and Rock Densities at High Temperatures. 



11 



cent at 500°. The effect of errors in the expansion coefficient 

 upon the measured volume of the metals was therefore 

 extremely small. The effect of a similar error upon the 

 measured volume of minerals was even smaller, because only a 

 crucible or shell of graphite of small volume was employed. 



Fig. 3. 







































30 





ACHESON GRAPHITE 



MEAN COEFFICIENT 



OF LINEAR EXPANSION 



FROM O" 























































































g 













3 o--^ 























I.O 



X 







c 



*i-^~ 





























-— 



» 



































































TEMPERATURE 



5. Specific Volume of Metals Used. 



It is hardly worth while to record the large number of 

 observations made on silver, tin, lead, the eutectic of tin and 

 lead, and other lead-tin alloys. The data on silver and the alloys 

 are not complete, and as the values do not enter into the volumes 

 of any substances discussed in this paper, they will be reserved 

 for later publication. The experimental results on tin, lead, 

 and the lead-tin eutectic are plotted in figs. 4 and 5. These 

 include three series on tin (11, 26, and 28 October 1910), 

 three on lead (30 June 1911, 13 March 1912, 31 January 1913), 

 and one on the eutectic (16 June 1911). The eutectic contains 

 63 weight per cent of tin, 37 of lead.* 



The volumes and densities at round temperatures are sum- 

 marized in Table I. 



The curves of figs. 4 and 5 have been completed between 0° 

 and our lowest temperatures of measurement by inserting the 

 data of Yicentini and Omodei. In the case of lead their value 

 for the density at the melting point is apparently too low, and 

 we have put in Table I the value obtained by extrapolating 

 our own curve over the very short interval of 11° between our 

 measurements and the melting point. 



The volume curve for tin is very nearly a straight line from 



*Bomemann, Metallurgie, viii, 271-275, 1911. 



