REMARKS

FOOTNOTES:[1]The Times, May 18, 1818. The Kingv.Richard Bowman. The defendant was a brewer, living in Wapping-street, Wapping, and was charged with having in his possession a drug calledmultum, and a quantity of copperas.The articles were produced by Thomas Gates, an excise officer, who had, after a search, found them on the defendant's premises. The Court sentenced the defendant to pay a fine of 200l.The Kingv.Luke Lyons. The defendant is a brewer, and was brought up under an indictment charging him with having made use of various deleterious drugs in his brewery, among which were capsicum, copperas, &c. The defendant was ordered to pay the fines of 20l.upon the first count, 200l.upon the third, and 200l.upon the seventh count in the indictment.The Kingv.Thomas Evans. The charge against this defendant was, that he had in his possession forty-seven barrels of stale unpalatable beer. On, the 11th of March, John Wilson, an excise officer, went to the storehouse, and found forty-seven casks containing forty-three barrels and a half of sour unwholesome beer. Several samples of the beer were produced, all of them of a different colour, and filled with sediment. A fine of 30l.was ordered to be paid by the defendant.[2]Of this root, several varieties are imported. The white sort, which has no wrinkles, and no perceptible bitterness in taste, and which, though taken in a large dose, has scarcely any effect at all, after being pulverised by fraudulent druggists, and mixed with a portion of emetic tartar, is sold, at a low price, for the powder of genuine ipecacuanha root.[3]Genuine ultramarine should become deprived of its colour when thrown into concentrated nitric acid.[4]Genuine carmine should be totally soluble in liquid ammonia.[5]Genuine madder and carmine lakes should be totally soluble by boiling in a concentrated solution of soda or potash.[6]Genuine Antwerp blue should not become deprived of its colour when thrown into liquid chlorine.[7]Genuine chrome yellow should not effervesce with nitric acid.[8]The best Indian ink breaks, splintery, with a smooth glossy fracture, and feels soft, and not gritty, when rubbed against the teeth.[9]Genuine white lead should be completely soluble in nitric acid, and the solution should remain transparent when mingled with a solution of sulphate of soda.[10]Genuine vermilion should become totally volatilised on being exposed to a red heat; and it should not impart a red colour to spirit of wine, when digested with it.

FOOTNOTES:

[1]The Times, May 18, 1818. The Kingv.Richard Bowman. The defendant was a brewer, living in Wapping-street, Wapping, and was charged with having in his possession a drug calledmultum, and a quantity of copperas.The articles were produced by Thomas Gates, an excise officer, who had, after a search, found them on the defendant's premises. The Court sentenced the defendant to pay a fine of 200l.The Kingv.Luke Lyons. The defendant is a brewer, and was brought up under an indictment charging him with having made use of various deleterious drugs in his brewery, among which were capsicum, copperas, &c. The defendant was ordered to pay the fines of 20l.upon the first count, 200l.upon the third, and 200l.upon the seventh count in the indictment.The Kingv.Thomas Evans. The charge against this defendant was, that he had in his possession forty-seven barrels of stale unpalatable beer. On, the 11th of March, John Wilson, an excise officer, went to the storehouse, and found forty-seven casks containing forty-three barrels and a half of sour unwholesome beer. Several samples of the beer were produced, all of them of a different colour, and filled with sediment. A fine of 30l.was ordered to be paid by the defendant.

The articles were produced by Thomas Gates, an excise officer, who had, after a search, found them on the defendant's premises. The Court sentenced the defendant to pay a fine of 200l.

The Kingv.Luke Lyons. The defendant is a brewer, and was brought up under an indictment charging him with having made use of various deleterious drugs in his brewery, among which were capsicum, copperas, &c. The defendant was ordered to pay the fines of 20l.upon the first count, 200l.upon the third, and 200l.upon the seventh count in the indictment.

The Kingv.Thomas Evans. The charge against this defendant was, that he had in his possession forty-seven barrels of stale unpalatable beer. On, the 11th of March, John Wilson, an excise officer, went to the storehouse, and found forty-seven casks containing forty-three barrels and a half of sour unwholesome beer. Several samples of the beer were produced, all of them of a different colour, and filled with sediment. A fine of 30l.was ordered to be paid by the defendant.

[2]Of this root, several varieties are imported. The white sort, which has no wrinkles, and no perceptible bitterness in taste, and which, though taken in a large dose, has scarcely any effect at all, after being pulverised by fraudulent druggists, and mixed with a portion of emetic tartar, is sold, at a low price, for the powder of genuine ipecacuanha root.

[3]Genuine ultramarine should become deprived of its colour when thrown into concentrated nitric acid.

