142 



SCIENCE 



[N. S. Vol. XXXIV. No. 866 



teristie inflated mass of ammonium amal- 

 gam is produced. 



The very high electrolytic solution ten- 

 sion indicated by these reactions is con- 

 firmed by direct potential measurements. 

 The values obtained, for similar conditions, 

 are about .6 volt higher than those found 

 recently by Lewis and Kraus for sodium 

 amalgam. This result is in harmony with 

 the enormously greater activity towards 

 water of the organic amalgam. Dr. Moore 

 and I have also made mono-methyl am- 

 monium amalgam and studied its proper- 

 ties. 



The facts just discussed point clearly to 

 the probability that in general positive 

 ions, if free, or even amalgamated with 

 mercury, will possess metallic properties. 

 Practically, however, several causes may 

 prevent the isolation of such metallic 

 bodies. "We know that it is not possible 

 by electrolysis to separate many metals like 

 sodium from aqueous solutions of their 

 salts. Similar relations may obtain in the 

 electrolysis of an organic salt. On the 

 other hand, it is theoretically possible that 

 such a compound metal may be so unstable 

 in the free state that it suffers spontaneous 

 decomposition at the moment of its forma- 

 tion from its ions. A third possibility is 

 exemplified by the case of hydrogen. For 

 a long time it was thought by some chem- 

 ists that hydrogen in solid form would 

 have metallic properties, since acids may 

 be considered ' ' hydrogen salts. ' ' The fact 

 that solid hydrogen is now known to have 

 no metallic properties proves clearly the 

 fallacy of the old idea and seems to be also 

 a flat contradiction of the hypothesis in 

 question. 



Now, hydrogen differs from the metals 

 in one other important respect: while the 

 molecules of metallic vapors are . always 

 monatomic those of hydrogen are diatomic. 

 Thomson has considered the question of 



the theory of the union of two like atoms 

 to form a molecule of an elementary gas, 

 and has shown very convincingly that it is 

 reasonable to conclude that one atom sends 

 its valence electron into the other and that 

 the combination is entirely analogous to 

 that when two unlike atoms combine. If 

 this is the case, it is possible to understand 

 why solid hydrogen has no metallic prop- 

 erties ; its valence electrons are hound and 

 not free nor mobile. Analogously to hy- 

 drogen, some organic radicals which can 

 form positive ions of salts may unite in 

 pairs to form double radicals. These 

 would not be expected to have metallic 

 properties. 



In some cases, however, even hydrogen 

 seems to have some metallic properties; it 

 dissolves readily in palladium and, when 

 nascent, diffuses easily through iron. The 

 latter property of hydrogen may be due to 

 continued existence in the monatomic and 

 therefore metallic state. 



As I have tried to point out, the electron 

 theory of the metallic state would lead us 

 to expect that free radicals, formed by the 

 neutralization of the positive ions of salts 

 by the introduction into each ion of that 

 number of electrons represented by its 

 valence would have metallic properties. 

 The facts just reviewed, though few in 

 number, seem to me to lend support to this 

 hypothesis, and to lead to the conclusion 

 that it is possible to prepare composite 

 metallic substances, which may be termed 

 synthetic metals, from constituent ele- 

 ments, some of which at least are non- 

 metallic. 



Herbert N. McCoy 



December 28, 1910 



WILLIAM EUSSELL DUDLEY. 

 William Eussell Dudley, professor of 

 systematic botany in Stanford University, 

 was born on a farm in North Guilford, Conn., 



