the needle deviated to thirty-nine, and finally stopped at 

 about thirteen degrees. 



From these and other similar experiments I have seen that 

 the agitation of the liquid, after the electromotor has acted for 

 some time, produces an increase of strength in the current 

 independently of the repose. Since in the first, for example, 

 of the above experiments, by the inaction only the pair would 

 have recovered strength to make the needle deviate thirty-two 

 degrees, whilst with the repose and the agitation of the liquid 

 combined the force was such as to make it deviate thirty- 

 eight degrees. Therefore six degrees of deviation above the 

 thirty-two, or the degree of strength expressed by them, was 

 procured by the agitation of the liquid. In the second expe- 

 riment, then, the force recovered by the agitation of the liquid 

 is expressed by four degrees of deviation above the thirty- 

 five. 



III. I convinced myself in another way also of this advan- 

 tage, which agitating the liquid with a feather confers upon 

 the current, by observing the time required for the needle of 

 the galvanometer to recede a given number of degrees from 

 the point where it had ceased to oscillate ; since when the 

 liquid was agitated the time was generally greater than when 

 it was not agitated, and especially if the liquid itself was in 

 any degree a conductor, as for example, spring water, or 

 water rendered slightly saline, which also shows that with the 

 agitation of the liquid we put an obstacle to the cause which 

 tends continually to slacken the current when the circuit is 

 complete. 



It is true that this increase of strength caused by agitating 

 the liquid is but trifling when compared with that which is 

 caused by repose. At all events the proposition of Faraday 

 is not the less true, although he may not have remarked that 

 the greater part of the increase of strength is owing to the re- 

 pose, and the less to the agitation of the liquid : and so much 

 the more founded is the proposition of the learned Englishman, 

 that these tv;o causes of increase of strength resolve them- 

 selves into one; since even simple repose causes the voltaic 

 pair to acquire force, probably because the liquid freeing the 

 neutralized acid detaches it from the zinc. 



IV. The liquid being agitated, the chemical action acquires 

 new vigour, because a new stratum of acid comes into contact 

 with the zinc. When indeed this experiment is made by im- 

 mersing the pair in distilled water (in which case the eftects 



