Egyptian blue is composed of sand, copper oxide, and soda, mixed together, ground finely, then moistened with water, tied up in a tiny bag the size of a walnut, put into a furnace and heated to the temperature of red-hot copper. This must be done in a small furnace, and the temperature must not be carried too high, or an ordinary green glass will result. The temperature must be just enough to fuse the copper, soda, and silica into what is called a frit, that is, the stage which immediately precedes the fusion of the ingredients which would result in glass. The ball of frit is taken out and pulverised, mixed with glue or gum arabic, and used as a paint. The depth of colour decreases if the paint is ground too finely. The green colour is either the natural green ore (malachite), or an oxide or artificial carbonate. The purple colour is manganese oxide. The red colour is simply earthy hæmatite or iron oxide. The black colour is either carbon or black oxide of iron, or both mixed together, or the black oxide of manganese. The yellow is plain yellow ochre, sometimes mixed with a little white. Grey is wood ash, mixed with lime white, or powdered gypsum. Lime white is merely ordinary lime which has got stale or slacked. [Illustration: A Winged Scarab and the four Genii.] ------------------------------------------------------------------------ CHAPTER VIII ALABASTER ALABASTER jars were used in the old days to contain pigments, ointment, kohl, and similar commodities. They were also placed in large numbers in the graves, hence the quantity that comes into the market. The price is moderate, from a few shillings to several pounds, and one would hardly have thought it worth while for the forgers to copy them; yet it is now regularly done. But there is something about the old alabaster jar or pot which makes it somewhat easier to distinguish from forgeries than is the case with scarabs. In the old pots there are certain irregularities of make, a kind of lumpiness from the way in which they were cut out. The pots are thin and drilled out to the bottom with the bow-drill, and the outsides are worn. Forgeries are made on the lathe, and are turned out regular in shape. They are thicker, heavier, and not drilled down to the bottom. The work on the interior is rough, and gives signs of having been hastily done. Some of the smaller pots are made in two halves, an upper and a lower, and joined by a cement about the middle. Sometimes old pots are recut or re-shaped, in order to give them a better appearance. The ones most difficult to tell from the originals are those made with the old bow-drill, for here comes in the slight irregularity of shape, and the work approaches much more nearly to that of the ancient Egyptians, as it is most probable that the originals were made in the same way.