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VII. Experimental and Theoretical Researches into the Figures 

 of Equilibrium of a Liquid Mass without Weight. — Seventh 

 Series*. By Professor J. Plateau t. 



Further examination of the glycerine-solution ; methods of prepa- 

 ring it, which are much more certain and effectual than those 

 first given. — Theory of the production of liquid films {continued); 

 applications of the theory. — Various kinds of liquid films. — 

 Theory of the production of liquid veins. — General principle re- 

 lating to the actual formation, by means of liquid films , of sur- 

 faces whose mean curvature is zero, 



AT the date of the publication of the Fifth Series of these re- 

 searches, I had made numerous trials in order to rind the 

 best way of preparing the glycerine-solution, and I believed that I 

 had succeeded. In fact, on the one hand, a bubble of 1 decimetre 

 diameter, blown with the solution as I was in the habit of pre- 

 paring it at that time, lasted for three hours when supported on 

 a ring of iron wire in the open air, a duration which necessarily 

 seemed enormous in comparison with the couple of minutes 

 which is the longest time that a bubble of the same size, blown 

 with a mere solution of soap, will last under the same circum- 

 stances ; and, on the other hand, several successive preparations 

 made in the same way had given me the same result, so that 

 I considered my method of preparation sure. But on prepa- 

 ring fresh quantities of the solution during the following summer, 

 although I still used English glycerine and Marseilles soap bought 

 at the same shop, I no longer met with the same success. I 

 therefore felt it needful to take up again the examination of the 

 glycerine-solution, with a view to finding surer and more generally 

 applicable processes of preparing it. I have thus arrived at a 

 simple theory of the solution in question, an exposition of which 

 may be found in my complete memoir, and which has led me to 

 adopt methods of preparation whose success I can now, I think, 

 guarantee as almost perfectly certain, inasmuch as I have em- 

 ployed them a great many times with glycerine obtained from two 

 different sources and with two different kinds of soap. These new 

 processes, moreover, give a degree of permanence to the films 

 which is greatly superior to the most successful results formerly 

 obtained. 



I still consider the English glycerine (Price's), recommended 



* For translations of the previous series see Taylor's Scientific Memoirs, 

 vol. iv. p. 16, vol. v. p. 584; and Phil. Mag. (S.4),vol. xiv. p. 1 ; vol. xvi. 

 p. 23 ; vol. xxii. p. 286, and vol. xxiv. p. 128. 



f Translated from the author's abstract (published in the Annates de 

 Chimie et de Physique, S. 4. vol. viii. p. 362, August 1866) of the original 

 memoir contained in the Memoires de I'Acade'mie de Bruxelles. vol. xxxvi. 



