108 Hints on the Subject of Jnmal Secretions* 



If we suppose the water and the earthy residue to be only 

 accidentally present, then the only essential constituents are 

 the first four, and the ore would be a compound of 



Iron - 31-0 



Copper - 19'2 



Arstnic - 15*7 



Sulphur - 14-1 



100-0 



If wc compare this analysis with several analyses of gray 

 copper ore, lately published by Klaproth, we shall hnti, 

 that the constituents are the same in both ; but the pro- 

 portions of the two first ingredients are very nearly re- 

 versed. Klaproth obtained from 0*4 to 0-5 of copper, and 

 from 0*22 to 0*27 of iron. This renders it obvious, that 

 the two ores were not in the same state. I have littk doubt, 

 that the difference, however, is merely apparent, and that 

 it arose, altogether, from a quantity of iron pyrites, and 

 perhaps also of arsenic pyrites, which I could not separate 

 from the gray copper ore which I examined. Both of these 

 minerals could be distinctly seen in many of the specimens, 

 intimately mixed with the gray copper; and I have no 

 doubt that the same mixture existed, even in those speci- 

 mens which were selected as purest. The diflference in the 

 proportions of copper and arsenic, obtained by Klaproth* 

 m his various analyses, is so considerable, as to lead to a 

 suspicion, that even his specimens, in all probability, con- 

 tained a mixture of foreign matter. 



XVIII. Hints on the Subject of Animal Secretions, By 

 EvERARD Home, Esq,^ F.R,S*f Communicated by ike 

 Society for the Improvement (f Animal Chemistry J. 



JL HE brilliant discoveries of Mr. Davy on the powers of 

 electricity in producing chemical changes, suggested to me 



the 



TGehlen's Journ. vol. v. p. 9, li, 13. 

 From Philosophical Transactions, for 1809, Part II. 

 \ Dr. WoUaston's observations inserted in the Philosophical Magazine, 

 •were published after this pa]>er had been laid before the Society. 



1 was led to the present investigation, while preparing my lectures on the 

 Kunterian Museum, in which the secretion* in different animals are ta be 

 considered. In September last, I engaeed Mr. \Villiam Brande to assist me 

 in prosecuting the inquiry. In Noveniber, I communicated my opinions to 

 Sir Joseph Banks, aud stated that I should bring them forward in my leC' 

 . , , turesj 



