DYING. 
fides; and it feems to be owing to this clrcumfiance, or 
to their poffeffing fome alperities like the filaments of 
wool, that cotton greatly irritates and inflames wounds, 
ulcers, Sec. if applied to them inftead of lint, from which 
they differ totally in this refpeft; and perhaps the parti¬ 
cular flrudture which occafions this difference, alfo oc- 
cafions fome in the conformation and number of their 
pores, to which alone can be aferibed the difpofition 
which cotton manifefts to admit and retain colours better 
than linen, though not fo well as wool and (ilk, becaufe 
its vegetable nature does not afford it equal attraction for 
colouring matters. M. le Pileur d’Apligny endeavoured 
to explain the caufe why colours are lefs durable when 
dyed in filk, cotton, and linen, than in wool, by fuppofing 
that the pores of the three firft of thefe fubdances were 
fmaller than thofe of wool; and that therefore colouring 
particles could not enter into them fo eafiiy and freely 
as into thofe of wool. But the very reverie of this fiup- 
pofition feems true, there being little difficulty in making 
filk, cotton, or linen, imbibe colours, even when topi¬ 
cally applied cold, without any artificial dilatation of 
their pores, which is neceffary in the dying of wool. The 
real difficulty, therefore, is not in making them imbibe, 
but in making them retain , the colouring particles when 
imbibed; becaufe, being admitted fo readily into their 
undilated pores, they cannot be afterwards compreffed 
and held therein by any contraction of thefe pores, as is 
done in thofe of wool. We know that it requires twice 
as much cochineal to produce a crimfon on filk, as on 
wool ; which is a proof that it can take up a greater 
quantity, and confequently that its pores are at lealt dif¬ 
fidently large and acceffible : we know alfo, that un¬ 
bleached cotton is always preferred for dying the Turkey 
red, it being found to retain the colour mod permanently ; 
doubtlefs becaufe its pores or interftices are lefs open be¬ 
fore than after the operation of bleaching. This is alfo 
the cafe of raw or unfeoured filk, which, as the ingenious 
Mr. Henry of Manchefter obferves, is more eafiiy and 
permanently dyed than that which has palled the procefs 
of whitening 1 and fcouring: and indeed the opennefs of 
the pores of cotton and linen, and their confequent readi- 
nefs to imbibe, both colouring particles, and the earthy 
or metallic bafes employed to fix mod of them, are cir- 
eumdances upon which the art of calico-printing is in a 
great degree founded. To prepare and difpofe cotton 
for receiving colours by dying or calico-printing, it is 
ufinally boiled in water, with a portion of vegetable or 
foffil alkali, for about two hours, and afterwards rinced 
in clean watery or it may be foaked in water, acidulated 
with about one-fiftieth of its weight of fulphuric acid, 
and afterwards rinced thoroughly in a clear dream of 
ivater. 
It appears, however, that what is now termed animali- 
fation, or immerfing the cotton or thread in a preparation 
faturated with fome kind of animal matter, is by far the 
bed means of inducing thofe fabrics to receive and retain 
the dye. A proof of this has been recently given by 
Giobert to the academy of Turin, in his memoire “ on 
the animalifation of flax and cotton;” and another in¬ 
dance has been adduced by Van Mons, who dates, “ that 
he boiled fome potalli and lime, in order to whiten fome 
linens, into which he accidentally put a few oyjler-fhdls ; 
when, to his furprize, he found that thofe pieces of linen 
immediately took a permanent dye, from colours which, 
without the agency of the oyder-ffiells, would have been 
carried off by mere waffiing in cold water.” 
