80 



Note on the Artificial Production 

 of Crystallised Atacamite. 



By T. C. Cloud, Assoc. Eoy. Sell. Mines, F.C.S., &c. 



[Communicated by the President.] 



It is well known to chemists that the hydrous oxychloride of 

 copper is produced when oxide of copper is acted upon under 

 favourable conditions by certain soluble chlorides, notably 

 those of ammonia and sodium, but hitherto the attempt to 

 obtain this substance in the form of definite crystals has not 

 been successful. I have, however, to record the conditions 

 under which I have found this substance produced. At. the 

 Wallaroo Smelting Works there are large underground culverts 

 connecting the various smelting furnaces with the stack. From 

 certain of these furnaces a substance is produced which deposits 

 in the culvert. This culvert-deposit consists almost entirely of 

 cupric oxide, with a small proportion of an hydrous cupric 

 sulphate. At one part of the culvert there is a small, but con- 

 stant infiltration of seawater, which in contact with the culvert- 

 deposit above described, and under the influence of the high 

 temperature necessarily existing in such a culvert, has in the 

 course of not more than twelve months produced the hydrous 

 oxychloride of copper in a crystalline condition. 



The crystals were found between separated layers of the 

 culvert-deposit, which at this point of the culvert was almost 

 entirely converted into a massive hydrous oxychloride of copper. 

 The crystals were not large, the largest being about one- 

 twentieth of an inch, in diameter. An examination of these 

 under the microscope showed that the crystalline form was a 

 combination of rhombic, prism, pyramid, pinaeoid, and domes ; 

 in fact, the exact form of Atacamite. 



The colour was rather lighter than most specimens of the 

 natural mineral that I have met with. A chemical examination 

 was not made, as it was found practically impossible to obtain 

 a sufficient quantity of the crystals free from the massive 

 deposit upon which they were formed, and as this portion con- 

 tained a quantity of more or less unaltered deposit, its presence 

 in the sample taken for analysis Avould have vitiated the result. 



Having due regard, however, to the conditions under which 

 this substance was formed, and also to its appearance and 

 crystalline character, I think I am justified in stating that we 

 have here an instance of the artificial formation of crystallised 

 Atacamite. 



