the cost of linen fabrics; so that British yarns and cloths are now profitably exported to countries with which the manufacturers of Great Britain and Ireland were formerly unable to compete, and against which they were protected in the home market by high duties on importation.

Of the flax-spinning mills there is one at Leeds, belonging to Messrs. Marshall, which ranks among the largest factories in the world. One particular room is, we believe, the largest in existence devoted to manufacturing purposes; it covers two acres of ground, the roof is supported by fifty pillars, and lighted by sixty-six large conical skylights. The flax reaches the spinning-mills in small bundles of a few pounds

each. The fibres are first scutched out at the ends, by a machine which subjects them to a sort of combing action. They are then broken into three pieces each, the middle section being the best in quality. They are next heckled, or separated, straightened, and cleaned; this used formerly to be done with the heckle, a sort of large comb with iron teeth; but it is now effected by a rotating machine, on the periphery of which the flax is fixed, and drawn against or between a series of sharp teeth. The fibres pass through six heckling machines in succession, each having finer teeth than the one which preceded it. The heckled flax is then sorted into portions, according to fineness and other desired qualities. The next process, that of drawing, connects the short fibres of flax into one continuous sliver or riband, nearly in the

The spun yarn is applicable either for making thread or for weaving into linen goods. The quality of flax yarn is denoted by numbers describing the numbers of leas (a measure of 300 yards) contained in each pound weight. Thus a pound of No. 60 yarn measures 60 leas or 18,000 yards; No. 5 has only 1500 yards to the pound; while No. 200 has as much as 60,000 yards. Flax yarn is seldom spun of greater fineness than No. 200, which is fitted for making cambric of good quality. The improvements effected in the manufacture have greatly increased the average fineness and lowered the price. More flax is spun in Leeds than in any other town; but the weaving is carried on elsewhere. In and around Barnsley are woven linen, duck, check, drabbet, tick, huckaback, diaper, drill, towelling, and other kinds of flax goods. Dundee is famous for sailcloth, dowlas, sheeting, and other strong textile goods; and Aberdeen is taking up a position in the same department. Dunfermline and its vicinity produce finer fabrics, such as shirtings, damasks, and table-cloths. Belfast is the great

centre for good linen, and for the finer kinds of textile goods. Of these, duck is made in widths from three to five quarters of a yard; drill is a twilled linen, white or coloured, mostly used for summer trowsers; sheetings are known in the trade by the names of Irish, Russia, Imitation Russia, Lancashire, Yorkshire, Union Irish, and Union Lancashire, (the union cloth having a mixture of cotton with the flax); some of the sheetings are mostly or partly of hemp; damask is noticed under DAMASK; diaper is a figured fabric of lower quality; huckaback is a durable and economical kind of towelling. The best cambric is imported from France. Silesia is a sort of fine holland, used for window blinds. It may be stated here that many of the above-named fabrics are made either of flax or of hemp, according to the prices at which they are to be sold. The broad and well-made fabric for sailcloth is dressed with starch or flour before weaving, by the machine shown in the annexed cut; indeed most kinds of flaxen and hempen fabrics require some such dressing. The wet yarn, by passing over

dried.