[4]Genuine carmine should be totally soluble in liquid ammonia.

[5]Genuine madder and carmine lakes should be totally soluble by boiling in a concentrated solution of soda or potash.

[6]Genuine Antwerp blue should not become deprived of its colour when thrown into liquid chlorine.

[7]Genuine chrome yellow should not effervesce with nitric acid.

[8]The best Indian ink breaks, splintery, with a smooth glossy fracture, and feels soft, and not gritty, when rubbed against the teeth.

[9]Genuine white lead should be completely soluble in nitric acid, and the solution should remain transparent when mingled with a solution of sulphate of soda.

[10]Genuine vermilion should become totally volatilised on being exposed to a red heat; and it should not impart a red colour to spirit of wine, when digested with it.

It requires not much reflection to become convinced that the waters which issue from the recesses of the earth, and form springs, wells, rivers, or lakes, often materially differ from each other in their taste and other obvious properties. There are few people who have not observed a difference in the waters used for domestic purposes and in the arts; and the distinctions ofhardandsoftwater are familiar to every body.

Water perfectly pure is scarcely ever met with in nature.

It must also be obvious, that the health and comfort of families, and the conveniences of domestic life, are materially affected by the supply of good and wholesome water. Hence a knowledge of the quality and salubrity of the different kinds of waters employed in the common concerns of life, on account of the abundant daily use we make of them in the preparation of food, is unquestionably an object of considerable importance, and demands our attention.

The effects produced by the foreign matters which water may contain, are more considerable, and of greater importance, than might at first be imagined. It cannot be denied, that such waters as arehard, or loaded with earthy matter, have a decided effect upon some important functions of the human body. They increase the distressing symptoms under which those persons labour who are afflicted with what is commonly called gravel complaints; and many other ailments might be named, that are always aggravated by the use of waters abounding in saline and earthy substances.

The purity of the waters employed in some of the arts and manufactures, is an object of not less consequence. In the process of brewing malt liquors, soft water ispreferable to hard. Every brewer knows that the largest possible quantity of the extractive matter of the malt is obtained in the least possible time, and at the smallest cost, by means of soft water.

In the art of the dyer, hard water not only opposes the solution of several dye stuffs, but it also alters the natural tints of some delicate colours; whilst in others again it precipitates the earthy and saline matters with which it is impregnated, into the delicate fibres of the stuff, and thus impedes the softness and brilliancy of the dye.

The bleacher cannot use with advantage waters impregnated with earthy salts; and a minute portion of iron imparts to the cloth a yellowish hue.

To the manufacturer of painters' colours, water as pure as possible is absolutely essential for the successful preparation of several delicate pigments. Carmine, madder lake, ultramarine, and Indian yellow, cannot be prepared without perfectly pure water.

For the steeping or raiting of flax, soft water is absolutely necessary; in hard water the flax may be immersed for months, till its texture be injured, and still the ligneous matter will not be decomposed, and the fibres properly separated.

In the culinary art, the effects of watermore or less pure are likewise obvious. Good and pure water softens the fibres of animal and vegetable matters more readily than such as is calledhard. Every cook knows that dry or ripe pease, and other farinaceous seeds, cannotreadilybe boiled soft in hard water; because the farina of the seed is not perfectly soluble in water loaded with earthy salts.

Green esculent vegetable substances are more tender when boiled in soft water than in hard water; although hard water imparts to them a better colour. The effects of hard and soft water may be easily shown in the following manner.

EXPERIMENT.

Let two separate portions of tea-leaves be macerated, by precisely the same processes, in circumstances all alike, in similar and separate vessels, the one containing hard and the other soft water, either hot or cold, the infusion made with the soft water will have by far the strongest taste, although it possesses less colour than the infusion made with the hard water. It will strike a more intense black with a solution of sulphate of iron, and afford a more abundantprecipitate, with a solution of animal jelly, which at once shews that soft water has extracted more tanning matter, and more gallic acid, from the tea-leaves, than could be obtained from them under like circumstances by means of hard water.

Many animals which are accustomed to drink soft water, refuse hard water. Horses in particular prefer the former. Pigeons refuse hard water when they have been accustomed to soft water.

CHARACTERS OF GOOD WATER.

A good criterion of the purity of water fit for domestic purposes, is its softness. This quality is at once obvious by the touch, if we only wash our hands in it with soap. Good water should be beautifully transparent; a slight opacity indicates extraneous matter. To judge of the perfect transparency of water, a quantity of it should be put into a deep glass vessel, the larger the better, so that we can look down perpendicularly into a considerable mass of the fluid; we may then readily discover the slightest degree of muddiness much better than if the water be viewed through the glass placed between the eye and the light. Itshould be perfectly colourless, devoid of odour, and its taste soft and agreeable. It should send out air-bubbles when poured from one vessel into another; it should boil pulse soft, and form with soap an uniform opaline fluid, which does not separate after standing for several hours.

