374 BURGESS AND WALTENBERG : MELTING POINTS 



TABLE I 



Melting Point of Iron in Hydrogen by Micropyrometer 



Electrolytic, C. F. Burgess 1538°, 1537°, 1530°, 1534°, 1530°, 1532° 



Mean 1533° 



Electrolytic, Langheim-Pfanhauser 1524°, 1532°, 1534°,. 1534°, 1535° 



Mean 1532° 



Electrolytic, Cain 1533° 



Powder, "Kahlbaum" 1534° 



From Oxide, "Kahlbaum" 1532 



o 



The mean value is 1533° ±1°. This is somewhat higher than 

 all other recent determinations, which range from 1502° to 1532°. 

 In the Arsem furnace, we obtained in vacuo 1531°, 1529°, 1531°, 

 1527°, and in hydrogen 1523° and 1527°. 



Cobalt. The cobalt used was cobalt ''Kahlbaum" in the form 

 of powder, Kahlbaum's Wiirfeln, cobalt reduced in hydrogen on 

 the platinum strip from ''Kahlbaum" cobalt oxide, and a sample 

 kindly furnished by Messrs. Day and Sosman, cut from material 

 which had been used for their determinations and which was 

 originally powdered cobalt "Kahlbaum,"^ shown by Dr. E. T. 

 Allen to be 99.951 per cent cobalt. The mean is 1477° ± 2. 



TABLE II 

 Melting Point of Cobalt by Micropyrometer 



(( 



Kahlbaum," powder and Wtirfel together; 1478°, 1479°, 1482°, 1476°, 1475°, 



1476°, 1478° 



Mean 1478° 



Co from the oxide "Kahlbaum" 1475°, 1478° 



Day and Sosman's sample 1474°, 1478°, 1478 



o 



Three observations taken in the Arsem furnace each gave for the 

 melting point of cobalt 1478°. Finally two melts of cobalt on 

 iridium gave with the micropyrometer 1477° and 1478°. The 

 value of the cobalt point which Day and Sosman found is 1490° 

 in a nitrogen atmosphere. 



Chromium. Strictly pure chromium was not available, and it 

 is difficult to locate exactly the melting points of an impure vis- 

 cous substance. Observations were taken on two samples from 



* Day, Sosman and Allen, 1. c. 



