258 Prof. Liveing, On the dispersion [May 19, 



It seems perfectly clear that there are and always have been 

 earth movements going on which have perpetually unsettled the 

 condition affecting life, and that these movements are slow and 

 more or less regular in their action. 



The sequence of life upon the earth, showing a gradual in- 

 coming of new or modified forms all through, and not- a succession 

 of total extinctions and replenishments, points to the persistence 

 of oceanic and continental areas, as an interruption in the con- 

 tinuity of suitable land and climate or of water of the required 

 temperature, salinity or depth, would be destructive to life. 

 Therefore the movement must have been of the nature of an 

 earth-wave, the land rising on one side and sinking on the other of 

 a given area. 



Stratigraphical evidence shows that the submergence which 

 allowed of the accumulation of sediment often commenced earlier 

 over one part of the area than another, and that the direction of 

 the movement of such troughs was not always the same. The 

 foregoing palseontological considerations confirm this. Only some 

 forms of life succeed in migrating because some directions are 

 more fatal than others, namely, those which necessitate travelling 

 across greater extremes of conditions affecting life. 



It is only reasoning in a circle to define formations palseonto- 

 logically and then to speak of the incoming and outgoing of 

 species as nearly coincident with the beginning and end of the 

 formation, but as denudation and deposition are necessarily equal, 

 and no denudation can take place until the solid matter of the 

 earth's crust has been lifted up within reach of the denuding 

 agents, the periods of these earth-waves must somewhat coincide 

 with the periods of deposition and denudation as given in the 

 accompanying table, and these form our geological measures 

 of time. 



Whether the transference of the immense masses of denuded 

 material always to the coastline of continents is the cause or 

 effect, or modifies the direction of the earth-waves, is a question 

 as yet unanswered. 



Monday, May 19, 1879. 

 Professor G. D. Liveing, President, in the Chair. 



The following communications were made to the -Society : — 

 (1) Professor Liveing, On the dispersion of a solution of mer- 



curic 



iodide. 



In the Chemical Neius, vol. 29, p. 128, Mr E. Sonstadt proposes 

 the use of a solution of mercuric iodide combined with potassium 



