218 Precious Stones. 



liave been made to revive superstitions of an analogous kind; 

 but without sufficient success to affect questions of price. 



With reference to many of the old stories, we wonder that 

 erroneous belief was not exploded by experiment or observa- 

 tion ; but popular credulity has usually been determined by 

 authority or association, and at the present day very few per- 

 sons are in the habit of rigidly testing the theories they are 

 induced to accept. In Celiinr's time the art of poisoning was 

 carried to a diabolical perfection, but faith was not exclusively 

 put in preparations really competent to produce a lethal re- 

 sult; he himself tells us that he narrowly escaped being 

 poisoned by a pounded diamond, through a needy jeweller 

 having luckily substituted some other stone. He argued that 

 the diamond preserved its angularity in the finest powder, 

 which was not the case with less hard substances, and he took 

 it for granted that the sharp particles of the diamond caused it 

 to stick in the coats of the stomach and thus produce an 

 injury of which the victim died. Such reasoning as this, 

 without experimental verification, would satisfy many persons 

 now, and it has a plausibility about it much greater than was 

 usually needed to satisfy the ancient or mediaeval mind. 



The superstitions connected with precious stones would 

 form an interesting chapter in the mental history of mankind, 

 and in tracing them we should find fancies that were elegant, 

 as well as opinions that were absurd. We may if we please 

 retain the poetry without hostility to science, and let our 

 jewels symbolize the good qualities they were said to confer. 



The chemical composition of precious stones is pretty 

 accurately known; but the mode in which nature produces 

 them is not understood. A destructive analysis, or one which 

 resolves any compound into so-called elements, or substances 

 that have hitherto resisted decomposition, gives no clue to 

 the manner in which it can be re-formed. In some simple 

 cases it is sufficient to bring the elements together, as when 

 a metal like potassium and gas like oxygen form a binary com- 

 pound if simply left in contact for a short space of time. In 

 a great variety of cases, particular compounds can only be 

 produced by indirect methods, and by causing bodies to act 

 upon one another in what is called their nascent state, that 

 is to say, in the condition of activity exhibited at the very 

 moment in which they are separated from a previous combi- 

 nation, or in which they themselves are primarily formed. 



To make precious stones by artificial means we must com- 

 bine their elements as nature has done, or, as in the case of 

 the diamond, arrange their particles in the precise form. 



We know carbon in the dense opaque condition of char- 

 coal, in the transparent gaseous state of carbonic acid, and in 



