Encyclopaedia Perthensis; Or Universal Dictionary of the Arts, Sciences ...

folvent to many of the earths and even metallic bodies, had thwarted all the attempts of former chemifts to detect the compofition of thefe liquids. Since the discovery of this acid, the analysis of mineral waters has advanced with great rapidity, in confequence, chiefly, of the admirable differtation on the fubject published by BERGMAN in 1778. Since that period, much has been done by Gioanetti, Back, Klaproth, Weftrum, Fouroroy, Brezé, Kirwan, and many other eminent chemists: fo that, notwithstanding the difficulty of the fubject, scarcely any branch of chemiftry has made greater progrefs, or is farther advanced, than the knowledge of mineral waters."

(9.) MINERAL WATERS, CAUSES OF THE HEAT OF. See SPRING, N° 9; and Burning, No 25. (10.) MINERAL WATERS, DIVISIONS OF. "In the greatest part of mineral waters (fays Dr Thom fon) there is ufually some substance present (see 14. 15.), which, from its greater proportion or activity, ftamps the character of the water, and gives it thofe properties by which it is moft readily diftinguished. This fubftance claims the greateft attention, while the other bodies, which enter in a fmaller proportion, may vary, or even be abfent, without producing any fenfible change. This circumftance enables us to divide mineral waters into claffes, diftinguished by the peculiar fubftance which predominates in each. Accordingly, they have been divided into 4 claffes: namely, r. Acidulous; 2. Chalybeate; 3. Hepatic; 4. Saline."

I MINERAL WATERS, ACIDULOUS,"contain a confiderable proportion of carbonic acid. They are easily distinguished by their acid tafte, and by their sparkling like Champaign wine, when poured into a glafs. They contain almoft conftantly fome common falt, and in general alfo a greater or smaller proportion of earthy carbonats."

II. MINERAL WATERS, CHALYBEATE, "contain a portion of iron,and are easily distinguished by their property of ftriking a black with the tincture of nut-galls. The iron is ufually held in folution by carbonic acid. It very often happens that this acid is in excefs; in which cafe, the waters are not only chalybeate, but acidulous. This is the cafe with the waters of Spa and Pyrmont. In fome inftances the iron is in the ftate of a fulphat. The waters holding the fulphat of iron cannot well be applied to medicinal uses: they may be readily diftinguifhed by their property of contiBuing to ftrike a black with tincture of nut-galls, even after being boiled or filtered; whereas boiling decompofes the carbonat of iron, and caufes its bafe to precipitate."

III. MINERAL WATERS, HEPATIC. "The hepatic or fulphureous waters are thofe which contain fulphurated hydrogen gas. These are easily diftinguished by the odour of that gas, which they exhale, and by their property of blackening filver and tead. The nature of thefe waters long puzzled chemifts. Though they often depofit fulphur fpontaneously, yet no fulphur could be artificially separated from them. The fecret was at laft difcovered by Bergman. Thefe waters are of two kinds: in the firft, the fulphurated hydrogen is uncombined; in the 2d, it is united to lime or an alkali. They are frequently alfo impregnated

with carbonic acid, and usually contain fome mu-
riats or fulphats."
IV. MINERAL WATERS, SALINE,
contain
only falts in folution, without iron or carbonic
acid in excefs. They may be distinguished into
4 different orders: Thofe of the 1ft order contain
falts whofe bafe is lime, and generally either the
carbonat or fulphat. They are named hard wa-
ters, and have but a flight difagreeable tafte. The
2d are thofe in which common falt predominates."
They are readily recognized by their falt tafte,
and ufually contain fome magnefian and calca.
reous falts. Waters of the 3d order contain ful-
phat of magnefia. They have a bitter tafte, and
are purgative. Those of the 4th order are alka-
line, containing carbonat of foda. They are easily
diftinguished by their property of tinging vege-
table blues green.”

