(Gr. ni0os, a stone, and ypa-0eiv, to write), a method of producing printed copies of a writing or drawing on stone without the usual process of engraving. It was invented about 1796-'8, in Munich, by Aloys Sene-felder. As originally proposed by him, it was merely an etching in relief upon stone, a process which had long before been practised both upon stone and metal, although he was probably ignorant of the fact. As early as 1728 Dufay, a member of the French academy, described and practised a method of etching upon stone. He made a drawing with varnish, and used an acid to eat down the unprotected parts of the stone, leaving the lines in relief, and is said to have produced some exquisite work. About 1788 William Blake, the English painter, invented (or as he believed was spiritually taught) a similar process, only he used plates of copper, and in this manner produced his most famous works. Scnefelder's use of stone was wholly accidental. Being, like Blake, too poor to pay for printing his works, he endeavored to devise some means of doing this him-self from plates etched in relief, and to avoid expense he used smooth slabs of stone instead of plates of copper.

Being ignorant of the composition of the varnish used by engravers for their etching ground, he invented a kind of crayon composed of wax and tallow. One day his mother wished him to write out a list of clothes to be sent to the laundress. Paper and ink not being at hand, he wrote the list upon a stone with his crayon. When he was about to clean off the stone it occurred to him, as it had to Dufay, that the body of the stone could be eaten down by aquafortis, leaving the lines in relief, so that impressions could be taken in the usual manner. His experiments in this direction were partially successful, although less so than those of Blake. In 1798 he thought of the availability of the chemical principle which is the foundation of the art of lithography properly so called, namely, the mutual repulsion between oily substances and water. - The material upon which the drawing is usually made is an argillaceous limestone. Stones more or less adapted for the purpose occur in various parts of Europe and America; but the best are found in the quarries of So-lenhofen in Bavaria, and these are almost exclusively used, being exported to all parts of the world where lithography is practised.

The rock belongs to the upper oolite, is very closely grained, and is evidently formed from the finest sediments, the color varying from a light buff to a pearl gray. The stones, being quarried in mass, are split or sawn into slabs two or three inches in thickness and of any required size. To prepare them for use, they are ground to a perfectly uniform face and polished. If the drawing is to be in crayon, they are "grained"by rubbing two together, with the intervention of fine sand, the graining being finer or coarser according to the nature of the work to be produced. If the drawing is to be in ink, the surface is left polished. The crayons are composed mainly of tallow, wax, hard soap, and shell lac, colored with lamp black; other ingredients being sometimes added. The mixture is thoroughly incorporated in a closed vessel over a fire, and then moulded into the usual crayon form. Crayons, technically called "chalk," are required of different degrees of hardness; an increase of tallow makes them softer, of shell lac harder. With these crayons the drawing is made upon the stone precisely as upon paper.

For pen-and-ink drawings a piece of the chalk is rubbed down with water upon a marble or porcelain slab, so as to form a liquid ink, which is applied with a fine pen or a camel's hair pencil. Both methods are frequently used in the same drawing, the fine strokes and sharp outlines being made with a pen, the coarser ones with crayons, while broad masses and tints are washed in with the pencil. But owing to the presence of the alkali of the soap, the chalk is soluble in water, and the drawing can be washed off with a moistened sponge. Diluted nitric or hydrochloric acid is therefore poured over the stone; the acid unites with and neutralizes the alkali, leaving the remainder of the chalk insoluble in water. The acid attacks the uncovered portions of the stone, rendering them more porous and more capable of absorbing water, and also eats it down, leaving the lines in slight relief, and thus facilitates the process of printing. The stone is next washed with pure water and afterward with gum water; the object of the latter is to prevent the coloring matter from spreading under the pressure to which the stone is to be subjected in printing, and to retain the acid that adheres to the greasy substance, the quality of which it is designed to change.

Being then rolled over with printers' ink, it is ready for printing, although it is sometimes necessary to lay it aside for a day or two in order that the chalk may become thoroughly hardened. Sometimes the drawing is made upon transfer paper, which is merely paper coated on one side with a solution of gum, starch, and alum; thus the drawing is not directly upon the surface of the paper, but upon the preparation with which it is covered. The paper is then laid upon the stone, and pressure being applied, the ink adheres to the stone, for which it has a strong affinity. The back of the paper being moistened, the gum is loosened, when the sheet is readily removed, and the remaining gum is washed off with water. The stone is then treated precisely as though the drawing had been originally made upon it. The transfer process is also used to multiply copies for printing of the original drawing, and also to produce copies of engravings to be printed lithographically. For this purpose an impression from the original plate is taken upon transfer paper in transfer ink, which is composed mainly of the same ingredients as the chalk, only reduced to a semifluid state by oil or some other liquid. The number of copies which can be taken from a single lithographic drawing varies greatly.

