78 Royal Institution : — 



laboratory, the disruption of the luminous discharge in vacuo from 

 400 cells of the nitric-acid battery was obtained : some most beautiful 

 and striking results were obtained from the same battery on the 

 16th inst., on repeating the experiment in the Theatre of the 

 Royal Institution, with its large electro-magnet, Dr. Faraday and 

 Dr. Tyndall being present. 



The large receiver (14G) was placed between the poles of the 

 electro-magnet, the lines of force going through it ; electrodes 

 equatorial. The stratified discharge was extinguished. Subsequently, 

 through the sinking of the battery, or some other cause, the stra- 

 tifications disappeared, and the luminous glow which filled the entire 

 tube remained. On now exciting the magnet with a battery of ten 

 cells, effulgent strata were drawn out from the positive pole, and 

 passing along the upper or under surface of the receiver, according 

 to the direction of the current. On making the circuit of the magnet, 

 and breaking it immediately, the luminous strata rushed from the 

 positive and then retreated, cloud following cloud with a deliberate 

 motion, and appearing as if swallowed by the positive electrode. 



The amount of electricity which passed appeared materially in- 

 creased on exciting the magnet ; once the discharge was so intense 

 as to fuse half an inch of the positive terminal. 



After this had occurred, the discharge no longer passed as before 

 when the terminals of the battery were connected with it ; but on 

 connecting the positive end of the battery with the gas-pipes of the 

 building, the discharge passed. 



The discharge could also be extinguished by the magnet ; and 

 the time necessary to accomplish this, furnished a beautiful indication 

 of the gradual rise and reduction in the power of the electro- 

 magnet. 



ROYAL INSTITUTION OF GREAT BRITAIN. 



March 30, I860.—" On Acids and Salts." By William Odling, 

 Esq., M.B.,F.R.S. 



It is natural to inquire whether the doctrines of series and substi- 

 tutions, which are essential for the association of organic products, 

 may not throw some additional light upon the simpler compounds of 

 mineral chemistry, when viewed as unitary molecules ; and particu- 

 larly upon the relations and properties of the mineral acids and their 

 salts, which have hitherto constituted the strongholds of the electro- 

 chemical, or binary, theory of combination. 



The doctrine of series affirms that chemical compounds may be 

 arranged in series, the successive members of each of which differ 

 from one another in composition by a common increment, and are 

 associated with one another by a certain relation of properties, the 

 exact nature of the relation varying with the nature of the increment. 



The doctrine of substitutions affirms that, in very many chemical 

 compounds, one or more atoms may be displaced by some other 

 atoms or groupings, and that the new bodies, resulting from this 

 displacement, correspond in constitution with the normal bodies 