(11.) MINERAL WATERS, GENERAL RULES FOR EXAMINING. When a mineral water is to be examined, the following rules fhould be obferved: 1. Experiments ought to be made near the fpring, if poffible. 2. The fituation of the spring, the nature of the foil, and the neighbouring rifing grounds, ought to be examined. 3. Its fenfible qualities, as its fmell, tafte, colour, are to be obferved. 4. Its fpecific gravity and heat are to be afcertained by the hydrostatical balance and the thermometer. For greater certainty, let the neck of a wet bladder be tied to the neck of a bottle containing fomé of this water. By fhaking the water, any gas that it contains will be difengaged, and will fwell the bladder. If the neck of the bladder be then tied with a string above the bottle, and be cut below this ftring, fo as to feparate the bladder from the bottle, the quantity and nature of the contained gas may be further examined. 5. Obferve the changes fpontaneously produced upon the water in elofe and in open veffels, and with different degrees of heat. If by thefe means matter be cryftallized or depofited, it must be set apart for further examination. These experiments will almoft certainly indicate the nature of the water. We must then proceed to the decompofition of it, either merely by evaporation and diftillation, or with the addition of other fubftances, by which the matters contained in the water may be precipitated.

(12.) MINERAL WATERS, METHODS OF DIScOVERING VARIOUS SUBSTANCES IN. The following are the principal means by which the yarious substances contained in mineral waters may be difcovered and proved, without decompofing the water by evaporation or by diftillation. If any portion of difengaged acid or alkali be contained in water, it may be known by the tafte, by changing the colour of violets or of turnfol, and by adding the precife quantity of acid or of alkali that is neceffary for the faturation of the contained difengaged faline matter. Sulphur, and liver of fulphur, may be difcovered in waters by their fingular fmell, and by the black colour which thefe fubftances give to white metals or to their precipitates, but efpecially to filver. Vitriolic falts with earthy bafes may be difcovered, 1. By adding fome fixed alkali, which decompofes all these falts, and precipitates their earthy bafis; and, 2. By

adding a folution of mercury in nitrous acid, which alfo decompofes thefe falts, and forms a turbith mineral with their acid. But for this purpofe the folution ought to have a fuperabundant quantity of acid; for when perfectly faturated, it forms a precipitate with any water; and indeed, all metallic folutions in acids are capable of decompofition by water alone, and fo much more eafily as the acid is more perfectly saturated with the metal. Martial vitriol, or iron combined with any acid, or even with gas, fhows itself in waters by blackening an infufion of galls, or by form ing a Pruffian blue with the phlogifticated alkaline lixivium. The vitriol of copper, or copper diffolved by any acid, may be difcovered by add. ing fome of the volatile fpirit of fal ammoniac, which produces a fine blue colour; or by the addition of clean iron, upon the furface of which the copper is precipitated in its natural or metallic ftate. Glauber's falt is discovered by adding a folution of mercury in nitrous acid, and forming with it a turbith mineral; or by cryftallization. Common falt contained in waters forms, with a folution of filver in nitrous acid, a white precipitate, or luna cornea. It may also be known by its cryf. tallization. Marine falt with earthy bafes produces the fame effect upon folution of filver; forming a precipitate when fixed alkali is added. Its acrimony, bitterness, and deliquefcency, diftinguish it. Vitriolic acid may be thus difcovered: The matter to be examined must be mixed with any inflammable, substance, and exposed to a red heat. If it contain but a particle of vitriolic acid, it will be rendered sensible by the fulphur, or by the volatile fulphureous acid thence produced. Any metallic fubftance, diffolved in water by an acid, may be detected by adding fome of the liquor faturated by the colouring matter of Pruffian blue. This liquor produces no effects upon neutral falts with earthy or alkaline bafes, but decompofes all metallic falts: fo that if no precipitate be formed upon adding fome of this liquor, we may be certain that the water does not contain any metallic falt; but if a precipitate be formed, we may cer. tainly infer that the water contains fome metallic falt. It is necessary to use no veffels in these experiments but fuch as are perfectly clean, and rinfed with diftilled water; to weigh the products very exactly; to make the experiments upon as large quantities of water as is poffible, efpecially the evaporations, crystallizations, and distillations; and to repeat all experiments feveral times. The mixtures, from which any precipitates might be expected, ought to be kept feveral days, as many of these precipitates require that time to appear, or to be entirely deposited.

