of potash soaps (soft soaps) with this oil have the property of yielding with water emulsions which do not settle for a long time and are found in the trade as “creolin,” “sapocarbol,” “lysol,” &c.
That description of creosote oil which is sold for the purpose of pickling railway sleepers, telegraph posts, timber for the erection of wharves and so forth, must satisfy special requirements which are laid down in the specifications for tenders to public bodies. These vary to a considerable extent. They always stipulate (1) a certain specific gravity (e.g. not below 1·035 and not above 1·065); (2) certain limits of boiling points (e.g. to yield at most 3% up to 150°, at most 30% between 150° and 255°, and at least 85% between 150° and 355°); (3) a certain percentage of phenols, as shown by extraction with caustic soda solution, say 8 to 10%.
Much of this creosote oil is obtained by mixing that which has resulted in the direct distillation of the tar with the liquid portion of the anthracene oils after separating the crude anthracene (see below). It is frequently stipulated that the oil should remain clear at the ordinary temperature, say 15° C., which means that no naphthalene should crystallize out.
Working up the Anthracene Oil Fraction.—The crude oil boils between 280° and 400° C. It is liquid at 60° C., but on cooling about 6 to 10% of crude anthracene separates as greenish-yellow, sandy crystals, containing about 30% of real anthracene, together with a large percentage of carbazol and phenanthrene. This crystallization takes about a week. The crude anthracene is separated from the mother oils by filter presses, followed by centrifugals or by hot hydraulic presses. The liquid oils are redistilled, in order to obtain more anthracene, and the last oils go back to the creosote oil, or are employed for softening the hard pitch (vide supra). The crude anthracene is brought up to 50 or 60, sometimes to 80%, by washing with solvent naphtha, or more efficiently with the higher boiling portion of the pyridine bases. The naphtha removes mostly only the phenanthrene, but the carbazol can be removed only by pyridine, or by subliming or distilling the anthracene over caustic potash. The whole of the anthracene is sold for the manufacture of artificial alizarine.
Bibliography.—The principal work on Coal-tar is G. Lunge’s Coal-tar and Ammonia (3rd ed., 1900). Consult also G. P. Sadtler, Handbook of Industrial Organic Chemistry (1891), and the article “Steinkohlentheer,” Kraemer and Spreker, in Encyklopädisches Handbuch der technischen Chemie (4th ed., 1905, viii. 1). (G. L.)
COALVILLE, a town in the Loughborough parliamentary
division of Leicestershire, England, 112 m. N.N.W. from London.
Pop. of urban district (1901) 15,281. It is served by the Midland
railway, and there is also a station (Coalville East) on the
Nuneaton-Loughborough branch of the London & North-Western
railway. This is a town of modern growth, a centre of
the coal-mining district of north Leicestershire. There are also
iron foundries and brick-works. A mile north of Coalville is
Whitwick, with remains of a castle of Norman date, while to
the north again are slight remains of the nunnery of Gracedieu,
founded in 1240, where, after its dissolution, Francis Beaumont,
the poet-colleague of John Fletcher, was born about 1586. In the
neighbourhood is the Trappist abbey of Mount St Bernard,
founded in 1835, possessing a large domain, with buildings
completed from the designs of A. W. Pugin in 1844.
COAST (from Lat. costa, a rib, side), the part of the land which
meets the sea in a line of more or less regular form. The word
is sometimes applied to the bank of a river or lake, and
sometimes to a region (cf. Gold Coast, Coromandel Coast)
which may include the hinterland. If the coast-line runs parallel
to a mountain range, such as the Andes, it has usually a more
regular form than when, as in the rias coast of west Brittany,
it crosses the crustal folds. Again, a recently elevated coast is
more regular than one that has been long exposed to wave action.
