530 Intelligence and Miscellaneous Articles. 



quickly attains a position of permanent magnetic equilibrium. When 

 the galvanic current is stopped, the index returns and recovers its 

 original position. The magnetic attraction is in this case shown by 

 a very sensible effect, that is to say, by a displacement of four or live 

 centimetres. This is supposing that the column of fluid is of suffi- 

 cient length to produce the maximum of action, but very short 

 columns may be employed. 



When a diamagnetic fluid is to be tested, and the experiment is 

 arranged as just described, the index is repelled by the electro- 

 magnet ; but in this case the movement is less energetic, and the 

 index only moves to a short distance, as the diamagnetic action is 

 weakened in projiortion to the distance of the liquid. If it be desired 

 to give the experiment a very marked character, and even as distinct 

 as for magnetic attraction, the index is to be brought between the 

 polar pieces so as to cover their whole length ; then, as soon as the 

 electric current passes, the liquid is strongly repelled, and does not 

 stop until it has passed the polar pieces to a greater or less distance. 

 This movement, which may be produced to the extent of four or five 

 centimetres, can leave no doubt as to the consequences of the expe- 

 riment. 



Tlie sensibility of this kind of magnetoscope is sufficient to enable 

 one to recognize the diamagnetic property of w'ater, even when em- 

 ploying onlj' a single Bunsen's element of middling energy. 



With eight Bunsen's elements, a solution of chloride of manga- 

 nese remains in a position of permanent magnetic equilibrium, even 

 when the tube is made to slide rapidly in the direction of its axis. 



If the pressure of the air be increased on one of the extremities of 

 the fluid column, the index retrogrades between the polar pieces, 

 and it may thus be brought to a position of unstable equilibrium. 

 The excess of pressure which 1 have employed to produce this effect 

 was about y^irth of an atmosphere. This number shows the mag- 

 netic energy of the chloride of manganese, and at the same time that 

 the magnetoscope may be readily converted into an apparatus of 

 measurement. 



As a last instance of the sensibility of this method, I vi'ill mention 

 .that the solution of chloride of manganese diluted with one hundred 

 times its volume of water still retains appreciable magnetic proper- 

 ties ; but if it be diluted with twice this quantity, the magnetism of 

 the salt is concealed, the diamagnetism of the water becoming pre- 

 dominant. 



Theory shows that the elevation of a fluid in a capillary tube is in 

 an inverse ratio to its weight. Hence we may believe that magnets 

 may exert an appreciable influence upon the capillary elevation of 

 liquids. I'his I have verified. One of the branches of a capillary 

 siphon is placed between the poles of an electro-magnet; the capil- 

 lary surface of a magnetic liquid is brought a little below the polar 

 pieces and the electric current is then passed : the capillary surface 

 immediately rises to a new position of equilibrium. With a dia- 

 magnetic fluid, of whicli the capillary surface is brought to a level 

 with the poles, we get a depression of the column. — Compics Rendus, 

 March 20, 1854, p. 562. 



