DYEING. 
iwuiids of logwood, and ten pounds of su- 
mach. After having boiled the cloth in this 
bath for three hours, it is taken out, ten 
pounds of sulphate of iron are put into the 
copper, and the cloth is then put into it for 
two hours more. It is then aired, put into 
the bath again for another hour, and after- 
wards washed and fulled. This black is less 
velvety than that of the process first des- 
cribed. 
Black maybe dyed without a blue ground, 
and this is usually done for stuffs of low 
price. In this method the stuff is dyed of a 
brown, or root colour, with green walnut 
peels, or the root of the walnut tree : they 
are then blackened as above directed. 
The proportions used by the English 
dyers are, for every hundred pounds of 
vToollen cloth, dyed first of a deep blue, 
about five pounds of sulphate of iron, five 
pounds of galls, and thirty of logwood. They 
begin with galling the cloth, and then pass 
it tlirough the decoction of logwood, to 
which the sulphate of iron has been added. 
Some recommend fine cloths to be fulled 
with soap suds ; but this operation requires 
an experienced workman to cleanse the 
cloth perfectly of the soap. Many advise 
to give the cloth a dip in a bath of weld 
when it comes from the fulling mill, which 
they say softens it, and fixes the black. 
Lewis says, the weld bath is totally useless 
when the cloth has been treated with soap- 
suds, though in other cases it may be of ad- 
vantage. He ascribes its effects entirely to 
the alkali with wliich the dyers commonly 
prepare its decoction. 
The leaves of the uva ursi may be em- 
ployed instead of gafis. They must be care- 
fully dried in autumn, so that they may re- 
main green. When they are to be used, 
100 pounds of wool are boiled for two hours 
with sixteen pounds of sulphate of iron and 
eight of tartar: the day following the cloth 
is to be rinsed as after aluming: 150 pounds 
of uva ursi are then to be boiled in water 
for two hours, and after their being taken 
out, a little madder is to be added to the 
liquor, at the same time putting in the cloth, 
which is to remain there an hour and a half, 
or an hour and three quarters, after which 
it is to be rinsed in water. This pro- 
cess gives a pretty good black to blue cloth, 
but only a deep brown to white : the mad- 
der and tartar are supposed by Lewis to be 
useless. 
Of dyeing Silk black. 
It is necessary to cleanse silk that is to 
J»e dyed from the substance which adheres 
to it, called its gum ; for though raw silk 
takes the dye with more facility, the colour 
is much less intense, and less durable, 
than when the silk is scoured; which is 
done by boiling it four or five hours witli a 
fifth of its weight of white soap, after which 
it is beetled and carefully washed. 
After being cleansed the silk must be 
galled ; for which nearly three-fourths of its 
weight of galls are boiled for three or four 
hours, but their quantity must depend on 
the kind used ; after boiling, the liquor is 
left at rest for two hours, that the galls may 
subside ; the silk is then put into the bath, 
and left in it from twelve to thirty-six hours ; 
it is then taken out, and washed in tlie 
river. Silk is capable of combining with 
much of the astringent matter of the galls, 
which attracts the colouring matter in pro- 
portion ; therefore, when what is called an 
heavy black is required, it is allowed to re- 
main longer in the gall liquor, the galling is 
repeated, and it is dipped in the dye a 
greater number of times, and left in it also 
for a considerable time. This method nei- 
ther improves the dye nor the silk ; but is 
merely used to give profit to the vender 
where silk is sold by weight. 
Silk dyers preserve the black bath for 
silk for several years; when its effect be- 
comes weak, it is renewed by adding more 
of its ingredients, and when the grounds 
accumulate too much they are taken out. 
While the silk is preparing for dyeing 
the bath is heated, taking care to stir it oc- 
casionally, that the grounds, which fall to 
the bottom, may not acquire too much heat ; 
it should never be heated so as to boil. 
Gum and solution of iron are added, in pro- 
portions depending on the different proces- 
ses used ; and when the gum is dissolved, 
and the bath near boiling, it is left to settle 
for about an hour. The silk is then dipped 
into it, being in general at first divided in- 
to three parts, each of which is put in suc- 
cessively. Each part is afterwards wrung 
gently three times, and hung up in the air 
after each wringing. The action of the air 
deepens tlie shade, and the wringing out the 
liquor prepares the silk to imbibe a fiesh 
quantity. 
After this the bath is again heated, and 
as much gum and sulphate of iron is put in 
as at first. The operation is repeated twice 
for light blacks ; but for the heavy blacks 
three times ; and after the last the silk is 
left in the bath for twelve hours. Sixty 
pounds of silk are coramonlv dyed at one 
operation . 
