As the period is now approaching when greater necessity exists for the filtration of water than during thewinter season, anything new on the subject deserves attention We learn by a late number of the London Engineer that A P Malard, of Paris, has recently secured a patent for the employment of prepared woolshearings as a superior material for the water to pass through to be filtered He employs any common filter, luch as the portable kind so well known in our cities, which have a perforated false bottom, or a supporting shelf of wire gauze on which the filtering material is laid The woolhearings employed by M Malard are prepared in such a manner as to render them very durable, and not so liable to rot as the fibrous filtering diaphragms commonly employed He first boils his woolshearings for one hour in a solution of alum and cream of tartar, then takes them out, and exposes them to the air until they are quite cold After this he boils them for an hour in a solution of nutgalls and acetate of iron, then in a weak solution of the carbonate of soda, after which they are taken out, washed perfectly clean, dried, and are ready for use by placing them in a stratum on the false bottom of the filter, and allowing the water to percolate through them into the recess below, when it is drawn off clear and limpid for domesti use As hard water cannot be employed for washing without wasting considerable soap, a simple method of rendering it soft will be useful to many of our readers Take about a pint of fresh slacked lime, stir it in a gallon of water, and allow the sediment to settle ; pour off the clear water, and bottle it tight for use, because if the air is not excluded, it will absorb carbonic acid from the atmosphere Half a pint of this lime water is added to a gallon of hard water, stirred, and the whole allowed to settle, after which the clear is filtered through a diaphragm of Canton flannel, and is ready fo use, being rendered quite soft Those who reside in limestone districts, whare the wells contain hard water, will find this method of treating it (the water) very useful for washing purposes If they wish to use this softened water for drinking purposes, a little lemon juice or cider added to it will greatly improve its taste In the magnesian limestone regions of Ohio, and other places, where the water of the wells, in warm dry weather, is liable to cause cramps and chills when drank, especially to strangers ; the method described for treating it will prevent such results The fresh slacked lime water unites with the carbonic acid of the lime in the hard water, and the whole lime held in solution falls down in the state of fine chalk, leaving the water clear and soft The oxalate of ammonia also softens hard water, but it is net so easily managed as the caustic lime It is made by saturating oxalic acid (a poison) in liquid ammonia, and for this purpose the oxalic acid should be ground fine, and stirred among the ammonia with a glass rod A quart of the oxalate of ammonia will soften thirty gallons of hard water It is stirred among the water, the sediment allowed to settle, and the clear filtered For drinking purposes, this water also requires a little lemon juice or cider to render it pleasant to the taste Impure water is ftentimes the cause of disease The impurities consist either of organic or inorganic substances It is believed that the foregoing processes are capable of removing both kinds of such impurities