WATER. 



lution of lead. Carburetkd hydrogen may be detefted by 

 its inflammable nature, and by its yielding carbonic acid by 

 corabuftion. Phofphuretted hydrogen may be known by its 

 peculiar fmell and fpontaneous inflammability. 



3. Atmofpheric Air : Oxygen and Azote — The prefence 

 of oxygen gas may be known by its power of fupporting 

 combuftion, and by the diminution which takes place on 

 mixing it with nitrous gas or phofphorus. There is no 

 teft for azote, but it is fufiiciently charafterized by its ne- 

 gative properties. 



4. Alkalies and Alkaline Earths. — The alkalies and alkaline 

 earths, as well as their carbonates, are diftinguiflied in general 

 by the following tefl;s. Turmeric paper is rendered brown 

 by alkalies, or reddifti-brown, if the quantity be minute. 

 Brazil wood is rendered blue not only by the alkalies, but alfo 

 by the alkaline and earthy carbonates. Litmus paper reddened 

 by vinegar is reftored to its original colour by alkalies, and 

 alfo by the alkaline and earthy carbonates. If thefe changes 

 are fugacious, we may conclude that the alkali is ammonia. 

 /Vxf^ alkalies are indicated when a precipitate is produced by 

 muriate of magnefia after being boiled. The volatile alkali^ 

 or ammonia, may be readily diftinguiflied by its fenfible 

 properties. The earthy and metallic carbonates are precipi- 

 tated by boiling the water containing them, except carbo- 

 nate of magnefia, which is only precipitated imperfeftly. 

 With refpedl to the individual fubftances of this clafs — 

 Potafh may be dift;inguifhed by the precipitate it produces 

 with the muriate of platina, the fulphate of alumina, and 

 tartaric acid. For foda there is no good teft, but its falts are 

 eafily diftinguiflied from thofe of potafli. Ammonia may be 

 knowrt from its odour and other properties above-mentioned. 

 Z.ime is detefted by means of the oxalic acid, which occa- 

 fions a white precipitate. To render its operation certain, 

 however, the mineral acids, if prefent, muft be faturated with 

 an alkah. Magnefia and alumina. Pure ammonia precipi- 

 tates both thefe earths and no other, provided the carbonic 

 acid has been previoufly feparated. Lime-water alfo pre- 

 cipitates only thefe two earths, provided the carbonic and 

 fulphuric acids be previoufly removed. The alumina may 

 be feparated from the magnefia by boiling the precipitate in 

 pure potafli, which diflblves the alumina and leaves the mag- 

 nefia. Silica may be afcertained by evaporating a portion of 

 the water to drynefs, and rediflblving the precipitate in 

 muriatic acid. "Thejilica remains behind undiflblved. 



5. Metals. — The prefence of metals may be fufpedled, if 

 precipitates are produced by the prufliate of potafli and ful- 

 phuretted hydrogen. Iron may be difcovered by the follow- 

 ing lefts. The addition of tinfture of nut-galls gives water 

 containing iron a purple or black colour. If the tinfture 

 has no effeft upon the water after boiling, though it co- 

 loured it before, the iron is in a ftate of carbonate. Pruf- 

 fiate of potafli produces a fine blue precipitate in water 

 containing iron, provided no excefs of alkali be prefent, 

 which muft be faturated with an acid. Manganefe is occa- 

 lionally prefent in minute quantity, efpecially in chalybeate 

 waters. It may be precipitated by ammonia with proper 

 p»ecaution, and is known by the beautiful violet hue it im- 

 parts to borax, on being fufed with that fubftance. Copper 

 is occafionally met with in waters. It may be detefted by 

 the fine blue colour produced on the addition of ammonia ; 

 by the red-coloured precipitate produced by the prufliate 

 of potafli ; or it may be obtained in the metallic ftate by 

 plunging into the water a piece of poliflied iron. Lead 

 is fometimes found in waters that have traverfed leaden 

 pipes. Such waters are blackened by a cur/ent of fulphu- 

 retted hydrogen gas ; but to render the prefence of the metal 



more certam, a portion of the water is to be evaporated to 

 drynefs ; the remainder is to be tefted with nitric acid, and 

 afterwards tefted with folutions of the carbonate and ful- 

 phate of potafli, which produce white precipitates, from 

 which the lead may be readily obtained in the metallic 

 ftate. 



