1822.] Variegated Copper Ore. 87 



In 120 parts. In 100 parts. 



Sulphur 28-5 23-75 



Iron 16-8 14-00 



Copper 73'28 61-07 



Silica 0-6 0-5 



119-18 99-32 



Loss 0-82 0-68 



120-00 100-00 



What has been already stated as to the composition of the 

 sulphuret of iron and that of copper, will show that 16-8 of iron 

 require 9*6 of sulphur to form the protosulphuret or magnetic 

 pyrites, leaving 189 of sulphur to unite with 73-28 of copper, 

 jfow as copper combines with one-fourth of its weight of sul- 

 phur, 73*28 will require 18-32, leaving an excess of 0*58 of 

 sulphur. 



From what has been now detailed, I think it will appear that 

 the variegated copper is a definite compound of one atom of 

 sulphuret of iron and two atoms of sulphuret of copper, or indi- 

 cated, as already noticed, by one of the analyses of Chenevix, or 

 it may be regarded as consisting of magnetic pyrites and vitreous 

 copper ore. On this view of the subject, its atomic constitu- 

 tion will be as follows : 



1 atom of sulphuret of iron 16 + 28 = 44 



2 atoms of sulphuret of copper 16 -f 64 x 2 = 160 



204 

 Or it consists of 



Sulphur 28-23 23-53 



Iron 16 47 13-73 



Copper 75-3 62-74 



120-00 100-00 



These quantities, it will be observ^ed, do not differ from the 

 analysis which I have given, more than may be reasonably 

 allowed for the errors of operation. 



Article II. 



Meteorological Observations made at Crumpsally in Lancashire., 

 By Mr. John Blaekwall. 



(To the Editor of the Annals of Philosophi/.) 



SIR, CrumpsaUy Dec. 17, 1821. 



I LATELY proposed a plan for taking daily observations of the 

 temperature of the atmosphere {Annals of Philosophy, vol. ii. p- 



