152 



Webster, Esq., M.A. ; Rev. William Whewell, D.D. ; Alex. William 

 Williamson, Ph.D. ; Rev. Robert Willis, M.A. ; Sir William Page 

 Wood, D.C.L. ; The Lord Wrottesley, M.A. ; Colonel Philip Yorke. 



Thomas Watson, M.D., Frederick Grace Calvert, Esq., John Penn, 

 Esq., and Lieut.-Col. William Yolland, R.E., were admitted into the 

 Society. 



The following communications were read : 



I. " On Recent Theories and Experiments regarding Ice at or 

 near its Melting-point." By Professor JAMES THOMSON, 

 Queen's College, Belfast. Communicated by Professor 

 WILLIAM THOMSON, F.R.S. Received September 9, 1859. 



My object in the following paper is to discuss briefly the bearings 

 of some of the leading theories of the plasticity and other properties 

 of ice at or near its melting-point, on speculations on the same sub- 

 ject advanced by myself*, and, especially, to offer an explanation of an 

 experiment made by Professor James D. Forbes, which to him and 

 others has seemed to militate against the theory proposed by me, but 

 which, in reality, I believe to be in perfect accordance with that theory. 



In the year 1850, Mr. Faraday f invited attention, in a scientific 

 point of view, to the fact that two pieces of moist ice, when placed in 

 contact, will unite together, even when the surrounding temperature 

 is such as to keep them in a thawing state. He attributed this pheno- 

 menon to a property which he supposed ice to possess, of tending to 

 solidify water in contact with it, and of tending more strongly to so- 

 lidify a film or a particle of water when the water has ice in contact 

 with it on both sides than when it has ice on only one side. 



In January 1857, Dr. Tyndall, in a paper (by himself and Mr. 

 Huxley) read before the Royal Society and in a lecture delivered 

 at the Royal Institution, adopted this fact as the basis of a theory 

 by which he proposed to explain the viscosity or plasticity of ice, 

 or its capability of undergoing change of form, which was pre- 



* Proceedings of Royal Society, May 1857. Also British Association Proceed- 

 ings, Dublin Meeting, 1857. Also Proceedings of Belfast Literary and Philoso- 

 phical Society, December 2, 1857. 



t Lecture by Mr. Faraday at the Royal Institution, June 7, 1850 ; and Report 

 of that Lecture, Athenaeum, 1850, p. 640. 



