0.034 cM. ; the mean height of pressure is 11. B cm., which gives 

 for the correction 0.37o. For water at 30° with <j = 71.0 it is also 0.37o. 

 The capillary rise of water in the capillary at 0° was 8.0 cm., 

 that of butane at the same temperature 2.4 cm. ; the correction for 

 the time of flow was therefore for butane 0.09 "/o '• this may be 

 regarded as constant in the field of temperature used. 



Reynolds's critical velocity. 



To make sure that the velocity of the liquid remained below 



Reynolds's critical value, an estimation was made. The volume of 



the upper bulb was about 3.5 ccm. ; the capillary tube was fully 



11 cm. long, the diameter of the capillary tube D was 0.038 cm., 



the viscosity i^ is about 0.002, the density d at 0° is 0.60, and the 



Ddv 

 time of flow 300 seconds. With these data we find for the 



value 117, which is far below Reynolds's critical value (2000). 



Determinations with water. Influence of the temperature. 



The water used was . doubly distilled. Great care was taken to 

 keep it free from dust. It was renewed from time to time, which 

 had ho\vever very little influence upon the results. 



The viscosimeter was placed in a water-bath, which was kept in 

 circulation by a rotating screw and at constant temperature by 

 means of an adjustable number of platinum spirals through which 

 an electric current was passed. Everything was bound round with 

 cotton wool, which was partially removed at the beginning and end 

 of the time determinations. The temperature was read e^'ery minute. 

 The greatest difference during one observation was 0.07°, in the 

 second series during 54 minutes it was 0. 



During the measurements at 0° the viscosimeter stood in ice. 



The two ends of the U-tube were covered by glass caps. After 

 each determination the liquid was sucked up by a water pump. 



I temp. time 



31 Oct. '12 26.05 12 m. 11.4 s. 



25.99 11.4 



26.03 11.6 



26.03 1J.7 



26.05 11.2 



mean 26.03 731.5 s. ' 26.48 726.6 s. 



Corrected for capillarity 729.3 sec. 724.4 sec. 



II temp. time 



1 Nov. 26.48 12 m. 6.8 s. 



26.48 6.7 



26.48 6.2 



26.48 6.6 



