THE SALTS OF THE SEA WHENCE DERIVED AND HOW THEIR UNIFORM PROPORTION IS MAINTAINED Generally speaking, the waters of the ocean may be said to be universally uniform as regards the proportions of saline matters held in solution, and we have no proof that this remarkable and universal uniformity of composition has ever undergone any alteration. On the contrary, we have reason to believe that the waters of the ocean, even in the earliest geological ages, were as salt as they are now, for the fossil fauna of the earth comprises numerous species that could not have existed in fresh water, or indeed in any water perceptibly different in composition to that of the present sea-water. Bearing in mind the striking fact that the degree of saltness is pretty nearly the same throughout the whole extent of the ocean, and that the proportions of ingredients most probably has never changed, we naturally desire some solution to the queries—(1) Whence did the waters of the ocean originally derive their salts I and supposing their origin to be satisfac torily accounted for, (2) How can we explain the remarkable uniformity in the composition of sea-water throughout the whole extent of the ocean 4 and further, (3) What are the results of the saltness of the ocean.
In the first place, whence did the waters of the ocean originally derive their salts? This problem is from its very nature incapable of other than an indirect solution and demon stration. Several theories, all more or less plausible, have been advanced with the object of satisfactorily accounting for the presence of salts in the waters of the sea. The generally received opinion is that they were originally derived from the "washings of the rains and the rivers." The condensed moisture in the air falls on the land in the shape of rain and avow, moistening all the exposed surfaces, and dissolving every substance which it can hold in solution, and percolating through the softer, and passing over the harder surface strata, gradually collecting and forming small streams, a number of which uniting their waters form a river, which finally discharges the collected waters of its basin, laden with the "spoils of the land," into the sea. Of the many substances dissolved from the time it reached the ground as rain, to its final reception in one mighty flood by the sea, the more readily dissolved substances will, of course, be carried down in greater quantities than the others. And we find that nearly all the saline matters found in the waters of the ocean are always present in the so-called fresh water of all rivers, though, of course, in a scarcely appreciable quantity. But though comparatively small in any given portion of even the larger rivers, yet the total quantity of saline substances carried into the ocean by all the rivers of the globe must be enormous ; and in this way alone, supposing the ocean to have been fresh in former periods, its present saltness may be easily accounted for—the salts gradually accumulating and being evenly dif fused through the mass of the ocean by the constant circulation of its waters.
It may be objected to this theory that the waters of the ocean must in course of time get perceptibly salter, fot not a particle of the saline substances brought down by rivers is ever removed by evaporation. Fresh water alone being capable of conversion into water, the salts are left behind, and must therefore accumulate. But repeated geological researches show most conclusively that there has been no such change as this would necessarily involve, and that, as regards its component parts, the ocean must long since have arrived at a state of equilibrium ; the continual supplies of saline matters being equalized, or nearly so, by the incessant de mands of the myriad forms of marine organisms with which the ocean teems ; any amount still in excess being most probably chemically involved in the formation of new strata at the bottom of the sea, Maury, the great phy sical geographer of the sea, while admitting the fact that " rains and rivers do dissolve salts of various kinds from the rocks and soil, and empty them into the sea," still dissents from the theory that the sea originally derived its salts in this manner. He contends that "if the sea derived its salts
originally from the rivers, the geological records of the past would show that river beds were scored out of the crust of our planet before the sea had deposited any of its fossil shells and infusorial remains upon it" He states further, that if this be true, there must have been a time when there either was no sea, or that it was fresh, and consequently without "shells or animals of the silicious or calcareous kinds." But both Palaeontological records and the Mosaic account of the Creation prove the contrary ; and, on the double evidence of geology and inspiration, he believes that the " fossil shell and the remains of marine organisms inform us, that when the foundations of our mountains were laid with granite, and im mediately succeeding that remote period when the primary formations were completed, the sea was, as it is now, salt." The objection that may be made as to the absolute quantity of solid matters in solution in the waters of the sea is not so relevant, and may be met with the plea that although the amount of saline matters annually consigned to the sea by the rivers of the globe may be comparatively insignificant, yet, as we cannot tell how many ages have elapsed since the process began, the amount carried down altogether would suffice to account for the present saltness. Even if we con sider the total quantity—taking the proportion of salts to be 3.5 per cent —estimated to be sufficient to cover an area of 7,000,000 square miles to a depth of one mile, as rather over than under the actual quantity, still it may be probable that, in the course of time, the rivers, which furrow almost every part of the surface of the land, aided by the movements of the sea itself (more especially the incessant action of its waves on thousands of miles of coast, perpetually disin tegriting the exposed strata along the shore-line), may have gradually accumulated the amount of saline ingredients we now find dissolved throughout the mass of the ocean.
Another theory, evidently an outgrowth of the preced ing one, supposes that the waters of the ocean were originally fresh, but acquired their present saltness by dissolving the saline materials in the exposed strata of its basin—the uni formity of proportion being simply the result of the admixture and mingling of its waters.
But the most probable solution of this problem is, that the waters of the ocean " have always been salt, ever since they were condensed out of the original atmosphere of gas and vapour, and carried down the saline vapours which were no doubt at first diffused abundantly through that atmosphere."' This theory harmonizes with the consistent records of palaeontology, which certainly do not support the idea that the ocean was originally fresh, and consequently devoid of nearly all, if not all, its characteristic organisms. We cannot tell why so many marine organisms have died out ; but if it was because the sea got gradually salter, why did not the coral insect, vihose records probably point to a date anterior to several of them, perish and become extinct likewise I As Maury aptly remarks, the various marine animals which have become extinct, died out because they " ceased to find the climates of the sea, not the proportion of its salts, suited to heir well-being.'