404 Dr. Faraday on the Diamagnetic conditions 



below the axial line, the stream of smoke is much more 

 affected, being bent outwards ; and if it be brought still higher, 

 there is a point at which the smoke leaves the taper-wick even 

 in a horizontal direction, to go equatorially. If the taper be 

 held so that the smoke-stream passes through the axial line, 

 and then the distances be varied as before, there is little or 

 no sensible effect when the wick is four inches below : but 

 being raised, as soon as the warm part of the stream is between 

 the poles, it lends to divide; and when the ignited wick is 

 about an inch below the axial line, the smoke rises vertically 

 in one column until about two-thirds of that distance is passed 

 over, and then it divides, going right and left, leaving the space 

 between the poles clear. As the taper is slowly raised, the 

 division of the smoke descends, taking place lower down, until 

 it occurs upon the wick, at the distance of O'-i or 0*5 of an 

 inch below the axial line. If the taper be raised still more, 

 the magnetic effect is so great, as not only to divide the stream, 

 but to make it descend on each side of the ignited wick, pro- 

 ducing a form resembling that of the letter W; and at the 

 same time the top of the burning wick is greatly brightened 

 by the stream of air that is impelled downwards upon it. In 

 these experiments the magnetic poles should be about 0*25 of 

 an inch apart. 



A burning piece of amadou, or the end of a splinter of wood, 

 produced the same effect. 



By means of a small spark and stream of smoke, I have even 

 rendered the power of an ordinary magnet, in affecting them, 

 evident. The magnet was a good one, and the poles were 

 close to each other and conical in form. 



Before leaving this description of the general phsenomenon 

 and proceeding to a consideration of the principles of mag- 

 netic action concei-ned in it, I may say that a single pole of 

 the magnet produces similar effects upon flame and smoke, 

 but that they are much less striking and observable. 



Thougli the effect be so manifest in a flame, it is not, at 

 first sight, evident what is the chief cause or causes of the 

 result. The heat of the flame is the most apparent and pro- 

 bable condition ; but there are other circumstances which may 

 be equally or more influential. Chemical action is going on 

 at the time : — solid matter, which is known to be diamagnetic, 

 exists in several of the flames used : and a great difference 

 exists between the matter of the flame and *the surrounding 

 air. Now any or all of these circumstances of temperature, 

 chemical action, solidity of part of the matter, and differential 

 composition in respect to the surrounding air, may concur in 

 producing or influencing the result. 



