Page:Outlines of Physical Chemistry - 1899.djvu/279

 APPENDIX

��ON THE DISSOCIATING ACTION OF OKGANIC

SOLVENTS »

The reader is aware that in most cases a distinction must be drawn between the constitutive particle of a substance and its molecule. The former is often a multiple of the latter, and that not only for solid or liquid 2 substances but also for certain

The solution of a substance is generally accompanied by a dislocation of the molecular groupings, and eventually also by a dissociation of the salt molecules. But, from the point of view both of the isolation of the molecules and of the dissociation of the same, it is not necessary that all solvents should manifest the same degree of activity.

If we estimate this activity from a study of the boilmg or freezing povnts of solutions, the result of the investigation is : Water is the disintegrating agent par excellence ; it not only breaks down almost all substances to simple molecules, but it

��1 This subject might well have been treated of directly after the chapter on the nature of salt solutions. But as it is rather long and detailed it might, at that point, disturb the simplicity and the order of the theoretical statements, and I prefer rather to insert it here as a postscript.

molecular association is very frequent ; in the solid state it is the rule and not the exception.
 * Ramsay and Traube have proved this. In the liquid state

boiling point.
 * Abnormal density of acetic acid at a temperature just above its

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