80 



Infiuence of the total quantity of water. 

 All the determinations were made at 0°. 



Small quantities of water were added or drawn off. After each 

 series of determinations the viscosimeter was weighed with water 

 and at the end thé empty viscosimeter. From this follows the volume 

 of water at each determination, usually two measurements were 

 made in each series. The greatest difFei-ence between them was 1.4 

 sec. in a total time of 25 minutes, a difference of less than 0.1 "/u- 

 The results were the following: 



weight of water. time of flow. 



3,24 gr. 1470,3 sec. 



3,53 „ 1480,2 „ 



4,06 „ 1497,0 „ 



- 4,41 „ 1516,3 „ 



4,42 „ 1517,2 „ 



4,88 „ 1528,3 ,-, 



5.24 „ 1544,4 „ 



Grapiiicallj i-epresented these figures give a curve with two points 

 of inflexion. If the bottom reservoir were cyhndrical, the curve would 

 be a hjperboki, as the product of pressure aud time of flow is 

 constant. The deviation from the hyperbola which the curve shows 

 can be explained in every particular by the irregular form of the 

 bottom reservoir (bulb with a tube sealed in at the side;. 



Determinations with JS^orrnal Butane. 



The side tube A was connected to the reservoir which contained 

 the butane prepared according to Grignakd's method ^). After the 

 viscosimeter had been pumped out, the butane was distilled over. 

 For this purpose the lower bulb was cooled in a mixture of ice 

 and salt. After cooling the side tube was sealed off. 



The determinations above 0° were made in a water-bath, like the 

 determinationj: with water. The glass jacket, which consisted of two 

 coaxial tubes fastened by an india-rubber ring, was turned round 

 with the viscosimeter. The latter was clamped between two corks 

 in which a number of holes were bored. No determinations were 

 made above 35^ as then the internal pressure may exercise a very 

 uncertain influence upon the volume. The vapour-pressure of butane 

 at 35° is 3.5 atmospheres. 



At 0° the viscosimeter was placed in a wide test-tube which was 

 closed by a cork. Two glass tubes, fastened with sealing wax into 



1; J. P. KuENEN. Gomm. Phys. Lab Leiden, No. 125, p. 4. 1911, 



