604 Transactions of the American Institute. 



the combination of these two characters — luster and conductiujj 

 power — the metallic or non-metallic nature of a body is always 

 distinguished." 



It is true, that tellurium is not malleable nor ductile, as are many 

 of the metals; neither 1$ bismuth or antimony. Like the non- 

 metallic substances, it unites with oxygen to form acid. So do 

 antimony, arsenicum, gold, chromium, manganese, and many other 

 metals. With hydrogen it unites, forming a hydruret; so do potas- 

 sium, arsenicum and antimony. In short, it possesses the univer- 

 sally admitted distinguishing characteristics of metals; and nothing, 

 either in physical character or chemical behavior, which it does not 

 hold in common with some other metals. I must therefore call 

 it a metal. 



Mr. H. F. Walling read the following paper, which was illus- 

 trated by experiments: 



WIRBEL-BEWEGTTNG, OR WHIRLING MOTION. 



It will be remembered that in the paper on Molecular Motions, 

 "which I read before you last winter, I took the position that atoms 

 have, jper se, no such properties as hardness, solidity, rigidity, 

 impenetrability, elasticity, etc., all of which I suppose to be mani- 

 festations of attendant force. 



I now wish to call your attention to a recent hypothesis, emanat- 

 ing from a high source in Europe, and having one feature of simi- 

 larity with mine, in that it diminishes the number of assumed 

 properties which are attributed to matter. 



Helmholtz, the celebrated German physicist and mathematician, 

 has recently investigated the dynamical properties of vortex rings, 

 and has arrived at some curious conclusions in regard to them. He 

 finds that the characteristic motion of these rings, to which he gives 

 the name "wirbel-bewegung," or whirling motion, would, if once 

 set up in a perfect fluid, continue forever. A "perfect fluid" is 

 one in which there is no viscosity or friction of the particles against 

 each other; no resistance to motion except that of inertia. Of 

 course, it would be just as impossible to originate such a motion 

 as to destroy it. 



Vortex rings, however, are very frequently produced in air by 

 friction against solids, etc., and are seen issuing from the muzzles 

 of discharged cannon, the smoke-pipes of locomotives, etc. Phos- 

 phoretted hydrogen, generated under water, usually leaves the 

 surface of the liquid in vortex rings. Smokers produce them by 



