DYEING. 
injure the beauty of the colour. When raw 
silk is to be dyed, that which is naturally 
rvhite should be selected, and the bath 
should be nearly cold; for otherwise the 
alkali, by dissolving the gum of the silk, de- 
stroys its elasticity. Silk is dyed of an 
orange colour by anotta, but if a redder 
shade be wanted, it is procured by alum, 
vinegar, or lemon juice. These colours are 
beautiful, but do not possess permanency. 
Of dying Cotton and Linen yellow. 
In dyeing cotton or linen yellow, the first 
operation is to scour the stuff with a ley 
prepared from the ashes of green wood ; it 
is then washed, dried, and alumed with one 
fourth of its weight of alum : after twenty- 
four hours, it is taken out of the alum 
liquor, and dried without being washed. A 
weld bath is then prepared, by an infusion 
of a pound and a quarter of weld for every 
pound of the stuff, and in tiiis it is dyed by 
being turned and wrought, till it has ac- 
quired the proper shade. It is then taken 
out of the bath, and soaked for an hour and 
a half, in a solution of a quantity of sulphate 
of copper equal to one fourth of the weight 
of the stuff; it is then thrown, without 
being washed, into a solution of soap in the 
same proportions: after being well stirred, 
it is boiled in dt, for nearly an hour, and 
then well washed and dried. 
If a deeper colour is wanted, the stuff is 
not alumed, but two pounds and a half of 
weld are used for every pound of the stuff, 
for each of which a dram of verdegris mixed 
with a part of the bath is added ; in this 
bath it is dipped and worked, till it has ac- 
quired an uniform colour ; it is then taken 
out of the bath, and a little ley of soda 
poured in ; after this it is again returned 
into the bath, kept there a quarter of an 
hour, and then taken out, wrung, and dried. 
Other shades of yellow may be obtained 
by varying the proportion of the ingre- 
dients ; a lemon colour may be procured 
by using only one pound of weld for every 
pound of cotton, and by diminishing the 
proportion of verdegris, or using alum as a 
substitute. 
Dr. Bancroft directs a method for dye- 
ing cotton yellow, which he asserts to be 
much cheaper, and which appears better in 
several respects, particularly as to the mor- 
dant. It is as follows : 
Tlie mordant to be used is the acetite of 
alumeii, formed by dissolving one pound of 
sugar of lead, and three pounds of alum, in 
a sufficient quantity of warm water. In 
this liquor, heated to 100'’, the cotton is to 
be steeped two hours, after being first pro- 
perly rinsed. It is then taken out and mo- 
derately pressed over a vessel, to prevent 
waste of the liquor. It is then dried in a 
stove heat, and after being again soaked in 
the aluminous solution, is wrung out a se- 
cond time and dried : it is then barely wet- 
ted with lime water, and afterwards dried ; 
and if a full and bright colour is wanted, it 
may be necessary to soak the stuff again in 
tlie diluted aluminous mordant, and after 
drying, to wet it a second time with lime- 
water : after it has been soaked for the last 
time, it should be well rinsed in clean wa- 
ter, to separate the uncombined portion of 
the mordant, which might injure the appli- 
cation of the colouring matter. By the 
use of the lime-water, a greater proportion 
of alumen combines witli the stuff, as well 
as a certain portion of lime. 
In the preparation of the dyeing bath, 
from twelve to eighteen pounds of querci- 
tron bark are inclosed in a bag, for every 
hundred pounds of the stuff, varying the 
proportion according to the shade required. 
The bark is put into the water white cold, 
and immediately after the stuff is immersed, 
and agitated or turned in it for an hour or 
an hour and a half, during which the water 
should be gradually heated, and the tempe- 
rature raised to 120'’. At the end of this 
time the heat is increased, and the dyeing 
liquor brought to a boiling temperature ; 
but at this temperature the stuff must only 
remain in it for a few minutes, because 
otherwise the yellow assumes a brownish 
hue. The stuff having thus acquired a suf- 
ficient colour, is taken out, rinsed, and 
dried. 
Many attempts have been made to imi- 
tate the shade of yellow which nankeens 
possess ; but none have hitherto succeeded, 
so as to produce a colour whose difference 
from the real nankeen could not be in ge- 
neral distinguished at first sight; or in the 
very few instances where this was at all 
doubtful, a little wear soon betrayed the 
deception. Chaptal has recommended a 
colour procured from salt of iron for this 
purpose; and in the processes of others, 
iron in general has been the colouring sub- 
stance used ; but a colour from iron has the 
evident defect of getting black stains from 
the least touch of any astringent liquor, to 
which it is perpetually liable wherever tea 
is used. It is therefore useless to insert re- 
ceipts for a colour, which never yet came, 
sufficiently near what it w'as intended, to 
