tuention only nanae alum, a salt of cry rare occur rence; while no account is given of any work for its artificial preparation, except one Spam, noticed by Phm, which was intended to el) stalaze the sulphates of col Per or iron. But the pas a,;e already referred to, renders It extremely probable that the common sulphate ol altmune was included among the substances to which he gas e the appellation of alum•ri: though it is no less certain, that the sulphates of hem and copper were class ed along with it, as he expre ssly states that two of them produced a black colour, with galls, and the peels ol the pomegranate.
17. We hay e already stated, that before the time of PI ny, the 1,1-yptians practised a kind of calico-printing, milieu they borrow( d from Ilindostan ; and it may be presumed, that crystallized alum, which is even now oc easionally imported to this country from India, and has been used there in the processes of dyeing during many ceramics. would have been carried thence with other dyeing drugs to Egypt. Whether the Egyptians, after obtaining alum from India, discovered at sonic future perio the method of manufacturing it at home, or af terwards derived their supply of this article from the in habitants of sonic of the countries bordering on India, who might have acquired the knowledge of preparing it from the Ilindoos, would he very difficult to determine ; but it is certain that the Egyptian alum was long highly celebrated; and Pliny expressly mentions that it was held in higher estimation than y other. If the Romans actually employed alum in dyeing with the Wnes, they probawy learned the use of it from the Egyptians.
18. Besides the Tyrian purple, and the various shades of led from the kermes, the Romans were acquainted with several other colours. It was customary among them, from the earliest times, fur newly married women to wear a yellow veil, a colour which was confined en tit ely to matrons; and those •l.o were employed in the games of the circus were distributed into divisions, each of which was dressed in an appropriate colour. The co lours mentioned are color prassinus, green ; rufatus. orange ; venetus, grey, or perhaps a light blue ; and white. Some idea may be formed of the qualities of these colours, by enumerating the substances with which they were procured. It is difficult to give a complete account of them; hut the following seem to have been the most important : madder, woad, the roots of anchusa tinctoria, or alkanet; the genista tine toria, or dyer's broom ; gallnuts, pomegranate peels, alder bark, the rinds of walnuts, the bark of the wal nut tree, and the pods of the Egyptian acacia. No ac count, however, has been transmitted to us, either by Greek or Roman writers, respecting the methods in which these substances were employed, or of the mor dants that were used along with them to give fixity to the it colouring principles.
19. The ancients were ignorant of the use of soap, a aubstance which gives the moderns a decided superiority over them in prep:ail:1g the stuff for the t eception of the dye. In order to remove the grease from the wool, and wash linen, they. employed a plant called by Pliny radi rula, and by the GI eeks c.reveioi, supposed to be otn sa primula. or soap-wort. Pliny notices another plant which was used for the same purpose. Homer represents the Princess NaliSiCa and her attendants washing their linen dollies in the Ditches, by trampling on them with their feet.
20. Whatever knowledge of dyeing the ancients pos sessed, appears to have been lost about the fifth century, a period when almost all the arts were forgotten, and scarce any traces of civilization remained in the western empire. A faint knowledge of the arts was, indeed, re tained in Italy, and kept alive by occasional intercourse with the East, in consequence of the crusades; and also by the importation of various articles of luxury and re finement, which was made at that time by the Vene tians from the same quarter. This importation continu ally afforded new materials for industry, and new objects for imitation, and gradually led to the revival of the arts in Italy. The knowledge of the methods of dye ing., as practised by the Greeks and Romans, was in some measure restored by tee acquisition of chemical science, which now began to shed a feeble light over the objects of human industry, and attained a state of improvement probably not inferior to that in which it existed in ancient times.
21. From Italy, the knowledge of dyeing gradually spread itself through the other states of Europe. Ar chil is said to have been discovered at Florence about the year 13JO, by a merchant of that city, who hap pening to observe that urine imparted a very fine co lour to a certain species of moss, was induced to experiments upon it, and thus learned the preparation of archil. In the year 1429, a treatise on dyeing made its appearance at Venice, of which nr improved edition was afterwards published in 1510 This work, however, was still very imperfect ; and in order to render it more use ful and extensive, Giovati Ventura Rosati, overseer of the arsenal at Venice, resolved to travel through the different parts ot Italy., and the neighbouring countries, where dyeing was practised, to obtain an accurate ac quaintance with the various processes of the art, and reduce them under a systematic form. He accordingly carried his design into effect, and in 1548, published the result of his observations and enquiries under the as sumed name of Plictho. This work united the different processes then employed, and, in the opinion of Bischoff, ought to be regarded as an important step towards the perfection which the art of dyeing afterwards attained, though, according to !knot, it is but little entitled to attention. It is a curious fact, that it contains no ac count either of cochineal cr indigo. Berthollet explains this circumstance, by supposing that neither of these dyes was employed at that time in Italy. Whatever un certainty may exist with respect to the time when co chineal was first used as a dye, no doubt can he enter tained, that long before the period at which Rosetti pub lished his work, the properties of indigo were well known. Bischoff indeed conjectures, that the indicum of was not a dyeing drug, but a substance used as a paint, and very different from our indigo; and that the contract which was made in 1194, between the cities of Bologna and Fel rata, respecting certain duties to be levied at the former upon indigo, had a reference to the indicum of Pliny. Dr Bancroft, (Philosophy of Permanent Colours, vol. i. 242,) however, has shown the identity of these substances, from the exact coinci dence ol the properties of indicum, as described by Pli ny., 'vim those of the modern indigo; and he quotes a passage from Caneparius, which) proves that indigo was brought by merchants from India and Alexandria, and thence imported to Venice, when that city was the entre pot of Europe and the East. The statement of Canupa tins alto seems to correct a mistake committed by Bee thollet, who mentions that the first indigo employed in Europe was imported by the Dutch from the East In dies. The fact is, that long before the Dutch had any intercourse with that country, indigo had been imported in considerable quantity from Egypt and Syria to Italy, and employed in dyeing.* Bischoff also has established, by the most decisive evidence, that indigo was employed as a dye before the Dutch visited the East Indies. He informs us, that woad-dyers were recognized among the Germans as a distinct trade, so early as 1339, and that they were afterwards incorporated by charter with cer tain dyers from Italy and Flanders, under the name of Art, Woad, and Fine Dyers ; that this body, soon after its establishment, excited the jealousy of a more ancient corporation, the Black Dyers; and as indigo was em ployed by the former, the Black Dyers exerted them selves so successfully in decrying the use of it, that the Elector of Saxony, listening to their selfish suggestions, was prevailed upon to issue severe prohibitions against those who should employ it in dyeing. In the prohibi tory edicts which were passed against it, it is described as a corrosive colour, and fit food only for the devil. These acts were passed between the years 1521 and 1547, which was a considerable time before the first voy age undertaken by the Dutch to the East Indies. See INDIGO.