and under two steam-heated metal boxes, becomes very quickly The statistics of this trade divide themselves into three parts, relating to the seed, the fibre, and the woven goods. About 4,000,000 bushels of linseed are imported annually; one-fifth for sowing into a flax-crop, and four-fifths for pressing linseed-oil. Three-fourths of the whole supply is from Russia; the sowing-seed is very carefully prepared, and is imported in casks officially branded; but the crushing-seed is coarser, and is imported either in bulk or in mat-bags. The flax imported in 1844 was about 1,600,000 cwts., in 1850 about 1,800,000 cwts., and in 1858 about 1,300,000 cwts.; the quantity varying considerably in different years. The price has varied still more widely, depending chiefly on the Russian crops. The computed value of the seed and fibre imported in 1858 was 2,700,000l. The woven linen goods, taking that term in its widest acceptation in reference to kind and quality, varied from 14d. to 21d. per yard on an average in the years for 1835 to 1853; in later years it has generally been near the lower of these two limits. In respect to woven goods, the bounties allowed on the shipment of linens were graduated according to their quality and value, and ranged from a halfpenny to a penny halfpenny per yard. In 1825 the rates were diminished one-tenth by an act then passed, and an equal proportion was to have been taken off in each subsequent year, so that the whole would have ceased in 1834; but by the act of 1828, when one-half the bounties had been removed, this course was modified by continuing for three years the rates of allowance payable in 1829, and thereafter repealing the bounty altogether; so that the payments ceased in 1832. Since then the export trade has rested on its own resources. In 1828 the declared value of the exports of these goods was 2,100,000l.; in 1837 it was 2,500,000l. In 1844 the exports (white or plain linen, printed and dyed flaxen goods, sailcloth, thread, and yarn) reached a value of 4,000,000l.; in 1850, 4,800,000l.; and in 1858, 5,900,0002. The quantities in the last-named year were, 120,000,000 yards of piece goods, and 35,000,000 lbs. of thread and yarn. The import of woven flaxen goods is very small. The export to France steadily increased until 1842, in which year the French government, influenced by a demand for protection, raised the import duty considerably; and the English trade in this commodity has suffered ever since. The flax and linen manufacturers of England are hoping for an extension of their dealings with France, consequent on the new treaty of commerce (1860). The number of mills and operatives engaged in this trade, in the United Kingdom, is noticed under FACTORIES.

LINES, in Music, are the five parallel lines forming, together with the intermediate spaces, the staff on which the notes and other characters are placed. [STAFF; LEGER.]

LINES OF INTRENCHMENT. In the article ENCAMPMENT it has been stated that armies in the field are not now, as formerly, surrounded by fortifications consisting of a continuous line of works;

and that, in general, a few breastworks or redoubts merely are constructed at intervals for the defence of the position. It will be sufficient, therefore, leaving out the consideration of those means of defence which are afforded by the natural obstacles of the country, as escarpments, rivers, marshes, &c., to describe briefly the nature of those intrenchments which were once, in all circumstances, considered indispensable, and which are still, to a certain extent, necessary when an army is to remain strictly on the defensive.

In the first place it may be said that a continuous breastwork would be advantageous for the protection of portions of a frontier, when the absence of natural obstacles might favour the enemy's marauding parties in making inroads for the purpose of levying contributions or laying waste the country; a parapet A B, broken by the redans c, C, from whence the defenders may annoy the enemy in flank on his

approach, termed a Redan Line, is the simplest form. The distances of the redans from one another may be about 150 yards, or not exceeding the range of musket shot: such was the construction recommended by Vauban, and since his time, it has been modified occasionally by giving to the curtains the form indicated by the lines a c, bc, in order that the ditch might be more effectually defended from the faces of the redans. All the faces should be so disposed that, if produced to an extent equal to the range of artillery, the lines of direction may fall on ground where the enemy could not establish batteries for the purpose of enfilading them; since, in the event of such enfilading taking place, the defenders would be compelled to abandon the parapets; artillery, if placed there, would be dismounted; the palisades in the ditch would be destroyed; and little resistance could be made, should the enemy subsequently assault the line. In general the redans may have the form of equilateral triangles, and the lengths of their sides may be about 50 yards. The entrances are usually in the middle of the curtains.

Instead of simple redans the advanced parts of the line have occasionally been formed of works resembling two united together, as D; which by the French engineers are called queues d'hyrondes, or double redans.

Again, when the nature of the ground does not permit the intrenchment to be formed with points so far advanced as the vertices of the redans c, c; when, for example, it is required to follow a bank of a river or one side of a road, it is proposed, in preference to a simple straight or curved line, to form the parapet with a series of branches in the positions indicated by a b, c d, &c., to P. A line of this kind is said to be à crémaillières: and in such situations a succession of fires from the branches a b, c d, &c., may be directed against the enemy

during his advance; on a level plain however the longer branches would be subject to the serious defect of being easily enfiladed. The Fig.2.

distances between the salient points b, d, &c., should not exceed 100 yards, and the lengths of the short branches may be about 18 or 20

M

yards. The re-entering angles a, e, &c., should contain about 100 degrees; and the entrances are usually placed at those points.

