Standard substances for the calibration of viscometers

Abstract

B. and J. call attention to the need of a standard substance with a viscosity greater than that of water. The present paper is confined to a description of work on a mixt. of water and pure sucrose. The compn. of the mixt. was detd. by the polariscope. The viscosimeter used was a U-tube fitted with a capillary limb surmounted by a bulb with constrictions. The bulb measured the vol. of the liquid forced through the capillary by applied pressure. The viscosimeter was connected with a manometer and an app. for the production of pressure. Using the following equation: h = CpT - C'r/T, h = viscosity, p = applied pressure, r = density of liquid, T = time, C and C' are constants abbreviated from the complete viscosity formulas. The viscosity of pure water was found to be 0.01005 c. g. s. units at 20°. The authors suggest the use of the unit "centipoise" equal to 0.01 part of the c. g. s. absolute unit. This "centipoise" is almost exactly equal to the viscosity of water at 20° (0.01005), and would be the specific viscosity of any substance referred to water at 20°. B. and J. measured viscosities of a 39.99% sucrose soln. from 0° to 95°. They found that their observations corresponded to the figures obtained from the equation: t = 0.597 (f + 20) - [1438.6/(f + 20)] + 38.24 where t = temp., f = viscosity. Their measurements on a 20.007% and 59.96% sucrose soln. gave values corresponding to the equation t = 1.472 (f + 5) - [323.2/(f + 5)] + 58.62 where t = temp. and f = viscosity.