446 On the Relative Rates of Effusion of some Gases. 



Summary of Results, 



1. Argon is found to effuse, when compared with oxygen, 

 3 \ per cent, faster than as calculated by the law o£ the inverse 

 square root o£ the density. This result is independent of any 

 masking effect due to viscosity. 



2. This result is in qualitative agreement with the adiabatic 

 theory of the efflux of ideal gases, and is, if this may be 

 granted, a confirmation of the high specific-heat ratio of argon. 



3. When viscosity-effects are eliminated or allowed for, it 

 is found that hydrogen, oxygen, and carbon monoxide effuse 

 relatively in the manner predicted by the theory for ideal 

 gases possessing the same, or nearly the same, specific-heat 

 ratio. 



4. Carbon dioxide, when compared with oxygen, appears 

 to effuse about 1 per cent, faster than as calculated from the 

 densities. This result is not in accordance with the adiabatic 

 theory of the efflux of ideal gases. 



5. The results obtained for helium are not uniform, and are 

 affected by a viscosity-correction depending on an empirical 

 formula. They are sufficient, however, to show that the 

 behaviour of helium is unlike that of argon, a result which is 

 not foreseen by the theory. 



6. If account be taken of the deviation of ordinary gases 

 from the ideal laws, it is possible to obtain an expression for 

 the efflux which contains a correction-term involving the 

 constant K of the Joule-Thomson effect. 



7. The sign of this correction-term shows that a real gas 

 will effuse more rapidly or more slowly than an ideal gas of 

 equal density and specific-heat ratio, according as K is positive 

 or negative. 



8. The suggestion is made that possibly the anomalous 

 results obtained with carbon dioxide and helium may be thus 

 explained. The deviations of the observed results from the 

 results calculated for an ideal gas are, in the case of G0 2 , in 

 qualitative accordance with the theory proposed. In the case 

 of helium they would be so if that gas possessed a negative K. 



In conclusion I desire to express my deep sense of obligation 

 to Professor Ramsay, at whose suo-crestion t ^ 5 investigation 

 was begun, and whose valuable advice and assistance I 

 enjoyed throughout its course. 



I wish also to thank Dr. Travers for kind advice on many 

 occasions. To Mr. E. C. C. Balv's great skill and constant 

 advice and assistance I am more indebted than I can possibly say. 

 Chemical Laboratory, 



University College, London. 

 December 1899. 



