444 
posed to the air, from which we infer that the 
alkali induces the formation of an acid from the 
colouring matter, but it is unknown whether it 
acts by forming carbonic or a ternary organic acid. 
The operations consist simply of the decomposi- 
tion of the colour and its removal by alkali. But 
as the colour exists in every part of the bundles 
of fibres, and in considerable quantity, its com- 
plete removal is only effected by frequent repeti- 
tion of the operations. 
II. BueEAcHING BY CHLORINE. 
This powerful bleaching agent might be and 
has been employed both in its gaseous state and 
in solution in water, but the former is incon- 
venient in use, acts unequally on the goods, and 
is too dangerous to the health of operatives. The 
latter is more easily regulated and less injurious, 
but the chlorohydric acid produced during bleach- 
ing may be a source of inconvenience. Hence 
chlorited alkali is preferred, as it develops chlo- 
rine in proportion as acid is made to act on it, is 
not detrimental to health, and offers alkaline 
base to neutralize the generated muriatic acid. 
Chloride of lime or potassa is employed, the for- 
mer most usually. One pt. dry chloride of lime, 
as far as regards its bleaching salt, dissolves in 
10 pts. water, but this would be too strong for 
bleaching white grounds, and is only used for 
printing; this bleaching liquid may therefore 
be diluted with 5 or 10 times as much water. 
Chlorine bleaching is performed on cotton, linen, 
and rags. 
Cotton:—Cotton bleached by chlorine is sub- 
jected to the successive action of, 1st, soda-lye, 
2d, chloride of lime, 3d, sulphuric acid, all em- 
ployed in dilute solutions. To remove the wea- 
ver’s dressing, either fermentation or boiling 
with milk of lime and souring are employed. If 
the goods are greasy, fermentation is abandoned, 
and, indeed, boiling water and the lime-bath 
forms at present the usual preparatory step. 
The succession of separate processes 1s various, 
according to the nature of the goods, or their 
destined object, and according to the pleasure or 
experience of the bleacher. The following tabu- 
jar views will present some of these differences : 
1.—Preparatory. 
a. Washing. 
b. Boiling in lime water. 
c. Washing. 
d. Souring. 
e. Washing. 
2.—Bleaching. 
a. Soaking in soda-lye. 
6. Washing. 
c. Chemicking. 
d. Souring. 
e. Washing. 
3.—The same as 2 repeated throughout. 
4,-~Finishing. 
a. Soaking in hot water. 
b. Squeezing and drying. 
1,-—Preparatory. 
a. Boiling with water. 
BLEACHING. 
6. Washing. 
c. Boiling in milk of lime. 
d. Washing. 
2.—Bleaching. ~ 
a. Bucking in soda-lye. 
b. Exposing on grass. 
c. Washing. 
3.—Same as 2 repeated once or twice. 
4,—-Finishing. 
a. Souring. 
b. Washing. 
1.—Preparatory. 
a. Steeping in water. 
b. Fermentation. 
c. Washing. 
2,—Bleaching. 
a. Bucking with weak caustic potash. 
6. Bucking with stronger lye. 
c. Chemicking. 
d. Souring. 
e. Washing. 
3.—The same as 2 repeated, or 
a. Exposure on grass. 
6. Souring. 
c. Washing. 
In the preparatory process, the first steeping 
in hot or cold water removes whatever is soluble 
in water. The lime then dissolves the gluten of 
the paste, forms a lime-soap with grease, or the 
gluten is destroyed by fermentation. If the 
goods had been greasy, the fatty matter is re- 
moved by the following bucking in soda-lye. 
Thus cleansed, the goods are steeped for some 
hours in the bath of chloride of lime, or che- 
micked. The quantity of the bleaching salt va- 
ries in different establishments, and according to 
the goods; 100 lbs. of the latter require about 50 
lbs. of chloride, which is first made into a paste 
with water, and then added to about 300 gallons 
water. From the chloride the goods are imme- 
diately transferred to the sow, or dilute sulphuric 
acid, consisting of one gallon of oil of vitriol to 
from 20 to 40 of water, in which they remain a 
shorter or longer time in proportion to the 
strength of the acid, The action of the acid is 
to develop chlorine from the bleaching salt with 
which the goods are imbued, and to neutralize 
and remove lime. The goods are washed, and 
the bleaching repeated, either by chemicking and 
souring, or by alkali and exposure, until suffi- 
ciently white. 
Chloride of lime may be simply viewed with- 
out reference to chemical theories, as chlorine 
gas combined with lime, so that the sulphuric 
acid, by combining with the lime, expels the 
chlorine, which is the cause of the destruction of 
the colouring matter in goods. But in what 
manner it decomposes the colour has not been 
determined experimentally, although all chemists 
are agreed that it is by its affinity for hydrogen, 
forming chlorohydric acid. Berzelius holds that 
chlorine, with the action of light, or from the 
presence of oxidable substances, decomposes water, 
forming muriatic acid, while the oxygen set free 
combines with another portion of chlorine to 
chlorous acid, or with water to binoxide of hy- 
5 ae ee eee eee 
