DYING. 
1G2 
families together in the intervals from other labours, and 
affords them, in fome meafure, the fweets of fociety, 
which prefects an opportunity of habituating infancy to 
labour, and of acquiring a means to render old age com¬ 
fortable. At a time when we are every where employed 
in draining and inclofing land, and when the number of 
fmall additional trails of land mud by thefe means every 
day increafe, it is a circumftance meriting attention, that 
the foil fitted for the culture of hemp is that from which 
the waters have been recently drained, and that this pro¬ 
duction is peculiarly adapted for the employment of fmall 
cultivators. 
Flax ought to undergo feveral preparations before it 
is fit to receive the dye. The fird is deeping ; by this 
the bark, which is afterwards to ferve for fpinning, is 
difpofed to feparate. The deeping is an operation of fo 
great importance, both with regard to its influence upon 
the quantity and quality of the produil, and the delete¬ 
rious qualities it may communicate to the air, that it 
may not be improper to give an idea of the principles on 
which it may be conducted. 
It appears that, in deeping, a glutinous liquor that 
holds the green colouring part of the plant in folution, 
and which unites the cortical with the ligneous part, un¬ 
dergoes a degree of putrefaction greater or lefs according 
to the method we employ; for, as M. Rofier has obferved, 
carbonic acid, and inflammable gas, are difengaged. This 
fubltance appears to refemble greatly the glutinous part 
which is diliblved in the juice exprefled from green 
plants, which feparates from the colouring particles when 
it is made to undergo a heat approaching to boiling, 
which putrefies and affords ammoniac by difiillation. 
Although this fubdance be held in folution in the juice 
exprefled from plants, it appears, however, that water 
alone cannot feparate it from the cortical part ; but it is 
on this account that hemp which has been deeped in a 
rapid dream, is deficient in flexibility and foftnefs. If 
the deeping be performed in dagnant and corrupted wa¬ 
ter, the hemp acquires a brown colour ; but beddes this, 
it lofes its folidity, and exhales vapours which produce 
fatal diforders. It appears, then, that the deeping is 
mod advantageoufly performed in pools planted at the 
fides of rivers, fo that the water maybe eafily renewed 
to prevent the putrefaction from being hurtful to the 
hemp or injurious to health, and yet not fufficient to pre¬ 
vent the degree neceffary to render the gelatinous fub- 
fiance foluble in Water. M. Rofier found that the deep¬ 
ing would be performed when the hemp is covered with 
a layer of earth, and lie advifes that method; M. Pro- 
zet has propofed to diffolve a fmall quantity of caudic 
alkali in the water in which it is periormed, to increafe 
its folvent power, and prevent putrefaction ; but it ap¬ 
pears from the experiments of Dr. Home, that the alkali 
retards the operation of deeping, and renders the flax 
brittle. 
While flax is deeping, and during the drying which 
ought to precede and follow it, the green colouring par¬ 
ticles undergo a change fimilar to that obferved in the 
green fubdance of plants which are expofed to the ailion 
of the air and of light; the colour changes to a yellow, 
to a fawn, and even to a brown, in confequence of the 
combudion which is induced. A great part is then fo¬ 
luble in alkalies, without requiring to be any further 
oxygenated; fo that by treating it with an alkaline folu¬ 
tion, we can feparate from it a confiderable portion of its 
colouring panicles, which remain, perhaps, combined 
with a part of the gluten. It is upon the folution of 
thefe colouring particles that the procefs publifhed by 
the prince of St. Sever for obtaining fine lint from hemp 
is founded. He orders the hemp to be lixiviated with a 
folution of two parts of foda to one of lime, afterwards 
to impregnate it with foap to keep it in digedion, to wadi 
it well, and afterwards to comb it. Berthollet defcribes 
an excellent procefs for obtaining fine lint from hemp, 
which is the invention of a clergyman. He deeps the 
hemp as foon as it is taken from the earth : after deep¬ 
ing he feparates the bark by a particular manipulation, 
and by dipping it in a folution of black foap ; he wadies 
it with great care before drying ; the colouring part, 
which is foluble only in alkalies, may dill be diffolved 
and carried away by the water adided by a little foap ; 
the lint then becomes much whiter; it divides more 
readily without doing fo too much ; and we have the 
lixiviations which ought to precede the bleaching. 
