DYEING. 



Advantage 

 of this pro- 



I mportant 

 property of 

 thik scarlet 

 with respect 

 to candle 

 light. 



Additional 

 experiment* 

 with the 

 murio-tul- 

 phateof tin. 



U IH -rally computed at the rat* of one ounce for every 

 )Miund of cloth), and the colour produced will certain- 

 ly not prove inferior, in any respect, to that dyed with 

 much more ex]xMicc and trouble, in the ordinary way. 

 When a rose colour is wanted, it may be readily and 

 cheaply dyed in this way, only omitting the quercitron 

 bark, instead of the complex method now practised, of 

 tir>t producing a scarlet, and then changing it to arose, 

 by the volatile alkali contained in stale urine, set free 

 or decomposed by potash or by lime ; and even if any 

 one should still unwisely choose to continue the prac- 

 tice of dyeing scarlet without quercitron bark, he need 

 only employ the usual proportions of tartar and cochi- 

 neal, with a suitable quantity of the murio-sulphate of 

 tin, which, while it costs so much less, will be more 

 effectual than the dyers' spirit." 



461. " Several hundreds of experiments warrant my 

 assertion, that at least a fourth part of the cochineal 

 generally employed in dyeing scarlet, may be saved by 

 obtaining so much yellow as is necessary to compose this 

 colour from the quercitron bark ; and indeed nothing 

 can be more self-evident, than that such an effect, ce- 

 lerit parihut, ought necessarily to result from this com- 

 bination of different colouring matters, suited to pro- 

 duce the compound colour in question." 



262. " The scarlet composed of cochineal crimson, 

 and quercitron yellow, is moreover attended with this 

 advantage, that it may be dyed upon wool and woollen 

 yarn, without any danger of its being changed to a rose 

 or crimson, by the process of fulling, as always hap- 

 pens to scarlet dyed by the usual means. This last be- 

 ing, in fact, nothing but a crimson or rose colour, yel- 

 lowed by some specific or particular action of the acid 

 of tartar, is liable to be made crimson again by the 

 application of many chemical agents (which readily 

 overcome the changeable yellow produced by the tar- 

 tar), and particularly by calcareous earths, soap, alka- 

 line salts, &-c. But where the cochineal colouring mat- 

 ter is applied and fixed, merely as a crimson or rose co- 

 lour, and is rendered scarlet by superadding a very 

 permanent quercitron yellow, capable of resisting the 

 strongest acids and alkalies, (which it does when dyed 

 with solutions of tin), no such change can take place, 

 because the cochineal colour having never ceased to be 

 crimson, cannot be rendered more so, and therefore 

 cannot suffer by those impressions or applications which 

 frequently change or spot scarlets dyed according to the 

 present practice." 



263. " There is also a singular property attending 

 the compound scarlet dyed with cochineal and querci- 

 tron burk, which is, that if it be compared with ano- 

 ther piece of scarlet dyed in the usual way, and both 

 appear by day-light exactly of the same shade, the for- 

 mer, if they be afterwards compared by candle-light, 

 will appear to be at least several shades higher and ful- 

 ler than the latter ; a circumstance f some importance, 

 when it is considered how much this and other gay co- 

 lours are generally worn and exhibited by candle light 

 during a considerable part of the year." 



264. " To illustrate more clearly," continues Dr Ban- 

 croft, " the effects of the murio-sulphuric solution of 

 tin with cochineal in dyeing, I shall state a very few of 

 my numerous experiments therewith ; observing, how- 

 ever, that they were all several times repeated, and al- 

 ways with similar effects: 



" 1st, I boiled one hundred parts of woollen cloth in 

 water, with eight parts of the murio-sulphuric solution 

 of tin, during the space of ten or fifteen minutes ; I 

 then added to the same water four parts of cochineal, 



and two parts and a half of quercitron bark in powder, ft 

 and boiled the cloth fifteen or twenty minutes longer ; of 

 at the end nf which it had nearly imbibed all the co- v "" 

 lour of the dyeing liquor, and received a very good, 

 even, and bright scarlet. Similar cloth dyed of that 

 colour at the same time in the usual way, and with a 

 fourth part more of cochineal, was found upon compa- 

 rison to have somewhat less body than the former ; the 

 effect of the quercitron bark in the first case having 

 been more than equal to the additional portion of co- 

 chineal employed in the latter, and made yellow by the 

 action of tartar. 



" 2d, To see whether the tartrite of tin would, be. 

 sides yellowing the cochineal crimson, contribute to 

 raise and exalt its colour more than the murio-sulphate 

 of that metal, I boiled a hundred parts of cloth with 

 eight parts of the murio-sulphuric solution, and six 

 parts of tartar, for the space of one hour : I then dyed 

 the cloth unrinsed, in clean water, with four parts of 

 cochineal, and two parts and a half of quercitron bark, 

 which produced a bright aurora colour, because a dou- 

 ble portion of yellow had been here produced, first by 

 the quercitron bark, and then by the action of tartar 

 upon the cochineal colouring matter. To bring back 

 this aurora to the scarlet colour, by taking away or 

 changing the yellow produced by the tartar, I divided 

 the cloth whilst unrinsed into three equal parts, and 

 boiled one of them a few minutes in water, slightly 

 impregnated with potash; another in water with a little 

 ammonia ; and the third in water containing a very 

 little powdered chalk, by which all the pieces became 

 scarlet ; but the two last appeared brighter than the 

 first, the ammonia and the chalk having each rosed the 

 cochineal colour rather more advantageously than the 

 potash. The best of these, however, by comparison, 

 did not seem preferable to the compound scarlet dyed 

 without tartar, as in the preceding experiment ; conse- 

 quently, this did not seem to exalt the cochineal colour 

 more than the murio-sulphate of tin ; had it done so, the 

 use of it in this way would have been easy, without 

 relinquishing the advantages of the quercitron yellow. 



" 3d, I boiled one hundred parts of woollen cleth 

 with eight parts of the murio-sulphuric solution of tin 

 for about ten minutes, and then added four parts of co- 

 chineal in powder, which by ten or fifteen minutes more 

 of boiling, produced a fine crimson. This I divided in- 

 to two equal parts, one of which I yellowed, or made 

 scarlet, by boiling it for fifteen minutes with a tenth of 

 its weight of tartar, in clear water ; and the other, by 

 boiling it with a fortieth of its weight of quercitron 

 bark, and the same weight of murio-sulphuric solution 

 of tin ; so that in this last case, there was an addition 

 of yellow colouring matter from the bark, whilst in the 

 former, no such addition took place, the yellow neces- 

 sary for producing the scarlet having been wholly gain- 

 ed by a change and diminution of the cochineal crim- 

 son or rose-colour ; and the two pieces being' com- 

 pared with each other, that which had been rendered 

 scarlet by an addition of quercitron yellow was, as 

 might have been expected, several shades fuller than 

 the other. 



" 4th, I dyed one hundred parts of woollen cloth 

 scarlet, by boiling it first in water, with eight parts of 

 murio-sulphate of tin, and twelve parts of tartar, for 

 ten minutes, and then adding five parts of cochineal, 

 and continuing the boiling Cor fifteen minutes. This 

 scarlet cloth I divided equally, and made one part crim- 

 son, by boiling it with a little ammonia in clean water ; 

 after which I again rendered it scarlet by boiling it in 



