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INTRODUCTION DEMONSTRATIONexperiments which are simple are more effective than those which involve complicated set-ups and elaborate technic. While the latter may give exact data, the refinements are wasted if the audience cannot interpret the results with * The experimental work on this paper was supported in part by the National Youth Administration.

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In the development of molecular theories of liquid and polymer structure, great importance is attached to stress and time dependences of the apparent viscosity of materials and their solutions. Some of these dependences can be accounted for by the heating of the fluid which is a consequence of the flow. In this report, solutions for the time and space distributions of the temperature in an incompressible fluid flowing steadily in a capillary with isothermal walls are presented. A comparison of the computed temperature changes with observed changes in apparent viscosity of some lubricating oils suggests that the temperature effect is significant. The possible usefulness of the solutions for understanding the origin of turbulence in flow and the heating of a cylindrical rod loaded in torsion is also discussed.

Experiments relating to the chemistry of the technologically important cellulose-formalde hyde reaction are described. While for many reasons definitive statements about the reaction cannot now be given, certain of its gross features are revealed. As the formalization process is usually carried out, the reaction with cellulose is com petitive with the evaporation of the formaldehyde. At low temperatures (to 30°C) no reaction takes place. At higher temperatures (150°C) reaction takes place over a wide range of con ditions of acidity. The product formed at high acidity is stable to hydrolysis and is charac terized by reduced swelling, increased elastic modulus, and resistance to creep. At lower acidities and under alkaline conditions, the properties of the product are much more like those of the starting material and the formaldehyde is easily removed by washing in neutral aqueous solutions. The combining weight of formaldehyde with cellulose varies, among other things, with the concentration of the formaldehyde applied. The lower the concentration the more nearly the combining weight approaches 12, which corresponds to the formation of simple methylene ethers with the cellulose. At higher concentrations, the combining weight increases toward a value of 30, indicating the formation of polyoxymethylene ether linkages.