A like construction may be adopted when it is required to connect two points, as and N, by a line along a narrow and elevated ridge of ground; and in this case the directions of the branches bc, de, &c., may change in the middle of the line, as shown in the figure, in order that the fire from the long branches may be directed to the front of the nearest works, as м and N, in which it is to be supposed that artillery would be placed for the purpose of defending the ground before the intermediate line.

It may be added also, that the line à crémaillières (indented line) is convenient when it is required to join forts on hills or rising ground.

The most perfect fortification for defending a line of country presenting few natural obstacles to the advance of an enemy, should the importance of the position render it advisable to incur the labour of the construction, would be a series of bastions connected by curtains, either straight or broken. The principles on which the several fronts of fortification should be formed correspond to those adopted for regular fortresses, which are described in the article FORTIFICATION; the only difference being in the lengths of the several parts. These depend upon the whole length of the front, which here should not exceed 180 yards, that the ditches of the bastions may be well defended by common muskets from the collateral flanks. Neither ravelin nor covered-way would of course be necessary.

oppor

Lines of intrenchment composed of works placed at intervals from one another, provided the distances be not so great as to prevent the troops in them from mutually assisting each other, have great advantages over those formed of continuous lines of parapet. In the latter case it is scarcely possible for the army to make a movement for the purpose of attacking the enemy however favourable the tunity, since much time would be lost in issuing from the line through the narrow passages; and as these are the objects against which the fires from the enemy's batteries would then be incessantly directed, it would be almost impossible to form any extended front for attack; besides which, the enemy penetrating at any one point the whole line is turned. Detached works, on the other hand, constitute a number of strong points by which the position of the army is secured; while through the spacious intervals an advance or retreat may take place with the utmost facility. Their artillery is conveniently situated for putting the enemy's line in disorder previously to the attack, and for protecting the retiring columns in the event of their quitting the field. It may be added that detached works are capable of being easily adapted to any kind of ground; for it is merely necessary to place them on the more elevated spots in such situations that the enemy may not be able to penetrate between them without being exposed to their fire. On level ground the intrenchment may consist of a number of redans, as A, B, C, with or without flanks, disposed on a right line or curve, and at distances from one another equal to about 300 yards,

that the fire of musketry from them may defend the intervals. In the rear, and opposite the intervals between the works in the first line, a second line of works, as D, E, should be formed; and the faces of these should be disposed so as to flank the ditches and approaches to the others. The gorges of the exterior works should be open, as in the figure, or only protected by a line of palisades, which, in the event of the enemy gaining possession of those works, might be destroyed by the artillery in the second line.

Instead of a series of redoubts forming an interior line, it may suffice, should the works A, B, C, &c., be disposed on a convex arc, to have or large central redoubt as F, so situated as by its artillery to

defend both the intervals between the redans and the ground within their line. All the works which have been described consist of parapets formed of earth obtained by cutting a ditch in front; and the profile of any one work with its ditch is shown in the subjoined figure (4).

Fig. 4.

The elevation of the crest A above the natural ground is about 7 feet, unless the vicinity of a commanding height in front should render a greater relief necessary, and the depth of the ditch may be the same. The thickness a a of the upper part of the parapet is variable, and depends upon the importance of the work, or rather, upon the arm which may be employed in the attack: if it were required only to resist a fire of musketry, 3 feet would suffice; but from 8 feet to 12 feet would be necessary in the event of artillery being brought against it. (Twelve-pounder shot is the heaviest which the French have ever yet employed in the field.) The form of the parapet is the same as in permanent fortification; when time permits, the exterior and interior slopes should be revêted with sods, and a line of palisades should be planted along the foot of the counterscarp.

