420 
ACKROYD : OX THE CIRCULATION OF SALT. 
The Age of the Earth. 
From the ground of solid fact we come to an atmosphere of 
speculation in returning to a final consideration of the validity, or 
otherwise, of the method of finding the Earth's age, since seas were 
formed, by the expression : 
Sodium in the seas 
= Age of the Earth. 
Sodium annually added by the rivers 
My view of the matter is directed by one striking fact, which is 
that all the sodium in the sea exists, to all intents and purposes, in 
the 39,782 billions of tons of common salt which has been calculated 
to be there in solution. Now if there has been uniformity from the 
first, or " constancy in the nature and rate of solvent actions going 
on over the land surfaces" (Joly, Trans. Roy. Soc. Dublin, Ser. 11. , 
Vol. VII., page 24), it necessarily follows that all this sodium chloride 
in the ocean has gone there as such, or, at any rate, that all the sodium 
going there has finally taken the form of chloride. It is on such 
considerations that my criticisms of this method have, from the first, 
been based, and, to be strictly consistent, if the numerator consists 
of common salt only, then the denominator ought to be made up of 
the same material. Let us critically examine, however, this de- 
nominator, and we shall really find that much, if not all, of it consists 
of cyclic sodium as I have already attempted to prove by other con- 
siderations. The sodium in it comprises 10,303 tons as sulphate, 
7,252 tons as nitrate, and 6,549 tons as chloride. Of this last not 
less than 43 per cent, has come in the prodigious quantity of calcium 
and magnesium carbonates, and is represented in analyses of these 
bodies as 0-01 per cent, of chlorine. Then an unknown proportion 
of " fossil sea-salt from other sources " is included in this chloride, 
as shown by the researches of Sterry Hunt, Osmond Fisher,* and 
A. R. Hunt.t Probably all the rest is cyclic sea-salt. As regards 
the nitrate, it is not improbable again that all of it owes its origin to 
cyclic sea- salt. The chemical argument on this point is interesting, 
and may be thus given : — In the first stage of nitrification we have 
*Oeol. Mag., March, 1900, pp. 120 and 180. 
fOeol. Mag., March, 1901, pp. 1-8. 
