[Footnote 222: The strengths of the solutions, when not otherwise stated,
are about the same as those given under COTTON (_antè_).]
_Obs._ The chief difficulty in bleaching linen arises from the fact that
its colouring matter is insoluble in acid or alkaline solutions until it
has been long acted upon by light, air, and moisture, as in the common
process of grass-bleaching. Chlorine hastens the operation; but,
unfortunately, it can only be employed towards the end of the process; as
when earlier used, the colour of the raw cloth becomes set, and
irremovable. To obviate this difficulty Mr F. M. Jennings, of Cork, has
lately[223] introduced the joint use of an alkali and an alkaline
hypochlorite (chloride) in the place of the ordinary chloride of lime. He
prepares a bath of solution of soda at 5° Twaddle, which he raises by the
addition of chloride of soda (or of potash) to 6 or 7°, and in this he
steeps the cloth (after the first bucking and souring) for some hours,
heat, or constant squeezing between rollers, being had recourse to, to
facilitate the action. Souring and washing follow, when the goods are
again put into the alkaline and chloride bath, as before; after which they
are soured, and bucked again with soda. These last three operations are
repeated until the cloth is almost white, when crofting for one half to
one fourth the time required by the usual method renders it fit for the
final bucking, and finishing. Indeed, it is said that if the process be
very carefully managed it renders crofting unnecessary.
[Footnote 223: Patent dated 1859.]
Raw linen loses about 1-3rd of its weight in bleaching.
III. =Silk=:--Silk is usually bleached by first steeping it, and then
boiling it in solutions of white soap in water, after which it is
subjected to repeated rinsings, a little indigo-blue, or archil, being
added to the last water to give it a pearly appearance. When required to
be very white (as for gloves, stockings, &c.), the goods are cautiously
submitted, for 2 or 3 hours, to the action of the fumes of burning
sulphur, and then finished by rinsing, as before.
_Obs._ Boiling or sulphuring is not required for the white silk of China.
Raw silk loses from 4 to 5 _oz._ per _lb._ by bleaching.
IV. =Wool=:--In bleaching raw wool it is first deprived of the yolk or
peculiar natural varnish with which it is covered. For this purpose it is
steeped and stirred for about 20 minutes in rather warm water (135°--140°
Fahr.), either with or without the addition of 1-4th part of stale urine;
after which it is placed in baskets to drain, and soon afterwards
thoroughly rinsed in a stream of water, when it is again allowed to drain,
and it is hung up to dry. The further operations depend on circumstances,
wool being sometimes whitened in the fleece, or in the yarn, but still
more frequently and extensively not till woven. When it is intended to
send it in the first two forms white to market, it is hung up or spread
out, whilst still wet, and sulphured (see _below_); after which it is
either at once rinsed for some time in cold water, or is previously
treated with a very weak bath of soft soap.
In the case of woollen fabrics the operations of purifying or whitening
the wool, beyond the removal of the yolk, are, for the most part, mixed up
with the weaving and working of it. The pieces leave the hands of the
weaver of a dingy grey colour, loaded with oil, dirt, and dressing. They
then pass to the fulling-mill, where they are treated with fuller's earth
and soap, often preceded with ammonia or stale urine, after each of which
they are well washed out or scoured with cold water, and are then ready
for the dyer. When it is intended to obtain them very white, or to dye
them of a very delicate shade, they are commonly sulphured; after which
they are washed or milled in cold water for some hours, a little finely
ground indigo being added towards the end, to increase their whiteness; an
addition also made when the cloth is sufficiently white without the
sulphuring process.
The usual mode of SULPHURING woollen goods is to hang them up on pegs or
rails, or, in the case of fleece-wool, to spread it about, at the upper
part of a close, lofty room or chamber, called a sulphur-stove. In each
corner of this room is set a cast-iron pot containing sulphur, which,
after the introduction of the goods, is set on fire, when the door at the
lower part of the chamber is shut tight and clayed. This is commonly done
over-night; and by the morning, the bleaching being finished, the goods
are removed, washed, and azured.
Sulphuring, unless very skilfully managed, imparts a harsh feel to woollen
goods, which is best removed by a very weak bath of soap-and-water
(lukewarm); but the action of soap in part reproduces the previous
yellowish-white tinge. Milling with cold, or lukewarm water, tinged with
indigo, is the best substitute.
_Obs._ Raw wool loses from 35 to 45% of its weight by scouring, and 1 to
2% more in the subsequent operations of the bleacher; the loss being in
direct proportion to the fineness of the staple.
