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ME. W. F. G. SWANN ON THE SPECIFIC HEATS OF AIR AND 



of P are given in the adjoining table. The accompanying illustration shows the main 

 portions of the apparatus used in the calibration of the fine tubes, together with 

 several other portions of apparatus used in the calorimetric experiments. The 



cathetometer is shown to the left of the picture ; next to it is the chronograph. To 

 the right of this and behind it are seen the mercury gauge, gas reservoir, and pressure 

 regulator, with the contact breaker in the back ground. To the right of the pressure 

 regulator is the tank containing the tubes, and to the right of this the calorimeter 

 and oil gauge. The arrangement for siphoning water round the jacket of the 

 calorimeter during the calibration may also be seen in the illustration. 



(16) Calculation of the Results. If the gas strictly obeyed the simple gas 

 law over the range of pressure to which it was subjected in the reservoir, the 

 mass Q of gas which flowed through the tubes in any experiment would be simply 

 (PiVi/#i P 2 V 2 /# 2 )/R ; where the suffixes relate to the measurements taken before and 

 after the flow of gas respectively, and R is the gas constant for 1 gr. of gas. Since, 

 however, the gas does not obey the simple law, a correction must be applied. 

 REGNAULT has shown that for air, if p^ = 74 cm. and p 2 = 148 cm. (which represents 

 the range of pressure employed in the present experiments), then at constant 



