Kinetic Theory of Solids. 



37 



of knowledge on this subject are Kohlrausch and Loomis 

 (Pogg. Ann. cxli.), Napiersky (Pogg. Ann., Erganzbd. iii.), 

 and Tonilinson (Proc. Poy. Soc. xl.), who do not go beyond 

 100°. The simplest way of comparing the results of different 

 experimenters will be to tabulate the ratio of the rigidity at 

 100° to that at zero as found by each, I will also give from 

 Pisati the ratio for rigidity at 200°. Where a specimen is 

 known to have been unannealed it will be marked (u.) 



Table I. 



Metal. 



Copper (u) 

 Copper 



Silver (it) 

 Silver 



Gold 00 .. 

 Magnesium 

 Zinc 



Aluminium (//). 



Tin 



Lead 



Iron 



Nickel 



Platinum (u) 

 Platinum .... 



100°. 



•969 

 •971 

 •945 

 •971 

 •960 

 •956 

 •962 

 •961 

 •971 

 •943 

 •843 

 •749 

 •932 

 •943 

 •638 

 •773 

 •979 

 •960 

 •950 

 •973 

 •974 

 •984 

 •982 

 •993 



200 : 



•911 

 •917 



•858 

 •898 



•912 



•803 



•942 



•964 

 •934 



Authority. 



Pisati. 



Pisati. 



Kohlrausch. 



Tomlinson. 



Pisati. 



Pisati. 



xSapiersky. 



Tomlinson. 



Pisati. 



Sutherland. 



Tomlinson. 



Sutherland. 



Pisati. 



Tomlinson. 



Sutherland. 



Sutherland. 



Pisati. 



Napiersky. 



Kohlrausch nnd Loomis. 



Tomlinson. 



Tomlinson. 



Pisati. 



Pisati. 



Tomlinson. 



The discrepancies in the above table are such as have 

 hitherto proved inevitable in elastic experiments on account 

 of differences in purity of specimen and elastic state. But in 

 Pisati's experiments up to 200 for the metals with high 

 melting-point, and in my own up to 100° for those with low 

 melting-point, there is a large enough variation of rigidity to 

 be only slightly perturbed by accidental circumstances, as will 

 be seen when the law of variation is under discussion. In the 

 case of zinc, where there is pronounced disagreement between 

 Tomlinson' s result and my own, Tomlinson's is to be preferred 

 as he experimented on a true wire. 



