444 SCIENCE PROGRESS 



On such a hypothesis the chief function of the impressed electric 

 force is to polarise the medium, i.e. dispose a number of mole- 

 cules into chains, while the actual current is largely due to the 

 forces developed by the charged ends of the molecules them- 

 selves. Indeed (and this is the bearing of the hypothesis on 

 Kammerlingh Onnes' work), if the temperature is sufficiently 

 low, and thus the ratio of the electric force to rotational energy 

 very large, the molecules once polarised will remain polarised 

 under their own mutual end attractions, the heat motion being 

 too feeble to knock them out of line. The original impressed 

 electric force may be removed without disturbing the polarisa- 

 tion, and the dragging of electrons round the chains formed in 

 the closed conductor will go on as before until the feeble heat 

 motion slowly " depolarises " the medium. Thomson shows 

 how his formula and curve lead to a definite temperature below 

 which this state of affairs exists and above which it cannot 

 exist. All the usual results connecting thermal and electric 

 conductivity with temperature are obtained, and a further 

 discussion shows how the properties of alloys as distinct from 

 pure metals can be accounted for. 



The older free electron theory has had such vogue in the 

 lecture room, and has of late suffered such adverse criticism, 

 that it would be well if every teacher of Physics read this very 

 important paper, so that what is undoubtedly a very promising 

 hypothesis may become much more widely known than it 

 seems to be at present. 



INORGANIC CHEMISTRY. By C. Scott Garrett, B.Sc, University, 

 Liverpool. 



Progress in inorganic chemistry has not been marked by any 

 sweeping generalisations or revolutionary advances such as 

 have been taking place recently in the sister science of physics. 

 Nevertheless a steady advance along detailed lines is going on, 

 and observations and data are being accumulated, which some 

 day will enable a master mind to shed brilliant new light on 

 the dark places of the science. 



Some observations on the reaction between chlorine and 

 sodium thiosulphate have been made by Self {Pharm. J. 191 5, 

 95, 133), and as they are of considerable importance at the 

 present juncture, it may be of general interest to mention 