LININ, a crystalline substance of unknown composition found in the mountain flax (Linum catharticum). LINOLEIC ACID. [OLEIC ACID.]

LINOLEIN. [OLEIC ACID.]

LINSEED (Graine de Lin, French; Leinsaat, German; Lynzaad, Dutch; Linaza, Spanish; Linhaca, Portugal; Linseme, Italian; Semjalenjanve, Russian), the seed of the Lin, Linum, or flax plant, is a valuable product derived from the capsules of Linum usitatissimum, and consisting of small grayish-brown lenticular bodies, containing a mealy albumen, of so oleaginous a nature, that it yields by pressure in The seed of the flax-plant is great abundance the oil of linseed. harvested not merely with a view to the reproduction of the plant, but also because of the oil which it yields by compression. For both these purposes, of sowing and crushing, linseed is largely imported into the United Kingdom. [LINEN MANUFACTURE; FLAX.] It is largely used now as cattle food and the refuse, after its oil has been expressed, is the well-known oilcake of the cattle feeder. process which makes the oil clearer; or the bruised seeds are roasted LINSEED-OIL may be procured by cold expression of the seeds, a in the oil-mills, in which case it is brownish-yellow, and easily becomes rancid, probably from attracting oxygen. Linseed-oil is pellucid, with a faint but peculiar odour and taste, generally disagreeable, from being subrancid. Specific gravity 0.93. It easily dries: by reduction of temperature it merely becomes cloudy, but scarcely

freezes.

It may easily be purified by repeated agitation with water, by bleaching in the sun, or, better, by filtering it through newly prepared charcoal.

By long boiling it becomes dark-brown, tenacious, and thickened, but dries more easily, and in this state is used for printers' ink; by still longer boiling it becomes black, almost solid, and elastically tenacious, like caoutchouc, and in this state it serves for bird-lime.

By the addition of nitrous acid it becomes thick and red, then dark reddish brown, like tincture of iodine, but does not become solid. It is frequently adulterated with rape oil, which may be detected by this test. Neither does it form elaidin, as rape-oil does. But a simpler test is, that if wood be smeared with oil which has been adulterated, it does not become dry.

Linseed-oil is used to form liniments, of which the most common is that with lime-water, as an application to burns. But it is much more extensively used in the arts, particularly for painting. It is mildly laxative.

LINT. [LINUM USITATISSIMUM.]

LINUM USITATISSIMUM, Medical Properties of. The seeds of this plant yield several articles useful in medicine and surgery. The testa, or husk of the seeds, is very mucilaginous, the kernel contains much oil, and the farina or meal, procured by grinding or bruising the seeds, after the oil has been expressed, furnishes an excellent material for poultices, but now greatly superseded by Spongiopiline. [CATAPLASMS.] The seeds are oblong-ovate, acute, compressed, brown, shining, very smooth, the skin thin, the kernel white and oily. They are devoid of odour, but have an unpleasant mucilaginous oily taste. Old, rancid, and corroded seeds should be rejected. One part of seeds and two parts of water yield a strong mucilage. It is much better to

obtain the mucilage by merely pouring cold water on the entire seeds, than to bruise them and pour boiling water on them, as generally directed. The mucilage is analogous to that of the quince seed [CYDONIA in NAT. HIST. DIV.], and differs in its chemical habitudes, in several respects, from common gum. The compound infusion of linseed is demulcent, and the unpleasant taste may be much lessened by using cold water to form it, as stated above. The farina of the seeds, ground before the oil has been expressed, furnishes the best material for poultices, but does not keep well. The cake remaining after the expression of the oil is much used to fatten cattle, but gives a peculiar taste to the meat.

The lint, or charpie, used by surgeons to dress ulcers, &c., should always be prepared from linen-cloth and never from cotton, as an essential difference exists in the nature of their fibres, which causes that of cotton to prove extremely irritating.

LIP. [HARE LIP.]

LIPIC ACID. [SUCCINIC ACID.]

LIPRYL, a name formerly applied to the radical of glycerin. [GLY CERIN.]

