262 



Messrs. V. Harcourt and Esson on the [Nov. 22, 



November 22, 1866. 



Lieut. -General SABINE, President, in the Chair. 



In accordance with the Statutes, notice was given from the Chair of the 

 ensuing Anniversary Meeting, and the list of Council and Officers nominated 

 for election was read as follows : — 



President. — Lieut.-General Edward Sabine, R.A., D.C.L., LL.D. 

 Treasurer,— ■Willmm Allen Miller, M.D., LL.D. 



_ I Wilham Sharpey, M.D., LL.D. 

 ^secretaries.— | ^^^^^^ Q^hiiel Stokes, Esq., M.A., D.C.L., LL.D. 



Foreign Secretary. — Professor William Hallows Miller, M.A., LL.D. 



Other Members of the Council. — Lionel Smith Beale, Esq., M.B. ; "Wil- 

 liam Bowman, Esq. ; Commander F. J. Owen Evans, B.N. ; Edward Frank- 

 land, Esq., Ph.D. ; John Hall Gladstone, Esq., Ph.D. ; William Robert 

 Grove, Esq., M.A., Q.C. ; William Huggins, Esq. ; Thomas Henry Huxley, 

 Esq., LL.D. ; William Lassell, Esq. ; Professor Andrew Crombie Ramsay, 

 LL.D. ; Colonel William James Smythe, R.A. ; William Spottiswoodej 

 Esq., M.A.; Thomas Thomson, M.D. ; William Tite, Esq.; Vice-Chancellor 

 Sir W. P. Wood, D.C.L. ; The Lord Wrottesley, M.A., D.C.L. 



The following communications were read : — 



I. " On the Laws of Connexion between the conditions of a Che- 

 mical Change and its Amount.^' No. II. " On the Reac- 

 tion of Hydric Peroxide and Hydric lodide.^^ By A. Vernon 

 Harcourt^, M.A._, and W. Esson^ M.A. Coinmunicated by 

 Sir Benjamin Collins Brodie, Bart. Received July 13, 

 ■ 1866. 



(Abstract.) 



In a former paper, of which an abstract appeared in the Royal Society's 

 Proceedings, vol. xiv. p. 470, the authors gave an account of their first 

 experiments on this subject. 



The second chemical change chosen for investigation was that which 

 occurs in a solution containing hydric iodide (hydriodic acid) and hydric 

 peroxide. In this case the amount of change stands in relation to the 

 following conditions, — (I) the nature of the solution, that is to say, its 

 temperature, and the nature and quantity of the different ingredients which 

 it contains in a unit of volume, (2) the quantity of the solution, or the 

 number of such units of volume, (3) the time during which the change 

 proceeds. The relation of the amount of change to the second and third 

 of these conditions is determinate : it varies directly with each ; for the 

 solution is homogeneous, and, if all other conditions are fixed, the rate of 

 change is uniform. But the first condition comprises an almost indefinite 

 number of particular conditions ; for not only may various iodides and per- 



