604 PROCEEDINGS OF THE AMERICAN ACADEMY. 



(3) It is pointed out that a given change in chemical energy produces 

 a smaller change of volume than the same change of cohesive energy 

 produces. 



(4) These typical facts are explained by the assumption that both 

 chemical affinity and cohesive attraction exert a compressing effect upon 

 solid or liquid substance, and that the chemically tied part of each atom 

 is more compressed than that which is subject only to cohesive pressure. 



(5) Polymerization and crystallization are shown to be capable of 

 causing irregularities. The cases of water and tin are discussed in detail 

 as types, and it is shown that there is nothing in these cases contradictory 

 to the explanation given above. 



(6) From the comparison of many isomeric organic compounds, it is 

 shown that the explanation covers also their relations of densities, com- 

 pressibilities, and boiling points, including even some of the apparent 

 irregularities in those relations. Thus is shown the reason why additive 

 molecular volumes are obtained only when, of two liquids, the less vola- 

 tile (i. e. the more cohesive) is heated to a higher temperature. 



(7) It is suggested that these varying intensities of internal pressure 

 are adequate to explain the variety of other physical properties, such as 

 tenacity and malleability. 



(8) These considerations, by accounting numerically in detail for most 

 of the irregularities in the more obvious facts discussed in previous papers, 

 afford increased evidence as to the significance of changing atomic vol- 

 ume, and increased support for the theory of compressible atoms. 



Cambridge, Mass. 

 January 25, 1'jOl. 



