Ex Parte FORBES et al - Page 5

          Appeal No. 1999-2775                                                        
          Application No. 08/549,847                                                  

          the cold gas flow is by using liquefied gas, such as liquefied              
          nitrogen, or a mixture of liquefied gas and compressed air                  
          (col. 3, lines 13-22).                                                      

          Peter discloses an assembly for providing a flow of cold air                
          (e.g., minus 40 F) to a workpiece on the bed or table of a drill           
          press, grinder, or milling machine (col. 3, lines 17-18), wherein           
          the apparatus includes a vortex tube assembly (11) having an                
          inlet (23) coupled to a compressed gas line (19) and an outlet              
          (31).  According to the examiner, "Peter teaches providing cold             
          gas through the use of a vortex tube which produces cold gas                
          without moving parts or electricity, in which a filter or dryer             
          is used and a chiller or antifreeze injectors (col. 2, lines                
          5-20)" (answer, page 3).  From the combined teachings of                    
          Lubbering '242 and Peter the examiner concludes that it would               
          have been obvious to one of ordinary skill in the art at the time           
          appellants' invention was made to utilize the vortex tube type              
          cold gas supply apparatus of Peter as a substitute for the cold             
          gas supply disclosed in Lubbering '242, in order to produce cold            
          gas efficiently and inexpensively.                                          

          In the alternative, the examiner notes that the Vortec                      
          Catalog teaches using a vortex tube in a cold air gun to cool               


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