A recently depressed coast will show the irregularities that were
impressed upon the surface before submergence. Wave erosion
and the action of marine currents are the chief agents in coast
sculpture. A coast of homogeneous rock exposed to similar action
will present a regular outline, but if exposed to differential
action it will be embayed where that action is greatest. A coast
consisting of rocks of unequal hardness or of unequal structure
will present headlands, “stacks” and “needles” of hard rocks,
and bays of softer or more loosely aggregated rocks, when the
wave and current action is similar throughout. The southern
shore-line of the Isle of Wight and the western coast of Wales
are simple examples of this differential resistance. In time the
coast becomes “mature” and its outline undergoes little change
as it gradually recedes, for the hard rock being now more exposed
is worn away faster, but the softer rock more slowly because it is
protected in the bays and re-entrants.
COAST DEFENCE, a general term for the military and naval
protection and defence of a coast-line, harbours, dockyards,
coaling-stations, &c., against serious attack by a strong naval
force of the enemy, bombardment, torpedo boat or destroyer
raids, hostile landing parties, or invasion by a large or small
army. The principal means employed by the defender to cope
with these and other forms of attack which may be expected in
time of war or political crisis are described below. See also for
further details Navy; Army; Fortification and Siegecraft;
Ammunition; Ordnance; Submarine Mines; Torpedo.
The following is a general description of modern coast
defences as applied in the British service.
No system of coast defence is of any value which does not take full account of the general distribution of sea-power and the resultant strength of the possible hostile forces. By resultant strength is meant the balance of one side over the other, for it is now generally regarded as an axiom that two opposing fleets must make their main effort in seeking one another, and that the force available for attack on coast defences will be either composed of such ships as can be spared from the main engagement, or the remnant of the hostile fleet after it has been victorious in a general action.
Coast defences are thus the complement and to some extent the measure of naval strength. It is often assumed that this principle was neglected in the large scheme of fortification associated in England with the name of Lord Palmerston, but it is at least arguable that the engineers responsible for the details of this scheme were dependent then as now on the naval view of what was a suitable naval strength. Public opinion has since been educated to a better appreciation of the necessity for a strong navy, and, as the British navy has increased, the scale of coast defences required has necessarily waned. Such a change of opinion is always gradual, and it is difficult to name an exact date on which it may be said that modern coast defence, as practised by British engineers, first began.
An approximation may, however, be made by taking the bombardment of Alexandria (1881) as being the parting of the ways between the old and the modern school. At that time the British navy, and in fact all other navies, had not really emerged from the stage of the wooden battleships. Guns were still muzzle-loaders, arranged mainly in broadsides, and protected by heavy armour; sails were still used as means of propulsion; torpedoes, net defence, signalling, and search-lights quite undeveloped.
At this time coast defences bore a close resemblance to the ships—the guns were muzzle-loaders, arranged in long batteries like a broadside, often in two tiers. The improvement of rifled ordnance had called for increased protection, and this was found first by solid constructions of granite, and latterly by massive iron fronts. Examples of these remain in Garrison Fort, Sheerness, and in Hurst Castle at the west end of the Solent. The range of guns being then relatively short, it was necessary to place forts at fairly close intervals, and where the channels to be defended could not be spanned from the shore, massive structures with two or even three tiers of guns, placed as close as on board ship and behind heavy armour, were built up from the ocean bed. On both sides the calibre and weight of guns were increasing, till the enormous sizes of 80 and 100 tons were used both ashore and afloat.
The bombardment of Alexandria established two new principles, or new applications of old principles, by showing the value of concealment and dispersion in reducing the effect of the fire of the fleet. On the old system, two ships firing at one another or ships firing at an iron-fronted fort shot “mainly into the brown”; if they missed the gun aimed at, one to the right or left was likely to be hit; if they missed the water-line, the upper works were in danger. At Alexandria, however, the Egyptian guns were scattered over a long line of shore, and it was soon found that with the guns and gunners available, hits could only be obtained by running in to short range and dealing with one gun at a time.
This new principle was not at once recognized, for systems