It is to the presence of common air and carbonic acid gas that common water owes its taste, and many of the good effects which it produces on animals and vegetables. Spring water, which contains more air, has a more lively taste than river water.

Hence the insipid or vapid taste of newly boiled water, from which these gases are expelled: fish cannot live in water deprived of those elastic fluids.

100 cubic inches of the New River water, with which part of this metropolis is supplied, contains 2,25 of carbonic acid, and 1,25 of common air. The water of the river Thames contains rather a larger quantity of common air, and a smaller portion of carbonic acid.

If water not fully saturated with common air be agitated with this elastic fluid, a portion of the air is absorbed; but the two chief constituent gases of the atmosphere, the oxygen and nitrogen, are notequally affected, the former being absorbed in preference to the latter.

According to Mr. Dalton, in agitating water with atmospheric air, consisting of 79 of nitrogen, and 21 of oxygen, the water absorbs 1/64 of 79/100 nitrogen gas = 1,234, and 1/27 of 21/100 oxygen gas = 778, amounting in all to 2,012.

Water is freed from foreign matter by distillation: and for any chemical process in which accuracy is requisite, distilled water must be used.

Hard waters may, in general, be cured in part, by dropping into them a solution of sub-carbonate of potash; or, if the hardness be owing only to the presence of super-carbonate of lime, mere boiling will greatly remedy the defect; part of the carbonic acid flies off, and a neutral carbonate of lime falls down to the bottom; it may then be used for washing, scarcely curdling soap. But if the hardness be owing in part to sulphate of lime, boiling does not soften it at all.

When spring water is used for washing, it is advantageous to leave it for some time exposed to the open air in a reservoir with a large surface. Part of the carbonic acid becomes thus dissipated, and part of the carbonate of lime falls to the bottom. Mr.Dalton[11]has observed that the more any spring is drawn from, the softer the water becomes.

CHEMICAL CONSTITUTION OF THE WATERS USED IN DOMESTIC ECONOMY AND THE ARTS.

Rain Water,

Collected with every precaution as it descends from the clouds, and at a distance from large towns, or any other object capable of impregnating the atmosphere with foreign matters, approaches more nearly to a state of purity than perhaps any other natural water. Even collected under these circumstances, however, it invariably contains a portion of common air and carbonic acid gas. The specific gravity of rain water scarcely differs from that of distilled water; and from the minute portions of the foreign ingredients which it generally contains, it is verysoft, and admirably adapted formany culinary purposes, and various processes in different manufactures and the arts.

Fresh-fallensnow, melted without the contact of air, appears to be nearly free from air. Gay-Lussac and Humboldt, however, affirm, that it contains nearly the usual proportion of air.

Water from meltedicedoes not contain so much air.Dewhas been supposed to be saturated with air.

Snow water has long laid under the imputation of occasioning those strumous swellings in the neck which deform the inhabitants of many of the Alpine vallies; but this opinion is not supported by any well-authenticated indisputable facts, and is rendered still more improbable, if not entirely overturned, by the frequency of the disease in Sumatra[12], where ice and snow are never seen.

In high northern latitudes, thawed snow forms the constant drink of the inhabitants during winter; and the vast masses of ice which float on the polar seas, afford an abundant supply of fresh water to the mariner.

Spring Water,

Includes well-water and all others that arise from some depth below the surface of the earth, and which are used at the fountain-head, or at least before they have run any considerable distance exposed to the air. Indeed, springs may be considered as rain water which has passed through the fissures of the earth, and, having accumulated at the bottom of declivities, rises again to the surface forming springs and wells. As wells take their origin at some depth from the surface, and below the influence of the external atmosphere, their temperature is in general pretty uniform during every vicissitude of season, and always several degrees lower than the atmosphere. They differ from one another according to the nature of the strata through which they issue; for though the ingredients usually existing in them are in such minute quantities as to impart to the water no striking properties, and do not render it unfit for common purposes, yet they modify its nature very considerably. Hence the water of some springs is said to behard, of otherssoft, somesweet, othersbrackish, accordingto the nature and degree of the inpregnating ingredients.

Common springs are insensibly changed into mineral or medicinal springs, as their foreign contents become larger or more unusual; or, in some instances, they derive medicinal celebrity from the absence of those ingredients usually occurring in spring-water; as, for example, is the case with the Malvern spring, which is nearly pure water.

