360 Mr. C. Tomlinson on the Cohesion- Figures of Liquids. 



tooth projects a number of globules, the ultimate figure being a 

 small disk in the centre with an immense number of dots radia- 

 ting towards it. In fig. 9 an attempt is made to represent this 

 effect, first as the figure is expanding, and secondly as it is retreat- 

 ing. On cold castor oil a similar figure is produced, only the dots 

 are more numerous and finer ; and there is a very curious differ- 

 ence in the figure of a drop of the wood-spirit of commerce as 

 compared with that of the pure spirit. On cold olive oil and on 

 lard at 120°, or on cocoa-nut oil at a lower temperature, the 

 drop of impure spirit forms a small lens with ten or twelve short 

 blunt arms projecting from it (see fig. 10), and each arm shoots 

 out a multitude of globules ; and not doing so in equal times 

 from each arm, there is a reactionary movement, which causes 

 the disk to describe half a turn in one direction and then half a 

 turn in an opposite direction, the effect of which is to dispose 

 the dots not in radial, but in curved lines, the curves often bend- 

 ing in opposite directions. The formation of the figure is suffi- 

 ciently slow to allow it to be studied, and the effect is very curious. 

 The difference between the two figures distinguishes the pure 

 from the impure spirit in a very marked manner. It should be 

 noticed that the surface of the oil soon becomes saturated, so 

 that not more than two or three figures can be produced in suc- 

 cession ; but by wiping the surface with a piece of filtering paper, 

 its adhesion is restored. 



Sulphur. — When sulphur is melted so as to be sufficiently 

 liquid to pour easily, some good figures may be formed on its 

 surface. A drop of ether at first assumes the spheroidal state ; 

 it then forms a boss surrounded by two or three rings of the 

 thinnest orders of colour, steel-blue prevailing, and the figure is 

 bounded by an excentric ring some way off. Benzole forms a 

 good figure, consisting of a boss, an irregular star from which 

 small lenses are shot out, and these are circumscribed by a flat 

 circle (PL V. fig. 15). Oil of lavender forms a boss surrounded 

 by iridescent rings in waving lines, then a large silvery space, 

 and a narrow boundary ring of iridescent colours (see fig. 13) . The 

 oils of rosemary, turpentine, and paraffin form each a boss sur- 

 rounded by large wavy iridescent clouds of most brilliant metal- 

 lic colours, paraffin oil being most brilliant of all. Creosote and 

 carbolic acid form disks which flatten out into waving figures (see 

 fig. 12). The figure formed by camphorated spirit is shown in 

 fig. 8. Camphor moves about over the surface; water forms 

 and occupies a cup- shaped cavity, solidifying the sulphur as it 

 evaporates. 



Submersion Figures, 



In the Philosophical Magazine for June 1864, 1 have described 

 a new variety of the cohesion-figures of liquids, in which the 