Ordinary thread and cloth that is woven contain a co. 
louring fubdance which may be feparated by dmple lixi¬ 
viations ; but there is a portion of this fubdance that is 
truly combined with the vegetable fibres, and which can 
only be feparated by decompofing it by the combudion 
it undergoes in combining with oxygen. Thread lofes 
by the operation of bleaching from a fourth to a third 
part of its weight. In order to difpofe thread to take on 
the dye, it is made to undergo the feveral operations of 
dreding, aluming, and galling, deferibed under the arti. 
cle cotton ; mod, if not all, of the dyes prepared for which, 
may be communicated by the fame proceffes to linen and 
thread, taking care to have them fird well cleaned and 
bleached. 
Of all colours, the dyers experience the greated diffi¬ 
culty in communicating a full, rich, and durable black, 
to linen, and cotton ; or at lead fuch as will redd the 
foap in wafhing. To dye linen or thread black, a folu¬ 
tion of iron is ufed, which is kept in a calk called the 
black cajk. This folution is prepared with vinegar, fmall 
beer, or fmall wine made from the grapes after they have 
been preffed by adding water to them, which is loured 
with rye-meal, or fome other ingredient, in order to pro¬ 
cure an acid liquid at a low price. Pieces of old iron 
are thrown into this liquor, which is left to dand till 
wanted, but never ufed in lefs than fix weeks or two 
months. To this bath adringents are frequently added, 
particularly the decodlion of alder bark, which of itfelf 
lias the property of diffolving the oxyd of iron in a pretty 
large proportion. The method followed at Rouen, for 
dying linen and thread black, as deferibed by M. le Pileur 
d’Apligny, is this : They are fird dyed fky-blue in the vat, 
then wrung out and dried. They are next galled, tiling 
four ounces of galls to every pound of thread, and leav¬ 
ing them twenty-four hours in the gall-liquor, after which 
they are wrung out, and then well dried. The liquor of 
the black calk, in the proportion of about five quarts for 
every pound, is then poured into a tub, in which the 
thread is worked with the hand, pound by pound, about 
a quarter of an hour, when it is wrung out and aired. 
This operation is repeated twice, adding each time a frefh 
quantity of the black bath, which ought to be carefully 
feummed. After this it is again aired, wrung out, waffled 
at the river to cleanfe it well, and then dried carefully at 
the time. When this thread is to be dyed, a pound of 
alder-bark for every pound of thread is boiled for an hour 
in a fufficient quantity of water. About half the bath 
that ferved for the galling, and half as much fumach as 
alder-bark are then added, and the whole boiled together 
for two hours, and then drained through a fieve. When 
the liquor is cold, the thread is put into it on the (ticks, 
and well worked, airing it from time to time : it is then 
let down into the bath again, left in it twenty-four hours, 
wrung out, and dried as before. For the purpofe of foft- 
ening this thread when it is dry, it is cuftomary to foak 
and work it in the remains of a weld-bath that has been 
ufed for other colours, adding to it a little logwood. 
From this it is taken out and wrung, and inftantly put 
into a tub of warm water, into which has been poured 
an ounce of olive-oil for every pound of thread. It is 
then wrung out and dried carefully. 
The fame author defcribes a procefs in which he em¬ 
ploys madder alfo for giving linen and cotton-thread a 
black colour, and which lie confiders as a very fine and 
durable black. In this procefs the thread is firfl: to be 
feoured as ufual, galled, then alumed, and afterwards 
dipped 
