The moulds in which the cakes are made must be very carefully worked in metal, so that the description and trade mark print clearly upon the cakes. The cakes should be dried at the ordinary temperature or but little higher. They are placed upon smooth boards, and care is taken that the temperature of the drying room remains uniform, which is the condition requisite for the production of the fewest cracks. When it is intended to place on the market only faultless and well-stamped cakes they must be sorted when dry, and the cracked ones rejected; these can be worked up in the next operation. The dry cakes are given a good appearance by coating them with a weak solution of gum, and then drying. According to the price at which these colours are to be sold the cakes are given a different character. The finest colours are generally made into larger cakes and packed in handsome boxes, whilst ordinary cheap colours are made into small lumps or circular plates, flat on one side and somewhat convex on the other, and packed in boxes of soft wood. =Moist Water Colours.=—Instead of grinding water colours with gum Arabic or tragacanth and bringing them on the market in the dry state, they may also be sold in a condition resembling that of oil paints. This may be accomplished by using very viscid glucose syrup instead of gum Arabic, and grinding the pigments in this exactly as in oil. Glucose is very hygroscopic, the colours prepared with it remain moist, and may be spread out upon the palette like oil colours. It is then only necessary to wet the brush in water and mix the mass with it in order to obtain colour of the proper consistency. Moist water colours have also been known as ”honey colours,” since this mixture of sugars was formerly used for their preparation; it also is hygroscopic. Honey is no longer used; the much cheaper glucose answers the same purpose. On account of their semi-fluid nature, moist water colours are put up in tubes just as oil colours. They are thus rather dear, but are little used. CHAPTER LXVII. CRAYONS. Crayons are coloured pencils by which pictures may be, so to speak, ”dry painted”. At present this method of painting is little used, though it was in vogue in the last century, but coloured pencils, especially blue and red, are much used for writing. Crayons are now used in a very convenient form, being generally made in the same manner as lead pencils. The coloured mixture from which the crayon is made is produced in the form of a paste containing a soft, finely ground mineral, well mixed with the colouring matter and an amount of binding medium just sufficient to hold the powders together.