Welding with the oxy-acetylene' ﬂame is a fusing process. With a temperature of over F., concentrated in a comparatively small point, the ﬂame is held on the edges to be united until they melt together. Since by this process, no hammering or com pression is necessary, it is applicable to all the metals: cast iron, malle able iron, steel, aluminum, bronze and copper. Oxygen is purchased in conveniently handled cylinders or drums which are charged to a pressure of approximately pounds. Purity is essential to the successful and economical operation of the oxy-acetylene process and the oxygen purchased in these high pressure drums is considerably cheaper and much purer than that made by chemicals on the premises. The proper manufacture and testing of both the oxygen and acetylene cylinders is supervised by an U. S. Government commission and if ordinary precautions are employed by the user, the tank system of gases is ideal.