Volume 4, Slice 1 Part 15 (1/2)
The chief industries are coal-mining, iron-founding, pipe, fire-brick, chemical manure and bottle manufactures. In the vicinity is the beautiful old mansion of Stella, and below it Stellaheugh, to which the victorious Scottish army crossed from Newburn on the Northumberland bank in 1640, after which they occupied Newcastle.
BLAYE-ET-STE LUCE, a town of south-western France, capital of an arrondiss.e.m.e.nt in the department of Gironde, on the right bank of the Gironde (here over 2 m. wide), 35 m. N. of Bordeaux by rail. Pop. (1906) of the town, 3423; of the commune, 4890. The town has a citadel built by Vauban on a rock beside the river, and embracing in its enceinte ruins of an old Gothic chateau. The latter contains the tomb of Caribert, king of Toulouse, and son of Clotaire II. Blaye is also defended by the Fort Pate on an island in the river and the Fort Medoc on its left bank, both of the 17th century. The town is the seat of a sub-prefect, and has tribunals of first instance and of commerce and a communal college. It has a small river-port, and carries on trade in wine, brandy, grain, fruit and timber. The industries include the building of small vessels, distilling, flour-milling, and the manufacture of oil and candles. Fine red wine is produced in the district.
In ancient times Blaye (_Blavia_) was a port of the Santones. Tradition states that the hero Roland was buried in its basilica, which was on the site of the citadel. It was early an important stronghold which played an important part in the wars against the English and the Religious Wars. The d.u.c.h.ess of Berry was imprisoned in its fortress in 1832-1833.
BLAZE (A.-S. _blaese_, a torch), a fire or bright flame; more nearly akin to the Ger. _bla.s.s_, pale or s.h.i.+ning white, is the use of the word for the white mark on the face of a horse or cow, and the American use for a mark made on a tree by cutting off a piece of the bark. The word ”to blaze,” in the sense of to noise abroad, comes from the A.-S.
_blaesan_, to blow, cf. the Ger. _blasen_; in sense, if not in origin, it is confused with ”blazon” in heraldry.
BLAZON, a heraldic s.h.i.+eld, a coat of arms properly ”described” according to the rules of heraldry, hence a proper heraldic description of such a coat. The O. Fr. _blason_ seems originally to have meant simply a s.h.i.+eld as a means of defence and not a s.h.i.+eld-shaped surface for the display of armorial bearings, but this is difficult to reconcile with the generally accepted derivation from the Ger. _blasen_, to blow, proclaim, English ”blaze,” to noise abroad, to declare. In the 16th century the heraldic term, and ”blaze” and ”blazon” in the sense of proclaim, had much influence on each other.
BLEACHING, the process of whitening or depriving objects of colour, an operation incessantly in activity in nature by the influence of light, air and moisture. The art of bleaching, of which we have here to treat, consists in inducing the rapid operation of whitening agencies, and as an industry it is mostly directed to cotton, linen, silk, wool and other textile fibres, but it is also applied to the whitening of paper-pulp, bees'-wax and some oils and other substances. The term bleaching is derived from the A.-S. _blaecan_, to bleach, or to fade, from which also comes the cognate German word _bleichen_, to whiten or render pale.
Bleachers, down to the end of the 18th century, were known in England as ”whitsters,” a name obviously derived from the nature of their calling.
The operation of bleaching must from its very nature be of the same antiquity as the work of was.h.i.+ng textures of linen, cotton or other vegetable fibres. Clothing repeatedly washed, and exposed in the open air to dry, gradually a.s.sumes a whiter and whiter hue, and our ancestors cannot have failed to notice and take advantage of this fact. Scarcely anything is known with certainty of the art of bleaching as practised by the nations of antiquity. Egypt in early ages was the great centre of textile manufactures, and her white and coloured linens were in high repute among contemporary nations. As a uniformly well-bleached basis is necessary for the production of a satisfactory dye on cloth, it may be a.s.sumed that the Egyptians were fairly proficient in bleaching, and that still more so were the Phoenicians with their brilliant and famous purple dyes. We learn, from Pliny, that different plants, and likewise the ashes of plants, which no doubt contained alkali, were employed as detergents. He mentions particularly the _Struthium_ as much used for bleaching in Greece, a plant which has been identified by some with _Gypsophila Struthium_. But as it does not appear from John Sibthorp's _Flora Graeca_, edited by Sir James Smith, that this species is a native of Greece, Dr Sibthorp's conjecture that the _Struthium_ of the ancients was the _Saponaria officinalis_, a plant common in Greece, is certainly more probable.
