LITHOGRAPHY

LITHOGRAPHY,

THE art of taking impressions from drawings or writings made on stone.

The principles on which this art is founded are, 1st, The quality which a compact granular limestone has of imbibing grease or moisture; and, 2dly, The decided antipathy of grease and water for each other.

A drawing being made on the stone with an ink or crayon of a greasy composition, is washed over with water, which sinks into all the parts of the stone not defended by the drawing. A cylindrical roller, charged with printing-ink, is then passed all over the stone, and the drawing receives the ink, while the water defends the other parts of the stone from it on account of its greasy nature.

This process, therefore, depends entirely on chemical principles, and is thus distinct from letter-press or copper-plate printing, which are altogether mechanical. On this account it has in Germany been called chemical printing; and, as metallic plates can be prepared to be printed from in a similar manner, Lithography is considered only as a branch of chemical printing.

I. HISTORY OF LITHOGRAPHY.

The invention of Lithography was the result of accident. Its inventor, Alois Senefelder, the son of a performer at the Theatre-Royal of Munich, was placed for education in the University of Ingolstadt, as a student of jurisprudence; but, after his father's death, he attempted a theatrical career. Not succeeding in this, he became an author, though his poverty prevented him from publishing his works. He now tried many plans with copper-plates and compositions, as substitutes for letter-press, in order to be his own printer. He found, in the course of his experiments, that a composition of soap, wax, and lamp-black, formed a good material for writing on his plates; that, when dry, it became firm and solid, and that it resisted aquafortis. Wanting facility in writing backwards on the plates, he got some pieces of Kilheim stone, as cheap materials, on which he could practise after polishing their surfaces. One day being desired by his mother to take an account of some linen about to be sent to be washed, and having no paper at hand, he wrote the account on a polished stone, with his composition ink, intending to copy it at his leisure. When he was afterwards about to efface this writing, it occurred to him that he might obtain impressions from it; and, having eaten away the stone with acid for about the hundredth of an inch, he found that he could charge the lines with printing-ink, and take successive impressions. This new mode of printing appeared to him very important, and he persevered through all difficulties in applying his discovery to practical purposes, and in improving it.

In the course of many experiments, he found that it was not necessary to have the letters raised above

the surface of the stone, but that the chemical principles by which grease and water are kept from uniting, were alone sufficient for his purpose. This point obtained, Lithography may be said to have been fully discovered. All that was required was the improvement of the materials, and the mode of working with them, and the construction of a proper press for taking the impressions.

The perseverance with which he followed up his experiments, in order to overcome the difficulties which successively arose in his progress, is astonishing, and the more so, considering the total want of method in his proceedings. Often has he wasted months in surmounting a difficulty which a little knowledge, or a very little reasoning, would have enabled him to conquer immediately. His uniform plan seems to have been, to try the first thing that came to hand, and so on in succession, till chance rewarded his assiduity by presenting to him the material suited to his purpose.

The first essays to print for publication were some pieces of music, executed in 1796; afterwards he attempted drawings and writings. The difficulty he had in writing backwards led him to the process of transfer, and the use of dry soap, which was found to leave permanent traces, which would give impressions, naturally led to the mode of chalk drawings.

Having made considerable improvements, Mr Senefelder obtained, in 1799, a patent privilege for Bavaria, when he made known his process, and afterwards entered into partnership with Mr André, of Offenbach, who proposed to establish presses, and take out patents at London, Paris, and Vienna. For this purpose Senefelder came to London with a brother of André's, and the invention having been much spoken of, under the name of Polyautography, most of the principal English artists made trials of it. Unfortunately, however, the art of printing from the stones was not then fully understood, and the difference between the materials of Germany and those of England, used both for the purposes of drawing and printing, caused constant failures, and the artists in succession abandoned the practice of it. To this cause is to be attributed the unpopularity of Lithography till recently in England, as it was left entirely in the hands of amateurs, whose productions, generally speaking, did no credit to the art, and whose faults were in some degree supposed to be those of the art itself.

In August 1800, Senefelder, who had now separated from André, went to Vienna, where, after much difficulty, a patent was obtained, and extensive preparations were made, for applying his process to print cottons; but bad management, and some unfortunate circumstances, prevented his success, and he returned to Munich in 1806, leaving the establishment in other hands.

Mr Mitterer, Professor of Drawing at the Public School at Munich, now (1806) practised Lithography

to multiply copies for the pupils, and is said to have invented the chalk composition in its present form, or at least to have improved it greatly.

From this period the practice of the art has extended and improved rapidly, and more particularly at Munich, where several establishments were formed, for the purpose of applying it to the fine arts, as well as for printing writings and official forms, for the different departments of the government.

In October 1809, Senefelder was appointed Inspector of the Royal Lithographic Establishment at Munich, for printing from stone a complete map and survey of Bavaria; since which period he has devoted his time to experiments, and to writing the history of his invention. Among other points of improvement to which his attention has been directed, is a substitute for the stones, which are inconvenient to use on account of their weight, and they are also liable to break in the press, when used without due caution, or when they contain flaws. For this purpose he has made a composition of drying oil, finely ground earth, and other substances, which is thinly spread over pieces of parchment; but it has not hitherto been found to answer. The surface cracks after repeated wetting and exposure to the power of the press, and the printing-ink is then taken in the cracks, and spoils the impressions. Thus a very small number only of good impressions can be obtained. A public exhibition of printing from this stone paper was made in London, on the 23d July 1821, by a partner of Mr Senefelder; but the result was not such as to induce much confidence in the ultimate success of the trials to form this desirable substitute of a light material for a heavy one.

