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DYEING AND CALICO PRINTING.

To enter into particulars concerning the analysis of water or the detedtionof the various salts which it may contain would consume too large a portionof our space; readers requiring further information on the subjedt will find itin works on analytical chemistry: it is here intended briefly to point out thedifferent adtions of the carbonate and sulphate of lime in dyeing. Both areinjurious to bright colours, but not so to dark or sombre hues, unless presentin very large quantity; carbonate of lime is even considered rather ad-vantageous in madder dyeing, especially with certain kinds of madder, andground chalk is frequently added to the water before using it, to make up anydeficiency. Sulphate of lime in any quantity is injurious in dyeing withmadder or with any dye procured from wood, causing waste of colouringmatter with inferior results. The produdtion of good brilliant light shades isincompatible with the use of water containing sulphate of lime. Magnesia inthe state of chloride or sulphate does no harm provided it be not easilyconvertible into carbonate by boiling, which can readily take place should muchcarbonate of lime be present in the water; but if it should exist as car-bonate or be converted into it during dyeing it is very detrimental, as it com-pletely prevents the dyeing of certain colours and spoils the appearance ofothers. Madder, when mixed with one-fiftieth of its weight of calcinedmagnesia will not dye at all, and is spoiled by the addition of one part per cent.In the north of England it is sometimes present in quantity sufficient to affedtmadder colours; however, it is seldom present in water in sufficient quantity tobe injurious.

Iron is found in almost all natural waters, but not usually in verylarge quantities, except in mineral waters. As has already been stated, itgenerally occurs as carbonate of the protoxide held in solution by excess ofcarbonic acid. Its presence, whether in large or small quantities, is veryinjurious to dyeing operations, and we therefore give a good practical test forits detedtion. If a single drop of tindlure of logwood or strong logwoodliquor be added to a wineglass of water perfedtly free from iron, it will assumea sherry or claret colour, according to the quantity of lime present; but shouldthe water contain iron, it will turn blue, blue-black, and finally inky-black, inproportion to the amount of that metal held in combination. This testrequires to be examined immediately, for if the glass vessel in which it ismade be left exposed to the air the logwood turns darker, and might perhapsbe supposed to indicate iron in cases where none existed. Another precautionis necessary: the water to be tested should be freshly drawn, for should ithave been standing for some time, even in well closed bottles, the iron is pre-cipitated as insoluble oxide, in which case the change of colour by logwoodno longer takes place. The influence of water impregnated with iron upondyeing is very marked—pinks become drabs, and reds are turned into dullbrowns and chocolate colours, whilst, if the quantity of iron present be large,it combines with the cplouring matters, and the cloth receives none of them,or only a small proportion. Fortunately for the dyers, the simple adtion ofthe oxygen of the air readily decomposes the salts of the protoxide of iron asmet with in natural waters and turns them into peroxide of iron, so thatwater containing that metal need not necessarily be rejedted for dyeingpurposes. Where larger quantities of iron are present the same effedt may beproduced by aerating the water, and if possible heating it by means of waste