A fine crayon drawing will give from 500 to 3,000 good impressions; an ink drawing about twice as many; while from drawings produced by the photolithographic process, described further on, as many as 30,000 have been obtained. It is customary to make one or more transfers, which can be substituted for the original drawing when worn out. Plates of metal, especially of zinc, are sometimes used instead of stone, and in the same manner; but stone is generally preferred. Stone is also frequently employed as a material upon which to engrave, in the same manner as upon a copper plate, only the lines are cut with a diamond point instead of a graver. For maps and plans this succeeds very well, the work being nearly as good, and the cost much less. Engraving upon stone, however, does not properly come under the head of lithography, the printing being performed as with copper plates, and not in the manner now to be described. - Lithographic printing is a process partly chemical and partly mechanical. The ink used is the ordinary printer's ink, composed essentially of linseed oil and lamp black, in a semi-fluid state, although other ingredients are usually added. (See Ink.) The lithographic hand press consists of a roller revolving upon its pivots in an upright frame, with a bed beneath it, moved back and forward by a winch.

The stone is firmly secured upon the bed, and a moistened sponge is passed over it; the water is repelled from the greasy lines of the drawing, but wets the uncovered parts of the stone. The ink is applied by means of the usual printer's roller; it adheres to the greasy lines, and is repelled from the wet stone. The bed is then pulled under the roller, which is adjusted so as to give a heavy pressure. The ink is thus transferred to the paper, which also absorbs the moisture of the stone. These successive operations of wetting, inking, and pulling must be repeated for each impression. If the drawing is a large one, not more than 75 or 100 impressions a day can be taken upon the hand press; if the drawing is small, seven or eight times as many. Power presses have been constructed within a few years capable of working off 1,000 sheets an hour of any size. The principle, however, is the same as that of the hand press. The quality of the paper is a matter that requires attention. If it contain any gritty substances, it will soon act upon the stone; plaster in its composition soon causes the lines to be clogged; and alum attacks the gum and ruins the drawing.

The printer should be able to appreciate the character of the work in hand, for upon his manner of applying the ink the general tone of the impressions may in great part depend. Their perfection is also in part due to the condition of the paper as to proper amount of moisture, and to the manner of regulating the press. - Lithography was introduced into Vienna in 1802, into Rome and London in 1807, and into Paris in 1814. Everywhere it met with great favor, and especially in Paris. Artists of distinction practised and aided to perfect it; and it was fashionable for the nobility to design on stone. Lemercier cultivated the art with the most distinguished and long continued success. He invented the autolithographic or transfer paper; and at the Paris exhibition of 1855 the medal of honor was awarded to Lemercier, who was then conducting a large establishment containing more than 100 presses and employing about 200 workmen. Count de Lasteyrie invented the method of facsimile printing, applicable to obtaining copies of characters that cannot easily be brought into ordinary typography, and also to maps in which all the details are lithographic, while the names of places are first produced upon the paper by ordinary printing.

Engelmann by his knowledge of chemistry was able to give a great impulse to the art of lithographic printing in colors, or chromo-lithography. Full treatises upon lithography were published in 1819 by Count Raucourt and Senefelder. In England its productions have been of a high order, especially in landscapes; and the establishment of the Ackermanns in London was long famous for the fine specimens it furnished in this department, including the productions of Hughe, Ward, Westall, Harding, Lane, and others. The art was introduced in America in 1821, and was practised by Messrs. Barnet and Doolittle in New York. There is a favorable notice of it, with some of the earliest specimens, in the "American Journal of Science" for 1822. For many years, owing to the want of artists, it made little progress here, except for commercial purposes and the production of cheap prints; but within the last few years many works of much merit, especially portraits, have been produced by Sarony and others.

Chromo-Lithography

Chromo-Lithography is the art of producing by lithography works in which various colors are printed in a single picture. It is much used in various branches of ornamental work, and has been successfully employed in the production of pictures which are almost facsimiles of paintings and colored drawings. Each different color is printed separately, from a stone which contains only the one color. Very frequently 10 or 15 separate stones are employed, and in some very elaborate prints as many as 30 or 40, some colors being printed over others to produce variations of tint and shading. In the first place a drawing is made which contains the general outlines of the position of the different colors. On the second and third stones the general effect of the drawing is worked in; these are printed in neutral colors, as a pearl gray or faint sepia. Each succeeding stone is charged with its own special tint, brown, blue, green, or yellow, as the case may be; and the last one contains the sharp dark touches, whether of shade or outline, which give character and expression to the whole. Upon the skill with which these colors are arranged, and upon the accuracy with which each falls exactly into its proper place, depend the value of the whole work.

