558 W. Ach'oi/d — Circulation of Salt. 



5Hi Period. — Quaternary. Post-Glacial ; subsidence and partial 

 submergence of land ; retreat of the glaciers. Icebergs and rafts 

 of ice covering the adjoining sea. Amelioration of climate. 



6th Period. — Recent. Re-elevation to approximately present 

 position with regard to the outer ocean. Formation of raised 

 beaches (strand linien) during the progress of emergence. 



The paper concluded vpith a comparison between the above 

 physical features as they occur in Norway with those of Scotland. 



VII. — On tee C1RCULA.T10N OF Salt in its Eelations to Geology. 

 By William Ackrotd, F.I.C, F.C.S., Public Analyst for Halifax. 



A wrong impression is given by the question : " Why will 

 Mr. Ackroyd not have the 19 rivers ? " (Geol. Mag., 

 November, 1901, p. 505). The data collected by Sir John Murray 

 are admirable additions to our natui'al knowledge, and they are used 

 in my last article (Geol. Mag., October, 1901, p. 448), but I contend 

 that they are not available for use in the expression — 



Sodium in the sea. 



= the age of the Earth ; 



Sodium annually delivered into 



the sea by rivers. 



and I cannot accept either the minor or major limits of time arrived 

 at in this way. Perhaps a few more lines are necessary to further 

 amplify my reasons. 



The 19 rivers contain the following compounds, among others, in 

 tons per cubic mile of water : calcium and magnesium carbonates, 

 439,580 ; sodium sulphate, 31,805 ; sodium nitrate, 26,800 ; and 

 common salt, 16,657. One may take the following views of these 

 data and of river water generally in so far as they affect the 

 denominator of the fraction : — 



The Nitrate. — The succession of events in the process of nitri- 

 fication is well known to chemists from the genesis of ammonia 

 and carbonic acid to the final production of ammonium nitrate. 

 The theory is further held that when the ammonium nitrate is 

 changed to sodium nitrate it is by interaction with sodium chloride, 

 and that the latter is of marine origin. This last idea is strongly 

 supported by the composition of the caliche of the South American 

 nitrate industry. The inference is plainly that the sodium in 

 sodium nitrate is cyclic, and no more available in this calculation 

 of the age of the Earth than Triassic salt. Professor Joly makes no 

 allowance for it, nor indeed any mention of it. 



The Common Salt. — I will not reiterate my arguments concerning 

 the part of this compound which is cyclic of short period, as 

 I have sufficiently indicated their nature in my last article. But 

 under this heading the calcium and magnesium carbonates certainly 

 demand attention. These carbonates carry with them on the 

 average probably not less than -01 per cent, of combined chlorine 

 (p. 447), which, as anyone who knows anything of analysis will 



