in the interior of Cupriferous Minerals. I2T 



tals ; but only extensive collections, or the large quantity ga- 

 thered and preserved on the spot, both of which I had the 

 good luck to examine, will allow of observing perfect and con- 

 tinuous passages from one to the other, by means of a series, 

 which may be established of the occurring varieties, and of 

 which these may be considered as the extremes. The series be- 

 gins with such crystals as not only possess the shape of the blue 

 copper, but likewise consist of that substance, with the excep- 

 tion of small particles of the green fibrous malachite, which 

 appear like something foreign, accidentally imbedded in the 

 otherwise homogeneous mass. It terminates in such varieties 

 as scarcely betray the original shape of the hemi-prismatic 

 crystals, the last blue particles having disappeared, and the 

 fibres grown out even beyond the original surface of them, 

 and showing disengaged crystalline terminations. The inter- 

 mediate members distinctly possess the shape of crystals of the 

 blue copper ; nay, they have occasionally even particles of the 

 original substance here and there distributed over their sur- 

 face, which to the last preserve a parallel position. They are 

 not displaced by an increase of bulk of the newly formed spe- 

 cies. The chemical difference between the two is not consi- 

 derable. Several analyses published by Klaproth, Vauquelin, 

 and Phillips, agree very nearly with the formulae proposed 



by Berzelius, which are Cu Aq^ -}- 9> Cu C^ for the blue cop- 

 per, and Cu C -j- Aq for the malachite. The proportions of 



The change effected during the process of decomposition is 

 the loss of a portion of carbonic acid, which is compensated by 

 an additional quantity of water. If the formulae above-men- 

 tioned are resolved into their constituent parts, as given sepa- 

 rately in the analysis, the blue copper is composed of three 

 atoms of oxide of copper, two of water, and four of carbonic 

 acid, while malachite contains three atoms of each. One atom 

 of carbonic acid is therefore exactly replaced by one of water. 



