304 Professor Dewar on the Liquefaction of Gases. 



Poxy gene perd les caracteres actifs possedes par cet element 

 dans Fetat gazeux ; il est sans action sur le phosphore, le 

 sodium, le potassium, l'hydrogene sulfure solide et l'acide 

 hydriodique solide. D'autres substances paraissent eprouver 

 des changements semblables aux tres basses temperatures. 

 Ainsi l'ethylene liquide et le brome solide peuvent etre mis 

 en contact sans produire aucune action, tandis que l'ethylene 

 gazeux et le brome liquide s'unissent directement aux tem- 

 peratures ordinaires. 



" Hautefeuille et Chapuis, en soumettant un melange 

 d'anhydride carbonique et d'ozone a une grande pression, 

 out obtenu un liquide bleu dont la couleur est due a Fozone. 

 Si Fair ozonise passe dansdu disulphide de carbone a —100°, 

 le liquide prend une couleur bleue qui disparait quand on laisse 

 elever la temperature, et, a un certain degre, une decom- 

 position d'oii resulte une production de soufre. Le meilleur 

 dissolvant de Fozone est un melange de tetra fluoride de 

 silicum et de petrole de Bussie. Ces solutions d'ozone sont 

 sans action sur le mercure ou l'argent metalliques." 



Prof. Olszewski says : — " The experiments of Prof. Dewar 

 are merely the repetition and confirmation of these researches.' - ' 

 Reviewing the work I have been engaged upon during 

 the last few years, either by myself or in consort with 

 Profs. Liveing or Fleming, the following subjects have been 

 taken in hand and so far developed with regard to the pro- 

 perties of matter at low temperatures : — 



Construction of Apparatus for the production of Liquid 

 Air and other Gases in quantity — High Vacua — Vacuum 

 Vessels for Storage and Manipulation of Liquid Gases — 

 Cooling by Sponge of Liquid Air — Solid Air — Radiation at 

 Low Temperatures — Thermal Transparency — Refractive In- 

 dices — Spectroscopy — Electric Conductivity — Thermo-Elec- 

 tric Properties — Latent and Specific Heats — Capillarity — 

 Chemical Action — Magnetic Properties — Breaking-Stress of 

 Metals — Solid Matter and Argon in Liquid Air — Phosphor- 

 escence and Photographic Action — Liquefaction of Hydrogen, 

 &c. With the exception of the determination of the refrac- 

 tive indices of liquid oxygen my work has had nothing in 

 common with that of Prof. Olszewski. 



Now Prof. Olszewski says he has anticipated all this 

 pioneering work. On referring to his list of papers given in 

 the Philosophical Magazine for last month, I find that since 

 the year 1890 he has confined his attention to the refractive 

 indices of liquid oxygen and an attempt to corroborate 

 Wroblewski's determination of the critical constants of 



