302 Mr. T. E. Thorpe on the [Feb. 17, 



as expressing the expansion of iodine monochloride between 0° and its 

 boiling-point : — 



V=l + 0'000 915 896 6t + -000 000 832 957 6 f 



+ 000 000 002 750 05 f, 



by means of which the following Table has been calculated : — 



°c. 



Volume. 



Diff. 



°0. 



Volume. 



Diff. 







100000 





55 



105335 



513 



5 



100460 



460 



60 



105855 



520 



10 



100925 



465 



65 



106381 



526 



15 



101394 



469 



70 



106914 



533 



20 



101867 



473 



75 



107454 



540 



25 



102346 



479 



80 



108001 



547 



30 



102830 



484 



85 



108556 



555 



35 



103320 



490 



90 



109118 



562 



40 



103815 



495 



100 







45 



104315 



500 









50 



104822 



507 



101-3 



1-104187 





The specific gravity at 101-3 is 2*88196 ; hence the specific volume of 

 iodine monochloride == q-sriqb = 56*319. 



In the paper already referred to, Mr. Hannay has given the results of 

 a number of observations on the specific gravity of this compound at 

 various temperatures. I am unable to compare his numbers with my 

 own, as the temperatures to which his specific gravities are referred 

 are not given • but the conclusion which Mr. Hannay draws from his 

 observations, " that iodine monochloride expands equally for equal in- 

 crements of temperature, even near its boiling-point," is obviously 

 erroneous. 



III. Ethene Dibromide, C 2 H 4 Br 2 . 



This compound was prepared from well-washed ethene and bromine 

 by means of the arrangement described by Hofmann. The product, 

 after having been dried by phosphorus pentoxide, boiled completely be- 

 tween 130°-1 and 130 o, 8, the greater portion coming over between 

 130°*6 and 130°*7; n=55°, *' = 110°. Barometer corrected and reduced 

 766*6 millims. Corrected and reduced boiling-point 131°*36, In air- 

 thermometer degrees 131°*45. 



The statements on record respecting the solidifying-point of this 

 compound are extremely discordant; they vary from —12° or —15° to 

 + 13°*1. By careful trial I found that ethene dibromide solidifies at 

 + 9°*2, which is almost identical with the number given by Eegnault, 

 viz. 9°*53. 



The specific gravity of ethene dibromide is 2-19011 at 10 o, 89, com- 



