Nov. 184-5.] Rotation of a Ray of Light by Electric Force. 307 



and, that by using long helices, substances may be submitted 

 to this kind of examination which could not be placed in suf- 

 ficient length between the poles of magnets (2150.). 



2203. A tube of water as long as the Woolwich helix 

 (21.92.), but only 0'4 of an inch in diameter, was placed in 

 the helix parallel to the axis, but sometimes in the axis and 

 sometimes near the side. No apparent difference was pro- 

 duced in these different situations ; and I am inclined to be- 

 lieve (without being quite sure) that the action on the ray is 

 the same, wherever the tube is placed, within the helix, in re- 

 lation to the axis. The same result was obtained when a 

 larger tube of water was looked through, whether the ray 

 passed through the axis of the helix and tube, or near the 

 side. 



2204. If bodies be introduced into the helix possessing, 

 naturally, rotating force, then the rotating power given by the 

 electric current is superinduced upon them, exactly as in the 

 cases already described of magnetic action (2165. 21S7.)« 



2205. A helix, twenty inches long and 0'3 of an inch in 

 diameter, was made of uncovered copper wire, 0*05 of an inch 

 in diameter, in close spirals. This was placed in a large tube 

 of water, so that the fluid, both in the inside and at the out- 

 side of the helix, could be examined by the polarized ray. 

 When the current was sent through the helix, the water within 

 it received rotating power ; but no trace of such an action on 

 the light was seen on the outside of the helix, even in the line 

 most close to the uncovered wire. 



2206. The water was inclosed in brass and copper tubes, 

 but this alteration caused not the slightest change in the 

 effect. 



2207. The water in the brass tube was put into an iron 

 tube, much longer than either the Woolwich helix or the 

 brass tube, and quite one-eighth of an inch thick in the side ; 

 yet when placed in the Woolwich helix (2192.), the water 

 rotated the ray of light apparently as well as before. 



2208. An iron bar, one inch square and longer than the 

 helix, was put into the helix, and the small water-tube (2203.) 

 upon it. The water exerted as much action on the light as 

 before. 



2209. Three iron tubes, each twenty-seven inches long and 

 one-eighth of an inch in thickness in the side, were selected 

 of such diameters as to pass easily one into the other, and the 

 whole into the Woolwich helix (2192.). The smaller one was 

 supplied with glass ends and filled with water; and being 

 placed in the axis of the Woolwich helix, had a certain 

 amount of rotating power over the polarized ray. The 



Y2 



