1879.] the Effect of Heat on the Di-iodide of Mercury. 



287 



The coefficient of cubical expansion for 1° C. from 126° C, after 

 the change to the melting point 200° C, was 



•0001002953. 



Tims, if we suppose a molten mass of the iodide of mercury to be 

 cooling down from 200° C. to 0° C, the following would be the 

 volumes under the conditions indicated : — 



Volume at 200° C. of the liquid mass = 1 1191147 



„ solid mass =1 -0190453 



126° C. (yellow prismatic condition) = 1 '0115378 

 ,, ,, (red octohedral condition) = 1 '0043337 



0° C =1 -ooooooo 



The changes are shown at one view in the accompanying curve 

 table, in which the expansion of mercury is given for comparison. 



• 20 • 40 . 60 • 80 • 100 • 12 



0° • IA0" • 160° . ISO' • 2C 



1 " 



o'C 



1-13 







1 





























— i 















1-12 

























































































Li 







141 





















1 























;] 







i 11 























































1 -1 

































































































z 







1-09 



















































* 























































I-C3 



















































• 



















































1-07 











































_ 











o 

























































_ 

































































































& 



1-05 

























L 













.' 

























Z 





























Z 



















i -n/L 

















_ 





















_ 





z 











* 

































, - - 



z 



j 







^ ■ 



__ 













__ 









■ 







































1-03 



.. 





















































_ 









_ 











_ 







■ i 







' j 





__ 

















_ 

















_ 







it 











: 

















So 



'la 





1-01 



















at i 



-ii'. 



r r> 





'til 





- . 









■ 















— 

 y 



^— 





_ 

 i 



_ 



6 









8 





i 





i: 



>0° 



ieif o 



• 140' 



— 



u 



Her 

 W 







2 



10* 



?7 



0* c 



According to Schiif the specific gravity of the octohedral iodide is 

 5-91 ; while Karsten makes it 6*2009, and Boullay 6*320. 



