the Luminiferous Ether. 231 



fluids ? If, however, we consider the particles of the air con- 

 cerned in the propagation of light, we have to make no fresh 

 assumption, as we already know nitrogen to be very feebly 

 diamagnetic and oxygen paramagnetic. The particles of these 

 gases are affected by contiguity to the pole of the magnet; 

 and this kind of affection is such as to cause the molecules to 

 vibrate in certain planes : hence the light is polarized. 



Finally, let us look at the explanation offered by the ether 

 theory to two of the chemical actions of light as representa- 

 tives of most of the chemical effects of light. We will take the 

 reduction of silver salts and the decomposition of C0 2 into its 

 elements by the action of light on the chlorophyll of plants. 

 Scheele discovered that when chloride of silver was exposed to 

 light, a black powder, insoluble in nitric acid, was formed ; 

 and at the same time free hydrochloric acid was produced. 

 The black powder he concluded to be metallic silver. He also 

 made the important discovery that the violet rays were far 

 more active in producing this reduction than the other rays. 

 Here, then, we have three distinct results to account for, viz. : — 

 1st, the production of the black powder ; 2nd, the formation 

 of hydrochloric acid ; and, 3rd, the superior power of the violet 

 rays. The ether theory says that the vibration of the ether 

 shakes asunder the bond of chemical union; that is, the 

 vibrations of the medium in which the molecules of the ar- 

 gentic chloride are imbedded causes the separation of the atoms 

 of the molecules. This explanation seems at once insufficient 

 and unnecessary. It is insufficient for this reason : it does 

 not seem probable that the vibrations of an intermolecular 

 medium should be able to cause an atomic separation. It is 

 quite possible to conceive that the molecules are caused to 

 vibrate by the vibrations of the surrounding ether ; but that 

 the individual atoms of these molecules are caused to vibrate, 

 and that with different velocities, or otherwise no separation can 

 occur, seems improbable. That this vibration of the atoms 

 may occur it is necessary to assume that the ether is inter- 

 atomic instead of intermolecular. If we make this additional 

 assumption, we stretch to the point of breaking an already 

 " elastic " theory, and we render much more difficult of expla- 

 nation the combination of bodies produced by the action of light. 

 The above explanation seems unnecessary, because we have 

 only to assume that the atoms of bodies are capable of vibrating 

 at a great velocity to account for these experiments in a simple 

 and most satisfactory manner. The latter portion of this paper 

 is devoted to the working-out of this assumption. 



Continuing our investigation of this experiment further, 

 we notice that colourless chloride of silver has been converted 



