Mar. 30, 1888.] 



SCIENTIFIC NEWS. 



293 



ARTIFICIAL RUBIES. 



THE ruby, the corundum of mineralogists is, from a 

 chemical point of view, simply crystallised alumina. 

 Hence, to obtain rubies, we have to crystallise alumina, 

 but this is a problem much more difficult than it may 

 seem at first sight. Several chemists, such as Gandin, 

 Ebelmen, H. Deville, Caron, Debray, and some others, 

 have previously obtained corundum, but merely in the 

 form of a powder. 



In 1 87 7 MM. Fremy and Feil succeeded in producing 

 small crystalline rubies. In 1877 M. Fremy resumed his 

 experiments in concert with a young chemist namet^ v^er- 

 neuil, and he soon effected great improvemen*^ in the 

 process of crystallising alumina. 



On February 27th last, MM. Fr(;my and Verneuil, 



they line the interior of geodes. It is curious, on 

 breaking up this mass, to see the rubies, with their 

 beautiful rose-red colour, appearing among the white 

 material in which they have been formed. 



M. Des Cloizeaux, the eminent crystallographer, has 

 examined these artificial rubies, and declares that they 

 display exactly the form of the natural jewels. 



The separation of the rubies from the gangue presents 

 nc difficulty. It is sufficient to drop the product of the 

 v;alcination into a bottle of water, and shake it briskly. 

 The gangue remains in suspension in the water, whilst 

 the rubies, being heavier, sink to the bottom, and need 

 no treatment with acids. Their crystalline iorm is 

 regular, their lustre is adamantine, their colour beautiful, 

 and their transparence perfect. They have the hardness 

 of the natural stone, and easily scratch the topaz. Like 



—Artificial Rubies in iHtJK Ganc 

 Magnified Twenty Diameters. 





- ■■..■• 







SI''- '^ : '= -v. 



Fig. 2. 



-Crystalline Forms of Artificial Rubies. 

 Magnified Thirty-five Diameters. 



after further experiments, submitted to the Academy of 

 Sciences rubies in rhombohedric crystals, obtained in a 

 regular manner by the action of certain fluorides upon 

 alumina. 



Their method consists in causing fluorides, and 

 especially barium fluoride, to react at a red heat 

 upon alumina containing traces of potassium bichromate, 

 which supplies the colouring matter. The regularity of 

 crystallisation, attained after many trials, is especially due 

 to the regulation of the fire, which determines and modi- 

 fies the chemical reaction. 



These crystals are very different from the specimens 

 exhibited in 1877. The latter were thin, laminar, and 

 friable, and had been formed in a vitreous gangue, which 

 rendered their purification almost impossible. Thus, on 

 analysis, their composition was not constant. In the 

 recent experiments the crystals are formed, not in a 

 vitreous mass, but in a porous and friable gangue, where 



natural rubies, they turn black on heating, and resume 

 their red colour on cooling. 



The accompanying illustrations, from ourcontemporary, 

 La Nature, show the forms of these rubies. 



ACCLIMATISATION.— I. 



WE often hear of the Societe d Acclimatisation, of Paris, 

 and of its gardens, which contain now a more 

 interesting collection of animals than does the time- 

 honoured Jardin des Plantes. 



In these gardens a number of very important experi- 

 ments in hybridisation and in the education of animals 

 have been performed. But the original object of the 

 Society was simply to introduce into France animals 

 which- were natives of other and different climates. 

 Thus the inelegant word acclimatisation has in common 



