of Flame and Gases, 415 



stand, made a very good chamber about them. The pipe to 

 supply and change the gaseous medium, and also that for 

 bringing the gas under trial as a stream into the magnetic 

 field, passed through holes made in the bottom of the stand. 

 The different gases to be compared with those employed as 

 media, were, except in the cases of ammonia and chlorine, 

 mingled with a trace of muriatic acid, as before described. 

 The gaseous media used were two, coal-gas and hydrogen. 

 Whilst using coal-gas, I observed the direction of the currents 

 of the other gases in it by bringing a little piece of paper, at the 

 end of a wire and dipped in ammonia solution, near the stream. 

 In the case of the hydrogen, I diffused a little ammonia through 

 the whole of the gas in the first instance. 



Air passed towards the axial line in coal-gas, but was not 

 much affected. 



Oxygen had the appearance of being strongly magnetic in 

 coal-gas, passing with great impetuosity to the magnetic axis, 

 and clinging about it; and if much muriate of ammonia fume 

 were purposely formed at the time, it was carried by the oxygen 

 to the magnetic field with such force as to hide the ends of the 

 magnetic poles. If then the magnetic action were suspended 

 for a moment, this cloud descended by its gravity ; but being 

 quite below the poles, if the magnet were again rendered active, 

 the oxygen cloud immediately started up and took its former 

 place. The attraction of iron filings to a magnetic pole is not 

 more striking than the appearance presented by the oxygen 

 under these circumstances. 



Nitrogeji. — Clearly diamagnetic in coal-gas. 



Olefianti carhojiic oxide, and carbonic acid gases were all" 

 slightly, but more or less diamagnetic in the coal-gas. 



On substituting hydrogen as the surrounding medium in 

 place of coal-gas, more care was taken in the experiments. 

 Each gas experimented upon was tried in it twice at least ; 

 first in the hydrogen of a previous experiment, and then in a 

 new atmosphere of hydrogen. 



Air. — Air passes axially in hydrogen when there is very 

 little smoke in it: when there is much smoke in the stream 

 the latter is either indifferent or tends to pass equatorially. I 

 believe that air and hydrogen cannot be far from each other. 



Nitrogen is strikingly diamagnetic in hydrogen. 



Oxygen is as strikingly magnetic in relation to hydrogen. 

 It presented the appearances already described as occurring 

 in coal-gas; but as the jet delivered the descending stream 

 of oxygen a little on one side of the axial line, its centrifugal 

 power, in relation to the axial line, was so balanced by the 

 centripetal power produced by the magnetic action, that the 



