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LI. On the Distillation of Liquid Air, and the Composition 

 of the Gaseous and Liquid Phases. — Part I. At Constant 

 Pressure. By E. C. C. Baly *. 



THE experiments described in this paper were commenced 

 with a view of obtaining the relation between the tem- 

 perature and the composition of the gas evolved from liquid 

 air boiling under atmospheric pressure, so as to render 

 possible the determination of the temperature of boiling air 

 by the analysis of the gas evolved. They were, however, 

 extended beyond this, and analyses were made of both the 

 liquid and gaseous phases for all mixtures of oxygen and 

 nitrogen, thus completing the investigation of the distillation 

 of liquid air under constant (atmospheric) pressure. 



The measurements of temperature were all made by means 

 of a Callendar compensated hydrogen-thermometer. This 

 instrument, which is a constant-pressure apparatus, differed 

 from Callendar's description f in that the measurement of 

 volume-change was read by admission of mercury into a 

 graduated burette, instead of being weighed. The tempera- 

 ture as shown by Callendar may be calculated from the 



,• rp V T 2 m 



equation 1 = ^ ^ ; 



where V is the volume of the thermometer- bulb ; 



V x the total volume of the thermometer-bulb and the 

 graduated burette ; 



V 2 the volume of gas measured in the burette during 

 the experiment; and 



T 2 the absolute (hydrogen) temperature of V 2 . 

 In the thermometer used throughout the experiments, the 

 volume V (at 15°) was 28'655 c. c. and the total volume V x 

 was 129-590 c. c. The adjustment in order to make both sides 

 of the apparatus, i. e. the compensating side and the thermo- 

 meter side, quite equal in volume, was very carefully per- 

 formed by means of the burette and then connexion was 

 opened between the two sections so as to ensure there being 

 an equal mass of gas on each side. The filling with hydrogen 

 was very carefully carried out. The whole apparatus was 

 thoroughly exhausted, and pure hydrogen was admitted 

 to approximately 760 mm. pressure. The hydrogen was 

 prepared from the palladium alloy, the first fractions which 

 came off the palladium being rejected, and was dried over 

 phosphorus pentoxide. Every care was taken in the tilling, 



* Communicated by the Physical Society: read March 2, 1000 

 t Proc, Roy. Soc. vol. 1. p. 247. 



