Page:The Journal of geology (IA journalofgeology11893univers).pdf/354

This page has been proofread, but needs to be validated.
776
THE JOURNAL OF GEOLOGY.

Thus I have tried to show, that "Soret's principle" cannot be applied to magmas, and consequently, if magmatic differentiation were a process of molecular diffusion it could not be explained. And it seems to me to be going too far to apply the laws of dilute solutions to magmas before having attempted to consider them simply as mixtures of liquids.

As an illustration of the conduct of two liquids when mixed, let us take aniline and water. If they are mixed at ordinary temperature, when equilibrium is established two layers are formed, one containing 1 per cent. of aniline and 99 water, the other 98 aniline and 2 water.[1] But if they are mixed at 100° the two layers formed will contain 4 aniline and 96 water, and 91 aniline and 9 water; at 150° the proportions are 14 aniline and 86 water, and 76 aniline and 24 water; at 160° they are 25 aniline, 75 water, and 68 aniline, 32 water, and at 166° the two layers should have the same composition, being consequently identical. Therefore, above 166° aniline and water mix in all proportions, but below this temperature the reciprocal dissolving capacity is limited and generally a separation into two layers takes place, the composition of which is a function of the temperature.

This seems to be common for all liquid-mixtures where no chemical action takes place. For all such mixtures there exists a temperature, above which they mix in all proportions. It is true that this temperature is known only for a few combinations of liquids, but it must be regarded as certain that it exists, and if not below then at the critical temperature, because here the capacity of mixing in all proportions is a general property of the gases.

On the other hand, there are certain fluids, which at ordinary temperature dissolve one another without limit, and for these the temperature below which the dissolving capacity is limited is yet to be determined, but in some cases this may not be reached before the transition into the solid form takes place. For us the principal question now is, can we assume that all the chemical

  1. ↑ The numbers given are obtained by interpolation in the curve of Alexejew in Wiedemann's Annalen, 29, table 3. (1886).
This article is issued from Wikisource. The text is available under Creative Commons Attribution-Share Alike 4.0 unless otherwise noted. Additional terms may apply for the media files.