[asterism]The above are the four principal applications of the art of
bleaching; but, in technical language, the words bleaching, bleacher,
bleachery, bleach-works, &c., when employed alone, are understood to have
reference only to cotton and linen. This has arisen from the enormous
extent of these manufactures, and from the process of bleaching them
forming a business entirely distinct from that of weaving, dyeing, or
printing them. The following, with the exception of the first, are of
comparatively minor importance and interest:--
V. =Materials for Paper=:--Old rags for the manufacture of paper, and
paper-pulp, are now almost universally bleached with chlorine or chloride
of lime; the former being generally used in France, and the latter in
England. The process usually consists in (1) boiling in an alkaline lye to
remove grease and dirt, (2) washing, (3) pressing, (4) deviling or
tearing up the pressed cake into fine shreds or pulp, (5) chemicking, with
agitation, for about an hour, in a clear solution of chloride of
lime,[224] followed by (6) washing, (7) souring with dilute hydrochloric
acid at 1 or 2° Tw., or treatment with a solution of some antichlor, or
both, and (8) a final washing and pressing. For the common kinds of paper,
the operations included in No. 7 are omitted; but unless the whole of the
lime-salt be removed from the pulp, the paper made of it is liable to turn
brown and become rotten by age. In some cases rags are bleached before
being divided and pulped. Cotton-waste is bleached in a similar way to
rags.
[Footnote 224: The 'strength' varies with the colour and quality of the
rags. From 2 to 4 _lbs._ per _cwt._ of rags is a common proportion; but
for dyed and printed rags as much as 7 or even 8 _lbs._ per _cwt._ are
often employed. It is better, however, to prolong the process with a
weaker solution, than to hasten it by using the chloride in excess. Large
rectangular cisterns of wood, or of slate, are commonly employed as the
bleach-vessels. Cisterns of wood, or brick-work lined with gutta percha or
with asphalto-bitumen, are employed in some paper-mills, and answer
admirably.]
In France, the chlorine, in a gaseous form, is passed from the generators
into the bleach-cisterns containing the pulp, which in this case must be
fitted with close covers.
=VI. Printed Paper=, as Books, Engravings, Maps, &c.--These when stained
or discoloured may be whitened by (1) wetting them with pure clean water,
(2) plunging them into a dilute solution of chloride of lime, (3) passing
them through water soured with hydrochloric acid, and then (4) through
pure water until every trace of acid be removed. This process may be
further improved by further dipping them into a weak solution of some
antichlor, and again washing them, before finally drying them. It is only
rare and valuable original works or specimens of art that are worth this
treatment, which, owing to the very nature of paper, requires considerable
address to manage. In many cases a sufficient degree of renovation may be
effected by simply exposing the articles, previously slightly moistened,
to the fumes of burning sulphur, followed by passing them through a vessel
of pure water.
=VII. Straw, Straw-plait=, and articles made of them, are, on the large
scale, usually bleached by (1) a hot steep or boil in a weak solution of
caustic soda, or a stronger one of soda-ash, followed (2) by washing and
(3) by exposure to the fumes of burning sulphur. To effect the last, the
goods are suspended in a close chamber connected with a small stove, in
which brimstone is kept burning. On the small scale, a large chest or box
is commonly employed. A piece of brick, or an old box-iron heater, heated
to dull redness, is placed at the bottom of an iron crock or earthen pan,
a few fragments of roll sulphur thrown on, the lid instantly closed, and
the whole left for some hours. Care should be taken to avoid inhaling the
fumes, which are very deleterious as well as disagreeable and annoying.
Straw goods are now also frequently bleached by the use of a weak solution
of chloride of lime, or of water strongly soured with oxalic acid or even
oil of vitriol, followed by very careful rinsing in clean water; but here,
as in the former case, the natural varnish, dirt, grease, &c., must be
first removed by alkalies or soap, to enable the chlorine or acid to act
on the fibres.
=VIII. Wax.= Wax is bleached by first melting it at a low temperature in a
cauldron, from whence it is allowed to run out by a pipe at the bottom
into a capacious vessel filled with cold water.
