DYEING. 
The colours produced 'by logwood, Bra- 
eil, fustic, and yellow wood, may be fixed 
on wool to advantage by the last mentioned 
mordant. The alkali of the soap used in 
fulling is apt to change the colour given by 
the two first of these substances, but this 
is remedied by a slightly acid bath a little 
hot, called the brightening bath, for which 
sulphuric acid is the best ; the colour after 
this is as deep, and frequently much brighter, 
than before the change. Wool dyed by 
means of this mordant, is said to admit of 
being spun into a finer and more beautiful 
thread than that prepared by alum. If the 
sulphate of copper is omitted, move beauti- 
ful colours are produced by fustic and yel- 
low wood, as well as by weld. An orange 
red is given by madder with it, but not so 
deep as with a similar quantity of aluni. 
When sulphate of copper is omitted, the 
wool is said to be much harsher, and the 
mordant prepared without it yields but in- 
different colours with logwood, and in par- 
ticular with Brazil wood. 
Of dyeing Silh violet or purple. 
Silk may be dyed violet in tvv'o different 
modes, the colour produced by the one is 
called the fine colour, and that by the other 
the false, the latter of which is dyed by 
means of archil or Brazil wood. When the 
fine colour is required, the silk must first 
be passed through a cochineal bath, and 
afterwards be dipped in the blue vat. The 
preparation and dyeing of silk with the 
cochineal, are the same as for crimson, 
with the omission of tartar and solution of 
tin, by which the colour is heightened. 
The quantity of cochineal made use of, is 
always proportioned to the required shade, 
whether it be more or less intense ; but the 
usual proportion for a fine violet colour, is 
two ounces of cochineal for each pound of 
silk. Wlien the silk is dyed, it is washed 
at the river, twice beetled, dipped in a 
blue vat more or less strong in proportion 
to the depth of the shade of violet wanted, 
and then washed and dried with the pre- 
cautions which all colours require tliat are 
dyed in this vat. If the violet is to have 
greater strength and beauty, it is usual to 
pass it through the archil bath ; without 
this light shades would be too dull. 
When silk has been dyed with cochineal 
as above directed, only a very light shade 
is requisite for purple ; the shades which 
are deepest are dipped in a weak blue vat, 
but those which are to be lighter, it is suf- 
ficient to dip in water incorporated w4th a 
small quantity of the liquor of the vat, be- 
cause in the vat itself they would acquire 
too deep a tinge of blue, however weak it 
might be. The light shades of this colour, 
as gillyflower, peach-blossom, &c. are pro- 
duced in this manner, by diminishing the 
quantity of cochineal. 
The false violet colour of the greatest 
beauty, is given to silk by archil, of the 
various w'ays used for producing it; the 
bath of which is to have its strength pro- 
portioned to the colour required. The silk 
having been beetled at the river, after 
scouring, is turned in the archil bath on 
tlie skein sticks; and when the colour is 
deemed sufiiciently deep, a pattem is tried 
in the blue vat to ascertain whether it 
takes the violet colour intended to be pro- 
duced. If the shade is of the proper 
depth, the silk is beetled at the river, and 
dipped in the vat in the same way as for 
the fine violet colours ; and less either of 
the blue or of the archil colour is given, 
according as the violet is intended to have 
the blue or red shade predominant. 
A violet colour may be imparted to silks 
by immersing them in water impregnated 
with verdigris, as a substitute for aluming, 
and next giving them a bath of logwood, 
in which they assume a blue colour ; which 
is converted into a violet, either by dipping 
them in a weaker or stronger solution of 
alum, or by adding it to the bath, the alum 
imparts a red shade to the colouring matter 
of the logwood. This violet possesses but 
little beauty, or durability; but if the 
aiumed silk be immersed in a bath of Brazil 
wood, and next in a bath of archil after 
washing it at the river, a coloi r is obtained 
possessing a much higher degree of beauty 
and intensity. M. Decroizilles’ process, 
above related, for dyeing wool, succeeds 
equally well, according to his account, in 
communicating a violet colour to silk. 
Of dyeing Cotton and Linen violet. 
To communicate a violet colour to cot- 
ton and linen, they commonly receive first 
a blue ground in the vat, proportioned to 
the shade required, and are then dried. 
They are afterwards galled with the pro- 
portion of three ounces of galls to every 
pound of stuff, and being left in this bath 
for 12 or 13 liours, are wi’ung out and 
dried again. They are next passed through 
a decoction of logwood, and when tho- 
roughly soaked and taken out, the bath re- 
ceives an addition of two drams of alum, 
and one of dissolved verdigris for every 