In modern times, down to the middle of the 18th century, the Dutch possessed almost a monopoly of the bleaching trade although we find mention of bleach-works at Southwark near London as early as the middle of the 17th century. It was customary to send all the brown linen, then largely manufactured in Scotland, to Holland to be bleached. It was sent away in the month of March, and not returned till the end of October, being thus out of the hands of the merchant more than half a year.
The Dutch mode of bleaching, which was mostly conducted in the neighbourhood of Haarlem, was to steep the linen first in a waste lye, and then for about a week in a potash lye poured over it boiling hot.
The cloth being taken out of this lye and washed, was next put into wooden vessels containing b.u.t.termilk, in which it lay under a pressure for five or six days. After this it was spread upon the gra.s.s, and kept wet for several months, exposed to the suns.h.i.+ne of summer.
In 1728 James Adair from Belfast proposed to the Scottish Board of Manufactures to establish a bleachfield in Galloway; this proposal the board approved of, and in the same year resolved to devote 2000 as premiums for the establishment of bleachfields throughout the country.
In 1732 a method of bleaching with kelp, introduced by R. Holden, also from Ireland, was submitted to the board; and with their a.s.sistance Holden established a bleachfield for prosecuting his process at Pitkerro, near Dundee.
The bleaching process, as at that time performed, was very tedious, occupying a complete summer. It consisted in steeping the cloth in alkaline lyes for several days, was.h.i.+ng it clean, and spreading it upon the gra.s.s for some weeks. The steeping in alkaline lyes, called _bucking_, and the bleaching on the gra.s.s, called _crofting_, were repeated alternately for five or six times. The cloth was then steeped for some days in sour milk, washed clean and crofted. These processes were repeated, diminis.h.i.+ng every time the strength of the alkaline lye, till the linen had acquired the requisite whiteness.
For the first improvement in this tedious process, which was faithfully copied from the Dutch bleachfields, manufacturers were indebted to Dr Francis Home of Edinburgh, to whom the Board of Trustees paid 100 for his experiments in bleaching. He proposed to subst.i.tute water acidulated with sulphuric acid for the sour milk previously employed, a suggestion made in consequence of the new mode of preparing sulphuric acid, contrived some time before by Dr John Roebuck, which reduced the price of that acid to less than one-third of what it had formerly been. When this change was first adopted by the bleachers, there was the same outcry against its corrosive effects as arose when chlorine was subst.i.tuted for crofting. A great advantage was found to result from the use of sulphuric acid, which was that a souring with sulphuric acid required at the longest only twenty-four hours, and often not more than twelve; whereas, when sour milk was employed, six weeks, or even two months, were requisite, according to the state of the weather. In consequence of this improvement, the process of bleaching was shortened from eight months to four, which enabled the merchant to dispose of his goods so much the sooner, and consequently to trade with less capital.
No further modification of consequence was introduced in the art till the year 1787, when a most important change was initiated by the use of chlorine (q.v.), an element which had been discovered by C.W. Scheele in Sweden about thirteen years before. The discovery that this gas possesses the property of destroying vegetable colours, led Berthollet to suspect that it might be introduced with advantage into the art of bleaching, and that it would enable practical bleachers greatly to shorten their processes. In a paper on chlorine or oxygenated muriatic acid, read before the Academy of Sciences at Paris in April 1785, and published in the _Journal de Physique_ for May of the same year (vol.
xxvi. p. 325), he mentions that he had tried the effect of the gas in bleaching cloth, and found that it answered perfectly. This idea is still further developed in a paper on the same substance, published in the _Journal de Physique_ for 1786. In 1786 he exhibited the experiment to James Watt, who, immediately upon his return to England, commenced a practical examination of the subject, and was accordingly the person who first introduced the new method of bleaching into Great Britain. We find from Watt's own testimony that chlorine was practically employed in the bleachfield of his father-in-law, Mr Macgregor, in the neighbourhood of Glasgow, in March 1787. Shortly thereafter the method was introduced at Aberdeen by Messrs Gordon, Barron & Co., on information received from De Saussure through Professor Patrick Copland of Aberdeen. Thomas Henry of Manchester was the first to bleach with chlorine in the Lancas.h.i.+re district, and to his independent investigations several of the early improvements in the application of the material were due.
