SALTNESS OF THE SEA. 13 
appearance of a sort of mucous sac of about an inch long, which, 
thrown upon the deck of a ship, emits a light like a rod of iron 
heated to a white heat. Sir John Herschel noted on the surface of 
calm water a very curious form of phosphorescence; it was a polygon 
of rectilinear shape, covering many square feet of surface, and it 
illuminated the whole region for some moments with a vivid light, 
which traversed it with great rapidity. 
The phosphorescence of the sea may also result from another cause. 
When animal matter is decomposed it becomes phosphorescent. The 
bodies of certain fishes, when they become a prey to putrefaction, 
emit an intense light, MM, Becquerel and Breschet have noted 
fine phosphorescent effects from this cause in the waters of the Brenta 
at Venice. Animal matter in a state of decomposition, proceeding 
from dead fish which floats on the surface of ponds, is capable of 
producing large patches of oleaginous matter, which, piled upon the 
water, communicates, to a considerable extent, especially when the 
water is agitated, a phosphorescent appearance. 
Whatever may be the case elsewhere, there are local causes which 
affect the colour of the waters in certain rivers, and even originate 
their names. The Guainia, which with the Casiquaire forms the Rio 
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. A whitish 
colour is characteristic of the Rio Bianco, or White River, and of 
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 River and the Blue River in 
China are: distinguished by the characteristic tint of their waters. 
The Arkansas, the Red River, 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 saé/, of a peculiar flavour, 
slightly acrid and bitter, and a little nauseous. It has an odour 
peculiarly its own, and is slightly viscous. In short, it includes a 
great number of mineral salts, which give it a very disagreeable taste, 
and render it unfit for domestic use. It contains, among the soluble 
substances which exist on the globe, principally chloride of sodium, 
and sulphates of magnesia, of potassium, and of lime. 