This vessel is fitted with a large wooden cylinder, which turns upon its
axis; and the melted wax falls upon this cylinder. The surface of the
cylinder being always wet, the wax does not adhere to it, but becomes
solid, assuming the form of ribbons as it does so, and in this shape
becoming distributed through water in the tub. The wax is then removed and
placed upon large frames stretched upon linen cloth, which are supported
about 18 inches above the ground, and erected in a situation exposed to
the air, dew, and sun. The several ribbons thus placed on the frame should
not exceed an inch and a half, and they ought to be so moved about from
time to time as that each part may be equally exposed. If the weather be
favorable the wax will become white in a few days. It is again remelted,
formed into ribbons, and exposed as before. These operations are continued
in until the wax is completely bleached, after which it is melted and run
into moulds.
_Concluding Remarks._ The theory of bleaching, notwithstanding the giant
strides of chemistry during the last 20 years, remains still unsettled;
and hence the processes employed are still, for the most part, empirical.
It appears probable that chlorine acts by uniting with the hydrogen of the
water, or of other compounds present, or probably with that of both, and
that it is the oxygen thus liberated, and whilst in the nascent state,
that is the true operative agent. Hence bleaching by chlorine, or by the
hypochlorites, may be regarded as an oxidation of the colouring matter;
but whether the chlorine or the oxygen effects this oxidation is of little
practical importance--the result being the same--the destruction of the
compound, and the removal of the colour that depends on its existence. It
is doubtful whether the bleaching power of sulphurous acid is due to it as
an oxidising or a deoxidising agent; but the last is probably the case,
with a like destruction of the compound constituting the colouring matter.
It may, however, be supposed that sulphurous acid acts as an oxidiser, as
it appears to do when it decomposes sulphuretted hydrogen; or it may act
by simply altering the compound by inserting itself, a view receiving some
support from the fact that wool whitened by sulphuring may be restored to
nearly its previous colour by merely treating it with soap or alkalies.
The bleaching power of light depends on its actinic or chemical rays,
which, like chlorine, appear to act as an oxidising agent.
Chlorates, chromates, chromic acid, manganates, &c., have been proposed as
bleaching agents for textile filaments and fabrics, but without success or
practical advantage. Immersion in water more or less strongly impregnated
with sulphurous acid has, however, been successfully substituted for the
common sulphuring process, particularly for silk.
To avoid the injury of the goods by sparks, and by drops of water highly
saturated with sulphurous acid falling from the roof, Mr Thom has invented
a method of passing them rapidly through, or keeping them in constant
motion in the sulphuring chamber. His apparatus is constructed on the
principle of the washing-machine, the fumes of burning sulphur being used
instead of water.
M. Tessie du Motay has proposed a new method for bleaching. He takes about
equal parts of permanganate of soda and sulphate of magnesia, and
dissolves them in lukewarm water. The tissues, previously freed from
grease, are to be plunged into this bath until they are covered with a
brown coating. They are then to be placed in a bath of sulphuric acid at 4
per cent., and rinsed after the brown matter is removed. They may be
finally passed through sulphurous acid. Mr Ramsay's method consists in
sprinkling with water equal parts of chloride of lime and sulphate of
magnesia, when hydrochlorate of magnesia is formed. It may be remarked
that none of the more modern methods of bleaching have been found, when
reduced to practice, to be cheaper, better, or more advantageous to work
than those sanctioned by long experience and use.
[Further information in connection with bleaching will be found under the
heads ACTINISM, BLANCHING, CALICO-PRINTING, CHARCOAL, CHLORIDES
(Bleaching), CHROMATES, CHROMIC ACID, HYPOCHLORITES, HYPOCHLOROUS ACID,
LIGHT, RINSING, SPOTS and STAINS, SULPHURATION, WASHING, &c.; also under
BONES, ENGRAVINGS, FAT, FEATHERS, HORN, IVORY, OIL, PAPER, PRINTED BOOKS,
RAGS, SPONGE, STRAW-PLAIT, TALLOW, WAX, &c.[225]]
[Footnote 225: An accurate description of the apparatus and machinery
employed in bleach-works, with numerous engravings, will be found in Ure's
'Dict. of Arts, Manuf. & Mines,' 5th ed., i, 318-351, &c.]
=Bleaching Liq'uid.= Solution of chloride of lime.
=Bleaching Pow'der.= Chloride of lime.
=Bleaching Salts.= The commercial hypochlorites.
=BLEAR'-EYE= (bl[=e]re'-[=i]). _Syn._ LIPPITU'DO, L.; CHASSIE, LIPPITUDE,
Fr. An exudation of a puriform matter from the margins of the eyelids,
which are red, tumid, and painful; and frequently, during the night, glued
together by the discharge.
