.346 C H E M 
whence-it was firft brought to us; it is called alftq/or- 
ttambucca, St. Martha's voood, Japan, and Sapan wood, 
from the different places which produce it. A frefli de¬ 
coftion of Brazil wood gives a flight reddifh precipitate, 
with fulphuric acid; the liquor is tranfparent, and of a 
yellow colour. Nitric acid makes the liquor yellow alfo ; 
but, if a large quantity be added, it produces a deep 
-orange-colour, and becomes tranfparent after depoliting 
a precipitate nearly fimilar to the above, but more plen¬ 
tiful. The muriatic acid aft's in the fame manner as the 
fulphuric. 
Of Log-wood.— This has different names according to 
the places where it grows molt plentifully; it is'Very com- 
unon in Jamaica, and on the eaft coaft of the bay of Cam- 
peachy. It gives its colour both to aqueous and fpirituous 
menftrua ; alcohol extracts it eafier and more abundantly 
than water. Its dye is a beautiful red, inclining to vio¬ 
let and purple, which is principally obferved in the wa¬ 
tery decoftion, which, if left to itfelf, becomes yellowifh, 
and at laft black; acids bring it to a yellow ; alkalis fix 
.the colour, and bring it to purple or violet. The ful- 
phuric, nitrjc, and muriatic acids, occafion a flight pre¬ 
cipitate, flow in forming. Sulphat of iron turns it im¬ 
mediately of a blue colour, like ink: and makes a pretty 
.coniiderable precipitate of the fame colour. 
Of Dyer’s Weed. —This is the refsda luteola ofLin- 
jiseus ; it is very common, being found in almoft all parts 
of Europe. Tlie decoftion is of a yellow colour inclining 
to brown ; if much water be added, the yellow inclines to 
green. Alkalis darken the colour; acids make it paler. 
Of Yellow Wood.— This is a large tree, ?mrus tinc - 
•toria, growing in the Antilles, chiefly at Tobago. This 
wood is very full of colouring matter; when the decoc¬ 
tion is well impregnated, it is of a deep red yellow ; weak- 
ended with water, it becomes orange-coloured. Acids 
.make it turbid ; alkalis make it ftronger, and almoft red. 
Of Arnotto. —This is a dry hard palte, brownifh on 
the outlide, and of a fine red within. It is brought over 
in lumps wrapped up in leaves, from America, w’here it 
is prepared from the feeds of a tree, bixa orellana, by ma¬ 
ceration in water, and leaving them to fervent. It dil- 
foives much eafier in alcohol than in water; hence it is 
an ingredient in yellow varnifli, where an orange tint 
is defirable. Arnotto is generally mixed with an alkali, 
■which promotes its folution, and gives it a colour lefs in¬ 
clined to red. 
There are fevera! other ingredients proper for produ¬ 
cing a yellow dye ; as, broom, camomile, fenugreek, cur¬ 
cuma, terra merita, fuftic, plant-feed of Avignon, the 
leaves of the willow, the bark and young branches of the 
Italian poplar and of fome other fpecies of poplars, the 
feed of red clover, the’golden rod of Canada, the flowers 
of the Indian pink, the bark of the quercitron, or yel¬ 
low oak of New England, See. The green (hell of wal¬ 
nuts turns brown in very weak oxygenated muriatic 
acid. It is very ufeful in dying, as its colours are very 
agreeable and very halting. 
OJ Sumach, and ether matters which give a fawn- 
colour. —Common fumach is a flirub which grows natu¬ 
rally in Syria, Paleftine, Spain, and Portugal. An infu- 
fion of fumach, which is of a fawn-colour fomewhat in¬ 
clining to green, quickly grows brown in the air. The 
bark of the elder makes a decoftion of the fame colour, 
which grows turbid and brown in the air; with a foiu- 
.fion of alum, it depofits a confiderable yellow precipitate. 
The decoftion of moft vegetables, particularly the 
barks, as of quinquina, &c. the herb patience, fandal- 
wood, &c. give a colour which differs only in certain 
fhades, and with re-agents their charafters differ very lit¬ 
tle from each other. Some colouring matters ar,e folu- 
ble in oils. Orcanet, or the red root of a fpecies of bu- 
glofs, communicates its colour to oil. Alcohol diffolves 
feveral of them ; the green fecula are foluble therein, as 
•well as in oil. 
