157 



Miscellanea. 



[April 



" Collecting together the results of the above operations, we have 



the folio win » data, whence to deduce the composition of the three 



specimens. 



No. 1. 



No. 2 



No 3. 



a. 



Loss of carbonic acid by digestion in di- 













12.0 



14.6 



7.0 



h. 



Loss of water (and some carb. acid ?) by- 











heating without air in glass tube, 



5.0 



7-0 



3.0 



c. 



Total loss on calcination with access of air, 



17.5 



17.8 



21.0 



c2 



Ditto average of two other trials (more 













20.0 



20.3 



23.5 



d. 



Oxide of copper taken up from calx c 













37.7 



49.2 



73.7 



*. 



Residue of insoluble earths and ox. iron, 













44.8 



33.0 



5.3* 



/ 



Residue from digestion of crude ore in 











20.0 



13.9 



19.0 



£• 



The same, after burning off the sulphur 











and redigesting in do 



20.0 ? 



8.5 



0.0 



L 



Sulphur, separated on boiling in strong 













0.6 



2.1 



9.0 



i. 



Sulphate of barytes precipitated after- 













1.4 



17.3 



28.5 



h 



Weight of metallic copper actually reco- 











vprpd from c 2 



28.5 



52:2 



59.0 



u In regard to d, No. 3, it was observed on 



digestion in cold 



nitric 



acid, that a very considerable portion of the calx of copper was of a 

 red color, or in the state of protoxide, or perhaps in a metallic state ? 

 and was not taken up without disengagement of nitrous gas;—the 

 weight 73.7 must therefore be increased, to give the true weight in 

 terms of the peroxide. This is also proved by the amount of loss in 

 e, 21.0, which is considerably in excess; and it was remarked on 

 removing the calx from the fire that it was agglutinated, so as per- 

 haps to have prevented the access of air to oxidate the interior. — The 

 sulphur enables us to approximate the correction of this item; for 12.8 

 requires 51.5 copper,=64.3 black or peroxide; and this, added to 22.8, 

 the peroxide of the carbonate, would give 87.7; which is 14.0 greater 

 than the actual return from the fire. — Again, deducting the deficiency 

 after calcination (c) 21.0,from the sum of the three volatile ingredients — 

 sulphur, 12.8; carbonic acid, 7.0; and water 3.0=22.8, there remains 

 but 1.8 for the weight of oxygen absorbed in place of the sulphur; 

 whereas 12.8 are required.— Adding the difference 11.0 to d, we shall 

 have 84.7. This number will be found to be a little in defect from the 

 subsequent results ; while 87-7 is a little too great ; a mean may there- 

 fore be adopted. 



* This residue may have consisted partly of sulphuret of copper that had escaped de~ 

 eomposition in the fire ; for another specimen waa wholly soluble, and little iron wa* 

 present in the solution. 



