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XLIII. On the Cohesion-Figures of Liquids. 

 By Charles Tomlinson, F.C.S.* 

 [With Two Plates.] 



AT the Meeting of the British Association at Manchester in 

 1861, I had the honour of submitting to the Chemical 

 Section a subject then new to science, namely, the cohesion- 

 figures of liquids. In the memoir that was readf, I endeavoured 

 to show that when a drop of an independent liquid (that is, not 

 a solution) is gently deposited from the end of a glass rod or 

 from the point of a dropping-tube upon chemically clean water 

 in a chemically clean glass, the drop flashes out into a definite 

 figure as it enters into solution or diffuses over the surface. 

 Each figure is characteristic of the liquid, and is a function of 

 the cohesive force and diffusibility of the liquid, and the adhe- 

 sion of the surface on which it is deposited. The figure may 

 also probably be represented in other ways. It may be a function 

 of the solubility and the diffusibility of the liquid in question, 

 or of the solubility, the density, and the molecular attraction; 

 while in the case of certain figures which are produced beneath 

 the surface, and which I have named submersion figures, each 

 figure seems to be a function of the solubility, the density, and 

 the molecular attraction. 



In the production of cohesion-figures, water is the most con- 

 venient adhesion surface. It must be contained in a glass that 

 is kept chemically clean by occasional washing in sulphuric acid 

 or in a solution of caustic potash, so that the water, which need 

 not be distilled, may present a chemically clean surface. A 

 shallow glass about 4 inches in diameter is adapted to these 

 experiments. I have had a number of such glasses made for the 

 purpose, and have placed a couple of them upon the table. The 

 temperature best adapted for these experiments is that of an 

 ordinary room, which in winter or summer may be taken at 

 about 60°. I have not studied these figures by artificial light, 

 but have been informed that they admit of being reflected in an 

 enlarged form so as to be seen by an audience. I have published 

 various precautions respecting these figures, both with respect to 

 temperature and variations in the area of the adhesion surface. 

 I have also shown how these figures may be applied to the de- 

 tection of adulteration in liquids, and also how suggestive many 

 of these figures might be to the pattern-designer, from the great 

 beauty and novelty of form and the exquisite harmony of colours 

 displayed in them J. 



* Communicated by the Author, having been read before the British 

 Association at Bath, September 15, 1864. 



t Phil. Mag. for October 1861. \ Ibid. March 1862. 