Almost all spring-waters possess the property termedhardnessin a greater or less degree; a property which depends chiefly upon the presence of super-carbonate, or of sulphate of lime, or of both; and the quantity of these earthy salts varies very considerably in different instances. Mr. Dalton[13]has shewn that one grain of sulphate of lime, contained in 2000 grains of water, converts it into the hardest spring water that is commonly met with.

The waters of deep wells are usually much harder than those of springs which overflow the mouth of the well; but there are some exceptions to this rule.

The purest springs are those which occurin primitive rocks, or beds of gravel, or filter through sand or silicious strata. In general, large springs are purer than small ones: and our old wells contain finer water than those that are new, as the soluble parts through which the water filters in channels under ground become gradually washed away.

River Water,

Is a term applied to every running stream or rivulet exposed to the air, and always flowing in an open channel. It is formed of spring water, which, by exposure, becomes more pure, and of running land or surface water, which, although turbid from particles of the alluvial soil suspended in it, is otherwise very pure. It is purest when it runs over a gravelly or rocky bed, and when its course is swift. It is generally soft, and more free from earthy salts than spring water; but it usually contains less common air and carbonic acid gas; for, by the agitation of a long current, and exposed to the temperature of the atmosphere, part of its carbonic acid gas is disengaged, and the lime held in solution by it is in part precipitated, the loss of which contributes to the softness of the water. Its specific gravity therebybecomes less, the taste not so harsh, but less fresh and agreeable; and out of a hard spring is often made a stream of sufficient purity for most of the purposes where a soft water is required.

The water called in this metropolisNew River Water, contains a minute portion of muriate of lime, carbonate of lime, and muriate of soda.

Some streams, however, that arise from clean silicious beds, and flow in a sandy or stony channel, are from the outset remarkably pure; such as the mountain lakes and rivulets in the rocky districts of Wales, the source of the beautiful waters of the Dee, and numberless other rivers that flow through the hollow of every valley. Switzerland has long been celebrated for the purity and excellence of its waters, which pour in copious streams from the mountains, and give rise to the finest rivers in Europe.

Some rivers, however, that do not take their rise from a rocky soil, and are indeed at first considerably charged with foreign matter, during a long course, even over a richly cultivated plain, become remarkably pure as to saline contents; but often fouled with mud containing much animal and vegetable matter, which are rather suspendedthan held in true solution. Such is the water of the river Thames, which, taken up at London at low water mark, is very soft and good; and, after rest, it contains but a very small portion of any thing that could prove pernicious, or impede any manufacture. It is also excellently fitted for sea-store; but it then undergoes a remarkable spontaneous change, when preserved in wooden casks. No water carried to sea becomes putrid sooner than that of the Thames. But the mode now adopted in the navy of substituting iron tanks for wooden casks, tends greatly to obviate this disadvantage.

Whoever will consider the situation of the Thames, and the immense population along its banks for so many miles, must at once perceive the prodigious accumulation of animal matters of all kinds, which by means of the common sewers constantly make their way into it. These matters are, no doubt, in part the cause of the putrefaction which it is well known to undergo at sea, and of the carburetted and sulphuretted hydrogen gases which are evolved from it. When a wooden cask is opened, after being kept a month or two, a quantity of carburetted and sulphuretted hydrogen escapes, and the water is so black and offensive as scarcelyto be borne. Upon racking it off, however, into large earthen vessels, and exposing it to the air, it gradually deposits a quantity of black slimy mud, becomes clear as crystal, and remarkably sweet and palatable.

It might, at first sight, be expected that the water of the Thames, after having received all the contents of the sewers, drains, and water courses, of a large town, should acquire thereby such impregnation with foreign matters, as to become very impure; but it appears, from the most accurate experiments that have been made, that those kinds of impurities have no perceptible influence on the salubrious quality of a mass of water so immense, and constantly kept in motion by the action of the tides.

Some traces of animal matter may, however, be detected in the water of the Thames; for if nitrate of lead be dropped into it,[14]"you will find that it becomes milky, and that a white powder falls to the bottom, which dissolves without effervescencein nitric acid. It is, therefore, (says Dr. Thomson) a combination of oxide of lead with some animal matter."

SUBSTANCES USUALLY CONTAINED IN COMMON WATER, AND TESTS BY WHICH THEY ARE DETECTED.

To acquire a knowledge of the general nature of common water, it is only necessary to add to it a few chemical tests, which will quickly indicate the presence or absence of the substances that may be expected.

Almost the only salts contained in common waters are the carbonates, sulphates, and muriates of soda, lime, and magnesia; and sometimes a very minute portion of iron may also be detected in them.

EXPERIMENT.

Fill a wine-glass with distilled water, and add to it a few drops of a solution of soap in alcohol, the water will remain transparent.

