The adulteration of pigments, which we have in some instances found practised to a large extent abroad, is comparatively unfrequent in our own country, so far at least as regards the superior class of colours employed by artists. As a rule, such colours when manufactured in England may be fairly assumed to be genuine; and certainly the respectable colourmen of the present day are not in the habit of sophisticating them. We must bear testimony, indeed, to the zeal with which they purvey, regardless of necessary expense, the choicest and most perfect materials. This should be a matter of congratulation to the painter, who must of necessity rely on the faith and honesty of his colour-dealer; for if he were ever so good a chemist, it would be impossible for him to analyse each pigment before proceeding to use it. The fault must rest with himself, therefore, if, through a mistaken economy, he do not frequent the best houses and pay the best prices. Of a surety, the colours of the artist are not among those things in which quality can, or should, be sacrificed to cheapness.
2. BLANC D'ARGENT, OR SILVER WHITE.
These are false appellations of a white lead, called also French white. It is brought from Paris in the form of drops, is exquisitely white, but of less body than flake white, and has all the properties of the best white leads. Being subject to the same changes, it is unfit for general use as a water-colour, though good in oil or varnish.
3. CREMNITZ WHITE,
Known likewise as Kremnitz, Crems, or Krems white, is a carbonate of lead which derives its names from Kremnitz in Hungary, or Crems or Krems in Austria. It is also called Vienna white, being brought from Vienna in cakes of a cubical form. Cremnitz white is the brightest white that is used in oil: it possesses rather less body than flake white, because the particles are finer. When newly prepared, it gives out a strong smell of vinegar.
4. FLAKE WHITE,
Called, when levigated, Body white, is an English white lead in the form of scales or plates, sometimes grey on the surface. It takes its name from its figure, is occasionally equal to Crems white in colour, and generally surpasses in body all other white leads. In composition, it is a mixture of protocarbonate and hydrated oxide of lead, the latter decreasing the opacity of the product according to the greater proportion in which it is present.
5. FLEMISH WHITE, OR SULPHATE OF LEAD
Is an exceedingly white precipitate from any solution of lead by sulphuric acid, much resembling the blanc d'argent. It is inferior, however, both in body and permanence to the ordinary carbonate. Hence, white lead which has more or less been converted by sulphuretted hydrogen into sulphide, and again been converted into sulphate by oxidation, with a view to restoring its colour, becomes peculiarly liable to the influence of impure air.