580 



SCIENCE 



[N. S. Vol. LIII. No. 1382 



centrated solutions: Miller Spencek and Albert 



G. LOOMIS. 



The ultra-violet arc spectrum of yttrium: L. F. 

 Yntema and B. S. Hopkins. The ultra-violet arc 

 spectrum of Y was measured, using the yttrium 

 oxide prepared by one of us for the determination 

 of the atomic weight value accepted by the Inter- 

 national Committee. The spectrograph used is an 

 autocollimating quartz prism machine manufac- 

 tured by Adam Hilger, of London. A current of 

 4 amperes at an E.M.F. of 220 volts was passed 

 between vertical copper electrodes, the lower of 

 which held the Y^Oj in its crater. Several promi- 

 nent lines, attributed to Y in the literature, were 

 absent, and several new lines were measured. The 

 results given are the mean of five determinations. 



On the viscosity of gelatin sols: Robert Her- 

 man BOGTJE. Experiments were carried out upon 

 gelatin sols to accurately determine the relation 

 between viscosity and concentration. The data 

 have been applied to Hatschek's formula for the 

 viscosity of emulsoids and the value A^/A, repre- 

 senting the volume occupied per unit weight of 

 dispersed phase, was shown not to be constant 

 with varying concentration, but to rise to a maxi- 

 mum and thereafter regularly decline. A tenta- 

 tive explanation is presented based upon the effect 

 which increasing concentrations of dispersed phase 

 will have upon the surface tension of the disper- 

 sion medium. An empirical expression defining 

 the departure of the values obtained under varying 

 conditions for Hatschek's constant is given. 



The structure of molecules of water: Irving 

 Langmuir. Dennison has recently shown by X- 

 ray crystal analysis that ice consists of molecules 

 of the formula HiO;. In view of our knowledge 

 of the structure of atoms it is not possible to ac- 

 count for the existence of this molecule on the 

 basis of quadrivalent oxygen atoms. If pairs of 

 electrons (duplets) constitute the valence bond, 

 there can be no such bond between the two oxygen 

 atoms. A structure for this molecule is therefore 

 proposed in which the four hydrogen nuclei bind 

 the two oxygen atoms. The duplet held by each 

 hydrogen nucleus has one of its electrons in each 

 of the oxygen octets, instead of the more usual ar- 

 rangement in which both electrons of a duplet 

 form part of the same octet. 



The purification of helium iy means of charcoal: 



L. FiNKELSTEIN. 



The importance of diffusion in organic electro- 

 chemistry: Egbert E. Wilson and Merrill A. 



YouTZ. The authors, in searching for definite 

 evidence of depolarization in the electrolytic halo- 

 genation of organic compounds, found that either 

 slow reaction rate or slow diffusion, or both, pre- 

 vented any marked depolarization. Experiments 

 on the oxidation of FeCl, in HCl gave surprisingly 

 accurate information as to the rate of diffusion 

 under a variety of conditions, and showed that 

 without stirring there is a film of stationary liquid 

 about 0.5 mm. thick through which diffusion must 

 take place. This emphasizes the great importance 

 of violent stirring and of the use of rapidly dif- 

 fusing inorganic carriers to extend the sphere of 

 the organic reaction from a surface to a volume. 



Observations on the drying and swelling of gela- 

 tine gels : S. E. Sheppard and F. A. Elliott. At- 

 tention is drawn to the importance of capillarity 

 in the first phase of drying of jellies. It is shown 

 that this, in conjunction with factors depending 

 upon the shape of the jelly, causes the formation 

 of an exo-skeleton tending to conserve or increase 

 the original external surface extension. It is 

 chiefly due to this, rather than to any internal 

 supermolecular structure, that dried jellies on re- 

 swelling in water tend to return to their original 

 concentration. 



Note on the influence of silver salts in catalyz- 

 ing the decomposition of ammonium persulphate 

 solutions: S. E. Sheppard and A. Ballard. The 

 influence of silver salts in facilitating the decom- 

 position of ammonium persulphate in solution, first 

 observed by H. Marshall and J. Inglis, has been 

 confirmed, and quantitative data on the rate of 

 change in relation to the silver content obtained. 



Further developments of the hydrogen elec- 

 trode: Felix A. Elliott. Two new forms of hy- 

 drogen electrode were described representing prob- 

 ably the limits of simplicity and ruggedness with- 

 out reducing accuracy and rapidity of operation. 

 Especial attention has been given in designing 

 this new apparatus to reduce the internal resis- 

 tance to the lowest possible value so that a less 

 sensitive and hence cheaper, simpler and portable 

 electrical measuring instrument might be used. 

 Such an instrument was described, working on the 

 potentiometer principle and employing a pivot type 

 movement. Examples of results obtained with the 

 two types of apparatus indicate that potentials 

 are reproducible to about 0.1 mv. 



Note on silver soap gels: G. Stafford Whitby. 

 It has been observed that the silver salts of the 

 fatty acids are capable of giving reversible gels 

 in a variety of organic liquids — particularly in the 



