Gun powder

A well-known explosive, consisting of an intimate mixture of nitre, charcoal and sulphur. In the manufacture of gunpowder the ingredients selected must be perfectly pure, and they must be reduced to powder separately. They are then roughly mixed, sprinkled with water, and formed into a cake, which is after¬ wards broken up, granulated, and separated into cla es by sieves of different sizes of mesh. The violence of the explosive power of the substance is due to the sudden evolution of large quantities of gas. Gunpowder is supposed to have been in the seventh century by the Byzantine emperors in the defence of Constant i¬ nople. [Fr., from Lgrunnire, to grunt.] A kind of marine fish, supposed to make a grunting noise when taken out of water by the vibra¬ tion of the muscles of its air bladder. It has a large and spiny head, with mail ed cheeks and large eyes. Some gurnards are highly esteemed for food. The flying gurnard is found in the Atlantic, and is able to fly like the flying-fish. It has large pectoral fins filled with nerves, by the aid of which smaller animals are detected. Thus they serve as food-providers.