BLEACHING.

143

expense of one extra drying can be afforded, the process might be very much improvedby steeping the brown calicoes for thirty or forty hours before singeing, because this wouldseparate much of that impurity which usually becomes fixed in the stuff’ on its being pass-ed over the hot cylinders. When the pieces have been thus singed, steeped, and pressed,they are boiled four times, ten or twelve hours at each time, in a solution of caustic pot-ash, of the specific gravity of from 1-0127 to 1-0156, washing them carefully and thorough-ly in pure water between each of these boilings. They are then immersed in a solution°f the chloride of potash, originally of the strength of T0S25, and afterwards reducedtvith twenty-four times its measure with water.

. When the preparation is good, these proportions will whiten cotton goods completely in^"ht hours. In this steep they are, however, generally suffered to remain twelve hours.It has been supposed that the common bleaching liquor (chloride of lime) cannot, without■njury, be substituted for chloride of potash, but I believe this to be a mistake.

Some printers take the pieces from this solution, and, while wet, lay them upon theSjass, and there expose them to the sun and weather for two or three days. They archence removed to the sours, made of the specific gravity of about 1-0254 at the temper-ture of 110° of Fahrenheit. In bleaching common goods, and such as are not designedbest printing, the specific gravity of the sours is varied from that of T0146 to that1-0238, if weighed when they become of the temperature of the atmosphere. In theseej are suffered to lie for five or six hours, after which they are taken to the dash-wheelna washed thoroughly. When this operation is finished, they are submitted to four moreoffings as before, with a solution of caustic potash; taking care to wash well betweench of these boilings. Sometimes pearl-ash, made caustic, is used for the last of theseth 1111 ^, lest the sulphur, which always exists in the potashes of commerce, should impairbef W ''* tes - They are next immersed in the diluted chloride of potash, of the strengthp 0 —o mentioned; after which they are well washed in pure water, and then winchedof l 1 * atl h° ur i n common sours. The last process is that of careful washing in plentyin th eaa .?-‘te r » a ^ er which they are not put into the stove, but are immediately hung upe airing sheds to dry gradually. The water must be good, and abundant,of e number of operations, as here described, is great; but I know of no other modeSeas ° ce< ^ Ul .' e by which perfect bleaching is so likely to be effected at all times and in allof d . ns ’. without disappointment. It must here be remarked, that, for the best purposesc* it would not be sufficient to take goods which have been bleached in the

sited ' 0I1 p Vay an< ^ finish these by the better process; because the sulphate of lime depo-a n r j tae doth by that operation will be apt to spoil them for madder colors; at least,$ fr- r w '*° * s cnHous in his business would hesitate to work up such cloth.

°fboth ° r Bowking .—This is one of the most important operations in the bleachingriecl on . CC ! t,:on and linen goods. There are several methods whereby this process is car-tnethocl’ p of these we shall select only two, distinguishing them as the old and newas befor i ' c H' n =- In the former way, the cloths have been steeped in the alkaline ley,Vat , or ^ ? escr ibed, and afterwards well washed, are regularly arranged in a large wooden" , ii>ch is n GVe ’ a b°il er °f sufficient capacity is then filled with caustic alkaline ley,Up 0Il ^ heated to the temperature of blood. The boiler is then emptied by a stop-cockhcniaineff laens — the kieve, until they are covered with the liquor. After havingkieve ini ° n d—h f° r some time, it is run off by a stop-cock, at the bottom of theby a p Un .° nnlcon boiler sunk in the ground, from whence it is raised into the boilerUpon the The heat is now elevated to a higher temperature, and the ley again runficscribeij ■ ^°°^ s the kieve; from whence it is returned into the boiler, as before"Utaline L • t,lese operations are continued, always increasing the heat, until thewhich i s ls completely saturated with the coloring matter taken from the cloth,causticity- ° wn ^ its having acquired a completely offensive smell, and losing its

!° a ttcr, we^sh < J. ons d er the effect which heated liquids have upon colored vegetableincrease -t? 1 see the propriety of the temperature of the alkaline ley being gradually. ae coloring W *? en vegetable substances are hastily plunged into boiling liquids,ato the m j, • er > in place of being extracted, is, by this higher temperature, fixed° or of vegemy on . Principle that a cook acts in the culinary art, when the greenth c tlley are p.? 5 . n la,;ent I e . t Ito be preserved: in place of putting them into water when,. e former case Pi )ac < un til the water is boiling; because it is well known that, inOn S fk re not infuse"? " re -t n color would be entirely extracted, whereas, when the vegeta-the same prim-; ! lntl th e water is boiling, the color is completely preserved or fixed.rl v ract ‘ Ve and coin?*’ w “ en the tempeiature of the alkaline ley is gradually raised, theWh' e "k'"hen the lev — atter ! s more effectually taken from the cloth; and the case isConrt ** as been so unfn | S at H' e boiling temperature : so much so, that linen

■ip. white. r una te as to meet with this treatment, can never be brought to a

when the alkaline

ey I* saturated with coloring matter, it is run off as unfit for