[ The impurity of the Louisville water, so I evident to a stranger who uses it for the first time, and so clearly demonstrable by a very simple chemical analysis, is also observed when an attempt is made to wash with it, especially with soap. The attempt is a very disagreeable one to a person accustomed to pure or soft water. It is true that this water is rendered somewhat softer bv boiling, which causes it to deposit some ot its lime and magnesia ; yet the amount of soap annually decomposed and wasted, in the effort to wash in the hard water, would be found on calculation to be no small item of expenditure. Its dissolved, earthy salts cause it to form a thick incrustation in the steam boilers in which it is used, which retards the action of the heat of the furnace, causes the more rapid burning of the bottom ot the boiler, and thus renders probable more frequent bursting. For the same cause it is unfit for the use of the brewer, and for many uses to which water is applied in various manufacturing processes.— [Louisville, Ky., Courier. [Magnesia in drinking water is unwholesome ; it is believed to be the cause of cretinism in some parts of Switzerland and England. Lime water—carbonate of lime, is a soap eater. Hot slacked lime, strange as it may seem, cures the evil. A very small portion is required. It is now used in Manchester, England, in all the bleaching and calico print works, to make hard lime water soft. The people in Louisville will find a full account of the processes of making hard water soft on page 347, Vol. 7. Scientific American.