178 



Dr. J. P. Kuenen on the Condensation and Critical 

 Table II. 

 Ethane. (April 1895.) 1st sample. 



t. 



Pb- 



Pe- 



5-85 



27-38 



2792 



10-65 



30-45 



3111 



154 



33-84 



34-48 



22-4 



39 73 



40-25 



29 35 



45-94 



4625 



31-0 



4764 



47-95 



3195 



48-81 C 



Table III. 

 Ethane. (April 1895.) 2nd sample. 



t. 



Pb- 



Pe- 



395 



26-17 



2689 



15-4 



34-11 



34-66 



22-4 



39-89 



40-32 



29 3 



45-89 



4619 



32-05 



48-91 C 



9. Tables II. and III. contain values obtained for two 

 samples of ethane on a former occasion. The pressures as 

 shown by a comparison of the p-t curves are this time slightly 

 lower and the critical temperature a little higher. Absolutely 

 pure ethane would probably have pressures slightly lower 

 even and a slightly higher critical temperature. The p-t 

 curves in the diagrams for ethane and the other single 

 substances are drawn with p b ; as this value is probably nearer 

 the true value of p than p e . 



B. Mixtures of Carbonic Acid and Acetylene. 



10. In my former paper I gave a first instance of mixtures 

 having critical temperatures below those for the compo- 

 nent substances. The only instance of critical temperatures 

 above those of the components seemed to be that of mixtures 

 of carbonic acid and acetylene. According to an observation 

 of Dewar's *, a mixture of \ C0 2 and A 2 H 2 has a critical 

 temperature of 41° C, those for carbonic acid and acetylene 

 being 31° and 37° respectively. It seemed necessary to try 

 the experiment, because experiments on mixtures have always 

 to be accepted with caution, unless it appears that exceptional 



* Proc. E. S. of L. xxx. p. 542, 



