Slime[3017] 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[3018] of the salubrity of its water; just as it is regarded as a sign of its freshness when long worms[3019] breed in the water of a spring. But it is bitter water, more particularly, 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[3020] and salso-acid[3021] 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,[3022] 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.[3023]
It is a fault also in water,[3024] not only to have a bad smell,[3025] but to have any flavour[3026] 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[3027] as much as possible. There is only one[3028] 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[3029] bathed there. Speaking in general terms, water, to be wholesome, should have neither taste nor smell.
CHAP. 23.—THE MODES OF TESTING WATER.
Some persons judge of the wholesomeness of water through the agency of a balance:[3030] their pains, however, are expended to little purpose, it being but very rarely that one water is lighter than another. There is, however, a more certain mode of ascertaining the difference in quality, that water being the better of the two which becomes hot and cold with the greatest rapidity: in addition to which, not to keep poising a balance,[3031] after water has been drawn up in vessels, if it is good, it should gradually become warmer, they say, when placed upon the ground. Which water, then, of the several kinds will be most likely to be good and wholesome? Well-water, no doubt if we are to judge from the general use made of it in cities: but only in the case of wells in which it is kept in continual agitation by repeated drawing, and is refined by the earth acting as a filter. These conditions are sufficient to ensure salubrity in water: in regard to coolness, the well must be in a shaded spot, and the water kept exposed to the air. There is, however one thing above all to be observed, a point, too, of considerable importance with reference to the continuance of the flow—the spring must issue from the bed of the well, and not from the sides. To make water cold to the touch may be effected artificially even, either by forcing it to rise aloft or by making it fall from a height, and so come in collision with the air, and become incorporated[3032] therewith: for in swimming,[3033] we find, when we hold our breath, the water is felt to be all the colder.
It was the Emperor Nero’s invention[3034] to boil water, and then enclose it in glass vessels and cool it in snow; a method which ensures all the enjoyment of a cold beverage, without any of the inconveniences resulting from the use of snow. Indeed, it is generally admitted that all water is more[3035] wholesome when it has been boiled; as also, that water when it has once been heated, will become more intensely[3036] cold than before—a most ingenious discovery.[3037] The best corrective of unwholesome water is to boil it down to one half. Cold water, taken internally, arrests hæmorrhage. By keeping cold water in his mouth, a person may render himself proof against the intense heat of the bath. Many a person knows by his own every-day experience, that water which is the coldest to drink is not of necessity the coldest to the touch, this delightful property being subject to considerable fluctuations.[3038]
CHAP. 24.—THE MARCIAN WATERS.
The most celebrated water throughout the whole world, and the one to which our city gives the palm for coolness and salubrity, is that of the Marcian[3039] Spring, accorded to Rome among the other bounties of the gods: the name formerly given to the stream was the “Aufeian,” the spring itself being known as “Pitonia.” It rises[3040] at the extremity of the mountains of the Peligni, passes through the territory of the Marsi and through Lake Fucinus, and then, without deviating, makes directly for Rome: shortly after this, it loses itself in certain caverns, and only reappears in the territory of Tibur, from which it is brought to the City by an arched aqueduct nine miles in length. Ancus Marcius, one of the Roman kings, was the first[3041] who thought of introducing this water into the City. At a later period, the works were repaired by Quintus Marcius Rex: and, more recently, in his prætorship, by M. Agrippa.[3042]
CHAP. 25.—THE VIRGIN WATERS.
It was he, too, who brought the Virgin[3043] Waters from the bye-road situate at the eighth milestone from the City, which runs for two miles along the Prænestine Way. Near these waters is the stream of Hercules, which the former shun, to all appearance, and have thence obtained[3044] the name of “Virgin Waters.” On instituting a comparison between the waters of these streams, the difference above-mentioned[3045] may be immediately detected, the Virgin water being as much cooler to the touch, as the Marcian water is in taste. And yet, for this long time past, the pleasure of drinking these waters has been lost to the City, owing to the ambition and avarice of certain persons who have turned[3046] them out of their course for the supply of their country-seats and of various places in the suburbs, to the great detriment of the public health.