The Dyer's Guide. Chapter I. Introductory. On the theory of fast and fugitive colours.

The Dyer's Guide
Being a Compendium of the Art of Dyeing
Linen, Cotton, Silk, Wool, Muslin, Dresses, Furniture, &c. &c.

With The Method of
Scouring Wool, Bleaching Cotton, &c.
Directions for Ungumming Silk, And For Whitening And Sulphuring Silk And Wool.
And Also
An Inttroductory Epitome of The Leading Facts in Chemistry, As Connected With The Art of Dyeing.

By Thomas Packer,
Dyer and Practical Chemist.

"Cet arte est un des plus utiles et des plus merveilleux qu'on connoisse."
- Chaptal.

"There is no art which depends so much on chemistry as dyeing."
- Garnett.

Second Edition,
Corrected and Materially Improved.

Printed for Sherwood, Gilbert, And Piper,

Ma,ny attempts have been made by chemical philosophers to account for the permanence or want of permanence of various colours, when imparted to cloths and other bodies as a dye. Among these, Hellot, D'Apligny, and others of the old, and Berthollet, Bancroft, Henry, and others of the modern school, maybe mentioned.

The power of resisting vegetable acids, alkalies, and soap, and, above all, the action of air and light, constitutes the durability of a colour. But this property has a very unequal standard, according to the nature of the colour and the species of the stuff.

There is no obscurity in the action of water, alkalies, acids, and soap: for a solution is effected by means of these agents, or a small portion of acid or alkali unites to the combination, which forms the colour. But this is not the case with the action of light and air. Till lately, however, it was not known in what this action consisted.

Of the two principles which compose atmospheric air, it is only the oxygen gas which acts on the colouring particles. It combines with them, and thus impairs their colour or makes them fade. But its action is soon chiefly exerted on the hydrogen which enters into their composition, and it thereby forms water. This effect may be compared to a feeble combustion. Hence the carbon, which enters into the composition of the colouring particles, becomes predominant, and the colour usually passes to yellow, dun, or brown, or other appearances.

Light promotes this decomposition of the colouring particles, which frequently takes place only with its concurrence, and thus it contributes to the destruction of the colour. Heat also favours the same result, but less efficaciously so, unless it have a certain intensity.

* Berthollet. It is concluded, therefore, that colours are more or less fixed in the air, according to the greater or less tendency which the colouring particles have to undergo this change*. Hence the utility of mordants in rendering fugitive colours fast.

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