ON THE COHESION FIGURES OF LIQUIDS. 
495 
It is insoluble in spirit of wine, but soluble in dilute sulphuric acid, from 
which it again separates on cooling. 
FURTHER REMARKS ON THE COHESION FIGURES OF 
LIQUIDS. 
BY CHARLES TOMLINSON. 
Lecturer on Science, King's College School, London. 
A wish having been expressed that some of the diagrams of cohesion figures, 
exhibited during the reading of my paper on the 3rd of February last, should 
be reduced and engraved on wood for insertion in the Journal, I think it due 
to the Society to make a few additional remarks in connection with these 
figures, which, as now presented, bear about the same relation to the originals 
as an engraving of a rainbow does to the real object. But although the ex¬ 
quisite beauty and harmony of colour of some of these figures is thereby lost, 
yet a certain rough idea is thus given of their form and outline, so that any 
one working on this subject for the first time may get a notion of the kind of 
form he has to expect. 
After the reading of my paper, a number of questions were put as to the 
variation of the figure by changing the surface, etc., and I stated that water 
seems, in all respects, to be best adapted for the exhibition of these figures. 
In a paper published in the ‘ Philosophical Magazine’ for March, 1862, some 
particulars are stated respecting variations in the figures arising from changes 
in the adhesion surface. Thus, a drop of water gently delivered to the sur¬ 
face of sulphuric acid from the end of a pipette, flattens down into a well- 
defined disk about the size of a shilling, marked with radial lines; these dis¬ 
appear at the centre, while fragments remain for some seconds, near the cir¬ 
cumference. Alcohol, ether, benzole, etc., on sulphuric acid give striking 
figures, showing how remarkable is the change when the adhesive force of the 
surface is varied by the substitution of some other liquid for water. 
When acetic acid is used as the adhesive surface, a new set of figures is ob¬ 
tained. Thus oil of camphor, which on water forms a large well-developed 
film, produces only a small disk on acetic acid (sp. gr. L045), which disk 
sails about with considerable agitation, throwing off numerous globules. Oil 
of lavender also forms a small disk, which gathers itself up with strange con¬ 
tortions, and illustrates in its own way the struggle that is going on between 
cohesion and adhesion. 
A question was also asked respecting cod-liver oil, when I stated that a 
specimen (A), supplied to me as pure, gave a certain figure ; that a specimen 
(B) purchased at a shop gave another figure ; but that on mixing two-thirds 
of common fish oil with one-third of A, I obtained a figure almost identical 
with that given by B. 
The first in the accompanying page of engravings is a portion of the figure 
of castor oil. Of course it will be understood that all these figures are com¬ 
plete disks or circles, of which portions only are here represented. They are 
produced on the surface of water contained in a shallow glass about four inches 
in diameter.* The following experiments were made on the 10th and 11th of 
* I have lately ordered a number of glasses resembling large claret-glasses; each glass stands 
on a wide foot, and the stem is rather long, for the convenience of handling ; so that the hand 
need never be brought into contact with the inner surface of the glass. After an experiment, 
a jet of water from a tap will often get rid of all traces of the oil of a former experiment. 
Should it not do so, the caustic potash solution must be used, and should this fail, sulphuric 
acid must he resorted to. A glass is left at the Society’s house, for inspection by members. 
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