In the following 



formed under different circumstances. ■ 177 



case more than the hundredth part of itself. All substances capable 

 of being wet by the liquid give a drop of the same magnitude. 



These experiments were for the most part made with the fol- 

 lowing apparatus : — C represents the vessel containing the liquid 

 to be experimented upon; KA a strip of 

 clean calico dipping into the liquid and 

 partially plugging the lower extremity of 

 the tube, AB, fixed in a vertical position, 

 delivering the drop D into a light beaker 

 B. The strip of calico, acting on the 

 principle of a siphon, may be made to 

 convey the liquid into the tube with any 

 requisite degree of slowness by adding to, 

 or taking from, the liquid in the vessel C. 

 experiments, the adjustment was such that the interval of time 

 between the falling of any two consecutive drops was not less 

 than forty seconds. The lower end, B, of the dropping-tube 

 was formed into a sharp edge, so that the tube at the part in 

 contact with the liquid might be regarded as indefinitely thin. 

 ±rom five to ten drops of the liquid were allowed to fall into the 

 beaker, and then its augmentation of weight enabled me to find 

 the weight of each drop. The form of the drop is that of a 

 hypernoloid of double curvature, approaching a hemisphere at 

 the lower portion, concave towards its upper portion, and having 

 a contrary flexure about the middle. In order to determine the 

 weight of the drop corresponding to different temperatures, the 

 dropping-tube AB was inserted in a wide brass tube passing 

 through a hot-water bath, so that the drop of liquid, as it was 

 being formed, might attain the same temperature as the water 

 surrounding the wide tube. 



Other things being the same, the weight of a drop of liquid is 

 proportional to the diameter of the tube in which it is formed. 



Inis remarkable law seems to be fairly established by the fol- 

 lowing results of experiment. 



Table I.— Results of Experiment on the Weight of a drop of 

 Water, formed m thin tubes of different diameters, at constant 

 temperature 50°. 



Diameter of tube, 



in inches, 



D. 



Corresponding weight 

 of drop, in grains, 



Value of w by formula 

 w = 55D. 



•13 



•78 



71 



•25 



1-36 



1-37 



•30 



1-60 



1-65 



•39 



210 



214 



•50 



2-84 



2-75 



•56 



3-00 



3-08 



-62 



3-36 



3-41 



Phil Mag. S. 4. Vol. 27. No. 181. March 1864 



N 



