UPON GASES AND LIQUIDS. 559 



Thus nitrous gas acts generally in the same manner as the 

 vapour of iodine and bromine and chlorine gas. 



12. The experiment described in the preceding paragraph 

 especially claims our attention, because nitrous gas contains the 

 same ingredients as the air, but in ditferent proportions and in 

 a state of condensation. If the gas were merely condensed air, 

 its repulsion in the ordinary atmosphere would incontestably 

 prove that both the air and the gas are diamagnetic ; for con- 

 densed air, whether magnetic or diamagnetic, is necessarily more 

 powerfully affected by the magnet than that in the ordinary 

 state ; and from the repulsion of the former it would follow that 

 the action upon the air is altogether diamagnetic. [For exactly 

 the same reason, a more dense stone, which contains more mat- 

 ter, sinks in water ; whilst it would rise if the attraction of the 

 earth were to be converted into a repulsive force. Because the 

 force of gravity acts equally upon the matter of the stone and of 

 the water, we conclude, from the sinking of the former, that the 

 force of gravity exerts an attractive and not a repulsive power.] 



According to a general principle which Faraday (in the case 

 of solids and liquids) has laid down, every mechanical or che- 

 mical combination of diamagnetic bodies only is necessarily 

 diamagnetic, whilst every compound of magnetic bodies only 

 is magnetic. On extending this principle to gaseous bodies, the 

 experiment in the preceding paragraph would rigidly demonstrate 

 that, if nitrogen gas and oxygen are affected in the same manner 

 by the magnet, the action of both, as also the action of the 

 air and of the nitrous gas, must be diamagnetic. But if the air 

 exerted a magnetic action, one of the gases, either the oxygen 

 or the nitrogen, in fact that which predominates in nitrous gas 

 in comparison with the air, hence the first, must be diamagnetic, 

 the other magnetic. The latter supposition has not ^jer «e the 

 slightest probability ; on the other hand, we might admit 

 with more certainty that the air is diamagnetic, and we shall 

 adapt this view to our method of expression in the subsequent 

 remarks. 



13. Visible aqueous vapour, which must in fact be regarded as 

 nothing more than a true gas, is also repelled by the magnet. 

 It was evolved in a vessel used for the determination of the 

 boiling-point of water, and conducted by means of a long funnel 

 between the apices of the poles, the distance of which apart re- 

 mained the same as before. The repulsion was very distinctly 



