1902-3.] The Pal^ochemistry of the Ocean. 537 



estimated to be in the annual river discharge of the globe. Joly took 

 for these the results of Murray,* who, basing his calculations on the 

 discharge of nineteen of the principal rivers of the world, estimated the 

 total amount of the sodium and other salts annually put into the sea by 

 river water, Joly finds from Murray's tables that the sodium annually 

 discharged is 157,270,000 tons, and the quantity in the sea is 14,151,- 

 000,000,000,000 tons. Dividing the latter by the former he gets as 

 quotient, approximately, 90,000,000, which, expressed as years, would 

 be the age of the earth, or, rather, the period of time which has elapsed 

 since the first condensation of water vapour took place on the globe. 

 Joly admits that the ocean at first contained a considerable quantity of 

 sodium as sodium chloride, and this he puts at about 14 per cent, of the 

 present amount in the sea. This would make the amount discharged 

 into the sea by river water less than that stated above, but, on the other 

 hand, the volume of the ocean may, as a result of more recent estima- 

 tions, be given a higher value, and in consequence the mass of sodium in 

 it would be 15,627,000,000,000,000 tons. Further, of the sodium 

 annually put into the ocean, Joly allows as much as 10 per cent, for that 

 which is taken from the ocean by the rain and returned again in river 

 water, and this estimate would make the amount of river sodium, which 

 is annually leached out of the rocks and strata, as 97,800,000 tons. 

 With these values Joly finds that the corrected figures for the age of 

 the earth is 89,300,000 years. 



In support of his contention Joly shows that as compared with the 

 igneous rocks there is in the sedimentary rocks, which are derived from 

 them, a deficiency of sodium, and that the sodium now in the sea would 

 approximately account for the difference. The bearing of this fact is 

 that all the sodium now in the ocean was derived from the original 

 rock crust by processes which to-day are in operation in decomposing 

 rock material and removing the sodium therefrom. In other words, the 

 discharge of sodium into the sea has been in the past a uniform one, or 

 at least subject to no great variations that would constitute a factor 

 against determining the age of the earth by this method. 



This estimate has been ably criticized by the eminent geologist, 

 the Rev. Osmond Fisher,-|- who points out that the sodium which is 

 derived from the decomposition of crystalline or igneous rocks is in the 

 form of carbonate rather than chloride ; and he asks whether it is not 

 possible that the chloride of river water is derived, not from crystalline, 



* On the Total Annual Rainfall on the Land of the Globe, and the Relation of Rainfall to the Annual 

 Discharge of Rivers. The Scottish Geogr. Mag-., Vol. 3, 1887, p. 65. 

 t Geol. Mag-., New Ser., Vol. 7, p. 124, 1900. 