In England Lithography can scarcely be said to have been entirely given up since its first introduction in 1800, although it was but little practised or thought of after 1805, till its revival at the latter end of 1817; since then it has been more generally attended to, and some of the establishments having now become well acquainted with the process of printing, specimens have been produced in England equal to those of any other country.

In France but little was done in lithography till 1815, when it was established at Paris by Lasteurye, and being taken up by good artists, it soon attained great excellence. About the same time it extended to Russia and other parts of Europe.

II. DESCRIPTION OF THE MATERIALS, AND THE MODE OF PREPARING THEM.

1. Of the Stones, and the manner in which they are prepared to receive the Drawings.

As calcareous stones will all imbibe grease and moisture, and effervesce with an acid (the use of which will appear when we speak of the process of printing), they are all capable of being used for Lithography. Those are best adapted to the purpose which are very compact, of a fine and equal grain, and free from veins, or imbedded fossils or crystals.

The quarries of Solenhofen, near Pappenheim in Bavaria, furnished the first plates, and none have as yet been found to equal them in quality. They are of a very uniform pale yellowish white colour. The

fracture is perfectly conchoidal. The beds divide into thin portions of considerable size, with perfectly flat surfaces, and were on this account carried to Munich and other places for paving kitchens and halls, and thus came in the way of Senefelder, when he discovered the chemical process of printing.

The stones of this quarry vary in their quality, but the best are in great abundance. Generally speaking, the hardest are the best, provided they are quite uniform in texture. Such are necessary for fine chalk drawings, softer ones may do for ink, or for coarser drawings in chalk.

In France, stones have been found near Chateauroux (Département de l'Indre), of a similar colour to those of Solenhofen, and even harder and of a finer grain, but they are so full of large spots of a softer nature, that it is scarcely possible to get one perfect of a greater size than twelve inches square.

In England a stone has been used for Lithography which is found at Corston near Bath. It is one of the white lias beds, but not so fine in grain or so close in texture as the German stone, and therefore far inferior. But it is good for transfers, and does tolerably well for ink drawings or writings. Another stone, found near Stony Stratford, is also used; but it is of a brownish grey tint, and too dark in colour to show the effect of the drawing with sufficient clearness.

To bear the pressure used in taking the impressions, a stone twelve inches square should be at least one inch and a quarter thick. The thickness must increase with the size of the stone, but two inches and a half are a thickness sufficient for stones of three feet by three feet and a half.

The stones, when sawn to a proper size and thickness, are ground level by rubbing two of them face to face with water and sand, and very carefully examined with a straight-edge, to ascertain that they are perfectly level in all directions. This applies only to the side which is afterwards to receive the drawing, as the natural division of the stone is sufficiently true for the back.

To prepare them for chalk drawings, two stones, which have been perfectly levelled, are well washed in order to free them from any of the coarser grains of sand which have been previously used upon them. They are now to be placed on a board over a trough, and a small quantity of water and very fine sand being strewed over the surfaces, they are to be rubbed face to face, adding occasionally a little fresh sand and water. The best sort of sand in England is that called silver sand, for preparing the stone, and the common brown sand for giving a fine grain. The sands must be passed through a sieve of the fineness required, which will vary with the nature of the drawing; and the greatest care must be taken to have the sieves perfect, and to prevent any coarser particles of sand from being mixed with the rest. A single grain would fill the stone with innumerable scratches, which would all appear in the drawing. The upper stone is in this operation moved in small circles, carefully and equally all over the under one, taking care not to move the one beyond the edge of the other, or the faces would become rounded. When the grain is equal, and sufficiently fine, the stones are carefully

washed, and wiped with a clean cloth. The stone, thus prepared, should have, when dry, a perfectly uniform appearance in the colour and grain, and resemble a sheet of vellum. It should be free from scratches, and have no shining parts. The upper stone is always the finer grained of the two.

Sometimes dry sand alone is used, but it is better to use it with water.

To prepare the stones for ink drawings or writings, the process just described is first followed; they are then well washed to get rid of the sand, and the same operation of rubbing two together is continued with powdered pumice-stone and water. When perfectly smooth, they are again washed, and afterwards separately polished with a large piece of fine pumice-stone with a circular motion. The polish now given to the stone should be such as to show the reflection of objects to the eye placed close to the stone, and looking along it towards the light.

When a writing or drawing has been fully used, and the stone is to be again prepared, sand is strewed over the surface, and it is sprinkled with water, and rubbed with another stone as before described, till the drawing has disappeared. It must then be washed with aqua fortis diluted with twenty times its bulk of water. This is absolutely necessary to destroy the lines, which would otherwise partially re-appear in printing a second drawing from the same stone. After this the stone is again prepared for a new drawing with fine sand in the manner before described.

Ink drawings sink deeper into the stone than the chalk, and require the stone to be more ground away to efface them. The longer drawings remain on the stone, the deeper the ink or the chalk penetrates.

2. Lithographic Ink and Chalk.

For these materials the union of several qualities is required, and as no single substance possesses them all, it is necessary to combine several substances together.

Lithographic Ink.

