Crystallization

“ For example, let the effect a be crystallization. We compare instances in which bodies are known to assume crystalline structure, but which have no other point of agreement; and we find them to have one, and as far as we can observe, only one, antecedent in common: the deposition of a solid matter from a liquid state, either a state of fusion or of solution. We conclude, therefore, that the solidification of a substance from a liquid state is an invariable antecedent of its crystallization. ”

“ Although the phenomenon of crystallization does not essentially depend upon temperature, but rather upon the relative quantity of liquid that holds the substance in solution, it will be conceived that a moment will arrive when, the liquid having evaporated, the atmospheres will be close enough to each other to attract each other and become polarized and symmetrically juxtaposed, and, in a word, to crystallize. ”

“ When a lava is cooled quickly, the commingled silicates solidify in the diffused condition essentially as they were in the liquid; for there is no time for the silicate molecules of a like kind to come together, particle by particle, in regular systematic order, as required in crystallization. The essential feature of crystallization is this systematic arrangement of the molecules according to a definite plan, giving a specific crystal form, as a cube, a hexagonal prism, etc. ”

“ As light at any spot in the world-space creates a central point, the nucleus of a comet, around which more of the mass of æther is constantly accumulating till it finally coagulates into the solid condition; so does the process of crystallization evoke some particular spot, point or nucleus in the water, wherein the crystallizing forces are excited, which attract the mass that is susceptible of fixation and fashion it into a crystal. The process of crystallization is a process of fixation, and with it also is furnished the theory of crystallization. ”

“ Fig. 28.—Three crystals of sodium chloride in process of formation, each in the centre of a field of crystallization.
Every crystallizable substance gives a different characteristic field of crystallization. In 1903, at the Congress of Angers, I terminated my address by these words: "The field of crystallization may serve to determine the character of a substance in solution." ”

“ When cold, no crystallization occurs until atmospheric air is admitted; and it was formerly believed that the pressure of the air effected this object, until some one thought of the oil, and now the theory is modified, and crystallization is supposed to occur in consequence of the water dissolving some air which causes the deposit of a minute crystal, and this being the turning point, the whole becomes solid. ”

“ But this law of crystallization gives to snow and ice their mechanical properties, and is connected with a multitude of adjustments of water in the solid state to its place in nature. The same law, varied in a vast number of ways in every distinct substance, builds up crystals of all kinds and crystalline rocks, and is connected with countless adaptations of different kinds of matter to mechanical and chemical uses in the arts. ”

“ The forces of which solidity, cohesion, and crystallization are the result, are those which give to minerals their permanent existence and their physical properties; and ever since the discovery of the distinctions of Crystalline Forms and Crystalline Systems, it is certain that this force distinguishes groups of crystals in the most precise and definite manner. The rhombohedral carbonates of lime and of iron, for instance, are distinguished exactly by the angles of their rhombohedrons. ”

“ Crystallization, seen thus in its cosmic aspect, shows a dynamic orientation which is polarically opposite to that of the earth's seismic activities. Just as in the latter we observe levity taking hold of ponderable matter and moving it in a direction opposite to the pull of gravity, so in crystallization we see imponderable matter passing over from levity into gravity. And just as we found in volcanism and related processes a field of activity of 'functional sulphur', so we found in snow-formation and related processes a field of activity of 'functional phosphorus'. ”

“ And those who hold that water of crystallization exists in solution have been entirely oblivious of the fact that, while they are ready to accept the results of the modern science of thermo-chemistry, and to employ them to support their views on hydration, yet these very results, if correct, prove without a shadow of a doubt that water of crystallization does not exist in solution. ”

“ Charcoal is pure carbon in the uncrystallized state, which the magic of crystallization has transformed into the symbol of all that is brilliant and beautiful.
Beauties of Crystallization.
Dissolve alum in hot water until no more can be dissolved in it; place in it a smooth glass rod and a stick of the same size. Next day the stick will be found covered with crystals, but the glass rod will be free from them. In this case the crystals cling to the rough surface of the stick, but have no hold upon the smooth surface of the glass rod. ”

“ By repeating this process, the composition of the successive crops of mixed crystals which are obtained approximates more and more to that of the pure component B, while, on the other hand, the composition of the liquid phase produced tends to that of pure A. By a systematic and methodical repetition of the process of fractional crystallization, therefore, a practically complete separation of the components can be effected; a perfect separation is theoretically impossible. ”

“ Crystallization, whether in a pure or impure solution, will proceed to only a certain extent, and will only partially remove the sucrose from the solution in one boiling, the limit of crystallization being governed by the amount and nature of impurities present. ”

“ The purpose for which crystallization is here introduced, is not to give a specific figure to a particular substance, but to arrange the substances which it has formed and figured, according to certain rules; a work which we know not how it is to perform, and in which we have no experience of its power. Accordingly, this principle does not account, in any way whatever, for the circumstances which attend the inflection of the strata, for the simple curvature which they affect, nor for that parallelism of their layers, which, in all their bendings, is so accurately preserved. ”

“ If he means by this to say, that a precipitation without solution would take place the sooner the more inadequate the menstruum was to dissolve the whole, the proposition may be true; - 181 - but will be of no use to explain the crystallization of minerals, (the very object he has in view,) because to crystallization, it is not a bare subsidence of particles suspended in a fluid, but it is a passage from chemical solution to non-solution, or insolubility, that is required. ”

