"Aureolin, in combination with Cobalt and Sepia, or Rose Madder, gives most agreeable and delicate tints for distant trees, when under the influence of a soft light, or hazy state of the atmosphere. Having most impartially and diligently tested the qualities of the Aureolin, I can and do most conscientiously recommend its adoption by all who practise water-colour painting." The foregoing sufficiently proves the value of aureolin in water, and similar flattering notices have been given of the colour in oil. Both in a chemical and artistic sense, therefore, this new primitive yellow merits the highest regard, and justly claims a foremost place among that little band of pigments which are without fear and without reproach. For mural decoration, aureolin is admirably adapted, but it cannot be used in enamel, the colour being destroyed by great heat. CADMIUM YELLOWS. Of these there are three tints, _Deep_, a so-called _Pale_, and _Lemon_. 21. DEEP CADMIUM. Cadmium Yellow is comparatively a recent introduction, the metal itself not having been discovered till 1818. The cadmium yellows of commerce are (the chromate excepted) all sulphides, and therefore not affected by impure air. Until lately, they were not manufactured in England but imported from abroad, and as a rule were sadly doctored. We have found in them a large proportion of orpiment, chromate of lead, &c., together with quantities of soluble salt, extracted by boiling water. Owing to careless preparation, there was also present an unnecessary amount of dirt, which interfered as much with the purity of the colour, as sophistication lessened its stability. For these reasons, doubtless, cadmium yellows got to be regarded by some with disfavour and suspicion; and it may fairly be said that they did not attain their present popularity, until they became an article of home produce. Deep cadmium yellow, if genuine, may without hesitation be declared permanent, both with respect to foul gas, and exposure to light or air. The variety under notice is of extreme depth, inclining to orange, glowing, lustrous, and brilliant. It is not very transparent, but wonderfully clear and bright, of great power, and the most richly toned yellow known. For draperies it is particularly adapted, and for gorgeous sunsets is invaluable. It works and washes well, readily throws all other yellows into the shade when used alone, and combines admirably with Chinese white for the light touches of bright clouds or mountains.