DYING. 
two hours in a decodtion of nut-galls, and afterwards 
kept for two hours more in a bath compofed of logwood 
and fulphat of iron, kept during the whole time at a 
fcalding heat, but not boiled. During the operation it 
mult be frequently expofed to the air ; becaufe the green 
oxyd of iron, of which the fulphat is compofed, nut ft. be 
converted into red oxyd by abforbing oxygen, before the 
cloth can acquire a proper colour. The common pro¬ 
portions are five parts of galls, five of fulphat of iron, 
and thirty of logwood, for every one hundred of cloth. A 
little acetit of copper is commonly added to the fulphat 
of iron, becaufe it is thought to improve the colour. 
Of BROWN. 
That favourite brown colour, with a caft of yellow, 
which the French call fauve, and to which the Englifli 
writers on dying have appropriated the word fawn , 
though in fadt a compound, is commonly ranked among 
funple colours; becaufe it is applied to cloth by a fingle 
procefs. The fubftances employed to produce this co¬ 
lour are numerous; but walnut-peels are now confidered 
the belt. When firft feparated from the nut, they are 
white internally ; but foon affume a brown, or even a 
black colour, on expofure to the air. They readily yield 
their colouring matter to water. They are ufuall^ kept 
in large calks, covered wirh water, for above a year, 
before they are ufed. To dye wool brown w'i'h them, 
nothing more is neceffary than to fteep the cloth in a de¬ 
codtion of them till it has acquired the wifhed-for colour. 
The depth of the fh.tde is proportional to the ftrength of 
the decoction. The root, as well as the peel of the 
walnut-tree, contains the fame colouring matter, but in 
fmaller quantity. The bark of the birch, alio, and 
many other trees, may be ufed for the lame purpofe.— 
It is very probable, that the brown colouring matter is 
in tliefe vegetable fubftances combined with tan. This 
is certainly the cafe in fumach, which is often employed 
to produce a brown. This combination explains the 
reafon w hy no mordant is neceffary ; the tan has a (Hong 
affinity for the cloth, and the colouring matter for the 
tan: fo that the dye (tuff and the mordant are already, 
in fact, combined together. In cloths, the oeepelt (hades 
are commonly dyed firft, and the lighter ones afterwards ; 
but for woollen yarn, the light ihades are generally dyed 
firft, and the deeper ones afterwards, frefh peels bemg 
added for each parcel. Cloth and yarn thou Id be fimply 
moiltened with warm water befoie they are put into the 
copper, where they are carefully ftirred until they have 
acquired the proper fhade, unlefs they have before had 
an aluming. 
Mr. Berthollet has dyed different patterns of wool with 
decodtion of walnut-peels, adding to one, oxyd or calx 
of tin, to another, oxyd or flowers of zinc, to a third, 
femivitrified oxyd of lead or litharge, to a fourth, oxyd 
of iron. The quantity of decodtion, weight of the pat¬ 
tern, time of boiling, and ail other circumftances, were 
equal, both with reipect to tliefe, and a pattern which 
was dyed as above, without any addition, and intended 
to ferve as a ftandard of comparifon ; the oxyd of tin 
gave a more clear and bright fawn colour, than that of 
the ftandard ; the oxyd of zinc a colour ftill more clear, 
and approaching to an afti-coloured grey ; the oxyd of 
lead, a colour with more of an orange caft ; and by the 
oxyd of iron, a greenilh brown colour was produced. 
Sumach, when employed alone, gives a fawn colour 
inclining to green. Red faunders gives a fawn colour 
with a brow nidi caft inclining to red ; of itfelf however 
it affords little colour, and it is faid to make the woul 
harfh ; but its colouring matter diffolves better when it 
is mixed with other fubftances, Inch as walnut-peels, 
fumach, and galls; belides, the colour which it gives is 
durable, and modifies tlmfe of other fubftances with 
which it is mixed very conveniently. Soot is likewile 
ufed to give wool a fawn colour, or a brown, which is 
more or lefs deep, according to the proportion of that 
Vol.VI. No. 338. 
