Part 2

To ascertain the purity of magnesia, add to a portion of it a little sulphuric acid, diluted with ten times its bulk of water. If the magnesia be completely soluble, and the solution remains transparent, it may be pronounced _pure_; but not otherwise. Or, dissolve a portion of the magnesia in muriatic acid, and add a solution of sub-carbonate of ammonia. If any lime be present, it will form a precipitate; whereas pure magnesia will remain in solution.

Calcined magnesia is seldom met with in a pure state. It may be assayed by the same tests as the common magnesia. It ought not to effervesce at all, with dilute sulphuric acid; and, if the magnesia and acid be put together into one scale of a balance, no diminution of weight should ensue on mixing them together. Calcined magnesia, however, is very seldom so pure as to be totally dissolved by diluted sulphuric acid; for a small insoluble residue generally remains, consisting chiefly of silicious earth, derived from the alkali employed in the preparation of it. The solution in sulphuric acid, when largely diluted, ought not to afford any precipitation by the addition of oxalate of ammonia.

The genuineness of calomel may be ascertained by boiling, for a few minutes, one part, with 1/32 part of muriate of ammonia in ten parts of distilled water. When carbonate of potash is added to the filtered solution, no precipitation will ensue if the calomel be pure.

Indeed, some of the most common and cheap drugs do not escape the adulterating hand of the unprincipled druggist. Syrup of buckthorn, for example, instead of being prepared from the juice of buckthorn berries, (_rhamnus catharticus_,) is made from the fruit of the blackberry bearing alder, and the dogberry tree. A mixture of the berries of the buckthorn and blackberry bearing alder, and of the dogberry tree, may be seen publicly exposed for sale by some of the venders of medicinal herbs. This abuse may be discovered by opening the berries: those of buckthorn have almost always four seeds; of the alder, two; and of the dogberry, only one. Buckthorn berries, bruised on white paper, stain it of a green colour, which the others do not.

Instead of worm-seed (_artemisia santonica_,) the seeds of tansy are frequently offered for sale, or a mixture of both.

A great many of the essential oils obtained from the more expensive spices, are frequently so much adulterated, that it is not easy to meet with such as are at all fit for use: nor are these adulterations easily discoverable. The grosser abuses, indeed, may be readily detected. Thus, if the oil be adulterated with alcohol, it will turn milky on the addition of water; if with expressed oils, alcohol will dissolve the volatile, and leave the other behind; if with oil of turpentine, on dipping a piece of paper in the mixture, and drying it with a gentle heat, the turpentine will be betrayed by its smell. The more subtile artists, however, have contrived other methods of sophistication, which elude all trials. And as all volatile oils agree in the general properties of solubility in spirit of wine, and volatility in the heat of boiling water, &c. it is plain that they may be variously mixed with each other, or the dearer sophisticated with the cheaper, without any possibility of discovering the abuse by any of the before-mentioned trials. Perfumers assert that the smell and taste are the only certain tests of which the nature of the thing will admit. For example, if a bark should have in every respect the appearance of good cinnamon, and should be proved indisputably to be the genuine bark of the cinnamon tree; yet if it want the cinnamon flavour, or has it but in a low degree, we reject it: and the case is the same with the essential oil of cinnamon. It is only from use and habit, or comparisons with specimens of known quality, that we can judge of the goodness, either of the drugs themselves, or of their oils.

Most of the arrow-root, the fecula of the Maranta arudinacea, sold by druggists, is a mixture of potatoe starch and arrow-root.

The same system of adulteration extends to articles used in various trades and manufactures. For instance, linen tape, and various other household commodities of that kind, instead of being manufactured of linen thread only, are made up of linen and cotton. Colours for painting, not only those used by artists, such as ultramarine,[3] carmine,[4] and lake;[5] Antwerp blue,[6] chrome yellow,[7] and Indian ink;[8] but also the coarser colours used by the common house-painter are more or less adulterated. Thus, of the latter kind, white lead[9] is mixed with carbonate or sulphate of barytes; vermilion[10] with red lead.

Soap used in house-keeping is frequently adulterated with a considerable portion of fine white clay, brought from St. Stephens, in Cornwall. In the manufacture of printing paper, a large quantity of plaster of Paris is added to the paper stuff, to increase the weight of the manufactured article. The selvage of cloth is often dyed with a permanent colour, and artfully stitched to the edge of cloth dyed with a fugitive dye. The frauds committed in the tanning of skins, and in the manufacture of cutlery and jewelry, exceed belief.

The object of all unprincipled modern manufacturers seems to be the sparing of their time and labour as much as possible, and to increase the quantity of the articles they produce, without much regard to their quality. The ingenuity and perseverance of self-interest is proof against prohibitions, and contrives to elude the vigilance of the most active government.

The eager and insatiable thirst for gain, which seems to be a leading characteristic of the times, calls into action every human faculty, and gives an irresistible impulse to the power of invention; and where lucre becomes the reigning principle, the possible sacrifice of even a fellow creature's life is a secondary consideration. In reference to the deterioration of almost all the necessaries and comforts of existence, it may be justly observed, in a civil as well as a religious sense, that "_in the midst of life we are in death_."

FOOTNOTES:

[1] _The Times_, May 18, 1818. The King _v._ Richard Bowman. The defendant was a brewer, living in Wapping-street, Wapping, and was charged with having in his possession a drug called _multum_, 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 200_l._

The King _v._ 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 20_l._ upon the first count, 200_l._ upon the third, and 200_l._ upon the seventh count in the indictment.

The King _v._ 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 30_l._ 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.

REMARKS

ON THE

Effect of different Kinds of Waters

IN THEIR APPLICATION TO

DOMESTIC ECONOMY AND THE ARTS;

AND

METHODS OF ASCERTAINING THEIR PURITY.

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 of _hard_ and _soft_ water 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 are _hard_, 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 is preferable 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 water more or less pure are likewise obvious. Good and pure water softens the fibres of animal and vegetable matters more readily than such as is called _hard_. Every cook knows that dry or ripe pease, and other farinaceous seeds, cannot _readily_ be 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 abundant precipitate, 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. It should 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 not equally 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 very _soft_, and admirably adapted for many culinary purposes, and various processes in different manufactures and the arts.

Fresh-fallen _snow_, 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 melted _ice_ does not contain so much air. _Dew_ has 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 be _hard_, of others _soft_, some _sweet_, others _brackish_, according to 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 termed _hardness_ in 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 occur in 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 thereby becomes 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 metropolis _New 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 suspended than 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 scarcely to 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.