_Treatm._ Mild astringent collyria, as those of sulphate of zinc or alum
(6 or 8 gr. to 1 oz. of water). An ointment formed of 1 part of the
ointment of nitrate of mercury (Ph. L.), diluted with 11 parts of sweet
washed lard, may be advantageously applied nightly, by means of a
camel-hair pencil, the smallest quantity possible only being used. Excess
in eating and drinking should be avoided, and some aperient medicine
taken.
=BLEAK= (bl[=e]ke). _Syn._ BLAY[double-dagger], BLEY[double-dagger],
(bl[=a]). The _cypri'nus albur'nus_ (Linn.), a small river-fish, the
scales of which are used in making artificial pearls (which _see_).
=BLEB.= A vesicle or blister. In some states of general derangement of
health this arises spontaneously. It should be treated in the same way as
scalds.
=BLEED'ING= (bl[=e]de'-). In the sense of a flow or loss of blood, see
HÆMORRHAGE; in that of bloodletting, see CUPPING, LEECHING, VENESECTION,
&c.
=Bleeding Piles.= Take every morning aperient doses of milk of sulphur,
then a small teaspoonful of confection of black pepper every day. Wash
externally with a sponge and cold water. Apply compound gall. ointment to
the piles if external.
=Bleeding from the Air Passages and Lungs.= Let the patient at once go to
bed, and keep perfectly quiet, avoiding movement of any kind as much as
possible. Administer dilute acids in frequently repeated doses, with five
drops of tincture of digitalis. The bowels should be kept open by means of
Epsom salts in infusion of roses. Give iced drinks and let solid ice be
sucked. Mustard plasters may be applied to the chest. A morphia lozenge
may now and then be sucked gradually away, as well as a small piece of sal
prunella. The cough must be allayed by the administration of small doses
of morphia in gum water or barley water. All food should be taken cold.
The treatment that we have indicated in the last two forms of hæmorrhage
is intended for the exclusive guidance of emigrants or of others so placed
as to be unable to summon prompt medical aid. Wherever this can be
obtained no time should be lost in at once seeking it.
=Bleeding from the Nose.= Apply cold water containing ice, if obtainable.
It should be so applied to the nose as to cause a shock. A cold piece of
metal, such as a key, placed on the naked back sometimes stops the
hæmorrhage. If neither of the above means succeed inject with a syringe a
solution of alum or sulphate of zinc (ten grains to the ounce), or snuff
up the nostrils some gallic acid, powder of pomegranate, kino, or catechu,
mixed with starch. A plug of lint may also be dipped in either of the
above solutions, or rolled in the powders, and pushed up the nostrils, or
some tincture of perchloride of iron, properly diluted and applied on a
piece of lint, may be tried.
=Bleeding from the Stomach.= _Syn._ HEMATEMESIS. In this case the blood is
vomited usually in clots of a dark colour. It should be noticed whether it
comes from the back of the nose or throat. The treatment consists in
perfect repose in bed, and in the administration of dilute sulphuric acid
in infusion of roses, with saline aperients. If these fail to give relief,
tannin and krameria may be tried, and small doses of laudanum or five
grains of alum may be given every four hours. If in pain, add to it 1/4
grain of acetate of morphia. All food and drinks should be taken cold, the
latter iced. Pernitrate of iron in from 10 to 30 minim doses is a valuable
remedy.
=BLENDE= (bl[)e]nd). A name applied to several minerals; appr.,
zinc-blend, or native sulphuret of zinc--the black jack of miners.
=BLIGHT= (bl[=i]te). See MILDEW, and PLANTS (Diseases of).
=BLIND'NESS= (bl[=i]nd'-). _Syn._ ABLEP'SIA, CÆ'CITAS, &c., L.;
AVEUGLEMENT, CÉCITÉ, Fr.; BLINDHEIT, Ger. Deprivation or want of sight.
Blindness may be congenital, or born with a person; or it may arise from
accident, external violence, or disease. In the latter it may frequently
be relieved by medical and surgical treatment. See AMAUROSIS, CATARACT,
EYES, OPHTHALMIA, VISION, &c.
=Blindness, Day.= _Syn._ NIGHT'-SIGHT; N[)Y]CTALO'PIA, L. A disease of the
eye in which vision is painfully acute or more or less extinct in a strong
light, as that of day; but clear and pleasant in the dusk of evening and
at night. Its chief causes are excessive exposure of the eyes to the
direct influence of very strong or glaring light, or to heat, or both of
them together; and is often one of the sequelæ of ophthalmia (which
_see_).
