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purposes when a boiling temperature is kept up for the last thirty minutesof that period. It has been found that when the goods are left in the dye-beck for eight hours at 50° C., more colouring matter has been extracted (themadder more exhausted) than when the fabrics are only kept in the beck forthree hours and ebullition resorted to. This observation applies to Alsace aswell as to Avignon madder. When the dyeing process is continued for morethan six hours the colours produced stand clearing* (avivage) less well thanwhen the time has been shorter. Since the quantity of water is of considerableinfluence, this point was particularly investigated by M. Schlumberger, and asresult of his researches he concluded that 1 part of madder to 80 of waterwas the best. When less water is taken, say 20 parts to 1 part of the madderthe colours produced are less fast. We have to observe here, however, thaton the large scale these proportions are not rigorously adhered to, and that inorder to saye the cost of fuel and the number as well as the size of dye-becksmore concentrated baths than 1 to 80 are used.

As regards the quality of water we have, in this instance, chiefly to considerthe effe&s of the lime salts it may contain, and especially the carbonate ofthat base. Taking Alsace madder as an example, that substance is acid, andrequires, in order to produce fast colours, the addition of some chalk to thewater in the dye-beck. Hence a calcareous water will not give rise to anyperceptible loss of colouring matter, but if Avignon madder be used, a sub-stance of which we know already that it contains a certain quantity ofcarbonate of lime, any addition thereto to the water used for dyeing willcertainly cause a serious loss of dye material. It is clear, therefore, that inlocalities where the water at hand may happen to contain lime salts (car-bonate or sulphate) to any large extent it will be best to purify it by con-venient means or to use for filling the dye-becks the condensed steam fromthe boilers.f According to M. Schlumberger it is best to heat the contentsof the dye-beck to 6o° before the goods are entered, but on the large scale thisarrangement would cause irregularities in the dyeing, since at that tem-perature the a&ivity of the bath is already considerable, and, moreover, ex-perience has proved that the shades obtained by immersing the fabrics in thebath at a too high initial temperature do not stand clearing so well as whenentered at lower temperatures, viz., 20°, 30, or 40°. There is.some differenceof opinion as regards the highest temperature to be applied in order to utiliseall the colouring matter. According to some persons the temperature shouldbe raised to the boiling-point, but according to the author just named a tem-perature of 50° for Avignon madder and 8o° for Alsace exhausts these sub-stances as completely as a temperature of 95 0 , provided the dyeing be pro-longed for eight hours. Although a boiling heat favours the fixation of the

* There is, unfortunately, too close a similarity in the English words cleansing and clearing,and for that reason we have added (avivage); be it understood that cleansing is an operationwhich takes place before the dyeing process, and is named in French dtgommage and bousage ;though the latter term,as can be inferred from our foregoing pages, rather applies to dunging,clearing (avivage ) is an operation which takes place after dyeing, and is chiefly intended—(1) for the washing away of dirt and superfluous colouring matter; (2) for bringing out thepeculiar brilliancy of the colours. The process of clearing will be fully detailed after we havedescribed the dyeing.

+ Since in printing works, just as in sugar refineries, much steam is used for heating pur-oses, and circulates in piping, it is not difficult to collect a sufficient quantity of pure water.