This test is employed for ascertaining the presence of earthy salts in waters.Hence it produces no change when mingled with distilled or perfectly pure water; but when added to water containing earthy salts, a white flocculent matter becomes separated, which speedily collects on the surface of the fluid. Now, from the quantity of flocculent matter produced, in equal quantities of water submitted to the test, a tolerable notion may be formed of the degrees of hardness of different kinds of water, at least so far as regards the fitness of the water for the ordinary purposes of domestic economy. This may be rendered obvious in the following manner.

EXPERIMENT.

Fill a number of wine-glasses with different kinds of pump or well water, and let fall into each glass a few drops of the solution of soap in alcohol. A turbidness will instantly ensue, and a flocculent matter collect on the surface of the fluid, if the mixture be left undisturbed. The quantity of flocculent matter will be in the ratio of the quantity of earthy salts contained in the water.

It is obvious that the action of this test is not discriminative, with regard to thechemical nature of the earthy salt present in the water. It serves only to indicate thepresenceorabsenceof those kinds of substances which occasion that quality in water which is usually calledhardness, and which is always owing to salts with an earthy base.

If we wish to know the nature of the different acids and earths contained in the water, the following test may be employed.[15]

EXPERIMENT.

Add about twenty drops of a solution of oxalate of ammonia, to half a wine-glass of the water; if a white precipitate ensues, we conclude that the water contains lime.

By means of this test, one grain of lime may be detected in 24,250 of water.

If this test occasion a white precipitate in water taken fresh from the pump or spring, and not after the water has been boiled and suffered to grow cold, the lime is dissolved in the water by an excess ofcarbonic acid; and if it continues to produce a precipitate in the water which has been concentrated by boiling, we then are sure that the lime is combined with a fixed acid.

EXPERIMENT.

To detect the presence of iron, add to a wine-glassful of the water a few drops of an infusion of nut-galls; or better, suffer a nut-gall to be suspended in it for twenty-four hours, which will cause the water to acquire a blueish black colour, if iron be present.

EXPERIMENT.

Add a few grains of muriate of barytes, to half a wine-glass of the water to be examined; if it produces a turbidness which does not disappear by the admixture of a few drops of muriatic acid, the presence of sulphuric acid is rendered obvious.

EXPERIMENT.

If a few drops of a solution of nitrate of silver occasions a milkiness with the water,which vanishes again by the copious addition of liquid ammonia, we have reason to believe that the water contains a salt, one of the constituent parts of which is muriatic acid.

EXPERIMENT.

If lime water or barytic water occasions a precipitate which again vanishes by the admixture of muriatic acid, then carbonic acid is present in the water.

EXPERIMENT.

If a solution of phosphate of soda produces a milkiness with the water, after a previous addition to it of a similar quantity of neutral carbonate of ammonia, we may then expect magnesia. The application of this test is best made in the following manner:

Concentrate a quantity of the water to be examined to about 1/20 part of its bulk, and drop into about half a wine-glassful, about five grains of neutral carbonate of ammonia. No magnesia becomes yet precipitated if this earth be present; but on adding a like quantity of phosphate of soda,the magnesia falls down, as an insoluble salt. It is essential that the carbonate of ammonia be neutral.

This test was first pointed out by Dr. Wollaston.

The presence of oxygen gas loosely combined in water may readily be discovered in the following manner.

EXPERIMENT.

Fill a vial with water, and add to it a small quantity of green sulphate of iron. If the water be entirely free of oxygen, and if the vessel be well stopped and completely filled, the solution is transparent; but if otherwise, it soon becomes slightly turbid, from the oxide of iron attracting the oxygen, and a small portion of it, in this more highly oxidated state, leaving the acid and being precipitated. Or, according to a method pointed out by Driessen, the water is to be boiled for two hours in a flask filled with it, and immersed in a vessel of water kept boiling, with the mouth of the flask under the surface of the water: it is to be inverted in quicksilver, taking care that no air-bubble adheres to the side of the flask, and being tinged with infusion of litmus, alittle nitrous gas is to be introduced: if the oxygen gas has been sufficiently expelled from the water, the purple colour of the litmus does not change; while, if oxygen be present, it immediately becomes red.[16]

If we examine the different waters which are used for the ordinary purposes of life, and judge of them by the above tests, we shall find them to differ considerably from each other. Some contain a large quantity of saline and earthy matters, whilst others are nearly pure. The differences are produced by the great solvent power which water exercises upon most substances. Wells should never be lined with bricks, which render soft water hard; or, if bricks be employed, they should be bedded in and covered with cement.

METHOD OF ASCERTAINING THE RELATIVE QUANTITY OF EACH OF THE DIFFERENT SUBSTANCES USUALLY CONTAINED IN COMMON WATER.

