756 



MR J. D. HAMILTON DICKSON ON 



Table VI. 



t'C. 



dE/dt. 



t'C. 



- 79-1 



dE/dt. 



52-5 



318-6 



223-0 



24-0 



291-4 



- 95-6 



213-8 



3-6 



272-6 



-109-3 



205-2 



- 23-5 



255-2 



- 123-5 



1956 



- 44-4 



242-8 



-133-3 



188-6 



- 64-5 



231-8 



- 145-4 



180-8 



The asymptote HGH 7 suggests that the Tait-line for copper does not go to tempera- 

 tures higher than 324° C. But it is to be remembered that the present investigation 



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A 



















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-9i 



10" 



-21 



w° 







ll 



w° 



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-poo 





























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wo 



































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800 



\ 

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> 



\ 

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Fig. 8. 



deals only with the recorded observations, and makes no claim for extrapolation ; indeed, 

 had the observations been carried to higher temperatures, even slight alterations of the 

 constants might (as we have seen for copper itself) considerably modify the Tait-line. 



Zinc. 

 Zinc was examined at an early stage in the investigation, and as the curve it gave 

 on plotting the observations was comparatively flat for its length, it was difficult, if the 

 curve were parabolic, to determine any slope of the axis. Later it was examined by 