A great many different receipts have been given, but as only two sorts are wanted, namely, one for writing on the stone, and one for transfer, it will be sufficient to give one of the most approved of each kind, and to point out the cause of any defect, with the means of remedying it. These defects are generally to be attributed to some fault in the preparation.

Composition of Lithographic Ink for Drawing on the Stone.

Tallow candle,	2 oz.
Virgin wax,	2 oz.
Shell lac,	2 oz.
Common soap,	2 oz.
Lamp-black, about one-twentieth of the whole.

These materials are prepared in an iron saucepan with a cover. The wax and tallow are first put in and heated till they ignite; while they are burning the soap must be thrown in in small pieces, one at a time, taking care that the first is melted before a second is put in. When all the soap is melted, the in-

gredients are allowed to continue burning till they are reduced one-third in volume. The shell lac is now added, and as soon as it is melted, the flame must be extinguished. It is often necessary in the course of the operation to extinguish the flame, and take the saucepan from the fire, to prevent the contents from boiling over; but if, after the process above described, any parts are not completely melted, they must be dissolved over the fire without being again ignited.

Sometimes a larger proportion of wax is used, when only half of the soap is put in, and the burning goes on till the quantity is reduced one-half. The remainder of the soap is then added over a fire which keeps the mass melted without igniting it.

If the ink, in this state, is broken when cold, the pieces should adhere very slightly when pressed together between the fingers. If it works between the fingers like wax, it must be again burnt for a short time; if it is too brittle, and the broken parts will not adhere at all together by pressure, some more soap must be added in a second burning.

It should now dissolve, though with difficulty, by rubbing with warm water. The lamp-black, of the finest quality, must now be mixed with it, which is done while it is melted over a slow fire, adding small portions of the black at a time, and stirring them well together. The black increases its solubility for use, but too much is detrimental. When complete, it should, in its fracture, have the appearance of Indian ink, though it is softer. When the black is mixed with it, it must be cast on a marble slab and pressed with a heavy weight. The following rules for remedying defects in the ink are given by M. de Raucourt in his Manuel de la Lithographie, which is the most useful book yet published on the subject. It has been translated into English by Mr Hull-mandel.

Defects of the Ink.

The ink is not soluble.
It is soft and attaches itself to the fingers.

Some time after dissolving it in water it becomes thick and slimy, and requires a continual addition of water in order to be enabled to draw with it.

The ink is not compact, and is full of bubbles.

The ink has no tenacity. It seems composed of scorias.

Remedies.

Add soap.
Burn it more.

This is the defect of almost all inks; it proceeds from its not being sufficiently burnt. Burn it more.

It has been cast too hot on the marble slab; cast it again when it is less hot, and lay a heavier weight upon it.

Both these defects may proceed either from its being too much burnt, or from its containing too much black; in either case, add equal portions of wax and soap, and melt on a slow fire.

Keeping in view the principles here pointed out, any one can, after a few trials, make good Lithographic ink.

This is composed of the same materials as the preceding, but must be less burned. It will therefore be softer, and it must also be afterwards melted and mixed with a little more wax and thick varnish, such is described hereafter in speaking of the printing inks.

This should have the qualities of a good drawing crayon, it should be even in texture, and carry a good point. It is, however, difficult to avoid making it too soft and greasy on the one hand, and too brittle on the other. For the chalk, as for the ink, more or less of the soap, wax, and tallow, may be used as the extent of the burning may render necessary, and the remedies pointed out for defects of the ink will enable the operator to judge of what is wanting.

The following proportions are the best:

Common soap,	1½ oz.
Tallow,	2 oz.
Virgin wax,	2½ oz.
Shell lac,	1 oz.

The manipulation is similar to that for the ink. It is well, however, to throw in a little of the wax just before the flame is extinguished. Less black must be mixed with the chalk than with the ink, its only use being to colour the drawing, so that the artist may see the lines he traces.

When the whole is well mixed, it should be poured into a mould, and very strongly pressed to prevent any bubbles, which would make the texture irregular.

With these materials the artist proceeds to work on the prepared stone, taking care first to wipe the stone with a clean dry cloth. The ink being rubbed with warm water like Indian ink, is used on the polished stone; and it is to be observed, that a gradation of tints can be obtained only by varying the thickness of the lines, and the distance at which they are placed apart; as the line traced by the ink being sound and unbroken throughout, receives the printing ink all over. Hence it follows, that the artist cannot gain any advantage by diluting the ink for the lighter tints of the drawing, as the printing ink will take equally upon all the lines, and at once render all of them equally black. The object of the artist is to mix the ink to that consistency, which, while it works freely, shall yet be strong enough to stand perfect through the process of printing. A consistency, a little stronger than writing ink, is sufficient for this purpose.

The chalk will not hold upon the polished stone.

The grained stone, prepared for chalk, being carefully wiped to free it from dust, must be drawn upon with the crayon as common drawing chalk is used on paper. The subject may be traced on the stone with lead pencil or red chalk, but care should be taken to do this very lightly, so as not to fill up any of the grain of the stone. In drawing, the degree of pressure of the hand will vary the strength of the tint, and it is desirable to give the requisite strength at once; as the surface of the stone is a little alter-

ed by receiving the chalk, and hence it does not take any additional lines with the same equality. Practice is necessary to give a command of the material, as it does not work quite like the common crayon, there being great difficulty in keeping a good point. There is also much difficulty in obtaining the finer tints sound in the impression; and for the light tints, it is necessary to put the chalk in a reed, as the metal port-crayon is too heavy to draw them, even without any pressure from the hand; and therefore the artist cannot draw them with freedom, as his touch will be unsteady, by being obliged to support the pencil from the stone.

