558 PLUCKER ON THE ACTION OF THE MAGNET 



of these two views, that both the iodine vapour and the air are 

 diamagnetic, is shown to be extremely probable by the experi- 

 ment detailed in paragraph 11. 



10. A few drops of bromine were placed in a glass retort with 

 a short neck, which was so drawn out that the aperture was not 

 more than 3 miUims. in diameter. The glass retort was then 

 arranged with its orifice immediately beneath the apices of the 

 poles, w hich were 3'5 millims. apart ; it was then heated, and 

 as soon as the vapour began to flow out the magnetism was ex- 

 cited. The ascending column of vapour was repelled in the 

 equatorial plane towards that side of the apices on which it 

 passed before the excitation of the magnetism, but not so con- 

 stantly and regularly as in the case of the iodine. Thus the 

 vapour of bromine acts in general in the same manner as that 

 of iodine. 



10 a. The vapour of chlorine, evolved from peroxide of man- 

 ganese, chloride of sodium and concentrated sulphuric acid, was 

 also repelled. 



11. In the same retort and with the same adjustment, pieces 

 of copper wire were placed, and nitric acid was then poured iipon 

 them ; the nitrous fumes which wei'e evolved escaped from the 

 orifice with a varying amount of force. That they were repelled 

 was at once perceptible ; but it was subsequently found, as the 

 vapour ascended in the form of a cylinder of about 4 millims. 

 directly between the poles, that they expanded above the apices 

 of the poles in the equatorial plane in the form of a parabola, the 

 summit of which was situated somewhat above the middle of the 

 space between the poles, and the axis of which was formed by 

 the continuation of the direction of the original gaseous current. 

 The latter, in the equatorial plane, retained nearly its original 

 diameter, but sloped off at right angles to this plane to about 

 one half. In the complete transverse section of the parabolic 

 current the gas appeared to be nearly uniformly diffused. It 

 ascended regularly to an elevation of from 60 millims. to 80 mil- 

 lims., although it was less distinctly defined than in the case of 

 the iodine. 



the poles of a magnet and allowed it to oscillate, when the tube was found to 

 become arranged axially or equatoriallj', hence reacting magnetically or dia- 

 niagnelically according as the internal or the external solution was the stronger, 

 may be easilj' repeated without any special precaution. P'or this purpose I 

 have used tubes of thin glass, 20 millims. in breadth and about 125 millims. in 

 length, closed with calves' bladder and without a keeper. 



