188 Mr. C. Tomlinson on the Cohesion-Figures of Liquids, 



areas were respectively — A, 3 inches in diameter ; B, 6 inches ; C, 

 o\ inches; and D, 6 inches : another object in selecting D was 

 to notice the effect of a great body of water as compared with A. 

 Sulphuric ether was washed, and drops from a pipette depo- 

 sited on the centre of A. A moderately good figure was formed, 

 but it was strongly attracted by the thick sides of the glass. 

 When the ether was delivered to the centre of B, instead of the 

 usual sharp defined figure, about the size of a florin, a much 

 larger figure was produced, and this was distorted and torn by 

 the attraction of the larger surface and the sides of the vessel, 

 to which it bounded up with rapidity. The characteristics of 

 the figure were evident in the midst of the distortion. On C 

 the figure was most perfect and satisfactory. On D the figure 

 was not so much distorted as on B. The attraction of the sides 

 was not so strong; but it must be noted that the sides were 

 thin and upright, whereas in B the raised inner edge of the 

 plate was on a level with the surface of the water. 



On mixing a portion of the w r ashed ether with about one- 

 fourth of alcohol, good steady figures were produced on all four 

 surfaces. The figures were more nearly confined to one spot, 

 and the attraction of the sides was less marked, in consequence 

 of the stronger attraction of the water for the alcohol than for 

 the pure ether. 



Pipettes of two sizes were used, one with a small and another 

 with a larger aperture, without any particular change in the 

 structure of the ether figure. 



The effect of varying the surface is very marked in the case 

 of some of the essential oils. In general the larger surface pro- 

 duces the phenomena with much greater rapidity than the 

 smaller ; the patterns of the figures are also more minute, and 

 the colours more freely developed. For example, a drop of oil 

 of lavender on the water in the conical glass forms a large film, 

 with a display of the beautiful Carrigeen-moss pattern, character- 

 istic of this oil. The pattern sets in from holes in the film. 

 When, however, the drop is deposited in the centre of B or D, it 

 flashes out into a large film with a transient display of colour ; 

 the pattern is minute, and is produced with great rapidity, 

 setting in from the edge and meeting the forms produced from 

 holes in the central parts. On the larger surface D, a large 

 shadowy outer film is produced more perfectly than on the other 

 surfaces. This secondary film is formed by the more fluid and 

 volatile portion of the oil, and is not an uncommon feature in 

 the films of essential oils. 



The influence of extended surface, as well as increased volume 

 of water, may be seen by the phenomena attending the formation 

 of other lavender films on the same surface. A second drop of 