It is necessary to observe the grain with which the stone is prepared, which should vary with the fineness of the drawing. Several pieces of chalk should be prepared to use in succession, as the warmth of the hand softens it.

It is useful to cut the chalk to the form of a wedge rather than a point, as it is less likely to bend in that form.

Small portions of the point will break off during the drawing; these must be carefully removed with a small brush.

The best sort of printing press for Lithography is Printing represented in Plate XCV. the drawings being taken Press. from one used by Mr Hullmandel.

Fig. 1. Is a side elevation of the press, with the scraper partly down.

2. A cross section through the middle.

3. A horizontal plan of the upper part.

4. Detail of the manner in which the scraper is held down during the impression.

5. End elevation of the press.

6. To explain the manner in which the centre of motion of the scraper is raised and lowered.

The press consists of a strong frame, having on the upper part a platten, or bed, a, to receive the stone, and which is moved along grooves in the upper part of the frame by means of a star-wheel, b, to the axle of which is fixed a cylinder, c. On this cylinder the straps, dd, are gathered, which work over the pulleys, e, fixed to the bed.

When the stone is placed on the bed, and ready for the impression, the friquet, or cover, f, of the bed, is brought down from the position marked by the dotted outline in fig. 1, and shut over the stone, as shown in the same figure. This cover consists of a strong piece of calf's skin, stretched by screws with nuts and hooks, which catch hold of an iron rod sewed along one end of the skin. The other end of it is fixed to the opposite end of the frame. (See fig. 3.) The cover is fixed to the bed by hinges, g, which can be screwed at different heights, according to the thickness of the stones. When the cover is opened, it rests against the frame, h, which can be adjusted to different heights. (See figs. 1 and 5.)

The cross piece, i, having the scraper, k, fixed in it, is now brought down, and the catches, l, lock into the upper part of the piece, m, sliding between the grooved upright, n. This is shown more in detail in fig. 4, the upper part, where the catches lock, is of iron, and has a joint and handle to pull it out

when the scraper is to be unlocked. A spring, $\backslash sigma$, keeps it generally in an upright position to be ready to hold the catches, $l$.

When the scraper is locked down, the printer sets his foot on the treadle $p$ of the lever, which presses the scraper with great power on the stone. The pressure is by a double lever, having a connecting rod, $q$, which can be adjusted so as to bring the upper arm $r$ nearer to the treadle, when an increase of pressure is required, or a thinner stone is placed on the bed, which makes it necessary to bring the scraper lower down. The arm $r$ passes through an iron frame on the sliding piece $n$, and thus brings it down when the treadle is depressed. The hook $s$ holds down the treadle during the impression.

The star-wheel $b$ is now turned round, and by this motion the bed is drawn under the scraper, and the impression is taken. The bed passes over a roller, $t$, which is placed with its centre directly under the scraper. See fig. 2.

As the stones are not always of the same thickness, the scraper must be brought to different heights. Fig. 6 shows an adjusting screw for the purpose of regulating the end farthest from the catches, there being a sliding piece between the grooved uprights, $u$, in which the centre is fixed, on which the cross piece $i$ turns. The iron $v$, fig. 2, stops the cross piece and scraper from falling back.

When the bed has been drawn out, the printer releases the treadle, which is raised up by the balance weight, $w$, and the scraper being unlocked and thrown back, the bed is drawn to its first position by the weight, $x$.

As the surface of the stone is not always quite parallel to the bed, a simple contrivance has been adopted to allow a self adjustment of the scraper, which is allowed to turn on the centre, and pressed down by a spring acting on each end, but yielding if necessary at either. It is shown by the dotted lines in fig. 2. The screw $y$ presses the scraper lower, or raises it if required.

The scrapers are made of beech wood.

The Roller.

The roller for inking the drawing is of the form represented, Plate XCV. fig. 7. The length may vary, but it ought to be full four inches in diameter. It is covered with flannel, rolled tightly three or four times round, and nailed at the ends. It is then covered with a stretched calf-skin, fitting quite tight. The seam must be made neatly with the boot-maker's closing stitch. The ends of the leather are gathered with a string, and tied round the projecting ends of the roller. Loose handles A, A, made of thick leather, are put on these ends when it is used. The leather must be put on the roller with the rough side outwards.

5. Printing Ink.

The printing ink is composed, as other printing inks are, of oil, varnish, and very fine lamp-black, well mixed together. To prepare the varnish, a saucepan is about half filled with pure linseed oil, and heated over a fire, till it ignites from the flame of a piece of burning paper. It should then be allowed to burn till it is reduced to the degree re-

quired; and if, during the operation, there appears danger of its boiling over, it must be immediately taken off the fire, and the cover, which ought to fit quite close on the saucepan, must be put on to extinguish the flame. This is to prevent accidents; and the operator cannot be sufficiently cautioned against the danger attending the burning of the varnish, which ought never to be performed in a room with a boarded floor, or indeed in any part of a house. Wet sacks are the best things to put out the flame in case of accident.