(13.) MINERAL WATERS, MORE ACCURATE METHODS OF ANALYSING. "The analysis of waters (fays Dr Thomson), or the art of afcertaining the different fubftances they hold in folution, and determining their proportion, is one of the moft difficult things in chemistry. The difficulty arifes, not only from the diverfity of the bodies in waters, but from the very minute quantities of fome ingredients. Though many attempts had been made (§ 8.), no general mode was known till Bergman publifhed his treatise in 1778. This admirable tract carried the subject to a high degree

of perfection. The Bergmannian method has been followed by fucceeding chemifts. Mr Kirwan, in 1799, published an Effay on the general Analyfis of Waters, no less valuable than that of Bergman, and enriched by numerous experiments. He has given a new method of analyfis, not only fhorter and easier than the Bergmannian, but fufceptible of greater accuracy." Dr Thomfon gives an account of this method, of which our room permits us only to quote the outlines. "The different bodies diffolved and combined in water are difcovered by the addition of certain fubftances to the water, named tefts, which occafion fome change in the appearance of the water. I. The gafeous bodies contained in water are obtained by boiling it in a retort, luted to a pneumatic apparatus. II. Carbonic acid, not combined with a bafe, or combined in excefs, may be detected by the following tefts: 1. Lime water occafions a precipitate, foluble with effervefcence in muriatic acid. 2. The infufion of litmus is reddened, but the red gradually disappears. 3. When boiled, it lofes this property. III. The mineral acids, when uncombined, give the infufion of litmus a permanent red, though the water be boiled. IV. Water.containing fulphurated hydrogen gas is thus diftinguished: 1. It exhales the peculiar odour of that gas. 2. It reddens the infufion of litmus fugaciously. 3. It blackens paper dipt in folution of lead, and precipitates nitrat of filver black or brown. V. Alkalies, and alkaline and earthy carbonats, are thus diftinguished: 1. The infufion of turmeric is rendered brown. 2. Paper ftained with Brazil wood is rendered blue. 3. Litmus paper reddened by vinegar is restored to its original blue. 4. When thefe changes are fugacious, the alkali is ammonia. VI. Fixed alkalies exift in water, which occafions a precipitate with muriat of magnesia, after being boiled. Volatile alkali may be diftinguished by the fmell, or obtained by diftilling the water gently. VII. Earthy and metallic carbonats are precipitated by boiling the water; but carbonat of magnefia imperfectly. VIII. Iron is discovered by, 1. The tincture of nut-galls giving the water a purple or black colour; the gradations of which are diftinguished by Weftrum. 2. Pruffian alkali occafioning a blue precipitate. IX. Sulphuric acid exifts in waters, which form a precipitate with, 1. Muriât, nitrat, or acetite of barytes; 2. ditto of Strontian; 3. ditto of lime; 4. nitrat or acetite of lead. Of these the most powerful is muriat of barytes, which will detect fulphuric acid uncombined, when it is not the millionth part of the water. X. Muriatic acid is detected by nitrat of filver, which occafions a white cloud in water containing a very minute proportion of it. XI. Boracic acid is detected by acetite of lead, forming a precipitate infoluble in acetous acid. XII. Barytes is detected by the infoluble white precipitate it forms with diluted fulphuric acid. XIII. Lime is detected by oxalic acid, occafioning a white precipitate in water containing a very minute proportion of it. XIV. Magnesia and alumina are detected, 1. By ammonia precipitating them, if the carbonic acid has been previously feparated; 2. By lime water precipitating them, it the carbonic and fulphuric acids be previously removed. XV. Silica may be