Cotton may be dyed Blue by the following procefs: 
one part of indigo, one part of green fulphat of iron, and 
two parts of quicklime, are flirred into a fufficient quan¬ 
tity of water. The folution is at fird green, but it gra¬ 
dually affumes a yellow colour, and its furface is covered 
with a Alining copper-coloured pellicle. The cloth is 
to be allowed to remain in the folution for five or fix 
minutes. When taken out it has a yellow colour; but, 
on expofure to the atmofphere, it foon becomes green, 
Vol. VI, No. 339 “ 
157 
and then blue, ip confetjuence of the abforption of oxy¬ 
gen. The indigo, in this procefs', feems to be deprived 
of a greater quantity of oxygen than is neceflary to reduce 
it to the date of green pollen. Mr. Hauflman has ob- 
ferved, that the cloth acquires a much deeper colour, 
provided it be plunged, the indant it is taken out of the 
dying vat, into water acidulated with fulphuric acid. It 
is ufual to dip the cloth into a fucceffion of vats, varioufly 
charged with colouring matter; beginning with the vat 
which contains lead colouring matter, and palling gra¬ 
dually to thofe which contain mod. By this contrivance 
the cotton is dyed more equally than it probably would 
be, if it were plunged all at once into a faturated folution 
of colouring matter. To give cotton a very beautiful 
blue colour, the cold vat of Mr. Guhliche is much re¬ 
commended. This vat is compofed of a pound of indigo, 
three pounds of quicklime, three pounds of Englifh vi¬ 
triol, and a pound and a half of orpiment. The indigo 
Ihould fird be carefully ground and mixed with water, 
put into a wooden vat and diluted with water to a proper 
degree, according to the intenfity of the colour defired ; 
the lime is then to be added, and the mixture well flirred, 
covered up, and left at red for fome hours, when the vi¬ 
triol reduced to powder is to be added, the whole well 
flirred, and the vat covered ; fome hours after, the orpi¬ 
ment in powder is to be thrown in, and the whole again 
left at red for fome hours ; after this, the mixture is to 
be flirred, and left to fettle until the fupernatant liquor 
appears clear, when the flower which covers it is put 
afide ; the cotton is then dyed, after having been pre- 
vioufly dipped in warm water. When taken out of the 
bath, it is waflied in a dream of water and dried. When 
the bath becomes turbid, it is left to fettle till it grows 
clear, a precaution effentially neceflary for lighter fliades ; 
and when it begins to be exhauded, one-third of the in¬ 
gredients are added, proceeding as at fird. In proportion 
as the vat is exhauded, the fliades become lighter. This 
vat lerves equally well for filk and thread. 
To dye cotton Yellow, it is neceffary to begin by 
fcouring it in a bath prepared with the ley of the allies 
of green wood ; it is then waflied, dried, and alumed w ith 
one-fourth of its weight of alum; after twenty-four hours 
it is taken out of the aluming, and dried without being 
waflied. A weld bath is then prepared, with the pro¬ 
portion of a pound and a quarter of weld for each pound 
of cotton: in this the cotton is dyed, by being turned 
and wrought in it until it has acquired a proper fliade; 
it is taken out of this bath to be foaked for an hour and 
a half, in a folution of fulphat of copper or blue vitriol, 
iii the proportion of one-fourth of the weight of the cot¬ 
ton ; it is then thrown, without being waflied, into a 
boiling folution of white foap made with the fame pro¬ 
portions; after being well flirred, it is boiled in it for 
nearly an hour, then waflied and dried. But if a dill 
deeper yellow be required, the cotton is not alumed, but 
two pounds and a half of weld for each pound of cotton 
are employed, to which a drachm of verdegris mixed 
with a part of the bath is added; in this, the cotton is 
dipped and worked, until it have acquired an uniform 
colour; it is then taken out of the bath, that a little ley 
of foda may be poured in; returned into the bath and 
kept there for a full quarter of an hour, when it is taken 
out, wrung, and dried very carefully. A lemon colour 
is dyed by the fame procefs,.except that only one pound 
of weld is employed for each pound of cotton, and that 
the proportion of verdegris may' alfo be diminiflied, or 
even entirely omitted, aluming being fubdituted in its 
dead. The fliades of yellow may thus be varied in many 
different ways. For an orange colour, anotta is ufed ; 
this fubdance mud be ground while it is kept moiflened, 
boiled in water with double its weight of alkali, left to 
fettle for half an hour, and the clear liquor put into a 
heated veffel; in this the cotton is to be immerfed, when 
it will receive an orange colour. A hot folution of tar¬ 
tar is then to be poured into the bath, fo that it may be- 
S f come 
