Chemistry and Physics. 311 



knowledge of the properties of matter. To command in our 

 laboratories a temperature which would be equivalent to that 

 which a comet might reach at an infinite distance from the sun 

 would indeed be a great triumph for science. If the present 

 Royal Institution attack on helium should fail, then we must 

 ultimately succeed by adopting a process based on the mechanical 

 production of cold through the performance of external work. 

 When a turbine can be worked by compressed helium, the whole 

 of the mechanism and circuits being kept surrounded with liquid 

 hydrogen, then we need hardly doubt that the liquefaction will 

 be efiected. In all probability gases other than helium will be 

 discovered of greater volatility than hydrogen. It was at the 

 British Association Meeting in 1896 that I made the first sug- 

 gestion of the probable existence of an unknown element which 

 would be found to fill up the gap between argon and helium, and 

 this anticipation was soon taken up by others and ultimately con- 

 firmed. Later, in the Bakerian Lecture for 1901, I was led to 

 infer that another member of the helium group might exist having 

 the atomic weight about 2, and this would give us a gas still more 

 volatile, with which the absolute zero might be still more nearly 

 approached. It is to be hoped that some such element or elements 

 may yet be isolated and identified as coronium or nebulium. If 

 amongst the unknown gases possessing a very low critical point 

 some have a high critical pressure instead of a low one, which 

 ordinary experience would lead us to anticipate, then such diffi- 

 cultly liquefiable gases would produce fluids having different phys- 

 ical properties from any of those with which we are acquainted. 

 Again, gases may exist having smaller atomic weights and densi- 

 ties than hydrogen, yet all such gases must, according to our 

 present views of the gaseous state, be capable of liquefaction 

 before the zero of temperature is reached. The chemists of the 

 future will find ample scope for investigation within the appar- 

 ently limited range of temperature which separates solid hydrogen 

 from the zero. Indeed, great as is the sentimental interest 

 attached to the liquefaction of these refractory gases, the import- 

 ance of the achievement lies rather in the fact that it opens out 

 new fields of research and enormously widens the horizon of 

 physical science, enabling the natural philosopher to study the 

 properties and behavior of matter under entirely novel conditions. 

 This department of inquiry is as yet only in its infancy, but 

 speedy and extensive developments may be looked for, since 

 within recent years several special cryogenic laboratories have 

 been established for the prosecution of such researches, and a 

 liquid-air plant is becoming a common adjunct to the equipment 

 of the ordinary laboratorj^ — Nature, Sept. 11, 1902. 



6. Vapor-2yressures of Liquid Oxygen and of Liquid Hydro- 

 gen. — In an abstract of a paper by M. W. Tkaveks, G. S enter 

 and A. Jaquerod read before the Royal Society on June 19 

 (Nature, vol. Ixvi, p. 382), the results contained in the following 

 table are given : 



