2.66 An Analyfis of two Mineral Springs, &c* 



now let a piece of bright iron be put into the liquor ; in this 

 cafe, copper is depofited on the furface of the iron in a me- 

 tallic ftate. 7. Put a fmall piece of fulphat of argill into a 

 glafs of the folution, after frefli iron filings have been di- 

 gefted in it j a white ftratum forms at the bottom of the 

 glafs, but after fome time it is re-diffolved, and the liquor 

 refumes its tranfparency. 8. Put a little oxygenated muriat 

 of mercury into a glafs of the hepatifed folution ; as it dif- 

 folves, a white matter collects on the fides, and falls to the 

 bottom of the glafs. 9. Infufion of galls, after the frefh iron 

 has been digefted with the folution, precipitates the iron of 

 a dark colour ; ftill the prufliat of potalh does not become 

 turbid. From all thefe facts it is clear, that as the iron com- 

 bines with the fulphur of the hepjtic gas, a peculiar fubftance 

 is formed and diflblved in the water, which has hitherto been 

 unnoticed by chemical writers, as far as has fallen within my 

 information. That this fubftance is contained in the waters 

 of the fpring under our prefent examination, feems fully 

 eftablifhed by the concurrent evidence of fa many pheno- 

 mena in which they completely coincide. Compare m, 

 I & 2. IV. 1, 2, 3, 4, & 5. 



IX. MANGANESE EXPOSED TO HEPATIC GAS. 



To complete the demonftration, it is necefjary to examine 

 the action of hepatis gas upon manganefe. 



I. I digefted fome black oxyde of manganefe in hepatifed 

 water: it had been pievioufly purified, by being boiled re- 

 peatedly in diftilled water*. The hepatic fmell of the gas 

 is quickly impaired; and in 24 hours, if enough of the oxyde 

 has been ufed, it is perfectly deftroyed ; ftill the liquor has a 

 peculiar fmell, which can hardly be called offenfive : no gas 

 is extricated in this procefs. The liquor, after nitration, was 



* The readied method of purifying this fubftance is to boil it ftrft in a 

 very l^r^u quantity of rain water; after which, aftngle boiling in diftilled 

 water will be fufficicnt to extract every Jolublc impurity. 



4 examined 



