BLANCHING. 
442 
not well be reduced without the application of 
lunar caustic. All cattle, therefore, ought to be 
kept at a distance from a diseased animal; and 
the human attendant on the latter ought tho- 
roughly to protect any spot of his hands which 
may be sore or scratched. Sheep affected with 
blain require to be treated in nearly the same 
manner as cattle; only the proportion or strength 
of medicated drinks must be reduced to suit the 
weaker power of the animal.—Olater’s Cattle Doc- 
tor.— Lisle’s Husbandry—Spooner on Sheep.— 
Youatt on Cattle. 
BLANCHING. A horticultural operation for 
rendering the stems and leaves of certain escu- 
lent plants mildly flavoured, crisp, and tender. 
Plants which grow in the dark are destitute of 
| verdure and of the stronger kinds of odours, which 
belong to plants of the same species grown in 
the light; they are also much less combustible, 
and comparatively free from oils and resins; and, 
if they are of the group whose leaves or roots are 
eaten raw, they are more saccharine, less acrid, 
and, in all respects more agreeable to the palate. 
A method of blanching practised upon lettuces 
and upon such of the cabbage genus as do not 
| boll, is to tie the leaves close up in summer ; and 
this method both improves the flavour of the 
leaves, and accelerates the period of their fitness 
for use. A method practised upon celery, en- 
dive, and dandelion, is to earth them up to their 
top in winter; and this not only blanches them, 
but protects them from frost. A method prac- 
tised with leeks, is to transplant them, when 
| about six inches high, into deep and half-open 
dibble-holes, cutting away a portion of both the 
roots and the tops of the plants; and this both 
adds greatly to the length of the blanched por- 
tion of the head, and very materially cleanses it 
from the natural pungency and coarseness of its 
flavour. A diseased whiteness in plants or parts 
of plants which ought to be verdant is somewhat 
distinct from blanching, and obtains the name of 
etiolation. See the article Erronation. 
BLAST. Blight in vegetables, or hoove in 
sheep and black cattle. See the articles Burcut 
and Hoover. 
BLASTING OF ROCKS. An operation of 
great importance in the formation of roads, or 
in the breaking up of uncultivated ground. The 
process of blasting rocks, or stones, consists in 
boring’a cylindrical hole, about 10 or 12 inches 
deep, in the rock, by means of a chisel for that 
purpose. The lower part of this hole is filled 
| with gunpowder. The upper part of the hole is 
then filled up with fragments of stone, firmly 
rammed together; a hole being left through 
these materials, by the insertion of an iron rod, 
which is turned round during the operation of 
ramming. This hole is next filled with powder, 
and a match is applied to it in such a manner, 
that the operator has time to run out of the 
reach of the fragments of the rock. This pro- 
cess, which is both tedious and dangerous, is now 
BLEACHING. 
abandoned for one which is more simple and 
effectual, and which consists merely in introduc- 
ing a straw, filled with gunpowder, among the 
powder at the bottom of the cylindrical hole in 
the rock, and filling the rest of the cylindrical 
hole with loose sand. By applying a match to 
the gunpowder in the straw, an explosion takes 
place ; and, instead of the loose sand being driven 
out of the cylindrical hole, as might naturally 
be expected, the rock is completely shivered in 
pieces. 
BLATTARIA. See Muzunt. 
BLAZE. A white mark in a horse’s face. 
BLEA. An obsolete or merely provincial name 
for the alburnum of a tree; also a provincial 
name for a leaden or dusky blue colour. 
BLEABERRY. See WuHortTLEBERRY. 
BLEACHING. The destruction or removal of 
colour from an organic substance, the main mass 
of which is white, is termed bleaching. Thus 
yellow bees’ wax, by a careful exposure to the at- 
mosphere, will eventually become white, without 
any other material change in its properties, as 
the yellow colouring matter does not necessarily 
belong to it. In this sense, some of the dischar- 
ges employed in calico-printing are bleaching 
agents, but we propose confining ourselves in the 
present article to the methods of removing colour 
from organic fibre, such as cotton, linen, &c., 
either to prepare it for receiving other colours 
by dyeing or printing, or to throw it into com- 
merce with a pure white colour. The methods 
formerly pursued, and still practised, consist in 
exposing cotton, Wc., to the action of atmospheric 
agents or sulphurous acid derived from burning 
sulphur, assisted by soap and alkali, but within 
the present century chlorine has become the 
principal bleaching agent, especially for cotton 
goods. We may remark in passing, that the use 
of chlorine for bleaching has been one principal 
cause of the present extensive production and 
consumption of cotton goods, even independently 
of the improvements in machinery which have 
distinguished the last century. 
I. ArmospHeric BLEACHING. 
It is only employed for linen and cotton, the 
latter of which is the simpler and easier. 
Cotton.—Cotton contains naturally a little col- 
ouring matter, which is easily bleached, but as 
this operation is performed on the spun or woven 
goods, the weaver’s dressing, grease, and other 
impurities must be removed at the same time. 
The process consists, Ist, in steeping the cotton 
in water (not too cold), in order to destroy the 
weaver’s dressing by fermentation, which takes 
place in from 1 to 6 days, according to the wea- 
ther and the kind of goods, when it is thoroughly 
cleansed in the dash-wheel, or otherwise. 
The goods are then spread out on the grass, 
and exposed for 2 to 6 days to the action of the 
sun, air, and moisture, sprinkling them occasion- 
ally with water, if necessary; and then bucked 
