UPON GASES AND LIQUIDS. 56/ 



poles) would be expelled and constantly replaced by more, which 

 entered at those spots where the action was more feeble. The 

 flame, Avhen brought laterally into proximity with the surfaces 

 of the poles, was repelled ; and when I inserted a lamina of mica 

 between the flame and the halves of the keeper, the flame was 

 less powerfully repelled. But as the proximity of the lamina of 

 mica exerts a disturbing influence, I shall not at present venture 

 to decide whether the diminution of the repulsion should be 

 ascribed to a current of air or not, although it would have been 

 very interesting to have directly proved the diamagnetism of air 

 in this manner. 



32. If air is diamagnetic, M'hich we can hardly doubt, it 

 is repelled by the poles of the magnet, and hence is rarefied 

 when in proximity to them. This rarefaction however cannot be 

 detected by means of the barometer, because the air to a certain 

 extent simultaneously acquires a greater state of tension. For 

 this purpose I therefore adopted another method, and took a 

 glass cylinder about 90 millims. in length and 30 millims. in 

 breadth, which^vas so depressed in the middle as to allow of the 

 conical apices of the halves of the keeper (B) being placed in the 

 depressions, and which were then only a few millimetres apart. 

 A narrow tube was fused to the cylinder, and the air contained 

 in it confined by placing a drop of alcohol in the tube, so as to. 

 allow of its being decided as to the magnetism or diamagnetism 

 of the enclosed air by the motion of the drop on closing the 

 circuit. Although no definite result ensued, 1 think of repeating 

 the experiment under different circumstances and with greater 

 intensity of force. 



§ 2. On the Magnetic or Diamagnetic Deportment of Liquids. 



33. When masses of fine iron filings are placed upon the ap- 

 proximated poles of a magnet, in consequence of their being 

 attracted by these poles they form heaps, which assume different 

 configurations according to the form of the poles and their 

 distance apart. Hence magnetic fluids must be affected in a 

 corresponding manner. Starting from this point of view, I first 

 plr.ced different liquids in a watch-glass above the poles of the 

 electro-magnet ; and the phaenomena which were observed cor- 

 responded perfectly to my expectation. The liquids were more 

 or less strongly attracted towards those points at which the mag- 

 netic action is strongest, hence principally towards the angles of 



