Part 18

_Red Lead_, or _Minium_, is a mineral substance of red colour, used for painting, and made, by a tedious and troublesome process, from massicot. For this purpose the massicot is ground to a fine powder, put into a furnace, and constantly stirred, whilst the flame of the burning coals plays against its surface for about forty─eight hours, when it is converted into a red powder, which is the article under consideration. It is subsequently passed through very fine iron sieves. The use of red lead as a pigment is well known; but as it is liable to turn black, vermilion is generally preferred to it. It is sometimes employed in medicine as an external application for abating inflammations, for cleansing and healing ulcers, and the like; and is used in the manufacture of glass.

_Litharge_ is another kind of oxide of lead. This is prepared by exposing calcined lead to a brisk fire for a certain length of time. The substance, on cooling, concretes into a flaky matter. Litharge is used by potters for the glazing of earthenware, but vessels that are glazed with it are thereby rendered unwholesome. It is also employed, in the composition of the finer kinds of glass, for the purpose, not only of giving them greater transparency, but also of rendering them capable of sustaining sudden changes from heat to cold, and of giving to them a susceptibility of being cut without breaking. It, however, adds considerably to the weight of the glass.

_Litharge Plaster_, or _Diachylon Plaster_, as it is more frequently called, is prepared by boiling two pints of olive oil with one pint of litharge, adding water, and constantly stirring the mixture till they are duly incorporated. This plaster is applied in excoriations of the skin, slight wounds, and other sores.

_Sugar of Lead_ is a preparation either from the metal itself, or from white lead and distilled vinegar. It is usually observed in the form of small slender crystals, which have a glossy appearance like satin. This substance is employed, in considerable quantity, by dyers and calico printers; and is the basis of a liquid frequently used in medicine, called _Goulard_, or _Goulard’s Extract_. Although in itself a most virulent poison, it is often used by unprincipled dealers for correcting the rancidity of oil of almonds and olive oil; and a similar pernicious fraud is practised by dissolving a portion of it in wines which are becoming acid, in order to correct their acidity. These frauds, however, are easily detected by preparations or tests, which are sold by chemists for that purpose. Perhaps the best and simplest test is Harrowgate water: a little of this poured into the suspected compound will discover the presence of lead by giving to the fluid a dark brown or blackish tinge.

The following is a pleasing experiment. Dissolve an ounce of sugar of lead in about a quart of water; filter the solution through a piece of blotting paper, and put it into a glass decanter, suspending in it a piece of zinc by a brass wire. A decomposition will take place; the lead will be set at liberty, and will attach itself to the zinc, forming there a sort of metallic tree.

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It has been stated that silver is usually a component part of lead ore. To disengage this, where the quantity is sufficient to repay the expense, the lead, after it has been smelted, is subjected to the action of what is called a refining furnace. A continued blast of fresh air is thrown upon its surface by means of large bellows, while the lead is kept in a state as intensely hot as possible. This by degrees converts the lead into a yellow scaly oxide or dross. The oxide, thus formed, is driven off from the melted metal as it rises, and the silver is left alone at the bottom, in a metallic state. After the operation is complete, the oxide is fused with charcoal, and again reduced to metallic lead.

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We must not omit to mention that, in some of the mines of Derbyshire, there is a singular variety of lead ore called _slickenside_. This is a kind of galena, which presents, to the eye, a smooth and bright surface, appearing as if it were plated. Sometimes it forms the sides of cavities; and it has the extraordinary property, when merely pierced with the miner’s tool, of rending with great violence, and exploding with a crackling noise. Some miners, fearless of danger, venture to scratch it with their tools; and, on coming again to the spot, they often find that, during their absence, the slickenside has exploded, and fallen off in considerable quantity. Sometimes, however, they suffer for their imprudence. Mr. Mawe, in his account of the Mineralogy of Derbyshire, says, that he has seen a man come out of a mine cut violently, as if he had been stabbed about the neck and in other parts of the body, in consequence of the explosion of slickenside which he had pierced. The cause of this extraordinary phenomenon has not been explained.

