464. Jin Analyfts of two Mineral Springs 



acid. I. Idigeftei iron filings, previoufly purified by r«r 

 peated wafhings with diftilled water, in a folution of hepatic 

 gas in diftilled warer : the bo tie was filled with the folution, 

 and corked. The iron was prefently a£ted upon ; numerous 

 bubbles arofe, which drove the cork out of the bo:tle ; they 

 were ftrongly inflammable, and probably, therefore, pure 

 hydrogen gas: the liquor gradually loft its hepatic odour; 

 and at the end of fome days it had a fmell a good deal re- 

 fembling that of ftagnant rain water ; as the bubbles ceafed 

 to be produced it recovered its tranfparency. The liquor 

 was then examined by re-agents. Infufion of galls ftruck a 

 yellow tinge ; pruffiat of potafh gave a little whitifh cloud ; 

 nitrate of filver and muriat of barytes, each very minute pre- 

 cipitates ; pure potafh a yellow precipitate, but not till the 

 liquor had flood an hour or two. The liquor does not de- 

 pofit any thing, either by expofure to the atmofphere or by 

 a boiling heat : but by this laft procefs fomething, perhaps 

 a little gas which has efcaped the acYion of the iron, flies 

 off; fince the precipitate with nitrat of filver was white af- 

 ter the boiling, which had previous to it been black. Very 

 little can be deduced with certainty from thefe trials, except 

 the prefence of a little fulphuric acid. It feemed of confe- 

 quence to determine whether this is generated in the pro- 

 cefs, or is accidental from the fulphuric acid which was 

 ufed to extricate the gas. 



2. To determine this point I repeated the experiment, 

 ufing the muriatic acid to generate the gas, inftead of the 

 fulphuric. In this cafe, the liquor, as Bergman has faid, is 

 not at all rendered turbid by pruffiat of potafh ; neither does 

 the muriat of barytes precipitate any thing : the precipitate 

 by pure potafh is now white, but as minute as before : ni- 

 trat of filver makes a ye'low cloud both before and after 

 boiling : infufion of galls ftrikes a yellow tinge. Hence it 

 is clear, that hepatic gas, when produced by fulphuric acid, 

 carries with it a little of the acid which cannot be feparated 

 by paffing it through water. It feems probable alfo, that a 



little 



