localities. The main building was of stone, brick, and glass, much more costly than the Hyde Park building, and intended to be more permanent; it was, however, only 800 feet long by 350 wide. Although the block of buildings was pierced by 400 windows, it was not so well suited as the glass palace in Hyde Park for the display of goods. When it was clearly seen that this building would be too small, two others were hastily erected; one, for machinery, was a gallery of immense length running along the north bank of the Seine; and the other, for a picture gallery, or Palais des Beaux Arts, was a wooden building in the Allée des Veuves. Altogether, the various buildings, together with the other expenses connected with the undertaking, involved the very large outlay of one million sterling; but Mr. Cole, one of the British commissioners, was informed, on good authority, that this sum was more than equalled by the extra expenditure of foreigners in Paris during those months. Owing partly to the substantial nature of the main building, and partly to difficulties between the government and the owners of the Palais de l'Industrie, the exhibition was not open till the 15th of May; it was closed on the 15th of November. The total number of visits paid was 4,533,464 (the Hyde Park number was about one-third more). About 40,000 British subjects were among the visitors. Unlike its English predecessor, the exhibition was open on Sundays as well as week days; Sunday was, indeed, the "peoples' day," on which the charge for admission was only 20 centimes (2d.); Friday was a special day, on which the charge varied from 2 to 5 francs (1s. 8d. to 48.), at different times during the autumn; on the other five days of the week the charge was uniformly 1 franc (10d.). On one particular Sunday (May 27th) the exhibition was thrown open gratuitously. There was only one kind of season ticket, charged at 50 francs (2.). Two sections of the exhibition,--the Palais de l'Industrie and the Palais des Beaux Arts-were distinct, and subject to separate charges for admission; the visitors to the former were four times as numerous as those to the latter. The articles were classified nearly in the same way as in London, there being in each case 30 classes altogether. To apportion medals to deserving exhibitors was the difficult labour of nearly 400 jurors, of whom about half were named by the French government, and the other half by foreign governments. The foreign jurors found this work to be a great tax on their time, seeing that they were thus engaged during the greater part of three summer months. There were four classes of medals distributed, and one grade of "honourable mention."

In relation to the British portion of this exhibition, it may be stated that the government placed the sum of 50,000l. at the disposal of the Board of Trade, to assist in defraying the expenses incurred by the exhibitors, and in preparing reports on the results of the exhibition. These reports have since been published by the government at a very cheap rate: they are about 30 in number, and were drawn up by some of the English jurors who had taken an active part in the onerous labour of examining the articles exhibited. The three portable volumes containing the reports constitute a valuable addition to the literature of the industrial arts.

Zollverein Exhibition at Munich.-The example set in 1851 has led to the organisation of many other industrial displays in the United Kingdom and on the Continent. We may name, as a few of these, a New Brunswick Exhibition in 1853; a Madras Exhibition of native industry in the same year; an Exhibition of German Industry at Munich in 1854; and an Art Exhibition at Edinburgh in 1857. From among these, it must suffice to give a few figures concerning the Munich Exhibition. An iron and glass building was constructed at a cost of 90,000l. It was 800 feet by 280, 87 feet high, and had 250,000 square feet of flooring. There were 6800 exhibitors, belonging to 33 Zollverein states, and the goods they sent, distributed into 12 classes (instead of 30 as in England and France), were roughly valued at 1,500,000l. The exhibition was open from the 15th of July to the 15th of October, at an admission fee varying from 44d. to 1s., English. The undertaking would probably have entailed a loss under any circumstances; but a visitation of cholera, in the last months of the autumn, so thinned the number of visitors, that the Bavarian government lost 200,000l. by the exhibition.

Manchester Art-Treasures Exhibition.-Although not exactly an international exhibiton, the Manchester Exhibition was so comprehensive in character, and so exceptional in its leading features, that it is fully entitled to a place here.

