Page:Physical Geography of the Sea and its Meteorology.djvu/293

Rh have not made the sea any fuller. All this solid matter has been received into the interstices of sea water without swelling the mass; for chemists tell us that water is not increased in volume by the salt it dissolves. Here we have therefore displayed before us an economy of space calculated to surprise even the learned author himself of the "Plurality of Worlds."

496. The saltness of water retards evaporation.—There has been another question raised which bears upon what has already been said concerning the offices which, in the sublime system of terrestrial arrangements, have been assigned to the salts of the sea. On the 20th of January, 1855, Professor Chapman, of the University College, Toronto, communicated to the Canadian Institute a paper on the "Object of the salt condition of the sea," which, he maintains, is "mainly intended to regulate evaporation." To establish this hypothesis, he shows by a simple but carefully conducted set of experiments that, the Salter the water, the slower the evaporation from it; and that the evaporation which takes place in 24 hours from water about as salt as the average of sea water is 0.54 per cent, less in quantity than from fresh water. "This suggestion and these experiments give additional interest to our investigations into the manifold and marvelloiis offices which, in the economy of our planet, have been assigned by the Creator to the salts of the sea. It is difficult to say what, in the Divine arrangement, was the main object of making the sea salt and not fresh. Whether it was to assist in the regulation of climates, or in the circulation of the ocean, or in re-adapting the earth for new conditions by transferring solid portions of its crust from one part to another, and giving employment to the corallines and insects of the sea in collecting this solid matter into new forms, and presenting it under different climates and conditions, or whether the main object was, as the distinguished professor suggests, to regulate evaporation, it is not necessary now or here to discuss. I think we may regard all the objects of the salts of the sea as main objects. But we see in the professor's experiments the dawn of more new beauties, and the appearance of other exquisite compensations, which, in studying the 'wonders of the deep,' we have so often paused to contemplate and admire:—As the trade- wind region feeds the air with the vapour of fresh water, the process of evaporation from the sea is checked, for the water-which remains, being salter, parts with its vapour less readily; and thus, by the salts of the sea, floods may be prevented. But