47 



decompose this ore, he had recourse to a process to which he was 

 led by some instances he had before observed, in which a mixture of 

 two compounds of the same ingredients, but in different proportions, 

 remained insoluble, while a third substance seemed to operate upon 

 at least one of these two compounds, and to produce the decompo- 

 sition that was aimed at. The following is the manner in which he 

 explains this operation : When a metallic oxide A, for instance, 

 containing 25 per cent, of oxygen, is in contact with the metallic 

 oxide B, containing 10 per cent., they will each remain quiescent in 

 their respective states : but if a solvent C, for which the substance B 

 has no affinity at 10 per cent, of oxygen, but a powerful one at 15 

 or 20 per cent., comes to be added, then may the oxide A lend a 

 part of its oxygen to B, in order to enable it to combine with the 

 solvent C. Thus w"hen phosphoric acid had dissolved all it could of 

 the pulverized ore, its oxygen in the part undissolved was concen- 

 trated, as it were, to the amount of about 20 per cent. ; and all that 

 which could not be dissolved, would, through a twofold affinity of 

 copper for oxygen to the amount of 20 per cent., and of phosphoric 

 acid for the oxide of copper of that degree of oxidation, yield up its 

 entire share of oxygen, to favour the combinations which took place 

 in the new order, the only one which could exist among the sub- 

 stances now present. 



From the variety of experiments founded upon this reasoning, it 

 has been gathered, that the copper in this ore contains much less 

 oxygen than has ever been suspected in any oxide of copper ; and 

 that, from the quantity of the copper which was precipitated in the 

 metallic state by iron, it appears to be combined in the proportion 

 of only 11^ per cent., the rest being pure copper, a state of metal- 

 lic concentration of which no instance has as yet been observed in 

 nature. 



It is lastly suggested, that, considering not only the great purity 

 of this ore, but also the singular facility with which this useful metal 

 may be extracted from it, it will be found much superior to every 

 copper ore hitherto discovered. It contains no iron and no sulphur ; 

 the absence of which latter is a peculiar advantage. It is hence 

 strongly recommended to the proprietors of mines to be particularly 

 attentive to this ore, which is said not to be uncommon in some parts 

 of Cornwall, whereby they are likely not only to further their private 

 advantage, but may also materially contribute to promote the public 

 utility. 



A Historical and Anatomical Description of a doubtful amphibious 

 Animal of Germany, called, by Laurenti, Proteus Anguinus. By 

 Charles Schreibers, M.D. of Vienna. Communicated by the Right 

 Hon. Sir Joseph Banks, Bart. K.B. P.R.S. Read March 26, 1801. 

 [Phil. Trans. 1801,^. 241.] 



This singular production has hitherto been found only in a small 

 lake in Carniola, called Sitticher See, and has never yet been met 



