332 



Mr. W. Hibbert on the Gladstone 



rises. 



Consequently the high value now found for the volume 

 of the water molecule, as measured by /3, appears to be 

 another indication of its greater molecular complexity, and 

 the fall towards normal value as boiling-point is approached 

 points to a molecular simplification as indicated by the other 

 methods. 



Somewhat similar, though more erratic, is the available 

 evidence with regard to other liquids of known molecular 

 complexity, such as the alcohols and acetic acid. The figures 

 are not now quoted, as they must be redetermined with 

 greater accuracy and perfect exclusion of atmospheric 

 moisture during the experiments. 



We may now test the value of /3 in another way. It has 

 already been mentioned that the ordinary Gladstone expres- 

 sion fails to deal with the transition from liquid to gas, and 

 the suggestion is now made that the discrepancy is due to the 

 neglect of the volume of the particles, a quantity which 

 practically vanishes in the case of vapours. 



The question arises, will the value of /3 deduced from a 

 liquid bring the liquid and gaseous numbers into agreement ? 

 Not many observations are available for this comparison. 

 Obviously the same specimen ought to serve for the liquid 

 and vapour. The work of Lorenz* and Prytz almost exhausts 

 the published data of this sort. 



Lorenz gives two observations on the liquid at different tem- 

 peratures, and also an observation on the vapour formed by 

 the liquid. Unfortunately Lorenz selected the temperatures 

 of 10° and 20° C. for the observations on the liquids, which 

 are too near one another to afford a very satisfactory basis for 

 calculating j3. Notwithstanding this, the results as shown in 

 the following table are very encouraging. 



Substance. 



Temp. 



Specific Refraction 



j3 calcu- 

 lated 

 from 



Liquid. 



Specific Refraction 

 (^-1)^-/3). 



Liquid. 



Vapour. 



Liquid. 



Vapour. 



Carbon Disulphido ... 

 Chloroform 



o 

 10 

 20 

 10 

 20 

 10 

 20 

 10 

 20 

 10 

 20 



•4889 

 •4882 

 •2979 

 •2975 

 •2634 

 •2629 

 •4148 

 •4147 

 •4905 

 •4900 



f -4289 

 f -2681 

 } -2334 

 }-401 

 ] -4561 



0886 



0-0672 



00685 



0030 



0-098 



•4334 



•2677 

 •2282 

 •4035 

 •4554 



•4289 



•2681 



•2334 



•401 



•4561 





Ethyl Iodide 



Ethyl Acetate 



Ethyl Ether 







* Wied. Ann. 1880. 