=Blindness, Night.= _Syn._ DAY'-SIGHT; HEMERALO'PIA, L. An affection of
the eye, the reverse of the preceding, in which objects are clearly seen
only in broad daylight. In the beginning of the complaint the patient
continues to be able to see, though less clearly, for a short time after
sunset, and even by moonlight, and perhaps distinctly by bright candle
light; but after a short time this power is lost. It most frequently
occurs in hot climates, and low latitudes at sea. Its chief causes are
fatigue and exposure of the eyes to the glare of the tropical sun,
probably coupled with gastric derangement. In some cases it is congenital,
and is then generally incurable. The treatment consists in avoiding
exciting causes, and endeavouring to restore the tone of the stomach, and
the general health, by the usual methods. The eyes at the same time should
be topically medicated by the frequent use of cold water, or mild
astringent collyria. See OPHTHALMIA (Chronic).
=BLIS'TER.= _Syn._ PAP'ULA, PUS'TULA, L.; PUSTULE, VESSIE, &c., Fr.;
BLASE, BLATTER, Ger. A bladder or vesicle caused by the deposition of
serous fluid between the cuticle and the derma or true skin, occasioned by
the application of a vesicant, or by a burn, scald, or friction.
=Blister.= _Syn._ VESICATO''RIUM, L.; EPISPASTIQUE, VESICATOIRE, Fr.;
BLASEN-PFLASTER, B.-STOFF, Ger. A substance which vesicates or raises
blisters; in pop. lang., a vesicating plaster or similar application.
The use of blisters is very ancient, and appears to date back long prior
to the time of Hippocrates. Indeed, their value as cutaneous stimulants
and counter-irritants appears to have been recognised by the medical
faculty of all nations down to the present time. It is a principle
sufficiently established with regard to the living system, that where a
morbid action exists, it may often be removed by inducing an action of a
different kind, as a state of excitement or irritation, in the same or a
neighbouring part. In this way is explained the utility of blisters in
local inflammation and spasmodic action, and it is this principle which
regulates their application in pneumonia, gastritis, hepatitis, phrenitis,
angina, rheumatism, colic, spasmodic affections of the stomach,
&c.--diseases in which they are employed with the most marked advantage. A
similar principle exists with respect to pain; exciting one pain often
relieves another. Hence blisters frequently give relief in neuralgia,
toothache, and other like painful affections. Lastly, blisters, by their
operation, communicate a stimulus to the whole system, and raise the
vigour of the circulation. Hence, in part, their utility in fevers of the
typhoid kind, though in such cases they are used with still more advantage
to obviate or remove local inflammation.
Blisters are commonly prepared with cantharides plaster, or with some
other preparation of cantharides; and, in the former case, usually have
their surface sprinkled over with powdered Spanish fly; whilst the
blistering surface is surrounded with a margin spread with common adhesive
plaster, for the purpose of causing them to adhere to the part to which
they are applied. In order to prevent the action of the cantharides upon
the mucous membrane of the bladder, or urinary organs, they are also often
sprinkled with a little powdered camphor, or better still, are moistened
with camphorated ether, which, on its evaporation, leaves a thin layer of
camphor on the surface; but care must be taken that the layer be not too
thick, as in that case the plaster would not take effect. With a like
object, a piece of thin book-muslin or tissue-paper (silver-paper) is
frequently placed between the blistering surface of the plaster and the
skin; the efficacy of which may be still further heightened by first
soaking the muslin or paper in olive or almond oil.
The usual time an ordinary blister of cantharides plaster is allowed to
remain in contact with the skin is from 10 to 12 hours. It is then gently
removed. The subsequent treatment depends on the object in view. When it
is not wished to maintain a discharge from the blistered surface, the
vesicle is cut with the point of a pair of scissors at its most depending
part, to let out the fluid which it contains, followed by a dressing of
spermaceti or other simple ointment; but when the case requires the
blister to be kept open, or to be converted into a perpetual blister, as
it is sometimes called, the whole of the detached cuticle is carefully
removed with the scissors, and the part is dressed with either the
ointment of cantharides or of savine, at first more or less diluted with
lard or simple ointment, with an occasional dressing of resin cerate.
According to Mr Crowther, the blistered surface is best kept clean by
daily fomentation with warm water.
Of late years, to obviate the unpleasant effects occasionally arising from
the common blister, various compounds having cantharides for their base,
as well as fabrics spread with them, have been brought before the public.
These are noticed hereafter. See PLASTER, VESICANTS, &c.
