II. BLUES. 1. Prussian blue is a colour very apt to bind, and is rendered soft with more difficulty than carmine and lake. The same method of preparation is to be followed with this as directed with respect to lake, only it is necessary to grind a larger quantity of the pure colour, as it is chiefly used for painting draperies. The different tints may be made according to necessity, or the fancy of the painter. 2. Blue-verditer is a colour naturally gritty, and therefore it is necessary to wash it well. Its particles are so coarse as to require some binding matter to unite them, otherwise the crayons will never adhere together. To accomplish this, take a quantity sufficient to form two or three crayons, to which add a piece of flaked plaster of Paris about the size of a pea; mix these well together, and form the crayons upon the chalk. This blue is extremely brilliant, and will be of great use in heightening draperies, &c. The tints must be formed with whiting as directed in the former instances, and are highly serviceable for painting flesh, to produce those pearly tints so beautiful in crayon-pictures. It is not necessary to mix the compounds with spirits, as clear water will be sufficient.