Turbsdity or a precipitate which follows upon the addition of barite water indicates the presence of carbonic acid; chloride of barium is used in the same way as a test for sulOates; **ate of silver for chlorides; 0=Ute of ammonia for lime salts; sidphide of hydrogen. slightly acid, for salts of antimony, arsenic, bismuth, calcium, copper, gold, lead, mercury. platinum, silver and nisi an alkaline (by ammo ma) solution of sulphide of ammonium, for salts of aluminum, chromium, cobalt. iron, manganese, nickel and zinc. Chloride of gold or mercury and the sulphate of zinc are the for organ—ic matter.
duels of water is a quality that bears Chiefly upon its use for boilers and for laundry purposes. The hardening impurities are pnn °pally the salts of lime and magnesia. Their carbonates produce temporary hardness which may be removed by boiling, when the carbonic acid is dissipated and the insoluble bases are deposited as incrustations on the bottoms of the kettles and boilers. The carbonates are less troublesome to the human constitution than to steam users, but the sulphates, chlorides and nitrates of hose cannot be dissipated by ordinary boiling and are productive of what is known as permanent hardness. Ordinarily pure water can take up only about two grains of carbonate of lime per imperial gallon of 70.000 grains, but when carbonic acid is present, that amount of water will dissolve as much as 20 grains of the carbonate. The degree of hardness is esti mated accordiag to the number of grains of soap the solution is capable of neutralising. Thus, one, two and three degrees of hardness represent the neutralization of 10, 20 and JO grains of soap, respectively. The amount of waste, in the wear of clothes and soap, and the destruction of many valuable food properties by the use of bard water is not fully appreciated by the general public. It is safe to state that the money value of that waste far exceeds the cost that would supply an abundance of water for domestic purposes from a source free from impurities.
Systematic processes for softening water have been employed in the United States, prin cipally in connection with manufacturing plants. The first process was invented by Prof. Thomas Clark. of Aberdeen, Scotland, in 1841, and consists of mixing the water supply with lime water or milk of lime, and allowing it to subside for a period ranging from 12 to 24 hours, when the water is drawn off while the precipitate is left behind. The first softening plant in connection with a municipal water sup ply in America is that connected with the water works of the city of Winnipeg, Monitoba. The source of supply is a number of artesian wells, and the water obtained is very hard. The softening process employed is a modification of that of Clark, and includes a variety of set tling and filtering devices, into which the water is pumped and mixed with the lime solutions and then drawn off and distributed by direct pressure pumping into the mains. Its working provides a water more beneficial to the health, and better for domestic purposes, than that of the Red River, which formed the•original water I the city. (See WATER SOFTEN I NG ) .
'hie boiling is a very cheap and thoroughly effective process of purifying water, and may be used by householders in general, distillation, owing to its expense, may be employed only in special cases, in connection with artificial ice plants, the conversion of salt water into fresh water at sea, and in the various industrial arts.
It will be noted, however, that both boiled and distilled water are unpalatable unless aerated before used for drinking.
Sources of water supply will be found exten sively treated under that title. In a general way, the origin of all sources is the atmosphere. It is a simple matter to trace the course of the water from the clouds in the form of rain to the rivu lets which form the feeders to the lakes and rivers, and which, percolating through the porous rocks and earth, issue as springs along the valleys. Some special sug gestions, however, relative to the selection of a potable water is advisable in this connection. In the open country water reaches the ground in a fairly pure condition and by selecting a site isolated from the drainage of barnyards, house sewerage and fertilized gardens, an ex cellent quality of water may be obtained from a well. Extending the application to where the supply is for the use of a community, town or small city, subterranean reservoirs in which the great rain percolations are stored up, may be tapped by artesian wells and furnish an in exhaustible supply of pure water. In boring these wells, however, a thorough knowledge of the geological structure of the region is im portant (see ARTESIAN in order to avoid unsuccessful and costly boring operations, as well as to obtain a sufficient quantity of water free from sub-surface impurities. Waters percolating through or over the crevices of granite, gneiss, serpentine, trappean, mica-slate or silicious sandstone and drift formations, are usually quite pure, since the disintegrations of such formations are not soluble in pure water. On the other hand, limestones and chalks im part objectionable qualities. Carboniferous rocks arc often composed largely of mineral salts and the water penetrating such strata are of a briny nature and are wholly unfit for do mestic use. This is the case in the Kanawha Valley and in some parts of Ohio, West Vir ginia and the State of New York. In the bituminous limestones of the oil regions of Pennsylvania, the waters passing through those strata are saturated with petroleum compounds, while the dark waters issuing from the sulphur ous rocks of the Niagara group of the Ontario geological division carry a high percentage of sulphuretted hydrogen.
As the municipality requiring the water in creases in size, the quantity obtainable from a source of supply becomes more and more im portant. The per capita consumption varies greatly and very often quite unexplainably. Sec