92 



Prof. G. Quincke on the Constants of 



11. If we treat bromine with pure hydrated sulphuric acid in 

 order to have it perfectly free from water, and if we then allow 

 it to drop in the way described above, the numbers which we 

 obtain in this way for the constants of capillarity nearly agree 

 with those determined by Bede*, who found « 2 = 2*51 square 

 millims. to 2*81 square millims. for 6°"8 C. 



Bromine (cr=3-18). 



2r. 



W. 



as. 



2* 



a= — . 



millim. 

 0-8407 

 0-6998 

 0-4934 



grm. 

 00088 

 000744 

 0-0053 

 Temp. : 



mgrms. 



3-335 



3-385 



3-420 



= 13° C. 



sq. millims. 

 2-097 

 2- 128 

 2151 



The observation of the elevation h in capillary tubes of radiui 

 r for the same substance gave 



Bromine. 



2r. 



h. 



a?=hr. 



millim. 

 0-4635 

 0-2079 



millims. 



11-7 



28-3 



Temp.=:13 C 



millims. 

 2-712 

 2-943 



These numbers agree, all of them, very closely with the deter- 

 minations by Bede. 



1 suspected, however, that the capillarity-constants of bro- 

 mine altered rapidly with the temperature, and I attempted ac- 

 cordingly to make a determination in the neighbourhood of the 

 freezing-point. A rather wide test-tube, which contained bro- 

 mine and a glass tube divided into millimetres, of \208 millim. 

 diameter, was set obliquely in a mixture of salt and snow, so 

 that the bromine solidified. The glass tube was then brought 

 out of the freezing-mixture into the usual temperature and set 

 vertical. When the bromine was thawed, it showed an elevation 

 of 37'5 millims., from which we deduce 



a 2 — 3*895 sq. millims., a = 6'328 milligrms. 



for the melting-point of bromine. 



Determinations of this sort are made much more easily in 

 winter. 



* Mem. Cour. et des Savants etravgers de V Academe de Belgique, vol. xxx. 

 (1860) p. 163. 



