362 THE DIAMOND AND OTHER PRECIOUS STONES. 



of a g■oldo^-TeIlo^Y tiut, covered witli little reddish spots, it is cut like a 

 gem, but is at the present time very little known ; it is called aventurine. 



After the consideration of crystallized minerals in nature, we sbould 

 attempt the imitation of them in the laboratory. I do not mean such 

 imitation as paste and color produces. I refer to the reproduction as 

 nature gives the gems to us, and propose the making of real i^recious 

 stones, such as has been attempted in the case of the diamond. I have 

 already said that Ebelman, at Sevres, has crystallized aluminium and 

 silex thus making a true spineJIa. M. Despretz, in tbe experiments 

 by which he has volatilized charcoal and tbe diamond, has also 

 melted aluminium and silex. He has obtained from these substances 

 little hollow spheres, lined inside witli crystals, like the cavities which 

 are found in mines containing crystals of various kinds. In all the ex- 

 periments of Despretz, the exceedingly intense heat whicb he produced 

 by electricity only served to dissipate the particles of tbe diamond 

 without producing any crystallization. It is therefore evident that the 

 diamond is not an igneous production. Its origin is probably electric; 

 but what was the epoch of its first production from ordhiary carbon, 

 and where did its crystallization begin ? 



According to M. Boutigny, the carbon of the earth comes from 

 showers of hydrogen, united with carbon, which watered as it were the 

 earth when it was too hot to receive ordiuarj^ rains. We have not yet 

 seen the bearing of this hypothesis on the crystallization of the diamond. 

 I have already said that sulphur and carbon, in uniting together, produce" 

 a liquid as limpid as v.-ater or pure alcohol. Now, with this it might 

 be well to try tlie following experiment : Having fdled a strong iron 

 bottle with the liquid, and having covered it with an iron stopper, tirmly 

 screwed into the neck, I would i>lace it in an oven at 200 or 300 degrees 

 centigrade of heat. At this temperature the iron of the bottle and the 

 sulphur would possibly react upon each other and enter into combina- 

 tion. Now, the sulphur, uniting with the iron, would leave the carbon 

 fi-ee, which might thus slowly- arrange itself in the crystalline form. I 

 merely propose this experiment, which might require a long-continued 

 heat of uniibrm temperature, to illustrate the play of chemical affinity. 

 It is possible the effect would be analogous to that which takes place 

 when a porous body is plunged into a saline solution, which absorbs 

 the water and leaves the salt crystallized on its surface. We should 

 inform those who may be tempted to try this experiment, that the 

 fluid within the bottle would acquire by beat an immense repulsive force, 

 suflicient to break almost any vessel inclosing it, especiall}' one of iron, 

 after the metal has been acted on hj sulphur. The old alchemists fre- 

 quently met with serious accidents in their attempts to transmute mer- 

 cury by overheating it in closed iron vessels. 



We have just said that there is very little chance that nature will 

 furnish us with any new minerals. We must therefore depend on the 

 results of the laboratory, and examine every substance whose hardness, 