The misplacement of a single color to the extent of the fiftieth part of an inch might mar the whole. This involves the necessity of the utmost accuracy in the drawing upon each stone, and also in the placing of the paper in its exact place at each impression. The difficulty of this last is much increased by the fact that the sheet of paper must be dampened at each impression, whereby it expands perceptibly, and dried, when it contracts. If these successive dampenings be unequal, some of the colors will not fall in their right places. Finally, if an oil painting upon canvas is to be reproduced, an additional impression is given from a plate upon which are embossed lines representing the threads of the canvas. The print is then varnished or glazed, like an oil painting. Many "chromos" thus produced can hardly be distinguished from the original pictures from which they are copied. Chromo-lithography has been brought to great perfection in London, Paris, and Vienna. In the United States Mr. Louis Prang of Boston has within a few years executed many works not excelled by any produced in Europe. It is said that the first successful attempts to produce chromo-lithographic portraits, in which the effects of the painter were closely imitated, was made about 1860 by Mr. E. 0. Middleton of Cincinnati, Ohio. He produced previous to 1866 a series entitled "Middleton's National Oil Portraits," several of which are admirable specimens of the art.

Photo-Lithography

Photo-Lithographyis the art of producing lithographic drawings by the action of light. About 1813 Joseph Nicephore Niepce began his experiments for the production of permanent photographic pictures. These are the earliest on record, though not published till many years afterward. He used asphaltum as the substance sensitive to light, dissolving it in essential oil of lavender, and applying it as a thin varnish to metallic plates. After long exposure in the camera or under a cliche of some sort, the asphaltum became insoluble in the parts affected by light, and the picture was developed by dissolving away the unaffected portions. Undoubtedly Niepce had in view not only the production of a picture, but also the subsequent etching of the surface supporting his photograph, so as to yield engraved plates from which copies could be printed in the press. In 1839 his method was superseded by that of Daguerre, with whom he had associated himself; but his discovery of the sensitiveness of asphaltum formed the basis of the first photo-lithographic process deserving the name.

This invention was made by Lemercier, Barreswill, and Lerebours of Paris, and patented in France in 1852. They proceeded by making a solution of asphaltum in ether, coating a clean lithographic stone with this varnish, and exposing under a negative the dried surface so prepared. When the light had sufficiently acted through the transparent parts of the latter, the stone was washed with ether in abundance, whereby the unchanged and still soluble portions of the coating were removed, and the stone was gummed, rolled up with ink, and etched in the manner practised by lithographers. This invention was based essentially on the discovery that the altered mineral pitch had an affinity for the greasy ink on the lithographer's roller, and this was applied to the production of designs on stone. The process gave crude results; but it was the first of a series of six photo-lithographic methods, each of which must be regarded as typical, and therefore worthy of description in the present article. - M. Poitevin of Paris patented in December, 1855, a process for producing printable designs on stone.

This was to a certain extent based on Mungo Ponton's original and fundamental discovery in 1839, that a sheet of paper sensitized with bichromate of potash applied in solution, and dried in the dark, was acted upon by light, giving a negative brownish picture, which, after exposure under an intercepting screen, resisted the solvent action of water. Becquerel had subsequently shown that the sizing of the paper played an important part in this phenomenon; but Poitevin in 1855 was the first to discover and utilize the remarkable property possessed by organic matter altered by the action of light in the presence of bichromate of potash, which forms the foundation of most of the photomechanical printing processes now in use; namely, that of repelling water and attracting greasy bodies, such as lithographic ink. To accomplish his purpose he coated the lithographic stone with a solution of bichromate of potash and albumen. After exposure under a negative, he applied moisture and ink followed by etching, in the manner practised by lithographers, thereby obtaining an inky picture on the parts exposed to light.

This process is interesting, although the results were far from satisfactory, inasmuch as the printing took place, not from a picture on the stone itself, but separated from it by a film of altered organic matter; a circumstance which was not recognized by Poitevin, but was made use of many years later by Tessie du Motay, Albert, Edwards, and others, in their collographic processes, which are of so much importance at the present day. Joseph Dixon, late of Jersey City, published the essential features of this process in 1854; but his experiments were of a somewhat incomplete nature, and not sufficient to displace the claims of Poitevin. Messrs. Cutting and Bradford of Boston, Mass., patented a photo-lithographic process in March, 1858. They sensitized the stone much as Poitevin did, using bichromate of potash, gum arabic, and a little sugar. They exposed it however under a transparent positive, and washing the stone with a solution of soap, succeeded in making those parts of it take the ink which were unacted on by light; the altered gum protecting the other places from the soap water. In this case the lithographic work was actually on or in the stone. A suitable etching removed the altered gum after rolling up. - M. Asser of Amsterdam was the first to suggest a transfer process.

