i_ 175 J Idii 



ing manner: one pound of spirits of nitre, (nitric acid,) two ounces oi' 

 sal ammoniac, six ounces of grain tin. The tin, and the sal ammoni- 

 ac, are to be put into a sand-stone pot of sufficient capacity ; upon these 

 pour about twelve ounces of water, then add the spirits of nitre, and let 

 the solution take place. 



This composition contains much more sal ammoniac and of tin, than 

 that which is employed for the scarlet of cochineal upon wool. The 

 composition is added in the proportion of one ounce to a pound of silk, 

 Avhen the galls and the cochineal have been made to boil. The kettle 

 is left to cool a little, by opening the door of the furnace or stove; 

 the silk is put into the vat, and to be worked from five to seven times; 

 after this, the bath must boil during two hours: in that time, care must 

 be taken to work the silks now and then. At the expiration of this 

 time, the fire is to be withdrawn, and the silks are to be wholly im- 

 mersed; they are to be left there five or six hours, and even if the crim- 

 son be died in the evening, they may be left in it till the next morn- 

 ing. By this means they receive a fine half die: they are to be wash- 

 ed, and to get two beetlings, wrung as usual, and then spread upon 

 the perches to be dried. 



Chaptal says, that, by giving silk a ground of yellow, before dying 

 it in the above manner, a poppy, or flame color, may be obtained, as 

 handsome, and more solid and economical than that produced by the 

 use of the carthamus, or bastard saffron.* 



Of Green. 



This color is composed of yellow and blue: it is difficult to give u 

 to silk, by reason of the inconvenience attending the blue bath, which 

 is subject to be checkered, or to take a variegated color which becomes 

 still more perceptible in the green than in the pure blue. In place of 

 applying the yellow on the blue, we give the blue upon the yellow, 

 and proceed thus: 



The boiling of the silk for these colors is the same as for the common 

 colors. After the silk is boiled, it is to be v\ell impregnated with the 

 aluminous water, then rinsed in the river, and distributed in little 

 hanks of four or five ounces. This precaution is necessary to give 

 the yellow ground to all silks in general which are intended to be died 

 green; because the silk being thus distributed, has the advantage of be- 

 ing uniformly died. Weldt is to be boiled as for the yellow, (which 

 see:) and a bath of it prepared with clear water, and to be so strong as 

 to give a good ground of lemon color. The silk is to be worked in the 

 bath, with great attention, because the inequality of color in the ground 

 is easily perceptible in the green: and when we judge that the ground 

 is nearly at its height, some fibres of the silk should be dipped, in or- 

 der to see whether the color has sufficient plenitude or ground: if it 

 has not enough, add the decoction of weld, and make a new trial- 



• chemistry applied to the Arts, p. 466 

 ''■ Dier's ■^veld — Reseda I.ulcola 



