194 SPRINGS, RIVEKS, CANALS, LAKES, 



pouring a few drops of the brown and fuming acid on distilled wa. 

 ter, in which the gas disengaged from caustic alkaline sulphure, 

 heated in a retort, has been received. This artificial hepatic wa- 

 ter, which does not considerably differ from natural sulphureous 

 waters, except in the circumstance of its being more difficult to 

 filter, and its always appearing somewhat turbid, affords a precipi- 

 tate in a few seconds, by the addition of nitrous acid ; the precipi- 

 tate is of a yellowish white; when collected on a filter and dried, 

 it burns with the flame and smell of sulphur, and in other respects 

 has every character of that inflammable body. Nitrous arid seems 

 to alter sulphurated hydrogen gas in tiie same manner as it does all 

 other inflammable substances, by virtue of the great quantity of 

 oxygen it contains. Scheele has recommended the oxygenated 

 muriatic acid to precipitate the sulphur from waters of this nature : 

 only a very small quantity of it must be used, otherwise the sulphur 

 will be burned and reduced to the state or' sulphuric acid. Sulphu- 

 reous acid precipitates the sulphur very readily tiom waters which 

 contain it. 



There are few re-agents whose mode of action is less known than 

 that of the alkaline lixivium of blood, which has been called 

 phlogisticated alkali / it has been long since ascertained, that this 

 liquor contains Prussian blue, or prussiat of iron, ready formed , 

 it has been thought that this blue might be separated by the addi- 

 tion of an acid ; and in this state it has been proposed as a sub^ 

 stance capable of exhibiting iron existing in mineral waters. Nothing 

 can be more uncertain than the complete separation of prussiat of iron 

 from this prussiat of potash made with blood. This lixivium ought 

 therefore to be no longer used as a re-agent. Macqucr having discov- 

 $red that Prussian blue is decomposed by alkalis, proposed potash 

 saturated with the colouring matter of this blue, as a test to ascertain 

 the presence of iron in mineral waters. But as the liquor itself likewise 

 Contains asmall quantity of Prussian blue,which may be separated by 

 means of an acid, as Macquer has shown, Baume advises that two or 

 three ounces of distilled vinegar be added to each pound of thisPrus* 

 sian alkali, and digested in a gentle heat, till the whole of the Prussian 

 blue is precipitated ; after which pure fixed alkali is to be added to 

 saturate the acid of vinegar. Notwithstanding this ingenious pro- 

 cess, Fourcroy has observed, that the Prussian alkali, purified by 

 "vinegar, deposits Prussiau blue in process of time,, more especially 



