some Thermodynamical Relations. 517 



It will be seen that these numbers vary between 0*2453 for 

 phosphorus chloride and 0*3240 for ethyl alcohol. The alco- 

 hols, water, and acetic acid give all nearly 0*32 • and benzene, 

 and bodies containing halogens and sulphur give lower num- 

 bers, averaging 0*2564. 



The sequel will show that these numbers cannot be regarded 

 as experimental deviations from a constant ; but that they 

 have significance can hardly be denied. It would also appear 

 that the nature of the element in the compound, and its 

 amount influence the absolute value ; though the nature and 

 extent of this influence can hardly be formulated. 



The second law is : — If the amounts of heat required to 'pro- 

 duce unit increase of volume in the passage from the liquid to 

 the gaseous state be compared at different pressures for any two 

 bodies , then the ratio of the amount at the boiling-point under a 

 pressure p, to the amount at another pressure p 2 , is approxi- 

 mately constant for all liquids. 



Or, at p ly bears a constant proportion to at p 2) 



for all liquids, and probably for all solids. 



In support of this statement the facts to be adduced are as 

 follows : — 



Water. 



Chloroform. 



P. 



T. 



S l-" 5 2- 



L. 



L 



T. 



*1- S 2 



L. 



L 



mms. 





CCS. 





S l-*2 





CCS. 





S L-*2 



300 



76-4 



4022 



552-1 



0-137 



35°0 



535 



64-65 



0121 



760 



100-0 



1695 



536-5 



0-317 



61-0 



229 



61-2 



0-267 



1000 



107-1 



1313 



531-5 



0-405 



693 



178 



60-4 



0-339 



2000 



129-3 



695 



515-6 



0-742 



92-5 



95-3 



58-2 



0-611 



3000 



1433 



479 



505-7 



1-055 



108-5 



66-3 



56-6 



0-854 



4000 



154-2 



369 



4977 



1-350 



1210 



51-4 



55-4 



1079 



5000 



162-8 



301 



491-6 



1-633 



131-0 



421 



54-5 



1-294 



6000 



170-1 



255 



486-1 



1-906 



1400 



35 9 



53-6 



1-493 



7000 



1770 



222 



4813 



2-168 



148-0 



31-4 



52-8 



1-684 



8000 



182-9 



197 



477-0 



2-424 



1550 



27-9 



52-2 



1-871 



The ratios, placing 

 each substance, are : — 



s i — S 2 



at 300 millims. pressure = 1*0 for 



P 300 760 1000 2000 3000 4000 5000 6000 7000 8000 



Water 1-00 2-30 2*94 5'40 7*68 9-81 11*88 1386 15*77 17*63 



Chloroform... l'OO 2-22 2'81 506 7*07 8*94 10*72 12-38 13'96 15*51 



j Phil. Mag. S. 5. Vol. 20. No. 127. Dec. 1885. 



20 