The Manchester Exhibition was the child of the French Exposition Universelle of 1855, as that was of the Great Exhibition of 1851: it differed from both in being an exhibition solely of artistic objects sent by their possessors, and not by producers or by dealers. The project was inaugurated at a meeting of Manchester gentlemen on the 26th day of March, 1856. The scheme was favourably received; an ample guarantee fund readily provided; the Queen and the Prince Consort gave their hearty support to the undertaking; and with few exceptions --and these in some cases forced ones, the effect of entails, &c.-the owners of works of art responded cheerfully and freely to the appeal. A building was erected at Old Trafford, about two miles from the centre of the city, and readily accessible by railway as well as omnibus, from a design by Mr. Salomons, in conjunction with Messrs. Young an i Co., of Edinburgh, the contractors. The exhibition was formally

opened by the Prince Consort on the 5th of May, 1857, and remained open till the 17th of October.

In its general plan the building was a parallelogram of 660 feet by 200 feet, with low projecting towers and attached corridors at the east or entrance end, and refreshment-rooms and offices built out from the sides. With the exception of the entrance front, which was of brick, the exterior of the building was constructed entirely of corrugated sheet-iron, affixed to a cast-iron framework; the interior being lined with wood. The entire structure covered an area of about 130,000 square feet, and cost somewhat over 30,000l. The interior consisted of a central hall and two side aisles, with transepts near the western end; at the western end a gallery extended round the transepts, and across the end of the building, and at the eastern end one was carried across the front. The central hall, which was 632 feet long and 104 feet wide, was divided into three sections by a series of slender coupled columns. The roof consisted of a semicircular span of 56 feet, springing from the columns, with hipped side spans 24 feet across. The side aisles, or picture galleries, were 432 feet long and 40 feet wide, and were spanned by a semicircular roof 50 feet high to the crown of the arch. A water-colour gallery at the western end of the building was 200 feet long by 24 feet wide.

The walls of the central hall were covered with portraits of celebrated English personages. Below these were cases filled with various articles of ornamental art, while along the body of the hall were ranges of upright cases containing larger, rarer, and more costly specimens of a similar kind. The general collection of modern sculpture was also arranged in a double series the entire length of the central hall. The Meyrick collection of armour, with choice examples from other repositories, and the entire Soulages collection of antique furniture, &c., occupied spaces near the western end of the hall. The South Aisle was devoted to Paintings by the Ancient Masters, the north to pictures by English painters. A room beyond the transept on the south side was occupied by the noble contribution of the Marquis of Hertford, and a miscellaneous collection of cabinet-paintings of the Dutch and Flemish schools. A corresponding saloon on the north side contained the Oriental Museum. Beyond these, extending across the western extremity of the building, was a long room which, with two smaller rooms, was entirely occupied by water-colour pictures. The western gallery was filled to overflowing with the collection of miniatures, drawings by ancient masters, engravings, etchings, woodcuts, lithographs, photographs, and architectural drawings. Pictures, mostly by modern masters of foreign schools, occupied the space afforded by the eastern gallery; and finally, along as much as was available of the wall of the corridor stretching towards the railway station, were hung paintings by the old masters, for which room could not be found in the south aisle.

The number of paintings of all kinds by ancient masters was 1115, by modern masters 689. Of British portraits there were 388; of miniatures and enamels there were 59 cases, but several of the cases contained numerous examples. The water-colour drawings numbered 969. Of modern sculpture there were 160 specimens, all being in marble except about a dozen which were in bronze. The original sketches and drawings by the old masters numbered 260; the engravings in line 937; in mezzotinto 161; the etchings 246; besides which there was a considerable number of woodcuts, and plain, tinted, and chromo-lithographs, and about 600 photographs. Finally, the museum of ornamental art comprised no fewer than 17,000 articles-some whose value was to be reckoned at hundreds of pounds each, others of marvellous beauty though of inferior pecuniary value, and others again whose only value lay in their rarity.

