420 On the Diamagnetic conditions of Flame and Gases. 



gases, but did not find it better than, or so good as, the one 

 1 have described. 



Such are the results I have obtained in verifying and ex- 

 tending the discovery made by P. Bancalari. I would have 

 pursued them much further, but my present state of health 

 will not permit it: I therefore send them to you with, probably, 

 many imperfections. It is now almost proved that many 

 gaseous bodies are diamagnetic in their relations, and probably 

 all will be found to be so. I say almost proved ; for it is not, 

 as yet, proved in fact. That many, and most, gaseous bodies 

 are subject to magnetic force is proved ; but the zero is not 

 yet distinguished. Now, until it is distinguished, we cannot 

 tell which gaseous bodies will rank as diamagnetic and which 

 as magnetic ; and, also, whether there may not be some 

 standing at zero. There is evidently no natural impossibility 

 to some gases or vapours being magnetic, or that some should 

 be neither magnetic nor diamagnetic. It is the province of 

 experiment to decide such points ; and the affirmative or ne- 

 gative may not be asserted before such proof is given, though 

 it may, very philosophically, be believed. 



For myself I have always believed that the zero was re- 

 presented by a vacuum, and that no body really stood with 

 it. But though I have only guarded myself from asserting 

 more than I knew, Zantedeschi (and 1 think also De la Rive), 

 with some others, seem to think that I have asserted the gases 

 are not subject to magnetic action ; whereas I only wished to 

 say that I could not find that they were, and perhaps were 

 not: I will therefore quote a few of my words from the Ex- 

 perimental Researches. Speaking of the preparation of a 

 liquid medium at zero, I say, "Thus a. Jluid medium was ob- 

 tained, which practically, as far as I could perceive, had every 

 magnetic character and effect of a gas, and even of a vacuum^ 

 &c." — Experimental Researches, 2423. Again, at (2433) I 

 say, "At one time I looked to air and gases as the bodies 

 which allowing attenuation of their substance without addition, 

 would permit of the observation of corresponding variations 

 in their magnetic properties, but now all such power by rare- 

 faction a/?/>^a;'5 to be taken away." And further down at(2435), 

 " Whether the negative results obtained by the use of gases 

 and vapours depend upon the smaller quantity of matter in a 

 given volume, or whether they are the direct consequences of 

 the altered physical condition of the substance, is a point of 

 very great importance to the theory of magnetism. I have 

 imagined in elucidation of the subject an experiment, &c., but 

 expect to find great difficulty in carrying it into execution, &c." 

 Happily P. Bancalari's discovery has now settled this matter 



