Metals That Build New Worlds 183 



pounds, which all were pressed from powdered metals. The 

 parts can be produced so that they are within a few thou- 

 sandths of an inch of the correct dimensions. Very little cut- 

 ting, grinding, or chipping is required to finish the parts. 

 This means a great saving in scarce metals, skilled man power, 

 and time. 



Self-lubricating bearings are turned out by powder metal- 

 lurgy. The bearings are pressed of materials that become 

 spongelike when baked in the sintering oven. They soak up 

 oil and then gradually release it when in use. When a machine 

 stops running, the bearings absorb the oil. Self-oiling bearings 

 can be installed on tanks, and the crews never have to worry 

 about lubricating them. 



"Twenty-eight different metals are now being produced in 

 powdered form and used in various combinations to produce 

 tens of thousands of different products, but experts say that 

 this is only a beginning," wrote Robert W. Marks and Har- 

 land Manchester in Forbes magazine. "Already it gives prom- 

 ise of turning out everything from watch parts to locomotive 

 wheels with new speed and economy." 



Dr. C. K. Leith, head of the metals and minerals branch of 

 the Office of Production Research and Development of the 

 WPB, has briefly sketched the work of officials in charge of 

 getting new supplies of metals for war. "No nation," he said, 

 "has enough of all minerals. We are developing low grade 

 supplies at home which have never been used before. We are 

 devising new processes for the concentration and improve- 

 ment of these low grade materials and for their conversion 

 into usable form." 



In the past two years the United States Bureau of Mines 

 has been conducting a hunt for war metals that has rivaled the 

 gold rush of '49. Low-grade ores of zinc, lead, nickel, tung- 

 sten, chromium, molybdenum, manganese, and other strategic 

 metals have been uncovered by engineers. Then chemists 