LIQUEFACTION. When heat is supplied in sufficient quantity to a solid body, it changes its form and becomes liquid. When this change takes place in the case of ice the process is called liquefaction, but in the case of metals fusion. So also if heat be abstracted in sufficient quantity from a liquid, it usually becomes solid, which process, in the case of bodies which under ordinary circumstances are liquid, such as water, oil, &c., is called congelation; but for bodies which are usually solid, such as the metals, the process is called solidification. The more important phenomena attending liquefaction are stated under LATENT HEAT. [See also FREEZING MIXTURES; HEAT.] Bodies require very various amounts of heat for liquefaction. Mercury, for example, fuses at 39° below zero, wrought iron above + 3280°. The following table contains the fusing points of the substances named:

The fusing points of alloys are often much lower than the fusing point of either of their components. An alloy of two parts bismuth, one of lead, and one of tin, fuses at 200°. The alloy of eight parts bismuth, five of lead, and three of tin, fuses a little below 212°: the addition of one part mercury renders it still more fusible. It is a very convenient substance for taking casts. When this fusible metal, as it is called, is poured upon a marble slab, and broken as soon as it is cool enough to be handled; its surfaces are bright and conchoidal, but the metal is very brittle. Soon, however, it becomes very hot, ceases to be brittle, and the fractured surface becomes granular and dull; this change of temperature must arise from some new molecular arrangement of the particles after solidification; it does not appear to be due to the evolution of latent heat, arising from the solidification of the interior after that of the exterior crust, as has been suggested. The metal after falling to 90° has been known to rise to 150°. The use of fluxes by the metallurgist and others affords numerous illustrations of the fact that mixtures of various bodies fuse at lower temperatures than their component parts do separately. Mixtures of various salts illustrate the same fact :-thus, nitrate of potash fuses at 642°, nitrate of soda at 591°, but a mixture of the two salts in equivalent proportions liquefies as low as 429°.

Under the combined influence of pressure and cold most of the gases have been liquefied and even solidified as noticed under GASES, LIQUE

FACTION OF.

LIQUEFACTION OF GASES. [GASES, LIQUEFACTION OF.] LIQUIDITY is that condition of à material substance in which the particles have a perfect freedom of motion, without any sensible tendency to approach to or recede from one another, except by the action of some external power. Liquidity is therefore comprehended in the condition of fluidity, the latter term being applied as well to gases, and even to the principle of electricity, magnetism, &c., as to water, oil, &c., which are properly called liquids. [FLUID; FLUIDITY.]

The phenomena of capillary or molecular action show that the attractions which constitute what are called the affinities of substances extend to very small distances only from the particles; and hence, when the particles of a substance are situated beyond the limits of such attractive forces, the repulsive power, arising probably from the action of caloric, causes the particles to recede continually from one another, and induces the state of aeriform fluidity. [ATTRACTION.] Now the phenomena of crystallisation seem to indicate that the attraction of affinity is exerted with greater or less intensity according as the like or unlike sides of the particles of a substance present themselves to one another in their mutual approaches; but it is probable that this modification of the attraction of affinity extends to less distances from the centres of gravity of the particles than the general attraction extends hence, when the particles of a substance are, from any cause, brought so near one another that the attraction of affinity is in equilibrio with the repulsive force of the caloric, and at the same time the modification of that attraction caused by the various positions which the particles assume in approaching one another, entirely or nearly vanishes, it should follow that the particles become freely moveable in any direction about one another, whatever be their form; and thus may arise the condition of liquidity.

It may be added that, if the particles of a substance be, by the abstraction of caloric, made to approach still nearer to one another, the attraction of affinity will exceed the force of repulsion; and there will be constituted a solid body, which may be crystallised or not according as the particles approach one another gradually or otherwise: in the former case they may arrange themselves in such positions as to become connected together in one direction by the sides at which the attraction is the greatest; while, if the approach is rapid and is accompanied by agitation, the union of the particles may take place irregularly.

