In France, blasphemy (which included, also, speaking against the Holy

Virgin and the saints, denying one's faith, or speaking with impiety of

holy things) was from very early times punished with great severity. The

punishment was death in various forms, burning alive, mutilation,

torture or corporal punishment. In the United States the common law of

England was largely followed, and in most of the states, also, statutes

were enacted against the offence, but, as in England, the law is

practically never put in force. In Germany, the punishment for

blasphemy is imprisonment varying from one day to three years, according

to the gravity of the offence. To constitute the offence, the blasphemy

must be uttered in public, be offensive in character, and have wounded

the religious susceptibilities of some other person. In Austria, whoever

commits blasphemy by speech or writing is liable to imprisonment for any

term from six months up to ten years, according to the seriousness of

the offence.

BLASS, FRIEDRICH (1843-1907), German classical scholar, was born on the

22nd of January 1843 at Osnabruck. After studying at Gottingen and Bonn

from 1860 to 1863, he lectured at several gymnasia and at the university

of Konigsberg. In 1876 he was appointed extraordinary professor of

classical philology at Kiel, and ordinary professor in 1881. In 1892 he

accepted a professorship at Halle, where he died on the 5th of March

1907. He frequently visited England, and was intimately acquainted with

leading British scholars. He received an honorary degree from Dublin

University in 1892, and his readiness to place the results of his

labours at the disposal of others, together with the courtesy and

kindliness of his disposition, won the respect of all who knew him.

Blass is chiefly known for his works in connexion with the study of

Greek oratory: _Die griechische Beredsamkeit von Alexander bis auf

Augustus_ (1865); _Die attische Beredsamkeit_ (1868-1880; 2nd ed.,

1887-1898), his greatest work; editions for the Teubner series of

Andocides (1880), Antiphon (1881), Hypereides (1881, 1894), Demosthenes

(Dindorf's ed., 1885), Isocrates (1886), Dinarchus (1888), Demosthenes

(Rehdantz' ed., 1893), Aeschines (1896), Lycurgus, _Leocrates_ (1902);

_Die Rhythmen der attischen Kunstprosa_ (1901); _Die Rhythmen der

asianischen und romischen Kunstprosa_ (1905). Among his other works are

editions of Eudoxus of Cnidus (1887), the [Greek: Athaenaion politeia]

(4th ed., 1903), a work of great importance, and Bacchylides (3rd. ed.,

1904); _Grammatik des neutestamentlichen Griechisch_ (1902; Eng. trans,

by H. St John Thackeray, 1905); _Hermeneutik und Kritik and

Palaographie, Buchwesen, und Handschriftenkunde_ (vol. i. of Muller's

_Handbuch der klassischen Altertumswissenschaft_, 1891); _Uber die

Aussprache des Griechischen_ (1888; Eng. trans, by W.J. Purton, 1890);

_Die Interpolationen in der Odyssee_ (1904); contributions to Collitz's

_Sammlung der griechischen Dialektinschriften_; editions of the texts of

certain portions of the New Testament (Gospels and _Acts_). His last

work was an edition of the _Choephori_ (1906).

See notices in the _Academy_, March 16, 1907 (J.P. Mahaffy);

_Classical Review_, May 1907 (J.E. Sandys), which contains also a

review of _Die Rhythmen der asianischen und romischen Kunstprosa_.

BLASTING, the process of rending or breaking apart a solid body, such as

rock, by exploding within it or in contact with it some explosive

substance. The explosion is accompanied by the sudden development of gas

at a high temperature and under a tension sufficiently great to overcome

the resistance of the enclosing body, which is thus shattered and

disintegrated. Before the introduction of explosives, rock was

laboriously excavated by hammer and chisel, or by the ancient process of

"fire-setting," i.e. building a fire against the rock, which, on

cooling, splits and flakes off. To hasten disintegration, water was

often applied to the heated rock, the loosened portion being afterwards

removed by pick or hammer and wedge. In modern times blasting has become

a necessity for the excavation of rock and other hard material, as in

open surface cuts, quarrying, tunnelling, shaft-sinking and mining

operations in general.

For blasting, a hole is generally drilled to receive the charge of

explosive. The depth and diameter of the hole and the quantity of

explosive used are all variable, depending on the character of the rock

and of the explosive, the shape of the mass to be blasted, the presence

or absence of cracks or fissures, and the position of the hole with

respect to the free surface of the rock. The shock of a blast produces

impulsive waves acting radially in all directions, the force being

greatest at the centre of explosion and varying inversely as the square

of the distance from the charge. This is evidenced by the observed

facts. Immediately surrounding the explosive, the rock is often finely

splintered and crushed. Beyond this is a zone in which it is completely

broken and displaced or projected, leaving an enveloping mass of more

or less ragged fractured rock only partially loosened. Lastly, the

diminishing waves produce vibrations which are transmitted to

considerable distances. Theoretically, if a charge of explosive be fired

in a solid material of perfectly homogeneous texture and at a proper

distance from the free surface, a conical mass will be blown out to the

full depth of the drill hole, leaving a funnel-shaped cavity. No rock,

however, is of uniform mineralogical and physical character, so that in

practice there is only a rough approximation to the conical crater, even

under the most favourable conditions. Generally, the shape of the mass

blasted out is extremely irregular, because of the variable texture of

the rock and the presence of cracks, fissures and cleavage planes. The

ultimate or resultant useful effect of the explosion of a confined

charge is in the direction where the least resistance is presented. In

the actual work of rock excavation it is only by trial, or by deductions

based on experience, that the behaviour of a given rock can be

determined and the quantity of explosive required properly proportioned.

Blasting, as usually carried on, comprises several operations: (1)

drilling holes in the rock to be blasted; (2) placing in the hole the

charge of explosive, with its fuze; (3) tamping the charge, i.e.

compacting it and filling the remainder of the hole with some suitable

material for preventing the charge from blowing out without breaking the

ground; (4) igniting or detonating the charge; (5) clearing away the

broken material. The holes for blasting are made either by hand, with

hammer and drill or jumper, or by machine drill, the latter being driven

by steam, compressed air, or electricity, or, in rare cases, by

hydraulic power. Drill holes ordinarily vary in diameter from 1 to 3

in., and in depth from a few inches up to 15 or 20 ft. or more. The

deeper holes are made only in surface excavation of rock, the shallower,

to a maximum depth of say 12 ft., being suitable for tunnelling and

mining operations.

_Hand Drilling_.--The work is either "single-hand" or "double-hand."

In single-hand drilling, the miner wields the hammer with one hand,

and with the other holds the drill or "bit," rotating it slightly

after every blow in order to keep the hole round and prevent the drill

from sticking fast; in double-hand work, one man strikes, while the

other holds and rotates the drill. For large and deep holes, two

hammermen are sometimes employed.

[Illustration: FIG. 1.]

[Illustration: FIG. 2.--Sledge-hammer.]

A miner's drill is a steel bar, occasionally round but generally of

octagonal cross-section, one end of which is forged out to a cutting

edge (fig. 1). The edge of the drill is made either straight, like

that of a chisel, or with a convex curve, the latter shape being best

for very hard rock. For hard rock the cutting edge should be rather

thicker and blunter, and therefore stronger, than for soft rock.

Drills are made of high-grade steel, as they must be tempered

accurately and uniformly. The diameter of drill steel for hand work is

usually from 3/4 to 1 in., and the length of cutting edge, or gauge,

of the drill is always greater than the diameter of the shank, in the

proportion of from 7.4 to 4.3. Holes over 10 or 12 in. deep generally

require the use of a set of drills of different lengths and depending

in number on the depth required. The shortest drill, for starting the

hole, has the widest cutting edge, the edges of the others being

successively narrower and graduated to follow each other properly, as

drill after drill is dulled in deepening the hole. Thus the hole

decreases in diameter as it is made deeper. The miner's hammer (fig.

2) ranges in weight from 3-1/2 to 4-1/2 lb. for single-hand drilling,

up to 8 or 10 lb. for double-hand. If the hole is directed downward, a

little water is poured into it at intervals, to keep the cutting edge

of the drill cool and make a thin mud of the cuttings. From time to

time the hole is cleaned out by the "scraper" or "spoon," a long

slender iron bar, forged in the shape of a hollow semi-cylinder, with

one end flattened and turned over at right angles. If the hole is

directed steeply upward and the rock is dry, the cuttings will run out

continuously during the drilling; otherwise the scraper is necessary,

or a small pipe with a plunger like a syringe is used for washing out

the cuttings. The "jumper" is a long steel bar, with cutting edges on

one or both ends, which is alternately raised and dropped in the hole

by one or two men. In rock work the jumper is rarely used except for

holes directed steeply downward, though for coal or soft shale or

slate it may be employed for drilling holes horizontally or upward.

Other tools used in connexion with rock-drilling are the pick and gad.

Holes drilled by hand usually vary in depth from say 18 to 36 in.,

according to the nature of the rock and purpose of the work, though

deeper holes are often made. For soft rock, single-hand drilling is

from 20 to 30% cheaper than double-hand, but this difference does not

hold good for the harder rocks. For these double-hand drilling is

preferable, and may even be essential, to secure a reasonable speed of

work.

[Illustration: Fig. 3.--Ingersoll-Sergeant Mining Drill.]

_Machine Drills._--The introduction of machine drills in the latter

part of the 19th century exerted an important influence on the work of

rock excavation in general, and specially on the art of mining. By

their use many great tunnels and other works involving rock excavation

under adverse conditions have been rapidly and successfully carried

out. Before the invention of machine drills such work progressed

slowly and with difficulty. Nearly all machine drills are of the

reciprocating or percussive type, in which the drill bit is firmly

clamped to the piston rod and delivers a rapid succession of strong

blows on the bottom of the hole. The ordinary compressed air drill

(which may, for surface work, be operated also by steam) may be taken

as an illustration. The piston works in a cylinder, provided with a

valve motion somewhat similar to that of a steam-engine, together with

an automatic device for producing the necessary rotation of the piston

and drill bit. While at work the machine is mounted on a heavy tripod

(fig. 3); or, if underground, sometimes on an iron column or bar,

firmly wedged in position between the roof and floor, or side walls,

of the tunnel or mine working. As the hole is deepened, the entire

drill head is gradually fed forward on its support by a screw feed, a

succession of longer and longer drill bits being used as required.

