If you enter any great lithographer's workshop to-day, like that of the Dangerfield Company at St. Albans, you will notice huge slabs of stone, two or three inches thick, ranging in size from that of a large bedstead to that of a small book. All these stones may be said to come from one place--Solenhofen, in the district of Monheim. At the Dangerfield Company's works the writer seemed to be passing through a miniature quarry, or through a tombstone warehouse. The stones arrive at the works in their rough condition. They are prepared for use by being ground face to face with sand and water. The broad principles of lithography consist, of course, in the strong adhesion of greasy substances to calcareous stone, the affinity of one greasy body for another, and the antipathy of such bodies to water. When water is applied to the surface of the stone it remains only on such portions as are not covered with grease, so that, if a roller charged with greasy ink be passed over the stone, the ink will only adhere to the greasy portions, while the moist parts will resist the ink and remain clean. In consequence, when a sheet of paper is pressed upon the stone, it only receives an impression in ink from the greasy line. This is the whole theory of lithography. And now comes in the task of the expert colour-master. There has been growing up of late years a class of experts in colour for whom the entire National Gallery is only a collection of tints on canvas more or less adroitly combined. These men are master-lithographers. For them the most divine creations of Raphael, Titian, Claude, and Turner are workmanlike colour-combinations, which it is their business to analyze and resolve into their separate constituents. To-day the dead walls and hoardings of the kingdom are covered with wonderful posters and the shop windows lined with gorgeous lithographs evolved by men whose chromatic perception is so acute that they can tell you at a glance what the great Turner himself did not know: how many colours go to the making of one of Turner's pictures. [Illustration: THE ARTISTS' ROOM AT THE DANGERFIELD COMPANY'S WORKS, SHOWING THE LITHOGRAPHIC STONES. _From a Photo. by_] [_the Dangerfield Co._ ] [Illustration: FIRST STONE--LIGHT YELLOW.] [Illustration: THIRD STONE--LIGHTEST BLUE.] There are very few artists who can say exactly how their colour-effects were produced, or precisely what pigments were employed to attain certain tones. They work away, slowly painting and repainting until the end desired is reached. [Illustration: SECOND STONE--DARK YELLOW.] [Illustration: FOURTH STONE--LIGHT FLESH TINT.] "We have master-lithographers in our employ," said Mr. Adolphe Tuck to the writer, "who can tell almost at a glance how many colours and shades go to the making of any given picture, no matter how complex."