afcertained

afcertained by evaporating a portion of the water to dryness, and rediffolving the precipitate in muriatic acid. The filica remains undiffolved. Such is the method of detecting the substances in waters; but as thefe are almost always combined fo as to form falts, Mr Kirwan pointed out tefts to detect thefe. I. 1. SULPHAT of foda may be detected by evaporating the water to one half, and adding lime-water, as long as any precipitate appears. 2. Sulphat of lime, by evaporating the water to a few ounces, when a precipitate appears foluble in 500 parts of water. 3. Alum may be detected by mixing carbonat of lime with the water, till a precipitate appears. 4 Sulphat of magnefia may be detected by hydrofulphuret of ftrontian, which occafions a precipitate with this falt and no other. 5. Sulphat of iron is precipitated by alcohol. II. I. MURIATS of foda and potafs may be detected thus: Separate the fulphuric acid by alcohol and nitrat of barytes. Decompofe the earthy nitrats and muriats by fulphuric acid. Expel the excess of muriatic and nitric acids by heat. Separate the fulphats thus formed by alcohol and barytic water. If it forms a precipitate with acetite of filver, it contains muriat of foda or potafs. To afcertain which, evaporate the liquid to drynefs; diffolve the acetite in alcohol. Evaporate to drynefs; the falt will deliquefce if it be acetite of potafs, but efflorefce if it be acetite of foda. 2. Muriat of barytes may be detected by fulphuric acid, as it is the only barytic falt found in waters. 3. Muriat of lime may be detected, by freeing the water of all fulphats; evaporating it to a few ounces, mixing it with fpirit of wine, and adding nitrat of barytes as long as any precipitate appears: filter off the water, evaporate to drynefs, treat the dry mass with alcohol: evaporate the alcohol, and diffolve the refiduum in water.--Similar proceffes are laid down, for detecting the muriats of magnefia and alumine, and the alkaline, calcareous, and magnefian nitrats; a table of falts incompatible with each other is also added, and a whole fection is allotted to the method of determining the proportion of the ingredients:-for all which, as well as for a number of minutia, to be observed in making fome of the above analyses, which our room permits us not to particularife, we must refer the reader to Dr Thomfon's work, or that of Mr Kirwan.

(14.) MINERAL WATERS, SUBSTANCES DISCOVERED IN. The fubftances met with in mineral waters are the following:-1. VITRIOLIC ACID, fometimes pure, though more frequent ly joined with iron or copper. In its pure ftate, it is ofteneft found near volcanoes, where, in the opinion of Dr Donald Monro, it is most probably "diftilled from mines of vitriol or of pyrites ftone, decompofed by fubterraneous fire." Dr Vandellius, in his work entitled, De Thermis Agri Patavini, 1761, mentions a cave near Latera 30 miles from Viterbo, in Italy, where a clear acid water drops from the crevices of the rocks. It has a mild agreeable tafte, and is a pure vitriolic acid much diluted. A fimilar native vitriolic water is mentioned by Theophilus Griffonius, near Salvena. Varenius mentions a fpring in Val di Noto in Sisily, the water of which is fo four, that the peoVOL. XV. PART I.