Among the numerous types and makes of percussion drill may be named

the following:--Adelaide, Climax, Darlington, Dubois-Francois,

Ferroux, Froelich, Hirnant, Ingersoll, Jeffrey, Leyner, McKiernan,

Rand, Schram, Sergeant, Sullivan and Wood.

[Illustration: Figs. 4 and 5.--Darlington's Rock Drill.]

One of the simplest of the machine drills is the Darlington (figs. 4

and 5): a is the cylinder; b, piston rod; c, bit; d, d, air inlets,

either being used according to the position of the drill while at

work; h, piston; j, rifle-bar for rotating piston and bit; k, ratchet

attached to j; l, brass nut, screwed into h, and in which j works; f,

chuck for holding drill-bit; n, air port communicating between ends of

cylinder, front and back of piston; o, exhaust port. This machine has

no valve. From its construction, the compressed air (or steam) is

always acting on the annular shoulder round the forward end of the

piston. The piston is thereby forced back on the in-stroke until the

port n is uncovered. This admits the compressed air to the rear end of

the cylinder, and as the area of this end of the piston is much

greater than that of the shoulder on the other end, the piston is

driven forward and strikes its blow. When it has advanced far enough

to cover the exhaust port o, the air behind the piston is exhausted,

and, under the constant inward pressure noted above, the stroke is

reversed. The rotation of piston and bit is caused by the rifle-bar j.

On the outward stroke, j, with its ratchet k, is free to turn under a

couple of pawls and springs, and consequently the piston delivers its

blow without rotation. On the inward stroke the ratchet is held fast

by the pawls, and the piston and bit are forced to rotate through a

small part of a revolution. The cylinder is fed forward with respect

to the shell r, by rotating the handle p, which works a long screw-bar

engaging with a nut on the under side of the cylinder. The shell r is

bolted to the clamp s, which in turn is mounted on the hollow column

or bar g, or on a tripod, according to the character of the work. By

means of the adjustable clamp s, the machine can be set for drilling a

hole in any desired direction. The drill makes from 400 to 800 strokes

per minute.

The "New Ingersoll" drill, which may be taken as an example of the

numerous machines in which valves are used, is shown in section in

fig. 6. The steam or compressed air is distributed through the ports

alternately to the ends of the cylinder, by the reciprocations of a

spool-valve working in a chest mounted on the cylinder. The movements

of this valve are caused by the strokes of the main piston, which, by

means of the wide annular groove around the middle of the piston,

alternately open and close the spool-valve exhaust ports. Fig. 3 shows

the Ingersoll "Light Mining drill," as mounted on a tripod, and in

position for drilling a hole vertically downward. In the Leyner drill

the drill-bit is not connected to the piston, but is struck a quick

succession of blows by the latter. An important feature of this

machine is the provision for directing a stream of water into the hole

for clearing out the cuttings. For this purpose the shank of the

drill-bit is perforated longitudinally, the water being supplied under

pressure from a small tank, to which compressed air is led.

A rock drill of entirely different design, the Brandt, has been

successfully used in Europe for driving railway tunnels. It is

operated by hydraulic power, the pressure water being supplied by a

pump. The hollow drill-bit, which has a serrated cutting edge, is

forced under heavy pressure against the bottom of the hole, and is

rotated slowly--at six to eight revolutions per minute--by a pair of

small hydraulic cylinders, thus grinding and crushing the rock instead

of chipping it. The bottom of the hole is kept clean and the drill-bit

cooled by a stream of water passing down through its hollow shank. On

account of its size and weight, this machine is not suitable for mine

work.

[Illustration: FIG. 6.--New Ingersoll Drill.]

Most of the machine drills are made in a number of sizes, from 2 in.

up to 5 in. diameter of cylinder, the larger sizes being capable of

drilling holes 5 in. diameter and 30 ft. deep. They range in weight

from say 95 to 690 lb. for the drill head (unmounted), the tripods

weighing from 40 to 260 lb., exclusive of the weights placed for

stability on the tripod legs (fig. 3). The sizes in most common use

for mining are from 2-1/2 in. to 3-1/8 in. diameter of cylinder. In

rock of average hardness the best drills make from 4 to 7.5 linear ft.

of hole per hour. For use in narrow veins, or other confined workings

underground, several extremely small and light compressed air drills

have been introduced, as, for example, the Franke and Wonder, the

first of which weighs complete only 16 lb., and the second 18 lb.

These drills are held in the hands of the miner in the required

position, and strike a rapid succession of light blows. A large number

of mechanical drills operated by hand power have been invented. Some

imitate hand-drilling in the mode of delivering the blow; in others

the drill-bit is caused to reciprocate by means of combinations of

crank and spring. None of these machines is entirely satisfactory, and

but few are in use.

Among percussion rock-drills operated by electricity are the Bladray,

Box, Durkee, Marvin and Siemens-Halske. The Marvin drill works with a

solenoid; most of the others have crank and spring movements for

producing the reciprocations of the piston. Power is furnished by a

small electric motor, either mounted on the machine itself, as with

the Box drill, or more often standing on the ground and transmitting

its power through a flexible shaft. Although rather frequently used,

electric percussion drills cannot yet be considered entirely

successful, at least for mine service, in competition with compressed

air machines. Another type of electric drill, however, has been

successfully used in collieries, viz. rotary auger drills, mounted on

light columns and driven through gearing by diminutive motors. These

are intended for boring in coal, slate or other similar soft material.

Hand augers resembling a carpenter's brace and bit are also often used

in collieries.

Whatever may be the method of drilling, after the hole has been

completed to the depth required, it is finally cleaned out by a

scraper or swab; or, when compressed air drills are used, by a jet of

air directed into the hole by a short piece of pipe connected through

a flexible hose with the compressed air supply pipe. The hole is then

ready for the charge.

[Illustration: FIG. 7.]

[Illustration: FIG. 8.]

_Location and Arrangement of Holes._--For hand drilling in mining the

position of the holes is determined largely by the character and shape

of the face of rock to be blasted. The miner observes the joints and

cracks of the rock, placing the holes to take advantage of them and so

obtain the best result from the blast. In driving a tunnel or drift,

as in figs. 7 and 8, the rock joints can be made of material

assistance by beginning with hole No. 1 and following in succession by

Nos. 2, 3 and 4. Frequently the ore, or vein matter, is separated from

the wall-rock by a thin, soft layer of clay (D, D, fig. 8). This would

act almost as a free face, and the first holes of the round would be

directed at an angle towards it, for blasting out a wedge; after which

the positions of the other holes would be chosen.

[Illustration: FIG. 9.]

[Illustration: FIG. 10.]

When machine drills are employed, less attention is given to natural

cracks or joints, chiefly because when the drill is once set up

several holes at different angles can be drilled in succession by

merely swinging the cylinder of the machine into a new position with

respect to its mounting. According to one method, the holes are placed

with some degree of symmetry, in roughly concentric rings, as shown by

figs. 9 and 10. The centre holes are blasted first, and are followed

by the others in one or more volleys as indicated by the dotted lines.

Another method is the "centre cut," in which the holes are drilled in

parallel rows on each side of the centre line of the tunnel, drift or

shaft. Those in the two rows nearest the middle are directed towards

each other, and enclose a prism of rock, which is first blasted put by

heavy charges, after which the rows of side holes will break with

relatively light charges.

_Explosives._--A great variety of explosives are in use for blasting

purposes. Up to 1864, gunpowder was the only available explosive, but

in that year Alfred Nobel first applied nitroglycerin for blasting,

and in 1867 invented dynamite. This name was originally applied to his

mixture of nitroglycerin with kieselguhr, but now includes also other

mechanical mixtures or chemical compounds which develop a high

explosive force as compared with gunpowder. Besides these there are

the so-called flameless or safety explosives, used in collieries where

inflammable gases are given off from the coal.

Gunpowder, or black powder, is seldom used for rock-blasting, except

in quarrying building-stone, where slow explosives of relatively low

power are desirable to avoid shattering the stone, and in such

collieries as do not require the use of safety explosives. Gunpowder

is exploded by deflagration, by means of a fuze, and exerts a

comparatively slow and rending force. The high explosives, on the

other hand, are exploded by detonation, through the agency of a fuze

and fulminating cap, exerting a quick, shattering, rather than a

rending force. Dynamites and flameless explosives are made in a

variety of strengths, and are packed in waterproofed cartridges of

different sizes. The grades of dynamite most commonly employed contain

from 35 to 60% of nitroglycerin; the stronger are used for tough rock

or deep holes, or for holes unfavourably placed in narrow mine

workings, as sometimes in shaft-sinking or tunnelling. When of good

quality high explosives are safer to handle than gunpowder, as they

cannot be ignited by sparks and are not so easily exploded. The

ordinary dynamites used in mining are about four times as powerful as

gunpowder.

Nitroglycerin in its liquid form is now rarely used for blasting,

partly because its full strength is not often necessary but chiefly

because of the difficulty and danger of transporting, handling and

charging it. If employed at all, it is charged in thin tinned plate

cases or rubber-cloth cartridges.

_Blasting with Black Powder._--The powder is coarse-grained, usually

from 1/8 to 3/16 in. in size, and is charged in paper cartridges, 8 to

10 in. long and of a proper diameter to fit loosely in the drill hole.

A piece of fuze, long enough to reach a little beyond the mouth of the

hole, is inserted in the cartridge and tied fast. For wet holes

paraffined paper is used, the miner waterproofing the joints with

grease. When more than one cartridge is required for the blast, that

which has the fuze attached is usually charged last. The cartridges

are carefully rammed down by a wooden tamping bar and the remainder of

the hole filled with tamping. This consists of finely broken rock, dry

clay or other comminuted material, carefully compacted by the tamping

bar on top of the charge. The fuze is a cord, having in the centre a

core of gunpowder, enclosed in several layers of linen or hemp

waterproofed covering. It is ignited by the miner's candle or lamp, or

by a candle end so placed at the mouth of the hole that the flame must

burn its way through the fuze covering. As the fuze burns slowly, at

the rate of 2 or 3 ft. per minute, the miner uses a sufficient length

to allow him to reach a place of safety.

For blasting in coal, "squibs" instead of fuzes are often used. A

squib is simply a tiny paper rocket, about 1/8 in. diameter by 3 in.

long, containing fine gunpowder and having a sulphur slow-match at one

end. It is fired into the charge through a channel in the tamping.

