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fiK ells of filk of this colour, they ufe a pound of the 

 flowers of the acacia, about two ounces of the feeds, and 

 four ounces of alum. 



The king-hoang is a fomewhat deeper yellow : to dye this, 

 they ufe the fame ingredients in the fame proportion as in 

 the former cafe ; and when the filk is dry from the dipping 

 in this, they give it a fecond dipping in a flight tinfture of 

 Brafil wood : this brings it to the fine ftrong yellow we 

 fee. 



The hoang, or pale yellow, is made of the fame ingre- 

 dients as the firft, only inftead of four ounces of alum they 

 put in but three ounces : river water is found to be greatly 

 preferable to any other for the extrafting of thefe colours ; 

 but even in that there is great difference, fome doing the 

 bufinefs much better than others. 



The Chinefe are fo expert in judging on this occafion, 

 that they can tell by the tafte of water whether it will or 

 will not do ; and if it tafte faint they know it is faulty ; but 

 they dip the pieces twice into it inftead of once, and the 

 colour fucceeds well. 



The flowers of the acacia, when they have been prepared 

 by roafting in this manner, may be kept all the year round, 

 and employed in dyeing as occafion requires, only there is 

 to be longer boihng for the dried flowers than the frefh 

 ones ; and it is always found that the frefli flowers give the 

 brighteft colour. Obf. fur les Coutum. de I'Afie, p. 254. 

 Greens are ufually made of yellow and blue mixed. 

 With yellow, madder red, and goat's-hair prepared with 

 madder, are made the golden yellow, Aurora, panfy, naca- 

 rate, Ifabella, and chamois colour, which are all cafts or 

 (hades of yellow. 



Mr. Peter Woulfe has given the following receipt for 

 making the yellow dye : — Take half an ounce of powdered 

 indigo, and mix it in a high glafs veffel, witli two ounces 

 of ftrong fpirit of nitre, which fliould be previoufly diluted 

 with eight ounces of water, for preventing the indigo's 

 being fet on fire by the fpirit ; becaufe two ounces and a 

 half of ftrong fpirit of nitre will fet fire to half an ounce 

 of indigo : let the mixture ftand for a week, and then digeft 

 it in a fand-heat for an hour or more, and add four ounces 

 more of water to it ; filtre the folution, which will be of a 

 fine yellow colour. If the indigo be digefted twenty-four 

 hours after the fpirit of nitre is poured upon it, it will froth 

 and boil over ; but after ftanding about a week, it has not 

 that property. 



One part of the folution of indigo in the acid of nitre, 

 mixed with four or five parts of water, will dye filk or cloth 

 of the paleft yellow colour, or of any fliade to the deepeft, 

 and that by letting them boil more or lefs in the colour. 

 The addition of alum is ufeful, as it makes the colour more 

 lafting : according as the folution boils away, more water 

 muft be added. None of the colour in the operation fepa- 

 rates from the water, but what adheres to the filk or cloth ; 

 and confequently this colour goes far in dyeing. 



Cochineal, Dutch litmus, orchil, cudbear, and many 

 other colouring fubftances treated in this manner, will all 

 dye filk and wool of a yellow colour. 



The indigo which remains undiffolved in making Saxon 

 blue, and collefted by filtration, if digefted with fpirit of 

 nitre, dyes filk and wool of all fhades of brown, inclining 

 to a yellow. 



Cloth and filk may be dyed green with indigo ; but they 

 muft firft be boiled in the yellow dye, and then in the blue. 

 Phil. Tranf. vol. Ixi. part i. p. 129, &c. See Dyeing. 



Painters and enamellers make their yellow of mafficot, 

 or, as fome write it, mafticot, which is cerufle raifed to a 

 yellow colour by the fire ; or with yellow ochre. Limners 



II 



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and illuminers make it with faffron, French berries, orca- 

 nette, &c. 



Mr. Boyle tells us a moft beautiful yellow may be pro- 

 cured by taking good quickfilver, and three or four times 

 its weight of oil of vitriol, drawing off, in a glafs retort, 

 the faline menftruum from the metalline liquor, till there re- 

 mains a dry fnow-white calx at the bottom ; on pouriHg a 

 large quantity of fair water on this, the colour changes to 

 an excellent light yellow. 



He fays he fears this colour is too coftly to be ufed by 

 painters, and he does not know how it would agree with 

 every pigment, efpecially oil colours. Works abr. vol. ii. 

 p. 91. SeeViTElOL. 



Branton obferves, that it was anciently the cuftom to 

 paint a man's door yellow, and ftrew his houfe with fait, to 

 declare him a traitor to his king. 



Yellow and other Colouring Matters of Flowers, in Rural 

 Economy, the different colouring matters thus produced. 

 The nature of the colouring matters of flowers has not yet 

 been much examined into. Such colouring matters are in 

 general very tranfient, efpecially thofe of the blue and red 

 kinds. The yellow colouring matters of this fort are faid 

 to be the moft permanent. It is noticed by a late writer, 

 that the carthamus contains a red and a yellow colouring 

 matter ; that the yellow is eafily diffolved by water ; that 

 from the red, rouge is prepared by a procefs which is kept 

 fecret ; that the colours of moft flowers are changed by 

 alkalies to green, and by acids to red ; that an imitation 

 of the colouring matter may be made by digefting folutions 

 of gall-nuts with chalk ; a green fluid is produced, which 

 becomes red by the aftion of an acid ; and that has its green 

 colour reftored by means of alkalies. 



Yellow Copper, in Mineralogy, copper pyrites. See 

 Copper Ores. 



Yellow Earth, a foft yellow mineral fubftance, found at 

 Wehraw, in Upper Lufatia, affociated with clay and argil- 

 laceous iron-ftone : it is fometimes ufed as a yellow pigment. 

 The charafters given of this fubftance do not feem to entitle 

 it to be regarded as a different fpecies from fome of the 

 ochreous clays which occur in the coal-ftrata in England. 

 It is claffed by profeflTor Jamefon with the lithomarge family, 

 and is thus defcribed by him. Its colour is ochre-yellow, of 

 different degrees of intenfity ; it occurs maflive ; it is dull 

 in the crofs frafture, but glimmering in the principal frac- 

 ture. In the large, the fracture inchnes to flaty ; in the fmall, 

 the frafture is earthy. The fragments are tubular, or inde- 

 terminately angular. It becomes fhining in the ftreak ; it 

 is opaque and very foft, pafling into friable ; it foils the 

 fingers flightly, and adheres to the tongue ; its feel is rather 

 greafy ; it is rather light, but the fpecific gravity is not 

 given. Before the blow-pipe, yellow earth is converted into 

 a black and fhining enamel. We have no analyfis of this 

 earth. 



Yellow Tellurium Ore, an ore of tellurium, hitherto found 

 only at Nagyag, in Tranfylvania. See Tellurium. 



Y^i^hovi Coiv-Wheat, in Agriculture. See Weed. 



Yellow Dead Nettle. See Weed. 



Yellow Devil's Bit. See Weed. 



Yellow or French Berries. See Avignon, and Lycium. 



Yellow Fever, an epidemic difeafe of frequent occurrence 

 in America and the Weft Indies. See Fever, Telloiv. 



Veffels arriving in Great Britain or Ireland, or the iflands 

 of Guernfey, Jerfey, Alderney, Sark, or Man, from places 

 where the yellow fever is known to exift, or where it is 

 deemed likely to break out, are fubjefted by various laws 

 and orders of his majefty in council to the rellraint of qua- 

 rantine ; the fame as fhips arriving from countries fubjeded 



tq 



