( ^7a ) 



Aflrr (lic \n|H)iir noIiiiih's 1i;i\<' IIiiis heen r(.'(liic('(l lo oik^ tcnipc- 

 mluro, llic li(|iii<] noIiiiik'S are (lrri\(Ml IVoiu lliis. Wc liaxc assiiiu('<l 

 ill lliis llial /', aiul /'. are riiiiclioiis ol' llic Iciiiitcraliirc 7' oiilv and 

 nol also ol' r, as Dk IIkkn and ollicrs llunk. ( >ii llns siipposilioii 

 >\ (' call dcrixc i\ and r., IVoiii each pair ol' oI»s(m-\ alioiis of rj;,^ al 

 diJTei-eiit /• and a( llic same Icnipcralnrc. 'Idic values calciilaled llins 

 have heen combined in (able XXI (o.uelher \\i(li ihose derived direclly 

 from observation. 



TABLE XXI. 



Isothermal of 25°.55 C. Isothermal ol 2SM5 C. 



We see that no reuidar variation in the values of i\ and i\^ can 

 be remarked, so that this justifies witli regard to these experiments 

 our assumption of the dependenee of i\ and /•., on the temperature 

 only. 



In the ealciilation of the mean values of i\ and r., in table XXI 

 we have accorded the same weight to the \abie bori'owed directly 

 from obsei-vatioii as to tlie mean of the values deri\ed from the 

 other observations. 



§ 5. For the determination of the eritieal point the following may 

 serve: The thermostat was adjusted at a few hundredths of a degree 

 below the eritieal tem[>eratiire (the temperature abov(> wliieh no 

 statiimary meniseus is observed). Ijy letting a small (|uantity of water 

 of higher temperature into the mi.xing bath, the e.\|»erimental tube 

 was brought to a few hundredths of a degree above the eritieal 

 teni|»erature, and the substanee was well stirred. Tlu'ii Ihe tempe- 

 laliire falls \oi-y slowly. If the volume \\o^ between certain limits, 

 the following phenomena may be seen: A blue mist is formed which 



