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BLEACHING. 
lime; 2d, of that of chlorine; and, 3d, of the com- 
bining the two together. 
1. Lime.—Limestones frequently contain iron, 
clay, and magnesia. Such are not well adapted 
to the manufacture of bleaching powder. Sup- 
posing the limestone to be of the best kind, and 
well burned, the operation of slacking requires 
some attention, for just so much water should be 
used as is sufficient to cause the quick-lime to 
fall to a fine flour. Itis likewise important that 
the lime should be fresh, for otherwise it will 
have absorbed carbonic acid from the air and 
have become proportionally injured. In order to 
effect the perfect slacking, it is perhaps better to 
add a little less than a little too much water. 
2. Chlorine-—This gas may be made either 
with black oxide of manganese and muriatic 
acid, or with the same oxide, and common salt 
with sulphuric acid. The manganese ore should 
contain as much pyrolusite and as little manga- 
nite as possible, since the former contains much 
more oxygen, which is required to oxidize the 
chlorohydric acid, and develop chlorine. The ore 
is reduced by calculation to binoxide. The ore is 
coarsely pulverized, for if in fine powder it is apt 
to form a compact mass at the bottom of the ves- 
sel for generating chlorine. For every 44 pts. of 
binoxide present in the ore, 58 pts. dry common 
‘salt are required, which are well mixed with the 
ore, and the whole thrown into a leaden vessel 
or generator; 140 pts. sulphuric acid, diluted 
with as much water, are then poured into the 
generator. 
Four days are required, at the ordinary rate of 
working, for making good marketable bleaching- 
powder. A more rapid formation would endan- 
ger an elevation of temperature, productive of 
muriate of lime, at the expense of the bleaching 
quality. But skilful manufacturers use an alter- 
nating process, by piling up the wooden trays 
containing slacked lime only in alternate shelves 
in each column. At the end of the two days the 
distillation is intermitted, and the chamber is 
laid open. After two hours the workman enters, 
to introduce the alternate trays covered with 
fresh hydrate of lime, and at the same time rakes 
up thoroughly the half-formed chloride in all the 
others. The door is then secured, and the cham- 
ber, after being filled for two days more with 
chlorine, is again opened, to allow the first set of 
trays to be removed, and to be replaced by others, 
containing fresh hydrate, as before. 
A good dry chloride of lime should be a white, 
uniform powder, possessing a faint odour of chlo- 
rine, slowly deliquescent in the air, forming a 
smooth paste with a little water, and dissolving 
in 20 pts. water with little residue, which solu- 
tion should react alkaline. It should always 
have an excess of lime to protect it as far as pos- 
sible from decomposition, and to neutralize free 
muriatic acid, which may be generated. 
A liquid chloride is often preferred to the dry 
powder by calico-printers, especially where it is 
BLEEDING. 447 
manufactured in their own establishment. The 
arrangement above given may be employed for 
liquid chloride by passing the chlorine through 
tubes into milk of lime, consisting of 3 or more 
pts. lime to 100 water. The tubes should not 
dip deeply in the liquid, and the milk should be 
stirred up frequently. This solution of chloride 
tests stronger than the dry chloride from an 
equal quantity of lime, but, per contra, it is more 
liable to decomposition and must be used a short 
time after its preparation. 
BLEEDING. The surgical letting of blood, 
for the alleviation or cure of disease. It is one 
of the readiest and most powerful remedies for 
the cure of various disorders, particularly those 
of the inflammatory class; yet though one of the 
simplest, most common, and most useful of reme- 
dial operations, it is very often both unseasonably 
and bunglingly performed. In all acute and rapid 
diseases, whether in the horse, the cow, or other 
valuable domestic animals, it is of the greatest 
importance, and ought in every case to be prac- 
tised. In colds and inflammation of the lungs, 
it is always required, and is the principal remedy 
which can be used. In colic, suppression of 
urine, and inflammation of the bowels, it cannot 
do harm but is generally serviceable, and ought 
always to be applied. In inflammation of the 
eyes, the brain, or any other organ, whether oc- 
casioned by external or by internal causes, it is 
invariably suitable and ought to be promptly 
practised. : 
In the case of neat cattle, in particular, all 
swellings of the joints and all inflammatory 
diseases, no matter of what organ or from what | 
cause, may be reduced by general bleeding ; blain 
may be attacked by general, but more success- 
fully by local bleeding ; enlargement of the glands 
of the throat or of those between the jaws, should 
be reduced by bleeding in order to arrest con- 
sumption or other dangerous diseases of the 
lungs ; feverishness or constipation as accompani- 
ments of the yellows ought to be attacked by | 
bleeding ; contusions on the head or any wounds 
or bruises whatever which are likely to occasion 
inflammation involve a necessity for bleeding ; and 
violent cold or catarrh which resists the power of 
a few antifebrile drinks, may be cured by bleed- 
ing. 
Horses which stand much in the stable and 
are full fed have greater need of bleeding under 
any ailment than such as enjoy daily exercise ; 
and when their eyes are heavy and inflamed, or 
when their lips or the interior parts of their 
mouth are unduly red, or when they mangle their 
hay and seem unusually heated, they are in par- 
ticular need both of being bled and of having 
their diet lowered. The bleeding of young horses 
when they are shedding their teeth, relieves their 
pain and frees them from feverish heats. Bleed- 
ing is sometimes desirable in spring to decrease 
the ardour and strength which then characterize 
the blood; and it is sometimes necessary in sum- 
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