We may now pass on to some instructive examples preserved in the National Portrait Gallery:

Marc Gheeraedts (1561-1635)

No. 64. In this portrait, painted probably in 1614, while the vermilion has stood, the translucent reds appear to have faded and changed. The white sleeves of the dress are ornamented with small sprigs, which are now brown, and were probably originally painted in some vegetable yellow. The reddish pattern of conventional foliage on the cloak now clashes with the colour of the chair, the curtain, and the table; the hues of all or some of these parts must have altered.

Sir Peter Lely (1617-1680)

No. 509. A well-preserved picture in most respects, but it is probable that crimson-lake has been used for the satin dress, which is now a pinkish grey, and clashes with the flesh tints. This work was probably painted about 1669.

William Hogarth (1697-1764)

No. 289. This portrait of Hogarth, painted in 1758 by himself, affords some information as to the pigments he employed. He holds in his left hand a mahogany palette 'set' with eight colours. The first of these is white lead, and remains unchanged; so also is the second, vermilion; the third is a pale warm brown, precisely the hue of faded crimson lake; the fourth is now nearly black and undeterminable; the fifth is yellow ochre, slightly embrowned; the sixth is a pale yellow, well preserved - much like true Naples yellow; the seventh is a grey-blue, probably much changed; and the eighth and last a fair lavender blue colour. The seventh pigment may have been indigo, and the last possibly smalt. The cap on the artist's head has certainly faded in colour; probably it was painted with cochineal lake.

William Hoare, R.A. (1706-1792)

No. 112. This portrait of Alexander Pope, in coloured crayons on grey paper, shows the blues apparently intact.

Thomas Phillips, R.A. (1770-1845)

No. 269. This portrait of Faraday, painted in 1842, shows a large number of cracks, many of them wide. Where flake-white has been introduced somewhat freely, as in the face and hands, the shirt and collar, and the galvanic battery on the table, the paint has not lost its continuity.

John Partridge (1789-1872)

No 342. 'Meeting of the Royal Fine Arts Commission.' This picture was painted in 1846. Almost every part of it is very badly cracked through the use of bitumen, and perhaps also of much megilp. Even the shaded portions of the faces have not escaped, although the high lights have been preserved where the proportion of white lead present has been large.

Many instructive illustrations of the degrees of stability shown by pigments are furnished by examples in the Wallace Collection at Hertford House.

Philippe De Champaigne (1602-1674)

No. 119. This picture is remarkable not only for the perfection of its technique, but for the extraordinary state of conservation of all the pigments, which cover a wide range of colours, and include a transparent amber-yellow and a rose.

Sir Joshua Reynolds (1723-1792)

No. 47. Here the fatal asphaltum asserts itself, the background resembling a dissected map.

J. L. E. Meissonier (1815-1891)

No. 291. Generally the works of this careful painter are well preserved, but in this small example there are to be seen a few thin long cracks, which seem to have arisen in consequence of the premature application of varnish to the picture before the oil-paint was hard.

In Sir John Soane's Museum the two fine series of well-preserved oil-paintings by W. Hogarth (1697-1764) will repay careful study from the point of view now being considered.

The remaining works to which attention is now called are a few of the water-colour drawings shown in the Victoria and Albert Museum.

William Daniell, R.A. (1769-1837)

In one of the water-colours by this artist the blue and green elements have disappeared, save just in one little bit of smalt blue in a sailor's clothes. In another drawing the sky is now a mere dirty laboured stain.

William Green (1761-1823)

No. 685. An iron red has here become too prominent.

Samuel Howitt (1765-1822)

No. 3,019, 1876. Apparently well preserved, but, on further scrutiny, it seems that the ultramarine in the shaded parts of some of the rocks and trees stands out more prominently than it could have done originally.

Anne Frances Byrne (1775-1837)

No. 1,358, 1874.

In this fruit and flower piece the indigo in the sky has gone, while the yellow pigments and the red lakes have suffered greatly; the roses are blanched, and the purple grapes have lost their crimson element.

John James Chalon, R.A. (1778-1854)

No. 570. The 'River Scene in Devonshire,' painted in 1808, shows the shaded parts of the clouds pink, from the loss of indigo. The hills are now too pale for the trees dotted upon them, through the fading of sap-green and gamboge, which have been used in painting the grass. The shadows under the ripples of the water have greatly altered, from the change of indigo and other pigments; they now show dirty stains and elaborate brushwork.

No. 54, 1887, 'At Hampstead Heath,' by the same artist, is, on the other hand, a well-preserved drawing, which has been more recently acquired by the museum. The blues are particularly good, although the vegetable yellows may perhaps have faded somewhat in spite of the care which has been taken with the drawing.

John Cristall (1767-1821)

No. 142, 1890. This drawing seems to have kept its hues well, and affords a good example of the style of colouring of the period and school to which it belongs.

Jacob Xavery (Painted In 1757)

No. 15, 1872. This has faded woefully. The sickly peaches and spectral grapes proclaim the evanescence of crimson lake, gamboge, and indigo.

Mary Moser, R.A. (1744-1819)

No. 160, 1881. Very little is left of the original colour here; the 'roses and other flowers' are a complete wreck.

Francis Danby, A.R.A. (1793-1861)

No. 480. The blue in the sky unchanged, but the pigments which once modified its hue have fled.

John Varley (1778-1842)

No. 381. Hot iron reds show themselves in great force in clouds and elsewhere - even in the river; the modifying organic pigments with which they were mixed have nearly disappeared.

George Cattermole (1800-1868)

No. 503. The crimson lake seems to have faded from the face in this drawing. In No. 507, painted in 1850, we have a good illustration of the warm brownish hues produced by the deterioration of crimson lake.

Samuel Prout(1783-1852)

Nos. 1,473, 1869, and 3,056, 1876, afford examples of the stability of true ultramarine. The skies in both these drawings are now quite out of harmony with the architectural features, some of the pigments in which must have faded. These drawings should be compared with others by the same artist which hang beside them, and in which the blues of the skies, as well as some of the pigments in other parts, have faded. Here it may be convenient to remark upon the startling prominence of the skies, and sometimes of the blue distances, in many water-colour drawings. The first glance on entering a room in which such works are gathered reveals the permanence of ultramarine and cobalt blue, the latter pigment being, of course, of comparatively recent introduction. But the want of harmony in such drawings furnishes evidence at the same time of the decay of many other pigments - of liquorice and tobacco-juice, of yellow lake and brown pink, of indigo and rose pink.

William Henry Hunt (1790-1864)

No. 1,031, 1873. Some of the ruddy hue from the cheeks of the boy appears to have gone. In 1,525, 1869, some of the pink in the apple-blossom has faded; the primrose-flowers are greener and less yellow than they once were, probably from a change in lemon yellow. The hawthorn-blossom in 1,470, 1869, has lost the faint rosy blush that was once visible in some of the flowers - a delicate hue which I can distinctly recall.

The above examples, selected almost at random, must suffice. But I may point to a different kind of injury, from which water-colour drawings sometimes suffer, by citing the case of W. Delamotte's 'View of Christ Church, Oxford.' This seems to have been pasted on wood, and to have been stained in consequence; at least, it appears likely that the brown spots in the sky may be traced to the mount. A work by T. Barker (No. 134, 1878) and the 'Dieppe' of J. S. Cotman (No. 3,013, 1876) furnish additional examples of the same kind of damage.