THE VISCOSITY OF WATER. 47 
Capillary I., circular cylinder, radius °018968 cm. at 0° C. 
59, Pet besiii 95 r » 018916 ” 
», III., elliptical cylinder, semi-axes (a) ‘020762 ,, 
(b) °020076 ,, 
Be oe : aay 020061) 
(b) 019919 ,, 
III., mean radius of efflux R (where R= 200" a*b*\ 
i : a? +b? / 
) = °020413 cm. 
, LV., mean radius of efflux R — °020474 cm. 
An accuracy of 1 in 1000 was aimed at throughout the 
experiments. The values for the constants in the reduc- 
tion formula having been obtained, the viscosity was 
determined from the various observations which had been 
made from time to time, including those already mentioned. 
A special set of experiments at 0° C. was made at a fixed 
pressure in order to obtain accurate values of the viscosity 
at 0° OC. The thermometer registered 0°05° O. throughout 
the series. With tube I in the glischrometer, under a 
pressure of 197 cm. of water, the average time of flow was 
109°7 secs. The first term of the reduction formula was 
found to be °018690, and the second term °000769. The 
value for the viscosity at 0°05° was °01792 ; which reduced 
to 0° C., becomes ‘01795. A second determination gave 
the same values practically. The observations and reduc- 
tions are given on page 48, alsoa similar set at 25° O. p. 49. 
Most of the experiments, however, were carried out at 
50° C. with the water flowing under different pressures. In 
the following tables (p. 50) are collected the various results. 
The pressures are given in centimetres of mercury, the 
times of flow in seconds, the values of viscosity (double 
observations) in absolute measure, and the kinetic energy 
correction—second term—also in absolute measure. The 
pressures and times are approximate, and the viscosity 
values are reduced to the even temperature 50° C. 
