A remarkable method of cutting metals has been developed in the use of the oxy-hydrogen and oxy-acetylene burners.

To a blow pipe used for heating is attached an additional tube through which a jet of oxygen is blown from a supply tank. The blow-pipe flame heats the metal to be cut, and when so heated, the small jet of oxygen directed against it burns a narrow cut along any path over which the flame may be directed. So readily do oxygen and red-hot metals unite, that such a burner is used to cut plates of metals, including steel armor, up to 9 inches thick. The width of the cut is not over 1/8 inch and the metal on each side of the cut is unchanged in grain size or otherwise. Tubes, shafts, and structural shapes may be easily and quickly cut by this means, although there is difficulty in cutting cast iron due apparently to the carbon it contains. Rivet heads are quickly cut off without marring the riveted plates, and any tangled mass of iron or steel wreckage, old boilers, or the hull of a ship may be easily cut to pieces by this method. In cutting a hole of several inches diameter in a steel plate, a small hole is first drilled to give the burner a start.

Hydrogen is more effective for this cutting than is acetylene, as the former makes a hotter flame. For light cutting, a blow pipe may be used which has no extra oxygen tube attached. The flame is given an excess of oxygen from the regular tube, making it an oxidizing flame.