The viscosity of carbon dioxide was determined under considerable variation of temperature and pressure by Warburg and Babo* in 1882, but their results are rather incomplete. They determined a few viscosity pressure isothermals at temperatures above the critical temperature, one such isothermal for the liquid at 25° C., and a few values of the viscosity of the liquid under the pressure of its saturated vapour at different temperatures. Recently E. N. da C. Andrade, working at University College, began to determine the viscosity of carbon dioxide at different temperatures under the critical pressure by a continuous flow method. This involved the use of large quantities of CO
2
, which he obtained in the usual trade cylinders, and which he kept at the critical pressure by immersing the cylinder in a bath at the critical temperature. The cylinder communicated with the capillary tube, which was surrounded by water at any desired temperature, and through which the CO
2
was slowly allowed to escape into weighed potash bulbs. The mass of CO
2
absorbed in a certain time gave the quantity of CO
2
flowing through the capillary tube per second, and a manometer gave the difference of pressure at the two ends of the capillary. The weakest point in the method was the use of CO
2
from the ordinary cylinders, for it contains a considerable amount of moisture, which has a large effect on the viscosity, especially near the critical point.
The influence of temperature and pressure on macro- and micro-mixing in compressed fluid flows; mixing of carbon dioxide and ethanol above their mixture critical pressure
