THE LINEAR COMPRESSIBILITY OF COPPER AND IRON, ETC. 



megabars, or 0.00000383 expressed in atmospheres) may be accepted as 

 the most probable value, because it depends upon actual measurements 

 alone. Nevertheless it is clear that with more elaborate apparatus and 

 by the expenditure of more time, better results might be obtained in the 

 same way. Hence these results are to be considered merely as prelim- 

 inary ones, worthy of publication because they exemplify the working of 

 an efficient arrangement of apparatus, as well as because they confirm 

 essentially the work of others on this subject. The present results appear 

 to be accurate enough to serve the present purpose, therefore the execution 

 of the yet more precise determinations is left for the future, when the need 

 for them may arise. 



In this work, as well as in the preceding and following investigations, 

 the support of the Carnegie Institution of Washington was of great assist- 

 ance, and the authors express their thanks. 



SUMMARY. 



The method of Richards and Stull was used for determining the differ- 

 ences between the compressibilities of copper, iron, and mercury. The 

 determination of the linear compressibilities of rods of copper and iron 

 nearly 3 meters long, then, afforded two independent means of calculating 

 the cubic compressibility of mercury. The results for the cubic compress- 

 ibilities of the three metals are given in the following table, expressed in 

 terms of the three standards of pressure commonly in use : 



Cubic compressibilities of copper, iron, and mercury 

 between 100 and 500 atmospheres. 



