S2§ }7ew Method of Bleaching 



communication between the steamihg- kettle an5 steaming 

 ¥at; the former, which contains s«me water or aqueous solu- 

 tion, being kept at a proper heat by means of a fire put under 

 it, and the latter having previously its cover fitted on steam- 

 tight. The steam is thus, as it were, pent up in the kettle 

 and vat, and made to act with any pressure that may be de-^ 

 tired, or that the strength of the vessels may be able to sustain. 

 To secure the safety of the people employed, the apparatus 

 ought always to be furnished with a safety-valve, attached to 

 any part of the steaming-kettle or of the steaming-vat, or of 

 the tube of communication, that, when the elastic force of 

 the inclosed steam reaches a determined point, the valve may 

 open of itself, and allow a portion of it to escape. By this 

 process the goods can be heated considerably above the boil- 

 ing point; a circumstance that adds so much to the dissolving 

 power of the alkaline or soapy or other lye, that the quantity 

 left in the goods after draining, as before described, is found 

 sufficient to dissolve and discharge by one steaming as much 

 of the resinous, gummy, or other impurities fiom the goodsi 

 under process, as could have been discharged by a long boiling 

 of the goods in the lye itself, as is the usual practice ; and by 

 this means a great saving is made in the alkalies and other 

 ingredients employed for whitening the goods. For in the 

 common method the colouring matter, as discharged from 

 the fibre or texture of the goods, is diffused throughout the 

 whole lye ; which soon renders it so foul, that it is obliged to 

 be changed long before it has become saturated with the sub- 

 stances or matters on which it exercises its power. But by 

 this method there is no more lye employed for one steam- 

 ing than what is sufficient merely to impregnate the goods 

 thoroughly; and the alkali, thus deposited in the texture or 

 fibre of the goods under process, is more or less disengaged 

 from the said texture or fibre by the action of the steam, and 

 is found at the bottom of the steaming-vat, of a dark colour, 

 occasioned by the matters it has dii^solved and carried down 

 with it. The steaming-vat miay be very commodiously freed 

 from this deposit by a common stopcock, or even a plug, at 

 or near its bottom, to be opened as often as may be neces^sary. 

 The sam« end ia also effected by using only a deep boiler 



with 



