These experiments can be considered exploratory only. However, they do demonstrate the presence of large normal pressures in the presence of flat shear fields which were forecast by the theory in the first part of the paper. They also give information which will aid in the design of a more satisfactory instrument for the measurement of the normal pressures. Such an instrument would be useful for the characterization of many commercial materials as well as theoretical studies. The elasticity as a parameter of fluids which is not subject to simple measurement at present, and it is a parameter which is probably varying in an unknown manner with many commercial materials. Such an instrument is expected to be especially useful if it could be used to measure the elasticity of heavy pastes such as printing inks, paints, adhesives, molten plastics, and bread dough, for the elasticity is related to those various properties termed ``length,'' ``shortness,'' ``spinnability,'' etc., which are usually judged by subjective methods at present.

The actual change ** f caused by a shear field is calculated by multiplying the pressure differential times the volume, just as it is for any gravitational or osmotic pressure head. If the volume is the molal volume, then ** f is obtained on a molal basis which is the customary terminology of the chemists.

Although the ** f calculation is obvious by analogy with that for gravitational field and osmotic pressure, it is interesting to confirm it by a method which can be generalized to include related effects. Consider a shear field with a height of H and a cross-sectional area of A opposed by a manometer with a height of h (referred to the same base as H) and a cross-sectional area of a. If ** f is the change per unit volume in Gibbs function caused by the shear field at constant P and T, and |r is the density of the fluid, then the total potential energy of the system above the reference height is ** f. ** f is the work necessary to fill the manometer column from the reference height to h. The total volume of the system above the reference height is ** f, and h can be eliminated to obtain an equation for the total potential energy of the system in terms of H. The minimum total potential energy is found by taking the derivative with respect to H and equating to zero. This gives ** f, which is the pressure. This is interesting for it combines both the thermodynamic concept of a minimum Gibbs function for equilibrium and minimum mechanical potential energy for equilibrium. This method can be extended to include the concentration differences caused by shear fields. The relation between osmotic pressure and the Gibbs function may also be developed in an analogous way.