portion of barytic water is dispersed through the rain water, and brought into contact with the carbonic acid, but it involves a great portion of air in its substance, which improves both the taste and the utility of the fluid. _Snow water_, as we have already stated, is destitute of air and other gaseous matters found in rain. According to Liebig, it contains ammonia. It has long been a popular, but erroneous opinion, that it was injurious to health, and had a tendency to produce bronchocele. But this malady occurs at Sumatra, where ice and snow are never seen; while, on the contrary, the disease is quite unknown in Chili and Thibet, although the rivers of these countries are chiefly supplied by the melting of the snow, with which the mountains are covered. Ice is said not to quench thirst, but on the contrary to augment it, and that the natives of the Arctic regions prefer enduring the utmost extremity of this feeling, rather than attempt to remove it by eating of snow,[8] (_Captain Ross_.) 2. SPRING WATER. Rain water, when it falls on high grounds, enters the soil and filtrates through it, until it is stopped by some natural obstacle, when it pushes upwards, and welling out upon the surface, forms springs; the water is therefore merely a modification of rain water. During its passage, however, it almost always takes up some soluble matters, which of course vary according to the nature of the soil. It is purest when it passes through sand or gravel; in a limestone region, it always contains more or less of the sulphate and carbonate of lime, and it generally contains a trace of common salt, and the usual proportions of air and carbonic acid gas. The presence of these is detected by subacetate of lead, which displays the smallest portion of carbonic acid or a carbonate, and nitrate of silver, which detects the muriates by the formation of muriate of silver. Water from melted _ice_ is perfectly wholesome, and is drunk during the summer season, wherever the climate will admit of its being collected and preserved at a moderate expense. In this form, it is a luxury--almost a _necessary_--in the middle states of this country more particularly, “where,” Dr. Dunglison remarks, “there is not a tavern on the road, on the eastern side of the Blue Ridge, that does not furnish ice to the traveller in any abundance.” When sea-water freezes, the ice does not contain the salts. Consequently, when melted, it affords fresh water, and according to the voyagers in high northern and southern latitudes, the water has been found sweet, soft, and wholesome.