To ascertain the quantity of earthy and saline matter contained in water, the following is the most simple and easy method.

EXPERIMENT.

Put any measured quantity of the water into a platina, or silver evaporating basin, the weight of which is known, and evaporate the water upon a steam bath, at a temperature of about 180°, nearly to dryness; and, lastly, remove the basin to a sand bath, and let the mass be evaporated to perfect dryness. The weight of the platina basin being already known, we have only to weigh it carefully. When the solid saline contents of the water is attached to it, the increase of weight gives the quantity of solid matter contained in a given quantity of the water.

EXPERIMENT.

Pour upon the saline contents a quantity of distilled water equal to that in which the obtained salts were originally dissolved. If the whole saline matter become dissolved in this water, there is reason to believe that the saline matter has not been altered during the evaporation of the water. But if a portion remain undissolved, as is usually the case, then we may conclude that some of the salts have mutually decomposedeach other, when brought into a concentrated state by the evaporation, and that salts have been formed which did not originally exist in the water before its evaporation.

We have already mentioned that almost the only salts contained in common waters, are the carbonates, sulphates, and muriates, of soda, lime, and magnesia; and sometimes a very minute portion of iron. Having determined the different acids and bases present, in the manner stated at p. 49, we may easily ascertain the relative weight of each.

The following formula suggested by Dr. Murray,[17]is fully as accurate a means of analysing waters as any other, and it is easy of execution. The weight of the saline ingredients of a given quantity of water being determined, we may proceed to the accurate analysis of it in the following manner.

EXPERIMENT.

Measure out a determinate volume of thewater (as 500 or 1000 cubic inches,) and evaporate it gradually, in an unglazed open vessel defended from dust, to one third of its original bulk; then divide this evaporated liquid into three equal portions.

EXPERIMENT.

Drop into the first portion, muriate of barytes; wash the precipitate, collect it, dry it at a red heat upon platina foil, and weigh it; digest it in nitric acid, dry it, and weigh it again. The loss of weight indicates the quantity of carbonate of barytes which the precipitate contained. The residual weight is sulphate of barytes; the carbonic acid in the water is equivalent to 0,22 of the weight of the carbonate of barytes; the sulphuric acid to 0,339 of the weight of the sulphate of barytes.

EXPERIMENT.

Precipitate the second portion of the concentrated water, by the addition of nitrate of silver; wash the precipitate, dry it, and fuse it on a piece of foil platina, previously weighed. By weighing the foil containingthe fused chloride of silver, the weight of the precipitate may be ascertained. The fourth part of this weight is equivalent to the weight of the muriatic acid contained in the portion of water precipitated.

EXPERIMENT.

Precipitate the third portion of the water by the addition of oxalate of ammonia; wash and dry the precipitate; expose it to a red heat, on a platina foil, or in a capsule of platina; pour on it some dilute sulphuric acid; digest for some time, then evaporate to dryness, expose the capsule to a pretty strong heat, and, lastly, weigh the sulphate of lime thus produced: 0.453 of its weight indicate the quantity of lime in the portion of water precipitated.

EXPERIMENT.

Add to the same third portion of the water thus freed from lime, a portion of a solution of neutral carbonate of ammonia, and then add phosphoric acid, drop by drop, as long as any precipitate falls down. Wash the precipitate, dry it, and expose it to ared heat in a platina capsule: it is phosphate of magnesia. 0.357 of the weight of this salt is equivalent to the weight of the magnesia contained in the water.

EXPERIMENT.

If the water contain a minute portion of iron, a quantity of it equal to one of the three preceding portions, must be taken and mixed with a solution of benzoate of ammonia. The precipitate being washed, dried, and exposed to a red heat, and weighed, nine-tenths of its weight indicate the weight of protoxide of iron contained in the water.

In this manner the quantity of all the substances contained in the water will be ascertained, except there be any soda. To know the amount of it, the following method, pointed out by Dr. Murray, answers very well.

EXPERIMENT.

Evaporate a portion of the water to one third of its bulk. Precipitate the carbonic and sulphuric acids by the addition of muriate of barytes, taking care not to add any excess of the tests.

Precipitate the lime by oxalate of ammonia, and the magnesia by carbonate of ammonia and phosphoric acid. (Page52.) Then evaporate the liquid thus treated to dryness. A quantity of common salt will remain: let this be exposed to a red heat; 0.4 of its weight indicate the sodium contained in the bulk of water employed; and 0.4 sodium are equivalent to 0.53 of soda.