The particles of a liquid are held together with considerable force notwithstanding their freedom of motion, since a small quantity of a liquid has a tendency to take a spherical form when at a distance from any substance for which its particles have greater affinity than for one another: this is very evident in mercury, oil, and water, the first of which on being suffered to fall on a table immediately divides itself into globules, and the others take a like form when a small quantity of either is suspended from a pointed extremity of any object.

The dilatations of water and mercury by the application of heat, as well as the remarkable fact that the expansions of water are equal at temperatures which are at equal distances above and below about 39° Fahr., will be noticed under THERMOMETER. See also HEAT. But the expansions of any liquid, at different temperatures, for equal increments of caloric, are not equal to one another; and indeed the same remark may be extended to solids, as shown under HEAT. The phenomena of molecular action in liquids are noticed under CAPILLARY ATTRACTION, DIFFUSION, &c. See also MOLECULAR ATTRACTION, and for the specific heat of liquids, or their capacity for caloric, SPECIFIC HEAT. LIQUOR OF CADET. [CACODYL.]

LIQUORICE. [GLYCYRHIZA.]

LIRIODENDRIN, a colourless, non-azotised, crystalline substance, found in the stem of the Virginian tulip (Liriodendron tulipifera). It is slightly soluble in water, but very soluble in alcohol and ether. Its composition has not been determined. LIS PENDENS. [NOTICE.] LIST, CIVIL. [CIVIL LIST.] LISTING. [ENLISTMENT.]

LITANY, a collection of prayers and supplications. The term is derived from the Greek (AiTaveía), and was adopted by Christian writers at a very early period. St. Basil tells us that Litanies were read in the church of Neocæsarea, between Gregory Thaumaturgus's time and his own: and St. Ambrose has left a form of Litany which bears his name, still used in Milan. In the early churches the Litanies were said in solemn procession.

In the Common Prayer Book of 1549 (the first book of King Edward), the Litany was placed between the Communion Office and the Office for Baptism, under the title of 'The Letany and Suffrages;' which book also directed it to be said or sung on Wednesdays and Fridays. In the review of the Common Prayer in 1552, the Litany was placed where it now stands, with the direction that it shall be used on Sundays, Wednesdays, and Fridays, and at other times when it shall be commanded by the ordinary. Till the last review, in 1661, the Litany was used as a distinct service, and followed the Morning Prayer; it was then directed and has ever since continued to be read as one office with the Morning Prayer, after the third Collect for Grace.

LITHARGE. [LEAD: Lead and Oxygen.]

LITHIA (LiO). The alkaline base formed by the union of lithium with oxygen. It unites with acids to form an extensive class of salts. [LITHIUM.]

LITHIC ACID. [URIC ACID.]

LITHIUM (L). In its chemical relations this metal more nearly resembles the alkali metals, potassium and sodium, than any others; but it is a kind of connecting link between that group and the next, or metals of the alkaline earths (barium, calcium, &c.) Its existence was first pointed out by Arfwedson (1817), who discovered its oxide when examining a mineral in the laboratory of Berzelius. Its name is

Lithium may be obtained in the metallic state by decomposing its chloride with an electric current generated from five or six pairs of Bunsen's nitric acid battery. It is a white metal, harder than potassium or sodium, but softer than lead. It melts at 356° Fahr., and is not volatile when heated to redness. At common temperatures two pieces may be welded together by pressure. It can be drawn into wire, but is less tenacious than lead. Its specific gravity is 0-5936, hence it is the lightest solid body known; it floats even on the surface of naphtha. It rapidly oxidises in the air, and if assisted by heat burns with a brilliant carmine-tinted flame. It decomposes water in a similar manner to sodium, and ignites when placed in strong nitric acid. The equivalent of lithium is 6.53.

