1891. J President's Address. 229 



posed investigation. Let us hope that the alliance between the 

 London County Council and the Royal Society, for this great work, 

 may be successful in bringing out practically useful results. 



The President then presented the Medals awarded by the Society, 

 as follows : 



Professor Stanislao Cannizzaro (Copley Medal}. 



Stanislao Cannizzaro, Senator of Italy, and Professor of Chemistry 

 in the University of Rome, has rendered invaluable service to the 

 philosophy of modern chemical science. The work of Avogadro, in 

 1811, and afterwards that of Ampere, had already thrown much light 

 on the relative weights of the molecules of elementary bodies, and on 

 the proportions in which those weights enter into chemical combina- 

 tion. But it is to Cannizzaro that we owe the completion of what 

 they had left unfinished. He pointed out the all-important difference, 

 hitherto overlooked, between molecular and atomic weights, and 

 showed (1) How the atomic weights of the elements contained in a 

 volatile compound can be deduced from the molecular weights of 

 such compounds ; (2) how the atomic weights of the elements the 

 vapour-densities of whose compounds were unknown can be ascer- 

 tained by help of their specific heats. By these investigations the 

 series of atomic weights of the elements, the most important of all 

 chemical constants, and the relation which these weights bear to the 

 molecular weights of the elements, have been placed on the firm basis 

 on which they have ever since rested. It is to Cannizzaro that 

 science is indebted for this fundamental discovery, and it is this 

 which it is proposed to recognise by the award of the Copley Medal. 



Professor Charles LapivortJi, F.E.S, (Royal Medal). 



Professor Lapworth is the author of some of the most original and 

 suggestive papers which have appeared in the geological literature of 

 this country for the last twenty years. Special reference may be 

 made to his researches on graptolites, and to his patient investigation 

 by these means of the exceedingly complicated structure of the 

 Silurian uplands of the South of Scotland. He has been able not 

 only to supply the key which has given the solution of the strati- 

 graphical difficulties of. that region, but also to furnish theoretical 

 geology with an array of new facts from which to philosophise as to 

 the mechanism of mountain-making. Of not less importance are his 

 detailed studies of the structure of the North-west Highlands and his 

 demonstration of the true order of stratigraphical sequence in that 

 region of complex disturbance. As a stratigraphist he has attained 

 the highest rank, and he has likewise made himself a chief paleeonto- 



VOL. L. R 



