By this method it is shown that water, when present as " water of crystallization," behaves as if it were ice.
Glauber's salt readily forms supersaturated solutions, in which crystallization takes place suddenly when a crystal of the salt is thrown in; the same effect is obtained by exposure to the air or by touching the solution with a glass rod.
By advancing crystallization and increased size of their components, slates pass gradually into phyllites, which consist also of quartz, muscovite and chlorite.
This figure afforded, as it were, a new point of crystallization for the existing Gnostic ideas, which now grouped themselves round this point in all their manifold diversity.
Lehmann it melts at 168° (or at a slightly lower temperature in its water of crystallization) and on cooling forms optically isotropic crystals; at 125.6° the mass becomes doubly refracting, and from a solution rhombohedral (optically uniaxial) crystals are deposited; by further cooling acicular rhombic crystals are produced at 82.8°, and at 32.4° other rhombic forms are obtained, identical with the product obtained by crystallizing at ordinary temperatures.
The inactive mixture may be resolved into its active components by fractional crystallization of the cinchonine salt, when the salt of the dextro modification separates first; or the ammonium salt may be fermented by Penicillium glaucum, when the laevo form is destroyed and the dextro form remains untouched; on the other' hand, Saccharomyces ellipsoideus destroys the dextro form, but does not touch the laevo form.
The corresponding changes in the case of the mixture Tuvw are easily understood - the first halt at U, due to the crystallization of pure B, will probably occur at a different temperature, but the second halt, due to the simultaneous crystallization of A and B, will always occur at the same temperature whatever the composition of the mixture.
Gaston Paris, belongs to the very earliest stage of Arthurian tradition, long antedating the crystallization of such tradition into literary form.
The filtrate on cooling deposits crystals of potassium zirconofluoride, K 2 ZrF 6, which are purified by crystallization from hot water.
The heat at which the syrup boils in the clarifiers, 220° F., has the property of separating a great deal of the gum still remaining in it, and thus cleansing the solution of sugar and water for crystallization in the vacuum pans; and if after skimming the syrup is run into separators or subsiders of any description, and allowed to settle down and cool before being drawn into the vacuum pan for crystallization, this cleansing process will be more thorough and the quality of the final product will be improved.
When centrifugals were adopted for purging the whole crop (they had long been used for curing the second or third sugars), the system then obtaining of running the sugar into wagons or coolers, which was necessary for the second and third sugars' cooked only to string point, was continued, but latterly " crystallization in movement, a development of the system which forty years ago or more existed in refineries and in Cuba, has come into general use, and with great advantage, especially where proprietors have been able to erect appropriate buildings and machinery for carrying out the system efficiently.
The salt melts in its water of crystallization at 75°, and the liquid thus obtained goes up to a density of 3.6.
It crystallizes in prisms, which lose their water of crystallization at 160° C. The tellurates of the alkali metals are more or less soluble in water, those of the other metals being very sparingly or almost insoluble in water.
The caesium and rubidium are separated from this by repeated fractional crystallization of their double platinum chlorides, which are much less soluble in water than those of the other alkali metals (R.
Cleavage is thus a superinduced structure, and its explanation is to be found in the rearrangement of the minerals, and the development of a certain degree of crystallization by pressure acting on the rock.
Chemie, 1885, 6, 477) into two components (known respectively as neodymium and praseodymium) by repeated fractional crystallization of the double nitrate of ammonium and didymium in nitric acid.
With the crystallization of the feudal system in the 12th century the office of vidame, like that of avoue, had become an hereditary fief.
Rend., 1904 seq.) by fractional crystallization of the nickel double nitrates, the ethyl sulphates, and the bismuth double nitrates of the terbium earths.
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.
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.
The impurities occasionally present in commercial citric acid are salts of potassium and sodium, traces of iron, lead and copper derived from the vessels used for its evaporation and crystallization, and free sulphuric, tartaric and even oxalic acid.
All these are strikingly alike in appearance and general characters, differing essentially only in chemical composition, and it would seem better to reserve the name cerargyrite for the whole group, using the names chlorargyrite (AgC1), embolite (Ag(Cl, Bl)), bromargyrite (AgBr) and iodembolite (Ag(C1, Br, I)) for the different isomorphous members of the group. They are cubic in crystallization, with the cube and the octahedron as prominent forms, but crystals are small and usually indistinct; there is no cleavage.
In the separation of the constituents of the complex mixture of oxides obtained from the " rare earth " minerals, the methods generally forced upon chemists are those of fractional precipitation or crystallization; the striking resemblances of the compounds of these elements rarely admitting of a complete separation by simple precipitation and filtration.
Moisture is evolved from substances containing water of crystallization or decomposed hydrates.
When precipitated from solutions it forms red tetragonal crystals, which, on careful heating, give a yellow rhombic form, also obtained by crystallization from the fused substance, or by sublimation.
In the case of separation from solutions, either by crystallization or by precipitation by double decomposition, the temperature, the concentration of the solution, and the presence of other ions may modify the form obtained.
The oxides are then converted into double sulphates which are separated from each other by repeated fractional crystallization or by fractional precipitation with ammonia or some other base.
Another type of incipient crystallization which is excessively common in obsidian is spherulites, or small rounded bodies which have a radiating fibrous structure.
Window glass exposed to alkaline vapours often shows a thin iridescent surface film which is supposed to be due to crystallization; the same change is found in pieces of Roman glass which have been dug out of the ruins of Pompeii.
The crystallization proper lasts one hour, the working of a charge four hours, six charges being run in twenty-four hours.
PHENANTHRENE, C14H10, a hydrocarbon isomeric with anthracene, with which it occurs in the fraction of the coal tar distillate boiling between 270°-400° C. It may be separated from the anthracene oil by repeated fractional distillation, followed by fractional crystallization from alcohol (anthracene being the less soluble), and finally purified by oxidizing any residual anthracene with potassium bichromate and sulphuric acid (R.
It is purified by redissolving and crystallization, and is sold either in the state of crystals or finely ground.
The salt crystallizes with varying quantities of water, according to the temperature at which crystallization is effected: between - 4° C. and +6° C. with 7H 2 O, between 15° C. and 20° C. with 5H 2 O, and between 25° C. and 31° C, with 4H 2 O.
In either case the two hydrocarbons are finally separated by fractional crystallization of their picrates, which are then decomposed by ammonia.
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.
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.
A slight degree of acidity seems more favourable to the crystallization of salt than alkalinity; thus it is a practice to add a certain amount of alum, 2 to 12 lb per pan of brine, especially when, as in fishery salt, fine crystals are required.
The acid has been synthesized, as has also the inactive form of methylethylacetic acid; this modification is split into its optical antipodes by crystallization of its brucine salt.
If, however, a solution be cooled slowly past its saturation point with no solid present, crystallization does not occur till some lower temperature is reached.
Hence the conditions necessary to secure equilibrium when the solid phase is present are not the same as those necessary to cause crystallization to start in a number of crystals at first excessively minute in size.
From this and other evidence it has been shown that the first thin shower in open vessels is produced by the accidental presence of tiny crystals obtained from the dust of the air, while the second dense shower marks the point of spontaneous crystallization, where the decrease in total available energy caused by solidification becomes greater than the increase due to the large surface of contact between the liquid and the potentially existing multitudinous small crystals of the shower.
In practical cases of crystallization in nature, it is probable that these phenomena of supersaturation often occur.