342 



0,1 m.ni. octane, which corresponds to 0.005 ni.ni. mercilrj-pressure. 

 The accnracy of the measurements was within the limits 0,05 and 

 0,J 7oJ ^t ^^^^^ greater than necessary in comparison with the magni- 

 tude of the SAStematic errors of the njethod. 



The final form of the manometer, as it was used in all the measu- 

 rements is shown in fig. 5. This final form resulted from a great 

 number of experiments and niiuierous changes. The tube .4 is made 



Fig. 5. 



from the best quality of hard-glass, and connects two bulbs B of 

 ca. 39,9 mm. diameter with a volume of about 130 cubic centi- 

 meters ; (hey possess 1,2 mm. wall-thickness. The bulbs must carefull}^ 

 be chosen, and be completely cylindrical throughout their full length. 

 As the height is about 110 mm.~ it is not easy to find tubes of the 

 desired quality. The capillar}' tube must have an internal diameter 

 of about 1,7 or 1,8 mm., and a wall-thickness of about 2,5 mm., 

 and must be suitable for precision-measurements and carefully 