The paintings by the old masters, which formed the principal feature of the exhibition, were arranged as far as practicable in chronological order: the Italian pictures occupying the south wall, those of Germany and the Netherlands the north wall; the Spanish pictures being placed in the vestibules. For completeness and value such a collection was probably never before brought together, comprising as it did characteristic examples of almost every school, and extending over the entire range of the art from its dawn in the 13th to its decline in the 17th century. Of English paintings the collection, if less important was no less instructive. It was indeed the only attempt that had been made to exhibit a collection of English pictures which should suffice to give a tolerably complete view of the rise, progress, and present state of painting in England. And what was done in the south aisle for English oil painting was in the western rooms accomplished for English painting in water colours; the series showing in fact the whole history of the art by means of first-class examples. Of the British portrait gallery we have already spoken.

The collection of original drawings and sketches by the old masters contained 260 choice specimens by some of the chief artists of all countries; while of the collection of engravings it is enough to state, in the words of the catalogue, that "This was the first time in the history of the art of engraving at which an attempt was made to show the public generally, at one view, a complete chronological series of prints from the commencement of the art up to the present time," some of the examples being among the choicest of the most highlyprized prints of the greatest engravers of every country.

The Museum of Ornamental art-the most comprehensive and richest collection of the kind that probably was ever brought together,

persons by an injudicious employment of these agents, than in those of the lungs, from common colds to the more serious and fatal affections of these vital organs. The slight nature of many of the common maladies of the throat and lungs, and the fatality of consumption, which is generally though most erroneously regarded as an affection of the lungs themselves, while it is truly an affection of the whole constitution, have led to a degree of interference with the treatment of diseases of these organs not attempted in any other cases, as the multitude of popular remedies for coughs, colds, and consumptions attest. A certain exhalation from the internal surface of the lungs and airpassages constantly goes on in a state of health-any considerable diminution or augmentation of this secretion may require the assistance of medicines to raise it to the proper quantity in the one instance, or to evacuate the superfluity and repress the tendency to its excessive formation in the other. The chief causes which lead to diminished secretion are inflammation and spasm-hence at the commencement of inflammatory affections of the air-passages and of the lungs the inner membrane is dry, and by the stethoscope what is called the crepitating rale is heard; in asthma and hooping-cough, while the spasm lasts, there is an absence of secretion, which becomes abundant when the spasm yields.

To obviate these states very different means must be employed from what are necessary in the later stages of an inflammatory affection, or where there was extreme relaxation of the vessels of the lungs, and the exhaled fluid redundant in quantity. One of the terminations of inflammation being by effusion, when the increased action of the vessels has lasted for some time a state of the lungs occurs which is precisely the reverse of what it was before, and an extreme quantity of mucus obstructs the access of air to the blood circulating through the cells of the lungs : if this continue to accumulate, suffocation must follow. Too great an accumulation sometimes takes place, especially in elderly people, not from excessive secretion but from deficient absorption.

These are a few of the different states for which expectorants are used, but much circumspection is required to accommodate the means to the end. Where there is decided inflammation the best expectorants are those which lessen the inflammatory state, such as venesection and nauseating doses of tartrate of antimony or of ipecacuanha, and the inhalation of the vapour of warm water, simple or medicated, by means of Mudge's inhaler. But as the use of any such instrument requires considerable exertion of the respiratory organs, where the inflainmation is violent it is inadmissible, as the lungs must be kept in as tranquil a state as possible; but the head may be held over a basin of warm water, the vapour of which will be received by the lungs in the ordinary course of respiration.

When the inflammation has subsided, the more stimulating expectorants may be used. Where there is first spasm hindering secretion, and ultimately an excessive exhalation which must be cleared away, a combination of a sedative or antispasmodic medicine with the expectorant is best.

These are the principles which should regulate our choice in the more acute affections of the chest; but as no set of organs are so subject to chronic disorders as the lungs and their appendages, we frequently have recourse to expectorants to alleviate many of the symptoms attendant on them.

