Three types of measurements have been made on concentrated polyisobutylene solutions. Dynamic measurements have been extended to low frequencies and the dynamic viscosities and rigidities determined in the region close to that in which pure viscous flow predominates. A modified Stormer viscometer has been used to determine the apparent (non‐Newtonian) viscosities of the same solutions. Pressures developed (normal stress) at the inner cylinder have also been measured in a concentric cylinder apparatus with the inner cylinder rotating. It is noted that superposition procedures currently used for dynamic data are apparently applicable to the viscosity and pressure data with the rate of shear taking the place of frequency. Relations between these phenomena are discussed in the light of a theory proposed by one of the authors.