It is often taught that gneisses are the further stages of the crystallization of schists and belong to a deeper zone where the pressures and the temperatures were greater.
In length; with such coils, and a sufficient annular space in the pan free from obstruction, in order to allow a natural down-current of the cooking mass, while an up-current all round is also naturally produced by the action of the heated worms or coils, rapid evaporation and crystallization can be obtained, without any mechanical adjuncts to require attention or afford excuse for negligence.
In France the crystallization of soda is performed not in large tanks but in sheet-iron dishes holding only about 4 cwt., and requires only from 27 to 48 hours in the cool season; it is not carried on at all in warmer climates during the summer months.
By advancing crystallization and increased size of their components, slates pass gradually into phyllites, which consist also of quartz, muscovite and chlorite.
Rosenkranz, who in his work Hegel's Naturphilosophie seeks to develop Hegel's idea of an earthorganism in the light of modern science, recognizing in crystallization the morphological element.
Semi-opacity due to crystallization may be induced in many glasses by maintaining them for a long period at a.
The crystallization proper lasts one hour, the working of a charge four hours, six charges being run in twenty-four hours.
In certain districts, notably in the Straits Settlements, syrup is prepared as described above for crystallization in a vacuum pan, but instead of being cooked in vacuo it is slowly boiled up in open double-bottom pans.
It is not necessary that there should be present sufficient water to dissolve the whole of the reacting substance at any one time; it is sufficient if there is enough for hydration and a small surplus for the crystallization by successive stages as above described.
This theory being accepted, it is evident that a small quantity of water, by successive dissolution and deposition of a substance capable of existing in a more soluble and in a less soluble form, is able to bring about the crystallization of an indefinitely large quantit y of material.