Lessening the tendency of blood towards the lungs, and directing it more towards the skin, is of service both in acute and chronic affections of the chest. Hence bathing the feet in water on the first feeling of an attack of cold, followed by antimonials or other diaphoretics, is of much utility, if the patient go into a warm bed immediately; while on the same principle, the use of flannel next the skin is the best preventive, and indispensable for all delicate persons, particularly if predisposed to diseases of the lungs. EXPLOSION is the sudden displacement of a considerable volume of air, or of any gaseous particles, accompanied by a loud report. In the well-known experiment with a glass cylinder having one end covered with a thin bladder tightly bound about it, the column of air incumbent on the bladder suddenly descends into the vessel on the rupture of the bladder when the air beneath is withdrawn by means of an air-pump; and the collision of its particles with one another or with the sides of the vessel produces the vibrations which cause the perception of sound. The particles of steam, in a state of high elasticity, when suddenly liberated by the bursting of the vessel in which they are contained, produce also a loud report by their collision with the atmospherical particles about them, or by the rush of air into the rarefied space which they have quitted. The elastic gases liberated on the application of fire to gunpowder in a tube, and the heat produced at the same time, create a rapid displacement of the particles of the surrounding atmosphere; and these as rapidly falling back into the vacuum within and about the fire-arm, cause a loud report by their collisions. A fulminating powder is the cause of a like explosion being produced, by means of the gases which are set free in consequence merely of the friction of the particles.

The explosions which, in the atmosphere, accompany a flash of lightning, are also ascribed to a similar displacement and subsequent rush of air into the vacuum produced.

For the explosion produced by chemical combinations, see DETO

NATION.

In the algeIf we were

EXPONENT; EXPONENTS, NOTATION OF. braical expression a, x is called the exponent of a. strictly to preserve the most ancient meaning of the term, z would be called the exponent of the whole symbol a*: but it is usual to call a the exponent of a, and the logarithm of a*.

From the time of Descartes it has been usual to employ exponents in abbreviation of repeated symbols of multiplication: but this was only the beginning of a series of extensions which have made the theory of exponents a fundamental part of analysis. Beginning with the simple substitution of a2 instead of a xa, a3 instead of a xa xa, and so on, we have a succession of new symbols suggested by the processes of algebra, namely, that a1 should stand for a, ao for unity, a* for the reciprocal of a*, and an for the nth root of the mth power of a. These conventions being made, the common algebraical theory of exponents is complete; and the student will find in works on algebra an account of the manner in which the necessity for these extensions appears. The theory of logarithms flows naturally from this notation and the binomial theorem.

Looking at the notation of exponents in another point of view, we see that a1, or a, signifying the performance of a certain operation on the unit, a2, or aa, signifies the repetition of the same operation upon a itself; a3 denotes the repetition of the same operation upon a2, and so on. Hence by analogy, whenever, in the higher parts of analysis, o signifies an operation performed upon r, 2 signifies the repetition of the operation upon pc. Thus if pc signify 1+ 2, then 2x is 1+2 (1+2x) or 3+4.r.

pc is 1+2 (3+4x) or 7+8.r, &c.

It appears by reasoning analogous to that which establishes the meaning of exponents in algebra, that a must stand for itself. Also - must signify the operation inverse to (or which destroys the effect of) pr; thus if pe signify x2, p' must be r. Also " x means that operation which performed n times in succession, gives the same result as or performed m times.

The Differential Calculus and the Calculus of Differences furnish striking examples of the notation of exponents. As soon as the student arrives at the higher parts of these subjects, he should pay particular attention to the structure of the notation, and in particular to the meaning of those theorems in which the symbols of operation are separated from those of quantity. EXPORTS. [IMPORTS and EXPORTS.]

