SALTNESS OF THE SEA. 15 



affect the colour of the waters in certain rivers, and even originate 

 their names. The Guamia, which with the Casiquaire forms the Eio 

 Negro, is of a deep brown, which scarcely interferes with the limpidity 

 of its waters. The waters of the Orinoco and the Casiquaire have 

 also a brownish colour. The Ganges is of a muddy brown, while the 

 Djumna, which it receives, is green or blue. The whitish colour 

 belongs to the Kio Bianco, or White Kiver, and to many other rivers. 

 The Ohio in America, the Torgedale, the Goetha, the Traun at Ischl, 

 and most of the Norwegian rivers, are of a delicate limpid green. The 

 Yellow Kiver and the Blue Kiver in China are distinguished by the 

 characteristic tint of their waters. The Arkansas, the Ked Kiver, and 

 the Lobregat in Catalonia, are* remarkable for their red colour, which, 

 like the Dart and other English rivers, they owe to the earth over 

 which they flow, or which their waters hold in suspension. 



The water of the sea is essentially salt, of a peculiar flavour, slightly 

 acrid and bitter, and a little nauseous. It has an odour perfectly sui 

 generis, and is slightly viscous. In short, it includes a great number 

 of mineral salts and some other compounds, which give it a very dis- 

 agreeable taste, and render it unfit for domestic use. It contains 

 nearly all the soluble substances which exist on the globe, but 

 principally chloride of sodium, or marine salt, and sulphate of magnesia, 

 of potassium, and of lime. 



Pure water is produced by a combination of one volume of oxygen 

 and of two volumes of hydrogen, or in weight, 100 oxygen and 12'50 

 hydrogen. Sea water is composed of the same ; but we find there, 

 besides, other elements, the presence of which chemistry reveals to us. 

 In 1000 grains of sea water the following ingredients are found: 



Water 962'0 



Chloride of sodium 27*1 



Chloride of magnesium 5'4: 



Chloride of potassium 0*4 



Bromide of magnesia O'l 



Sulphate of magnesia 1*2 



Sulphate of lime 0'8 



Carbonate of lime O'l 



Leaving a residuum of .... 2-9 



1000 



consisting of sulphuretted hydrogen, hydrochlorate of ammonia, iodine 



