306 



Mr. T. E. Thorpe on the 



[Feb. 17, 



iodide between 0° and its boiling-point. The following Table gives the 

 true volume of this liquid for every 5° between these intervals : — 



°c. 



Volume. 



Diff. 



°0. 



Yolume. 



Diff. 







100000 





85 



108541 



549 



5 



100470 



470 



90 



109097 



556 



10 



100942 



472 



95 



109661 



564 



15 



101416 



474 



100 



110234 



573 



20 



101894 



478 



105 



110816 



582 



25 



102375 



481 



110 



111408 



592 



30 



102860 



485 



115 



112009 



601 



35 



103349 



489 



120 



112619 



610 



40 



103843 



494 



125 



113239 



620 



45 



104341 



498 



130 



113871 



632 



50 



104845 



504 



135 



114513 



642 



55 



105354 



509 



140 



115166 



653 



60 



105868 



514 



145 



115830 



664 



65 



106389 



521 









70 

 75 



106916 

 107450 



527 

 534 



140-1 



1-15179 





80 



107992 



542 









The specific gravity of ethene chloriodide at its boiling-point is 1*87915 • 



and its specific volume = ■ ^^^ = 101-27. 

 r 1-87915 



It is evident from these observations that the specific volumes of 



bromine and iodine chloride are not equal, neither are the specific 



volumes of ethene bromide and ethene chloriodide • the bodies with the 



greater molecular weights have the greater specific volumes. 



Molecular weight. Specific volume. 



Bromine 159*90 " 53-62 



Iodine chloride 162-31 56-32. 



Ethene bromide 187'90 97'30 



Ethene chloriodide 190*31 101*27 



The number obtained for iodine monochloride differs considerably from 

 the volume calculated by means of Kopp's values (CI = 22-8, 1=37*5), 

 viz. 60*3. The specific volume of bromine (Br 2 ) is also less than Kopp's 

 number, 55*6. The value assigned to chlorine is unquestionably far 

 more accurate than that given to iodine, since the value of the latter 

 element was calculated from only two or three compounds, whereas the 

 former value was deduced from a comparatively large number of 

 chlorinated products. That the value for iodine needs revision seems to 