EXTENT (Lat. extenta) is a writ of execution (sometimes called an extendi facias), which is directed to the sheriff against the body, lands, and goods, or the lands only, of a debtor; and it is also used as signifying the act of the sheriff or officer upon the writ itself.

The king by ancient prerogative is entitled to this writ, either in chief or in aid, for the purpose of obtaining satisfaction of debts originally due to him or assigned to the crown. The writ of extent in chief is an adverse proceeding by the king for the recovery of his own debt, and in which he is the real plaintiff. The writ is issued out of the Court of Exchequer; and the sheriff, for the purpose of executing it, may break open the defendant's doors, when purposely closed, either to arrest him or to take his goods. If, however, the defendant cannot be found, or is not meant to be arrested, the sheriff impanels a jury to inquire as to the debtor's lands and tenements, goods, and chattels; and after the inquisition is made, the lands then become bound to the crown until the debt is satisfied. The writ of extent in aid is also sued out at the instance and for the benefit of the crown against the debtor of a crown debtor: in this proceeding the king is the nominal plaintiff only. The writ is in effect an extent in the second degree, and in order to obtain it an extent pro formâ is sued out against the debtor to the crown, upon which an inquisition is taken; and if it be thereupon found that another person is indebted to him, the Court of Exchequer, on an affidavit to that effect, and also to the effect that the crown debt is in danger, will grant a fiat or warrant for an immediate extent in aid. Under this writ, the body of the defendant may in strictness be taken in execution as well as his lands, tenements, goods and chattels, &c.; but where there are effects sufficient to satisfy the debt, the court seems generally disposed to give the defendant his discharge. On the return of the writ of extent in chief or in aid to the court whence they are issued, an order is endorsed on the back of it," that if no one shall appear and claim the property of the goods, &c., mentioned in the inquisition, on or before that day se'nnight, a writ of venditioni exponas shall issue to sell the same." If the produce of the goods sold be not sufficient to pay the debt, the court will make an order for the sale of the debtor's lands under the 25th George III., c. 35.

There are various means of resisting the execution of the above writs, on the ground of informality or want of title in the crown; which may be referred to in the second volume of Mr. Tidd's work on the practice of the superior courts.

Upon the subject of extents for the subject see ELEGIT.

When lands are delivered over to a creditor upon an extent, a reasonable but not the real value is set upon them; and the effect is the same as if the creditor took a lease of the lands until his debt is satisfied. (Coke on Littleton; Tidd's Practice; Blackstone's Commentaries, Kerr's edition.)

EXTORTION. "Extortion," says Coke (Co. Litt., 368, b.), " is a great misprision, by wresting or unlawfully taking by any officer, by colour of his office, any money or valuable thing of or from any man, either that is not due, or more than is due, or before it is due." It is an offence at common law, punishable by fine and imprisonment at the discretion of the court. Also, money which has been obtained by extortion may be recovered in an action at law. There are various statutes providing penalties for extortion by sheriffs, under-sheriffs, bailiffs, gaolers, clerks of assize, &c.

EXTRACTION OF ROOTS. [INVOLUTION and EVOLUTION.] EXTRACTIVE MATTER. At a period when chemical analysis was less perfect than at present, the term extractive matter was applied to a heterogeneous mixture of matters obtained by treating vegetable substances with water, and then evaporating the solutions to dryness. Improvements in analysis have enabled the chemist to resolve such extractive matter into its constituents, and the term has now become nearly obsolete.

EXTRACTS are medicinal preparations of vegetable principles, obtained in various ways. Sometimes they are merely the juices expressed from the fresh plants, brought by careful evaporation to the consistence of honey, and then more properly denominated inspissated juices; at other times they consist of certain principles of the fresh or dried plant extracted by some menstruum in which they are soluble, such as water, proof spirit, vinegar, or ether, and afterwards evaporated, as in the former case. According to the nature of the menstruum employed the extract is called watery, alcoholic, acetous, or ethereal. The objects proposed in such proceedings are, to ensure the preservation of the active principles of the plant by removing the fluid in which they are dissolved, or the materials with which they are associated, that have a greater tendency to fermentation or putrefaction; to bring the valuable portion into the smallest possible compass; and to facilitate the administration of them by thus rendering them capable of being made into pills, &c.

