504 .Sir W. Ramsay and Dr. B. D. Steele on the 



is unimportant ; the correction is given under heading h in 

 the table. 



The temperature o£ y, the lower portion o£ the volume- 

 tube, is ascertained by means of the long-bulbed thermometer 

 previously described^ and its correction is given under heading 

 c ; the temperature of 5, its upper part, is that of the vapour- 

 jacket, and the correction is given under heading d. Cor- 

 rections for the portions x and y are not so important since a: 

 is small, and since the two limbs of y are of the same length 

 and at the same temperature. A constant correction of a f ew 

 hundredths of a millimetre was made for section /r when the 

 temperature of a was much low^er than that of the room. 



Further corrections have to be applied for depression due 

 to capillarity in the manometer-tube, and for vapour-pressure 

 in the volume-tube ; the former of these is already applied to 

 the figure given under the heading "manometer.'^ Hence, 

 if the actual reading of the manometer is m, its true height 

 is m^a — h — e, w^here e is the correction due to vapour- 

 pressure of mercury in the volume-tube. From this has to 

 be subtracted the height of the mercury in the volume-tube. 

 The position of the external point (fig. 1) is directly 

 measured ;" to its height must be added the vertical distance 

 betw^een the points and 1, plus the correction for linear 

 expansion of the glass; point (0 — 1) -h/ gives the actual 

 height of the mercury which has to be corrected for tempe- 

 rature by subtracting the quantities e and d; hence 



Pressure corrected to 0° 



= {m — a — h—e) — (point + point (0 — 1 ) +/— c — d) , 

 — {m + c + d)— (point + point (0 — 1) +/-f a + h-\-e). 



The pressures thus found must finally be corrected for the 

 change in volume brought about by the cubical expansion of 

 the glass ; this correction is given under the heading k. For 

 these experiments the correction applied to section x is 

 0-06 mm. 



The jacket d' (fig. 4) w^as so constructed that it was possible 

 to insert the delicate thermometer t into the inner tube s ; 

 and it was thus possible to obtain the values of its graduations 

 in terms of the oxygen scale. 









Table I. 









The coefficient of the 



expansion 



of 



oxygen. 



I. 



Temperature 



0°C. 













A. 



. length 



= 542 inms. 



temperature 



= 8-9° 





B.. 



• 



= 172 „ 



,, 





= 15-8° 





C. 



5) 



= 118 „ 



>) 





= 7-8° 





D. 





= 16 „ 







= 0-0^ 



