473 



The President announced that he had appointed the following 

 Members of the Council to be Vice-Presidents : 



The Treasurer. 



Sir Benjamin Collins Brodie, Bart. 



William Robert Grove, Esq. 



William Hopkins, Esq. 



James Paget, Esq. 



The following communications were read :- 



I. "On Crystallization and Liquefaction, as influenced by 

 Stresses tending to change of form in the Crystals." By 

 Professor JAMES THOMSON, Queen's College, Belfast. 

 Communicated by Professor WILLIAM THOMSON. Re- 

 ceived October 12, 1861. 



In a paper submitted to the Royal Society, and printed in the 

 'Proceedings* for April 25th, 1861,1 directed attention in a note 

 (page 201), to the question of how the surface of a bar of ice in ice- 

 cold water, as distinguished from the interior of the bar, may, bv the 

 application of tension to the bar, be influenced in respect to tendency 

 either to melt away, or to solidify to itself additional ice from the 

 water ; but did not then venture to offer a positive answer. I pointed 

 out as a matter deserving of special attention, and as affording scope 

 for much additional theoretical and experimental investigation, the 

 distinction between the application to ice in ice-cold water, of stresses 

 tending to change its form, the stresses not being participated in by 

 the water ; and the application directly to the water, and through 

 that to the ice, of cubical or hydrostatic pressures or tensions, these 

 being participated in by the water and the ice alike ; and I pointed 

 out that the theory and quantitative calculation which I had origi- 

 nally given* of the effect of pressure in lowering the freezing-point 

 of water, or of diminution of pressure in raising it, applied solely to 

 effects of pressure communicated to the ice through the water, and 

 therefore equal in all directions, and equally occurring in the ice and 

 the water ; but that when changes of pressure in one or more direc- 



* Transactions Roy. Soc. Edin. vol. xvi. part 5, 1849 ; and Cambridge and 

 Dublin Math. Journ. Nov. 1850. 



