CARBON DIOXIDE AT DIFFERENT TEMPERATURES. 



221 



temperature _piVi/p 3 V a = 1 '00141 approximately. Hence to correct the values of 

 PV/0 to the values they would have had if the gas had obeyed BOYLE'S law, taking 

 our standard pressure as that due to 76 cm. of mercury, we find that the observed 

 values of PV/0 must be multiplied by l + (0'0014l)(P-76)/74. A further small 

 correction is necessary on account of the departure of the gas from the linear 

 relationship between PV and 6 over the range of temperature from C. up to the 

 temperature of the reservoir, but this may be conveniently applied to the final 

 value of the specific heat. A lengthy series of preliminary observations, full details 

 of which are preserved in the archives, was performed with a set of ten tubes, and 

 practice and experience with the method gained. The agreement in these experi- 

 ments was very satisfactory. The following table is an abridged record of the 

 calibration of the sixteen tubes used in the final experiments, the value 

 0'0012928 gr./c.c. being taken for the density of air at N.T.P. in the calculation of 

 the gas constant B,. The experiments were made to determine how the flow varied 

 with the pressure difference between the ends of the fine tubes (H), the mean 

 pressure in them (P). and their temperature (t) : 



(17) ABRIDGED Table for the Calibration of the Tubes for Air. 



Of course the values of H, P and t were not quite the same in each of the individual 

 experiments from any set in the above table, it was easy, however, by first obtaining 

 a preliminary empirical equation, to reduce the values of Q for any set to the same 

 values of H, P and t. The above values of H, P and t corresponding to the 

 temperature 18 C. are satisfied to 1 part in 10,000 by the equation 



Q = 0-0046489{l-0-0095[P-78]}{ v /(491' 



