SALINE CONTENTS OF SEA-WATER. 409 



highly charged with saline matter than the 

 waters of the ocean outside the Straits ; an 

 effect which appears to be due to the immense 

 evaporation taking place from its surface, which 

 carries off an enormous volume of water in the 

 form of vapour, to supply the place of which a 

 strong current sets in from the main ocean, 

 through the Straits of Gibraltar. In other in- 

 land seas, on the contrary, the amount of saline 

 matter is diminished; and this is the general 

 rule. The explanation of this appears to be, 

 that such seas generally receive a very large 

 addition of fresh-water from the coast around 

 them, and from one or more great rivers which 

 may flow into them. The Baltic Sea is thus 

 remarkably contrasted with the Mediterranean; 

 for while the latter has a high density, pro- 

 bably about 1029 or 1030 pure water being 

 1000 the waters of the former have a density 

 very little higher than 1015. Near the mouths 

 of great rivers, as is naturally to be expected, 

 the quantity of the saline contents of sea-water 

 is much lessened; the fact being, that the 

 waters of the ocean are in reality diluted by 

 the intermixture of a large body of fresh- 

 water. It is said that the diluting influence of 

 the great American river, Amazon, is distinctly 

 perceptible for a distance of upwards of 300 

 miles from its mouth. 



Professor Forchhammer has made some highly 



