362 BLEACHING 



BLASTING. Tho process of rending rocks by the uso of some explosive com- 

 pound, as gunpowder. See MINING. 



BLEACHING (Blanchement, Fr. ; Blcichcn, Ger.) is the process by -which the 

 textile filaments, cotton, flax, hemp, wool, silk, and the cloths made of them, as well 

 as various vegetable and animal substances, are deprived of their natural colour, and 

 rendered nearly or altogether white. The term bleaching comes from the French 

 verb blanchir, to whiten. 



The principal bleaching agents, besides alkalis, are chlorine, sulphurous acid, and 

 the combined action of air and light These are destroyers of colour. The chief 

 agents for removing colours which do not require to be previously decomposed, are 

 alkalis. The principal amount of the colouring-materials are removed from the cloth 

 by washing with alkalis : the last tint of whiteness is not removable by this means, 

 and it is to this last tint that the word bleaching has been more definitely applied. 



In ancient times bleaching, washing, and fulling were not distinctly separated ; 

 they were all practised. We read in the Scriptures of ' fine linen, white and clean,' 

 and in Greek authors, of 'raw linen,' of which towels were made, as well as of 

 ' shining fine linen,' for the same purpose, thus at once making the distinction. 1 

 The pure white was apparently not so common as with us. A pure surface was, 

 however, needful, in order to produce good colours, for which we are bound to give 

 the ancients credit, as wo know they were acquainted with them as pigments, and 

 are not, therefore, to be suspected of being unable to distinguish good from bad, 

 when transferred to textile fabrics. As their words for white and for colour are 

 plain enough in general, we must conclude that they had the power of obtaining 

 both fine whites and finely-dyed cloth; handkerchiefs were tied about the head 

 in various ways, as now in Lancashire, white and coloured. The Babylonians wore 

 white cloaks. 2 By their method of washing, the discovery of bleaching was inevitable, 

 the cloth being washed and dried several times in the sun. But it was not left in the 

 state of an accident only ; the word insolation shows that the effects of the sun had 

 been observed and classified, and this is stated to have been the chief method, as it is 

 now, of bleaching wax. Egypt and the East seem to have been the teachers in 

 bleaching. From Egypt were obtained alkalis, and soda mixed with lime. Both lime 

 and alkalis were used in the process. Potashes, or the ashes of plants, were also used, 

 and soap-plants, in all probability of various kinds, as it is not easy to decide on one. 

 The Saponaria officinalis, soap-wort, is still used, and the wake-robin or cuckowpint, 

 Arum maculatum ; the Gypsophila Struthium was considered by Linnaeus to be the 

 ancient one, and is still called Lanaria in Italy. Nor do we require to suppose that 

 this plant was first incinerated, as has been supposed, in the case of Borith, the fuller's 

 soap of the Bible. Vegetable decoctions are still used in China to bleach silk, and in 

 France also ; some have been patented even in England, although but little used. 

 The Latin method of obtaining white cloth is very well preserved, and as they got their 

 caustic soda from Egypt, it is probable that they got also their process thence ; nor is 

 it at all likely that Nicias of Megara invented fulling, as it was evidently well known 

 before the existence of any well-founded Greek tradition. Pictures exist in Pompeii 

 of men dancing the fuller's dance, or stamping cloth with their feet, as women now 

 practise in Scotland. Moderate-sized tubs were used : the clothes seem occasionally 

 to have been taken up by the hand, in order that they might be well turned. They 

 were then treated with ammoniacal liquors and soda. Urine was highly esteemed for 

 the purpose. The fullers obtained it by placing vessels at the corners of the streets, 

 which were removed when filled ; this practice acting at the same timo as a sanitary 

 precaution. The same method of carefully collecting this fluid, or ' old lant,' as it is 

 called, exists in the woollen districts of Lancashire and Yorkshire. A tax was laid 

 on it by Vespasian, so that the fullers might not receive it without payment. The 

 cloth was then sulphured, if it was intended to be white : this process was performed 

 under a conical frame like a small tent, the cloth being spread round the frame, and 

 a vessel of sulphur burned under it. 8 Potter's earth was then used according to cir- 

 cumstances. The fuller seems to have been a bleacher as well as domestic laundry- 

 man. He had, therefore, white as well as coloured dresses to deal with. For the 

 first he used Sardinian potter's earth, which could not be employed for prints or such 

 colours as easily changed (versicolores). For coloured cloth, sulphur was not used 

 by the potters, but fine Cimolian earth. The potter's earth seems to have been used 

 both before and after sulphuring, according to circumstances. This second process is 

 allied partly to our mode of chalking white dresses, still somewhat in use : but more 

 strongly allied to what is called dressing, stiffening, and finishing. Pliny says that 

 the Umbrian earth was only used for polishing vestments, also that it softened fine 

 colours and gave lustre to those that were faded in sulphuring. This shows that 



1 Philoxenus In Athenseus, ix. 77. Herod, i. 195. 



' Pompeii drawings ; see Smith's Dictionary, Lardncr's Cyclopaedia. 



