DYEING. 



225 



Adjective to it, causes die liquor to assnme a red colour, inclining 

 Colouring to ye |i OWj ant i forms a sma ll quantity of a beautiful red 

 v^""^/ precipitate. Muriatic acid produces nearly the same ef- 

 fect, but no precipitate. A solution of tartar converts 

 the liquor into a yellowish red, and slowly produces a 

 small quantity of a pale red precipitate. The superna- 

 tant liquor retains a yellow tinge, which is changed into 

 purple by the addition of an alkali. The precipitate is 

 quickly dissolved by the alkali, and the solution becomes 

 purple. A solution of alum heightens the colour of the 

 infusion, renders it redder, and produces a crimson pre- 

 cipitate. A mixture of alum and tartar produces a bright 

 lively colour, inclining to a yellowish red. A solution 

 of muriate of soda, (common salt), renders the colour 

 somewhat deeper, but does not make the liquor turbid. 

 Muriate of ammonia gives a purple tinge, without any 

 precipitate. Sulphate of soda produces no change. The 

 acetate of lead forms a purple, inclining to violet. Ni- 

 trate of lead, a delicate lively colour, between red and 

 cinnamon, but inclining most to the former. The sul- 

 phate, nitrate, muriate, and acetate of iron, produce 

 a dark violet, and even a full black colour, when they 

 are used in sufficient quantity. The salts of copper nnd 

 mercury debase the colouring matter of cochineal. Ni- 

 trate of zinc gives a lively bright blue colour, approach- 

 ing to purple. Muriate of zinc, a colour like the last, 

 but more of a purplish tinge. The salts of bismuth pro- 

 duce indifferent colours ; and the same remark may be 

 applied to the salts of cobalt, nickel, tungsten, antimony, 

 and manganese. 



tsof 104. Of all the metallic salts which affect the colour 

 the falls of of cochineal, the most important is the oxide of tin. 

 tin. About the year 1630, it was discovered by the acciden- 



tal falling of a solution of the nitrate of tin into a de- 

 coction of cochineal, that the colour of the latter in- 

 stantly passed from purple to a vivid scarlet. Different 

 salts of tin produce different effects ; but we must re- 

 serve the particular consideration of their properties, un- 

 til we come to examine the nature of mordants. 

 Carmine. 1 5 - When alum is added to a decoction of cochineal, 



it combines with its colouring matter, and forms the 

 beautiful lake railed carmine. A certain proportion of an- 

 tour, a bark brought from the Levant, of a colour paler 

 than cinnamon, and in general, chouan, the seed of a 

 plant likewise brought from the Levant, arc added. Ber- 

 thollet supposes that these two substances furnish, with 

 alum, a yellow precipitate, which serves to brighten the 

 colour of the cochineal lake. Carmine vas formerly pre- 

 pared from kermes, from which it takes its name, and 

 the nature of which we shall now consider. 



Icrroes. 106. Kcrmcs (coccus ilicisj, is an insect found in se- 



veral parts of Asia, and the soutli of Europe. It ap- 

 pears to have been employed at a very early period as a 

 dye, and was known to the ancients by the name of 

 coccus Laptriciis, cocctit injectoriiif, graniim tinclarium. 

 The term kerrnes is supposed to be of Arabic origin, and 

 signifies a little worm. The Italians afterwards formed 

 from it the words chcrmisi, cremcsino, and chermesiiio ; 

 and the French those of carmesen, carmine, and cra- 

 moiti. The English words carmine, and crimson, are of 

 the same origin. At a later period, kermes was also 

 ealled coccum scarlalinum, though the time at which it 

 first received this appellation cannot now be accurately 

 ascertained. The term granum was applied to it on ac- 

 count of its resemblance to a grain or berry ; and hence 



^OL. VIII. 



Adjective 

 Colouring 



Matters. 



Its colour- 



colours dyed from this insect were frequently called grain, 

 or engrain colours. 



107. When the living insect is bruised, it yields a red 

 colour, the smell of which is not unpleasant. Its taste 

 is bitter, harsh, and pungent. In the dried state, it 

 imparts this smell and taste to water and alcohol, giving 

 to both a deep red colour, which is retained by the ex- 

 tracts made by these infusions. 



108. Kermes is one of the most ancient dyes with . matte r 

 which we are acquainted, but it has fallen greatly into not inferior 

 disuse since the introduction of cochineal. Most of the to that of 

 writers on dyeing admit, that the colour which kermes cochineal, 

 imparts to wool, is inferior in beauty to the scarlet made 



with cochineal ; Dr Bancroft, however, maintains, that 

 by employing along with it a solution of tin or nitro- 

 muriatic acid, he procured a scarlet in every respect as 

 beautiful and estimable as any which can be dyed with 

 that insect. This statement deserves attention, as the 

 colour communicated by the kermes is more durable, 

 and spots of grease may be discharged from it without 

 injury. Hellot mentions that the red draperies of the 

 figures represented in the ancient Brussels, and other 

 Flemish tapestries, were all dyed from kermes, and that 

 this colour, after having stood more than 200 years, 

 seems to possess the same brilliancy as at first. Beck- 

 man affirms the same thing with respect to some pieces 

 of tapestry supposed to have been dyed with kermes 

 about the twelfth century. Dr Bancroft states, that the 

 decoction of kermes exhibits, in almost every case, the 

 same appearances with the different chemical agents as 

 cochineal : and he has accordingly concluded, that the 

 colour of both is " exactly similar." 



1 09. The coccus polonicia is a small round insect, si- Coccus p. 

 milar to the kermes, and employed for nearly the same l n ' cus - 

 purpose's. It is found adhering to the roots of a species 



of polygonum (sctcranlhus pereanis"). Before the intro- 

 duction of cochineal caused the use of it to be abandoned 

 in Europe, it was chiefly collected in the Ukraine and 

 other provinces of Poland, under the name Czerrviec. 

 The juice of the coccus polonicus is still employed as a 

 dye by the Turks and Armenians, particularly for wool, 

 silk, and horse hair. The women also use it to colour 

 their nails. 



110. Several other insects might be noticed which af- 

 ford a red colour, and some of them have been employ- 

 ed for that purpose in Europe ; but the advantages of- 

 fered by cochineal have entirely superseded their use, and 

 caused them to fall into neglect 



111. Lac is a colouring matter, of animal origin, ha- Lac. 

 ving a colour more or less red. It is produced in the 

 East Indies by the coccus lacca, a small winged insect, 

 and is generally deposited on the small branches of the 

 croton laccifernm. " The fly is nourished by the tree, 

 and there deposits its eggs, which nature has provided 

 with the means of defending from external injury, by a 

 collection of this lac, evidently serving the twofold pur- 

 pose of a nidus and covering to the ovum and insect in 



its first stage, and food for the maggot in its more ad- 

 vanced state. The lac is formed into complete cells, 

 finished with as much regularity and art as a honey- 

 con.!), but differently arranged. The flies are invited 

 to de|>osit their eggs on the branches of the tree, by 

 besmearing them with some of the fresh lac, steeped in 

 water, which attracts the fly, and gives a better and 

 larger crop. The egg, which is about tie size of an 