We may conclude, from what has been faid, i. That 
I S T R Y. 
the colouring parts of plants have an attraftion, in varii 
ous degrees, for oxygen, and are all changed more or 
lefs by that principle. Another proof of this is, that, if 
pieces of apple be expofed under jars, they foon becoma 
black; cuttings of green-wood, the Spanifh tbiftle, arti¬ 
chokes, &c. prefent the fame phenomena. 2. That 
muriatic oxygenated acid changes, and turns them either 
yellow or white. 
Directions for ufing Vegetable Dyes. —To apply 
colours to a ftutf with effeft, it muft firft be prepared and 
difpofed to receive the principal' colour. For this pur- 
pofe it muft be wallied, bleached, and deprived of that 
glutinous matter which protefted it from the deftruftive 
action of the air, while connefted with the animal from 
which it is taken ; and it muft be impregnated with the 
mordant or corrofive, which fixes the colour, and com¬ 
municates fome particular properties. 
For bleaching of cotton, and difpofing it to receive 
the dye, a liquid foap made of oil and foda is uled, by 
which the fluff is-deprived of that glofs or varnifli, which 
would not permit the dye to adhere in a proper manner; 
and its pores are opened, fo that it may the better re¬ 
ceive and imbibe the colouring principle. When the fluff 
is thus prepared, the next thing is to impregnate it with 
the mordant, or that principle which is to fix the colour, 
and which muft fo far alter its nature, that no water, 
foap, nor boiling, can extraft it again. 
When the cotton has undergone thefe _previous opera¬ 
tions, plunge it into a folution of alum, or ol muriat of 
tin, and afterwards put them into the dying-vat. By 
the decompofition which takes place between the mor¬ 
dant and the principle which holds the colour in folu¬ 
tion, the colour is driven upon the bafe of the mordant, 
and adheres to it. To thofe whofe ftudies direft them 
particularly to the art or dying, we would recommend a 
perufal of'Barthollet’s work on the fubject, and feveral 
memoirs of Chaptal, lately printed in the Annales de 
Chimie. See alfo the article Dying, in this Ency¬ 
clopaedia. 
Of FERMENTATION. 
Vegetables differ from minerals principally in this, that 
the latter remain always in their natural ftate, unlefs a 
powerful force breaks their equilibrium ; but the vege¬ 
table may deftroy itfelf by fermentation, which proves 
that the principles of vegetables do not always remain 
in the fame ftate. Three forts of fermentation are dif- 
tinguifhed, the vinous, the acid, and the putrid. Fer¬ 
mentation is a fpontaneous motion in vegetables, tending 
continually to diforganife their parts. 
Vinous Fermentation. —Experience has (hewn,that 
all vegetable matters are not capable of pafling to the 
vinotis fermentation, but that the union of feveral pecu¬ 
liar circumftances is neceffary for this purpofe. Thefe 
conditions are, 1. A faccharine mucilage, This fubftance 
only is capable of pafling'to the vinous fermentation, 
and of forming wine. 2. A degree of fluidity, (lightly 
vifeid. If the vegetable fluid be either too thick, or too 
thin, it will not ferment. 3. A degree of heat, front 
twelve to fifteen degrees of Reaumur’s thermometer, or 
between fifty-five and fixty-five of Fahrenheit. 4. A 
large mafs, in which a rapid commotion may be excited. 
When thefe four conditions are united, the vinous fer¬ 
mentation takes place, and is known by the following 
charafteriftic phenomena. 1. An inteftine motion is 
excited in the liquor, which increafes till the fermenta¬ 
tion is well eftablifhed. 2. The bulk of the mixture is 
quickly augmented, and this augmentation follows the 
progrefs of the inteftine motion. 3. The tranfparency 
of the fluid is diminiihed by opake filaments, which are 
agitated, and carried to every part of the fluid. 4. A 
degree of heat is produced, equal to eighteen degrees, 
(feventy-two and a half Fahrenheit,) according to the 
AbbeRozier. 5. The folid parts, mixed with the liquor, 
rife and float, in confequence of the difengagement oi: 