This channel may be formed by a piece of 1/4 in. gas pipe, tamped in

the hole and reaching the charge; or a "needle," a long taper iron

rod, is laid longitudinally in the hole, with its point entering the

charge, and after the tamping is finished, by carefully withdrawing

the needle a little channel is left, through which the squib is fired.

In this connexion it may be noted that for breaking ground in gassy

collieries several substitutes for explosives have been used to a

limited extent, e.g. plugs of dry wood driven tightly into a row of

drill holes, and which on being wetted swell and split the coal;

quicklime cartridges, which expand powerfully on the application of

water; simple wedges, driven by hammer into the drill holes; multiple

wedges, inserted in the holes and operated by hydraulic pressure from

a small hand force-pump.

_Blasting with High Explosives._--High explosives are fired either by

ordinary fuze and detonating cap or by electric fuze. Detonating caps

of ordinary strength contain 10 to 15 grains of fulminating mixture.

The cap is crimped tight on the end of the fuze, embedded in the

cartridge, and on being exploded by fire from the fuze detonates the

charge. The number of cartridges charged depends on the depth of hole,

the length of the line of least resistance, and the toughness and

other characteristics of the rock. Each cartridge should be solidly

tamped, and, to avoid waste spaces in the hole, which would reduce the

effect of the blast, it is customary to split the paper covering

lengthwise with a knife. This allows the dynamite to spread under the

pressure of the tamping bar. The cap is often placed in the cartridge

preceding the last one charged, but it is better to insert it last, in

a piece of cartridge called a "primer." Though the dynamites are not

exploded by sparks, they should nevertheless always be handled

carefully. It is not so essential to fill the hole completely and so

thoroughly to compact the tamping, as in charging black powder,

because of the greater rapidity and shattering force of the explosion

of dynamite; tamping, however, should never be omitted, as it

increases the efficiency of the blast. In exploding dynamite, strong

caps, containing say 15 grains of fulminating powder, produce the best

results. Weaker caps are not economical, as they do not produce

complete detonation of the dynamite. This is specially true if the

weather be cold. Dynamite then becomes less sensitive, and the

cartridges should be gently warmed before charging, to a temperature

of not more than 80 deg. F. Poisonous fumes are often produced by the

explosion of the nitroglycerin compounds. These are probably largely

due to incomplete detonation, by which part of the nitroglycerin is

vaporized or merely burned. This is most likely to occur when the

dynamite is chilled, or of poor quality, or when the cap is too weak.

There is generally but little inconvenience from the fumes, except in

confined underground workings, where ventilation is imperfect.

Like nitroglycerin, the common dynamites freeze at a temperature of

from 42 deg. to 46 deg. F. They are then comparatively safe, and so

far as possible should be transported in the frozen state. At very low

temperatures dynamite again becomes somewhat sensitive to shock. When

it is frozen at ordinary temperatures even the strongest detonating

caps fail to develop the full force. In thawing dynamite, care must be

exercised. The fact that a small quantity will often burn quietly has

led to the dangerously mistaken notion that mere heating will not

cause explosion. It is chiefly a question of temperature. If the

quantity ignited by flame be large enough to heat the entire mass to

the detonating point (say 360 deg. F.) before all is consumed, an

explosion will result. Furthermore, dynamite, when even moderately

heated, becomes extremely sensitive to shocks. There are several

accepted modes of thawing dynamite: (1) In a water bath, the

cartridges being placed in a vessel surrounded on the sides and bottom

by warm water contained in a larger enclosing vessel. The warm water

may be renewed from time to time, or the water bath placed over a

candle or small lamp, _not_ on a stove. (2) In two vessels, similar to

the above, with the space between them occupied by air, provided the

heat applied can be definitely limited, as by using a candle. (3) When

large quantities of dynamite are used a supply may be kept on shelves

in a wooden room or chamber, warmed by a stove, or by a coil of pipe

heated by exhaust steam from an engine. Live steam should not be used,

as the heat might become excessive. Thawing should always take place

slowly, never before an open fire or by direct contact with a stove or

steam pipes and care must be taken that the heat does not rise high

enough to cause sweating or exudation of liquid nitroglycerin from the

cartridges, which would be a source of danger.

For the storage of explosives at mines, &c., proper magazines must be

provided, situated in a safe place, not too near other buildings, and

preferably of light though fireproof construction. Masonry magazines,

though safer from some points of view, may be the cause of greater

damage in event of an explosion, because the brick or stones act as

projectiles. Isolated and abandoned mine workings, if dry, are

sometimes used as magazines.

[Illustration: FIG 11. Electrical Fuze.]

Firing blasts by electricity has a wide application for both surface

and underground work. An electrical fuze (fig. 11) consists of a pair

of fine, insulated copper wires, several feet long and about 1/40 of

an inch in diameter, with their bare ends inserted in a detonating

cap. For firing, the fuze wires are joined to long leading wires,

connected with some source of electric current. By joining the fuze

wires in series or in groups, any number of holes may be fired

simultaneously, according to the current available. A round of holes

fired in this way, as for driving tunnels, sinking shafts, or in large

surface excavations, produces better results, both in economy of

explosive and effect of the blast, than when the holes are fired

singly or in succession. Also, the miners are enabled to prepare for

the blast with more care and deliberation, and then to reach a place

of safety before the current is transmitted. Another advantage is that

there is no danger of a hole "hanging fire," which sometimes causes

accidents in using ordinary fuzes.

Hanging fire may be due to a cut, broken or damaged powder fuze, which

may smoulder for some time before communicating fire to the charge.

"Miss-fires," which also are of not infrequent occurrence with both

ordinary and electric fuzes, are cases where explosion from any cause

fails to take place. After waiting a sufficient length of time before

approaching the charged hole, the miner carefully removes the tamping

down to within a few inches of the explosives and inserts and fires

another cartridge, the concussion usually detonating the entire

charge. Sometimes another hole is drilled near the one which has

missed. No attempt to remove the old charge should ever be made.

High tension electricity, generated by a frictional machine, provided

with a condenser, was formerly much used for blasting. The bare ends

of the fuze wires in the detonating cap are placed say 1/8 in. apart,

leaving a gap across which a spark is discharged, passing through a

priming charge of some sensitive composition. The priming is not only

combustible but also a conductor of electricity, such as an intimate

mixture of potassium chlorate with copper sulphide and phosphide. By

the combustion of the priming the fulminate mixture in the cap is

detonated. As these fuzes are more apt to deteriorate when exposed to

dampness than fuzes for low-tension current, and the generating

machine is rather clumsy and fragile, low-tension current is more

generally employed. It may be generated by a small, portable dynamo,

operated by hand, or may be derived from a battery or from any

convenient electric circuit. The ends of the fuze wires in the

detonating cap are connected by a fine platinum filament (fig. 11),

embedded in a guncotton priming on top of the fulminating mixture, and

explosion results from the heat generated by the resistance opposed to

the passage of the current through the filament. Blasting machines are

made in several sizes, the smaller ones being capable of firing

simultaneously from ten to twenty holes. The fuzes must obviously be

of uniform electrical resistance, to ensure that all the connected

charges will explode simultaneously. The premature explosion of any

one of the fuzes would break the circuit.

In the actual operations of blasting, definite rules for the

proportioning of the charges are rarely observed, and although the

blasts made by a skilful miner seldom fail to do their work, it is a

common fault that too much, rather than too little, explosive is used.

The high explosives are specially liable to be wasted, probably

through lack of appreciation of their power as compared with that of

black powder. Among the indications of excessive charges are the

production of much finely broken rock or of crushed and splintered

rock around the bottom of the hole, and excessive displacement or

projection of the rock broken by the blast. In beginning any new piece

of work, such waste may be avoided or reduced by making trial shots

with different charges and depths of hole, and noting the results;

also by letting contracts under which the workmen pay for the

explosive. In surface rock excavation the location and determination

of the depth of the holes and the quantity of explosive used, are

occasionally put in charge of one or more skilled men, who direct the

work and are responsible for the results obtained.

Blasting in surface excavations and quarries is sometimes done on an

immense scale--called "mammoth blasting." Shafts are sunk, or tunnels

driven, in the mass of rock to be blasted, and, connected with them, a

number of chambers are excavated to receive the charges of explosive.

The preparation for such blasts may occupy months, and many tons of

gunpowder or dynamite are at times exploded simultaneously, breaking

or dislodging thousands, or even hundreds of thousands, of tons of

rock. This method is adopted for getting stone cheaply, as for

building macadamized roads, dams and breakwaters, obtaining limestone

for blast furnace flux, and occasionally in excavating large railway

cuttings. It is also applied in submarine blasting for the removal of

reefs obstructing navigation, and sometimes for loosening extensive

banks of partly cemented gold-bearing gravel, preparatory to washing

by hydraulic mining.

AUTHORITIES.--For further information on drilling and blasting

see:--Callon, _Lectures on Mining_ (1876), vol. i. chs. v. and vi.;

Foster, _Text-book of Ore and Stone Mining_, (1900), ch. iv.; Hughes,

_Text-book of Coal Mining_ (1901), ch. iii.; H.S. Drinker,

_Tunnelling, Explosive Compounds and Rock Drills_ (1878); M.C.

Ihlseng, _Manual of Mining_ (1905), pp. 596-696; Kohler, _Der

Bergbaukunde_ (1897), pp. 104-208; Daw, _The Blasting of Rock_ (1898);

Prelini, _Earth and Rock Excavation_ (1905), chs. v., vi. and vii.;

Gillette, _The Excavation of Rock_ (1904); Guttmann, _Blasting_

(1892); Spon's _Dictionary of Engineering_, art. "Boring and

Blasting"; Eissler, _Modern High Explosives_ (1893), pts. ii. and

iii.; Walke, _Lectures on Explosives_ (1897), chs. xix.-xxii. Also:

_Proc. Inst. Civ. Eng._ (London), vol. lxxxv. p. 264; _Trans. Inst.

Min. Eng._ (England), vols. xiv., xv. and xvi. (arts, by W. Maurice),

vol. xxvi. pp. 322, 348, vol. xxiv. p. 526 and vol. xxv. p. 108;

_Trans. Amer. Soc. Civ. Eng._, vol. xxvii. p. 530; _Trans. Amer. Inst.

Min. Eng._, vol. xviii. p. 370, vol. xxix p. 405 and vol. xxxiv. p.

