13.2 Dr. Schrocder van dcr Kolk on Gases. 



llegnault found that two thermometers filled respectively with 

 air and carbonic acid ran almost parallel to about 300°; and the 

 same may be assumed, therefore, between 0° and 100°. Since, 

 now, in the case of air, the values of k were known from what 

 has been already said, k could also be calculated for carbonic 

 acid at this temperature.' The value at —87° C. was not calcu- 

 lated, as this is near the point of condensation. 



The following- values were found for k in the case of carbonic 

 acid : — 



Temp. 



Pressure. 



A 



h 



0'76. 1 metre. 2 metres. 



3 1-002050 1-000000 0-991322 



50 1-003736 1-002509 0-997424 



100 1-004488 1-003910 1-001157 



In this case also the differences increase regularly with the pres- 

 sure and with sinking temperature. The above values of &must 

 here be again multiplied by the constant factor K = 19-0949. 



From this the three following formulae of interpolation were 

 calculated : — 



o.n-76 . . *= {i-pew*, |SS}k, 



2m • . *- {1-014466- jjg^}*: 



By differentiation there is obtained, at 0*76 metre, for instance, 



#_ Q ' 294Q1 



dt "(67-03 + ' 

 from which, 



at 3°, ~ =0-000059951 K; 



rile 



at 100°, ~ = 0-000010538 K. 



In the case of nitrogen, the number of EegnauUVs observations 

 is too small for calculating this formula. From the coefficients 

 of expansion observed, it follows that k increases with the tem- 

 perature ; but in what manner k changes with the pressure at 

 100° cannot be determined, owing to a deficiency in the number 

 of determinations of this coefficient under different pressures. 



Now the formulas found for air and carbonic acid show that 

 the values of K for these gases must undergo a small correc- 



