A process for coking coals water substance heavy oils

摘要

752,056. Plastic tubes. OWENS-ILLINOIS GLASS CO. Oct. 18, 1954 [May 11, 1954], No. 29886/54. Class 99(2). [Also in Group V] Concentric tubes, which may be separate as in Fig. 1, or joined to form a laminated tube as in Fig, 7, or separate for part of their lengths, are made by extruding plastic material through a die. The plastic material of one tube may be different from that of the other.