364 



LORD HAYLEIUH ON THE COMPRESSIBILITY OF GASKS 



The gas was prepared from ferrocyanide of potassium and sulphuric acid,* and 

 purified from C0 2 by a long tube of alkali. It is barely possible that the abnormally 

 high number which stands first in the table may be due to imperfect purification on 

 that occasion ; on principle, however, it is retained, as no suspicion suggested itself at 

 the time. 



NITROGEN. 



The " chemical " nitrogen was from potassium nitrite and ammonium chloride. 

 That "from air" was prepared by bubbling air through ammonia and passing 

 over red-hot copper and sulphuric acid, with the usual precautions. It contained 

 about 1 per cent, of argon ; but this could hardly influence the observed numbers. 



OXYGEN. 



It remains to record certain results with air (free from H 8 O and C(X). It is 

 curious that the greatest discrepancies show themselves here. 



The earlier observations, at the end of 1902, were made before the apparatus 

 was perfected, and gave as a mean B = 1 '00022. Subsequently, return was made 

 to air. 



* See ' Roy. Soc. Proc.,' vol. 62, p. 204, 1897 j ' Scientific Papers,' vol. 4, p. 347. 



