434 ^^f^'- Waters. — $rt of IreA. 



that thofe who have hitherto confidered thefe waters as inefficacious, will agree with 

 The, I imagine, in allowing that thefe principles muft have confiderable medical 

 properties. 



It feems difficult to account for the azotic gas which rifes with thefe waters. The 

 eountry round Bath contains prodigious quantities of lime-ftone, in the greateft part of 

 which I have been able to deteft the exuviae of fea animals. As there mull have been 

 a great depofition of animal fuhftances, and as thefe waters apply a continued and pow- 

 erful heat to the lower ftrata of lime-ftone, the azotic gas may thereby be detached, and 

 brought to the furfece with them. It may affo happen that the atmofpheric ak may find 

 a palTage into the bowels of the earth, fo that affifted by the great heat of thefe waters 

 the oxygene may be combined with fiAftances for which it has a great attrafiion, allow- 

 ing the azotic gas to pafs and appear by itfelf at the furface. Hence may arife the car- 

 bonic acid, which may be detached from the lime-ftone by the acids formed by the 

 combinations with the oxygene, producing thereby the falphate of lime, &c. fo eafily 

 iifcovered in the Bath waters. 



VIL 



Anahjis of an Ore of Iran, the Cempofition of which has been hitherto mifunderjlood, iTy 

 Mr, William HinRY; including a Letter on Ores of Iron, addrejfed ta Mr. 

 Thomas liENRY, F.R-S. ^;j CttARLii& Hatchett, Esq. T.R.S. 



Manchefcr, Dec. 20, »799. 



A, 



lBOUT two years ago*, adryfalterof this town requefted me to examine chemically^ 

 a fubftance, of which he had purchafed a large quantity, prefuming-it to be plumbago. 

 Mere infpeftion, however, of its external charafters, induced me to fiipp»fe that he had. 

 been deceived ; and, after a careful analyfis, my fufpicion proved to be well-founded. 

 X fend you the following account of the mineral, and its compofition ;. becaufe it appears- 

 to have been, hitherto, not fufficiently underftood, and even to have been miftated, 

 by that excellent mineralogift, Mr. Kirwan. 



The refemblance of this nuneral to powdered plumbago is^ ftriking enough to miflead 

 a hafty obferver. It is in the ftate ofa fine fcaley powder, of afleel-grey colour.with fome- 

 what of a reddifh hue, which appears more evidently when it is- finely fpread on a white 

 ground. Its luftre is metallic, and it poflcfles no tranfparency. When rubbed between 

 Ihtfingers, k lias an unftuous feel ;, and adheres, but does not give a permanent ftain to 



