Nov. 1845.] Rotation of a Ray of Light by Electric Force, 303 



list of which would be too long to give here, since the great 

 conclusion was, that the exceeding diversity of substance 

 caused no exception to the general result, for all the bodies 

 showed the property. It is indeed more than probable, that 

 in all these cases the water and not the other substance 

 present was the ruling matter. The same general result was 

 obtained with alcoholic solutions. 



2186. Proceeding from liquids to air and gaseous bodies, 

 I have here to state that, as yet, I have not been able to de- 

 tect the exercise of this power in any one of the substances in 

 this class. I have tried the experiment with bottles 4 inches 

 in diameter, and the following gases: oxygen, nitrogen, 

 hydrogen, nitrous oxide, defiant gas, sulphurous acid, mu- 

 riatic acid, carbonic acid, carbonic oxide, ammonia, sulphu- 

 retted hydrogen, and bromine vapour, at ordinary tempe- 

 ratures; but they all gave negative results. With air, the 

 trial has been carried, by another form of apparatus, to a 

 much higher degree, but still ineffectually (2212.). 



2187. Before dismissing the consideration of the substances 

 which exhibited this power, and in reference to those in which 

 it was superinduced upon bodies possessing, naturally, rota- 

 tive force (2165. 2231.), I may record, that the following are 

 the substances submitted to experiment: castor oil, resin oil, 

 oil of spike lavender, of laorel, Canada balsam, alcoholic solu- 

 tion of camphor, alcoholic solution of camphor and corrosive 

 sublimate, aqueous solutions of sugar, tartaric acid, tartrate 

 of soda, tartrate of potassa and antimony, tartaric and boracic 

 acid, and sulphate of nickel, which rotated to the right-hand; 

 copaiba balsam, which rotated the ray to the left-hand ; and 

 two specimens of camphine or oil of turpentine, in one of which 

 the rotation was to the right-hand, and in the other to the left. 

 In all these cases, as already said (2165.), the superinduced 

 magnetic rotation was according to the general law (2160.), 

 and without reference to the previous power of the body. 



2188. Camphor being melted in a tube about an inch in 

 diameter, exhibited high natural rotative force, but I could 

 not discover that the magnetic curves induced additional force 

 in it. It may be, however, that the shortness of the ray length 

 and the quantity of coloured light left, even when the eye- 

 piece was adjusted to the most favourable position for dark- 

 ening the image produced by the naturally rotated ray, ren- 

 dered the small magneto-power of the camphor insensible. 



^[ ii. Action of electric currents on light. 



2189. From a consideration of the nature and position of 

 the lines of magnetic and electric force, and the relation of a 

 magnet to a current of electricity, it appeared almost certain 



