667 



" On the reabsorption of the Mixed Gases in a Voltameter." By 

 Professor M. H. Jacobi, in a letter to Michael Faraday, Esq., F.R.S. 

 Communicated by Dr. Faraday. 



The author found that if the mixed gases developed from the 

 decomposition of water by a voltaic current, be allowed to remain 

 in the voltameter in which they were collected, in contact with the 

 fluid which produced them, they by degrees diminish in volume, 

 and ultimately disappear by being absorbed by the fluid. He has 

 not yet fully determined the precise conditions on which this phe- 

 nomenon depends ; but he is inclined to think that it is owing to a 

 portion of the mixed gases, diff'used throughout the whole liquid, 

 coming into contact with the platinum plates, and being recombined 

 on the surface of those plates ; and this process being renewed with 

 every fresh portion of the gases which takes the place of the former, 

 the whole of the gases are thus reconverted into water. 



March 4, 1847. 



The MARQUIS OF NORTHAMPTON, President, in the Chair. 



Charles Brooke, Esq. was elected a Fellow of the Society. 



" Researches into the effects of certain Physical and Chemical 

 Agents on the Nervous System." By Marshall Hall, M.D., F.R.S., 

 &c. 



The professed object of the author, in the present paper, is " to 

 detail the results of an investigation of the phenomena and the laws 

 of production and action of certain secondary or induced conditions 

 of the nervous system, which are eff'ected by a voltaic, and proba- 

 bly by any other electric current, but persistent after the influence 

 of that current is withdrawn." This condition he designates by the 

 new term electrogenic, as describing at once the origin and the inde- 

 pendence of that condition. On the present occasion he confines 

 himself to the subject of the electrogenic condition of the muscular 

 nerves, postponing to future inquiries that of the incident nerves 

 and of the spinal marrow ; and also the modes of action of other 

 physical and chemical agents, such as mechanical injury, heat and 

 cold, strychnine, and the hydrocyanic acid. 



The bones and muscles of the brachial lumbar and pelvic regions 

 of a frog, being isolated from all the other parts of the body, except- 

 ing only by means of their respective brachial and lumbar nerves, 

 which were perfectly denuded on all sides, and raised from the glass 

 on which the limbs were laid, a voltaic current from a pair of the 

 " couronne de tasses" was passed downwards through the nerves, in 

 a direction from their origin in the spinal marrow towards their ter- 

 minations in the muscles. Energetic muscular movements were at 

 first excited ; and the current was thus continued during the space 

 of five, ten, or fifteen minutes, and at the end of this period was 



