I902-3-] The Pal^ochemistry of the Ocean. 545 



after a long period of time become appreciable in the ocean. The 

 carbonic acid in the rain water must have acted, as it does now, on the 

 silicates of sodium, potassium and calcium in the rocks and produced 

 free silica and carbonates of these elements, these latter going into 

 solution and thus reaching the ocean, where, acting on the chloride of 

 calcium, carbonate of lime and chloride of sodium and potassium would 

 be formed. The calcium carbonates would be removed by deposition 

 and thus constitute the origin of the limestone beds of the pre-Cambrian " 

 age, but the chlorides remaining in solution, thus contributed to an 

 increase in the amount of sodium and potassium in the sea water.* 



The sulphates in the rock crust disintegrated or affected would also 

 be carried to the sea, but, as these would be small in quantity, they need 

 not be specially considered here. 



Thus the history of the sea must have begun and continued for a 

 period of unknown length. The only change came from the discharge 

 into the sea of the carbonates, the consequent removal of the lime and 

 the slow increase in amount of magnesium, sulphuric acid, and of potas- 

 sium and sodium. The two latter elements were not removed from the 

 sea except through the rainfall. As I shall presently point out, the pot- 

 assium compounds are to-day removed from the ocean apparently as 

 rapidly as they are added by river water, and, in consequence, the 

 amount in sea water now appears to be stationary. In the earliest 

 geological period the conditions which now contribute to this result did 

 not exist, and the ocean retained all the potassium it held or received 

 through river discharge. In all probability the potassium equalled, and 

 even exceeded, the sodium in amount.f When sediments began to form, 

 and, when soils made their appearance, then, and then only began the 

 elimination of the potassium from the ocean. It has been long estab- 

 lished that potassium manifests a marked capacity to unite with silicates 

 of alumina to form firm compounds, and these obtain whenever potassium 

 salts in solution come in contact with argillaceous material, sedimentary 

 or otherwise,:!: while the sodium, magnesium, and calcium are unaffected. 



* Sterry Hunt (Chemical and Geological Essays, Boston, 1875) held the view that the most abundant 

 constituent in primeval sea water was calcium chloride, and that with the gradual addition of sodium carbon- 

 ate calcium was removed as carbonate and sodium chloride consequently took its place. 



t Joly {loc. cit.) assumes that the greater part of the chlorine now in the ocean was originally united with 

 the iron, calcium, magnesium, potassium, and sodium, these elements entering into combination in proportion 

 parallel to the proportions in the rockcrust as determined by F. W. Clarke {loc. cit.) This postulates that 14 

 per cent, of the chlorine now in the ocean was united with sodium, and consequently the ocean origmally 

 contained about one-seventh of the sodium it now holds. As the proportion of sodium to potassium in the 

 rock crust is 100 to 95, on Joly's hypothesis the potassium in the primaeval ocean must have really equalled 

 in amount the sodium therein. Joly, however, is in error in supposing that the chlorides of magnesium and 

 iron could have existed, and he should consequently have made a greater allowance for the amounts of chlorine 

 combined with the sodium, potassium, and calcium. 



) Sterry Hunt (op. cit. p. 95.) 