Several inks must be prepared, differing in the degree of viscosity, or thickness of the varnish from which they are made, and the quantity of black mixed with them. The longer the oil is burned, the thicker the varnish becomes.

The thinnest varnish is burned till it has lost nearly one-fourth of its volume.

The next till it is reduced one-third.

The thickest till it is reduced one-half.

These directions are to be considered as very general ones; and the state of the varnish is best judged of during the burning, by taking out some with a spoon, and letting a drop fall on a cold earthenware plate, and trying its degree of viscosity with the finger. The thinnest sort should be like common honey, the other should draw out in strings, which will be longer as the varnish is thicker. The thickest will draw out in strings two or three feet long.

It is quite essential to have the oil pure, and the saucepan perfectly clean, and to keep the varnish in clean close jars in a cool place.

It is best not to make the varnish long before it is wanted; for if any decomposition takes place in it, the drawing will be spoiled by the printing ink.

The black is mixed with the varnish on a grinding stone with a muller, in small successive quantities; care being taken that the first portion of black is equally mixed with the varnish before a second is added. In the thickest inks this requires considerable labour.

By mixing the varnishes together, any degree of stiffness of the ink may be obtained; and by putting more or less black, its thickness is regulated.

The printer must always have by him several small pots, each containing a different printing ink, to be used as occasion requires. A small quantity, not more than the size of a hazel-nut, should be used at a time, for it is desirable to charge the roller with as small a quantity as possible. It must be worked well on the colour table with the roller in all directions, that it may be equally distributed all over the roller.

Ink drawings are generally printed with a stiffer ink than chalk drawings.

6. Preparation of the Stone for Printing.

The drawing being finished on the stone as before described, is sent to the Lithographic printer, on whose knowledge of his art the success of the impressions entirely depends. The first process is to etch the drawing, as it is called. This is done by placing the stone obliquely on one edge over a trough, and pouring over it very dilute nitric acid. It is poured on the upper part of the stone, and runs down all over the surface. The stone is then turned, and placed on the opposite edge, and the etching water,

being collected from the trough, is again poured over it in the same manner. The degree of strength, which is little more than one per cent. of acid, should be such as to produce a very slight effervescence; after the etching water has lain on the stone for a second or two, its strength must vary according to the heat of the atmosphere, and the degree of fineness of the drawing. It is desirable to pass the etching water two or three times over the darkest parts of the drawing, as they require more etching than the lighter tints. Some stones also, and different chalks, require different degrees of strength of the acid, and experience alone can guide the Lithographer in his practice on this point. Chalk drawings require weaker acid than the ink.

The stone is now carefully washed, by pouring clean rain-water over it, and afterwards with gum-water; and when not too wet, the roller, charged with printing ink, is rolled over it in both directions—sideways, and from top to bottom, till the drawing takes the ink. It is then well covered over with a solution of gum-arabic in water, of about the consistency of oil. This is allowed to dry, and preserves the drawing from any alteration, as the lines cannot spread, in consequence of the pores of the stone being filled with the gum. After the etching, it is desirable to leave the stone for a day, and best not to leave it more than a week, before it is printed from. In some establishments a few proofs are taken immediately after the drawing is etched, but it is better not to do so.

The operation of the etching requires great nicety, and must be done quickly. If the drawing is etched too strongly, the fine tints disappear; if too weak, the printing ink mixes with the darker parts, and the drawing runs into blots. A soft stone requires weaker acid than a hard one, if they are equally pure in quality. The differences in the composition of the stones also require differences in the strength of the etching water, so that no strict rules can be given.

The effect of the etching is, first, to take away the alkali mixed with the drawing chalk or ink, which would make the drawing liable to be affected by the water; and, secondly, to make the stone refuse more decidedly to take any grease. The gum assists in this latter purpose, and is quite essential to the perfect preparation of the surface of the stone.

7. Printing.

When the stone is to be printed from it is placed on the bed or platten of the press; at this time a proper sized scraper for the printing is very carefully adjusted to the surface of the stone. The gum on the stone is now sprinkled with rain-water, and being gradually dissolved, and a wet sponge passed lightly all over it, the printer works the ink which is on the colour table placed beside him, with the roller in all directions till it is equally spread and thinly all over the roller. He then (the stone being wet) passes the roller all over the stone in both directions, observing (as his experience enables him to do) that all parts of the drawing take the ink in due proportion. The roller should be applied with an equal motion and pressure, which must be regulated according to the mode in which the drawing takes the ink; if it does not take it readily, the pressure must be increased, and the roller moved more slowly.

The roller should turn freely as it passes over the stone; if it slips, the cause is either that the stone is too wet, or that too much of the gum remains upon the stone; in the first case, a drier sponge will correct the evil; in the second, the stone must be again washed with a little water; but this must be done with caution, as the gum should not be entirely washed off the stone.

At first the drawing receives the ink with some difficulty, and it is frequently necessary to wet the stone and roll it in several times, before it will take the ink readily. Care must now be taken not to wet the stone too much; the less dampness the better, provided it is sufficient to keep the stone from taking the ink in the parts where there is no drawing; at all events, no drops of water should be seen on the stone, as they spoil the printing ink, and also are imbibed by the roller, which therefore becomes unfit for use. After the drawing is thus rolled in, the sheet of paper is placed on the stone, and the impression taken in the manner described in the account of the press. When, after the impression, the paper is taken up, the stone appears dry, the moisture having been imbibed by the paper. It must be again wetted with a damp sponge, and rolled in with ink as before, taking care to work the roller well on the colour table each time before applying it to the stone.