In these early experiments, the bleacher had to make his own chlorine and the goods were bleached either by exposing them in chambers to the action of the gas or by steeping them in its aqueous solution. If we consider the inconveniences which must have arisen in working with such a pungent substance as free chlorine, with its detrimental effect on the health of the work-people, it will be readily understood that the process did not at first meet with any great amount of success. The first important improvement was the introduction in 1792 of _eau de Javel_, which was prepared at the Javel works near Paris by absorbing chlorine in a solution of potash (1 part) in water (8 parts) until effervescence began. The greatest impetus to the bleaching industry was, however, given by the introduction in 1799 of chloride of lime, or bleaching-powder, by Charles Tennant of Glasgow, whereby the bleacher was supplied with a reagent in solid form which contained up to one-third of its weight of available chlorine. Latterly frequent attempts have been made to replace bleaching-powder by hypochlorite of soda, which is prepared by the bleacher as required, by the electrolytic decomposition of a solution of common salt in specially constructed cells, but up to the present this mode of procedure has met with only a limited success (see ALKALI MANUFACTURE).
_Bleaching of Cotton._
Cotton is bleached in the raw state, as yarn and in the piece. In the raw state, and as yarn, the only impurities present are those which are naturally contained in the fibres and which include cotton wax, fatty acids, pectic substances, colouring matters, alb.u.minoids and mineral matter, amounting in all to some 5% of the weight of the material. Both in the raw state and in the manufactured condition cotton also contains small black particles which adhere firmly to the material and are technically known as ”motes.” These consist of fragments of the cotton seed husk, which cannot be completely removed by mechanical means. The bleaching of cotton pieces is more complicated, since the bleacher is called upon to remove the sizing materials with which the manufacturer strengthens the warp before weaving (see below).
In principle, the bleaching of cotton is a comparatively simple process in which three main operations are involved, viz. (1) boiling with an alkali; (2) bleaching the organic colouring matters by means of a hypochlorite or some other oxidizing agent; (3) souring, i.e. treating with weak hydrochloric or sulphuric acid. For loose cotton and yarn these three operations are sufficient, but for piece goods a larger number of operations is usually necessary in order to obtain a satisfactory result.
_Loose Cotton._--The bleaching of loose or raw cotton previous to spinning is only carried out to a very limited extent, and consists essentially in first steeping the material in a warm solution of soda for some hours, after which it is washed and treated with a solution of bleaching powder or sodium hypochlorite. It is then again washed, soured with weak sulphuric or hydrochloric acid, and ultimately washed free from acid. Careful treatment is necessary in order to avoid any undue matting of the fibres, while any drastic treatment, such as heating with caustic soda and soap, as used for other cotton materials, cannot be employed, since the natural wax would thereby be removed, and this would detract from the spinning qualities of the fibre. In case the cotton is not intended to be spun, but is to serve for cotton wool or for the manufacture of gun cotton, more drastic treatment can be employed, and is, in fact, desirable. Thus, cotton waste is first extracted with petroleum spirit or some other suitable solvent, in order to remove any mineral oil or grease which may be present. It is then boiled with dilute caustic soda and resin soap, washed, bleached white with bleaching-powder, washed, soured and finally washed free from acid. In these operations, a certain amount of matting is unavoidable, and it is consequently necessary to open out the material after drying, in scutchers.
_Cotton Yarn._--Cotton yarn is bleached in the form of cops, hanks or warps. In principle the processes employed are the same in each case, but the machinery necessarily differs. Most yarn is bleached in the hank, and it will suffice to give an account of this process only. The sequence of operations is the same as in the bleaching of cotton waste, and these can be conducted for small lots in an ordinary rectangular wooden vat as used in dyeing, in which the yarn is suspended in the liquor from poles which rest with their ends on the two longer sides of the vat. For bleaching yarn in bulk, however, this mode of procedure would involve so much manual labour that the process would become too expensive. It is, therefore, mainly with the object of economy that machinery has been introduced, by means of which large quant.i.ties can be dealt with at a time.
The first operation, viz. that of boiling in alkali, is carried out in a ”kier,” a large, egg-ended, upright cylindrical vessel, constructed of boiler-plate and capable of treating from one to three tons of yarn at a time. In construction, the kiers used for yarn bleaching are similar in construction to those used for pieces (see below). The yarn to be bleached is evenly packed in the kier, and is then boiled by means of steam with the alkaline lye (3-4% of soda ash or 2% caustic soda on the weight of the cotton being usually employed) for periods varying from six to twelve hours. It is essential that a thorough circulation of the liquor should be maintained during the boiling, and this is effected either by means of a steam injector, or in other ways. As a rule low pressure kiers (working up to 10 lb. pressure) are employed for yarn bleaching, though some bleachers prefer to use high pressure kiers for the purpose.