DYEING. 



263 



V more 

 iuiple pro 



IMS. 



green. 



green from 

 quercitron. 



Precedes solution my be added, which ought to be mixed with 

 at' Dyeing. g|- ea t care . After having gently boiled the cloth in it 

 ""Y"' for seven or eight minutes, it is taken ottt and cooled j 

 the bath is emptied to about three-fourths, perhaps 

 somewhat more or less, according to the shade of green 

 to be produced ; it is then filled with a decoction of fus- 

 tic, and when this bath is very hot, the cloth which had 

 been dyed blue, and cooled, is dipped into it, until it 

 has acquired the proper shade. 



378. The following process, which is more simple, is 

 described by Berthollet. A boiling is first given as for 

 welding ; and the cloth, being afterwards washed, fus- 

 tic in chips inclosed in a bag is put into the same bath, 

 and boiled for an hour and a half; it is then taken out, 

 and the bath cooled to a temperature which the hand can 

 support. Nearly a pound and a quarter of the solution 

 of indigo, for each piece of cloth of eighteen ells to be 

 dyed, is then added ; at first it is to be turned rapidly, 

 and afterwards slowly ; the cloth is to be taken out be- 

 fore the bath boils. It is proper to put in only two-thirds 

 of the solution at first, to take out the cloth after two or 

 three turns, and then to add the last third ; the colour 

 is thus rendered more uniform. If it is observed, that 

 the colour does not take well, a little calcined alum re- 



Saion apple duced to powder is added. The Saxon apple-green is 

 dyed in the bath which has served for Saxon green, af- 

 ter one-third or one-half of it has been taken out, and 

 after it has been cooled. The cloth is turned in it un- 

 til it is near boiling. 



379. Woollen stuffs, whichhave previously been dyed 

 blue in the common indigo vat, may also receive any of 

 the various shades of green, which are usually communi- 

 cated in this way from weld, by lx>iling them in water 

 with about one-eighth part of their weight of alum, and 

 afterwards dyeing them unrinsed with about the same 

 proportion of quercitron bark, and a little chalk added 

 towards die end of the process. A beautiful Saxon 

 green may be obtained from quercitron, by the fcllow- 

 in.if process, recommended by Dr Bancroft. The cloth 

 having previously received the Saxon blue, should af- 

 terwards be well rinsed, to separate, as far as water will 

 do it, the acid imbibed in combination with the indigo, 

 and which has a strong tendency to throw down ;ind 

 weaken the quercitron, as well as the weld yellows. 

 To counteract more effectually the operation of the acid, 

 it will be proper to add about three pounds of chalk, 

 with ten or twelve pounds ot'al'iin, for the preparation 

 liquor of a hundred pounds weight of clot)), which is to 

 \te turned and boiled, as usual, for about an hour ; and 

 then, without changing the liquor, t<-n or twelve pounds 

 of bark, powdered and tied up in a bag, may be put 

 into it, and die dyeing continued, taking care frequent- 

 ly to agitate the bag, in order that the colour of the 

 bark may spread equally through die liquor. It will 

 be found, however, that the yellow will manifest itself 

 but slowly in this way, by reason of the sulphuric acid 

 imbibed with die blue colour, joined to that of the 

 alum in the preparation liquor, which die portion of 

 chalk before mentioned will not have been sufficient 



Tcome ; and dierefore when the dyeing with bark 

 has continued about 15 minutes, it will l>e proper to 

 lother pound of clean powdered chalk, stirring it 

 well through die liquor, and to repeat this addition af- 

 tcr ard.t, once, twice, and even three times, at inter- 

 vals of six or eight minutes, if the colour does not rise 

 sufficiently without it. By these additions, says Dr 

 Bancroft, die quercitron yellow will manifest and ap- 

 ply itself abundantly and equally, so as to produce very 

 VOL. viii. PART i. 



beautifully greens, which, by varying the proportions 

 of indigo, as well as of bark and alum, may be varied 

 at pleasure. The chalk in this case does not merely 

 answer the purpose of separating the acid left in the 

 cloth, by the sulphate of indigo and the alum ; but by 

 uniting with this acid, it becomes a sulphate of lime, 

 and fixes itself, in part at least, us a basis in die fibre* 

 of the cloth, where it helps to raise the colour, and 

 also to render it a little more durable. At present the 

 Saxon greens are commonly dyed with the old fustic, 

 because the colour of this wood is not thrown down by 

 acids, so much as that of the bark and weld : and this 

 difference enables the dyer, when he has extracted the 

 fustic colour by previous boiling, to mix the sulphate 

 of indigo with it, and dye die cloth green by one 

 operation, after it has been prepared as usual with 

 alum and tartar. The process, however, which Dr 

 Bancroft has described for doing this with bark, i.s 

 fully as cheap and expeditious, and the green produced 

 will be more beautiful, because the quercitron yellow 

 is much more bright and clear than that of fustic. 

 See Phil, of Perm. Col. vol. ii. p. 135. 



380. Dr Bancroft has described anotner process, by 

 which beautiful Saxon greens may be produced, cheap- 

 ly and expeditiously, by combining the yellow of quer- 

 citron, the murio-sulph.ite of tin and alum, with the 

 sulphate of indigo. " To produce this combination 

 most advantageously, (says he,) the dyer, for a full 

 bodied green, should put into the dyeing vessel aftev 

 the rate of six or eight pounds of powdered b;irk, (in a 

 bag) for every hundred pounds weight of cloth, with 

 only a small proportion of water, as soon as it begins to 

 grow warm ; and when it begins to boil, he should add 

 about six pounds of murio-sulphate of tin, (with the 

 usual precautions,) and a few minutes after about four 

 pounds of alum ; these having boiled together five or 

 six minutes, cold water should be added, and the fire 

 diminished so as to bring the heat of the liquor nearly 

 down to what the hand is able to bear ; and immediate- 

 ly after this, as much sulphate of indigo is to be added 

 as will suffice to produce the shade of green intended 

 to be dyed, taking care to mix it thoroughly widi the 

 dyeing liquor by stirring, &c.; and this being done, the 

 cloth, previously scoured and moistened, should be ex- 

 peditiously put into the liquor, and turned very briskly 

 through it for a quarter of an hour, in order that the 

 colour may apply itself equally to every part, which it 

 will certainly do in this way with proper care. By 

 these means, very full, even, and beautiful greens, may 

 generally be dyed in half an hour; and during this 

 space, it is best to keep the liquor at rather less than a 

 boiling heat. Murio-sulphate of tin is infinitely pre- 

 ferable, for this use, to the dyers' spirit ; because the 

 latter consists chiefly of nitric acid, which, by its high- 

 ly injurious action upon indigo, would render that 

 part of the green colour very fugitive, as I have found 

 by repeated trials. But no such effect can result from 

 the murio-sulphate of tin, since the muriatic acid ha 

 no action upon indigo, and the sulphuric is that very 

 acid which alone is proper to dissolve it for this use. 

 Respecting the beauty of the colour thus produced, 

 those who are acquainted with the unequalled lustre 

 and brightness of die quercitron yellows dyed with the 

 tin basis, must necessarily conclude, that the greens 

 composed therewith, will prove infinitely superior to 

 any which can result from the dull muddy yellow o( 

 old fustic: and in point of cxpence, it is certain th; 4 t 

 the bark, murio-sulphate of tin, and alum, necessary 

 1 L 



Procet-stl 

 pf Dyeing. 



Advantage i 

 of this pro 

 cess. 



Another 

 process stiU 

 more iu'.- 

 vantagepr-r. 