ple ufe it inftead of vinegar. In fome wafte coat pits, the water taftes four, and effervefces with alkalies. Dr Monro mentions acid dews collected in the Eaft Indies; this acid he supposes to be the vitriolic. 2. NITROUS and MURIATIC ACIDS are never found in waters pure, but combined with calcareous earths, foffile alkali, or magnefia. 3. FIXED AIR abounds in all mineral waters, particularly in fuch as are cold, to which it gives an agreeable acidulous tafte, as well as their power and efficacy. It is very often fufpended in wa ters by iron. Dr Dejean of Leyden, in a letter to Dr Monro in 1777, fuppofes it to be the medium by which fulphur alfo is diffolved. Many waters in Germany, particularly near the Rhine, are very much impregnated with this acid. 4. VEGE TABLE ALKALI was long fuppofed to be a production entirely artificial; but M. Margraaf got. a true nitre, the basis of which is the vegetable alkali, from fome waters at Berlin. M. Monnet fays, that from the Pohoun fpaw water he obtained 8 grains of a grey coloured alkaline falt from a refiduum of 12 Paris pints of the water, which he faturated with the vitriolic acid; and on diluting, evaporating, and cryftallizing, he obtained a tartarus vitriolatus. 5. The FOSSIL ALKALI is found in many waters in Hungary, Tripoti, Egypt, &c. It is combined in Seltzer and other acidulous wa. ters, with fixed air, and may be obtained from them pretty pure by fimple evaporation. In fome mineral waters near volcanoes, this alkali has been found capable of producing a true Pruffian blue, on adding a folution of filver or of green vitriol to the water; of which an example is given by Dr Nicholas Andrea, in the thermal waters of a fpring in the island of Ifchia. 6. VOLATILE ALKALI has been accounted an ingredient in mineral waters; but Dr Hoffman and others have denied this. But fome waters near great quanti ties of putrid matter may give tokens of volatile alkali, as was the cafe with Rathbone-plate water, analyfed by the Hon. Henry Cavendish. 7. GLAU. BER'S SALT is contained in many mineral waters, but the quantity is very fmall. M. Boulduc, in the Memoirs of the Academy of Sciences at Paris for 1724, mentions a fpring 9 miles from Madrid, which yields a true Glauber's falt. It is found in a concreted state about the fides of the spring, refembling icicles. Dr Andrea mentions a water at Sællia, in Calabria, which is very ftrongly impregnated with this falt. 8. NITRE. In fome provinces of Bengal, not only the waters, but even the earth, is fo ftrongly impregnated with nitre, that the furface is covered with a nitrous cruft refembling hoar-froft. Perfect nitre has ao been found in fprings in Europe. 9. SEA SALT abounds not only in the waters of the ocean, but in great numbers of falt fprings; and there are few waters fo pure as not to contain fome portion of it. AERATED FOSSILE ALKALI is found in Seltzer, and fimilar waters, but combined with fuch a quantity of fixed air, that the acrid tafte of the alkali is entirely covered. By evaporating the water, however, the alkali appears in its acrid ftate. II. GYPSUM, or SELENITES, is extremely common in mineral waters. It was long fuppofed to be a fimple earth or ftone, on account of its difficult folubility in water, requiring 700 or 800 times its B

10.

weight.

