been accurately measured, they would have agreed fufficiently well with this theory. It is not however confidered as free from objections, but by future observations muft its truth or fallacy be afcertained: fhould it be found to agree with fuch obfervations, it may throw fome light on the doctrine of the ascent of vapours, a matter hitherto fo much difputed.

CONSIDERATIONS relative to the NATURE of WOOL, SILK, and COTTON, as OBJECTS of the ART of DYING; on the various PREPARATIONS, and MORDANTS, requifite for thefe different SUBSTANCES; and on the NATURE and PROPERTIES of COLOURING MATTER. Together with fome OBSERVATIONS on the THEORY of DYING in general, and particularly the TURKEY RED; by THOMAS HENRY, F.R.S. and of the Amer. Philof. Society, held at Philadelphia.

READ DECEMBER 20, 1786.

N the following Memoir, on a subject to

by English writers, my principal intention is to prefent, at one view, the preparatory and other proceffes

Z 4

proceffes for the dying of wool, filk, and cotton, and to endeavour to deduce a theory better fuited to account for the refults, than has hitherto been advanced. In the execution of this undertaking it will be neceffary to repeat feveral things from Hellot, Macquer, and d'Apligny, who have written feparate treatifes on the dying of these. materials; and I am to confefs great obligations to that very celebrated chemift M. Berthollet, whose researches are, every day, affording new and important information in the several departments of the hermetic art.

The art of dying, or of imparting to different materials, employed for the fabrication of garments and furniture, thofe beautiful colours which are afforded by many articles of the vegetable, animal, and mineral kingdoms, appears to have been of high antiquity*. As most of these materials are, of themselves, either of dark and difagreeable colours, or elfe devoid of all colour, it is probable, that, even in the very earliest ages, the love of ornament, which is natural to mankind, would induce them to ftain their veftments with various colouring ingredients, efpecially with vegetable juices. But the art of imparting permanent dyes to cloth, and affixing to its fibres fuch colouring materials, as could not eafily be washed out by water, or obliterated

* Delaval on Light and Colours.

or

or greatly changed by the action of air, or of certain faline fubftances, to which they are liable to be exposed, and which are neceffary to render them clean, when foiled ;-this was an art which required the knowledge of principles not within the reach of untutored men, and only to be obtained by gradual inveftigation, and in long process of time.

It has been proved by our ingenious affociate, Mr Delaval, that the Egyptians were poffeffed of the art of dying, and even of that of printing on cloths. In a paffage, which he has quoted from Pliny, that author relates that the Egyptians having befmeared, or drawn on white cloth, with various fubftances, which were in themselves colourless, but capable of abforbing colouring matter, threw them into a caldron of hot liquor, tinged with dying materials; and that, though the parts, thus drawn upon, were not diftinguishable, before the cloth was immerfed in the colouring liquor, and though this liquor contained only one colour, it was furprizing to see the cloth taken out, ftained with several different colours, according as the different parts of it had been impregnated with the various fubftances, capable of receiving and altering the nature of the pigment.

This is so plain a description of the art of what is now called callico printing, that though it is my intention to refer thofe gentlemen, who wish to be more intimately acquainted with the ancient

history

history of dying, to that written by Mr. Delaval, and prefixed to his ingenious treatife on light and colours, yet I could not refrain from relating it on this occafion.

Permit me alfo to mention another hiftorical fact from the ancient history of this art. The Phoenicians held a decided pre-eminence in the tinctorian art, for many ages: their purple and fcarlet cloths were fought after by every civilized nation, and the city of Tyre, enriched by its commerce, increased to an amazing extent. But her career was ftopped by the vanity and folly of the Eaftern emperors; under whofe dominion, this opulent city had unfortunately fallen.

Defirous of monopolifing the wearing of the beautiful cloths of Tyre, thefe misjudging tyrants iffued most severe edicts, prohibiting any one from appearing in the Tyrian blue, purple, or fcarlet, except themselves, and their great officers of state. The enacting and enforcing of fumptuary laws requires great judgment, and delicacy; and much caution should be used, left, in curbing exceffive luxury, the arts, which are fupported by its moderate indulgence, fhould be deftroyed. Such however was the fate of the Tyrian dyes. Under the impolitic restraint imposed on the confumption of the Phoenician cloths, the manufacturers and dyers were no longer able to carry on their trade, it grew lan

guid, fickened, and expired: and, with the trade, the art likewise perished.

This example of the interference of government, fo materially injuring, and even annihilating an useful art, and the commerce depending on it, though carried to an excefs, never likely to be imitated in these days, fhould make minifters cautious that they do not form laws which may difcourage or fetter our manufactures. For freedom is the very foul of trade; and, in proportion as the one is invaded, the other will certainly decline.

In this nation, the art of dying had made no confiderable progrefs till about the beginning of the last century*. Before that period, our cloths were fent to Holland, to be dreffed and dyed. Probably however this was practifed only in the cafe of particular colours; for it appears that the dyers of London received their charter of incorporation from Henry the fixth. My friend Mr. Charles Taylor has put into my hands a fmall tract, entitled, A profitable book declaring dyvers approved remedies, to take out spots and staines, in filkes, velvets, linen, and woollen clothes. With divers colours how to die velvets and filkes, linen and woollen fuftian and threade. Also to dress leather and to colour felles &c. &c. very neceffarie for all men, especially for those who bath or shall have any doings

• Chamber's Cyclopædia, article Dying.

therein: