PRINTING ON CALICO. 



The acetate of alumine is prepared by a mixture of the 

 fulphate of alumine v\ith acetate of lead, both m a ftate of 

 folution ; fo that, on the theory of double decompofition, 

 fulphate of lead is formed, whieh precipitates, while the 

 acetate of alumine remains in folution. 



Since the demand for this article has been increafed on 

 account of the cxteafion of the printing trade. It has been pre- 

 pared from the pyroligneous acid by means of hme and alum. 

 The follow iiig is the method : 



The pyroligneous acid is hj-ft paficd through a ItiU, to 

 divert it of a portion of the tar which is always dilTolved in 

 it ; it is then faturated with lime or whiting ; and lallly, the 

 acetate of lime thus formed is decompofed by a heated folu- 

 tion of fulphate of alumine. The refult of this double 

 decompofition is fulphate of lime, which precipitates, and 

 acetate of alumine, which is drawn from the fediment of the 

 calcareous fulphate, and preferved for ufe. 



And here it may be neceflary to caution the manufac- 

 turer againll a misfortune that may befall him if he be 

 not converfant with the chemical nature of the fubftances he 

 employs. 



Magnefian lime-llone abounds in Derbyfhire, and in fome 

 of the adjacent counties ; and ftiould a maker of acetate of 

 alumine employ fuch lime in his procefs, the article which 

 it would produce would in all probabihty be entirely unfit 

 for the ufe of the calico-printer. But we mull be more 

 explicit. 



In employing the common lime in conjunftion with alum, 

 a. fulphate of lime will be formed, as mentioned above, and 

 this being nearly an infoluble fait, will precipitate. But here, 

 fulphate of magm lia would alfo be formed, which being a 

 folulk fait, would remain in folution, and increafe the fpe- 

 cific gravity of the liquor, a circumftance which would be very 

 apt to occafion the deception which we are anxious fhould 

 be avoided. If magnelian liine-ftonc be employed, the liquor 

 will appear good by the hydrometer ; but, as it will contain 

 more Epfom fait than acetate of alumine, it will be unfit 

 for every purpofe for which it was intended. 



While fpeaking of acetate of alumine, we cannot avoid 

 remarking that the procefs which has jr.ft been defcribed for 

 making this mordant, and which is followed invariably by 

 many of the manufacturers in the North, is extremely im- 

 proper, on account of the lime which is employed in it, be 

 the lime ever fo good, as that earth is very prejudicial to 

 every fpecies of red dye. The true way of making it, 

 though more expenlive, is that which was originally pointed 

 out by BerthiiUet, and which confills in decompofing ful- 

 phate of alumine i.y means of faccharum faturni, or acetate 

 of lead. 



In reverting to the remaining procelfes of the print-work, 

 it muft be noticed, that when the goods have paffed through 

 the weld or madder-copper, they are ufually carried to a 

 boiler containing wheat-bran and water, in which they are 

 winched for a confiderable time, for the purpofe of freeing 

 the white grounds from the (lain which they had acquired 

 from the madder or the weld. This procefs always impairs, 

 in fome meafure, ihe intenfity of the colours ; [branning has 

 alfo the effedl of giving a piak hue to all madder reds. But 

 it is not g.-neiiiHy known what a peculiar richnefs may be 

 imparted to maddjr-colours, by raifing them with a mixture 

 of bran and niadd;r ; that is, by mixing a portion of bran 

 with the madder in the Jird inftance. Mr. Parkes tells us 

 that he has fometimes produced colours in this way whofe 

 brilliancy has aftoailhed him. The operation of the bran in 

 producing this efFeCl will be explained hereafter ;] but it is a 

 neceffary operation, as there is no other mode fo convenient 

 for removing the ftain which is always given to the white 



part of a print by the madder, the bark, or the weld, wliich 

 has been ufed in dyeing it. 



It frequently is the cafe, however, that goods will not 

 bear to be fufficiently branned to clear the whites entirely 

 by that one operation ; [the temperature at which the opera- 

 tion of branning is performed, is very important. If bark 

 vellows are dyed at I00°, it iscuftomary to bran fuch goods 

 at 1 1 5° or 1 20'', as it is a principle always to bran at a 

 higher temperature than the goods are dyed at. Madder- 

 work mull be branned at a boiling heat ;J fuch goods, 

 therefore, are partially cleanfed in the branning-copper, and 

 are then laid on the grafs for fome days, till they become 

 perfectly clean. 



But within a few years a new method has been intro- 

 duced, which confifts in immerfing the pieces for a certain 

 time in a very weak folution of one of the bleaching falts, 

 fuch as oxymuriate of potafli, foda, or magnefia. [A Scotch 

 houfe of great confequence had praftifed this method a 

 confiderable time ; and in the year 181 2, a perfon vifited 

 Lancafliire for the purpofeof inftrutling the Englirti printer* 

 in the method.] This fimple procefs, which effetls in a 

 few minutes what would require more than as many days in 

 grafs-bleaching, is now much pradlifed, and promifes very 

 foon to fuperfede crofting entirely. This is a mod import- 

 ant improvement, as fome of the large printers formerly 

 required as much land to fpread out their goods upon, at 

 would make a farm of a very confiderable ilze. 



Befides the kinds of calico-printing already mentioned, 

 there are others which it will be proper to notice in thi» 

 place. Of thefe, what is called rejljl-iuork, is now done ia 

 confiderable quantities. It is conduced in the following 

 manner : 



A certain preparation of copper, mixed either with flour- 

 pafte, with gum, or with pipe-clay and gum, is printed 

 on the calico, in any fiiape or of any pattern that may be 

 defired. [The fulphate, the nitrate, the muriate, and the 

 acetate of copper, have all been employed for preparing the 

 refill -parte ; but the fulphate is the beft for the purpofe ; 

 unlefs a very concentrated folution of the four falts were pre- 

 pared by fucceffively diflblving each of them in pure water.] 

 When this is fufficiently dry, the goods are repeatedly dip- 

 ped in the blue vat till they have acquired that depth of tint 

 which may be required ; and then, when they are waflied, 

 and paffed tlirougli diluted fulphurlc acid, thofe parts which 

 had been printed with the preparation of copper, are found 

 to be a good white ; the preparation having effetlually 

 refirted the operation of the indigo, [the art of making an 

 indigo-vat confills in forming fuch a mixture of lime and 

 fulphate of iron as fhall moft effedlually deoxydize the 

 indigo ; as indigo has no afSnity for cloth in its natural or 

 oxygenized ftate. Hence, thofe parts of a piece which are 

 printed with a folution of copper will never be dyed blue in 

 one of tliefe vats ; becaufe the deoxydized indigo becomes 

 oxygenated the moment it touches the copper, which parts 

 with its oxygen to the indigo, and occalioiis it to become 

 iiiloluble, and confequently incapable of forming a dye. 

 Thus, while fulphate of iron has the power of deoxydizing 

 indigo, fulphate of copper, or any other fait of that metal, 

 is incapable of retaining its oxygen, whenever it comes in 

 contaft with that lingular fubftance in a rtate of deoxydize- 

 ment ; and it is a curious inftance of the different degrees of 

 intenfity by which oxygen is held by the different me- 

 tals;] though all the otlier parts of the clotli have received 

 a permanent dye. The various deep blue calicoes with 

 white fpots or white figures, which are now fo com- 

 mon, are generally done in this way ; and by a fimilar 

 management with fubfequent dyeing in madder, weld, or 



bark. 



