Mr. W. Simpson's Experiments With Pigments

Some washes of water-colour, of thirty-one different kinds, were made upon cards by the late Mr. W. Simpson. He so cut the cards as to divide each coloured strip in half; one section was preserved in darkness, the other was exposed in an eastern aspect on the shutter of a house in London for fifteen years, but the sun did not shine upon the specimens after ten o'clock in the morning. As they were not tightly framed, the cards became a good deal discoloured by the absorption of noxious vapours and dirt. The results were:

It will be noted that the above results are for the most part in agreement with those recorded by other experimenters; the chief exceptions are marked with a star. Vermilion is usually blackened, but it is possible that the sample employed in these experiments was the less changeable native form or cinnabar. The Vandyke brown, too, was probably the earthy rather than the bituminous variety; the slightness of the change recorded for madder brown and sepia, and the absence of any alteration on the part of bistre, are less easy of explanation. The madder pigments seem to have stood more than usually well, but they often exhibit large differences of stability. Nor must it be forgotten, in assigning values to the above results, that this trial of fifteen years' exposure was not of the severest kind. Although, on the one hand, there was the imperfect exclusion of an injurious London atmosphere, on the other hand, the energy of the solar radiation was much reduced by the prevalent condition of the smoky air, while the intermittent and capricious sunshine of the Metropolis never fell on the trial cards after ten a.m.

The late Mr. R. H. Soden-Smith kindly placed at my disposal a large number of specimens of old water-colour cakes and of powder colours intended for oil-painting. One set consists now of eleven cakes or fragments of cakes (in their original box) bought about the year 1815 of Newman, in Soho Square. This set is peculiarly interesting as the colours, which all bear the name of the maker and his device, represent those used by many of the best English water-colour painters during the first quarter of the nineteenth century. The cakes are: Indian yellow, raw sienna, raw umber, burnt sienna, burnt umber, vermilion, carmine, burnt carmine, pink madder, ultramarine, indigo; neutral tint and sepia are missing. On comparing the hues of the first nine of these paints and of the indigo with the hues of the corresponding cake-colours as sold by the same house in 1886, no appreciable differences were detected save in the case of the raw umber. Here the pigment of 1815 showed a more beautiful nuance than that of 1886. On making comparative tests of the stability, under exposure to sunshine, of the two sets of pigments, the results were found to be practically identical.

One cannot, therefore, claim for the water-colour paints in use one hundred years ago a degree of permanence greater than that possessed by their representatives of to-day.