The preparation of extracts requires the greatest care. The plants must be in every respect of the best quality, as regards the place of their growth, season when collected, &c., and the evaporation must be conducted rapidly, yet at a low temperature. Orfila found that the excellence of preparations of this kind was always in the reverse ratio of the temperature employed to form them. Mr. Barry effected a great improvement in the mode of preparing extracts by evaporating in vacuo. During the preparation, and especially towards the end of the operation, frequent stirring the contents of the evaporatingpan is necessary to prevent burning or decomposition of any portion Extracts may also be formed from dried plants, barks, roots, &c., by reducing them to fine powder and macerating it for 24 or 48 hours in sixteen times its weight of water. In general cold water is now employed, but in some cases it is proper to employ warın. The extract of cinchona, prepared with cold water, is less powerful than that prepared with warm.

of the mass.

Extracts are simple or compound, according as they are prepared from one plant or from several different kinds.

This mode of preparing vegetable principles is generally unsuitable where a volatile oil is the active agent, unless great care and a very low temperature be used.

A well-prepared extract should possess in a great degree the odour, and especially the taste, of the plant from which it is obtained; it should not have either an empyreumatic smell or taste, and it should have a proper and uniform consistence. It is necessary to preserve extracts in a dry situation: to assist in keeping watery extracts, it is customary to sprinkle a little alcohol over the surface before covering them up; but watery extracts, if made with cold water and due care, rarely require this precaution. It is proper to examine the condition of all extracts very frequently, both during very warm and very wet weather any portion which seems spoiled should be immediately thrown out.

Formerly, from the careless or unskilful mode of their preparation, extracts were the most uncertain and useless form of vegetable remedies; but since competent practical and scientific chemists have given their attention to the subject, they are now, in many instances, the most valuable contributions which chemistry has made to practical medicine. The term is also absurdly applied to a solution of diacetate of lead, called, after its discoverer, Goulard's Extract, or Extract of Saturn. This is only used externally.

EXTRAORDINARY RAY. When a pencil of light falls upon a doubly refracting crystal, such as one of Iceland spar, it is separated into two rays, one of which is refracted according to the ordinary law, and is termed the ordinary ray; the other, according to a new or extraordinary law, and is called the extraordinary ray. [POLARISATION OF LIGHT.]

EXTRAORDINARY REFRACTION. [MIRAGE.] EXTRAVASATION (extra, without, ras, a vessel), in medicine, signifies the escape of any of the fluids from its natural reservoir or canal into some neighbouring cavity or texture. The term is nearly synonymous with effusion, but less comprehensive, as it does not include the case of fluids poured out by secretion, such as dropsies, or any of the products of inflammation. It is most commonly employed in designating effusions of blood or of urine; and we shall therefore confine what we have to say on the subject to a brief notice of the principal

