Test liquid S1 is stretched horizontally by the method originally used for liquid M1 and later for liquid A1. The same technique's found to work well for two liquids in which the percentage of Decalin is respectively reduced by 5% and increased by 5%, compared with the original fluid S1 (S1A and S1B). A different form of test is used for the highly viscous liquid produced when all Decalin is removed from the liquid S1 (S1C). In tests of the first three liquids, the speed of a rotating cylinder which pulls a liquid jet from a nozzle is gradually increased and the stress, strain and strain rate in the jet as a whole obtained from the force on the cylinder, the liquid flowrate and the initial and final velocities of the jet. It is possible to treat liquid S1, in uniaxial extension, as either a liquid or a solid. In the range of extensional strain rates from 0.3 to 20 s-1, the extensional viscosity of liquid S1 varies between 100 and 4000 Pa.s, rising rapidly with increasing strain rate. The rise of extensional viscosity with increasing jet length occurs because (for equal initial and final velocities), the axial stress is almost unchanged, whilst the strain rate is decreased. This somewhat artificial behaviour occurs because total strain is having an important effect on axial stress and the concept of extensional viscosity is of limited value under these circumstances. The extensional modulus, based on a rubber-like model, lies between 11 00 and 3400 Pa. The extensional viscosity of liquid S1B is between 40 and 2000 Pa.s (modulus 700-2000 Pa), for S1A between 300 and 10000 Pa.s (modulus 5000-10 000 Pa) and for S1C between 4 x 10(4) and 6 x 10(5) Pa.s. There is evidence that liquid is increasingly pulled out of the feed vessel by elastic tension in the jet as the speed of drawing is increased (liquids S1B, S1 and S1A). The tension in extended filaments of viscous fluid S1C relaxes over a period of 1-2 min and the relaxation time may readily be measured. This is of the order 15 s for principal extension ratios between 9 and 150. The material has a rubber-like quality but will still flow in a viscous manner at extensional strain rates between 0.05 and 0.2 s-1.