240. _NICKEL, when pure, is a fine white metal, somewhat resembling silver in appearance, but it is attracted by the magnet, and has itself the property of attracting iron._

_It is ductile and malleable, difficult of fusion, and about nine times heavier than water. This metal is always mixed with arsenic (242) and iron._

Nickel is found in Cornwall, and in some other counties of England; in Germany, Sweden, France, Spain, and several parts of Asia. The Chinese employ it in making white copper; and, in conjunction with copper and zinc, they manufacture it into various kinds of children’s toys. Nickel gives a certain degree of whiteness to iron. It is used, with advantage, by some of the Birmingham manufacturers, in combination with that metal, and by others in combination with brass. If it were possible to discover an easy method of working nickel, there can be little doubt but it would be found a very valuable metal for surgical instruments, for compass needles, and other articles, as it is not, like iron, liable to rust. When nickel is freely suspended, it points to the north and south, in precisely the same manner as the common magnetic needle.

Oxide of nickel is used for giving colours to enamels and porcelain. In different mixtures it produces brown, red, and grass─green tints.

241. _ZINC, or SPELTER, as it is sometimes called, is a bluish white metal formed in thin plates adhering together. It has a very perceptible taste, is about seven times heavier than water, rather harder than silver; and possesses but a small degree of malleability and ductility, except under certain circumstances._

_This metal is never found in a pure state; and the principal ores from which it is procured are known by the names of_ Calamine _and_ Blende. _Of these the former is an oxide (21) of zinc combined with carbonic acid (26), and the latter is a combination of zinc with sulphuric acid (24)._

The ores of zinc are very abundant in many countries. We are informed that nearly the whole of Flintshire in North Wales abounds with calamine; and that, so entirely ignorant were the inhabitants of its use, as, till after the middle of the eighteenth century, to have even mended their roads with it. These roads, however, have since been turned up in many places, and the materials have been converted to more valuable purposes. Derbyshire affords a great quantity of the ores of zinc, particularly calamine. This is found at various depths, generally in beds of yellow, or reddish brown clay, and usually near some vein of lead ore.

The mode of extracting zinc from its ore is by distillation. The process adopted, in some parts of Saxony, is equally simple and ingenious. An inclined stone is placed near the anterior part of a furnace, in which the ore of lead containing zinc is fused. A great part of the zinc condenses upon this stone, and flows, in drops or globules, into a quantity of charcoal placed at the bottom to receive it. These globules are afterwards again melted, to run the metal into a mass.

When exposed to the air, the surface of zinc is soon tarnished, but it scarcely undergoes any other change. It has a certain degree of ductility. When heated a little above 218° of Fahrenheit, it is malleable; and, when annealed, may be passed through rollers, and formed into thin sheets or leaves. Although, previously to being thus heated, it is brittle; on now cooling, it continues soft, flexible, and ductile. The inconvenience arising from the brittleness of the zinc being removed, this metal is applicable to many useful purposes. It may even be drawn into wire, but the tenacity of this is not great: a piece of zinc wire, one tenth of an inch in diameter, will sustain only a weight of twenty─six pounds without breaking. It has been proposed to substitute zinc in the place of tin for the lining of copper vessels; but it has not hitherto been ascertained whether this can be done with effect, and without injury. Prizes have of late been offered, to a considerable extent, in France, for the ascertainment of this fact. In China, zinc is employed as a current coin of the country; and for this purpose it is used in the utmost purity. The Chinese also, as well as the artists of our own country, employ it to a great extent in various alloys. It is used in the manufacture of _brass_, _pinchbeck_ or _prince’s metal_, and _bronze_, all of which consist of this metal in combination with different proportions of copper (230). _Tutenag_ is a well known white metal, made principally of zinc, and used for forming candlesticks and other articles. When tutenag is well manufactured, it is of good colour, and not more disposed to tarnish than silver. Zinc is one of the metals employed to form the galvanic or voltaic apparatus; and its filings are mixed with gunpowder, to produce those brilliant stars and spangles which are seen in the best kinds of artificial fire─works. Preparations of zinc are occasionally used in medicine. If a thin plate of zinc be applied to the upper surface of the tongue, and a shilling to the lower surface, and both metals, after a little while, be brought into contact, a very peculiar taste will, at that instant, be perceived. The same sensation will be perceived, though in a weaker degree, if the silver be placed at the top and the zinc at the bottom.

