BLE 
nearly as large as B. gigantea, and is a na- 
tive of New Holland ; head pale; front 
subferuginous ; the hind margin brown ; 
wing-cases with an abbreviated black line at 
the base* 
BLAZONING, or Blazonry, in heral- 
dry, the art of decyphering the arms of 
noble families. The word originally signi- 
fied the blowing or winding of a horn, and 
was introduced into heraldry as a term de- 
noting the description of things borne in 
arms, with their proper significations and 
intendments, from an ancient custom, the 
heralds, who were judges, had of winding 
an horn at justs and tournaments, when they 
explained and recorded the achievements 
of knights. 
In blazoning a coat of arms, you must 
always begin with the field, and next pro- 
ceed to the charge ; and if there be many 
things borne in the field, you must first 
name that which is immediately lying upon 
the field. Your expressions must be very 
short and expressive, without any exple- 
tives, needless repetitions, or particles. Such 
terms for the colours must be used as are 
agreeable to the station and quality of the 
bearer. All persons beneath the degree of 
a noble must have their coats blazoned by 
colours and metals ; noblemen by precious 
stones, and kings and princes by planets. 
BLEACHING, in the arts, is a process 
that consists of a series of operations, partly 
chemical and partly mechanical, to which 
vegetable and animal fibres are subjected 
for the purpose of discharging their natural 
colour, and thus rendering them white, 
either before or after they have been ma- 
nufactured. Now as almost all the articles 
of clothing are formed of vegetable or ani- 
mal fibres, and as these are for the most 
part required to be made as white as pos- 
sible, either to be worn in this state, or as 
preparatory to being dyed or printed, it is 
obvious that the art of bleaching is one of 
great importance. The substances upon 
which the bleacher is required to exercise 
his art are cotton, flax, hemp, wool, and 
silk. The three former being of vegetable 
origin require a somewhat similar treat- 
ment, which in many particulars differs 
from that which is applicable to the two 
latter. 
The art of bleaching consists, not merely 
in discharging the colour of the thread, but 
likewise in removing the colouring matter 
itself, as otherwise a sensible shade would 
be regained. In the old method this was 
attained by alternate exposure of the thread 
VOL. I. 
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Or cloth tO the action of light, humidity* , 
and atmospheric air, and to an alkaline ley, 
the cloth being macerated in a solution of 
potash, exposed on the field, to the air and 
sun, and frequently sprinkled with water ; 
and these alternate practices being conti- 
nued until the bleaching was complete. In 
the new method, the action of the oxymu- 
riatic acid is substituted for that of the light, 
air, and water; and it answers the same 
purpose by affording oxygen to the colour- 
ing matter, thus impairing the colour, and 
probably rendering the matter soluble in 
the alkaline solution. 
At first this process was performed by* 
exposing the cloth to the action of the 
pure acid in the state of gas. It was found, 
however, to act unequally on the cloth, 
the texture being injured in one part, while 
in another it was imperfectly whitened. 
The solution of it therefore in water waS 
substituted, and even this requires to be 
considerably diluted. The bleaching li- 
quor, according to the directions given by 
Berthollet, is prepared by putting six parts 
of black oxide of manganese and sixteen 
of muriate of soda into a glass, or earthen 
retort, or a leaden bottle, and pouring upon 
them twelve parts of sulphuric acid, diluted 
with nine of water. The retort, or bottle 
is connected by a tube with a receiver, 
designed to retain any common muriatic 
acid that may pass over ; fi'om this vessel 
another tube issues, which is inserted in a 
large wooden cask filled with water. The 
tube descends nearly to the bottom of the 
cask, so that the gas has to rise through the 
whole body of the water at the same time, 
the absorption of it is promoted by the 
motion of a circular frame placed in the 
middle of the cask, and which can be 
turned round at the top. The oxygenated 
acid is thus easily condensed. After the 
first disengagement of the gas has ceased, 
heat is applied to the retort by placing it in 
a §and bath, or if a leaden bottle be used, 
by placing it in a vessel of boiling water. 
So much water is used that the oxygenated 
acid is very weak ; it requires to be stronger 
for coarse than fine cloth, and for linen 
than for cotton ; the average quantity stated 
by Berthollet is 100 quarts for every pound 
of muriate of soda that has been used. The 
cloth to be bleached is prepared by ma- 
cerating it in warm water for some hours, 
to take up what part of the colouring mat- 
ter may be soluble. It is then boiled in 
an alkaline ley, prepared from 20 parts of 
water, and one part of the potash of com- 
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