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LXXII.— AETIFICIALLY-PEODUCED GOLD CEYSTALS. BY 

 WILLIAM N. ALLEN. 



[Kead, December, 15, 1884.] 



GrOLD crystals are occasionally found native ; the occurrence, how- 

 ever, of the crystalline metal in the laboratory has, as far as I can 

 find, not yet been published. 



The crystals which are microscopic were deposited by a neutral 

 solution of chloride of gold and sodium, and appear as regular 

 three- or six-sided tables perfectly crystalline in structure ; the 

 forms are those of octahedra, the largest observed being y^-o inch 

 in diameter. 



Many present surface-markings, of which I exhibit a good 

 example ; there is considerable difficulty in obtaining definition, 

 owing to the great surface reflection. 



With a very oblique light, it can be observed that the edges 

 present a bevelling, the reflection being such as would be given by 

 crystals having the forms figured in MuspraWs Chemistry, vol. ii., 

 p. 265. 



The only note I find which refers to gold separating in laminae 

 from solution has been kindly given me by Mr. E.. J. Moss, f.c.s. 

 It is from a work by M. Golfier Bessayer, Annales de Chimie et de 

 Physique, published in 1832, in which it is stated that a solution of 

 gold chloride, prepared with as little acid as possible, and which 

 was laid aside for some time, then contained a quantity of small and 

 very brilliant spangles (pailletes) of gold, the author apparently 

 did not recognize them as crystals. 



The word " spangle " is used by Fresenius in his Qualitative 

 Analysis, 8th ed., p. 144 ; but the spangles of gold obtained as 

 directed by him do not present crystalline structure. 



In connexion with this subject, I exhibit copper crystals de- 

 posited in a mixture of cupric sulphate, treacle and vinegar ; the 

 forms are similar to those of the gold crystals, and to those of 

 copper, which occur in the well-known " Aventurine glass." 



