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reached the surface, although it rose to within a few feet of it. This fact was afterwards accounted for by the discovery that the sheet of water which supplied this boring, being the same that feeds the fountains of St. Ouen and Saint Denis, crops out on the banks of the river Seine, between Chaillot and Saint Cloud. From this sheet, that which supplies the wells at Tours and Elbœuf is separated by the entire chalk formation. M. Champoiseau communicated to the Academy of Sciences, in 1840, the result of experiments he had made at Tours, to ascertain if any connexion existed between his Artesian Well and the neighbouring rivers. These experiments were conducted during the months of March, April and May, while the waters of the rivers were fluctuating, but no corresponding change was found in the well-waters which did not show any variation either in their quantity or clearness. The temperature of the water of Grenelle was found to be 810-7 Fah., and its quality far more pure than that of the Seine, or of Arcueil. From an analysis by M. Pelouze, it appears that 100 cubic inches of the Grenelle water gave only 3.5 grains of extraneous matter, whilst a similar quantity of water, from Arcueil or the Seine, yielded 4.3 grains mechanically suspended, and 116 grains of chemical impurities.

28. Borings similar to those for Artesian Wells have been executed for the purpose of getting rid of superfluous water and liquid matters. An embankment near Val de Fleury, for the left bank Versailles Railway, was drained in this manner by means of absorbing wells. A stratum of clay and sand soaked with the rains of the previous year forced the bank from its position, and destroyed the works. Borings were made, the first of which reached 20 yards in depth, where it arrived at the upper part of the chalk, full of fissures, and which

speedily absorbed the water. The subsequent borings were carried to 35 and 40 yards, in order to reach the chalky fissures which communicate with the Seine, and feed the neighbouring wells. Absorbing wells have also been used in France to dispose of the refuse of the laystalls. M. Mulot, who superintended the Grenelle Artesian Well, executed a boring for this purpose at Baudy. Through a perforation 244 feet in depth, two absorbing strata were obtained, one at a depth from 133 to 155 feet in chalk mixed with silex, and the other from 210 to 244 feet, in argillaceous sand, and green and gray sands containing lignites and pulverized shells. By the first, 70, and the latter, 140 cubic yards of refuse liquid were absorbed.

29. On the peculiar qualities of water depends its fitness for agricultural, manufacturing, and domestic purposes. Chemical researches have put us in possession of much valuable knowledge upon this subject, which it behoves the land-worker and the engineer equally to avail themselves of. Pure water, as proved by the early experiments of Priestley and Cavendish, about the year 1780, consists of the two gases, oxygen and hydrogen, in the proportion of 85 parts, by weight, of oxygen, to 15 of hydrogen. This pure liquid can be obtained only by distilling water as it is found in the several states of rain-water, river-water, sea-water, and spring-water. The water obtained from each of these sources contains foreign matters of some kind, the nature and effects of which, as ingredients in the water we have to employ, are well deserving our best attention.

30. Liebig has proved, by experiments made in the laboratory at Giessen, that rain-water contains ammonia. All the rain-water used for these experiments was collected at a distance of 600 paces (south-west) from the town, and while the wind was blowing towards it.

Several hundred pounds of the water were distilled in a copper still, and, upon evaporating some of it with muriatic acid, an evident crystallization of sal-ammoniac was observed. The same eminent chemist has fully satisfied himself of the presence of ammonia in snowwater. By evaporating the snow with muriatic acid, crystals of sal-ammoniac were obtained; and from these crystals the ammonia was liberated by adding hydrate of lime. In these experiments Liebig observed that the inferior strata of snow always contained a larger proportion of ammonia than that lying upon the surface. The origin of this ingredient and its utility in the vegetable economy are details of a most interesting study, but we cannot afford space to pursue the inquiry.

31. Sea-water contains, besides carbonic acid, ammonia, &c., the following salts :-according to Marcet,

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making a total of 39.204 parts of salts in 1000 parts of sea-water. An analysis of the water of the North Sea, made by Clemm, differs slightly from this. Clemm's is as follows:

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showing a total of 31.83 parts of salts in 1000 parts of sea-water. These salts are, by the constant evaporation from the surface of the sea, floated over the earth and carried down by the rain, thus replenishing vegetation with the salts essential to its growth and existence.

32. The waters obtained from rivers, springs, and wells, are all impregnated in a greater or less degree with foreign substances, and also hold others in a state of mechanical suspension. These impurities are of four kinds, viz.:

1st. The Mechanical.

2nd. The Animal.

3rd. The Vegetable.

4th. The Mineral or Saline.

Although the purification of water from these matters may belong peculiarly to our Second Division, it will be well to consider it under the first, in order to establish correct notions of the qualities of water, whether applied to agricultural, manufacturing, or domestic uses. The process of filtration separates only the first of these. The saline matter contained in water may be distinguished as neutral and alkaline. The neutral salts are gypsum, common salt, &c. The alkaline portion consists of earthy bicarbonates, such as those of lime and magnesia, and alkaline bicarbonates, such as those of potash and soda. The principal cause of that quality of water, termed "hardness," arises from the presence of the earthy salts mentioned, and sometimes iron-salts; and the same property is evinced if the water contain an excess of carbonic acid. Exposure to the air will diminish the hardness of water, as far as that quality is occasioned by the excess of carbonic acid; and it will have a similar effect, but in a much diminished degree,

upon waters which owe their hardness to the presence of the earthy bicarbonates.

33. The economical results dependent upon the qualities of the water supplied to towns are of extreme importance, and therefore deserve attention. Thus, the bicarbonates of lime, &c., affect, to a great degree, the value of water in its application to many manufacturing purposes, and to the production of steam and the heating of pipes for artificial warming. The incrustation of boilers is a well-known theme of consideration in the economy of steam power, and, moreover, frequently becomes operative as the ultimate cause of accidents, in the case of explosions. In its domestic applications, the properties of water are equally important. The quality of hardness occasions a necessity for a great additional consumption of soap in all the processes of washing and cleansing. And this resistance to the cleansing action becomes, as is universally known, the cause of increased mechanical effort on the part of the operator, and a corresponding increase of wear and injury to the clothes acted upon. Dr. T. Clark, who has given much attention to this subject, and is the patentee of a process for testing the hardness of water, conceives that a very considerable expenditure arises from these causes in a large town supplied with hard

water.

34. For the purpose of comparison, Dr. Clark adopts the effect of the presence of one grain of chalk in one gallon of water as a standard, or one degree of hardness; and he gives the results of some of his analyses as follows:-The hardness of the waters supplied through pipes in London varies from 11° to 16o, or equal to the effect of 11 to 16 grains of chalk per gallon. The pipe-water of Manchester has 12° of hardness. The

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