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PROCEEDINGS OF THE AMERICAN ACADEMY. 



should be so much greater than that produced by the latter (because the 

 affinity-pressure must be already so great) that usually the former alone 

 would be expected to become manifest by its effect. Data illustrating 

 these inferences are given below. 



Another property, going hand in hand with this relation of compressi- 

 bility and boiling point, is density. It is to be expected that of two 

 similar substances, that with the higher boiling point and the less com- 

 pressibility, being subject to greater internal pressure, should be the more 

 dense. 



A few figures, representing several classes of compounds, are given 

 below to show that in general these considerations are supported by fact. 



Kelatiox between Boiling Points, Densities, and Compressibilities 



of Isomeric Compounds. 



In each of these cases, the higher boiling point accompanies greater 

 density and less compressibility. The last-named property has been 

 determined in so few cases that the material for generalization is small ; 

 but as far as they go the data all point in the same direction.* On the 

 other hand, so many densities have been determined that the usual paral- 

 lelism of this property with the boiling point is easily verified. Among 



* Gartenmeister Liebig's Annalen, 233, 309 (1886), found that esters with high- 

 est boiling point have the least coefficient of expansion — a property that very 

 usually varies in the same direction as compressibility. 