If a silver probe be introduced high up one of the nostrils, and be brought into contact with a piece of zinc placed on the tongue, a sensation not unlike that of a strong flash of light will be produced in the corresponding eye. A similar perception will result, both at the moment of contact and that of separation, if one of the metals be applied as high as possible between the gums and upper lip, and the other in a similar situation with the under lip, or even under the tongue.

A white oxide (21) prepared from zinc, was, some years ago, proposed as a substitute for white lead in house painting. This oxide is not dangerous in its application; and does not become yellow when mixed with oil. But these advantages are counterbalanced by some defects, which have hitherto caused it to be rejected. It is lighter than white lead: does not cover the surface so equally, nor so well; and is of considerably higher price.

CALAMINE.—The principal use of calamine is in the manufacture of brass (230); and the mines of Derbyshire, and of Limbourg in the Netherlands, supply with this mineral nearly all the brass works in Europe. After the calamine is dug out of ground, it is reduced to pieces not in general larger than a nut. It is then roasted for five or six hours, in what is called a reverberating furnace. The large pieces are separated, and the small ones are passed through a sieve. It is washed; and, when dry, is ground in a mill. In this state it is sold. The principal demand for it is at Birmingham, for the different brass founderies in that town.

The use of calamine in the composition of brass was known at a very early period. It is mentioned by Aristotle, who also makes a distinction between the compound resulting from the mixture of copper and calamine or brass, and that resulting from the mixture of copper and tin or bronze.

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ORDER II.—BRITTLE METALS,

OR SUCH AS ARE NOT CAPABLE OF BEING FLATTENED OR ELONGATED BY THE HAMMER WITHOUT TEARING OR BREAKING.

242. ARSENIC, _in a metallic state, has a bluish white colour, and considerable brilliancy; it is remarkably brittle, is the softest of all known metals, and is somewhat more than eight times heavier than water._

_It is found nearly pure, and in considerable abundance, in different parts of Germany; usually occurring in masses of various shapes, and in combination with a small portion of iron, gold, or silver._

_The arsenic sold in the shops, and too well known for its poisonous qualities, is an oxide (21) of this metal artificially prepared._

In some mines on the Continent arsenic is very abundant, and is found extremely injurious to the workmen. Being very volatile, its fumes affect and destroy the lungs, and occasion death in a short time to many of them. One of its ores, _arsenical pyrites_, is found abundantly in Cornwall and Devonshire, accompanying ores of copper and tin; and, in combination with other metals, it occurs, in a greater or less proportion, in almost all mines.

Arsenic is occasionally used in the arts. It is employed in various metallic combinations where a white colour is required, and, particularly, for the whitening or bleaching of copper, which is thereby also rendered capable of taking a fine polish; hence its use in many of the compositions for the mirrors of reflecting telescopes, and for other optical instruments. The manufacturers of glass frequently employ the oxides of arsenic in the fabrication of that article. Arsenic is used in the processes of dyeing and calico printing; and for the imparting of different artificial shades and colours to furs. It is also used in the manufacture of small shot, from its rendering the lead more brittle, and better capable of being formed into grains, than it would be without such admixture.

The arsenic of commerce is prepared to a great extent in Bohemia and Saxony, by roasting cobalt ores for the manufacture of zaffre (247). _White arsenic_ is made, by mixing the common oxide with potash, and submitting it to a certain degree of heat, in vessels adapted to the purpose; the arsenic, rising in fumes, is separated, leaving the sulphur behind, united to the potash. This process is called sublimation.

