ON AY.V 



AND ITS roMI'<TNI). 



45 



cliicf 



chemical transformations. Further, the quantity and nature of 

 salts differ in different waters. 3 Everybody knows that there 



anhydride 

 of 10 vols. 

 still in abc 

 dominates 

 which .sin 

 succeeded, 

 anhydride, 

 Deville. CO 

 litre. Fir 



M'oeeeding in all likelihood from the soil and not from the atmosphere), and 

 if oxygen. If the total amount of gases be less, the constituent gases are 



h 



>ut the same proportion; in many ca>es, however, carbonic anhydride pre- 

 The water of many deep and rapid rivers contain?-, less carbonic anhydride, 

 \s their rapid formation from atmospheric water and that they have not 

 during a long and slow course, in absorbing a greater quantity of carbonic 

 Thus, for instance, the water of the Khine, near Strasburg, according to 

 itains M c.c. of carbonic anhydride, 16 c.c. of nitrogen, and 7 c.c. of oxygen per 

 n the researches of Prof. M. R. Kapoustin and his pupils, it appears that in 

 determining the quality of a water for drinking purposes, it is most important to investi- 

 gate the composition of the dissolved gases. 



3 Sprinij water is formed from rain water percolating through the soil. Naturally a 

 part of the rain water is evaporated straightway from the surface of the earth and from 

 the vegetation on it. It has been shown that out of 100 parts of water falling 011 the 

 earth only 36 parts flow to the ocean ; the remaining 64 are evaporated, or percolate 

 far underground. The collection of water by means of ponds, common wells, or artesian 

 wells is dependent on the presence of subterranean water. After flowing underground 

 along some impervious strata, water comes out at the surface in many places as springs, 

 whose temperature is determined by the depth from which the water has flowed. 

 Springs penetrating to a great depth may become considerably heated, and this is why 

 hot mineral springs, with a temperature of up to 30 and higher, are often met with. For 

 instance, there is one Caucasian spring whose temperature is 90. Most likely in this 

 Ban the water is heated owing to its penetrating near a rock formation which is heated 

 by volcanic action. The composition of spring water is most varied. When a spring 

 water contains substances which endow it with a peculiar taste, and especially if these 

 substances are such as are only found in minute quantities or not at all in river and 

 other flowing waters, then the spring water is termed a mineral water. Many such 

 waters are employed for medicinal purposes. Mineral waters are classed according to 

 their composition into (a) saline waters, which often contain a large amount of common 

 salt; (b) alkaline waters, which contain sodium carbonate; (c) bitter waters, which 

 contain magnesia ; (d) chalybeate waters, which hold iron carbonate in solution ; (e} 

 aerated waters, which are rich in carbonic anhydride ; ( f ) sulphuretted waters, which 

 contain hydrogen sulphide. Sulphuretted waters may be recognised by their smell of 

 rotten eggs, and by their giving a black precipitate with lead salts, and also by their tar- 

 nishing silver objects. Aerated waters, which contain an excess of carbonic anhydride, 

 effervesce in the air, have a sharp taste, and redden litmus paper. Saline waters leave a 

 large residue of soluble solid matter on evaporation, and have a salt taste. Chalybeate 



