CHEMISTRY. 





METHOD OF CRYSTALLIZATION. 



M. FKEMY communicated to the Pans Academy of Sciences a 

 paper on this subject, an abstract of which is given in the "Quar- 

 terly Journal of Science " for January, 1867, as follows** 



" I have thought that if I could slowly effect the precipitations 

 and decompositions which render bodies amorphous, because they 

 are instantaneous,- 1 should place myself in the same conditions as 

 nature, and that I should obtain, in a crystallized state, bodies 

 which instantaneous precipitations rendered amorphous. For 

 this purpose I first introduce two bodies which react on each 

 other in liquids of different densities, containing gum, sugar, or 

 gelatine. Then I separate them by beds or partitions of porous 

 bodies, such as wood, un glazed porcelain, etc., or by leaves of 

 unsized paper, which in imbibing them, little by little, renders the 

 decomposition slow, and nearly always produces crystallized bod- 

 ies. The porous vessels allow the liquid which they contain to 

 run out very slowly, and often produce beautiful crystallizations, 

 which are found in the interior of the vessels when the liquid has 

 left them. I have thus obtained insoluble bodies in a crystallized 

 state, and often of very perfect forms, such as sulphate of barytes, 

 sulphate of strontian, carbonate, borate, and chromate of barytes, 

 magnesia, sulphur, etc. This method appears to me very gener- 

 ally applicable. I have tried to apply it to the alkaline silicates, 

 by submitting them to the action- of certain acids, in porous ves- 

 sels, with the hope" of obtaining quartz or crystallized silica, which 

 is so common in nature. Slowly decomposing, they have formed 

 white crystalline masses hard enough to scratch glass. I hoped to 

 achieve the production of real quartz, but the crystals dissolved 

 in the alkaline liquids, and they were highly hydrated. There 

 were silicates of soda, containing silica 68, soda 5, water 29 ; the 

 proportions of silicate and water being the same as in Si O 3 , 2 II 

 O. These experiments confirm the provisions of our illustrious 

 confrere, M. Chevreul, who, to explain the presence of oxalate of 

 lime in certain plants, supposed that a soluble oxalate slowly trav- 

 ersing the coating of a vegetable cell, or a bundle of fibres, could 

 react on a calcareous salt, found in a cavity, and give birth to 

 crystallized oxalate of lime. 1 believe I can say, in conclusion, 

 that the method which I have published will permit all bodies 

 which are found crystallized to be artificially produced, whether 

 in the earth or in organic tissues, and consequently that it will 

 afford us much useful knowledge respecting their modes of pro- 

 duction.*' 



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