578 



BLEACHING. 



Bleaching. w j tn t he colouring matters with which cotton and li- 

 nen manufactures are stained ; and that, by a proper 



use of the alkalies, along with the oxymuriatic acid, 

 these colouring matters could be removed, and the 

 goods rendered white, in a space of time almost in- 

 stantaneous, when compared with the former method 

 of bleaching. 



Upon these discoveries the present improved state 

 of bleaching is founded. And, when the vast ex- 

 tent of the cotton and linen manufactures of Great 

 Britain and Ireland is considered, every improve- 

 ment in it must be admitted to be of the highest na- 

 tional importance. To exhibit the present state of 

 this art, by giving a succinct statement of the late 

 improvements, is the subject of th.: following article, 

 which, for the sake of method, shall be arranged 

 under the following chapters, viz. : 1. A description 

 of the machinery used in the modern bleachfields. 



2. Of the detergent and other substances used. 



3. An account of the manner in which these sub- 

 stances are applied. 



CHAP. I. 



Of the Machinery used in Modern Bleaclifields. 



Machinery The machinery and utensils used in bleaching are 

 used in various, according to the business done by the 

 Bleaching, bleacher. Where linen or heavy cotton cloths are 

 whitened, and the business is carried on to consider- 

 able extent, the machinery is both complicated and 

 expensive. It consists chiefly of a water-wheel suf- 

 ficiently pqwerful for giving motion to the wash 

 stocks, dash wheels, squeezers, eve. with any other 

 operations where power is required. 



Figures 6. and 7. Plate LV. represent a pair of 

 wash stocks. AA are called the stocks or feet. 

 They are suspended on iron pivots at B, and re- 

 ceive their motion from wipers on the revolving shaft 

 C. The cloth is laid in at D, and, by the al- 



Wash 

 stocks. 

 Plate 

 l.V. 

 Fie. 6, 7. 



ternate strokes of the feet, and the curved form of Bleaching, 

 the turnhead E, the cloth is washed and gradually ' "v ' 

 turned. At the same time, an abundant stream of 

 water rushes on the cloth through holes in the upper 

 part of the turnhead. Wash stocks are much used 

 in Scotland and in In/land. In the latter country, 

 they are often made with double feet, suspended 

 above and below two turnheads, and wrought with 

 cranks instead of wipers. Wash scocks, properly 

 constructed, make from 24 to 30 strokes per mi- 

 nute. 



This mode of washing is now entirely given up in p^j, 

 Lancashire, where a preference is given to what are wheel-. 

 called dash wheels and squeezers. The dash wheels 

 are small water wheels, the inside of which are di- 

 vided into four compartments, and closed up, only 

 leaving a hole in each compartment for putting in 

 the cloth. There are, besides, smaller openiugs for 

 the free admission and egress of the water employed 

 in cleansing. The cloth, by the motion of the 

 wheel, is raised up in one part of the revolution of 

 the wheel ; while by its own weight it falls in an- 

 other. This kind of motion is very effectual in 

 washing the cloth, while, at the same time, it doe* 

 not injure its strength. This plan, however, where 

 the economy of water is an object of any importance, 

 is very objectionable, because the wheel must move 

 at by far too great a velocity to act to advantage as 

 a water wheel. 



Fig. 1. Plate LV. represents a dash wheel con- Plate 

 structed to receive its motioa from a shaft A, con- LV. 

 nected either with a water wheel or steam engine. "&' ' 

 The dash wheel, CD, is fixed on a separate axis, 

 2nd is engaged or disengaged from the rest of the 

 mill work by a very simple contrivance. On the 

 end of the the shaft AB is a face wheel FG, with 

 projecting teeth made to correspond with those of a 

 similar face wheel HI. The axis of the dash wheel 

 is made moveable endways ; by sliding it forward, 

 the teeth lay hold of one another, and the dash 



failing in that, a patent right, for a new method of bleaching, which they professed would shorten the process, and reduce it 

 to a lew hours. Mr Watt, however, having been made acquainted with Bcrthollet's discovery, and having actually applied 

 it in practice to the whitening of .500 pieces of cloth, resisted this monopoly ; and was joined by Mr Cooper and Mr Henry 

 of Manchester, both of whom had also been successful in their attempts to apply the acid to the bleaching of cotton goods, 

 though their experiments were conducted on a smaller scale. The opposition was effectual, and the foreigners were foiled in 

 their attempt to obtain a patent. 



Owing most probably to his distance from the seat of the cotton manufacture, Mr Watt did not himself embark in the 

 practice of bleaching. Mr Cooper, however, formed an establishment for the purpose of applying Mr Bcrthollet's discovery ; 

 and Mr Henry not only engaged in a similar undertaking, but gave, to some of the principal bleachers in this country, the 

 Krst Instruction! which they received resecting the new process. The method of the latter gentleman at first consisted, 

 sometimes In immersing the goods in a watery solution of the gas, or in an alkaline ley impregnated with it, and sometimes 

 in exposing the goods, previously moistened with water, to the action of the gas itself. Soon afterwards, he made a further 

 improvement in substituting lime for alkali, as a means of condensing the oxymuriatic acid gas. An air-tight chamber 

 prepared, on the floor of which rested a stratum of lime and water, mixed together to the consistence of cream. Through 

 ibis the goods were passed by means of a wince; and the chamber being Blled with gas, the goods were alternately exposed 

 to the lime liquor, and to the acid vapour. Thus an oxymuriate of lime was formed upon the cloth, which, after a sufficient 

 continuance of the operation, was taken out, and exposed to the usual processes of washing, &c. 



A very essential improvement in the application of lime was, some years afterwards, discovered by Mr Tennant of Darn- 

 ley, near Glasgow, and WSJ secured to him by a patent, dated January 30, 1798. It consisted in effecting a combination 

 ..-id with lime, in a separate vessel, Containing lime suspended in water by mechanical agitation. The re- 

 dundant Inne was allowed to subside, and the clear liquid, a solution of oxymuriate of lime, applied, property diluted, to 

 purpose of bleaching. It is remarkable, that this combination, even alien the oxymuriatic acid is perfectly neutralized, has 

 Mi ftmtl of bleaching iirhl or thin goods, though it is mvrh less active in disrhargins: torn vegetable colours. Hence this method 

 hai certainly a great advantage over all fvnmr ones, in the facility anil safety of in application, especially to cohnrtd good*, 

 which Would hi dischurpd by the contact of either the acid or of lime in an vnconibintd form. This patent has since been scl 

 . ion Oi a court of law, with what justice we do not pretend to decide. Mr Tennant, however, still retains 

 an exclusive right to a method, secure'd to him by a subsequent patent, of uniting the oxymuriatic acid with dry quicklime, 

 end thus rendering the bleaching salt portable to any distance in the form of a powder. Editor. 



