BLUBBER, in Physiology and Commerce, the fat which invests the bodies of all large cetaceous fishes, serving to furnish an oil. The blubber lies imme diately under the skin, and over the muscular flesh. In the porpoise it is firm and full of fibres, and invests the body about an inch thick. In the whale its thickness is ordinarily 6 inches, but about the under lip it is found two or three feet thick. The quantity yielded by one of these animals ordinarily amounts to forty, or fifty, sometimes to eighty or more hundred weight. Its use in trade and manufactures is to furnish train-oil, which it does by boiling down. Formerly this was performed ashore in the countries where the whales were caught, but lately the fishers do not go ashore ; they bring the blubber home stowed in casks, and boil it down there. A machine expressly designed for expressing the oil from blubber is given under the word Om.
BLUE (Psussise). A very fine blue pigment, extensively used in the arts. It is composed of prussiate of iron, and the earth precipitated from alum or pure alumine. It is commonly obtained by calcining blood or other animal substances, as hoofs, horns, parings of leather, &c. by which a black coaly resi duum is obtained. Three parts of this are added, at intervals, to four parts of potash, kept in a state of fusion in a stout iron vessel, the mixture being con stantly stirred during the process. At first a reddish flame appears upon the surface of the mass ; this afterwards changes to a bluish tinge, denoting the formation of prussiate of potash, when the whole is to be removed as speedily as possible into a large vessel of boiling water, and stirred, to promote the dis solution of the prussiate of potash. After allowing the dregs to settle, the clear
liquor is drawn off, and fresh quantities of water boiled upon the residuum, until it ceases to impart much taste to the water ; and the whole of the liquor thus obtained being mixed together, a solution of alum and green vitriol is added, when a precipitate of Prussian blue is immediately formed, which is washed repeatedly to free it from the sulphate of potash ; after which it is put into bags and pressed, and then exposed to the air to dry, during which process it assumes a deeper colour, and acquires a hard stony consistence.
BLUE (Pownza or STONE), used in washing linen, is the same with smelt, either in the lump or powder. When the smalt is taken from the pot, it is thrown into a large vessel of cold water; this makes it more tractable, and more easily powdered. When examined after cooling, it is found to be mixed with a greyish matter resembling ashes, which must be separated by washing and then the blue substance being powdered and sifted through fine sieves, forms what is called powder blue.
BLUE (Sexon). The best Saxon blue may be prepared as follows :—mix 1 oz. of the best powdered indigo with 4 oz. of sulphuric acid in a glass bottle or =tress, and digest it for one hour in a water bath, shaking the mixture at different times; then add 12 oz. of water to it, stir the whole well, and when cold, filter it.