certain High-temperature Boiling-points, 



145 



usually fractured by the cone of solidified metal k k on heating 

 a second time. Any single ebullition, however, may be 



Fig. 2. — Longitudinal section of boiling-point crucible. 



Scale £. 



prolonged almost indefinitely, that is half a day or more. I 

 found no serious difficulty in obtaining vacua of two or three 



