Slime[1] is one great impurity of water: still, however, if a river of this description is full of eels, it is generally looked upon as a proof[2] of the salubrity of its water; just as it is regarded as a sign of its freshness when long worms[3] breed in the water of a spring. But it is bitter water, more particu- larly, that is held in disesteem, as also the water which swells the stomach the moment it is drunk, a property which belongs to the water at Trœzen. As to the nitrous[4] and salso-acid[5] waters which are found in the deserts, persons travelling across towards the Red Sea render them potable in a couple of hours by the addition of polenta, which they use also as food. Those springs are more particularly condemned which secrete mud,[6] or which give a bad complexion to persons who drink thereof. It is a good plan, too, to observe if water leaves stains upon copper vessels; if leguminous vegetables boil with difficulty in it; if, when gently decanted, it leaves an earthy deposit; or if, when boiled, it covers the vessel with a thick crust.[7]

It is a fault also in water[8] but to have any flavour[9] not only to have a bad smell,[10] at all, even though it be a flavour pleasant and agreeable in itself, or closely approaching, as we often find the case, the taste of milk. Water, to be truly wholesome, ought to resemble air[11] as much as possible. There is only one[12] spring of water in the whole universe, it is said, that has an agreeable smell, that of Chabura, namely, in Mesopotamia: the people give a fabulous reason for it, and say that it is because Juno[13] bathed there. Speaking in general terms, water, to be wholesome, should have neither taste nor smell.