Generally the first few impressions are imperfect, from the drawing not taking the ink fully, but this is gradually corrected.

During the printing some gum must always remain on the stone (though it will not be visible), otherwise the ink will take on the stone, and also spoil the drawing. If, by too much wetting or by rubbing too hard with the sponge, the gum is entirely removed, some fresh gum-water must be laid on. If the stone has, in the first instance, been laid by with too small a quantity of gum, and the ink stains the stone on being first applied to it, gum-water must be used to damp the stone instead of pure water. Sometimes, however, this may arise from the printing ink being too thin, as will appear below. If some spots on the stone take the printing ink, notwithstanding the above precautions, some strong acid must be applied to them with a brush, and after this is washed off, a little gum-water is dropped on the place. A steel point is here frequently necessary to take off the spots of ink.

The edges of the stone are very apt to soil, and generally require to be wiped with an old sponge or rag after the rolling in. They must also frequently have an application of acid and gum, and sometimes be rubbed with pumice-stone.

Chalk drawings are much the most difficult to print. After this general description of the printing, the following development of the principles on which it is regulated, and notice of the difficulties which arise in its progress, will be found useful.

An ink which is too thin, and formed of a varnish not sufficiently burned, will soil the stone, notwithstanding the proper precautions are taken of wetting the stone, and preparing it properly with acid and gum.

Ink which is too stiff will tear up the lighter tints of the chalk from the stone, and thus destroy the drawing.

The consideration of these circumstances leads us at once to the principles of the printing. These

accidents arise at the extreme points of the scale at which the printing inks can be used, for it is evident, that the only inks which can be employed are those which are between these points, that is, thicker than that which soils the stone, and at the same time thinner than that which takes up the drawing. Lithographers are sometimes unable to print in very hot weather, the reason of this may be deduced from the above. Any increase of temperature will diminish the consistency of the printing ink; the stone will therefore soil with an ink which could be safely used at a lower temperature; hence a stiffer ink must be used. Now, if the temperature should increase so much that the stone will soil with any ink at all less thick than that which will take up the drawing, it is evident that the printing must cease till a cooler temperature can be obtained; for, as the drawing chalk is affected equally with the printing ink, the same ink will tear up the drawing at the different degrees of temperature.

This, though it sometimes occurs, is a rare case; but it shows that it is desirable to draw with a chalk or ink of less fatness in summer than in winter; and also, that if the printing-room is in winter artificially heated, pains should be taken to regulate the heat as equally as possible.

We will now enumerate some other difficulties which are not referable to the above general principle.

If the pressure of the scraper is too weak, the ink will not be given off to the paper in the impression, although the drawing has been properly charged with it. Defects will also appear from the scraper being notched, or not correctly adjusted, or from any unevenness in the leather or paper.

Inequalities in the roller will cause the drawing to receive the ink unequally, and if the roller or its leather is too hard, it will not ink the drawing clearly.

After printing a considerable number of impressions, it sometimes happens that the drawing takes the ink in dark spots in different parts. This arises from the printing ink becoming too strongly united with the chalk or ink of the drawing, and if the printing is continued the drawing will be spoiled. A little consideration will show us the reason of this accident. The printing ink readily unites with the drawing, and being of a thinner consistency, it will by repeated applications accumulate on the lines of the drawing, soften them, and make them spread. In this case it is necessary to stop the printing, and let the stone rest for a day or two, for the drawing to recover its proper degree of hardness. If the drawing should run smutty from any of the causes before enumerated, the following mixture will clean it.

Take equal parts of water, spirits of turpentine, and oil of olives, and shake them well together in a glass phial, until the mixture froths, wet the stone, and throw this froth upon it, and rub it gently with a soft sponge. The printing ink will be dissolved, and the whole drawing also will disappear, though, on a close examination, it can be distinguished in faint white lines. On rolling in again with printing ink, the drawing will gradually reappear as clear as at first.

Accidents sometimes occur in the printing, from the qualities of the paper. If the paper has been made from rags which have been bleached with oxy-muriatic acid, the drawing will be incurably spoiled

after thirty impressions. Chinese paper has sometimes a strong taste of alum; this is so fatal as sometimes to spoil the drawing after the first impression.

When the stone is to be laid by after printing, in Preserving order that it may be used again at a future period, Ink. the drawing must be rolled in with a preserving ink, called by Senefelder, Aetzfarbe, as the printing inks would, when dry, become so hard, that the drawing would not take fresh printing ink freely. The following is the composition of the preserving ink.

Thick varnish of linseed oil,	2 parts.
Tallow,	4 do.
Venetian turpentine,	1 do.
Wax,	1 do.

These must be melted together, then four parts of lamp-black very carefully and gradually mixed with it, and it must be preserved for use in a close tin box.

Very good effects are produced in Lithographic prints, by printing from two or more stones with different coloured inks. This is managed by preparing a composition of

Wax,	2 parts.
Soap,	1 do.
A little vermillion.

