WITH MAGNETISM AND ELECTRICITY. 



19: 



tained in this way, and merely remark that each determination 

 is the result of four changes of current in the spiral, the most 

 exact coincidence being in all cases exhibited, a proof that the 

 coercive force of the iron did not operate to the prejudice of the 

 measurements. The reduction, according to known rules, of 

 the magnetism oi" the iron to an absolute unit, requires no fur- 

 ther explanation. The strength of the current, measured by 

 means of a tangent galvanometer, is also reduced to an absolute 

 unit, and the correction depending upon the ratio of the length 

 of the needle to the diameter of the ring is taken into account. 

 From the strength of the current thus determined, the number 

 of convolutions and the dimensions of the spiral, the magnetizing 

 force operating upon the iron was finally calculated, in terms 

 of the same unit as that to which the terrestrial magnetic force 

 is referred ; it appears in the second column of the following table 

 under X. The magnetism of the iron M, divided by the mass 

 of the iron p =8190, and thus reduced to the unit of mass, is 

 exhibited in the third column under m. 



By these experiments the result obtained by Miiller is con- 

 firmed, and it only remains to ascertain whether the change in 

 the strength of the magnetism of the iron effected by the action 

 of different forces of magnetization, here exhibited, coincides 

 with the law deduced at the end of the first section, from the 

 assumption of a definite capacity of rotation on the part of the 

 molecules. If this be the case, it evidently follows that we can 

 assume, with Ampere, that these molecules are the bearers of 



SCI EN. MEM.— iVTa^ Phil. Vol. I. Paiit II. P 



