It was pointed out that the application of the concept of the partial molar volume to a non-ideal solution such as glass lead to erroneous results.
When the partial molar volume of component molecules will be discussed in connection with their structures, the continuity of partial molar volume must be discarded and the increment of molar volume of a solution must be expressed through equations which contain not only partial molar volumes but also their increments with molarity, owing to the fact that the change of molarity can not be made infinitely small. As an immediate consequence of these results, partial molar volumes of component molecules vary independently with each other as their molarities are changed.
Because of the complicated nature of the change of partial molar volumes with composition in case of non-ideal solutions, it will be worthwhile for such solutions to be converted into ideal solutions through an appropriate selection of complex groups of these solutions as their components.
After such conversion it will become easy to get the value for partial molar volumes which has meanings for estimation of structures of components.
Two examples of this conversion method, each for a chalcogenide glass and for an alkali-borate glass, are shown with good results.