Melt them in a saucepan, and cast them into sticks. This must be rubbed up with a little water to the thickness of cream, and applied to the surface of a polished stone. An impression is taken in the common way from a drawing, and passed through the press, taking care to mark, by means of this impression, two points in the margin corresponding on each of the stones. The artist having thus on the second stone an impression from the first drawing to guide him, scrapes away the parts which he wishes to remain white in the finished impression. The stone must now be etched with acid stronger than the common etching water, having one part of acid to twenty of water. The whole is then washed off with turpentine.

This plan has been very much followed at Munich. It is generally used to print a middle tint from the second stone. The black impression being given from the first stone, a flat transparent brownish tint is given from the second, and the white lights are where the paper is left untouched. The dots are necessary to regulate the placing of the paper on the corresponding parts of the two stones.

The coloured inks for the tints are differently made, according to the tint required, but the varnishes alone make very good light browns.

The paper for Lithographic Printing should not be so damp as for Copperplate Printing.

8. Different manners of Lithography.

Besides the manners already described of drawing with ink and chalk, Lithography is practised in various other ways.

Transfers.

The most useful of these is the transfer, before Transfers. alluded to in speaking of the inks, as it saves the labour and inconvenience of writing backwards. This is performed by writing with the composition ink on a prepared paper, and then transferring the writing to a stone, by passing it through the press.

The paper is prepared as follows. A paste is made by dissolving, with heat, glue or starch in water till its consistency is such as to fix like a thin jelly when cold. It must then be mixed with gamboge and a little alum, in the following proportions:

Glue,	6 parts.
Gamboge,	1 do.
Alum,	½ do.

These must be mixed together over a fire, and applied while lukewarm in a thin coating on one side of a sheet of soft or unsized paper, which, when dry, must be rubbed over with a little powdered gum-sandarac. The writing is to be made with the fatter sort of ink on the prepared side.

When the transfer is to be made, a polished stone is warmed to about 130° Fahrenheit, and placed in the press. The paper is then carefully dampened at the back with a sponge, and placed between some sheets of soft paper. It is next placed on the stone with the writing towards it, and passed through the press as in printing an impression. This must be repeated four or five times without raising the leather cover of the bed of the press; beginning with a slight pressure at first, and increasing it every time. The press is now to be opened and the paper taken off, when the writing will appear to have come off the paper on the stone. If necessary, the paper may be a little dampened, to raise it from the stone, but it should be done with care.

When the stone is quite cold, it is etched and prepared for printing in the usual manner.

This mode is of great use for circular letters and written forms, but does not do so well for works of art, as the lines lose their sharpness by spreading a little at the edges, from the warmth of the stone. To obviate this, Senefelder has proposed a fatter ink, which may be taken off on a cold stone.

Imitation of Wood Cuts.

Imitation of Wood Cuts. This is a very easy mode, though not much practiced. A polished stone is covered all over with lithographic ink, and the parts which are to be left white are scraped away with a steel point. Very fine lines are most easily obtained by putting them in with a hair pencil. The stone is etched as before described.

Etchings on Stone.

Lithographic Etchings. A polished stone is prepared for this mode by washing it with diluted acid as weak as the water used for etching a drawing; and after that is washed off, and the stone is dry, it is to be covered with weak gum-water and a little lamp-black. This forms a coating to the stone, and the artist works on it with an etching needle, as in etching on copper. The lines he traces appear white, but look stronger than they will appear afterwards. The stone should be a little warmed, for the needle to work freely through the coating, and care must be taken not to breathe upon it. When the etching is finished, the surface is to be rubbed all over with linseed oil, which penetrates into the lines drawn by the needle. After this the coating is to be all washed off with water.

In this mode lines can be drawn as fine as on copperplate; it is, however, but little practised in England, though it is often employed in Germany.

The great distinction of Lithography from Engraving is, that it gives a fac-simile of an original drawing, which retains all the freedom and touch of the artist's own hand; while, on the contrary, an engraving must be a copy. This character in a lithographic print arises from the facility with which the drawing is produced; as the process is exactly that which the artist would follow in making a common drawing; and the farther advantage of a great saving of expence is derived from the same cause; for the drawing being made at once on the stone, the whole expence of the engraving is saved. This is particularly the case with drawings in chalk, or with outlines or slight works in ink; and thus the door is opened to the production of many works which could not otherwise be published on account of the expence of engraving.

The more finished drawings in ink, however, have not the same advantages, for the gradations in tint can be obtained only by the variations in the breadth and distance of the lines, which is the same principle as that on which the engraver works; and hence the labour is more nearly equal in the two methods.

It must be admitted, that there is much less difficulty, and consequently less education, required to draw the lines on the stone than to cut them on the copper, but no superiority is obtained in the impression; nor is there any other advantage attending the substitution of the stone for the copper than a saving of expence, which, from there being but few artists who have practised this mode of Lithography, is not considerable at the present time.

The number of impressions which can be taken from a chalk drawing will vary according to the fineness of the tints. A fine drawing will give 400 or 500; a strong one from 1000 to 1500.

Ink drawings and writings give considerably more than copperplates. The finest will give 6000 or 8000, and strong lines and writings many more. Upwards of 80,000 impressions have been taken at Munich from one writing of a Form for regimental returns.

If, however, we compare lithographic prints with fine line engravings, or more particularly with engravings in Mezzotinto, we shall observe, that the latter are more rich in their effect, and that the shadows have, in some places, more depth and brightness. This is in part obtained by cutting deeply into the copperplates, so as to lay on in the impression a mass of ink of a rich and deep black colour in the parts where it is wanted to increase the effect, and by this means the engraver extends the limits of his tints. Lithography will, perhaps, always remain inferior in this respect to line and mezzotinto engraving, as the principle on which it is founded is to print from the surface only. Some of the modes of engraving, such as soft ground etching and aquatint, are inferior to Lithography.

