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Article XIX. 



On the Determination of the Intensity of Magnetic and Diamag- 

 netic Forces. By Professor Plucker of Bonn^. 



[From Poggendorff's Annalen for July 1848.] 



§ 1. General Considerations. 



] . 13 Y the intensity of the magnetism of a substance, I understand 

 the intensity of that force with which this substance, when near 

 one of the poles, is attracted by it in consequence of magnetic 

 induction. We must first establish some point of view, in which 

 we may compare this magnetism, which is specifically dependent 

 upon the nature of the substance, as it occurs in the case of dif- 

 ferent substances. In so doing, by commencing with any one 

 substance, its intensities may then be expressed by absolute 

 numbers, as has been done for instance with specific heat. 



2. If we take a watch-glass and grind its margin to fit a flat 

 glass plate so that the latter accurately closes it, we may fill it 

 with a liquid above the margin, and then skim this oflf with the 

 flat glass forming the cover. We are then certain that any in- 

 closed liquid having the same form occupies exactly the same 

 volume. If we fill the watch-glass with two different fluids 

 successively, and if this is then equally attracted by the pole of 

 a magnet, to which it is in each case exposed in a similar man- 

 ner, both fluids are in the same degree magnetic. If the attrac- 

 tion of the two fluids is at all different, we consider the intensity 

 of their magnetism as proportional to this attraction. The proof 

 of this will be theoretically and experimentally given in the next 

 paragraphs. 



3. If for instance the two fluids are solutions of different iron 

 compounds, and if equal volumes of each contain the same num- 

 ber of atoms of iron, in both cases these atoms are distributed in 

 the same manner within the watch-glass, and have exactly the 

 same position as regards the pole of the magnet ; the proportion 

 of the attraction of the whole volumes of the liquid may then be 

 regarded as the proportion of the magnetism of the atom of iron 

 in both the chemical compounds. For when two extremely 



• Translated by Dr. J. W. Griffith. 



