$i% An Ejjaj' on Bleaching* 



the end of the cloth is then unloofed, and it is fixed on the 

 arms of one of the reels of another immerfing tub, and it is 

 then unrolled till the whole that was in the apparatus is 

 drawn out : the extremity of the laft piece is then placed in 

 fuch a manner as to pafs ov^r the feven rollers of the im- 

 merfing tub, as is feen in the fe&ion of that vcfiel, (fee 

 Plate II. fig. 3. given with Number XXXVIII.) in order 

 to expofe as much furface as poffible to the liquor ; and being 

 fixed to the fecond reel, the cover is carefully adjufted, and 

 the oxygenated liquor is introduced by means of a leaden 

 funnel which pafles through the aperture of the cover, and 

 which proceeds to the bottom of the tub, to prevent the acid 

 gas from being difperfed by agitation. Alter feveral wind- 

 ings, a little of the liquor is taken up to examine its degree 

 of exhauftion ; it is then drawn off, and the pieces being 

 taken out feparately, they are carried to fome ftream to be 

 well riiifed : they are next expofed on the grafs for three or 

 four days, at the end of which they will have aequired a 

 high degree of whitenefs. Jn the laft place, to terminate 

 the operation, they are made to pafs through very dilute ml- 

 ph. uric acid. 



This operation, which is very expeditious, will be fuffir 

 cient for linen and cotton cloth ; but if hemp, or linen cloth 

 fhouid retain a yellow tint, (till necefiarv to be deltroyed, a 

 fecond alkaiino-cauftic vapour bath, and two or three days 

 on the grafs, will be futficient. to give them the requifite de- 

 gree of whitenefs. 



For ble tehiiig thread as well as hofiery, and the like, an 

 apparatus furnifhed with frames may be employed, (Plate V. 

 fig. 2. and 3.) following the fame procefles as for ftutfs. The 

 frames (fig. 3.) keep thete articles at a fuffieient diftancefroin 

 each oiher to make them be penetrated by the fleam in every 

 part; bjut as they cannot be lowered into the ley to moiften 

 them, as is done with ftufis, by means of cranks and rollers, 

 the 0; ^rdion is (topped at the end of two hours ebullition. 

 The upper frame is then well drenched with ley, which,, 

 oozing through, fuceeflively moiftens the articles placed on, 

 the lower frames. The ebullition is again begun, and con- 

 tinued for about four hours. The immerfion is performed 

 in an apparatus fimilar to that of Rupp, in which the thread 

 and hofiery are fufpended to the upper end of the reel, which 

 in this cafe Hands vertical, to renew, by a rotary motion, 

 their furfaccs of contact, and expofe them to the action of 

 the acid. After immerlion they are r'mfed ; they are then ex- 

 pofed on the grafs as in the preceding operation, and they 

 are made to pais through dilute fulphuric acid, 



fa 



