PROCEEDINGS 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. VII, pp. 2S9-299. Plate XIV. July 24, 1905. 



AN INTERESTING PSEUDOSOLID. 

 By George F. Becker and Arthur L. Day. 



As is well known, Professor J.J. Thomson's investigations 

 lead to the hypothesis that a molecule is a highly complex body 

 consisting of great numbers of minuter particles called cor- 

 puscles, so that a molecule would be more nearly comparable 

 to a swarm of meteorites than to, let us say, a planet. In 

 considering this theory, it occurred to us that a model might be 

 made from a mixture of liquid and gaseous ingredients, the 

 physical properties of which would very closely resemble a 

 homogeneous solid made up of such complex molecules. A 

 bubble of soap solution, or any other viscid liquid would enclose 

 great numbers of molecules of oxygen and nitrogen, all of 

 them in rapid motion, and representing the corpuscles of 

 Thomson's molecule, while the surface tension of the bubble 

 itself would replace the attraction of the systems of corpuscles 

 towards some interior point or points. The foam which ac- 

 cumulates in sheltered places on a rock-bound sea-coast, the 

 beaten white of an egg or the whipped cream products of the 

 pastry cook's art, represent very stable aggregates of such 

 imitation molecules while they are of a size and character to 

 admit of manipulation and study. 



In order to obtain experimental evidence as to the properties 

 of such foam, we prepared a prismatic mass of fine soapsuds 

 and attempted by torsion to ascertain whether its behavior re- 

 sembled that of a viscous liquid or a true solid. It is well 

 known that the behavior of a twisted prism is very characteristic 

 of the state of the matter composing it. A viscous liquid, such 



Proc. Wash. Acad. Sci., July, 1905. 289 