It seems hardly requisite to mention some other substances that occasionally make their appearance in the waters used for domestic purposes. A fine divided sand is a common constituent, which is easily obtained in a separate state. We have only to evaporate a portion of the water to dryness, and redissolve the saline residue in distilled water. The silicious sand remains undissolved, and betrays itself by its insolubility in acids, and its easy fusibility into a transparant glass, with soda, before the blow-pipe.

DELETERIOUS EFFECTS OF KEEPING WATER FOR DOMESTIC ECONOMY IN LEADEN RESERVOIRS.

The deleterious effect of lead, when taken into the stomach, is at present so universally known, that it is quite unnecessaryto adduce any argument in proof of its dangerous tendency.

The ancients were, upwards of 2000 years ago, as well aware of the pernicious quality of this metal as we are at the present day; and indeed they appeared to have been much more apprehensive of its effects, and scrupulous in the application of it to purposes of domestic economy.

Their precautions may have been occasionally carried to an unnecessary length. This was the natural consequence of the imperfect state of experimental knowledge at that period. When menwereunable to detect the poisonous matters—to be over scrupulous in the use of such water, was an error on the right side.

The moderns, on the other hand, in part, perhaps, from an ill-founded confidence, and inattention to a careful and continued examination of its effects, have fallen into an opposite error.

There can be no doubt that the mode of preserving water intended for food or drink in leaden reservoirs, is exceedingly improper; and although pure water exercises no sensible action upon metallic lead, provided air be excluded, the metal is certainly acted on by the water when air is admitted: thiseffect is so obvious, that it cannot escape the notice of the least attentive observer.

The white line which may be seen at the surface of the water preserved in leaden cisterns, where the metal touches the water and where the air is admitted, is a carbonate of lead, formed at the expense of the metal. This substance, when taken into the stomach, is highly deleterious to health. This was the reason which induced the ancients to condemn leaden pipes for the conveyance of water; it having been remarked that persons who swallowed the sediment of such water, became affected with disorders of the bowels.[18]

Leaden water reservoirs were condemned in ancient times by Hyppocrates, Galen,andVitruvius, as dangerous: in addition to which, we may depend on the observations of Van Swieten, Tronchin, and others, who have quoted numerous unhappy examples of whole families poisoned by water which had remained in reservoirs of lead. Dr. Johnston, Dr. Percival, Sir George Baker, and Dr. Lamb, have likewise recorded numerous instances where dangerous diseases ensued from the use of water impregnated with lead.

Different potable waters have unequal solvent powers on this metal. In some places the use of leaden pumps has been discontinued, from the expense entailed upon the proprietors by the constant want of repair. Dr. Lamb[19]states an instance where the proprietor of a well ordered his plumber to make the lead of a pump of double the thickness of the metal usually employed for pumps, to save the charge of repairs; because he had observed that the water was so hard, as he called it, that it corroded the lead very soon.

The following instance is related by Sir George Baker:[20]

"A gentleman was the father of a numerous offspring, having had one-and-twenty children, of whom eight died young, and thirteen survived their parents. During their infancy, and indeeduntil they had quitted the place of their usual residence, they were all remarkably unhealthy; being particularly subject to disorders of the stomach and bowels. The father, during many years, was paralytic; the mother, for a long time, was subject to colics and bilious obstructions.

"After the death of the parents, the family sold the house which they had so long inhabited. The purchaser found it necessary to repair the pump. This was made of lead; which, upon examination was found to be so corroded, that several perforations were observed in the cylinder, in which the bucket plays; and the cistern in the upper part was reduced to the thinness of common brown paper, and was full of holes, like a sieve."

I have myself seen numerous instances where leaden cisterns have been completely corroded by the action of water with which they were in contact: and there is, perhaps, not a plumber who cannot give testimony of having experienced numerous similar instances in the practice of his trade.

I have been frequently called upon to examine leaden cisterns, which had become leaky on account of the action of the water which they contained; and I could adduce an instance of a legal controversy having taken place to settle the disputes between the proprietors of an estate and a plumber, originating from a similar cause—the plumber being accused of having furnished a faulty reservoir; whereas the case was proved to be owing to the chemical action of the water on the lead. Water containinga large quantity of common air and carbonic acid gas, always acts very sensibly on metallic lead.

Water, which has no sensible action, in its natural state, upon lead, may acquire the capability of acting on it by heterogeneous matter, which it may accidentally receive. Numerous instances have shewn that vegetable matter, such as leaves, falling into leaden cisterns filled with water, imparted to the water a considerable solvent power of action on the lead, which, in its natural state it did not possess. Hence the necessity of keeping leaden cisterns clean; and this is the more necessary, as their situations expose them to accidental impurities. The noted saturnine colic of Amsterdam, described by Tronchin, originated from such a circumstance; as also the case related by Van Swieten,[21]of a whole family afflicted with the same complaint, from such a cistern. And it is highly probable that the case of disease recorded by Dr. Duncan,[22]proceeded more from some foulness in the cistern, than from the solventpower of the water. In this instance the officers of the packet boat used water for their drink and cooking out of a leaden cistern, whilst the sailors used the water taken from the same source, except that theirs was kept in wooden vessels. The consequence was, that all the officers were seized with the colic, and all the men continued healthy.

