BLEACHING is the art of whitening thread and cloth. It has been treated at considerable length in the Encyclopedia. Our business here is merely to supply the defects of that article. These are chiefly two ; namely, 1. A very incomplete historical detail of the improvements in bleaching, at least as far as this country is concerned ; and, 2. The omission of any description of the present mode of bleaching, as practised by the,most enlightened manufacturers of Great Britain.
I. The Ancients, especially in Egypt, where white linen was a common article of clothing, must at an early period have been acquainted with the method of bleaching that substance, but none of their writers have left us any details on the subject. We know, however, from Pliny, that different plants, and like wise the ashes of plants, which no doubt contained alkali, were employed as detergents. Pliny men tions particularly the struthium as much used for bleaching in Greece. This plant has been consider ed by some as the gypsophila struthium. But as it does not appear from Sibthorp's Flora Greca, pub lished by Sir James Smith, that this species is a na tive of Greece, Dr Sibthorp's conjecture that the struthium of the Ancients was the saponaria qfficina Lis, a plant common in Greece, is certainly more pro bable. Mr Parkes, in his Essay on Bleaching (Che mical Essay, Vol. IV. p. 7), says, that Theoplirastus states that lime was used by the ancients in bleach ing ; and that a ship, partly loaded with linen, and partly with lime for bleaching it, was destroyed by the accidental access of water to the lime. We en deavoured, with some pains, to verify this quotation; and, for this purpose, turned over all the writings of Theophrastus with which we are acquainted, without being able to find any thing bearing the least allu sion to it. We have doubts whether lime could be employed as a detergent of linen, without injuring the texture of the cloth ; and, on that account, it would have gratified us exceedingly to have found such a statement in- so respectable and correct a writer as Theophrastus.
About sixty or seventy years ago, the art of bleach. ing was scarcely known in Great Britain. It was customary to send all the brown linen 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 out of the hands of the merchant more than half a year. The principal Dutch bleaching-grounds were in the neighbourhood of Haerlem ; and the great success of their bleach ings was ascribed to the superior efficacy of their water, which, according to the fashionable theory, of the time, was sea-water filtered and rendered sweet, by passing through their sand-downs. Indeed, it was long aprejudice on the Continent, that no water was efficacious for bleaching but sea-water.
The Dutch mode of bleaching was to steep the • linen for about a week in a potash ley poured over it boiling hot. The cloth bein6 taken out of this ley, and washed, was next put into wooden vessels containing butter-milk, in which it lay under a pres sure for five or six days. After this it was spread upon the grails, and kept wet for several months, ex- • posed to the sunshine of summer.
tablished a bleaching manufhctory. On applying to the principal Scotch makers of linen, they readily furnished him with a quantity of goods ; but after keeping them a whole year, he failed in all his en deavours to bleach them, and the proprietors were obliged to send them to Holland to get the process completed. Next summer his efforts were not more successful ; the linen was considerably injured, and even rendered tender by his management, but it was not whitened. Nevertheless, this man by per severance became in a few years an excellent prac tical bleacher. He had the merit of introducing the art into Great Britain, and his descendants at this day figure among the higher ranks in the metropolis.