31. Any improvements in dyeing, which have been made in B.ritain, must be ascribed entirely to the cxer ti ns -t p• nt. individuat•, mian".ed I y tic patronage of rr t. In rhino: the case was different; the i•ulure of that country, as we have already stated, t appointed wilier persons to superintend ta tty the praent c of chi.; in all its departments, but tell out suitable rewards for the encouragement of such luals as mold contribute by their discoveries to t•e pto;ress of tl c nrt. The benelieial effects of this liberal and Loh:Meucci policy were quickly felt in the numerous improv emcnts uc dyeing, which acre suggest ed from time t 'time by the eminent men who filled these official situations, and it is certainly matter of regret, that no appointment of the same kind has ever been pro posed in our own country, where so much importance is attached to nits and manufactures. We are supported by the authority of Mr Anderson' and Alr Ilome,t in maintaining that the superior brilliancy of colour, which astin :inshes seat rat articles of French manufacture above those of other nations, is greatly owing to this foster ing care of government.
:32. But though the British government has hitherto neglected to encourage an art, upon the proper cultiva tion of which so much of the success of our commercial competition with other nations must depend, a few of our countrymen have devoted their attention to dyeing, and furnished, at their own expence, the most valuable information to the public. Mr Henry of Manchester directed his attention to the subject at a very early pe riod, and published an interesting paper, (which is in serted in the 3(1v °tunic of the Memoirs of the Alanches ter Society.) "on the nature of wool, silk, and cotton, as objs:cts of the art of dyeing; on the various prepara tions and mordants requisite for these different substan ces; and on the nature and properties of colouring mat ter," &c. This paper is drawn up with the author's usual philosophical precision, and contains many inge nious views, and much useful information. His obser vations respecting the cause of the durability of Adria nople red, display an intimate acquaintance with the subject, and do great credit to his talents and informa tion. We arc indebted to Mr Henry for the first account of the nature of the aluminous mordant. lie sheaved, that win n the acetate of it ad was presented to the sul phate of alumine, a double decomposition took place ; that the acetic acid quitted the lead, and combined with the alumine, while the sulphuric acid united with the lead, thus forming two new salts, the acetate of aluminc, and the sulphate of lead.
30. No original treatise on dyeing, however, appear 1 in our language, till Dr Bancroft published his ex cellr at work, entitled, " Experimental Researches con cerning the Philosophy of Permanent Colours." The first vohnne of this work appeared in 1794; and the second, NVilkil had been long expected with much „nxiety, so lately as 1813. The author has furnished be world with the results of an immense number of ex periments, prosecuted with unremitting care during a long course of years, and at a great expense. Though ce has been preceded by authors of such distinguished ability, as Mr Henry and Mr Berthollet, the new facts and observations which he offers to his readers skew, to use his own words, that he did not find the subject ex hausted. His views arc often entirely original ; and lie has detected a considerable number of mistakes into ich Berthollet and others had fallen. He has investi gated with much ability the action of tartar in the dyeing of scarlet, and proved by the most decisive ex pet intents, that, with cochineal, the salts of tin produce only a crimson, contrary to the statements of that able chemist, ho had entirely misrepresented the operation of these substances in the production of the former of these co lours. Ile has ascertained, that scat let is a compound colour, formed by the superinduction of a crimson upon yellow ; and, in consequence of this discovery, he has proposed a method of dyeing this colour more cheaply, more expeditiously, and more durably, than by the ordi nary process. But the most important sect ice which
Dr Bancroft has rendered to the art of dyeing was, the introduction of quercitron as a yellow colouring matter, the use and application of which for dyeing, calico-print ing, &c. were exclusively vested in him for a term of years, by an act of parliament passed in the 25th year or his present Majesty's reign. After the term of the act expired, an unsuccessful attempt was made to obtain a renewal of it, on the grounds that the Doctor had exer cised his right more beneficially and liberally For the public, than providently towards himself and family; and that he had also been deprived of a great part of his just profits by various infringements of the act. A bill for that purpose was accordingly passed in the House: of Commons, in the 39th of his present Majesty; but it was lost in the House of Lords, in consequence of the strong opposition which it encountered from a great number of persons in the northern part of the kingdom, smite of whom had grown rich by the discovery. It doe., not appear that the public derived much advantage lion., this alienation of the Doctor's right, as the bark in ques tion soon rose to three times the price at which he had invariably supplied it, and would have been bound to supply it, for another term of seven years, if the bill had passed in his favour. The policy of sanctioning a monopoly expressly by law may be justly questioned ; but every candid and liberal mind will readily admit, that, considering the very important improvements in dyeing which Dr Bancroft has introduced, the long and severe labour to which he has submitted, and the gm eat expense which he has incurred in the prosecution of his inquiries, he is entitled to some higher remuneration for his services, than the country has yet thought proper to bestow.
34. " Of all the arts," says Berthollet, " that of dye ing, perhaps, with respect to its theory, requires the most extensive knowledge of natural philosophy ; be cause it is that which presents the greatest number of phenomena to analyze, of uncertain changes to ascer tain, and of relations to establish with air, light, heat, and many other agents, of which our knowledge hither to has been very imperfect." But these remarks, though certainly well-founded, ought not to discourage. If many facts remain still to be explained, science has al ready done much in determining the essential circum stances of particular processes, and excluding such as are either absurd or superfluous; in analyzing the sub stances employed by the dyer, and discovering the cau ses to which their action is to be ascribed; and lastly, in suggesting the means most likely to improve the art.
35. In the following account which we propose to give of the operations of dyeing, our object is not so much to bring forward a new treatise, as to collect and condense every thing useful that has already been written on the subject ; and to present a view of the art, which shall include the most recent improvements, without neglecting the description of those processes which have long received the sanction of experience. In the execution of this plan, we shall freely avail Ourselves of the labours of the most approved writers on dyeing, par ticularly of Berthollet and Bancroft, as well as of the different individuals who may have suggested improve ments in particular processes. In short, we shall aim at usefulness rather than novelty, and never introduce theo retical views, unless they have an obvious tendency to simplify or improve practical operations When facts occur which we cannot explain, we must be satisfied with detailing the process of the art, and wait for further light from experience, before we attempt to reduce them to theory.