“ Here again we need none of Vulcan's aid, for we all know that when once crystallization commences each little crystal will have its growth in spite of almost any resistance. Witness the growth of ice crystals in our water pipes in zero weather. In other words, the force exerted by growing crystals is known to be at least of the same order of magnitude as the crushing strength of the grown crystal. ”

“ We can also easily conceive that in certain cases, the peculiar circumstances of which lie equally hid from us, the approximation of the spheres of crystallization may have caused the crystalline polarity of the several masses to interfere with each other, so as to have produced in many cases an irregularity still greater than this, and in some instances even entirely to have obliterated the appearance of central tendencies. ”

“ Upon entering their intimate structure, it orients or groups their atoms, and separates their molecules or brings them together. From this, would it not be surprising if it did not intervene in the wonderful phenomenon of crystallization? Crystallization, in fact, depends upon cohesion, and, in the thermic theory, this force is not distinct from affinity, just as solution and dissociation are not distinct from combination. ”

“ The boy who plays with blue-stone, dissolving it in water and then recovering it again by crystallization, thus doing for fun what the freshman in a chemical laboratory does because he is directed, learns that the crystals will be large or small, few or many, according to the speed with which they form; large and few if they form slowly, small and numerous if they form rapidly. This is equally true of sugar, common salt and other crystalline substances. We see, then, that circumstances as well as substance have to be taken into account. ”

“ They are there, it would seem, for their own sake;—because they are pretty;—symmetry and beauty are there on their own account; or because they are universal adjuncts of the general laws by which the creator works. Or rather we may say, combining different branches of our knowledge, that crystallization is the mark and accompaniment of chemical composition: and that as chemical composition takes place according to definite numbers, so crystalline aggregation takes place according to definite forms. ”

“ Deliquescent crystals may be preserved by placing them, when dry, in naphtha, or any liquor in which they are perfectly insoluble. Some salts, like Glauber's salts, contain so much water of crystallization that when subjected to heat they melt and dissolve in it, and this liquefaction of the solid crystal is called "watery fusion." ”

“ Though it may be necessary that in certain periods everything is brought into flux in order to bring forth new, essential mixtures, and to give rise to a new, more pure crystallization, it is likewise necessary to alleviate this crisis and prevent the total dissolution, so that a core remains, a nucleus that brings together a new mass, and which then constitute beautiful new forms. So, the solid draws itself more tightly together, reducing the excess warmth so that one spares no means to prevent the breaking of bones and dissolution of the typical fibers. ”

“ It is, therefore, not improbable, that crystallization is a species of vegetation, and is accomplished by the same powers to which the growth of plants and animals is to be ascribed. Some kinds of crystallization resemble vegetation so much, that we can scarce avoid attributing them to the same cause. ”

“ And if, in the case of any proposed crystal, we should doubt to which kind the specimen belongs, the measurement of the angles of cleavage would at once decide the question. The principle of Crystallization therefore appears, from analogy, to be exactly fitted to take the place of the principle of organic Generation. The forces which make the individual permanent and its properties definite, here stand in the place of the forces 156 which preserve the race, while individuals are generated and die. ”

“ Crystalline growth may also take place in solid amorphous matter, for example, in the devitrification of glass, and the slow change in metals when subjected to alternating stresses. Beautiful crystals of many substances may be obtained in the laboratory by one or other of these methods, but the most perfectly developed and largest crystals are those of mineral substances found in nature, where crystallization has continued during long periods of time. ”

“ There is a second process, which is now more commonly used than the above, for separating this active substance, that is, the radium, from the barium with which it is always found. It is called the process of fractional crystallization, and consists simply in retaining the first crystals which crystallize out from an active barium chloride solution and then redissolving these crystals and allowing some of them to crystallize out again, and so on. With each new crystallization the activity of the crystals per unit of weight increases. ”

“ We have said that crystals vary in size, and this variety may be traced, in the cases of crystallization from fluids, to the slowness or the rapidity of the cooling process. If the work be done slowly, then the crystals obtain a size commensurate with the time of cooling, as they are deposited one upon the other. The form of minerals is the first important point, and to ascertain their forms and structure we must study Crystallography. ”

“ The reasons why no crystals appear when the evaporation is hastily performed, and carried on to dryness, are, first, that the particles of salt, being always in motion while the solution is hot, have not time to exert their mutual affinities, and to unite together as crystallization requires: Secondly, that a certain quantity of water enters into the very composition of crystals ”

“ One of the most beautiful illustrations of cohesive attraction is seen in crystallization. In every instance in which substances pass into the form of a solid, they tend to assume regular shapes called crystals. Each material has its own characteristic form, so that a crystal is a type of a species in the mineral world, even as a plant or an animal is in the organic kingdom. A crystal is a substance bounded by plain surfaces and symmetrically arranged about imaginary lines called axes. The final form depends upon certain smaller forms in its interior structure. ”

“ An example of this is sugar-candy, of which a single isolated crystal may have grown freely in a solution of sugar. Matter presenting well-defined and regular crystal forms, either as a single crystal or as a group of individual crystals, is said to be crystallized. If, on the other hand, crystallization has taken place about several centres in a confined space, the development of plane surfaces may be prevented, and a crystalline aggregate of differently orientated crystal-individuals results. ”