254 THE POPULAR SCIENCE MONTHLY. 



masses of saturated ochre-colored water into the sea, and there 

 was a sharp boundary of waves between the clay-yellow tongue 

 which continually licked itself farther into the sea, and the deep- 

 blue salt water. After a few hours the yellow tongue became 

 bordered with a widening green band, so brightly, so poisonously 

 green, that I was induced to apply my whole stock of green (vert 

 Paul Veronese) to the completion of a study on which I tried to 

 fix the phenomenon as truly as possible. Under the blowing of 

 the west wind the tongue stretched itself out farther, to the rocky 

 shore behind the harbor of Nice, around toward the bay of Villa- 

 f ranca ; and when I visited the latter place the next day the water 

 appeared, not steel-blue as usual, but green, fully green ; and the 

 fishermen of the zoological station there complained that no 

 marine animals could be found swimming around, because they 

 had fled from the green water. The blue color returned after a 

 few days. The green was produced by the finer yellow floating 

 matter ; the coarser particles had already sunk. 



The finer matter keeps afloat for a very long time. G. Bischof 

 put some of the flood waters of the Rhine in large casks, and de- 

 posited these in the cellar of the chemical laboratory at Bonn. 

 The finer particles had not yet entirely settled, and the water had 

 not become clear, after several months of absolute stillness. It is 

 plain that in a lake, in which the continual inflow and outflow 

 keep up a constant current, though it be slight and unremarked 

 by ordinary observers, fishermen and rowers, these fine floating 

 particles will never come to rest, and that, since they have a 

 yellow color, this will appear more intense in the deeper parts, 

 because a larger number of yellow particles are floating in the 

 thicker layers of water there. But, farther away, the shades 

 which the floating matters of single brooks and rivers exhibit 

 vary endlessly between gray, yellow, and reddish, and there re- 

 sult the most diversified and delicately shaded mixed colors, with 

 constant variations according to the quantity of floating matter 

 that is carried into the water-basin. Also in the sea, which is 

 never quiet, the fine floating matter keeps afloat for a long time, 

 and is distributed over immensely large surfaces. 



Organic matters, plants and animals, have effects similar to 

 those of mineral substances. The shores are covered with numer- 

 ous plants; they grow on the lakes in all stages of green and 

 brown (many microscopic plants, which cover the rocks as with a 

 slime, are yellow or brown) ; green plants grow on the sea-shores 

 to a depth of thirty metres, yellow and red sea-weeds to a still 

 greater depth, forming semblances of woods and meadows, and 

 mingling their colors with those of the water. Even in north- 

 ern seas there are numerous stationary animals, sponges, solens, 

 mussels, masses of which develop a definite color ; while visitors 



