Phil. Mag. Ser. 6, Vol. 6, PI. XL 



Diagram 4. 



1-35 



1-30 



l-2i; 



Diagram 6. 





1-45 



1-40 



1-35 



1-30 



1-25 



1-20 



1-li 



N . o 



o 



1100 1200 1300 1400 1500 



Temperatures Centigrade. 



Fig. 2. 



