

110 





2% 



a?w/ AZta 



i— Isomorphism and Thermal 











abian 2 . 













First Preparation. 













E. M. F. Temper- 







Date 





Element. 



in MV. atnre. 



Kemarks. 



Oct. 



16, 



1903 



A 



14895 1459° 



rapid heating. 



a 



u 



a 



No. 3 



15142 1460 



slow " 



a 



21 



a 



3 



15101 1457 



rapid " 



a 



a 



a 



3 



152 20 1466 



extremely slow 



heating. 



a 



22 



a 



3 



15204 1465 



rapid heating. 



u 



a 



a 



3 



15160 1462 





Dec. 



15 



a 



3 



15116 1467 



powdered charge, 

 open crucible. 



u 



u 



i( 



3 



15103 1466 



ditto, slower. 



a 



16 



" 



3 



15109 1467 



solid cake, covered. 



(C 



a 



£C 



3 



15044 1462 



very fast. 



a 



a 





3 



15040 1462 



same slower. 



a 



c< 



a 



A 



15035 1467 







Mean 1463° 













Second Preparation. 





Feb. 



19, 



1904 



A 



14945 1460° 



covered, slow. 



a 



20 



a 



No. 3 



15096 1466 



ditto, faster. 



a 



25 



a 



2 



15239 1467 



fast. 



Mean 1464° 



Melting temperature 1463°. 



Here again we made an attempt to discover a possible dif- 

 ference in composition in the first portions to crystallize out of 

 the melt, this time by optical means. We first cooled the 

 charge so rapidly that only a relatively small portion crystal- 

 lized out in fine, reddish-brown spherulites at the surface and 

 near the wall of the crucible. Without disturbing these, the 

 crucible was then replaced in the furnace and slowly reheated 

 until (about 5 hours) the remaining vitreous material had also 

 become completely crystallized. Upon removing from the fur- 

 nace, the charge presented a singular appearance. The reddish- 

 brown stars remained undisturbed, while the later crystals were 

 perfectly white. But though so different in appearance, the 

 microscopic examination of slides cut from the different por- 

 tions showed the two to be optically identical. 



We have here another instance of the tendency of the iron 

 to concentrate in the crystals which first form, a tendency 

 which was frequently noticed, throughout our work. It also 

 appeared to matter little whether the first crystals formed at 

 the surface or at the bottom of the charge. It is possible that 

 this phenomenon may have significance in ore deposition, but 

 we have not thus far been able to give it adequate attention. 



