VOL. LXVI.] PHILOSOPHICAL TRANSACTIONS. QQ 



of these substances. But, pressing a finger in the gentlest manner on the 

 amber, after heating, will excite it. Indeed, a fine piece, which Mr. H. fre- 

 quently carried in his pocket, he always perceived to be electrical, without any 

 other friction than what it received from the pocket. And negative electrics, 

 per se, being once thoroughly excited, are observed to retain their electrical 

 quality very long, as they do not so soon attract the moisture in the atmosphere 

 as glass. Glass however will retain its electricity many hours. Mr. Canton in- 

 formed him, that having excited a rod of glass very strongly, he set it at some 

 distance from the fire in his parlour, and found that it was electrical, after stand- 

 ing in that situation, in dry air, 24 hours. How much longer it would have 

 retained its electricity, had he let it remain there, he knew not. How long a 

 large and neatly prepared Leyden bottle will retain its charge, so as to be sen- 

 sibly electrical, Mr. H. had never experienced ; but Dr. Priestley observes. 

 History of Electricity, p. 5)6, that he has more than once received such 

 shocks, as he should not like to receive again from the residuum of his battery, 

 even "2 days after the discharge, and when papers, books, his hat, and many 

 other things, had lain on the wires the greatest part of the time. Even the 

 residuum of a residuum, he says, he has known to remain in his battery many 

 days. One thing, however, is very remarkable in Mr. Adams's apparatus, viz. 

 supposing the negative electric to have parted with its electricity to the rubber ; 

 why, when the coated board or plate of metal is set upon it, and that plate is 

 touched by a finger, the equilibrium is not thus presently restored .-' But, 

 perhaps, when the electric matter, naturally inherent in bodies, is once 

 thoroughly excited and put in action, it is not so soon as might be suspected 

 reduced again to a quiescent state, especially in bodies so peculiarly adapted to 

 affect each other as these appear to be, 



XXXIII. j4ccount of the Iron Ore lately found in Siberia. By Petr. Simon 

 Pallas, M.D., F.R.S. Dated Petersburgh, Nov. 6, 1775. p. 523. 



" I have embraced the opportunity (says Dr. P.) of a parcel I sent to Mr. 

 Drury, to offer the Society a specimen of the native iron, of which I found out 

 a large mass in the Siberian mountains, which is now transporting to Petersburg. 

 I read in some foreign journals, that a short account of this mass has been pub- 

 lished in the last volume of Philos. Trans, from a letter of M. Staehlin, of our 

 Academy ; but as the contents of it, drawn from the informations 1 gave to our 

 Academy in my itinerary relations, seem not to have been exact, I beg leave to 

 give you here a faithful and fuller account of the place and circumstances in 

 which that memorable mass was found. 



It is to be observed, that in the neighbourhood of the river Jenisei, one of 

 the largest that runs from the south through Siberia and to the Northern 



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