BURGESS AND WALTENBERG : MELTING POINTS 



377 



no signs of melting on platinum ; their melting points were taken 

 on iridium strips. 



TABLE VI 

 Melting Point of Titanium by Micropyrometer 



Ti From Professor Hunter 1790°, 1785°, 1785° 



Mean 1788° 



Ti From Dr. v. Wartenberg 1778°, 1807,° 1815° 



Mean 1800° 



These melting points are fairly sharp, and the location of the 

 temperature was made by calibrating the micropyrometer for the 

 iridium strip by taking observations on it of the melting of pal- 

 ladium (1549°), and of platinum (1755°). 



Summary. We have shown that the mipropyrometer may be 

 made an instrument of precision for the determination of the 

 melting points of refractory metals and salts ; that in the case of 

 the metals examined, the effect of alloying of microscopic particles 

 on platinum and iridium is inconsequential until after melting 

 which we have shown for nickel, cobalt and iron to occur at the 



TABLE VII 

 Melting Points of Elements of Atomic Weight 48 to 59 



* Assumed value on platinum strip; also observed value on iridium strip. 

 t Crucible melts in electric furnace. 



t Crucible melts in electric furnace; also on iridium strip "with micropy- 

 rometer. 



§ Five samples all agreeing to within 3°. 