Lithium and oxygen form but one compound, namely:Oxide of lithium (LO). The mineral from which it is to be extracted is reduced to an almost impalpable powder, and then ignited with twice its weight of quicklime in a silver crucible. The resulting mass is next treated with hydrochloric acid, then with sulphuric acid, and the sulphate of lithia thus formed dissolved out from sulphate of lime | by washing with water; a small quantity of oxalate of ammonia is now added to remove lime that may have been dissolved, and sulphuric acid thrown out of solution by the addition of baryta water. On evaporating the filtered liquid the lithia separates out in grains. If necessary, it may be fused in a silver crucible, vessels of platinum being rapidly corroded by it. Hydrate of lithia is not so soluble in water as the hydrates of potash or soda are. It has a strong caustic taste, and turns vegetable reds to blues. In the fused state it is white, transparent, has a crystalline structure, does not deliquesce in the air, and dissolves in water with disengagement of heat.

Lithium and chlorine form :

Chloride of lithium (LCI). It is readily made by dissolving the oxide in hydrochloric acid. On evaporation the solution yields cubical crystals, very soluble, exceedingly deliquescent, and containing four equivalents of water of crystallisation.

Iodide of lithium (LI+6HO) crystallises in needles, and fluoride of lithium in small opaque grains.

Sulphide of lithium is formed in the same way as sulphide of sodium, and much resembles that compound.

Sulphate of lithia (LO,SO, + Aq). On evaporating the solution of this salt, obtained as described under oxide of lithium, tabular crystals of the above composition are obtained.

Carbonate of lithia (LO,CO2) is precipitated when carbonate of ammonia is added to a strong solution of chloride of lithium. It may be washed with alcohol, in which it is insoluble. It is slightly soluble in water, the resulting solution having an alkaline reaction. On the application of heat to the dried salt it fuses, and solidifies on cooling to a white transparent mass of pearly lustre and crystalline fracture. Carbonate of lithia has been recommended to be administered as a solvent for calculi in the bladder. It certainly effects the solution of uric acid most rapidly when triturated with that substance in a mortar containing a little water; but as many calculi do not contain uric acid, and as most of those that do contain it have an external coating of phosphates, it follows that the carbonate of lithia, being an alkaline substance, may do more harm than good if administered indiscriminately. Double phosphate of lithia and soda.-When phosphate of soda is added to a solution of a lithium salt no precipitate is at first produced; but on evaporating to dryness the above compound remains as a white powder, almost insoluble in water, and quite insoluble in dilute aqueous solutions of the alkaline phosphates. Before the blowpipe, with carbonate of soda, the double salt fuses to a clear bead, transparent when hot but opaque when cold. A fused specimen examined by Berzelius contained NaO,LO,PO,, but generally its composition is very variable, probably on account of the two bases, lithia and soda, being capable of replacing each other.

Tests for lithium.-Salts of lithium are readily fusible in the blowpipe flame, imparting to it a carmine red colour, and attacking the platinum wire holder or other platinum vessel in a characteristic corrosive manner. Their presence is further confirmed by forming the carbonate and double phosphate in the way already mentioned.

LITHOFELLIC ACID. (CHO). Lithofellinic acid. The once celebrated bezoar-stones-intestinal calculi of certain animals-almost wholly consist of this acid. To isolate it, the stones [BEZOARS], are reduced to powder and boiled in alcohol, the dark solution decolorised with animal charcoal and evaporated, when the lithofellic acid crystalises out in small, colourless, transparent six-sided prisms. It may also be decolorised by precipitating its alkaline solution with hydrochloric acid, washing, drying, and crystallising from alcohol.

Lithofellic acid is insoluble in water, slightly so in ether, and very soluble in alcohol. Heated to 401° Fahr. it melts, and at a little higher temperature is converted into a resin, the fusing point of which is only 230° Fahr. In this particular, and in the fact that it is readily soluble in solutions of the alkalies and their carbonates and in acetic acid, lithofellic acid is easily distinguished from cholesterin, a body that otherwise it much resembles.

Submitted to dry distillation, it yields an oily acid, termed pyrolithofellic acid (CH3.0).

Lithofellic acid combines with bases to form lithofellates, a class of compounds that have not been much studied. The silver salt appears to contain CH,Ag O..

