PRINTING ON CALICO. 



part of the biifinefs was formerly conducted in a very un- 

 cleanly and negligent way ; but of late years fonie printers 

 have inciu-red a confiderable expence in the conftruction of 

 their dunging machines, with cocks for hot and cold water 

 attached to them, and thermometers to regulate the tem- 

 perature. Thofe erefted by Mr. Wright, a very ingenious 

 calico-printer, at Serines, near Difley, are the moft com- 

 plete of any we have yet feen. 



The intention of the dung is to abforb and remove that 

 portion of the mordant which is not actually combined with 

 the cloth, and which otherwife might ftain the white or 

 imprinted parts. 



We lufpect th-' dung of the cow is ferviceable in another 

 way befides that of cleanfing, though the printer may not 

 be aware of the nature of its operation. To clean calicoes 

 by immerfion in a dung-velfel, may appear to be a ftrange 

 phrafe ; but as this is the technical language of the trade, 

 no other could be employed with propriety. It is acknow- 

 ledged that madder, cochineal, and fome other dyes, pro- 

 duce much better colours on woollen than on cotton cloths, 

 owing to the former being of animal, and the latter of 

 vegetable origin. We prefume, therefore, that the dung 

 imparts an animal matter to the fibres of the cotton, and 

 that this animal matter afts as an additional mordant, and 

 thus more powerfully attracts the colouring particles of the 

 dye, than the mordants alone v.'ould be capable of doing. 

 BerthoUet, who analyfed the dung of the cow, found in it 

 a fubftance partaking of the nature of bile. 



If a piece of calico, prepared with the acetate of alu- 

 mine, be divided into two parts, and the fuperfluous mor- 

 dant removed from one of them by cow-dung and water, 

 and from the other by water only, though both fluids were 

 at the fame temperature, it will be found, on paffing the 

 two portions through a decot\ion of weld or quercitron 

 bark, that the yellow will be much more intenfe and bright 

 in that which had been fubmitted to the aclicKi of the cow- 

 dung. This is a fatisfaftory and decifive experiment. 



The procefs of dunging is an operation that varies in time 

 from five to forty minutes, according to the liyle of work. 

 The pieces are then taken to the river or wheel, to be more 

 effectually wafned ; after this they are pafled through tepid 

 water, in order that the workman may be affured that every 

 impurity is removed. 



His next care is to provide a copper boiler of pure cold 

 water, in which a fuiEcient quantity of madder is put, and 

 a fire lighted underneath it. The calicoes, printed and 

 rinfed as above, are now put into this boiler, and from the 

 time they are immerfed, the workman never ceafes to turn 

 the winch, fo as to pafs every part of the goods repeatedly 

 through the liquor, till the whole acquires a boiling heat. 

 Indeed, this operation is fometimes continued for ten or 

 fifteen minutes after the bath of madder actually boils, 

 when the pieces are taken out and wafhed. 



Madder is one of the moft valuable drugs we have, for a 

 ■yariety of purpofes in dyeing and calico-printing ; as it is 

 the agent bv which the bell and moft permanent blacks are 

 produced ; alfo the fineft purples, and everj' (hade of red from 

 a pale pink to a crimfon. But perhaps it may not be generally 

 known that this article improves by age. If a quantity of 

 madder-roots be ground, and then packed tight in a calk, 

 fo as to exclude the air, and are kept thus for fix months, 

 they wiU then dye a much better colour, and go much fur- 

 ther than they otherwife would have done, had thefe roots 

 been ufed as foon as they were ground. 



This procefs, which is called maddering, has the effeft of 

 imparting all the requifite colours to the goods, by means 

 of one operation, wluch may be thus explained. While one 



mordant precipitates the colouring matter of the madder to 

 a red, another precipitates a diff"erent portion of it to a 

 purple, another precipitates it to a black colour, and fo of 

 every poffible (hade, from a lilac to a black, and from a 

 pmk to a deep red. 



If a portion of weld or bark be added to the madder, 

 every (hade from a brown to an orange may be produced •' 

 whereas, if weld or bark alone be employed, aU colours 

 between a dark olive and a bright lemon can be imparted to 

 the cloth. Thefe changes are all occafioned by the play of 

 chemical affinities, and are due to the improved ftate of 

 chemical knowledge. 



. Here it may be worth remarking, that whenever it is of 

 confequence to produce the fineft yellows or more delicate 

 lemon colour, it is neceflar)- to dry the pieces in the open 

 air, as the ftove would not fail to injure fucK colours ; for 

 ftove-drying has always a tendency to convert a yellow to an 

 orange. It is alfo neceflary to be equally careful in the 

 operation of dunging the mordants for thefe pale yellows ; 

 for, ftiould this be done at a higher temperature than 96° 

 or 100°, their beauty will certainly be impaired. There is 

 another advantage in this, -viz. by dunging at this low tem- 

 perature, the dyeing maybe completed even at 110° or 

 thereabouts, which will give a much hvelier colour than where 

 a higher temperature has been employed. 



The mordants generally ufed in calico-printing are acetate 

 of iron for browns, blacks, lilacs, &c. and acetate of alumina 

 for all the different ftiades of reds and yellows. 



Formerly the acetate of iron was made by digefting old 

 iron hoops in four beer, or in very weak vinegar ; but of late 

 years it has chiefly been made with the pyrolio-neous acid, 

 [if wood be fubmitted to an intenfe heat, when inclofed in an 

 iron veflel of any kind with a proper aperture to allow the 

 vapour to pafs, this vapour on being condenfed forms the 

 acid in queftion, and is now known to be a kind of impure 

 vinegar. The wood in this cafe is converted into charcoal, of 

 which a great deal is prepared by this procefs, particularly 

 for the formation of gunpowder,] the oleaginous impurities 

 of which tend, in fome cafes, to improve the mordant. 



Blacks are alfo produced by the nitrate of iron [nitrate 

 of iron was not applied to calico-printing till within the laft 

 fifty years. This difcovery formed an important era in the 

 trade, as it aflxjrded the manufafturer the means of varying 

 his ftyles of work in a multiplicity of ways and forms, which, 

 till then, were entirely unknown,] and gallic acid ; the 

 mixture is called chemical black. This nitrate of iron is 

 made by diflblving metallic iron in a pecuhar kind of aqua- 

 fortis. Common aqua-fortis will not anfwer for this piir- 

 pofe ; for, though it may diffolve the iron with rapidity, 

 part of the metal is apt very foon to precipitate ; which 

 not only weakens tlie colour, but leaves the remainder fo 

 acidulous, that there is always a danger of fuch a preparation 

 injuring the texture of the cloth. 



It is, however, neceffary to remark, that the black which 

 is formed by this folution of iron, is produced in a different 

 way from blacks in general ; for, when common iron* 

 liquor is ufed for this purpofe, it is firft printed on the calico : 

 and when it has been fufficiently oxydized by cxpofure to the 

 air, the goods are boiled in a decocT;ion of madder, which 

 renders fuch parts as had been printed with the acetate of 

 iron an intenfe black. But the black from nitrate of iron 

 and galls is apphed at once to the cloth, and is not afterward* 

 raifed by dyeing. 



The calico-printer by ufing a black ready formed is thua 

 enabled to mix it with other colours, in cafes where by dye- 

 ing alone it could not be produced, as in conjunftion with 

 yellows and ohves, raifed by weld or quercitron bark. 



The 