weight of water to diffolve it artificially. It is MANGANESE. Waters impregnated with this not, however, confidered as medicinal, nor is the falt are mentioned both by Bergman and Scheele. internal use of it thought fafe. 12. EPSOM SALT. 23. Arfenic has been fuppofed to be an ingredient Bergman and others have reduced all the calcare- in mineral waters, by Varenius and Dr Baldasiari. ous purging falts in which the vitriolic acid is con- 24. FOSSIL OILS. Álmoft all waters, even chofe cerned; but Dr Monro obferves, that thefe falts which are accounted pureft, contain fome portion not only cryftallize in various modes, but have of oil, though generally so fmall that it cannot be .different degrees of folubility in water.-The Ep- perceived without evaporating a large quantity of fom falt diffolves in an equal quantity of water; the liquid. A portion of it adheres fo very obftiwhile the calcareous nitres require from 10 to 80 nately, that it cannot be fully separated even by times their weight to diffolve them. Thefe falts, fiitration. A fine bituminous vapour rifes from however, are feldom met with by themfelves, but the bottom of fome wells, and pervades the ufually mixed with fea falt, iron, earth, fulphu- water, taking fire on the application of any reous matters, &c. Dr Rutty fays, that a mine- flaming fubftance, though no oil is obferved in ral water begins to be laxative when it contains the water itself. Of this kind are the burning ten grains of this falt to a pint, or 80 to a gallon. wells at Brofely and Wigan in Lancashire, and 13. ALUM was formerly fuppofed to be a very others in different countries.-The cause of the common ingredient in mineral waters; but more inflammation of thefe waters was firft discoveraccurate obfervations have shown it to be very ed, in 1759, by Mr Thomas Shirly, who caufed rare. Dr Hoffman thinks it is not to be met with the waters to be drained, and found that the inin any, but Dr Layard, in the Philof. Tranf. Vo!. flammable vapour rofe from the ground at the bot56, mentions a chalybeate water at Semerfham, tom, where it would take fire, as it did at the from which he got 5 gr. of alum out of 2 lb. of furface. On applying his hand to the place the water. 14 CALCAREUOS NITRE is rarely whence the vapour iffued, he found the impulfe found in mineral waters, though common in hard of it like a ftrong breath; and felt the fame fenwaters. Dr Monro fays, that the only one con- fation on applying it to the furface of the water. taining this ingredient, which he ever heard of, is See Philof. Tranf. Vol. 26. 25. SULPHUR is a ane mentioned by Dr Home, in his treatise on common ingredient in mineral waters, and is bleaching. 15. MURIATIC CALCAREOUS EARTH known by the ftrong hepatic fmell they emit, as is likewife a rare ingredient in mineral waters. well as by their blackening filver, &c. SulphuBergman fays, he obtained a small quantity from reous waters are often very clear and tranfparent a fpring in E. Gothland; and Dr Monro got fome when taken up, but, when kept in open vessels, from a falt fpring at Pitkeathly, near Perth. It depofit fulphur in the form of a dirty white pow. is found, as well as, 16. MURIATED MAGNESIA, der, and lofe their smell. The bottoms of the in fea water, though the latter is more abundant, wells containing fuch waters, or of the channels but not fo eafily obtained in a cryftalline form. in which they run, affume a black colour, and a Muriated magnesia is the chief ingredient in the raggy matter is depofited on such substances as bitter ley remaining after the falt is extracted from they run over for fome time. When these are tafea water, and is much more capable of being ken up and dried, they appear covered with fulcrystallized than the former. 17, 18. AERATED phur. Some waters contain fulphur in very conCALCAREOUS EARTH, and AERATED MAGNESIA, fiderable quantity. From that of Harrowgate it may be diffolved by fixed air, and often are fo in may be feparated by filtration; and F. De Termineral waters, as well as iron. They are alfo tre, in his Hiftoire Naturelle des Antilles, Vol. 2. often found in hard waters. When fuch waters tells us, that he found it in Guadaloupe, in a fulare boiled, the air evaporates, and the earth falls phureous water near the volcano. Dr Monro to the bottom. Hence originates the cruft upon obtained fulphur by evaporation, from a mineral tea-kettles, the petrefactions upon different fub. water at Cafle-Leod, in Rofs-fhire, in Scotland. ftances immerfed in fome kinds of water, &c. Dr Brown, in his Travels, informs us, that ha Hence alfo hard waters become foft, by running,ving caufed fome of the pipes which carry off the in channels. 19. Vitriolated copper is feldom found, except in waters which flow from copper mines. The water impregnated with it is emetic and pur. gative, and often poisonous. On dipping clean iron into fuch water, the copper is inftantly precipitated in its metallic ftate, and the iron diffolved in its ftead. 20. Vitriolated iron is found in confiderable quantity in several waters in England, Scotland, and Ireland, as well as in many countries on the continent. Some imagine, that there is a kind of volatile vitriol with which waters are fometimes impregnated. See a work entitled, Delle Terme Porretane, published at Rome in 1768. 21. VITRIOLATED ZINC has been found native in the earth; and thence has been fuppofed to be an ingredient in mineral waters. Dr Rutty and Dr Ginelin fay, that they have obtained a white vitriol from mineral waters which were also impregnated with iron and other ingredients. 22. MURIATED

water from the duke's bath at Baden, in Auftria, to be opened, he took thence a quantity of fine fulphur in powder. A fimilar fulphur is obtained from the upper part of the pipes which convey the waters of Aix-la-Chapelle. Dr Vandellius, in his treatife de Thermis agri Patavini, mentions a fubftance found in the conduits of the waters of the baths at Aponum, which he calls cryftallized fulphur, and fays that it diffolves in the waters by boiling, recovering afterwards its solid form.

(15.) MINERAL WATERS, SUBSTANCES FOUND IN, BY MODERN CHEMISTS. In the last section we have given a view, in as few words as poffible, of the fubftances difcovered in mineral waters, be fore the late improvements in chemistry; and have ftated them in the old chemical language, for the benefit of fuch readers as may not yet have become acquainted with the new chemical nomenclature. (See CHEMISTRY, Index, and Vo

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