Of all substances with which we are acquainted this is perhaps the most deadly. If only a few grains of it be taken into the stomach, it proves fatal; and it has frequently proved the more injurious from its deceitful appearance, in which it somewhat resembles salt or white sugar. Carelessly left in places open to the access of children, arsenic has not unfrequently been mistaken by them for sugar, and has been attended with the most dreadful consequences. If thrown on heated coals, however, it is immediately known, by the smell of garlic, and the white fumes which it gives out. The best remedy for this poison is said to be a few scruples of liver of sulphur (sulphuret of potash), dissolved in half a pint or a pint of water, and administered a little at a time, as the patient can bear it.

Notwithstanding its deleterious qualities, arsenic is occasionally used in medicine, though in extremely small doses; and it has, in particular, been found efficacious in many cases of intermittent fever.

It is employed as a poison for rats and mice; and, diluted with water, it attracts and poisons flies, whence it is sometimes called by the French, _poudre a mouches_. There cannot, however, be too great caution used either in the preparation, or in the application, of this fatal poison.

243. _YELLOW ORPIMENT is a mineral substance of lemon colour, which consists of arsenic in combination with sulphur; and in the proportion of about fifty─seven parts of the former and forty─three of the latter._

_It is about thrice as heavy as water; and is found both in a massive and crystallized state; but the crystals are so confused that their figures cannot easily be determined._

The orpiment of commerce is an artificial production, and is chiefly imported from different parts of the Levant. The Turks, and other Orientals, use it in the depilatories which serve to render bald the top of the head. A very beautiful, but fugitive pigment, called _King’s yellow_, is prepared from this mineral; and other preparations of orpiment are occasionally used by painters, and also by dyers and calico printers. The whole of these, however, are extremely poisonous.

Orpiment is found in a natural state, along with copper and other ores, in Natolia, Servia, Hungary, Turkey, and some other countries.

244. _REALGAR, or RED ORPIMENT, is a mineral substance of red or orange colour, which consists of arsenic in combination with sulphur; and in the proportion of seventy─five parts of the former, and twenty─five of the latter._

_It is somewhat more than three times as heavy as water; and occurs sometimes in a crystallized, and sometimes in a massive or disseminated state._

This production, which, by ignorant persons, is not unfrequently mistaken for red lead, is in considerable request by painters, dyers, and calico printers. In China it is manufactured into small pagodas and other ornaments. And the Chinese form it into medical cups, and use lemon juice which has stood for some hours in them, as a cathartic. Realgar is poisonous, but by no means so much so as arsenic (242).

It is found in Sicily, Hungary, and various parts of Germany: and is very common in several districts of China.

245. _ANTIMONY is a compact metallic substance of brilliant and slightly bluish white colour, destitute of ductility, and about seven times heavier than water._

_Its texture is laminated, the plates crossing each other in almost every different direction. It is as hard as silver, and so brittle that it may easily be reduced to powder, in a mortar._

In the state of the Connecticut, North America, it is said that antimony, in a pure metallic form, is found in such abundance that, in some places, large masses of it may be seen lying on the surface of the ground. The principal supply of antimony in Europe is from an ore which is found in Hungary and Norway, called _sulphuret of antimony_. The process of bringing it into a state for use is very simple. The mineral is put into pots, each of which has a hole in the bottom, and which is placed on another pot bedded in the earth. The upper pots, which are filled with the mineral, are heated. As soon as the antimony is fused it flows into the lower pots, while the substances with which it was combined remain in the upper ones. The antimony fixes, and forms cakes of the shape of the pots which receive it. In this state the metal presents, in its fracture, a surface thick─set, with long needle─shaped crystals, which, lying by the side of each other, compose, as it were, the whole of the mass. It is afterwards re─melted and cast into cakes for sale.

