DIPPING. 
this fate readily contracts - union with animal or vegetable 
ftuffs. On this aly abe! of ha alkalies to diffo ve geosy- 
tion of indigo, and is enfloyed in dyeing thofe goods, the 
ground of which is intended for blue or green. The parts 
meant to remain white, or which have already received fome 
other colours, being covered with a referve or pafte, to pro- 
te& them from the effet ce = dye 
This procefsis very an 
The fecond is employed in n dyeing thofe ssods intended 
to sap a defign or pattern in one or m ades 0 e, 
round, and a called ‘‘ China blue,”’ or gene 
ifh blue, ae procels having 
originated with the calico-printers of this c 
From time immemorial the nations of the. pa appear to 
have poifeffed a mode of dyeing filk handkerchiefs, and 
other articles of drefs, by a rude but fimple procefs, which is 
practifed at aa day, and has been adopted, and continues 
in ufe, in almoft every part of E 
= 
nn 
remain untouched, difplaying a groun y 
other colour, varioufly, and oftentimes - ine eee diver 
fified with flowers of white or yellow, according to the pri- 
mitive colour of the filk. This mode of dyeing handker- 
chiefs was introduced by the Saracens into Spain, where it is 
toa very co nae abl extent. This, in all 
practufe ri a compofition o 
and other pe iba ts, the parts intended to remain white. 
Hence we may date the origin of blue dipping, and though 
the procefs, as may be fuppofed, has been confiderably im- 
roved fince its oo into Europe, yet the ancient 
require to be v 
bolts and ftraps o 
the conftant ie to which, without t precaution, 
they are fubje&t. In general they are lined with lead, and 
though the expence in the firft inflance is four times that of 
wood, they are eventually much cheaper. They need fewer 
repairs, and afford abfolute fecurity againft all lofs by leak- 
age, which, in a drug o collly as indigo, is a cp aaa 
Stone vats have been tried in 
place t Rouen, according to Berthollet, they are con- 
ftructed of a kind of flint-ftone, well fecured beth outfide 
rie oe with a fine cement; and Pileurd’Appligny mentions 
he had feen compofed of large ftone ine {crewed to- 
pethes at the corners, and the joints of which were arate 
er a kind of maftic varnifh. Economy is the aim 
all thefe various conftructions, as it matters Gee aa the 
at is compofed of, povided it will hold the dye ; and thofe, 
in faét, are the cheapeft, whatever they have coft, that fuffer 
the leaft to efcape. 
The fize of the vat varies confiderably in different dye- 
houfes, according to the nature and extent of the ettablifh- 
ment, and the kiad of work they are intended for. Four 
feet wide, fix feet long, and fix or feven fect deep, are the 
dimeafions of a well-proportioned vat, Syme for two 
pieces of calico, or 56 yards of cloth on a fra Much 
{maller than the fize here given are in ufe for fates of Gngle 
pieces, and vats of {till larger dimenfions are employed by 
fome, whote work and cloth require taem one or two feet 
deeper. 
The vats are all funk in the earth, down . a level, or near- 
ly fo, hs the floor of the oo In fome few old efta- 
blihmen , they ftand two fect, or there sae at ie 
, as Is eau lly the ca ale ¢ on the contin 
ale, ‘the frames are hoifted in and out by a al i fafpended 
over the vat, a mo ft awkward and inconvenient Aries 
and with half a? rouble, yas to manage the pui 
The nu ie arrange ae 
eltablith- 
Onés 5 the m in mites much fooner, and ie re~ 
quire cleaning out and peerae ng lefs (essen 
The nature of the indigo vat is fuch, that the indigo is 
revived and precipitated from it whenever it comes in con- 
which, of courfe, moft dino 
a depth fufficient for a _ of the goods 
tal fide-rails at the ed, and form the bafe of 
the frame, and are foraithed with {mall tenter hooks of cops 
per an inch and a half, -or tw wo inches afunder, to which the 
a peg or pin. 
fide, and fo evenly and tightly ftretched, that when ime 
merfed in the vat every part is equally and alike Hel ana to 
the dye, and no one fold can touch another. mber 
of fi is regulated by the fhade of blue required, a when 
finithed, the goods are taken off the hooks and fae to 
the ordinary A aga of wafhing, rinfing, & Th 
folution of i which, as well as ae a cae contains 
it, is generally calle ‘blue vat yers, is made 
with li d copperas, ae in fome Gi with the addition 
of a Gall quantity of nt € proportion of 
all the ingredients of this folution, and in ie treatment of 
the vat, both during, and after working, confift the chief art 
of “ blue dipping,”’ in the management of which, however, 
there is lefs difficulty than in auy other branch of blue dyeing 
4U2 whatcvers 
