Thomas Graham first directed attention to the desirability of a study of the flow of pure liquids in connection with their other physical as well as chemical properties. A serious attempt to realize this purpose was made by Pribram and Handl who noted the increase of viscosity with the molecular weight and attempted to establish a relationship. Rellstab observed the apparently important effect of chemical constitution in that metameric substances do not in general have the same times of transpiration. Brühl, perhaps too optimistically, inferred that among metamers those having the greatest viscosity have also the greatest density, the highest boiling point and the greatest refractive index. To this generalization, however, Gartenmeister found numerous exceptions; by securing unprecedented standards of precision in measurement, Thorpe and Rodger hoped to be able to assign exact viscosity values to each atom. Their excellent data seemed, however, to shatter this hope rather than to justify it.