﻿260 M. G. Quincke on the Capillary Phenomena 



8. I have further measured the capillary constants of the com- 

 mon surface of mercury with other liquids. 



The observations collected in Table VIII. were made on flat 

 drops of mercury in an aqueous solution of hyposulphite of 

 soda, water, and olive-oil, like those on flat drops of bisulphide of 

 carbon or chloroform in water (§ 7). For the observations on 

 flat drops of mercury and petroleum a trough was made of 

 plates of plate glass cemented with common glue ; for observa- 

 tions in absolute alcohol they were cemented with pure paraffin. 



In order to measure the vertical distance of the horizontal from 

 the vertical surface-element in flat drops of mercury on a hori- 

 zontal glass plate in a liquid placed in a glass beaker, a flexible 

 thick copper wire with a vertical thin sewing-needle at the end, 

 was fastened to the cathetometer. The needle-point was then 

 moved so as to touch the top of the drop or the horizontal glass 

 plate (where the needle-point and its image must have touched 

 one another), or was placed at an equal height with the vertical 

 meridian- element of the drop. The latter adjustment, however, 

 is difficult and inexact. 



The determinations from Nos. 3 to 7, for mercury and bisul- 

 phide of carbon, were made in this manner : for Nos. 3 to 5 the 

 values of a n were obtained from K— k; for Nos. 6 and 7 from 

 K V\, by which the marginal angle was put = 180°. 



Another part of the observations were conducted in the follow- 

 ing manner. A horizontal glass tube 18*3 millims. in length 

 and 25-8 millims. in diameter was closed at the ends by vertical 

 glass disks, which were pressed by screws against the evenly cut 

 thick wall of the glass tube. The latter was half filled with mer- 

 cury through an opening in the upper part of the tube; and upon 

 this the liquid was poured, for whose common limit with mer- 

 cury the capillary constant was to be determined. The depression 

 of the mercury at the vertical glass plane moistened by the spe- 

 cifically lighter liquid was measured with the cathetometer ; and 

 this was then, assuming the angle to be 180°, the constant de- 

 noted above (equation 6, § 3) by a 12 . Observations 1 and 2 for 

 bisulphide of carbon, 1 and 2 for petroleum, and 1 to 3 for 

 chloroform and mercury were made in this manner. 



By inclining the vessel and immediately observing the capil- 

 lary depression on the vertical glass side, I endeavoured to make 

 the marginal angle =180°. If the liquids are left long in con- 

 tact with the glass side, then in general the acute angle 12 > 0°, 

 as follows, for example, from the observations on turpentine and 

 mercury (see Table VIII.), where the angle n was found, from 

 the determinations of the height of the drop K, to be 47° 2 r , and 

 from the depression on a glass plate to be 11° 54/. 



For the observations on flat drops of mercury in petroleum 



