586 BLEACHING. 



Pleach ing, are further prepared for alkaline substances acting soured about the middle of the bleaching process, it Bleaching. 



*^-v-~~ upon them, and fitting them for the reception of has a considerable effect in hastening forward the r ' 



oxygen in subsequent immersions. We have already goods to a complete white, and, in consequence, ear- 

 described the method of preparing the oxymuriatic ly souring has been adopted by the best practical 

 acid with potash at some length, and h?ve now only bleachers. 

 to remark, that the common way of diluting it for 



use, is by adding it in sufficient quantity to pure wa- Having made these preliminary observations with 

 ter, until the specific gravity of the mixture k 1005. regard to the method of applying the various articles 

 The linens, after being clftl washed, are steeped in used in bleaching linen cloth,' we shall now bring the 

 it lor twelve hours, then drained, and washed for be- whole into one point of view, by detailing the con- 

 ing further bucked or boiled. ncction of these processes, as carried on at a bleach- 

 field which has uniformly been successful in return- 

 Sect. V. On Souring. ' n ? tne c ' otn f a good white, and otherwise giving 



satisfaction to their employers ; and we shall only 



n souring. Souring is in general the last or finishing process previously remark, that we by no means hold it up 



in bleaching, as afterwards the linens are only further as the best process which may be employed ; as every 



washed in spring water, in order to their being blued experienced bleacher knows, that processes must be 



and made up for the market. varied, not only according to existing circumstances, 



In preparing the sour, into a large fir tub, lined but also according to the nature of the linens opera- 



with lead, as much sulphuric acid is added to water ted upon. 



as will give it the acidity of strong vinegar. The In order to avoid repetition, where washing is 



. acid and water must be well mixed together before mentioned, it must always be understood that the li- 



immersing the linens, which are generally steeped in nen is taken to the wash stocks, or dash wheel, and 



it for twelve hours, then drained, and washed in pure washed well in them for some hours. This part of 



water. The operation of washing must be paid par- the work can never be overdone ; and on its being 



ticular attention to after this process ; were any of properly executed between every part of the bucking, 



the acid to remain in the goods, and to be dried into boiling, steeping in the oxymuriatic acid, and sour- 



them, they would infallibly rot, although the acid ing, not a little of the success of bleaching depends, 



has no such effect upon them while they are kept By exposure is meant, that the linen cloth is taken 



wet. and spread upon the bleachgreen for four, six, or 



What effect souring has in bleaching, neither the eight days, according as the routine of business calls 



practical bleacher nor the chemist have attempted to for the return of the cloth, in order to undergo fur- 



determine. It is certain, that, from frequent use, it ther operations. 



completely loses its acidity, and remains an inert sub- " A parcel of goods consists of 360 pieces of those 



stance, similar to a neutral salt. Some suppose that linens which are called Britannias. Each piece is 



it is saturated with the remaining alkali which has 35 yards long, and they weigh on an average 10 lbs. 



not been completely washed from the goods ; with each : the weight of the parcel is, in consequence, 



iron, which is said to be a component part of all ve- about 3600 pounds avoirdupois weight. The linens 



getable substances ; or with earth, which is likewise are first washed, and then steeped in waste alkaline 



said to be contained in them. Whatever may be in ley, as formerly described under these processes ; 



these conjectures, it is certain, that when linens are they then undergo the following operations :. 



1st, Bucked with 60 lt> pearl ashes, washed, exposed on the field. 



2d, Ditto .... 80 . . . do, ... do. . . do do. 



3d, Ditto ... 90 . potashes, . . do. . . do do. 



4th, Ditto ... 80 ... do. ... do. . . do do. 



5th, Ditto ... 80 ... do. ... do. . . do do. 



6th, Ditto ... 50 ... do. ... do. . . do do. 



7th, Ditto ... 70 ... do. ... do. . . do do. 



8th, Ditto ... 70 ... do do. . . do do. 



9th, Soured one night in dilute sulphuric acid, washed. 

 10th, Bucked with 50 lb pearl ashes, washed, exposed on the field. 

 11th, Immersed in the oxymuriate of potash 12 hours. 

 12th, Boiled with 30 lb pearl ashes, washed, exposed on the field. 



13th, Ditto ... 30 .... do. . . do. ... do do. 



14th, Soured, washed. 



The linen3 are then taken to the rubbing board, 

 and well rubbed with a strong lather of black soap, 

 after which they are well washed through pure spring 

 water. At this period they are carefully examined, 

 and those which are fully bleached are laid aside to 

 be blued and made up for the market ; while those 

 which are not fully white, are returned to be boiled 

 and steeped in the oxymuriate of potash, and soured, 

 until they are fully white." 



By the above process, 690 pounds weight of al- 

 kali is taken to bleach 360 pieces of linen, each piece 

 consisting of 35 yards in length ; so that the expen- 

 diture of alkali woidd be somewhat less than 2 lb 

 for each piece, were it not that some part of the 

 linens are not fully whitened, as above noted. Two 

 pounds of alkali may therefore be stated as the ave- 

 rage quantity employed for bleaching each piece of 

 goods. 