6. Acids — Carbonic acid, in a free or uncombined ftate, 

 may be detefted by lime-water, which occafions a precipi- 

 tate foluble with eff'eivefcence in muriatic acid ; or by the 

 infufion of litmus, which is reddened, but becomes again 

 blue on expofure to the air. Water containing free car- 

 bonic acid lofes this property of reddening htmus by boil- 

 ing. The fulphuric acid is readily diftinguiflied by the 

 muriate, nitrate, or acetate of barytes, ftrontian, and lime, 

 and alfo by the nitrate or acetate of lead. The moft deh- 

 cate of thefe tefts is the muriate of barytes : this pro- 

 duces a white precipitate, infoluble in muriatic acid. 

 To enfure the operation of this teft, it is neceflary 

 that no earthy or alkaline combination be prefent in the 

 water. The muriatic acid is detefted by the nitrate of 

 filver, which occafions a white curdy precipitate, info- 

 luble in nitric acid. To enfure the operation of this 

 teft, the alkaline and earthy carbonates muft be previoufly 

 faturated with nitric acid ; and the fulphuric acid, if any be 

 prefent, muft be feparated by the nitrate of barytes. Bo- 

 racic acid is detefted by means of the acetate of lead. The 

 precipitate formed is infoluble in acetic acid. To render 

 this teft certain, the alkalies and earths muft previoufly be 

 faturated with acetic acid, and the fulphuric and muriatic 

 acids removed by means of the acetate of ftrontian and the 

 acetate of Clver. 



Such is a brief account of the diff'erent tejls ufually em- 

 ployed to deteft the ingredients prefent in mineral waters, 

 and the moft obvious precautions to be obferved in their ufe. 

 It is proper, however, to obferve, that there are many cir- 

 cumftances to be attended to, in the ufe of tefts in general, 

 which can only be learnt by perfonal obfervation and prac- 

 tice, and that the inexperienced chemift is very liable to be 

 niifled by them. 



d. Having thus acquired, by the employment of tefts, 

 a general knowledge of the ingredients contained in a mineral 

 water, the next objeft is to endeavour to afcertain the 

 quantities and modes of combination in which they exift ; 

 and this conftitutes by far the moft difUcult part of the 

 inquiry. 



There are two general modes of condufting the analyfis 

 of a mineral water : one is to feparate, by various appro- 

 priate manipulations, the different ingredients in the fame 

 compound forms in which they are fuppofed to aftuaUy exift. 

 in the water. The other, recommended particularly by 

 Dr. Murray, is to afcertain, chiefly by means of tefts, the 

 quantities of the different fimple fubftances, and afterwards 

 to ejlimate from them the quantities of the compounds. 

 The firtt of thefe modes, and in fonie inftances a combina- 

 tion of both, is the one which has hitherto been generally 

 adopted by chemifts ; we ftiall, therefore, give a fliort ac- 

 count of the manipulations had recourfe to for feparating 

 a few of the fubftances moft ufually occurring in mineral 

 waters. 



I. The gafeous matters are firft to be feparated in the 

 manner formerly mentioned, and their grofs amount afcer- 

 tained by admeafurement in a jar graduated into cubic 

 inches. Sulphuretted hydrogen, if it be prefent with other 

 gafes, is firft to be feparated by immerfing the jar in warm 

 water, and introducing nitric acid, which abforbs the ful- 

 phuretted hydrogen, and the diminntion of bulk denotes its 



quantity. 



