Substantially the same result, with variations due to local causes, as exemplified in the varying composition of river and drain waters, is obtained when we consider the saline ingredients of lakes having no outlet, and in which therefore, the leachings of the tributary land area have accumulated for ages. The Great Salt Lake of Utah, the landlocked lakes of the Nevada basin, of California, Oregon, and of the deserts of Asia, Africa, and Australia, all tell the same tale, which may be summarized in the statement that the chlorids of sodium and magnesium, and the sulfates of sodium, magnesium and calcium constitute the bulk of the leachings of the land; while of other substances potassium alone is present in relatively considerable amount. While the above analysis shows the ingredients of sea-water so far as they can at present be directly determined by chemical analysis, yet the presence of many others is demonstrable, directly or indirectly, from various sources. One is, the mother-waters from the making of sea-salt, in which such substances accumulate so as to become ascertainable by chemical means, and even become industrially available in the cases of potash and bromin. Another is the ash of seaweeds, which is indisputably derived from the sea-water, and contains, among other substances not directly demonstrable in the original water, notable quantities of iodin (of which this ash is a commercial source), iron, manganese, and phosphoric acid. Again, the copper sheathing of vessels, as it is gradually corroded, becomes more or less rich in silver, manifestly thrown down from the sea-water, and the silver so obtained is associated with minute amounts of gold. Copper, lithium, and fluorin likewise have been found in sea water; and it is probable that close search would detect very many of the other chemical elements as ordinary ingredients in minute amounts. This is what must be expected from the fact that few mineral substances known to us are entirely insoluble in pure water, and still fewer in water charged with carbonic acid. The latter is always present in sea-water and holds the lime carbonate in solution; on evaporation or boiling, this substance is the first to be precipitated; and thin sheets of limestone from this source are commonly found at the base of rock-salt beds, which, themselves, are evidently the result of the evaporation of segregated bodies of sea-water in past geological ages.