-2 it; 



DYEING. 



Pomer's 



taken out, aired, and cooled ; after which it is washed 

 in the river, and dried. 



250. Such is the process for dyeing scarlet, as di - 

 bed by Berthollet He ad.!?, that die projtortion.-. of 

 cochineal, and of solution of tin, put ciiliiT into the 

 boiling or into the reddening, are nut fixed. Tin re :irc 

 dyers who, according to Hcllot's account, succeed 

 well by putting two-thirds of the comjtosition, and a 

 fourth ot the cochineal, into the lx>ilin:r, and the re- 

 maining third of t!u- composition, with the remaining 

 three-fourth)* of the cochineal, into the reddening. 1 Icl- 

 lot asserts also, that it dot-- no harm to use tartar in the 

 reddening, provided that not more ot' it than half the 

 weight of the cochineal be put in ; and it has appeared 

 to him even to render the colour more pennant-nt. 

 This is at present the practice of several dyer-. 



25 ! . Some dyers do not take the cloth out of the boil- 

 ing, only refreshing it to make the reddening in the 

 same bath, by pouring in an infusion of cochineal, 

 which they have made apart, and with which they have 

 mixed the proper quantity of camnositian, i. e. solution 

 of tin. In this way they save time and fuel, and ob- 

 tain a scarlet equally fine. 



25 '2. In dyeing scarlet, it is of advantage to use tin 

 boilers, because the acid employed attacks copper, and 

 the solution it forms w it li it may affect the beauty of 

 the colour But as these are difficult to make of any 

 considerable size, and are liable to melt if the work- 

 men forget to withdraw the fire before emptying them, 

 many dyers use copper boilers. It is necessary, how- 

 ever, to keep these very clean, not to allow, the acid li- 

 quor to remain in them, and to prevent the cloth dy- 

 ed in them from touching the copper, by means either 

 of a net or a wicker basket. 



253. Scheffer directs for the boiling an ounce and a half 

 of solution of tin, with an equal quantity of starch, and 

 as much tartar to every pound of cloth. He observes, 

 that the starch serves to render the colour more uni- 

 form ; and he directs, to throw into the water when it 

 boils, a drachm of cochineal, to stir it well, to boil the 

 wool an hour, and afterwards to wash it. The wool 

 is then to be boiled half an hour in the reddening bath, 

 with half an ounce of starch, three quarters of an ounce 

 of solution of tin, half an ounce of tartar, and seven 

 drachms of cochineal. It appears, that Scheffer em- 

 ploys a much smaller quantity of solution of tin than 

 Hellot: but Hellot's solution, the manner of preparing 

 which we described under Mordants (214.), contains 

 much more tin. 



254. I'o?rner describes three principal processes for 

 dyeing scarlet, according as the colour is to be more or 

 less deep, or more or less inclining to orange. He puts no 

 cochineal into the boiling, which he composesof one ounce 

 six drachms of tartar, and an equal weight of solution of 

 tin, added after the tartar is dissolved, for every pound of 

 cloth. After it has begun to lx>il, he introduces the cloth, 

 and boils it for two hours. For the reddening of the first 

 process, he uses two drachms of tartar, and an ounce 

 of cochineal, afterwards adding gradually two ounces of 

 solution of tin For the reddening of the second pro- 

 cess, he uses the same quantity of cochineal, and two 

 ounces of solution of tin without any tartar. For that 

 of the third, he directs two drachms of tartar, an oun< e 

 of solution of tin, and two ounces of common salt, 

 with the above quantity of cochineal. The scarlet of 

 the first process is of the deepest shade : t!v:t of the se- 

 cond is less full, but more lively ; that of the third is 

 still more bright and pale. 



255. Dr Bancroft states, that he has often given to 



cloth a scarlet colour at a single lint protracted boiling, 

 by mixing the whole quantity of tartar, and solution of "' ' 

 tin. and adding the cochiiu-..!. alter the cloth has boil- *" ~,'~" - ' 

 cil ten or tit'teen minutes ; for such, gays he, is the at- */.. '"'" 

 traction of wool for the colouring matter, ns well ns COM. 

 for the oxide of tin, that it will take up lx>th very free- 

 ly, and retain them permanently, when thus mixed. 

 He acknowledges, however, that in this way, the cloth 

 is liable to imbibe both the mordant and the colour, w ith 

 some incqualitie-, owing to differences in the quality of 

 the wool ; and that it is safest to employ a previous boil- 

 ing in the way commonly practised. He iiUo mentions 

 that he has often dyed very beautiful scarlets, by pre- 

 paring or boiling the cloth with the whole quantity of 

 solution of tin and tartar at once, (as is commonly 

 done with alum and tartar), and afterwards dyeing it 

 unrinsed, with the whole of the cochineal in clean wa- 

 ter only. In this way he found the colouring particles 

 so completely taken up by the cloth, that the liquor 

 became as clear us the purest water, and the colour was 

 generally very good. 



256. After "having directed his attention very particu- Scarlvt i!ii- 

 larly, and for a long period of time, to the dyeing of scar- coverni by 

 let, Dr Bancroft perceived that scarlet was in reality a HrHancroft 

 compound colour, consi-ting of' about three-fourtlis of a '" 

 most lively pure crimson or rose-colour, and about one- j^? 

 fourth of a pure bright yellow ; and, consequently, thai 

 when the natural crimson of the cochineal is made scar- 

 let by the means always hitherto employed for dyeing 

 that colour, there must be a change produced equivalent 

 to a conversion of one-fourth of the cochineal colour- 

 ing matter, from its natural crimson to the yellow co- 

 lour; and as a better yellow might be obtained from other 

 drugs where it naturally exists, and at a much chc.-.per 

 rate than it costs obtained in this way, he concluded 

 that the ordinary method of producing a scarlet Was 

 highly injudicious, because unnecessarily expensive. 



" Convinced of this important truth," says he, " and 

 at the same time believing too easily, on the authority 

 of Hellot, Macquer, and others, that the natural crim- 

 son of cochineal was rendered scarlet only by the ni- 

 tric acid employed to dissolve the tin used in dyeing 

 that colour, I began a series of experiments for pro- 

 ducing it, without any such waste of the cochineal co- 

 louring matter. I ; or this purpose, it seemed nee< 

 to discover a mordant or basis, capable of permanently 

 fixing, and strongly reflecting the pure vivid cochineal 

 crimson or rose colour, without making it incline to the 

 yellow. I concluded, and found by experiments, that 

 the necessary purity and vivacity of colour could not 

 be obtained from an aluminous basis, however dissolv- 

 ed, though it doubtless fixes the particles of cochineal 

 more durably than any other mordant ; and the like 

 defect was found to accompany the solution of all the 

 other earths, as well as of the metals, tin alone except- 

 ed ; and with this further disadvantage, that most of 

 them either degraded or altered the natural colour of 

 cochineal very considerably. It followed, tl. in-fore, 

 that a basis to suit my purpose must be sought for in 

 the pure white calx or oxide of tin, so dissolved or com- 

 bined, as to reflect the cochineal crimson unch.-ii 

 ai-d witi- the greatest pocsiblc lustre. To produce* 

 t''ii-cl'orc. it was only necet-sary to snperadd, 

 end intimately combine, with this crim.-on or rose co- 

 lour, H suitable portion of n lively golden yellow, ca- 

 pable of being properly fixed and reflected by the same 

 basis Such a yellow I had previously disco\ci. 

 tin- (|in-citioi) balk, and also in what is properly called 

 young fustic, (li/tm cotmui), though its> colour was less 



