BLEACHING. 



BLEACHING. 



190 



on the old process would have occupied weeks of exposure upon a 

 hundred acres of land. 



Chlorine was first used ill the state of simple solution in water; 

 afterwards, in order to lessen its destructive action when used in too 

 concentrated a state, it was proposed to add potash to it. This com- 

 pound however was not found to answer the purpose ; but in the year 

 1798, Mr. Tennant of Glasgow took out a patent for a liquid compound 

 of chlorine and lime. This patent being set aside, he took out another 

 for impregnating dry hydrate of lime with chlorine gas ; this inven- 

 tion was not contested, and the chloride of lime, generally known 

 by the name of bleaching-powder, is now almost universally employed, 

 especially in the bleaching of cotton : it is a compound which answers 

 the purpose with economy, celerity, and safety. 



The colouring matter of cotton, llax, and hemp, is insoluble in water, 

 and appears to be of a resinous nature : it is partially dissolved by 

 heated solutions of lime and potash, or soda ; and by their use, and the 

 application of a solution of bleaching-powder and dilute sulphuric acid, 

 the colouring matter which is not dissolved is destroyed. Cotton is 

 more readily bleached than flax or hemp, and these more readily than 

 wool : indeed this last-mentioned substance, as well as silk, is gene- 

 rally bleached by the fumes of burning sulphur, or sulphurous acid 

 gas, after they have been properly cleansed. Straw and feathers are 

 also bleached by sulphurous acid gas. Wax is generally deprived of 

 its colour by mere exposure to air, light, and moisture. 



The bleach- works of Lancashire and Glasgow are among the largest 

 and finest of our manufacturing establishments; exhibiting mecha- 

 nical contrivance, chemical knowledge, and those powers of com- 

 bination and classification so remarkably developed where many 

 hundred persons are employed in one establishment. The following is 

 an outline of the series of processes, as conducted on a large scale : 

 SupiKtfing ordinary cotton-cloth or calico is about to be bleached, the 

 ' pieces,' as they are called, usually of twenty-eight yards each, are 

 sewn or tacked together into a web six or eight mifos in length ; which 

 web, connected at the two ends, becomes practically endless, like the 

 travelling-web of a printing machine, or the wire-web of a paper- 

 making machine. This web is passed over a heated cylinder, to singe 

 off the loose fibres ; it is then washed to remove the flax or dressing ; 

 it is next exposed for eight or ten hours to a hot solution of lime ; and 

 is again washed to remove the lime which may adhere to the fibres. 

 The long web of cloth is then steeped in water containing a little 

 sulphuric acid ; after which it is washed a third time in clear water. 

 Three of these long webs, making twenty-four miles in length of 

 calico, are boiled in a solution of soda, then washed, then passed 

 through a weak solution of bleaching-powder, and then allowed to 

 remain in a heap for the chloride to act on the fibres. Next come, in 

 succession, a second dip into dilute acid, a fifth washing, a second 

 application of soda, a sixth washing, a second application of bleaching- 

 fiolution, a third dip in the acid, and a seventh washing thus showing, 

 in a striking degree, how complex are the processes which modern 

 ingenuity enables the manufacturers to carry on at a very cheap rate. 

 The bleached calico is washed in hot water, and squeezed between 

 rollers; the web is separated into its component pieces; and each 

 piece is folded and dried. It may be remarked that the bleaching of 

 other kinds of cotton goods, and of yarn and thread, although involving 

 minor peculiarities, may be understood from this description of the 

 bleaching of calico and of cotton for printed dresses. 



Not a year elapses without developing some new processes or 

 apparatus for bleaching ; many of these novelties are made the subjects 

 of patents, though not always with advantage to the patentees. One 

 patent, by M. David, of Paris, relate* to a peculiar mode of applying 

 chlorine to the goods to be bleached. The chemical materials for making 

 the gas are to be provided by the bleacher ; and as the gas is generated, 

 it i conveyed by pipes into a close chamber. The woven goods are to be 

 laid on perforated shelve* in this chamber, and thus be acted upon by 

 the chlorine. A fan or blowing-machine is used to clear the chamber of 

 gas before the goods are removed from it ; and glass windows are 

 provided to the chamber, through which the process may be watched. 

 A second patent relates to a peculiar way of conducting the cloth into 

 and through a vessel of liquid, and beating it on both surfaces imme- 

 diately after it* immersion, in order that the fibres may become 

 impregnated and the superfluous liquid be driven off. Another patent is 

 for a peculiar mode of causing the woven goods to pass over two 

 rollers, one above the other, in a close chamber filled with chlorine or 

 sulphurous acid gas. Passing over many inventions of varied character, 

 we may advert to a dash-wheel invented by Mr. Wallace of Glasgow, 

 .ind brought largely into use in 1857. The dash-wheel, generally used 

 by bleachers, dyers, and calico-printers, is a hollow cylinder or box, 

 made* to rotate with great, rapidity, so an to wash very speedily 

 any woven goods immersed in water within it. Now Mr. Wallace's 

 plan is to render the daub-wheel more extensively available than here- 

 tofore as a bleaching and cleansing apparatus. The wheel is mounted 

 on a hollow shaft, by which it is put in communication with a steam- 

 pipe. Steam, instead of water, is admitted through perforations in the 

 shaft, into the several compartment* into which the interior of the 

 wheel ii subdivided. Acids, alkalies, or soaps may be placed in cisterns 

 above the wheel, in solution with water ; and may be made to descend 

 through pipes into the hollow shaft. By this means, any admixture or 

 variety of chemical agents, whether for washing or for bleaching, may 



be admitted into the wheel, and made to act upon the woven cotton 

 goods placed in the several compartments. The liquid, when the 

 washing or bleaching is effected, finds egreas by holes in the circum- 

 ference of the wheel. A dash-wheel of six feet diameter, on this 

 construction, is estimated to make twenty-four revolutions per minute; 