871; _South Wales Inst. Eng._ (1888); _Jour. Ass. Eng. Socs._, vol.

vii. p. 58; _Jour. Chem. Met. and Mining Soc. of South Africa_, August

1905; _School of Mines Quarterly_, N.Y., vol. ix. p. 308; _Colliery

Guardian_, April 15, 1898, and February 6, 1903; _Mines and Minerals_,

February 1905, p. 348, January 1906, p. 259, and April 1906, p. 393;

_Eng. and Mining Jour._, April 19, 1902, p. 552; _The Engineer_,

February 24, 1905; _Elec. Rev._, June 9, 1899; _Eng. News_, vol.

xxxii. p. 249, and August 3, 1905; _Gluckauf_, September 28, 1901, and

July 5, 1902; _Osterr. Zeitschr. f. Berg- u. Huttenwesen_, May 18, 25,

1901, April 18, 1903 and November, 18, 1905; _Annales des mines_, vol.

xviii. pp. 217-248. (R. P.*)

BLAUBEUREN, a town of Germany, in the kingdom of Wurttemberg, 12 m. W.

of Ulm, with which it is connected by railway. Pop. (1900) 3114. It is

romantically situated in a wild and deep valley of the Swabian Alps at

an altitude of 1600 ft. and is partly surrounded by ancient walls. Of

the three churches (two Evangelical and one Roman Catholic) the most

remarkable is the abbey church (_Klosterkirche_), a late Gothic building

dating from 1465-1496, the choir of which contains beautiful 15th

century carved choir-stalls and a fine high altar with a triptych

(1496). The choir only is used for service (Protestant), the nave being

used as a gymnasium. The town church (_Stadtkirche_) also has a fine

altar with triptych. The Benedictine abbey, founded in 1095, was used

after the Reformation as a school, and is now an Evangelical theological

seminary. There are two hospitals in the town.

BLAVATSKY, HELENA PETROVNA (1831-1891), Russian theosophist, was born at

Ekaterinoslav, on the 31st of July (O.S.) 1831, the daughter of Colonel

Peter Hahn, a member of a Mecklenburg family, settled in Russia. She

married in her seventeenth year a man very much her senior, Nicephore

Blavatsky, a Russian official in Caucasia, from whom she was separated

after a few months; in later days, when seeking to invest herself with a

halo of virginity, she described the marriage as a nominal one. During

the next twenty years Mme Blavatsky appears to have travelled widely in

Canada, Texas, Mexico and India, with two attempts on Tibet. In one of

these she seems to have crossed the frontier alone in disguise, been

lost in the desert, and, after many adventures, been conducted back by a

party of horsemen. The years from 1848 to 1858 were alluded to

subsequently as "the veiled period" of her life, and she spoke vaguely

of a seven years' sojourn in "Little and Great Tibet," or preferably of

a "Himalayan retreat." In 1858 she revisited Russia, where she created a

sensation as a spiritualistic medium. About 1870 she acquired

prominence among the spiritualists of the United States, where she

lived for six years, becoming a naturalized citizen. Her leisure was

occupied with the study of occult and kabbalistic literature, to which

she soon added that of the sacred writings of India, through the medium

of translations. In 1875 she conceived the plan of combining the

spiritualistic "control" with the Buddhistic legends about Tibetan

sages. Henceforth she determined to exclude all control save that of two

Tibetan adepts or "mahatmas." The mahatmas exhibited their "astral

bodies" to her, "precipitated" messages which reached her from the

confines of Tibet in an instant of time, supplied her with sound

doctrine, and incited her to perform tricks for the conversion of

sceptics. At New York, on the 17th of November 1875, with the aid of

Colonel Henry S. Olcott, she founded the "Theosophical Society" with the

object of (1) forming a universal brotherhood of man, (2) studying and

making known the ancient religions, philosophies and sciences, (3)

investigating the laws of nature and developing the divine powers latent

in man. The Brahmanic and Buddhistic literature supplied the society

with its terminology, and its doctrines were a curious amalgam of

Egyptian, kabbalistic, occultist, Indian and modern spiritualistic ideas

and formulas. Mme Blavatsky's principal books were _Isis Unveiled_ (New

York, 1877), _The Secret Doctrine, the Synthesis of Science, Religion

and Philosophy_ (1888), _The Key to Theosophy_ (1891). The two first of

these are a mosaic of unacknowledged quotations from such books as

K.R.H. Mackenzie's _Royal Masonic Encyclopaedia_, C.W. King's

_Gnostics_, Zeller's _Plato_, the works on magic by Dunlop, E. Salverte,

Joseph Ennemoser, and Des Mousseaux, and the mystical writings of

Eliphas Levi (L.A. Constant). _A Glossary of Theosophical Terms_

(1890-1892) was compiled for the benefit of her disciples. But the

appearance of Home's _Lights and Shadows of Spiritualism_ (1877) had a

prejudicial effect upon the propaganda, and Heliona P. Blavatsky (as she

began to style herself) retired to India. Thence she contributed some

clever papers, "From the Caves and Jungles of Hindostan" (published

separately in English, London, 1892) to the _Russky Vyestnik_. Defeated

in her object of obtaining employment in the Russian secret service, she

resumed her efforts to gain converts to theosophy. For this purpose the

exhibition of "physical phenomena" was found necessary. Her jugglery was

cleverly conceived, but on three occasions was exposed in the most

conclusive manner. Nevertheless, her cleverness, volubility, energy and

will-power enabled her to maintain her ground, and when she died on the

8th of May 1891 (White Lotus Day), at the theosophical headquarters in

the Avenue Road, London, she was the acknowledged head of a community

numbering not far short of 100,000, with journalistic organs in London,

Paris, New York and Madras.

Much information respecting her will be found in V.S. Solovyov's

_Modern Priestess of Isis_, translated by Walter Leaf (1895), in

Arthur Lillie's _Madame Blavatsky and Her Theosophy_ (1895), and in

the report made to the Society for Psychical Research by the Cambridge

graduate despatched to investigate her doings in India. See also the

article THEOSOPHY.

BLAYDES, FREDERICK HENRY MARVELL (1818-1908), English classical scholar,

was born at Hampton Court Green, on the 29th of September 1818, being a

collateral descendant of Andrew Marvell, the satirist and friend of

Milton. He was educated at St Peter's school, York, and Christ Church,

Oxford. He was Hertford scholar in 1838, took a second class in literae

humaniores in 1840, and was subsequently elected to a studentship at

Christ Church. In 1842 he took orders, and from 1843 to 1886 was vicar

of Harringworth in Northamptonshire. During a long life he devoted

himself almost entirely to the study of the Greek dramatists. His

editions and philological papers are remarkable for bold conjectural

emendations of corrupt (and other) passages. His distinction was

recognized by his being made an honorary LL.D. of Dublin, Ph.D. of the

university of Buda Pest and a fellow of the royal society of letters at

Athens. He died at Southsea on the 7th of September 1908.

His works include:--Aristophanes: _Comedies and Fragments_, with

critical notes and commentary (1880-1893); _Clouds, Knights, Frogs,

Wasps_ (1873-1878); _Opera Omnia_, with critical notes (1886);

Sophocles; _Oedipus Coloneus, Oedipus Tyrannus_ and _Antigone_ (in

the Bibliotheca Classica, 1859); _Philoctetes_ (1870), _Trachiniae_

(1871), _Electra_ (1873), _Ajax_ (1875), _Antigone_ (1005); Aeschylus:

_Agamemnon_ (1898), _Choephori_ (1899), _Eumenides_ (1900),

_Adversaria Critica in Comicorum Graecorum Fragmenta_ (1890); _in

Tragicorum Graec. Frag._ (1894), _in Aeschylum_ (1895), _in Varios

Poetas Graecos et Latinos_ (1898), _in Aristophanem_ (1899), _in

Sophoclem_ (1899), _in Euripidem_ (1901), _in Herodotum_ (1901);

_Analecta Comica Graeca_ (1905); _Analecta Tragica Graeca_ (1906).

BLAYDON, an urban district in the Chester-le-Street parliamentary

division of Durham, England, on the Tyne, 4 m. W. of Newcastle by a

branch of the North-Eastern railway. Pop. (1881) 10,687; (1901) 19,617.

The chief industries are coal-mining, iron-founding, pipe, fire-brick,

chemical manure and bottle manufactures. In the vicinity is the

beautiful old mansion of Stella, and below it Stellaheugh, to which the

victorious Scottish army crossed from Newburn on the Northumberland bank

in 1640, after which they occupied Newcastle.

BLAYE-ET-STE LUCE, a town of south-western France, capital of an

arrondissement in the department of Gironde, on the right bank of the

Gironde (here over 2 m. wide), 35 m. N. of Bordeaux by rail. Pop. (1906)

of the town, 3423; of the commune, 4890. The town has a citadel built by

Vauban on a rock beside the river, and embracing in its enceinte ruins

of an old Gothic chateau. The latter contains the tomb of Caribert, king

of Toulouse, and son of Clotaire II. Blaye is also defended by the Fort

Pate on an island in the river and the Fort Medoc on its left bank, both

of the 17th century. The town is the seat of a sub-prefect, and has

tribunals of first instance and of commerce and a communal college. It

has a small river-port, and carries on trade in wine, brandy, grain,

fruit and timber. The industries include the building of small vessels,

distilling, flour-milling, and the manufacture of oil and candles. Fine

red wine is produced in the district.

In ancient times Blaye (_Blavia_) was a port of the Santones. Tradition

states that the hero Roland was buried in its basilica, which was on the

site of the citadel. It was early an important stronghold which played

an important part in the wars against the English and the Religious

Wars. The duchess of Berry was imprisoned in its fortress in 1832-1833.

BLAZE (A.-S. _blaese_, a torch), a fire or bright flame; more nearly

akin to the Ger. _blass_, pale or shining white, is the use of the word

for the white mark on the face of a horse or cow, and the American use

for a mark made on a tree by cutting off a piece of the bark. The word

"to blaze," in the sense of to noise abroad, comes from the A.-S.

_blaesan_, to blow, cf. the Ger. _blasen_; in sense, if not in origin,

it is confused with "blazon" in heraldry.

BLAZON, a heraldic shield, a coat of arms properly "described" according

to the rules of heraldry, hence a proper heraldic description of such a

coat. The O. Fr. _blason_ seems originally to have meant simply a shield

as a means of defence and not a shield-shaped surface for the display of

armorial bearings, but this is difficult to reconcile with the generally

accepted derivation from the Ger. _blasen_, to blow, proclaim, English

"blaze," to noise abroad, to declare. In the 16th century the heraldic

term, and "blaze" and "blazon" in the sense of proclaim, had much

influence on each other.