=Blisters, Extempora''neous.= Among the best of these may be mentioned the
following:--
1. A piece of lint dipped in the strongest vinegar of cantharides, and
immediately after its application to the skin, covered over with a piece
of strapping, or preferably a piece of sheet gutta percha or oiled silk,
to prevent evaporation. Raises a blister in from 5 to 8 minutes.
2. Concentrated acetic acid, applied in the same way, has a similar
effect.
3. (Dr Darcq.) Into a flat watch glass pour from 8 to 10 drops of highly
concentrated liquor of ammonia; cover the liquid with a small piece of
linen of rather less diameter than that of the glass, and at once apply
this little apparatus to the previously shaved skin. The whole must be
kept in its place by means of moderate pressure with the fingers, until a
red ring, about 2 centimètres in breadth, is observed round the glass,
when it is certain that vesication is effected. Sometimes scarcely 30
seconds are necessary for obtaining the result. The apparatus may then be
removed, and the blistered part treated in the usual manner; the dressing
being according to the object in view.
4. (Trousseau.) Bibulous paper slightly wetted with a little of the
ethereal extract of cancharides, and instantly applied to the skin, the
whole being covered with a piece of common adhesive plaster to prevent
evaporation.
5. Boiling water applied by means of a suitably shaped tube, the adjacent
parts being at the same time protected from injury. Instantaneous.
=Blister, Horse.= See VETERINARY MEDICINES.
=Blister*, Perpet'ual.= See BLISTER (_antè_).
=BLIS'TERING.= _Syn._ VES'ICANS, VESICATO''RIUS, L.; EPISPASTIQUE,
VÉSICANT, VÉSICATOIRE, Fr.; BLASENZIEHEND, &c., Ger. In _medicine_, &c.,
that vesicates or raises blisters when applied to the skin.
=Blistering Pa'per, Plas'ter, Tis''sue= (t[)i]sh-[=u]), &c. See PLASTERS,
VESICANTS, &c.
=BLOAT'ER.= See BLOTE.
=BLONDE.= [Fr.] _Syn._ BLOND'-LACE. Silk-lace. The name is now also
applied to cotton-lace edged with silk. For the mode of cleaning it and
getting it up, see LACE and MUSLIN.
=BLOOD= (bl[)u]d). _Syn._ SAN''GUIS, L.; SANG, Fr.; BLUT, Ger. The general
circulating fluid of animals, and that on which the nourishment and growth
of their bodies depend, and from which all the secretions are formed. It
is warm and red in vertebrated animals; and, for the most part, cold and
white in the invertebrata. In man and all other mammals, and in birds--the
two highest classes of the animal kingdom--the blood, though collectively
forming but one circulating stream, varies considerably in appearance
according to the part or vessels in which it is found. That contained in
the left side of the heart, and in the arteries, possesses a very
brilliant scarlet colour, and is called arte''rial blood; whilst that
found in the right side of the heart, and in the veins, has a darkish
purple colour, and is called ve'nous blood. The two, however, differ
little from each other in their chemical properties and composition; the
most marked point of difference being that venous blood holds carbonic
acid in solution, whilst oxygen predominates in the blood of the arteries.
The fibrine of venous blood is also soluble in a solution of nitrate of
potassa; whilst that of arterial blood is insoluble in that menstruum.
_Comp._ Blood consists of a transparent and nearly colourless fluid
(plas'ma, se''rum, s[)e]ralbu'men), in which float about a countless
multitude of microscopic round red bodies (blood-discs, blood-corpuscles),
to which its colour is due, accompanied by a few colourless globules
(white blood-corpuscles) of a somewhat larger size. The red corpuscles are
found, on more minute examination, to consist of an envelope containing a
solution of hæmatosin.
_Prop._ These are, for the most part, well known. It has an alkaline
reaction, a saline and rather disagreeable sweetish taste, and when newly
drawn evolves a peculiar odour or halitus, which almost immediately
disappears. As it cools and on repose it coagulates, owing, according to
some, to the spontaneous solidification of the fibrine.
The following table, based upon the observations of Schmidt and the
analysis of Lehmann, is given by the latter, as representing the average
quantitative relation of the principal constituents of normal blood. It
will be noticed that the blood is here regarded as composed of two
portions, one consisting solely of the red particles, and the other of
the liquid, in which these red corpuscles are suspended, termed the
_liquor sanguinis_, which consists of the serum holding fibre in
solution:--
_Sp. gr. of Blood-corpuscles, 1·0885._