National Geographic : 1951 Oct
+ Gas Flames Smooth the Lip of a Glass Mug Natural gas, easily controlled, free of ash, and exact in desired temperatures, is ideal for the glass industry's purposes. Some 30 billion cubic feet of gas are con sumed each year by the Owens-Illinois Glass Company. In its Toledo, Ohio, plant, an annealer (right) places crystal ware in a gas-fired lehr. Reheating and gradual cooling will reduce internal stresses. 557 National (Thoranhie Phnt nrranhr- W1,ill a, P " Cl .on R,.hn..+ 71 ,,,.