BLEACHING, the process of whitening or depriving objects of colour, an

operation incessantly in activity in nature by the influence of light,

air and moisture. The art of bleaching, of which we have here to treat,

consists in inducing the rapid operation of whitening agencies, and as

an industry it is mostly directed to cotton, linen, silk, wool and other

textile fibres, but it is also applied to the whitening of paper-pulp,

bees'-wax and some oils and other substances. The term bleaching is

derived from the A.-S. _blaecan_, to bleach, or to fade, from which also

comes the cognate German word _bleichen_, to whiten or render pale.

Bleachers, down to the end of the 18th century, were known in England as

"whitsters," a name obviously derived from the nature of their calling.

The operation of bleaching must from its very nature be of the same

antiquity as the work of washing textures of linen, cotton or other

vegetable fibres. Clothing repeatedly washed, and exposed in the open

air to dry, gradually assumes a whiter and whiter hue, and our ancestors

cannot have failed to notice and take advantage of this fact. Scarcely

anything is known with certainty of the art of bleaching as practised by

the nations of antiquity. Egypt in early ages was the great centre of

textile manufactures, and her white and coloured linens were in high

repute among contemporary nations. As a uniformly well-bleached basis is

necessary for the production of a satisfactory dye on cloth, it may be

assumed that the Egyptians were fairly proficient in bleaching, and that

still more so were the Phoenicians with their brilliant and famous

purple dyes. We learn, from Pliny, that different plants, and likewise

the ashes of plants, which no doubt contained alkali, were employed as

detergents. He mentions particularly the _Struthium_ as much used for

bleaching in Greece, a plant which has been identified by some with

_Gypsophila Struthium_. But as it does not appear from John Sibthorp's

_Flora Graeca_, edited by Sir James Smith, that this species is a native

of Greece, Dr Sibthorp's conjecture that the _Struthium_ of the ancients

was the _Saponaria officinalis_, a plant common in Greece, is certainly

more probable.

In modern times, down to the middle of the 18th century, the Dutch

possessed almost a monopoly of the bleaching trade although we find

mention of bleach-works at Southwark near London as early as the middle

of the 17th century. It was customary to send all the brown linen, then

largely manufactured in Scotland, to Holland to be bleached. It was sent

away in the month of March, and not returned till the end of October,

being thus out of the hands of the merchant more than half a year.

The Dutch mode of bleaching, which was mostly conducted in the

neighbourhood of Haarlem, was to steep the linen first in a waste lye,

and then for about a week in a potash lye poured over it boiling hot.

The cloth being taken out of this lye and washed, was next put into

wooden vessels containing buttermilk, in which it lay under a pressure

for five or six days. After this it was spread upon the grass, and kept

wet for several months, exposed to the sunshine of summer.

In 1728 James Adair from Belfast proposed to the Scottish Board of

Manufactures to establish a bleachfield in Galloway; this proposal the

board approved of, and in the same year resolved to devote L2000 as

premiums for the establishment of bleachfields throughout the country.

In 1732 a method of bleaching with kelp, introduced by R. Holden, also

from Ireland, was submitted to the board; and with their assistance

Holden established a bleachfield for prosecuting his process at

Pitkerro, near Dundee.

The bleaching process, as at that time performed, was very tedious,

occupying a complete summer. It consisted in steeping the cloth in

alkaline lyes for several days, washing it clean, and spreading it upon

the grass for some weeks. The steeping in alkaline lyes, called

_bucking_, and the bleaching on the grass, called _crofting_, were

repeated alternately for five or six times. The cloth was then steeped

for some days in sour milk, washed clean and crofted. These processes

were repeated, diminishing every time the strength of the alkaline lye,

till the linen had acquired the requisite whiteness.

For the first improvement in this tedious process, which was faithfully

copied from the Dutch bleachfields, manufacturers were indebted to Dr

Francis Home of Edinburgh, to whom the Board of Trustees paid L100 for

his experiments in bleaching. He proposed to substitute water acidulated

with sulphuric acid for the sour milk previously employed, a suggestion

made in consequence of the new mode of preparing sulphuric acid,

contrived some time before by Dr John Roebuck, which reduced the price

of that acid to less than one-third of what it had formerly been. When

this change was first adopted by the bleachers, there was the same

outcry against its corrosive effects as arose when chlorine was

substituted for crofting. A great advantage was found to result from the

use of sulphuric acid, which was that a souring with sulphuric acid

required at the longest only twenty-four hours, and often not more than

twelve; whereas, when sour milk was employed, six weeks, or even two

months, were requisite, according to the state of the weather. In

consequence of this improvement, the process of bleaching was shortened

from eight months to four, which enabled the merchant to dispose of his

goods so much the sooner, and consequently to trade with less capital.

No further modification of consequence was introduced in the art till

the year 1787, when a most important change was initiated by the use of

chlorine (q.v.), an element which had been discovered by C.W. Scheele in

Sweden about thirteen years before. The discovery that this gas

possesses the property of destroying vegetable colours, led Berthollet

to suspect that it might be introduced with advantage into the art of

bleaching, and that it would enable practical bleachers greatly to

shorten their processes. In a paper on chlorine or oxygenated muriatic

acid, read before the Academy of Sciences at Paris in April 1785, and

published in the _Journal de Physique_ for May of the same year (vol.

xxvi. p. 325), he mentions that he had tried the effect of the gas in

bleaching cloth, and found that it answered perfectly. This idea is

still further developed in a paper on the same substance, published in

the _Journal de Physique_ for 1786. In 1786 he exhibited the experiment

to James Watt, who, immediately upon his return to England, commenced a

practical examination of the subject, and was accordingly the person who

first introduced the new method of bleaching into Great Britain. We find

from Watt's own testimony that chlorine was practically employed in the

bleachfield of his father-in-law, Mr Macgregor, in the neighbourhood of

Glasgow, in March 1787. Shortly thereafter the method was introduced at

Aberdeen by Messrs Gordon, Barron & Co., on information received from De

Saussure through Professor Patrick Copland of Aberdeen. Thomas Henry of

Manchester was the first to bleach with chlorine in the Lancashire

district, and to his independent investigations several of the early

improvements in the application of the material were due.

In these early experiments, the bleacher had to make his own chlorine

and the goods were bleached either by exposing them in chambers to the

action of the gas or by steeping them in its aqueous solution. If we

consider the inconveniences which must have arisen in working with such

a pungent substance as free chlorine, with its detrimental effect on the

health of the work-people, it will be readily understood that the

process did not at first meet with any great amount of success. The

first important improvement was the introduction in 1792 of _eau de

Javel_, which was prepared at the Javel works near Paris by absorbing

chlorine in a solution of potash (1 part) in water (8 parts) until

effervescence began. The greatest impetus to the bleaching industry was,

however, given by the introduction in 1799 of chloride of lime, or

bleaching-powder, by Charles Tennant of Glasgow, whereby the bleacher

was supplied with a reagent in solid form which contained up to

one-third of its weight of available chlorine. Latterly frequent

attempts have been made to replace bleaching-powder by hypochlorite of

soda, which is prepared by the bleacher as required, by the electrolytic

decomposition of a solution of common salt in specially constructed

cells, but up to the present this mode of procedure has met with only a

limited success (see ALKALI MANUFACTURE).

_Bleaching of Cotton._

Cotton is bleached in the raw state, as yarn and in the piece. In the

raw state, and as yarn, the only impurities present are those which are

naturally contained in the fibres and which include cotton wax, fatty

acids, pectic substances, colouring matters, albuminoids and mineral

matter, amounting in all to some 5% of the weight of the material. Both

in the raw state and in the manufactured condition cotton also contains

small black particles which adhere firmly to the material and are

technically known as "motes." These consist of fragments of the cotton

seed husk, which cannot be completely removed by mechanical means. The

bleaching of cotton pieces is more complicated, since the bleacher is

called upon to remove the sizing materials with which the manufacturer

strengthens the warp before weaving (see below).

In principle, the bleaching of cotton is a comparatively simple process

in which three main operations are involved, viz. (1) boiling with an

alkali; (2) bleaching the organic colouring matters by means of a

hypochlorite or some other oxidizing agent; (3) souring, i.e. treating

with weak hydrochloric or sulphuric acid. For loose cotton and yarn

these three operations are sufficient, but for piece goods a larger

number of operations is usually necessary in order to obtain a

satisfactory result.

_Loose Cotton._--The bleaching of loose or raw cotton previous to

spinning is only carried out to a very limited extent, and consists

essentially in first steeping the material in a warm solution of soda

for some hours, after which it is washed and treated with a solution

of bleaching powder or sodium hypochlorite. It is then again washed,

soured with weak sulphuric or hydrochloric acid, and ultimately washed

free from acid. Careful treatment is necessary in order to avoid any

undue matting of the fibres, while any drastic treatment, such as

heating with caustic soda and soap, as used for other cotton

materials, cannot be employed, since the natural wax would thereby be

removed, and this would detract from the spinning qualities of the

fibre. In case the cotton is not intended to be spun, but is to serve

for cotton wool or for the manufacture of gun cotton, more drastic

treatment can be employed, and is, in fact, desirable. Thus, cotton

waste is first extracted with petroleum spirit or some other suitable

solvent, in order to remove any mineral oil or grease which may be

present. It is then boiled with dilute caustic soda and resin soap,

washed, bleached white with bleaching-powder, washed, soured and

finally washed free from acid. In these operations, a certain amount

of matting is unavoidable, and it is consequently necessary to open

out the material after drying, in scutchers.

_Cotton Yarn._--Cotton yarn is bleached in the form of cops, hanks or

warps. In principle the processes employed are the same in each case,

but the machinery necessarily differs. Most yarn is bleached in the

hank, and it will suffice to give an account of this process only. The

sequence of operations is the same as in the bleaching of cotton

waste, and these can be conducted for small lots in an ordinary

rectangular wooden vat as used in dyeing, in which the yarn is

suspended in the liquor from poles which rest with their ends on the

two longer sides of the vat. For bleaching yarn in bulk, however, this

mode of procedure would involve so much manual labour that the process

would become too expensive. It is, therefore, mainly with the object

of economy that machinery has been introduced, by means of which large

quantities can be dealt with at a time.

