Mr, J, Ball on the Veined Structure of Glaciers. 263 



like the iodine compound, for each equivalent of arsenic three 

 equivalents of v\ater, only half of which, or 9-55 per cent., is 

 removed by exposure over oil of vitriol. On exposui-e to heat in 

 a water-bath, water is first evolved, then a little hydrobromic 

 acid, and subsequently bromide of arsenic : the whole of the 

 bromine is expelled by continued exposure to the temperature of 

 the water-bath. Analysis gave — 



Arsenic 



Bromine .... 13*70 



Oxygen 



Water .... 16-54 



576 100-00 



AsBr02,8As03 + 12HO, or AsBi'3 + llAs03 + 12H0. 



When a concentrated cold solution of bromide of arsenic is 

 treated with bromide of ammonium, well-formed sLx-sided tables 

 with bevelled edges are slowly formed. These consist of anhy- 

 drous bromide of arsenic, with a small proportion of bromide of 

 ammonium mechanically mixed with it. Deducting 9-24 per 

 cent, of bromide of ammonium, analysis gave — ^ 



Ai-senic ... 1 = 75 23-81 



Bromine. . 76-40 75-75 3 = 240 76-19 



315 100-00 



Bromo-arsenious acid does not appear to form compounds with 

 the alkaline bromides. 



XLI. Remarks on the Veined Structure of Glaciers, 

 By John Ball, M.R.I.A., F.L.S* 



PROFESSOR TYNDALL having done me the honour to 

 refer, in his recent lecture upon glacier structure at the 

 Royal Institution, to an article which I contributed to this 

 jom-nal in December 1857, and having intimated that it had the 

 fortunate result of inducing him to examine, still more closely 

 than before, some of the phaenomena of glaciers, I trust I may be 

 pci-mittcd to offer a few remarks upon the present state of the 

 question which has been in debate — the origin of the veined 

 structure in glacier ice. 



1 must commence by avowing my conviction that, substan- 

 tially. Professor Tyndall has been victorious over those, myself 

 included, who were at first disposed to doubt his theory, that 

 pressure is the efficient cause to which the veined structure 

 generally, if not universally, owes its origin. This victory has 



* Commuiiicated by the Author, 



