644 SALINITY AND SPECIFIC GEAVITY. 



prevailing Btrong acid ; that, lastly, the great stability of its composition 

 depends upon its enormous mass and its constant motion, which occasions 

 that any local variation is evanescent compared to the whole quantity 

 of salt. 



" If we take the mean numbers for the five regions of the Atlantic be- 

 tween the southernmost point of Greenland and that of South America, 

 we find the mean quantity of salt for the whole Atlantic 35*833, while the 

 sea between Africa and the East Indies has only 33-850 ; the sea between 

 the East Indies and the Aleutian Islands, 33-569 ; and the South Sea, 

 between the Aleutian Islands and the Society Islands, 35-219 per 1,000 

 salt. The Atlantic is thus that part of the Ocean which contains the 

 greatest proportion of salt, which result is rather surprising, if we consider 

 the vast quantity of fresh water which the rivers of Africa, America, and 

 Europe pour into it ; of Africa, four-fifths are drained into the Atlantic, 

 either directly or through the Mediterranean ; most probably nine-tenths 

 of America is drained into the Atlantic, since the Cordilleras run close to 

 the western shore of the continent ; and of Europe, also, about nine-tenths 

 of its surface sends its superfluous water to the Atlantic. This greater 

 quantity of fresh water from the land, and the greater quantities of salts 

 in the corresponding sea, seem to contradict each other, but can be ex- 

 plained by a higher temperature, and, as the result of this higher tem- 

 perature, a greater evaporation. 



" Some of the large bays of the Ocean have, in the Tropical or sub- 

 Tropical zones, a greater meaa than the Atlantic. Such are the Mediter- 

 ranean, with 37*936 per 1,000 salt (mean of eleven observations) ; the 

 Caribbean Sea, with 36-104 per 1,000 (one observation) ; the Eed Sea, 

 43-067 per 1,000 (mean of two but little differing observations), which is 

 the greatest salinity of the sea I know of. 



" In approaching the shores, the sea- water becomes less rich in salts, a 

 fact which finds its explanation in the more or less quantity of fresh water 

 which runs into the sea. On such shores, where only small rivers flow out, 

 the effect produced is but very trifling, as, for instance, on the western 

 shores of South America. The effect of large rivers in diluting the sea- 

 water is much greater than is generally supposed ; thus, the effect of the 

 La Plata Eiver, whose mouth lies in about 35° South latitude, was still 

 observable in a sample of sea-water taken in 60° 31' S., at a distance of 

 15° of latitude, or 900 English miles, from the mouth of the river ; at about 

 the same distance, the water of the North Atlantic suffered a considerable 

 depression in salinity, probably owing to the wq,ter of the St. Lawrence. 

 This influence is of a double kind, partly in diluting the sea-water, partly 

 in mixing up with it organic substances that will occasion its decomposition 

 by putrefaction." 



Mr. J. y. Buchanan, from observations made on the cruise of H.M.S. 

 Challenger, shows that in the North Atlantic Ocean, the area of maximum 

 surface Salinity, over 37-2 parts per 1,000, forms an eUipsis stretching 

 W.S.W. from the Canary Islands to lat. 22° N., long. 55° W. ; but 

 Dr. Kriimmel, from his examination of numerous reliable observations,* 



• " Die Verteilung des Salzgehaltes an der Oberfliiche des Nordatlantischen Ozoans," 

 ^ith a Chart, in " Petermann's Mitteilungen," 1890, pages 174 — 176. 