The first operation, viz. that of boiling in alkali, is carried out in

a "kier," a large, egg-ended, upright cylindrical vessel, constructed

of boiler-plate and capable of treating from one to three tons of yarn

at a time. In construction, the kiers used for yarn bleaching are

similar in construction to those used for pieces (see below). The yarn

to be bleached is evenly packed in the kier, and is then boiled by

means of steam with the alkaline lye (3-4% of soda ash or 2% caustic

soda on the weight of the cotton being usually employed) for periods

varying from six to twelve hours. It is essential that a thorough

circulation of the liquor should be maintained during the boiling, and

this is effected either by means of a steam injector, or in other

ways. As a rule low pressure kiers (working up to 10 lb. pressure) are

employed for yarn bleaching, though some bleachers prefer to use high

pressure kiers for the purpose.

When the boiling has continued for the requisite time (6-8 hours), the

steam is shut off, and the kier liquor blown off, when the yarn is

washed in the kier by filling the latter with water and then running

off, this operation being repeated two or three times. The hanks are

now transferred to a stone cistern provided with a false bottom, from

beneath which a pipe connects the cistern with a well situated below

the floor line. The well contains a solution of bleaching-powder,

usually of 2 deg. Tw. strength, and this is drawn up by means of a

centrifugal brass pump and showered over the top of the goods through

a perforated wooden tray, passing then by gravitation through the

goods back into the well. The circulation is maintained for one and a

half to two hours, when the yarn will be found to be white. The

bleaching-powder solution is now allowed to drain off, and water is

circulated through the cistern to wash out what bleaching powder

remains in the goods. The souring is next carried out either in the

same or in a separate cistern by circulating hydrochloric or sulphuric

acid of 2 deg. Tw. for about half an hour. This is also allowed to

drain, and the yarn is thoroughly washed to remove all acid, when it

is taken out and wrung or hydroextracted. At this stage the yarn may

be dyed in light or bright shades without further treatment, but if it

is to be sold as white yarn, it is blued. The blueing may either be

effected by dyeing or tinting with a colouring matter like Victoria

blue 4R or acid violet, or by treatment in wash stocks with a

suspension of ultramarine in weak soap until the colour is uniformly

distributed throughout the material. The yarn is now straightened out

and dried.

The bleaching of cotton yarn is a very straightforward process, and it

is very seldom that either complications or faults arise, providing

that reasonable care and supervision are exercised.

The _raison d'etre_ of the various operations is comparatively simple.

The effect of boiling with alkali is to remove the pectic acid, the

fatty acids, part of the cotton wax and the bulk of the colouring

matter, while the albuminoids are destroyed and the motes swelled up.

If soap be used along with the alkali, the whole of the wax is removed

by emulsification. In the operation of bleaching proper, the calcium

hypochlorite of the chloride of lime through coming into contact with

the carbonic acid of the atmosphere suffers decomposition according to

the equation, Ca(OCl)2 + CO2 + H2O -> CaCO3 + 2HOCl, and the

hypochlorous acid thus liberated destroys the colouring matter still

remaining from the first operation, by oxidation. At the same time the

motes which were swelled up by the alkali are broken up into small

fragments and are thus removed. In the operation of souring, the lime

which has been deposited on the fibres during the treatment with

bleaching powder is dissolved, while at the same time any other

metallic oxides (iron, copper, &c.) are removed.

_Cotton Pieces._--By far the largest bulk of cotton is bleached in the

piece, as it can be more conveniently and more economically dealt with

in this form than in any other. Though similar in principle to yarn

bleaching, the process of piece bleaching is somewhat more complex

because the pieces contain in addition to the natural impurities of

the cotton a considerable amount of foreign matter in the form of size

which has been incorporated with the warp before weaving, with the

object of strengthening it. This size consists essentially of starch

(farina), with additions of tallow, zinc chloride, and occasionally

other substances such as paraffin wax, magnesium chloride, soap, &c.,

all of which must be removed if a perfect bleach is to result.

Besides, mineral oil stains from the machinery of the weaving-shed are

of common occurrence in piece goods.

Cotton pieces are bleached either for whites, for prints or for dyed

goods. The processes employed for these different classes vary but

slightly and only in detail. The most drastic bleach is that required

for goods which are subsequently to be printed. For dyed goods, the

main object is not so much to obtain a perfect white as to remove any

impurities which might interfere with the dyeing, while avoiding the

formation of any oxycellulose. In bleaching for whites ("market

bleaching") it is essential that the white should be as perfect as

possible, and such goods are consequently invariably blued after

bleaching.

[Illustration: FIG. 1.--Section of a Dash-wheel.]

For small lots (1-20 pieces) the bleaching can be conducted on very

simple machinery. Thus many small piece dyers conduct the whole of

their bleaching on the jigger, a simple form of dyeing machine on

which most cotton piece goods are dyed (see DYEING). For muslins,

laces and other very light fabrics, which will not stand rough

handling, the operations are conducted mainly by hand, washing being

effected in the dash-wheel (fig. 1), which consists of a cylindrical

box, revolving on its axis. It has four divisions, as shown by the

dotted lines, and an opening into each division. A number of pieces

are put into each, abundance of water is admitted behind, and the

knocking of the pieces as they alternately dash from one side of the

division to the other during the revolution of the wheel effects the

washing. The process lasts from four to six minutes.

For velveteens, corduroys, heavy drills, pocketings and other fabrics

in which creasing has to be avoided as much as possible, the so-called

"open bleach" is resorted to, which differs from the ordinary process

chiefly in that the goods are treated throughout at full width.

The great bulk of cotton pieces is bleached in rope form, i.e.

stitched together end to end and laterally collapsed, so that they

will pass through a ring of 4 to 5 in. in diameter.

The first operation which the goods undergo on arriving in the

grey-room of the bleachworks is that of stamping with tar or some

other indelible material in order that they may be identified after

passing through the whole process. They are then stitched together end

to end by means of special sewing machines, the stitch being of such a

nature (chain stitch) that the thread can be ripped out at one pull at

the end of the operations.

_Singeing._--In the condition in which the pieces leave the loom and

come into the hands of the bleacher, the surface of the fabric is seen

to be covered with a _nap_ of projecting fibres which gives it a downy

appearance. For some classes of goods this is not a disadvantage, but

in the majority of cases, especially for prints where a clean surface

is essential, the nap is removed before bleaching. This is usually

effected by running the pieces at full width over a couple of arched

copper plates heated to a full red heat by direct fire. An arrangement

of the kind is shown in fig. 2, in which the singe-plates, a and b,

are mounted over the flues of a coal fire. The plate b is most highly

heated, a being at the end of the flue farthest removed from the

fire. The cloth enters over a rail A, and in passing over the plate a

is thoroughly dried and prepared for the singeing it receives when it

comes to the highly-heated plate b. A block d, carrying two rails in

the space between the plates, can be raised or lowered so as to

increase or lessen the pressure of the cloth against the plates, or,

if necessary, to lift it quite free of contact with them.

[Illustration: FIG. 2.--Section of Singe-stove.]

The pieces on leaving the singeing machine are passed either through a

water trough or through a steam box with the object of extinguishing

sparks, and are then plaited down. The speed at which the pieces

travel over the singe plates is necessarily considerable and varies

with different classes of material.[1]

In lieu of plates, a cast-iron cylinder is sometimes employed ("roller

singeing"), the heating being effected by causing the flame of the

fire to be drawn through the roller, which is carried on two small

rollers at each end and revolves slowly in the reverse direction to

that followed by the piece, thus exposing continuously a freshly

heated surface and avoiding uneven cooling.

For figured pieces which have an uneven surface, it is obvious that

plate or roller singeing would only affect the portions which project

most, leaving the rest untouched. For such goods, "gas singeing" is

employed, which consists in running the pieces over a non-luminous gas

flame, the breadth of which slightly exceeds that of the piece, or in

drawing the flame right through the piece.[2] The construction of an

ordinary gas singeing apparatus is seen in section in fig. 3. Coal gas

mixed with air is sent under pressure through pipe a into the burners

b, b, where the mixture burns with an intense heat. The cloth travels

in the direction of the arrows, and in passing over the small nap

rollers c comes into contact with the flame four times in succession

before leaving the machine.

[Illustration: FIG. 3.--Gas Singeing Apparatus.]

Gas singeing is also used for plain goods, and being cleaner and under

better control has largely replaced plate singeing.

At this stage the goods which have been browned on the surface by

singeing are ready for the bleaching operations. A great many

innovations have been introduced in recent years in the bleaching of

calico, but although it is generally admitted that in point of view of

time and economy many of these processes offer considerable

advantages, the old process, in which a lime boil precedes the other

operations, is still the one which is most largely employed by

bleachers in England. In this, the sequence of operations is the

following--

_Grey Washing._--This operation (which is sometimes omitted) simply

consists in running the pieces through an ordinary washing machine (as

shown in fig. 5) through water in order to wet them out. On leaving

the machine they are piled in a heap and left over night, when

fermentation sets in, which results in the starch being to a large

extent hydrolysed and rendered soluble in water.

_Lime Boil._--In this operation, which is also known as _bowking_

(Ger. _beuchen_), the pieces are first run through milk of lime

contained in an ordinary washing machine and of such a strength that

they take up about 4% of their weight of lime (CaO). They are then run

over winches and guided through smooth porcelain rings ("pot-eyes")

into the kier, where they are evenly packed by boys who enter the

vessel through the manhole at the top. It is of the greatest

importance that the goods should be evenly packed, for, if channels or

loosely-packed places are left, the liquor circulating through the

kier, when boiling is subsequently in progress, will follow the line

of least resistance, and the result is an uneven treatment. Of the

numerous forms of kier in use, the injector kier is the one most

generally adopted. This consists of an egg-ended cylindrical vessel

constructed of stout boiler plate and shown in sectional elevation in

fig. 4. The kier is from 10 to 12 ft. in height and from 6 to 7 ft. in

diameter, and stands on three iron legs riveted to the sides, but not

shown in the figure. The bottom exit pipe E is covered with a

shield-shaped false bottom of boiler plate, or (and this is more

usual) the whole bottom of the kier is covered with large rounded

stones from the river bed, the object in either case being simply to

provide space for the accumulation of liquor and to prevent the pipe E

being blocked. The cloth is evenly packed up to within about 3 to 4

ft. of the manholes M, when lime water is run in through the liquor

pipe until the level of the liquid reaches within about 2 ft. of the

top of the goods. The manholes are now closed, and steam is turned on

at the injector J by opening the valve v. The effect of this is to

suck the liquor through E, and to force it up through pipe P into the

top of the kier, where it dashes against the umbrella-shaped shield U

and is distributed over the pieces, through which it percolates, until

on arriving at E it is again carried to the top of the kier, a

continuous circulation being thus effected. As the circulation

proceeds, the steam condensing in the liquor rapidly heats the latter

to the boil, and as soon as, in the opinion of the foreman, all air

has been expelled, the blow-through tap is closed and the boiling is

continued for periods varying from six to twelve hours under 20-60 lb.

pressure. Steam is now turned off, and by opening the valve V the

liquor, which is of a dark-brown colour, is forced out by the pressure

of the steam it contains.

