Dr. Schroeder van dcr Kolk on Gases, 127 



v i T i 

 The proportion of the volumes of an ideal gas is thus like that 

 of hydrogen. 



Thus, in the case of hydrogen as in the case of an ideal gas, k 

 must be regarded as independent of the temperature; with hy- 

 drogen, indeed, k changes with the pressure; but this is without 

 influence in the present case, in which the pressure is constant. 

 For measuring the temperatures, let us suppose a thermometer 

 filled with hydrogen, in which the gas expands under constant 

 pressure, which is first immersed in boiling water and then in 

 melting snow, and between these points is divided into 100 equal 

 parts. Each part will represent a degree of the scale taken in the 

 sequel as the basis in calculation. 



It is easily seen that the indications of this thermometer will 

 be perfectly like those of one filled with an ideal gas. 



Taking the coefficient of expansion =0*3661, we obtain for 

 the absolute zero —273°- 15. 



For calculating k under different pressures, there was obtained 

 in the case of hydrogen 



'hich 



k h = \i+A(h-l)+B(h-l)*\K, 



A= 0-00038969, 



B = 0-000039831, 



K= 422-337. 



The volume of 1 kilog. at 0° and 0*760 metre pressure at 

 Paris 



= 11-16346 cubic metres. 



In so far as k, in virtue of Regnault's results, can be considered 

 to be independent of the temperature, this formula is valid for 

 all temperatures. 



In the case of air at 4°, the formula was obtained, 



^=[l-A(/*-l)+B(/*-l) 2 ]K, 



A= 000124351, 



B = 00000229842, 



K = 29-2443*. 



The volume of 1 kilog. at 0° C. and 0-760 metre pressure 

 = 0-773283 cubic metre. At 100° the formula was obtained, 



k™= [1-00062-0-000111 {h- 1)]K. 



* This value, as well as that for carbonic acid, is somewhat different 

 from the one already given, as will be shown in the next paragraph. 