varieties of these accidents, referring the reader for more complete information to other parts of the work. Extravasations of blood are always serious, and often fatal, when the larger vessels and more important organs are concerned in them. Thus if blood escape in consequence of the rupture of an aneurism of the aorta into the bag which encloses the heart, the circulation is immediately arrested, and sudden death ensues. Such an accident is said to be "an extravasation of blood into or within the pericardium.” [ANEURISM.] Blood is sometimes driven with great force from a ruptured or wounded artery into the loose spongy substance consisting of connected cells which surrounds and separates the various organs, and is found in great abundance in every part of the body. This is called "extravasation of blood into the cellular tissue" of the part. In such cases, if the vessel be a large one, the extravasation may be so considerable as to occasion enormous swelling and distension of the contiguous parts; and it may be fatal from the amount of the hæmorrhage, or from pressure upon some vital organ, or from mortification. [HÆMORRHAGE.] This is a frequent source of danger in gunshot wounds. Fractures also are generally followed by considerable effusions of the same kind, which however are soon absorbed, and are not often attended with serious consequences, except in fractures of the skull; in that case they compress the brain, and produce the symptoms of apoplexy. [HEAD, INJURIES OF THE.] The thrombus, or swelling beneath the skin, so frequently observed after bleeding from the arm, is also formed by extravasation of blood into the cellular tissue. It arises from the puncture in the skin not corresponding with the opening in the vein, or not being sufficiently large. It soon disperses, and is of little importance. [BLEEDING.] Contusions are likewise followed by extravasation of blood into the cellular tissue under the skin, and in the skin itself, from the rupture of small vessels; and this is the reason of the dark colour assumed by the bruised parts, which often extends to a considerable distance from them, as in the familiar instance of a black eye. This superficial extravasation is generally called ecchymosis, a word of the same import.

Spontaneous extravasations of blood, allied to those last mentioned, frequently take place in the progress of various diseases, of which they may be causes or symptoms. The spots which appear under the skin and beneath the membranes which line the internal cavities and tubes, in plague, typhus fever, sea scurvy, and other complaints, are of the symptomatic kind; and these, as well as the discolorations after contusions, are included in the general term ecchymosis; they are also known by various other names, as vibices (wheals), petechia, and purpura. They are frequently attended with bleeding from the mucous membranes of the intestines and bladder, and of the nose; and they often occur, in the lower extremities especially, when the liver is enlarged, or otherwise diseased. They are supposed in general to indicate a want of tone in the system, and are attributed by some to a dissolved and semiputrescent condition of the blood; but they arise in some instances from a plethoric habit, and require bleeding for their cure.

One of the most common causes of apoplexy is an extravasation of blood in the substance of the brain, or between its membranes, from the simultaneous rupture of many minute arteries. It happens for the most part suddenly, when the vessels of the head are preternaturally distended, but yet not without some premonitory signs; and as the affection occurs most frequently at an advanced period of life, when the arterial system in general is disposed to disease, it is probable that the rupture is often preceded by some morbid change which renders the capillary vessels more than usually fragile. [APOPLEXY.] The termi apoplexy has been extended by modern pathologists to similar extravasations occurring in the texture of other organs besides the brain; it may take place in the liver when the venous system of the abdomen is loaded with blood, and from other causes; and it frequently happens in the lungs when their circulation is either obstructed or too forcibly urged in various diseases of the heart. [HEART, DISEASES OF THE.] It likewise happens very commonly in the early stage of consumption, when the body is yet full of blood, and the substance of the lungs is rendered brittle and inelastic by the deposit of tuberculous matter. [PHTHISIS.] When it occurs in the lungs, the injury is attended with haemoptysis, or spitting of blood. In this, as in many extravasations of the same kind, it is probable that the blood is effused rather in consequence of a rent, or breach of continuity in the structure concerned, than from what is implied in the common notion of the breaking of a blood-vessel. But in the early stage of consumption, the blood almost always escapes by exhalation from the extremities of the relaxed and distended vessels. See Louis' On Phthisis Pulmonalis.'

The presence of extravasated blood does not in itself produce much irritation, and the coagulum is soon absorbed when the quantity is not very great, and the vital powers are not depressed by concomitant causes. Where pressure is applicable, the absorption is much quickened by a bandage put on after the immediate effects of the injury have subsided, as in sprains and bruises of the limbs; friction and embrocations have the same effect. See An Essay on the Metamorphosis of the Coloured Blood Corpuscles in Extravasated Blood,' by John Burdon Sanderson, M.D., Edinb., 1851.

Extravasations of urine may take place in consequence of rupture of the bladder or urinary passages from ulceration, mechanical injuries, or any cause that produces distension to a great degree. If the fluid