DYEING. 
of galls to every pound of thread, and leav- 
ing* them twentj'-foiir hours in the gall 
liq’uor ; after which they are wrung out and 
dried again. About five quarts of the iron 
liquor are then poured into a tub, in which 
the thread is worked by hand, pound by 
pound, for a quarter of an hour, and then 
wrung out and aired. This operation is re- 
peated twice, adding each time a fresh 
quantity of the iron liquor, which should be 
carefully scummed ; after this the thread is 
again aired, w'lung out, washed at the river, 
and dried. 
The thread receives the colour by im- 
mersion in the following bath. A pound of 
alder bark for every pound of thread is 
boiled an hour in a sufficient quantity of 
water ; about half the bath that served for 
the galling, and half as much sumach as al- 
der bark, are then added, and the whole 
boiled together for two hours, and strained 
through a sieve. When the liquor is cold, 
the thread is put into it on sticks, and 
worked pound by pound, airing it from time 
to time ; it is then let down into tlie bath 
again, left in it twenty-four hours, wrung 
out, and dried. To soften this thread, it is 
usual to soak and work it in the remains of 
a weld bath, that has been used for other 
colours, adding to it a little logwood. 
At Manchester, the method used is, to 
first gall the stuff with galls or sumach, then 
to dye it in the iron liquor, and afterwards 
to dip it in a decoction of logwood and a 
little verdegris. This process is repeated 
till a deep black is obtained. It is neces- 
sary to wash and dry after each operation. 
The iron liquor for this process is frequently 
composed of infusion of alder-bark and 
iron. 
M. Guhliche recommends highly the fol- 
lowing solution of iron for dyeing linen and 
cotton. A pound of rice is to be boiled in 
twelve or fifteen quarts of water till wholly 
dissolved; the vessel that contains this 
liquor is to be half filled with old iron made 
red hot, and the whole to be exposed to the 
air and light for a week ; an equal quantity 
of red-hot iron is to be thrown into as many 
quarts of vinegar, which is also to be ex- 
posed to the air and light; after some 
days, the two solutions are to be mixed to- 
gether, and exposed to the air and light for 
another week. The liquor is then to be 
decanted, and kept in a close vessel for 
use. 
The linen or cotton left in this liquor for 
twenty-four hours acquires a good black. 
If the liquor does not contain iron enough, 
a fresh portion should be used, which will 
produce a permanent black. Hiis liquor 
may be advantageously substituted for sul- 
phate ofii'on in dyeing wool or silk, which 
only require to be dipped in a decoction of 
logwood, after being taken out of the bath, 
to give them a beautiful black. 
Berthollet mentions, that iron ought to 
be more oxygenated to unite with cotton or 
linen than with wool or silk; and that 
therefore the longer the iron liquor is ex- 
posed to the air the bett-sr. The place of 
galls, which bear an high price, is frequently 
supplied by oak-bark, oak saw-dust, sumach, 
the cups and husks of acorns, and other as- 
tringents. 
Of dyeing Wool blue. 
Blue may be dyed by woad alone, wbich 
would give a permanent, but not a deep 
blue ; but if indigo be mixed with it, a very 
rich colour will be obtained. 
The following is the method of preparing 
a blue vat, recommended by M. Quatre- 
mere. Into a vat about seven and a half 
feet deep, and five and a half broad, are 
thrown twm balls of woad, weighing toge- 
ther about 400 pounds, first breaking them ; 
thirty pounds of weld are boiled in a cop- 
per for three hours, in a sufficient quantity 
of water to fill the vat ; when this decoc- 
tion is made, twenty pounds of madder, and 
a basket full of bran, are added, and it is 
boiled half an hour longer. This bath is 
cooled wdth twenty buckets of water ; and 
after it is settled the weld is taken out, and 
it is poured into the vat ; all the time it is 
running in, and for a quarter of an hour af- 
ter, it is to be stirred with the rake. The 
vat is then covered up very hot, and left to 
stand for six hours, when it is raked again 
for half an hour, and this operation is re- 
peated every three hours. 
When blue veins appear on tlie surface of 
the vat, eight or nine pounds of quick lime 
are thrown in. Immediately after the lime, 
or along with it, the indigo is put into the 
vat, being first ground fine in a mill with 
the least possible quantity of w'ater. When 
it is diluted to the consistence of a thick 
pa;), it is draw'n off at the lower part of the 
mill, and thrown thus into the vat. The 
quantity of indigo depends on the shade 
of colour required. From ten to thirty 
pounds may be put to the vat now des- 
cribed. 
If on striking the vat with the rake a fine 
bine scum arises, it is fit for use, after being 
stirred twice wiffi the rake in six hours, t« 
