London Electrical Society. 65 



When acid water was electrolyzed, the odour was not produced, 

 but with a platinum anode : this was also the case with muriate of 

 soda ; but the odour was not detected until the gas was first washed 

 in ammonia to absorb the chlorine, which appeared to disguise the 

 ozone. When the gases obtained by electrolysis were exploded in 

 proper proportions in the eudiometer, the odour disappeared with 

 the gas ; it also disappeared from oxygen after the Leyden spark 

 had been sent through it. The author here gives certain conclu- 

 sions to which he is led, the chief being his opinion, that under cer- 

 tain conditions all metals develope it. 



2nd. " On the tendency of Electricity to promote the Growth of 

 Plants." By Mr. Pine. 



The general conditions chiefly dwelt upon in this the writer's 

 fourth communication, are the positive state of the air, and the ne- 

 gative state of the soil. He brings many cases in proof that the 

 luxuriancy of vegetation is in proportion to these states. A droop- 

 ing narcissus being removed into a room, the atmosphere of which 

 was constantly surcharged with electricity from a machine often 

 used for medical purposes, revived and attained the gigantic height 

 of thirty-six inches. Mustard-seed, in a pot whose soil was nega- 

 tively electrized, vegetated with greater vigour than seed in a posi- 

 tive soil, and far greater than seed in its natural condition. 



3rd. " On the Powers of a Water Battery." Bv H. M. Noad 

 M.E. S. ' 



A fact worthy of notice in this communication is, that two cop- 

 per discs are connected with the terminals of a series of 500, and 

 a pith ball insulated and suspended between the two vibrates with- 

 out cessation : it had been in motion for a fortnight, with the ex- 

 ception of a few intervals, when it was removed to give place to 

 other experiments. Mr. Noad mentions that he has erected, but on 

 a smaller scale, an apparatus for atmospheric observations similar 

 to that of Mr. Weekes. 



4th. " Note upon a Phrenomenon presented by solution of Ni- 

 trate of Silver, decomposed by the Current." By M. Ch. Matteucci. 

 (Translated by the Secretary from Les Archives de U Electricite.) 



The author of this paper has observed that the blacic deposit ob- 

 tained on the cathode, in the electrolysis of this salt, instantaneously 

 becomes ivhite, when the current ceases ; that it does not occur ex- 

 cept when the solution is weak, because from strong solutions cry- 

 stalline silver is at once deposited ; that if a portion of the dej)Osit, 

 after it has become white, be suspended between the electrodes while 

 the current i)asses, those portions towards the anode again become 

 black, if tiie exiK-riment is made in a solution of the nitrate, but not 

 if in mere acid water ; it will, however, occur if a mere droj) of ni- 

 trate is added to this latter solution. If a plate of glass is interposed 

 between the electrodes, the pha;nomenon does not occur ; this the 

 author attributes to the great reduction of intensity. In conclusion 

 the author suggests, "that the black deposit is formedof oxide of silver, 

 which IS preserved by the passage of the current, and which, when 

 the current ceases, passes immediately to the metallic condition " 



Fhil. Mag. S. 3. Vol. 20. No. 128. Jcai. 1812. F 



