1893.] 



on Liquid Atmospheric Air. 



and tend to confirm the Law of Gladstone as being applicable to 

 such substances : — 



Refractive Indices of Liquid Gases. 



Oxygen 



Ethylene .. 

 Nitrous Oxide 



Index. 

 1-2236 

 13632 

 13305 



Law of Gladstone 



Ref. Constant. 

 . .. 1-989 . 

 . .. 0-626 . 

 . .. 0-263 ., 



D 



= Constant, 



Eef. Molecular. 

 , 6-364 

 , 17-528 

 , 11-587 



Fig. 7. 



+ TEMP£RATUR£ — 



Electrical Resistance of Alloys at Low Temperatures. 



The determination of the refractive index of liquid oxygen, at 

 its boiling-point of — 182° C, presented more difficulty than would 

 have been anticipated. The necessity for enclosing the vessel 

 containing the liquid in an outer case to prevent the deposit of a 

 layer of hoar-frost which would scatter all the rays falling on it, 

 rendered manipulation difficult ; and hollow prisms with cemented 

 sides cracked with the extreme cold. It was only after repeated 

 attempts, involving the expenditure of a whole litre of liquid 

 oxygen on each experiment, that we succeeded in getting an approxi- 

 mate measure of the refractive index for the D line of sodium. 