LITHOGRAPHY, the art by which impressions or prints are obtained by a chemical process from designs made with a greasy material upon stone. It has therefore been properly termed chemical printing, to distinguish it from all other modes of obtaining impressions, which are mechanical. In printing from an engraving on a copper or steel plate, the ink is delivered from the incisions made therein with the graver or etching-needle. An engraving on wood, on the contrary, gives its results from the projecting surface of the block, or those parts which are not cut away by the graver. The lithographic process differs from both these modes, the impressions being obtained (by strict attention to chemical affinity) from a level surface. The art of lithography was first practised by the inventor Alois Senefelder, in 1798, the peculiar property on which it depends having being discovered by him a few years earlier. [SENEFELDER, ALOIS, in BIOG. Div.] There are various styles of lithography, as will presently be seen; but the principle of the art is uniformly the same, being, as we have said, based upon that of chemical affinity.

The stone best calculated for lithographic purposes is a sort of calcareous slate, found in large quantities on the banks of the Danube in Bavaria, the finest being that found at Solenhofen, near Munich. Stones much resembling the German have been found in some parts of Devonshire and Somersetshire, and also in Ireland; but the stones found in this kingdom have been proved to want some of the essential qualities of those brought from Germany, which are therefore, at least for artistic works, exclusively used. Even the Bavarian stones vary much in quality, all the strata not being equally good: some are too soft, and others are rendered unfit for use by the presence of chalk, flaws and veins, and fossil remains. A good stone is porous yet brittle, of a pale yellowish-drab, and sometimes of a gray neutral tint. The stones are split or sawn into slabs varying from 1 to 3 inches in thickness, which are then cut or squared into the different sizes necessary for use, and the face or upper surface of each is made level. In this state are the stones sent from the quarry; but further preparation is yet necessary to fit them for the immediate use of the artist, and they are either grained or polished, according to the nature of the work they are intended to receive. The mode of preparing a grained stone, as it is called, is this:-A stone, being laid flat on a table, has its surface wetted, and some sand sifted over it through a very fine wiresieve. Another stone is laid with its face downwards upon this, and the two are rubbed together with a circular motion, to produce the requisite granulation, which is made finer or coarser, to suit the taste or intention of the artist. The stones thus prepared are used for drawings in the chalk manner, or for imitations of those produced with the black-lead pencil. Great care is requisite in this mode of preparation, to keep the granulation uniform and the surface free from scratches, the presence of which would otherwise much disfigure the future work. Writings, imitations of coloured drawings, etchings, pen and ink sketches, &c., require the face of the stone to be polished, which is effected by rubbing it with pumice-stone and water, or pumice stone dust and water applied with rags.

The

The two principal agents used for making designs, writings, &c., on stone, are called lithographic chalk and lithographic ink. They are composed of tallow, virgin-wax, hard tallow soap, shell-lac, sometimes a little mastic or copal, and enough lampblack to impart a colour to the mass. These are incorporated by a peculiar process of burning in a closely-covered saucepan over a fire, and the whole is ultimately cast into a mould, and receives the form calculated to fit it for use. ingredients are the same in the chalk and the ink, but the proportions are varied, and a little Venice turpentine is often added in the latter. The chalk is used as it comes from the mould in a dry state, but the ink is dissolved by rubbing, like Indian ink, in water, and is used in a pen or camel-hair pencil. It will be perceived that it is the presence of the soap in this greasy material which renders it soluble in water.

To render the lithographic process intelligible, let it be supposed that the artist now completes a drawing with the chalk just described, upon a grained stone, much as he would make a drawing in pencil or chalk upon paper. If, while in this state, a sponge filled with water were passed over the face of the stone, the drawing would wash out, the chaik with which it is made being, as we have seen, soluble in water, by reason of the soap which it contains. Before therefore it is capable of yielding impressions, a weak solution of nitrous acid is poured over it, which unites with and neutralises the alkali or soap contained in the chalk, and renders it insoluble in water. After this the usual course is to float a solution of gum over the whole face of the