176 Foreign and Miscellaneous Intelligence. 



present, unknown, but unfortunately throws doubt upon both 

 processes*. 



11. ON THE CRYSTALLIZATION OF GOLD. (Professor Henslow, of 

 Cambridge.) 



A small glass-stoppered phial, containing a solution of gold in a mix- 

 ture of nitric and muriatic acids, had stood long neglected for a 

 considerable time (perhaps four or five years) in a cupboard. Upon 

 accidentally discovering it, I found a portion of the acid had escaped 

 and the gold crystallized. This effect had probably been promoted 

 by a flaw in the phial, which extended through the neck, and a little 

 way down its length. The stopper, in consequence, must have been 

 slightly loosened, and thus allowed more space for the formation of 

 a thin dendritic crystallization of the gold. This was further con- 

 tinued down the inner surface of the phial, and was there sufficiently 

 thick to admit the impression of minute but distinct crystalline 

 facets. A small crystallized lump of gold lay at the bottom of the 

 phial, but I believe this had been originally attached to the rest, and 

 merely fallen by its weight, as I have since observed to be the case 

 in another portion. Around the stopper, and along the flaw, there 

 was a saline concretion, which tasted like sal ammoniac, and as 

 ammonia was kept in the same cupboard, it had probably united 

 with the muriatic acid as it exuded. Upon finding this specimen, I 

 examined some other metallic solutions, and found a similar separa- 

 tion of the metal had taken place, in a phial containing a solution 

 of platina, and in another containing a solution of palladium. In 

 both these cases a thin, interrupted, and dendritic lamina of metal 

 might be seen between the stopper and the neck, but the crystalliza- 

 tion had proceeded no further. I unstoppered the phial containing 

 the platina, and the lamina (as might have been expected) imme- 

 diately disappeared in the form of a slight muddy film. The palla- 

 dium I still possess. Probably this phenomenon maybe of frequent 

 occurrence ; but as the separation of the metal does not often extend 

 below the neck of the phial, it may have passed unnoticed. These 

 facts, if multiplied, may perhaps serve to throw some light upon the 

 mode in which the dendritic laminae of native gold, silver, &c., are 

 formed in rocks f. 



It would have been satisfactory to know whether, in the case de- 

 scribed by Professor Henslow, any lard, wax, or lubricating matter 

 had been originally applied to the stopper of the phials, which could 

 have caused or promoted the effect of reduction. The Professor 

 has not before met with any cases of reduction in the crystalline 

 form of gold from solution in acid. These, however, are not uncom- 

 mon. We have specimens of gold finely crystallized, by gradual 

 reduction and deposition, from an ethereal solution of its chloride ; 

 and both gold and silver, and also other metals, may be reduced 



Aunalen der Physik, xv. ; 145. f Mag. Nat. Hist. i. ; 146. 