J 53 
fubftance which is employed ; but foot gives a fading 
colour, becaufe it only attaches itfelf feebly to the wool 
infteud of combining with it ; it renders it harfh, and 
leaves a difagreeable fmell : it is ufed however for 
browning certain colours in fonte very extenftve manu- 
fadtories. 
Of COMPOUND COLOURS. 
Compound colours are produced by mixing together 
two Ample ones ; or, which is the fame thing, by dying 
cloth firft of one fimple colour, and then another. The 
refult is a compound colour, varying in fhade according 
to the proportions of each of the fimple colours em¬ 
ployed. Hence compound colours are exceedingly 
numerous,-varying-almoft to infinity, according to the 
proportions of the ingredients employed. 
Mixtures of BLunand Yellow, or Green. —Dyers 
make green by the admixture of blue and yellow, and 
it is diftinguifhed into a great number of different (hades ; 
but it requires addrefs and experience to obtain this 
colour uniform and without fpots, efpecially in the lighter 
(hades of it. It is poffible to produce green by beginning 
either with the yellow or the blue dye : but the firft 
method is attended with fome inconveniences ; for the 
blue foils the lir.en, and a .part of the yellow being 
diffolved in the vat, changes and makes it green ; the 
fecond method is therefore preferable. It is common to 
employ the paftel vat, but for fome kinds of green, folu- 
tion of indigo in the fulphuric a, id is ufed; and then, 
the blue and yellow are either dyed feparately, or all 
the ingredients are mixed together, to dye by a fingle 
operation. Solutions of copper with yellow fubftances 
may however be employed. The proceifes are thefe : 
It is neceffary that the blue ground be proportioned to 
the green which is defired ; thus for the green like that 
of a drake’s neck, a ground of deep royal blue is given; 
for parrot green, a ground of fky blue ; for verd naiffant , 
a ground of light blue. After the cloths have received 
the proper ground, they are waffied in the fulling-mill, 
and boiled as for common welding, but for the light 
(hades the proportion of falts is diminiflted. Mod com¬ 
monly the cloths intended for the light (hades are boiled 
fir It; and when thefe are taken out, tartar and alum are 
added ; and this pradlice is purfued until we come to the 
cloths intended for the darkeft (hades, more and more 
tartar and alum being conftantly fupplied. The procefs 
of welding is condudted in the fame manner as for yel¬ 
low ; but a larger quantity of weld is employed, unlefs 
for the lighter (hades, which, on the contrary, require a 
ftill fmaller proportion. For the molt part, a fucceffion 
of (hades, from the deepeft to the lighted, is dyed at the 
fame time, beginning with the deepeft, and proceeding 
to the lighted : between each dip, which lads half an 
hour, or three quarters, water is added to the bath. 
Some dyers give each parcel tw o dips, beginning the firft 
time witli the deep (hades, and the fecond with the light 
ones; in that cafe each parcel fttould remain a (liorter 
time in the bath : for the very light (hades, care (hould 
be taken that the bath does not boil. A browning with 
logwood, and a little fulphat of iron, is given to the 
very deep greens. 
But the green obtained by means of a folution of indigo 
in fulphuric acid is known by the name of Saxon green ; 
and it has more brightnefs, but lefs durability, than that 
above defcribed. In the procefs for it a boiling is given 
as for welding, and the cloth is then waffled, fuftic in 
chips encloied in a bag is put into the fame bath, and 
boiled for an hour and a half, then taken out, and the 
bath cooled to a temperature which the hand can (up- 
port ; nearly a pound and a quarter of the folution of 
indigo for each piece of cloth of eighteen ells-which is to 
be dyed, is then added; at firft it is to be turned with 
rapidity, and afterwards (lowly: the cloth is to be taken 
out before the bath boils. It is a proper practice to 
put in only two-thirds of the folution at firft, to take 
R r out: 
