260 



DYEING. 



rtuone*- 



I :>-.- 

 ceo for gi- 

 ving a vivid 

 nii luting 

 cUow. 



Preparation 



* the bath. 



Various 

 ttudes of 



^ .Uuw. 



employed for each pound of cotton, to which a dr. 

 verdigrisc, mixed with a part of tlu- bath, is added. The 

 cotton i< dipped iunl wrought in this h.itli until it has 

 acquired nil uniform colour ; it is tlu-n taken out that .1 

 little Icy of soda may be added ; after which it is return- 

 ed into the bath, and ktpt there lor a full quarter of an 

 hour, when it is taken out, wrung, and dried. 



335. Lemon colour is dyed by the same process, 

 with this difference, that only one pound of weld is em- 

 ployed for each pound of cotton, ajid that the projxir- 

 tion of vcrdigrisc is diminished, or even entirely omit- 

 ted, and alum -uli-titute.l in its stead. The shades of 

 yellow may thus be varied in many dilferent ways. 



336. A more vivid and lasting yellow may be given 

 to cotton by the following cheap process, recommended 

 by 1 )r Bancroft. Take a sufficient quantity of the ace- 

 tite of aim nine, formed by dissolving after the rate of 

 one pound of sugar of lead and three pounds of alum, 

 anil the cotton or linen being properly cleansed, im- 

 inerse it in this mordant, (which ought to be about 

 blood-warm,) for the space of two hours ; let it then 

 be token out and moderately pressed or squeezed over 

 a proper vessel, to prevent the unnecessary waste of the 

 n Ionian t ; this being done, let it be well dried in a 

 stove heat, where it can be conveniently applied, and 

 then soaked again in the aluminous mordant ; it is then 

 taken out, and again pressed or squeezed as before, af- 

 ter which, without being rinsed, it is thoroughly wet- 

 ted in as much, and only as much, lime water as will 

 i. ii i veniently suffice for that purpose, and afterwards 

 dried. If a very full, bright, and durable yellow be 

 wanted, it may be proj>er to soak the stuff a third time 

 in the diluted aluminous mordant, and after drying, 

 wet it a second time with lime-water, and dry it again ; 

 hut in either ease, the cotton or linen, after its last im- 

 mersion, should be well rinsed in clear water, to sepa- 

 rate the uneombined particles of the mordant, whicli 

 .ire always injurious in the dyeing bath. The lime wa- 

 ter produces a more copious deposition of the alumine 

 upon the stuff, while, at the same time, it leaves a jx>r- 

 tion of calcareous matter united with the mordant, a 

 circumstance of considerable utility for the subsequent 

 raising of the colour. 



3'M. The bath is prepared by taking the quercitron 

 bark powdered, and inclosed in a linen bag, at the rate 

 of from twelve to eighteen pounds for every hundred 

 pounds weight of cloth, and putting it into the dyeing 

 vessel, containing a suitable quantity of cold water ; a 

 small fire is then lighted, and immediately after the 

 cotton or linen is introduced and turned for the space 

 of an hour or longer, during which the water should 

 gradually become wanner, but never warmer than the 

 hand am bear. At the end of the time mentioned, the 

 fire may be gradually increased until the liquor begins 

 to boil, after which the stuff may be allowed to remain 

 in it for a few minutes only, because longer boiling al- 

 ways renders the colour of a brownish cast. The linen 

 or cotton having thus acquired the proper shade of co- 

 lour, is taken out, rinsed, and dried a* HSU .1. 



338. " All the different shades of yellow," says Dr 

 Bancroft, " may in tlu's way be dyed from quercitron 

 bark. If it be used sparingly with a very moderate 

 heat, and the operation continued only for about half 

 an hour, a pale, though lively yellow, will result ; if 

 used more copiously, and the operation continued some- 

 what longer, a fuller colour will be produced ; and this 

 may be raised higher and higher, according us the heat 

 BO proportion of bark are increased, and the dyeing 

 pcratiun prolonged, so as indeed to produce a very 



dark brownish yellow, if the liquor b made to boil for fntatm 

 hall' mi hour." "See 1'liil. (>/ I'trin. Col. ii. I of Dy.ii.it. 



CHAP. IV. 

 Practises for Dyeing Jilue. 



339. The substances which are employed for dyeing 

 blue arc few in number. The only vegetable products 

 used for this purpose being indigo and woad ; Prus- 

 sian blue being scarcely ever employed as a dye. Ve- 

 getables yield by solution a carbon of a very fine blue; 

 and it seems probable, that when the blue c.'lour is ol>- 

 tained by fermentation, as is the case with indigo, the 

 carbonaceous matter is nearly set free, and remains 

 combined with an oil, which gives additional fixity to 

 the colour, and indicates the most suitable solvent. 



1. Processes for Dyeing ff 'ool Blue. 



340. Various methods are employed for dyeing blue Blue, 

 by means of indigo. To enter into a minute detail of 

 these would be foreign to the object of this Work ; and 



we must, therefore, restrict ourselves to a general \ Jew 

 -uch processes as appear to be best. '1 he bath for 

 dyeing blue is not prepared, as for other colours, in a 

 copper, but in a wooden vat, which is sunk into the 

 ground so as to be only breast high above it ; and as it is 

 of great consequence to preserve the heat of the bath, 

 the vat is placed in a situation where it is least apt to 

 cool. 



341. Blue may be dyed with pastel or woad, which ptel or 

 gives a permanent but not deep blue ; but if indigo be wood vau. 

 mixed with them, vats will be obtained very rich in 



colour ; and indeed these are almost the only ones used 

 for wool or woollen stuffs. They are called pastel or 

 woad vats, to distinguish them from those iu which 

 indigo alone is used. 



. I J . The celebrated woad vat, so generally employ- 

 ed for dyeing blue, is more complicated than any we 

 have hitherto mentioned. The operations which are 

 employed in different manufactories vary a good deal 

 from one another : we shall select the description of 

 one, which, in the opinion of Chaptal, is the most per- 

 fect of any with which, in the course of his extensive 

 experience, he was acquainted. 



J 13. Four hundred pounds of woad, well divided, Prcparotioi 

 are put into a vat seven feet in depth by five feet in "' " woatl 

 diameter. Thirty pounds of woad are then put into " 

 a caldron, to which, after three hours boiling, are add- 

 ed twenty pounds of madder and an equal quantity of 

 bran. The. ebullition is afterwards continued for h::lf 

 an hour, when the bath is recruited with twenty buc- 

 kets of water. The woad is then withdrawn, and the 

 bath allowed to become clear, after which it is returned 

 into the vat. The bath is then raked or stirred for 

 half an hour, after which the vat is covered, and at the 

 end of six hours again raked during another half hour. 

 This operation is repeated at the end of every tin 

 , hour-. When blue streaks make their appearance on 

 the surface of the liquor, eight or nine pomu! - of quick- 

 lime are mixed with it, which the workmen term gi- 

 boltom to the vat. They also introduce, at the 

 !-:iine time, indigo triturated with water, wlucli is used 

 in the proportion of from 10 Ibs. to .'> Ibs. according 

 to the shade of colour required. The raking is conti- 

 nued at the intervals prescribed, until the blue iioth, 

 already mentioned, be formed on the surface of the If- 

 quor, after which it begins to work. The vat is thai 



