i8o 



NATURE 



[August 4, 192, 



with in positive rays, although there is only one 

 electron left to hold the two protons in combination. 

 To this Mr. Fowler replied that although this may 

 be stable for an indefinite period in a vacuum, 

 aggregates of this type appear to be quite incapable 

 of resisting chemical combination — perhaps because 

 an odd electron passing from one nucleus to the 

 other would impart an electrical charge alternately 

 to one atom and the other, giving rise to an unstable 

 condition which would be particularly ready to 

 undergo chemical change. 



Prof. W. A. Noyes, after reviewing briefly the 

 history of the development of the theory of ionisation, 

 laid stress on the fact that the distinction between 

 polar and non-polar union is one of degree and not 

 of kind, the fundamental factor in both types of 

 union being the pairing of electrons. He also directed 

 attention to the fact that the elements, such as 

 lithium, sodium, potassium, rubidium, and cassium, 

 which are monoatomic in the gaseous condition, are 

 exactly those which have a single valency-electron 

 in the outer shell. 



Sir William Bragg made an important statement 

 in reference to the lengths of the carbon chains in the 

 fatty acids and esters. Each additional carbon atom 

 in the alcohol radical increases the length of the 

 carbon chain by 1-22 A.U. ; but for the acid radical 

 the average increment is only 0-97 A.U. This 

 remarkable result can be explained, while maintaining 

 a fixed distance of 1-5 A.U. between the carbon 

 atoms, by assuming, on the alcohol side of the mole- 

 cule, a simple zigzagging of the chain of atoms, 

 with a fixed tetrahedral angle of 109° 28', the branch- 

 ing of the chain being to the left and right alter- 

 nately. The increment on the acid side of the chain 

 can be explained by assuming the formation of a 

 zigzag chain of another type, the deflexions being 

 in the order LLRRLL, etc., instead of LRLRLR. 

 These two forms of zigzag appear to be initiated by 

 the two types of oxygen-linking in the -CO . O- 

 group, and then to be rigidly maintained in the two 

 chains. The structure suggested on the acid side of 

 the molecule may explain the alternation of physical 

 properties observed in the well-known odd and even 

 series of acids, since the increment of length is 

 alternately parallel to the chain and inclined at an 

 angle of 109° 28' to it. 



At the close of the session Prof. Victor Henri made 

 a brief communication in anticipation of the im- 

 portant paper which he delivered on the following 

 day. The discussion took place under tropical 

 conditions, which were so extreme that the session 

 was adjourned before the discussion had become 

 completely informal. An informal discussion was, 

 however, carried on in the cooler atmosphere of the 

 evening in the fellows' garden of Trinity Hall, to 

 which some sixty delegates adjourned after dining 

 together in the Hall of the College. The bringing 

 into direct personal contact of workers who had 

 previously known one another only by correspondence, 

 or by reading one another's published communica- 

 tions, was a most valuable feature of the conference, 

 and full advantage was taken of the opportunities 

 thus presented. 



The discussion, on Saturday morning, of the applica- 

 tions of the electronic theory of valency to organic 

 chemistry, was presided over by Sir Robert Robertson. 

 In opening the discussion. Prof. Lowry urged that 

 the electron has come to stay, and that sooner or 

 later organic chemists must take into consideration 

 the electronic structure of atoms and molecules. 

 These may prove to be a mere translation into a new 

 language of the structural formulae of Kekule and 

 van 't Hoff ; giving rise to a new nomenclature but 



NO. 2805, VOL. I 12] 



to no new conceptions. This is, however, unlikely 

 in view of the enormous advances that have followed 

 from the discovery of Dalton's atom, and of each 

 fresh detail of its structure. The electronic theory 

 of valence has already made a contribution of real 

 value by discriminating between two types of valency, 

 since a single bond can now be classified as depend- 

 ing either upon electron-sharing or upon electron- 

 transference. Prof. Lowry 's own contribution had 

 consisted in the suggestion that a double bond may 

 assume a form in which one linkage of each type is 

 present. This has led to a number of novel con- 

 clusions which have been set out in a paper published 

 in the April number of the Journal of the Chemical 

 Society and in a paper on " Intramolecular Ionisation 

 in Organic Compounds " contributed to the present 

 discussion. 



In summarising a second paper on " The Trans- 

 mission of Chemical Affinity by Single I3onds," Prof. 

 Lowry raised the question as to how many t\'pes of 

 valency the chemist would wish the physicist to 

 provide, and how many different mechanisms must 

 be invented to account for the transmission of chemical 

 affinities through chains of atoms. Prof. Lowry be- 

 lieves that only two types of valency are necessary, 

 and that principal and subsidiary valencies, partial 

 valencies, conjugated double bonds, carbonium bonds, 

 mobile hydrogen atoms, centric bonds and para- 

 linkages in aromatic compounds, are all manifesta- 

 tions of those electrostatic forces which Langmuir 

 describes as electrovalence. In the same way, the 

 unidirectional " general " effect, and the " alternating " 

 effects observed in conjugated chains, appear to 

 account for nearly all the phenomena observed in 

 the transmission of chemical affinity. Lapworth and 

 Fliirscheim have suggested cases in which alternating 

 effects appear to be produced in chains of single 

 atoms ; but other explanations (such as the steric 

 effects described by Sir William Bragg) appear to 

 be capable of accounting for most of these observa- 

 tions, and further evidence is needed before a third 

 mechanism of transmission need be admitted. The 

 evidence now brought forward by Lapworth and 

 Robinson may perhaps provide the unexplained 

 residue of observation which would make such a 

 mechanism necessary. Prof. Lowry 's paper also 

 contained a vindication of Vorlander's view that, 

 when its direct neutralising action is eliminated, 

 the amino-group possesses well-defined acylous pro- 

 perties ; it is therefore no anomaly for an amino- 

 acid to be stronger than the fatty acid from which 

 it is derived. 



Prof. Lapworth, in communicating a paper on 

 " Some Recent Contributions to the Theory of 

 Induced Alternate Polarities in a Chain of Atoms," 

 described six different theories which have been put 

 forward in order to account for these phenomena. 

 In criticism of the previous speaker, he stated that 

 he himself twenty years previously emphasised the 

 tendency of organic compounds to assume a " homo- 

 geneous " in place of a " heterogeneous " distribution 

 of valency. This is precisely the same phenomenon 

 that Prof. Lowry discussed under the heading of 

 " Crossed Polarities." As evidence of alternate 

 polarities in chains of atoms held together by single 

 bonds he quoted the biochemical oxidation of but>Tic 

 acid to /j-hydroxybutyric acid and then to aceto- 

 acetic acid. This case has also been quoted in- 

 dependently by Robinson. 



Prof. Robinson contributed a paper on " Octet 

 Stability in Relation to Orientation and Reactivity 

 in Carbon Compounds." He directed attention, as 

 Prof. Lapworth had done, to the fact that optical 

 activity is often preserved in chemical changes. 



