202 ANNUAL OF SCIENTIFIC DISCOVERY. 



fuses and dissolves the alumina. The continued action of heat partly 

 evaporates this sulphuret of potassium, and the alumina separates in 

 the form of little crystals. On opening the crucible, a black mass, 

 sparkling with brilliant points, is found in it, which consists of sulphu- 

 ret of potassium, mixed with crystals of alumina. This mass is after- 

 ward placed in diluted nitro-liydrochloric acid, which dissolves the 

 sulphuret, and lets fall the crystals of alumina to the bottom of the 

 vessel, where they appear as a coarse powder, and, seen through a 

 microscope, have an exact resemblance in form to the natural precious 

 stones. By using a larger crucible, and exposing it to the action of 

 the fire for a longer period, M. Gaudin produced crystals of much 

 greater dimensions, which, upon examination, proved to be true white 

 sapphires, and were even superior in hardness to the rubies ordinarily 

 used for the jewelling of watches. He endeavored to produce colored 

 crystals by the addition of metallic oxides, but found that these were 

 invariably reduced into metals by the action of the charcoal. The 

 successful result of this experiment encourages us to hope that at a 

 future period M. Gaudin, or some one else possessed of his indomitable 

 perseverance, may discover some substance capable of dissolving carbon 

 in a similar manner to that in which sulphuret of potassium has been 

 found to dissob-c alumina, by which the problem of the artificial pro- 

 duction of that beautiful and valuable stone, the diamond, will at 

 length be solved. 



Although not belonging strictly to the subject of the artificial pro- 

 duction of precious stones, it will not, perhaps, be thought inappro- 

 priate to notice some experiments undertaken by Messrs. Deville and 

 Wbhler, which resulted in the discovery of a crystal strongly resem- 

 bling the diamond in its hardness and properties, although of a differ- 

 ent composition. This crystal is that of a substance called boron, 

 which attracted the attention of Messrs. Deville and Wb'hler, on 

 account of its resemblance to carbon. It occurred to these gentlemen 

 that a substance having such a great similarity to the element of 

 which the diamond is composed, would, in all probability, if crystal- 

 lized, have some characteristics in common with that gem. They 

 therefore set to work to find some process which would enable them to 

 reduce it to the crystalline form. 



Boron is only found in nature in combination with oxygen, as 

 boracic acid, and in union with soda, as borax ; and it had, up to this 

 time, been obtained from these combinations only in the form of a 

 brownish green powder, insoluble in water, possessing many of the 

 properties of carbon. It was reserved for the two chemists whose 

 names are given above to produce it in a form hitherto unknown, by 

 the following process : 



In a crucible, lined with animal charcoal, are placed eighty grains 

 of aluminum, and one hundred grains of boracic acid. This crucible 

 is then exposed for five hours to an intense heat, which causes a por- 

 tion of the boracic acid to part with its oxygen to the aluminum. 

 After it has been taken from the furnace and allowed to cool, it is 

 found to contain a sort of glass composed of the remainder of the 

 boracic acid and of the alumina formed during the process of heating, 

 and underneath this a gray metallic mass, sparkling with crystals. 

 This mass consists of merely boron imbedded in aluminum. To sep- 



