Take the case of one of the most successful reproductions of one of the old masters, "The Madonna Ansidei," which hangs in the National Gallery. The colour-master of whom we have spoken quickly resolved this picture into eighteen colours, involving the use of eighteen lithographic stones, each printing a separate tint and being of itself almost a separate picture, until by repeated printings the whole masterpiece was gradually built up. This is the example of which we present illustrations in this article, and is the work of Mr. Adolphe Tuck. [Illustration: FIFTH STONE--DARK BROWN.] But what an eye for colour! What a gift for the realities and essentials of tone to be able, without any mixings of paint or other analytic experiments, to divine straight away just what colours are needed, and prepare stone after stone with the absolute certainty that the combination would produce such a result! [Illustration: SIXTH STONE--LIGHT BROWN.] [Illustration: SEVENTH STONE--LIGHT BLUE.] To illustrate the almost marvellous capability of the colour-expert in analyzing the colours of a picture submitted to him, one may mention that the late Sir Charles Eastlake, P.R.A., once ventured to assert that there were sixteen colours or shades visible in a picture by Van Dyck. The lithographic colour-expert declared there were only eleven. Accordingly an accurate copy was painted at the National Gallery of the picture, so accurate that it was difficult to discern a difference between the copy and the original. This was duly analyzed and placed on the stones, eleven in number, and the eleventh printing disclosed an exact facsimile of the copy, and therefore of the original. [Illustration: EIGHTH STONE--PINK.] [Illustration: NINTH STONE--MEDIUM GREY.] Sir Charles Eastlake acknowledged himself beaten, and readily paid tribute to the wonderful analytic powers of an artist, or, rather, of a scientist, who could not paint a picture but could tell just what a picture was made of. [Illustration: TENTH STONE--MEDIUM BLUE.] In the case of the Ansidei Madonna, the canvas was copied at the National Gallery under the eye of the Director. The first stage of reproduction was to transfer upon the stone a sort of yellowish-grey base or silhouette of the whole picture (No. 1). It will be noticed that the high lights are upon portions of St. John's and Mary's garments and the mitre of St. Nicholas. The picture on the next stone, which is to overlay the first, gives more detail.