384 Mr. P. E. Chase on the Specific Magnetism of Iron. 



denude the globe as rapidly as the subaerial agents, it would 

 have to advance on the land at the rate of upwards of 17 feet 

 annually. 



[To be continued.] 



XLIV. On the Specific Magnetism of Iron. 

 By Pliny Earle Chase*. 



IN my communication on the numerical relations of gravity 

 and magnetism f, after adducing various evidences of a cor- 

 relation that had been long suspected, I endeavoured to obtain 

 approximate valuations for the constant factor K, which was in- 

 troduced in the comparison of the tidal forces with the force of 

 equilibrium. These approximations led me to " suggest the pro- 

 priety of considering the element of density (or of its correlative, 

 the square of the time of molecular diffusion), in connexion with 

 both A and M." 



In the year after this suggestion was made, Dr. Menzzer an- 

 nounced, as an experimental result (Poggendorff's Annalen, No- 

 vember 1865; Phil. Mag. vol. xxx. p. 456), that "themagneti- 

 zing-powers of two coils which give the maximum of intensity 

 are as the square roots of their weights." 



It therefore appears, 



(1) From Graham's and other well-known laws : — 



Elasticity oc specific heat oc (wave velocity) 2 . 

 Density oc (time of molecular diffusion) 2 . 

 "Weight oc (time of sonorous vibration) 2 . 



(2) From observations on terrestrial magnetism : — 



Tidal differences oc (magnetic differences) 2 . 

 Magnetic variation oc (time) 2 . 



(3) From Menzzer's experiments : — 



Weight oc (magnetizing-power) 2 . . . 



This indirect confirmation of a conjecture which was at first 

 based on a plausible analogy, encourages me to hope that the 

 following comparisons between molecular and cosmical kinetic 

 values may help to explain the specific magnetism of iron. 



According to Tredgold, iron may be elongated about y^-^- 

 without permanent alteration of structure. Now the ratio, at 

 the earth's surface, of solar terrestrial attraction is about xeVcr > 

 and four times the ratio of the specific gravity of air to that of 

 iron varies approximately between 14 1 00 and ttVo* Although 

 this range of variation is somewhat more than £ of the least 



* From Silliman's American Journal for March 1868. 



f Trans. Amer. Phil. Soc. vol. xiii. p. 126. [Phil. Mag. July 1865, p. 52.] 