[Illustration: FIG 4.--High Pressure Blow-through Kier.]

The pieces are now run through a continuous washing machine, which is

provided with a plentiful supply of water. The machine, which is shown

in fig. 5, consists essentially of a wooden vat, over which there is a

pair of heavy wooden (sycamore) bowls or squeezers. The pieces enter

the machine at each end, as indicated by the arrows, and pass rapidly

through the bowls down to the bottom of the vat over a loose roller,

thence between the first pair of guide pegs through the bowls again,

and travel thus in a spiral direction until they arrive at the middle

of the machine, when they leave at the side opposite to that on which

they entered. The same type of machine is used for liming, chemicking,

and souring.

The next operation is the "grey sour," in which the goods are run

through a washing machine containing hydrochloric acid of 2 deg. Tw.

strength, with the object of dissolving out the lime which the goods

retain in considerable quantity after the lime boil. The goods are

then well washed, and are now boiled again in the ash bowking kier,

which is similar in construction to the lime kier, with soda ash (3%)

and a solution of rosin (1-1/2%) in caustic soda (1-1/4%) for eight to

ten hours. For white bleaching the rosin soap is omitted, soda ash

alone being employed.

[Illustration: FIG 5.--Roller Washing Machine.]

The pieces are now washed free from alkali and the bleaching proper or

"chemicking" follows. This operation may be effected in various ways,

but the most efficient is to run the goods in a washing machine

through bleaching powder solution at 1/2 deg.-1 deg. Tw., and allow

them to lie loosely piled over night, or in some cases for a longer

period. They are now washed, run through dilute sulphuric or

hydrochloric acid at 2 deg. Tw. ("white sour") and washed again.

Should the white not appear satisfactory at this stage (and this is

usually the case with very heavy or dense materials), they are boiled

again in soda ash, chemicked with bleaching powder at 1/8 deg. Tw. or

even weaker, soured and washed. It is of the utmost importance that

the final washing should be as thorough as possible, in order to

completely remove the acid, for if only small quantities of the latter

are left in the goods, they are liable to become tender in the

subsequent drying, through formation of hydrocellulose.

The modern processes of bleaching cotton pieces differ from the one

described above, chiefly in that the lime boil is entirely dispensed

with, its place being taken by a treatment in the kier with caustic

soda (or a mixture of caustic soda and soda ash) and resin soap. The

best known and probably the most widely practised of these processes

is one which was worked out by the late M. Horace Koechlin in

conjunction with Sir William Mather, and this differs from the old

process not only in the sequence of the operations but also in the

construction of the kier. This consists of a horizontal egg-ended

cylinder, and is shown in transverse and longitudinal sections in

figs. 6 and 7. One of the ends E constitutes a door which can be

raised or lowered by means of the power-driven chain C. The goods to

be bleached are packed in wagons W outside the kier, and when filled

these are pushed home into the kier, so that the pipes p fit with

their flanges on to the fixed pipes at the bottom of the kier. The

heating is effected by means of steam pipes at the lowest extremity of

the kier, while the circulation of the liquor is brought about by

means of the centrifugal pump P, which draws the liquor through the

pipes p from beneath the false bottoms of the wagons and showers it

over distributors D on to the goods. By this mode of working a

considerable economy is effected in point of time, as the kier can be

worked almost continuously; for as soon as one lot of goods has been

boiled, the wagons are run out and two freshly-packed wagons take

their place. The following is the sequence of operations:--The goods

are first steeped over night in dilute sulphuric acid, after which

they are washed and run through old kier liquor from a previous

operation. They are then packed evenly in the wagons which are pushed

into the kier, and, the door having been closed, they are boiled for

about eight hours at 7-15 lb. pressure with a liquor containing soda

ash, caustic soda, resin soap and a small quantity of sulphite of

soda. The rest of the operations (chemicking, souring and washing) are

the same as in the old process.

[Illustration: FIG. 6.--The Mather Kier, cross section.]

[Illustration: FIG. 7.--The Mather Kier, longitudinal section.]

A somewhat different principle is involved in the Thies-Herzig

process. In this the kier is vertical, and the circulation of the

liquor is effected by means of a centrifugal or other form of pump,

while the heating of the liquor is brought about outside the kier in a

separate vessel between the pump and the kier by means of indirect

steam. The sequence of operations is similar to that adopted in the

Mather-Koechlin process, differing chiefly from the latter in the

first operation, which consists in running the goods, after singeing,

through very dilute boiling sulphuric or hydrochloric acid, containing

in either case a small proportion of hydrofluoric acid, and then

running them through a steam box, the whole operation lasting from

twenty to sixty seconds.

Bleached by any of the above processes, the cloth is next passed over

a mechanical contrivance known as a "scutcher," which opens it out

from the rope form to its full breadth, and is then dried on a

continuous drying machine. Fig. 8 shows the appearance and

construction of an improved form of the horizontal drying machine,

which is in more common use for piece goods than the vertical form.

The machine consists essentially of a series of copper or tinned iron

cylinders, which are geared together so as to run at a uniform speed.

Steam at 10-15 lb. pressure is admitted through the journalled

bearings at one side of the machine, and the condensed water is forced

out continuously through the bearings at the other side. The pieces

pass in the direction of the arrow (fig. 9) over a scrimp rail or

expanding roller round the first cylinder, then in a zigzag direction

over all succeeding cylinders, and ultimately leave the machine dry,

being mechanically plaited down at the other end.

If the bleaching process has been properly conducted, the pieces

should not only show a uniform pure white colour, but their strength

should remain unimpaired. Careful experiments conducted by the late

Mr. Charles O'Neill showed in fact that carefully bleached cotton may

actually be stronger than in the unbleached condition, and this result

has since been corroborated by others. Excessive blueing, which is

frequently resorted to in order to cover the defects of imperfect

bleaching, can readily be detected by washing a sample of the material

in water, or, better still, in water containing a little ammonia, and

then comparing with the original. The formation of oxycellulose during

the bleaching process may either take place in boiling under pressure

with lime or caustic soda in consequence of the presence of air in the

kier, or through excessive action of bleaching powder, which may

either result from the latter not being properly dissolved or being

used too strong. Its detection may be effected by dyeing a sample of

the bleached cotton in a cold, very dilute solution of methylene blue

for about ten minutes, when any portions of the fabric in which the

cellulose has been converted into oxycellulose will assume a darker

colour than the rest. The depth of the colour is at the same time an

indication of the extent to which such conversion has taken place.

Most bleached cotton contains some oxycellulose, but as long as the

formation has not proceeded far enough to cause tendering, its

presence is of no importance in white goods. If, on the other hand,

the cotton has to be subsequently dyed with direct cotton colours (see

DYEING), the presence of oxycellulose may result in uneven dyeing.

Tendering of the pieces, due to insufficient washing after the final

souring operation, is a common defect in bleached goods. As a rule the

free acid can be detected by extracting the tendered material with

distilled water and adding to the extract a drop of methyl orange

solution, when the latter will turn pink if free acid be present.

Other defects which may occur in bleached goods are iron stains,

mineral oil stains, and defects due to the addition of paraffin wax in

the size.

_Bleaching of Linen._

The bleaching of linen is a much more complicated and tedious process

than the bleaching of cotton. This is due in part to the fact that in

linen the impurities amount to 20% or more of the weight of the fibre,

whereas in cotton they do not usually exceed 5%. Furthermore these

impurities, which include colouring matter, intracellular substances and

a peculiar wax known as "flax wax," are more difficult to attack than

those which are present in cotton, and the difficulty is still further

enhanced in the case of piece goods owing to their dense or impervious

character.

Till towards the end of the 18th century the bleaching of linen both in

the north of Ireland and in Scotland was accomplished by bowking in

cows' dung and souring with sour milk, the pieces being exposed to light

on the grass between these operations for prolonged periods.

Subsequently potash and later on soda was substituted for the cows'

dung, while sour milk was replaced by sulphuric acid. This "natural

bleach" is still in use in Holland, a higher price being paid for linen

bleached in this way than for the same material bleached with the aid of

bleaching powder. In the year 1744 Dr. James Ferguson of Belfast

received a premium of L300 from the Irish Linen Board for the

application of lime in the bleaching of linen. Notwithstanding this

reward, the use of lime in the bleaching of linen was for a long time

afterwards forbidden in Ireland under statutory penalties, and so late

as 1815 Mr Barklie, a respectable linen bleacher of Linen Vale, near

Keady, was "prosecuted for using lime in the whitening of linens in his

bleachyard."

[Illustration: FIG. 8.--Mather & Platt's Horizontal Drying Machine.]

The methods at present employed for the bleaching of linen are, except

in one or two unimportant particulars, the same as were used in the

middle of the 19th century. In principle they resemble those used in

cotton bleaching, but require to be frequently repeated, while an

additional operation, which is a relic of the old-fashioned process,

viz. that of "grassing" or "crofting," is still essential for the

production of the finest whites. Considerably more care has to be

exercised in linen bleaching than is the case with cotton, and the

process consequently necessitates a greater amount of manual labour. The

practical result of this is that whereas cotton pieces can be bleached

and finished in less than a week, linen pieces require at least six

weeks. Many attempts have naturally been made to shorten and cheapen the

process, but without success. The use of stronger reagents and more

drastic treatment, which would at first suggest itself, incurs the risk

of injury to the fibre, not so much in respect to actual tendering as to

the destruction of its characteristic gloss, while if too drastic a

treatment is employed at the beginning the colouring matter is liable to

become set in the fibre, and it is then almost impossible to remove it.

