Gold and other metals have been melted, and even burnt; and potass, soda and lime have been reduced to their respective metallic states, by being made to form part of a galvanic circuit. When the pile is not in use, it should be taken down, which will preserve it from wear, and the plates will require to be cleansed occasionally, which may be easily done by diluted muriatic acid. 102. CONSTRUCTION OF THE OXY-HYDROGEN BLOW-PIPE.--This useful instrument consists of a cubical vessel, made of tin plate, being from ten to twenty inches in length, breadth and height. The inside is divided into four equal apartments, by two partitions, crossing each other in the centre. The two front apartments are covered at the top, and each of them have a tube fixed in the front side, near the top, with a stopcock. The other apartments are open at the top, and communicate with those in front, by a small aperture near the bottom of each. These apartments being all filled with water, those in front are filled, the one with oxygen, and the other with hydrogen gas, which is done by forcing the gases into them through the tubes in front, which causes the water to recede through the aperture at the bottom, and consequently, part of the water is forced over the top of the other apartments; or rather, may run off through small tubes, fixed for the purpose, near the top, similar to those in front. When the front apartments are filled with the gases, (which may be known by the bubbling in the others) the tubes are stopped, and two leaden pipes are fixed in them, the opposite ends of which, are so placed, that the two streams of gas, when expelled from the gas holders, may come in contact very near the ends of the pipes. When the tubes are open, the pressure of the water will expel the gases, and will consequently settle, and must be replenished, so as to keep the apartments nearly full. When the two streams of gas are ignited at the point of contact, a flame is produced of sufficient intensity to burn gold, silver, copper or tin, with a very brilliant combustion.