Yol. 65.] ANNIVERSARY ADDRESS OE THE PRESIDENT. CXI 



seated effects, such as the kaolinization of granite or the formation 

 of mineral lodes ; but over aDd above these are many secret processes 

 leading to the extrication of sodium, the nature of which must 

 always remain a matter for inference or speculation. This is 

 especially true in the case of Oceanic volcanos : within the heated 

 interior of these large quantities of sodium-bearing salts may be 

 liberated, and subsequently conveyed by one means or another into 

 the sea, without affording any outward signs of the fact. The 

 effect of these processes, however great, must, of course, remain for 

 all time beyond the reach of numerical estimates. Neither can 

 the contributions made by subterranean streams and submarine 

 action in general be expressed in figures : the irreducible minimum 

 eludes us, and all that we can assert is that the various estimates 

 of the age of the Ocean previously obtained are in excess to an 

 undetermined amount. These estimates are as follows : — 



(1) Judged from the total amount of sodium con- 



tained in some of the rivers of North 



America 47 millions of years. . 



(2) Do. do. do. of South America ... 101 „ „ 



(3) Do. do. do. of Europe 57 ,, ,, 



(4) From estimates 1, 2. 3 combined 77 „ ,, 



(5) From the total amount of sodium (exclusive of 



that combined with chlorine) in some of the 



rivers of North and South America 175 ,, ,, 



(6) From the silicic acid of some of the rivers of 



North and South America 421 „ ,, 



The last of these estimates is unquestionably too high : it is an 

 impossible maximum, rather illustrating the power of organisms to 

 remove silica from solution than affording a measure of geological 

 time. 



The last but one again is almost certainly too high. It is difficult 

 to be quite certain on this pointy because some of the sodium on 

 which the estimate depends is supplied from ancient deposits. On 

 the other hand, there can be no question that some of the sodium 

 which was excluded from consideration should come into the 

 account, for some sodium-chloride is supplied by juvenile waters ; 

 further, no allowance has been made for a number of factors which, 

 though important, cannot be estimated numerically. 



The fourth estimate is probably too low, some of the sodium on 

 which it depends having been derived from organic contamination 

 and rain-water ; possibly that supplied by marine action and 

 volcanos is sufficient to compensate for this ; on this point we 

 have no certain information. 