Such may be said to be the present state of Lithography; but it must be recollected, that it is as yet but a new art, and doubtless susceptible of great improvement. It is very much in want of the attention and practice of better artists, who would not only produce better performances with the present materials, but would also be able to point out in

what respects the materials might be improved. This want is more particularly felt in England, where Lithography has had to contend with many prejudices; partly from the opposition it has met with from en-

gravers, who consider it as a rival art; and partly from its having fallen into the hands of amateurs whose performances have brought it into a discredit, from which it is but now gradually recovering. (L. L. L.)

LONDON. Since the article LONDON in the Encyclopædia was written, the extension and improvement of the capital of the British Empire have proceeded with a rapidity equal, if not superior, to what has been witnessed at any former period.

In the city, or that part properly called London, the increase of buildings and their improvement have not proceeded with an equal pace to what have been exhibited in Westminster, and the other adjuncts, which form a large portion of the metropolis. The private dwellings have been, indeed, much improved and augmented, principally in the environs of Moorfields, and the site which was formerly occupied by the buildings of Bedlam Hospital are now (1821) about to be covered with good dwellings. The most extensive public building recently erected within the city is the new Custom-house, with one front to the river Thames. It is upon a much larger scale than the building destroyed by fire in 1812; its interior is far better arranged for the dispatch of business, and the simple elegance of its front is an addition to the beauty of the banks of the river. The clearing away the ancient and vulgar erections which covered the legal quays between the Custom-house and London Bridge will, when completed, add much to the beauty of that part of the banks of the Thames. The New Mint, on the north-east side of Towerhill, has been completed, and displays much simplicity and taste; but from being crowded by surrounding buildings, its full effect is lost. Though attention has been paid to the exterior of this institution, yet its great excellence consists in the curious, valuable, and accurate machinery by which its operations are effected; for a full account of which, we refer to the article COINAGE in this Supplement. The inconveniences of the situation, and of the scattered buildings which form the General Post-Office, have been long subjects of complaint, and at length measures have been taken for erecting a new Post-Office on a regular plan, in a more central part of the metropolis. A piece of ground situated between St Martin's le Grand and Forster Lane, at the north-west corner of Cheapside, has been selected for the purpose, and the houses and warehouses which stood upon it have been purchased and pulled down; by which a good access to Aldersgate Street, and the northern roads from the city, has been formed. The work is at present languishing on account of some differences betwixt the Corporation of London and the Postmaster-General. The estimate of the value of the ground and buildings to be purchased was made to be £240,000; but the actual expenses incurred on those purchases has already exceeded that sum; and £87,000 more is required to complete the payment for the whole of the ground and houses. An application was made to Parliament in July 1820, for the additional sum of £100,000. The committee to whom the petition was referred did not approve of the prayer for the grant, and, in consequence of this

state of affairs, the operation must remain suspended, till some new plan for supplying the pecuniary means is adopted by the Legislature. The Prison in the Poultry, called the Counter, has been removed. A new and more commodious edifice has been constructed near Cripplegate, capable of containing 250 delinquents, to which the prisoners have been removed, and the site of the ancient building is now covering with a spacious dissenting chapel. Among the public edifices of an inferior kind within the city that merit notice, may be mentioned the new house built on Moorfields for the London Literary Institution, to which its valuable library and apparatus have been removed. Near to it, on opposite corners of what is intended to form a new square, a very sumptuous Roman Catholic chapel, and an elegant chapel for a congregation of seceders from the Church of Scotland, have been built, the effect of which on the whole of that mass of buildings will be very good, when the plan is completed. The ancient building originally appropriated for a cloth market, known as Blackwell Hall, is now pulling down, and the corporation design building on the spot a range of offices for the Commissioners of Bankrupts, and for other purposes. One of the most striking improvements, because in Holborn, the broadest of all the streets in the city, is that which has been recently effected by removing the cumbrous front of Furnival's Inn, and replacing it with a more modern pile, covered with Bernasconi's composition, which has the appearance of Portland stone. Waterloo Bridge, Southwark Bridge, and Vauxhall Bridge, have all been completed, and opened for the public. As the particulars of their construction have been amply detailed in this work under the article BRIDGE, we must refer to it; only adding, that, from want of advantageous approaches, the tolls collected at Waterloo and Southwark Bridges are very inadequate to pay any interest on the capital that has been expended. The ruinous condition of London Bridge has been a subject of complaint for many years, and a Committee of the House of Commons has been appointed, to investigate and report on its present condition, and on the steps necessary to be taken to remove the inconveniences suffered as well by those who pass over as by the barges and boats that sail under it. Among the improvements to the facilities of the commerce of London must be noticed the docks of the East India Company (see the article DOCKS); the West India and London Docks, and the admirable commercial road leading to the two former, by which the goods from those deposits are conveyed to the warehouses in the city. Though not strictly speaking a part of London, yet the East Country Dock, and the Surry Canal, on the southern bank of the Thames, form a vast addition to the facilities of the metropolis, and are now in a complete state to receive shipping. Though the private dwelling-houses within the city

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