Many times they passed by the mouths of iguarapes, or little affluents, with black waters.
The coloration of these waters is a very curious phenomenon.

It is peculiar to a certain number of these tributaries of the Amazon, which differ greatly in importance.
Manoel remarked how thick the cloudiness was, for it could be clearly seen on the surface of the whitish waters of the river.
"They have tried to explain this coloring in many ways," said he, "but I do not think the most learned have yet arrived at a satisfactory explanation." "The waters are really black with a magnificent reflection of gold," replied Minha, showing a light, reddish-brown cloth, which was floating level with the jangada.
"Yes," said Manoel, "and Humboldt has already observed the curious reflection that you have; but on looking at it attentively you will see that it is rather the color of sepia which pervades the whole." "Good!" exclaimed Benito.

"Another phenomenon on which the _savants_ are not agreed." "Perhaps," said Fragoso, "they might ask the opinions of the caymans, dolphins, and manatees, for they certainly prefer the black waters to the others to enjoy themselves in." "They are particularly attractive to those animals," replied Manoel, "but why it is rather embarrassing to say.

For instance, is the coloration due to the hydrocarbons which the waters hold in solution, or is it because they flow through districts of peat, coal, and anthracite; or should we not rather attribute it to the enormous quantity of minute plants which they bear along?
There is nothing certain in the matter.
Under any circumstances, they are excellent to drink, of a freshness quite enviable for the climate, and without after-taste, and perfectly harmless.

Take a little of the water, Minha, and drink it; you will find it all right." The water is in truth limpid and fresh, and would advantageously replace many of the table-waters used in Europe.