DYEING. 



249 



Ptocesucs of clean water, with a fortieth of its weight of quercitron 

 ^ D^-nig. ^ bark, and the same weight of murio-sulphate of tin; and 

 ^"""V ** this last, being compared with the other half, to which 

 no quercitron yellow had been applied, was found to 

 possess the most colour, as might have been expected. 

 A piece of the cloth which had been dyed scarlet by co- 

 chineal and quercitron bark, as in the first experiment, 

 being at the same time boiled in the same water with 

 ammonia, did not become crimson, like that dyed scar- 

 let without the bark." 



" In this way of compounding a scarlet from cochi- 

 neal and quercitron bark, the dyer will at all times be 

 able, with the utmost certainty, to produce every possi- 

 ble shade between the crimson and yellow colours, by 

 only increasing or diminishing the proportion of bark. It 

 has, indeed, been usual at times, when scarletsapproaching 

 nearly to the aurora colour were in fashion, to superadd 

 a fugitive yellow, either from turmeric, or from what is 

 called young fustic (rhus colinus) ; but this was only 

 when the cochineal colour had been previously yellow- 

 ed as much as possible by the use of tartar, as in the 

 common way of dyeing scarlet: and therefore that prac- 

 tice ought not to be confounded with my improvement, 

 which has for its object to preclude the loss of any part 

 of the cochineal rose or crimson, by its conversion to- 

 wards a yellow colour, which may be so much more 

 cheaply obtained from the quercitron bark." 



" By sufficient trials, I have satisfied myself that the 

 cochineal colours, dyed with the murio-sulphuric solu- 

 tion of tin, are in every resjx?ct at least as durable as 

 any which can be dyed with any other preparation of 

 that metal; and they even seem to withstand the action of 

 boiling soap suds somewhat longer, and therefore I can- 

 not avoid earnestly recommending its use for dyeing 

 rose and other cochineal colours, as well as for com- 

 pounding a scarlet with the quercitron bark." ( Phil, of 

 Perm. Colours, i. 4-85.) Such are the results of Dr 

 Bancroft's researches on this very important colour. 

 His experiments certainly deserve the attention of the 

 practical dyer ; and, indeed, we understand that a por- 

 tion of yellow colouring matter obtained from the quer- 

 citron bark, or rliut cotinus, is now very generally em- 

 ployed in this country with cochineal for dyeing scarlet. 

 The tartar is not, however, entirely abandoned, though 

 it is much more sparingly used than formerly. 

 Shades of 2fi5. As the reddening which has been used for dyeing 

 olour from scarlet is never entirely exhausted of its colouring matter, 

 but still contains a portion which varies in quantity ac- 

 cording to the fineness of the powder to which the co- 

 chineal was reduced, and the length of time it has been 

 boiled, it may still l>e employed to produce shades of a 

 sadder cast ; but the nature of the residuum being sel- 

 dom the same, it would be vain to point out the parti- 

 cular colours to be dyed with it, or the ingredients ne- 

 UiMiy to be added for brighter shades. Every thing, 

 in such case", must be left to the skill and experience of 

 the practical dyer. 



'2tiC>. Wool is dyed with kermes, by first boiling it 

 half an hour in water with bran ; then two hours in a 

 fresh bath, with one-fifth of Roman alum, and one-tenth 

 of tartar, to which sour water (49.) is commonly added; 

 after which it is taken out, tied up in a linen bag, and car- 

 ried to a cool place, where it i left some days. To ob- 

 tain a full colour, as much kermes as equals three- 

 fourths, or even the whole of the weight of the wool, is 

 put into a warm bath, and the wool is put in at the first 

 boiling. C loth being more dense than wool, either 

 spun or in the fleece, it requires one-fourth less of the 



VOL. VIII. PAHTJ. 



hauiU.il 

 baths. 



Red dye 



from 



lu.ni.i--. 



salts in the boiling, and of kermes in the bath. Be- 

 fore the wool which has just been dyed is taken to the 

 river, it may be dipped in a bath of water a little warm, 

 in which a small quantity of soap has been dissolved. 

 In this way the colour will acquire more brightness, 

 though it will be rendered a little of a rosy or crimson cast. 



267- Solution of tin has been tried with kermes as 

 well as with cochineal. Scheffer describes several pro- 

 cesses for dyeing in this way, but the colour always in- 

 clines to yellow or cinnamon, because the compound 

 formed of its colouring matter and the oxide of tin al- 

 ways retains a yellow hue. Berthollet ascribes this to 

 the action of the acid, but it is more probably owing, as 

 in the case of cochineal scarlet, to that of the tartar. 

 Dr Bancroft affirms, that with the same bases or mor- 

 dants, the colours from cochineal and from kermes 

 closely resembled each other. 



268. The red colour dyed upon wool with madder, 

 is greatly inferior in beauty to that obtained from co- 

 chineal or kermes ; but it has the advantage of being 

 cheaper and more durable. It is, therefore, often ap- 

 plied to coarser stuffs, which cannot admit of expensive 

 dyes. Before a woollen stuff is put into the madder 

 bath, it is first impregnated with a suitable mordant, by 

 boiling it for two or three hours with alum and tartar. 

 It is then left to drain, and after being slightly wrung 

 and put into a linen bag, it is carried to a cool place, 

 where it is allowed to remain for several days. 



26'9. The quantities of alum and tartar vary in dif- 

 ferent manufactories. Hellot recommends five ounces 

 of alum and one ounce of tartar to each pound of wool. 

 Poerner diminishes the proportion of tartar, and di- 

 rects that it should be only one-seventh of the alum ; 

 while Scheffer, on the contrary, says, that the quantity 

 of tartar should be double that of the alum. Berthollet 

 found that by employing one half tartar, the colour 

 sensibly bordered more on the cinnamon than when 

 the pro]x>rtion was only one-fourth. Dr Bancroft states 

 the proportions of the aluminous mordant to be, the 

 alum one- fourth or one-sixth, and the tartar one-twelfth 

 or one-sixteenth of the weight of the stuff. 



270. In preparing the madder, the bath must not be 

 allowed to boil, because that degree of heat would dis- 

 solve the fawn-coloured particles, which are less soluble 

 than the red, and thus debase the colour. After the 

 water has readied a temperature which the hand can 

 just bear, Hellot directs us to throw in half a pound of 

 the best grape madder for each pound of wool to be 

 dyed, and to stir it well before the wool is put in, which 

 must remain for an hour without boiling ; after which 

 it is recommended, in order that the colour may be 

 more effectually fixed, to boil it for four or five minutes 

 at the end of the operation. " Whether the colour be 

 in reality fixed more permanently by boiling the dyed 

 cloths a few minutes, as is commonly practised at the 

 conclusion of the operation, is a question (says Dr Ban-, 

 croft) which I am afraid to answer, as the results of se- 

 veral trials which I have made were not uniform ; but 

 if it should be found expedient to employ a boiling heat 

 for this purpose, all danger of any harm from it might 

 be avoided, by giving it with clean water, in a separate 

 pan, to which the cloths might be removed, after ha- 

 ving already imbibed sufficient colour, with only a 

 scalding heat ; in this way there would be no danger of 

 increasing the extraction of the yellowish-brown co- 

 louring matter, or promoting its application either to 

 the cloth, or the aluminous basis." See Phil, of Perm. 

 Col. ii. 227. 



Processes of 

 Dyeing. 



Effects of 

 solution of 

 tin. 



Madder 

 red. 



Proportion 

 of alum 

 and tar- 

 tar. 



Preparation- 

 of the dye- 

 ing bath. 



Tempera- 

 ture. 



