186 BRIDGMAN. 



has been found by Richards to be 5.2 X 10~ 7 . His material was from 

 the General Electric Company, and was in the form of fused buttons. 



Palladium. Runs were made on two different samples, both of 

 which I owe to the kindness of Baker and Company. They were said 

 to be of the highest attainable purity, but I have no analysis. One of 

 these was a massive specimen, 0.75 cm. in diameter and 2.5 cm. long. 

 It was used as a compression specimen in the lever apparatus for short 

 specimens. The second was in the form of wire, 0.062 cm. in diameter, 

 10 cm. long, and was mounted as a tension specimen in the lever 

 apparatus for long specimens. Each sample was annealed after 

 receiving from Baker, the massive specimen by heating to 800° for 

 two hours in an electric furnace and slowly cooling, and the wire by 

 heating in a Bunsen burner to a bright red. Two regular runs, at 

 30° and 75°, were made on each specimen. 



The average arithmetical departure of the readings of the massive 

 specimen from a smooth curve (no discards) was 2.2% of the maxi- 

 mum pressure effect. It was not possible to detect any departure 

 from linearity. For the wire the average arithmetical departure was 

 3.0% of the maximum pressure effect, and again there was no detecti- 

 ble departure from linearity. The final results found for these two 

 specimens are: 



AV 

 Massive specimen, At 30° — = - 10~ 7 (5.19 - 2.1 X KH p) p 



>o 



AV 



At 75° — = - 10- 7 (5.11 - 2.0 X KHp) p 

 I o 



Drawn wire, At 30° ^- = - 10- 7 (5.28 - 2.1 X 10" 5 p) p 



Jo 



At 75° — = - 10- 7 (5.31 - 2,1 X H)- 5 p) p. 

 Vo 



It is to be noticed that the temperature coefficient of the massive 

 palladium appears to be negative. This is a very unusual occurrence, 

 and it is to be doubted whether the accuracy of the measurements is 

 so high as to compel the conclusion that this is actually the case. 



The initial compressibility of palladium at 20° has been found by 

 Richards to be 5.3 X 10~ 7 , agreeing perfectly with the value found 

 above for the wire. Richards' material was also obtained from Baker, 

 and was a massive specimen weighing 94 gm. Its density was 12.14, 

 against 1 1 .97 for the massive specimen above. 



Nickel. Measurements were made on samples from two sources. 