This invention was made early in 1859, but not published till November. His method consisted in sensitizing a sheet of unsized paper, or one slightly sized with starch, with bichromate of potash; exposing the same under a negative; washing the resulting print with water; drying and heating it strongly upon a hot plate; and finally again moistening and rolling up with transfer ink. The transfer sheet so prepared gave an inky positive picture, corresponding with greater or less fidelity to the lights and shades of the negative. After completion it was transferred to stone, which was then etched in the usual manner and printed. This process, like all the preceding, never gave results of commercial value. - J. W. Osborne, then of Melbourne, Australia, in August, 1859, invented the photo-lithographic process which bears his name. He prepares a sheet of paper by coating one side with a viscid solution, consisting of a mixture of albumen, gelatine, and bichromate of potash; this, after being dried in the dark, is exposed under a negative of the original to be reproduced. The photographic positive picture thus obtained is inked all over while dry by pulling it through the press face down, in contact with a lithographic stone to which an even coating of transfer ink has been applied.

When the sheet is removed from the stone, the adhesive ink covers its surface, and nearly conceals the underlying photographic picture below it. This sheet is next placed floating on hot water, with the inked side upward; the moisture and heat together effect a coagulation of the albumen in the compound organic film, while the gelatine portion of the same gelatinizes and swells. The sheet is now lifted from the water, laid flat upon a slab, and friction applied to its inked surface by means of a wet sponge. The superfluous ink not needed to form the transferable picture is hereby removed; the sheet is flooded with abundance of warm water, dried, damped again slightly, and transferred to stone by simply inverting it thereon and pulling it through the press in the usual way. When removed the ink on the surface of the transfer sheet will be found to have passed over to the stone, which is then rolled up and etched, after which it is ready for the printer. In this process the albumen plays an important part; its insolubility after coagulation prevents the undermining of the finer details by the solvent action of the water, and it also sticks the sheet to the surface of the stone during the operation of transferring, thereby preventing any shift and consequent doubling of the work.

This process is chiefly adapted for copying line engravings, drawings, manuscripts, etc.; and this is also true of all analogous methods. It was adopted by the government of Victoria in September, 1859, for copying and publishing maps and plans; and since that time many thousand originals have been reproduced, being at present almost the only means employed there. This photo-lithographic process was the first which proved of real practical value. In 1865 the American photo-lithographic company of New York was organized, and has since worked this process with unvarying success. The drawings of the patent office for several years, and those of other governmental bureaus, have been executed by its means, whereby a great saving in cost and innumerable advantages in promptness and accuracy have been secured. - In August, 1861, Mr. Hannaford of London suggested a photo-lithographic method, which he never reduced to practice, but which M. Toovey of Brussels subsequently patented. Although this process has not come into general use, it must be regarded as essentially typical in its nature. Mr. Hannaford recommended the preparation of a sheet of paper with bichromate of potash and gum, its exposure under a negative, and its transfer while damp, without inking, to the stone.

The consequence would be the passing over to the latter of more or less gum from the unexposed and unaltered parts, whereby the stone on such places would be incapacitated for receiving ink. If we now attempt to roll up the transferred surface with ink, we shall find the latter to adhere only to the clean parts of the stone, forming there the lithographic picture. - In addition to the six essentially different processes which have been described, there are numerous others based upon them, which it is unnecessary to particularize here. - As early as 1841 the late Mr. Joseph Dixon of Jersey City, and Mr. Lewis, a lithographer of Dublin, Ireland, each made attempts at the production of pictures on stone from which impressions could be printed. Mr. Dixon used bichromate and gum, much as Poitevin did. Mr. Lewis prepared a card surface with hard transparent ink, gave the same a thin coating of metallic silver, and then, proceeding as in the daguerreotype process, managed to expose certain portions of the underlying ink, which he then transferred to stone.

The experiments of both these gentlemen were exceedingly limited, and the evidence respecting them is derived from their own later statements only, no specimens or contemporaneous description being extant; but when we remember that the announcements of Fox Talbot's and Daguerre's inventions were only made two years before the date claimed by them, their assertions, which there is no reason to doubt, are of the highest interest. - In 1873 the Graphic company was formed in New York, for the purpose of conducting the business of photo-lithography on a large scale. They established a daily illustrated newspaper, "The Graphic," one side of which, containing four large pages, is printed in lithograph, the illustrations being produced by photo-lithography, and the other side from type in the usual manner. They profess to have made many improvements in the processes employed, the essential features of which they retain as a secret. By their processes they are able to produce upon stone a photo-lithographic copy of any engraving or drawing in less than half an hour, although two or three hours is the usual time. - At the present day photo-lithography is one of the necessities of civilization, and there are few cities of importance where it is not practised, Its results have done much to popularize the graphic arts, and to bring admirable copies of engravings, maps, and drawings within the reach of all. (See Photography.)