Among the many modern improvements which have been suggested, mention

may be made of the use of hypochlorite of soda in place of bleaching

powder, the use of oil in the first treatment in alkali (Cross &

Parkes), while de Keukelaere suggests the use of sodium sulphide for

this purpose. With the object of dispensing with the operation of

grassing, which besides necessitating much manual labour is subject to

the influences of the atmospheric conditions, Siemens & Halske of Berlin

have suggested exposure of the goods in a chamber to the action of

electrolytically prepared ozone. Jardin seeks to achieve the same object

by steeping the linen in dilute nitric acid.

Since the qualities of linen which are submitted to the bleacher vary

considerably, and the mode of treatment has to be varied accordingly, it

is not possible to give more than a bare outline of linen bleaching.

Linen is bleached in the yarn and in the piece. Whenever one of the

operations is repeated, the strength of the reagent is successively

diminished. In yarn-bleaching the sequence of the operations is about

as follows:--(1) Boil in kier with soda ash. (2) Reel in bleaching

powder. This operation, which is peculiar to linen bleaching, consists

in suspending the hanks from a square roller into bleaching powder

solution contained in a shallow stone trough. The roller revolves

slowly, so that the hanks, while passing continuously through the

bleaching powder, are for the greater part of the time being exposed

to the air. (3) Sour in sulphuric acid. (4) Scald in soda ash. (The

term "scalding" means boiling in a kier.) (5) Reel in bleaching

powder. (6) Sour in sulphuric acid. (7) Scald in soda ash. (8) Dip,

i.e. steep in bleaching powder. (9) Sour in sulphuric acid. (10) Scald

in soda ash. (11) Dip in bleaching powder. (12) Sour in sulphuric

acid. For a full white, two more operations are usually required, viz.

(13) scald in soda ash, and (14) dip in bleaching powder. Washing

intervenes between all these operations.

Pieces are not stamped as in the case of cotton, but thread-marked by

hand with cotton dyed Turkey red. They are then sewn together end to

end, and subjected to the following operations:--

Boil with lime in kier.

The pieces are now separated and made up into bundles (except in the

case of very light linens, which may pass through the whole of the

operations in rope form) and soured with sulphuric acid.

First lye boil with soda ash and caustic soda.

Second lye boil. For some classes of goods no less than six lye boils

may be required.

Grass between lye boils (according to their number).

Rub with rubbing boards. This is also a speciality in linen bleaching,

and consists of a mechanical treatment with soft soap, the object of

which is to remove black stains in the yarn.

Bleach with hypochlorite of soda.

Scald. The two latter treatments are repeated three to five times,

each series constituting a "turn." Grassing intervenes between each

turn, and in some instances the pieces are rubbed before the last soda

boil.

[Illustration: FIG. 9.--Diagram showing the Horizontal Drying Machine

threaded with Cloth.]

The pieces are next steeped in large vessels (kiers) in weak

hypochlorite of soda, and then in weak sulphuric acid, these

treatments being repeated several times.

Ultimately the goods are mill-washed, blued with smalt and dried.

_Bleaching of other Vegetable Textile Fabrics._

_Hemp_ may be bleached by a process similar to that used for linen, but

this is seldom done owing to the expense entailed. _China grass_ is

bleached like cotton. _Jute_ contains in its raw state a considerable

amount of colouring matter and intracellular substance. Since the

individual fibres are very short, the complete removal of the latter

would be attended by a disintegration of the material. Although it is

possible to bleach jute white, this is seldom if ever carried out on a

large scale owing to the great expense involved. A half-bleach on jute

is obtained by steeping the goods alternately in bleaching powder (or

hypochlorite of soda) and sulphuric acid, washing intervening. For a

cream these treatments are repeated.

_Bleaching of Straw._

In the Luton district, straw is bleached principally in the form of

plait, in which form it is imported. The bleaching is effected by

steeping the straw for periods varying from twelve hours to several days

in fairly strong alkaline peroxide of hydrogen. The number of baths

depends upon the quality of straw and the degree of whiteness required.

Good whites are thus obtained, and no further process would be necessary

if the hats had not subsequently to be "blocked" or pressed at a high

temperature which brings about a deterioration of the colour. After

bleaching with peroxide and drying, the straw consequently undergoes a

further process of sulphuring, i.e. exposure to gaseous sulphurous acid.

Panama hats are bleached after making up, but in this case only peroxide

of hydrogen is used and a very lengthy treatment entailing sometimes

fourteen days' steeping is required.

_Bleaching of Wool._

In the condition in which it is delivered to the manufacturers wool is

generally a very impure article, even if it has been washed on the

sheep's back before shearing. The impurities which it contains consist

in the main of the natural grease (in reality a kind of wax) exuded from

the skin of the sheep and technically known as the "yolk," the dried-up

perspiration from the body of the sheep; technically called "suint," and

dust, dirt, burrs, &c., which mechanically adhere to the sticky surfaces

of the fibres. In this condition wool is quite unfit for any

manufacturing purposes and must be cleansed before any mechanical

operations can be commenced. Formerly the washing was effected in stale

urine, which owed its detergent properties mainly to the presence of

ammonium carbonate. The stale urine or _lant_ was diluted with four to

five times its bulk of water, and in this liquor, heated to 40 deg.-50

deg. C., the washing was effected.

At the present day this method has been entirely abandoned, the washing

or "scouring" being effected with soap, assisted by ammonia, potash,

soda or silicate of soda. The finest qualities of wool are washed with

soft soap and potash, while for inferior qualities, cheaper detergents

are employed. The operation is in principle perfectly simple, the wool

being submerged in the warm soap solution, where it is moved about with

forks and then taken out and allowed to drain. A second treatment in

weaker soap serves to complete the process. In dealing with large

quantities, wool-washing machines are employed, which consist

essentially of long cast-iron troughs which contain the soap solution.

The wool to be washed is fed in at one end of the machine and is slowly

propelled to the other end by means of a system of mechanically-driven

forks or rakes. As it passes from the machine, it is squeezed through a

pair of rollers. Three such machines are usually required for efficient

washing, the first containing the strongest and the third the weakest

soap.

The washing of wool is in the main a mechanical process, in which the

water dissolves out the suint while the soap emulsifies the yolk and

thus removes it from the fibre. The attendant earthy impurities pass

mechanically into the surrounding liquid and are swilled away.

In some works the wool is washed first with water alone, the aqueous

extract thus obtained being evaporated to dryness and the residue

calcined. A very good quality of potash is thus obtained as a

by-product. In many works in Yorkshire and elsewhere, the dirty soap

liquors obtained in wool-washing are not allowed to run to waste, but

are run into tanks and there treated with sulphuric acid. The effect of

this treatment is to decompose the soap, and the fatty acids along with

the wool-grease rise as a magma to the surface. The purified product is

known in the trade as "Yorkshire grease."

Attempts have been made from time to time to extract the natural grease

from wool by means of organic solvents, such as carbon bisulphide,

carbon tetrachloride, petroleum spirit, &c., but have not met with much

success.

Worsted yarn spun on the English system, as well as woollen yarn and

fabrics made from them, contain oil which has been incorporated with the

wool to facilitate the spinning. This oil must be got rid of previous to

bleaching, and this is effected by scouring in warm soap with or without

the assistance of alkalis.

The actual bleaching of wool may be effected in two ways, viz. by

treating the material either with sulphurous acid or with hydrogen

peroxide. Sulphurous acid may either be applied in the gaseous form or

in solution as bisulphite of soda. In working by the first method,

which is technically known as "stoving," the scoured yarn is wetted in

very weak soap containing a small amount of blue colouring matter,

wrung or hydro-extracted and then suspended in a chamber or stove.

Sulphur contained in a vessel on the floor of the chamber is now

lighted, and the door having been closed, is allowed to burn itself

out. The goods are left thus exposed to the sulphur dioxide overnight,

when they are taken out and washed in water. For piece goods a

somewhat different arrangement is employed, the pieces passing through

a slit into a chamber supplied with sulphur dioxide, then slowly up

and down over a large number of rollers and ultimately emerging again

at the same slit. Wool may also be bleached by steeping in a fairly

strong solution of bisulphite of soda and then washing well in water.

Wool bleached with sulphurous acid or bisulphite is readily affected

by alkalis, the natural yellow colour returning on washing with soap

or soda. A more permanent bleach is obtained by steeping the wool in

hydrogen peroxide (of 12 volumes strength), let down with about three

times its bulk of water and rendered slightly alkaline with ammonia or

silicate of soda. Black or brown wools cannot be bleached white, but

when treated with peroxide they assume a golden colour, a change which

is frequently desired in human hair.

_Bleaching of Silk._

In raw silk, the fibre proper is uniformly coated with a proteid

substance known as _silk-gum, silk-glue_ or _sericine_ which amounts to

19-25% of the weight of the material, and it is only after the removal

of this coating that the characteristic properties of the fibre become

apparent. This is effected by the process of "discharging" or

"boiling-off," which consists in suspending the hanks of raw silk over

poles or sticks in a vat containing a strong hot soap solution (30% of

soap on the weight of the silk). The liquor is kept just below boiling

point for two or three hours, the hanks being turned from time to time.

During the process, the sericine at first swells up considerably, the

fibres becoming slippery, but as the operation proceeds it passes into

solution. It is important that only soft water should be used for

boiling-off since calcareous impurities are liable to mar the lustre of

the silk.

The silk is now rinsed in weak soda solution and wrung. In this

condition it is suitable for being dyed, but if it is to be bleached,

the hanks are tied up loosely with smooth tape, put into coarse linen

bags to prevent the silk becoming entangled, and boiled again in soap

solution which is half as strong as that used in the first operation.

The hanks are now taken out, rinsed in a weak soda solution, washed in

water and wrung.

The actual bleaching of silk is usually effected by stoving as in the

case of wool, with this difference, that the operation is repeated

several times and blueing or tinting with other colours is effected

after bleaching. Silk may also be bleached with peroxide of hydrogen,

but this method is only used for certain qualities of spun silk and for

tussore.

_Ornamental feathers_ are best bleached by steeping in peroxide of

hydrogen, rendered slightly alkaline by the addition of ammonia. The

same treatment is applied to the bleaching of _ivory_. If peroxide of

hydrogen could be prepared at a moderate cost, it would doubtless find

a much more extensive application in bleaching, since it combines

efficiency with safety, and gives good results with both vegetable and

animal substances. (E. K.)