334 



Mr. W. Hibbert on the Gladstone 



For the Centigrade scale the relation indicated seems to 

 approach one of equality. 



There are ten substances for which /3, Vt, and T are known 

 with sufficient (or apparently sufficient) accuracy. The above 

 equation is here used to find the value of /3 from v and T, 

 and the value so obtained is compared with that given by the 

 optical data. 



The following table shows that the results are in fair 

 agreement, if we remember that the three data compared 

 together are mostly due to different observers using different 

 specimens. 



Substance. 



T 



V'T- 



v t +s/t 



j3 from 

 refraction. 



Heptane 



1-629 

 0-818 

 1-146 

 1-282 



1043 



1-044 



0-766 



0-6388 



1-2005 



0-5178 



19-3 

 17-89 

 21-2 

 19 62 



19-34 



201 



20-7 



21-5 



2315 



20-13 



0-084 

 0-0457 

 0-054 

 0065 



0-054 



0-052 

 0-0365 

 003 

 0-052 

 026 



0081 

 00460 

 0-0525 

 0-068 

 f 0-067 9 

 [ 0-060 - 

 0-054 

 0047 

 0045 

 0-068 

 0-031 



Carbon Disulphicle ... 

 Aniline 



Water 



Phenyl Iodide 



Ethyl Cinnamate 



Ethylene Dibromide. . . 



Many other figures might be given but they are of inferior 

 accuracy, and ought not to be placed along with those just 

 quoted. The examples are sufficient to establish a case for 

 further inquiry, inasmuch as the agreement is close enough 

 in six or seven cases to preclude the notion of accidental 

 coincidence. 



If additional data confirm the foregoing result, it affords 

 us another method of calculating the quantity /3 when the 

 boiling-point and the density at that temperature are known. 

 I propose to get /3 for other substances by this method, and 

 test several deductions by the result. It is evident, on general 

 grounds, that values of ft calculated by this method will be 

 of the same order of magnitude as that given by the optical 

 data. All ordinary liquids boil between, say, 50° and 300° 

 Centigrade, or 320° and 470° absolute ; and the square roots 

 range between 18 and 22, with average about 19, which is 

 fairly near the average ratio for vjft. 



It is hardly necessary to point out that this relation may 

 possibly supply a hint as to the unknown law between volume- 

 relationships of liquids and the temperatures. For example, 

 I was tempted to compare the varying value of (3 in the case 

 of water with its very varied coefficient of thermal expansion a. 