The carelessness of the bulk of mankind, Dr. Lambe very justly observes, to these things, "is so great, that to repeat them again and again cannot be wholly useless."

Although the great majority of persons who daily use water kept in leaden cisterns receive no sensible injury, yet the apparent salubrity must be ascribed to the great slowness of its operation, and the minuteness of the dose taken, the effects of which become modified by different causes and different constitutions, and according to the predisposition to diseases inherent in different individuals. The supposed security of the multitude who use the water with impunity, amounts to no more than presumption, in favour of any individual, which may or may not be confirmed by experience.

Independent of the morbid susceptibilityof impressions which distinguish certain habits, there is, besides, much variety in the original constitution of the human frame, of which we are totally ignorant.

"The susceptibility or proneness to disease of each individual, must be esteemed peculiar to himself. Confiding to the experience of others is a ground of security which may prove fallacious; and the danger can with certainty be obviated only by avoiding its source. And considering the various and complicated changes of the human frame, under different circumstances and at different ages, it is neither impossible nor improbable that the substances taken into the system at one period, and even for a series of years, with apparent impunity may, notwithstanding, at another period, be eventually the occasion of disease and of death.

"The experience of a single person, or of many persons, however numerous, is quite incompetent to the decision of a question of this nature.

"The pernicious effects of an intemperate use of spiritous liquors is not less certain because we often see habitual drunkards enjoy a state of good health, and arrive at old age: and the same may be said of individuals who indulge in vices of all kinds,evidently destructive to life; many of whom, in spite of their bad habits, attain to a vigorous old age."[23]

In confirmation of these remarks, we adduce the following account of the effect of water contaminated by lead, given by Sir G. Baker:

"The most remarkable case on the subject that now occurs to my memory, is that of Lord Ashburnham's family, in Sussex; to which, spring water was supplied, from a considerable distance, in leaden pipes. In consequence, his Lordship's servants were every year tormented with colic, and some of them died. An eminent physician, of Battle, who corresponded with me on the subject, sent up some gallons of that water, which were analysed by Dr. Higgins, who reported that the water had contained more than the common quantity of carbonic acid; and that he found in it lead in solution, which he attributed to the carbonic acid. In consequence of this, Lord Ashburnham substituted wooden for leaden pipes; and from that time his family have had no particular complaints in their bowels."

Richmond, Sept. 27, 1802.

METHOD OF DETECTING LEAD, WHEN CONTAINED IN WATER.

One of the most delicate tests for detecting lead, is water impregnated with sulphuretted hydrogen gas, which instantly imparts to the fluid containing the minutest quantity of lead, a brown or blackish tinge.

This test is so delicate that distilled water, when condensed by a leaden pipe in a still tub, is affected by it. To shew the action of this test, the following experiments will serve.

EXPERIMENT.

Pour into a wine-glass containing distilled water, an equal quantity of water impregnated with sulphuretted hydrogen gas: no change will take place; but if a 1/4 of a grain of acetate of lead (sugar of lead of commerce), or any other preparation of lead, be added, the mixture will instantly turn brown and dark-coloured.

To apply this test, one part of the suspected water need merely to be mingled with a like quantity of water impregnated with sulphuretted hydrogen. Or better, alarger quantity, a gallon for example, of the water may be concentrated by evaporation to about half a pint, and then submitted to the action of the test.

Another and more efficient mode of applying this test, is, to pass a current of sulphuretted hydrogen gas through the suspected water in the following manner.

EXPERIMENT.

Take a bottle (a) or Florence flask, adapt to the mouth of it a cork furnished with a glass tube (b), bent at right angles; let one leg of the tube be immersed in the vial (c) containing the water to be examined; as shewn in the following sketch. Then take one part of sulphuret of antimony of commerce, break it into pieces of half the size of split pease, put it into the flask, andpour upon it four parts of common concentrated muriatic acid (spirit of salt of commerce). Sulphuretted hydrogen gas will become disengaged from the materials in abundance, and pass through the water in the vial (c). Let the extrication of the gas be continued for about five minutes; and if the minutest quantity of lead be present, the water will acquire a dark-brown or blackish tinge. The extrication of the gas is facilitated by the application of a gentle heat.

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