 one of nine feet diameter, sixteen revolutions the velocity of the 

 circumference being in each case about four hundred and thirty feet 

 per minute. A steam-engine of about five-horse power, with steam of 

 three or four pounds per inch above atmospheric pressure, would 

 produce this degree of revolving action. 



With respect to the theory of bleaching it may be observed, that the 

 action of lime and the alkalies, potash and soda, appears to be that of 

 mere solvents ; they probably dissolve the colouring matter without 

 effecting much alteration in its properties. The actions of atmospheric 

 air and chlorine seem to be similar to each other, and very different 

 from that of lime and the alkalies. The oxygen of the air aided by the 

 action of light and moisture apparently combines with and destroys 

 the colouring matter; while the chlorine, decomposing the water 

 which is present, forms muriatic acid with the hydrogen of the water ; 

 another portion with its oxygen probably giving rise to a compound of 

 easy decomposition, the nascent oxygen of which acting like that of 

 the air, though more powerfully, produces the same oxidising effect 

 upon the colouring matter, but more perfectly, and in a much shorter 

 period. That water is necessary to the action of chlorine upon 

 vegetable colouring matter, is shown by immersing dry colouring 

 matter in the dry gas, in which case no decoloration whatever is 

 effected, but it ensues immediately on the introduction of water. The 

 bleaching of rags for paper-making is effected by the agency oi,chlorine. 

 Paper ako, when written on or printed, may be bleached by the same 

 means. There are some operations in which the removal of colour is 

 hardly referable to the process of bleaching ; such for example as the 

 decoloration of sugar, which derives its colour, not from any natural 

 cause, but the partial decomposition effected by heat. This is removed 

 by what is usually termed animal-charcoal or ivory-black; which 

 powerful decolorant is also used in some chemical operations for the 

 same purpose. 



We must now notice the proceedings connected with bleach-works 

 regarded as factories, subject to legislative control. 



An opinion has during several years prevailed among many persons 

 conversant with the manufacturing establishments of the North, that 

 when spinning and weaving mills were placed under the operation of 

 the Factory Act, in relation to the employment of women and children, 

 bleach-works ought to have been included, as well as print-works and 

 dye-works. The manufacturers, on the other hand, have all along con- 

 tended that there was no need for such an' extension. The attention 

 of Parliament having often been called to this subject by the upholder* 

 of the Factory Act, at length, in 1854, the Government appointed a 

 commission " To inquire how far it may be desirable to extend the 

 provisions of the Acts for the better regulation of Mills and Factories 

 to bleaching works ; " and Mr. Seymour Tremenheere, one of the 

 factory inspectors, was appointed commissioner. The commissioner 

 presented his report in June 1855. It is necessary to mention that 

 this inquiry arose out of a movement which was marked by much 

 collision of opinion. Early in 1854 the Earl of Shaftesbury brought 

 into the House of Lords an " Operative Bleachers Short Time Bill," 

 intended to restrict the labour of females and young persons in bleach- 

 and dye-works to ten hours and a half per day. He was supported in 

 this by the operatives themselves. There was also a petition sent to 

 Parliament signed exclusively by members of the clerical and medical 

 professions, 128 in number, all resident in or near Manchester. The 

 petition declared that females and young persons often worked from 

 fourteen to twenty hours a d;iy in bleach- and dye-works, and sometimes 

 for days and nights consecutively without intermission, except for 

 meals ; and they insisted that nothing but legislative interference 

 could remedy the evil. The master bleachers contested these state- 

 ments, in a memorial addressed to Lord Palmerston. They did not, 

 it is true, deny that the hours of work were sometimes very long ; but 

 they asserted that this was a necessary condition of certain peculiarities 

 in the trade. " The trade of bleaching and finishing is difficult to 

 manage ; and it differs from other branches of the cotton trade in this 

 that the supply of goods to be bleached fluctuates. During some 

 portions of the year we are only partially employed, whilst at other 

 times we have more work to do than could be accomplished if the 

 hours of labour were restricted." They declared that the greatest care, 

 industry, and skill are required to enable English bleachers and dyers 

 to compete with those of the continent and of America ; and that any 

 legislative enactment which increased the working expenses would be 

 disastrous to the bleachers, who had no less than two millions 

 sterling of capital sunk in the trade. The Earl of Shaftesbury's Bill, 

 though passed by the Lords, was checked in its progress through the 

 Commons by the lateness of the session ; but the discussions in both 

 Houses led to the appointment of the commission above adverted to. 



Mr. Tremeuheere, after visiting most of the principal bleach works 

 in the United Kingdom, classified the processes into three groups 

 preparing, bleaching, and finishing. The preparing includes the 

 marking with the needle the pieces of cloth with the initials or private 

 mark of the owner; sewing or pasting the ends of several pieces 

 together, to facilitate the subsequent processes; and dressing or 



