Yellow from Quercitron and Alum Mordant. 65 



method is also to be adopted in procuring a dark yellow. 

 The mordanted cloth is then cleared by immersing it in 

 running water. The boiled powder is very rich in dye-stufF. 

 To obtain the dark yellow, for 14 lbs. of mordanted cloth 

 it is only necessary to employ 3 lbs. of quercitron powder, 

 while, for 14 lbs. of cloth 7 lbs. of the fibrous matter 

 which remains after boiling are required. The powder also 

 gives a clearer yellow. 



Dyeing. — On account of the sharp nature of the fibre of 

 the quercitron which sticks to the cloth, and is not easily 

 separated, it is necessary, when one is about to dye with the 

 fibrous part, to place it in a linen bag, and boil it several 

 times with water. This decoction should then be mixed 

 with water, and heated to 65^f . The cloth well moistened 

 and mordanted should then be dyed at a temperature be- 

 tween 110^1 and 122°. When the solution is formed from 

 15 lbs. quercitron bark and 1 lb. lime the yellow is formed 

 very pure. The addition of bran answers still better, as it 

 does not precipitate the colouring matter. The best pro- 

 portion is 2 lbs. quercitron bark to 3 lbs. bran. If the boiled 

 powder is employed, 2 lbs. quercitron powder are used 

 with 6 lbs. bran. Clearing is not required in this colour. 



Properties of quercitron-yellow . — This colour is not very 

 permanent when exposed to the air and light, but it is 

 more permanent than many other yellow colours. 



Boiling soap-suds consisting of 1 lb. soap in 200 lbs. 

 water is coloured yellow without deteriorating the colour. 



Solution of potash makes brownish spots which vinegar 

 makes white. 



Ammonia, lime water, and vinegar produce no change on 

 the colour. 



Lime juice changes the colour into sulphur-yellow ; am- 

 monia destroys the colour again, and restores the original 

 one. 



Tin mordant. No. 1, printed in a strong solution changes 

 the colour into sulphur-yellow. 



Solution of chloride of lime only renders the colour 

 brownish. If a piece of dyed calico be placed in the solu- 

 tion for a quarter of an hour, a dark brown colour is pro- 

 duced passing into nankeen ; so that in this space of time 

 it does not become white. 



