different tubes are given in table i the air injected amounts to 0 87 volumes per volume of coagulating liquid water and air at 20 u00b0 c and 101 kpa similar results are obtained using initial tube lengths of up to 20 cm in length before the air injection the minimum air injection in order to be able to control the air gap and stagnant layer independently amounted to 0 5 and 0 61 volumes air per volume coagulating liquid respectively for 5 and 20 cm initial tube lengths a control the procedure of example 1 a is followed with an air gap of 9 mm a stagnant layer of 35 mm and a coagulating liquid flow of 23 to 27 l min fiber properties are given in table i b the spin tube of fig3 is used having an entrance inside diameter of 6 35 mm following tube inside diameter of 7 11 mm and a tube length of 100 mm before the tube is expanded to a continuing inside diameter of 8 64 mm immediately followed by the air injection holes 6 holes of 1 2 mm diameter equally spaced on the circumference of the tube a coagulating liquid flow of 13 l min an air gap of 8 mm a stagnant layer of.