This metal, in a pure state, or alloyed only with a very small portion of silver and iron, is found in veins of mountains in some parts of France and Sweden, occurring in massive and kidney─shaped lumps of white colour.

The only mine of antimony in Britain, which is of any importance, is at Glendinning in Dumfries─shire. It was discovered in 1760, in searching for lead ore, but was not regularly worked till 1763. In the first five years about a hundred tons’ weight of antimony were obtained from it. This at 84_l._ per ton, produced the sum of 8400_l._ The undertaking was afterwards relinquished, but, as the price of antimony is now at least thrice what it then was, it is supposed that this work, if resumed, might prove an advantageous speculation. The vein of ore is only from eight inches to a foot and a half in thickness.

Antimony was known to the ancients. The earliest account we have of it is in the Sacred Writings. The passage in the Second Book of Kings,[4] which states that, on the approach of Jehu to the city of Jezreel, “Jezebel painted her face,” implies, in the original, that she stained her eyes and eyebrows with antimony, for the purpose of making them look black and large, a custom which, at that period, was prevalent in several of the Eastern countries. Antimony was likewise considered by the ancients a remedy against inflammations of the eyes.

This metal is the basis of many of the officinal preparations which are now in use; and it was the basis of many others which were formerly used, but are now discontinued. No mineral substance has so much attracted the attention, or so much divided the opinion of physicians, as antimony. One party extolled it as an infallible specific for almost every disease; whilst another described it as a virulent poison, which ought to be expunged from the list of medicines. It was on this metal that the alchemists of the middle ages principally founded their hope of discovering the philosopher’s stone; and, by a kind of good fortune, of which we can cite but few examples, it has happened that, in pursuing a chimera, they hit upon a succession of important realities. To the unremitted perseverance with which they tormented this metal, if we may so express it, the art of healing has been most essentially indebted.

Footnote 4:

Ch. ix. v. 30. See also Ezek. Ch. xxiii. v. 40.

The first rational account of the properties of antimony was given, about the end of the seventeenth century, by a French chemist, whose name was Lemeri. Its great importance in medicine will be seen by an enumeration of some of the most valuable preparations of it which are still in use.

_Antimonial Wine_ is prepared from antimony, in conjunction with white Lisbon wine. It is employed as an emetic; but, if mixed with milk, this quality is said to be completely destroyed, and it becomes narcotic.

_Emetic Tartar_, which is much more employed in this country than all the other antimonial preparations put together, is formed from antimony mixed with its own weight of tartar, and a certain proportion of water, and afterwards boiled, filtered, and suffered to crystallize.

_Butter of Antimony_ is obtained from a combination of antimony with corrosive sublimate. It is denominated by chemists muriat of antimony, and is usually a thick fatty mass of greyish white colour.

_Glass of Antimony_ is a vitreous substance of reddish brown colour, which is occasionally used in medicine, but more frequently in colouring the imitations of yellow diamond, Oriental, Brazil, and Saxon topaz, hyacinth, emerald, and beryl.

_James’s Powder_, or _Antimonial Powder_, is a well─known medicine, composed of phosphat of lime and antimony.

An alloy consisting of sixteen parts of lead and one part of antimony constitutes the metal of which _printers’ types_ are formed. This alloy does not differ from lead except in being considerably harder and more tenacious. The plates on which music is engraved are formed of a mixture of tin and antimony; and the oxides of antimony are used for the colouring of glass.

246. _BISMUTH is a reddish white semi─metal, harder than silver, and composed of broad brilliant plates adhering together._

_It is nearly ten times heavier than water, and is so brittle as readily to break under the hammer. None of the semi─metals are so easy to be fused as this; it melts even in the flame of a wax candle, and long before it becomes red hot, and has the singular property of expanding as it cools._

The ores of bismuth chiefly occur in Sweden, Norway, Germany, France, and England. This metal appears to have been known to the ancients. It was confounded by them with tin; and, even in our own manufactories, it is known to the workmen by the name of _tin─glass_.