WAT

WAT

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We fhall add in the appendix a table of afew of the moll important correfponding quan-tities of precipitates with falts which are themolt frequently ufed in analyfis.

To proceed with the examination of the de-aerated water freed from the earthy carbonats.

Evaporate a given quantity (which with moftwaters fhould not be lefs than about a gallon)with a heat which, to fave time, may be that ofboiling till towards the end, when a more gentleheat muft be ufed to avoid decompofing orvolatilizing any part of the ingredients. Theevaporation may be carried on in almoft anyclean veffel, efpecially where no excefs of acidexifts in the water, but when only a few ouncesare left, it fhould be transferred to a glafs orfilver difh, with every tiling that may havefubfided in the boiling, and brought by a flowfire to perfect drynefs. The further manage-ment of this refidue depends on the nature ofits contents. If previous experiments havefliewn that no earthy or metallic fait exifts inthe boiled water, it will be fufficient to re-dif-folve it in a little warm diftiiled water, bywhich any filex that may be contained will beleft behind ; and the latter may be ftilt furtherknown by its infolubility in muriatic acid, andby fufion with foda.

The aqueous folution can then contain onlyany acid or alkali which may exilt in excefs,and any neutral falts with alkaline bafes. Thenfaturate an aliquot part of the folution and aflayit with tartareous acid, which in this concen-trated flare, will precipitate cream of tartar ifpotafh exifts. If none is found (which is byfar the moft common) the alkali muft then befoda, and the nature of the acids being alfofound, the refpebtive quantities of the neutralfalts may eafily be inferred in the way abovementioned. Thus if the water indicate fulphu-ric and muriatic acid, and an excefs of foda(which is the cafe with the Carlsbad water,analyfed by Klaproth ) the alkali is firft to be fatu-rated with fulphuric acid of a known ftrength,and the whole fulphat decompofed by acetiteof barytes. Then, calculate the equivalent quan-tity of fulphat of foda to the fulphat of barytesobtained, fubtrabl that portion of it which isformed by the fulphuric acid employed to iatu-rate the uncombined foda, the reiidue is theportion of fulphat of foda natural to the water,'lire muriat of foda is then indicated by nitratof filver, allowing ico parts of luna cornea tobe equivalent to 428.25 parts of common fait.

The excels of fixed acid where it exifts isalmoft always the fulphuric, but it has hitherto

been only found in company with alum, orother fulphuric falts, that have a natural excefsof acid. If it fhould ever be found onlyaffociated with alkaline fulphats or muriats,this excefs may be found by adding baryticwater merely to faturation, and no further,which will then only indicate the excefs of acid.

But the greater number of mineral waterscontain fome earthy fait, the acid of which isfixed, fo that it remains in folution after boilingand concentration. This acid is hardly everany other than the fulphuric and muriatic, andthe earth is moft commonly lime or magnefia.Therefore only four earthy falts may be ex peeled(not all together indeed, as they wou d decom-pofe each other) namely, fulphat of lime, muriatof lime, fulphat of magnefia, and muriat of mag-nefia. Of thefe falts the fulphats are infolublein alcohol, but the muriats are extremely foluble.This therefore affords a very ufeful means offeparating fome of them. For this purpofe putthe entire dry refidue in a phial, pour on it aboutfive or fix parts of highly rectified alcohol, andJet the mixture remain for fome hours withfrequent agitation. The alcoholic folution canthen contain only muriat of lime and magnefia,if the alcohol has been highly re£tified ; if notit may alfo diffolve a little muriat of foda. Themethod of feparating and eilimating a mixedmuriat of lime and magnefia, has already beenmentioned. The refidue which is not difl’olvedby the alcohol may contain the fulphats of limeand maanefia, of which the latter fait is eafilyfoluble in water, but the former with great diffi-culty uolefs affifted by an acid. The mode offeparating thefe has alfo been mentioned.

With regard to fulphat of lime which is focommon an ingredient in waters, it is of ufe toknow that when it is in folution in as fmall ahulk of water as poffible, and efpecially whenaffifted by an excels of acid, it may be totallyprecipitated by adding a much fmaller quantityof alcohol than will feparate any other of thefulphats, as has been mentioned under thearticle Sulphat of Lime.

Sulphat of iron is now and then found inmineral waters, though much more rarely thanmight he expedited from the frequency cf pyritesin moft parts of the earth. When a water re-mains chalybeate after boiling, we may prettylately infer that the iron is united to the-ful-phuric acid But as fulphat of iron is partlydecompofed by -expofare to air, the refidue,after the water has been evaporated to drynefs,contains both fulphat of iron and fome uncom-bined oxyd of this metal, and the fulphat is then

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