secret on me, but in vain. He asked me for a piece of gold, and opening his doublet, showed me five pieces of that precious metal, which he wore on a green ribbon, and which very much excelled mine in flexibility and colour, each being the size of a small trencher. I now earnestly again craved a crumb of the stone, and at last, out of his philosophic commiseration, he gave me a morsel as large as a rape seed; but, I said, "This scanty portion will scarcely transmute four grains of lead." "Then," said he, deliver it me back;" which I did, in hopes of receiving a greater parcel; but he, cutting off half with his nail, said, "Even this is sufficient for thee." "Sir," said I, with a dejected countenance, what means this?" And he said, "Even that will transmute half an ounce of lead." So I gave him great thanks, and said I would try it, and reveal it to no one. He then took his leave, and said he would call again the next morning at nine. When he returned, I confessed that I had scraped off a bit with my nail, when the substance was in my hand, which I had projected in lead, but it caused no transmutation; for the whole flew away in fumes. "Friend," said he, "Thou art more, dexterous in committing theft than in applying medicine. Hadst thou wrapped up thy stolen prey in yellow wax it would have transmuted the lead into gold." I then asked if the philosophic work cost much, or required long time, for philosophers say that nine or ten months are required for it. He answered, "Their writings are only to be understood by the adepts, without whom no student can prepare this mystery. Fling not away, therefore, thy money and goods in hunting out this art, for thou never shall find it." To which I replied, "As thy master showed it thee, so mayest thou perchance discover something thereof to me, who know the rudiments; and, therefore, it may be easier to add to a foundation than begin anew." "In

this act," said he, "it is quite otherwise; for unless thou knowest the thing from head to heel, thou canst not break open the glassy seal of Hermes. But enough: to-morrow, at the ninth hour, I will show thee the manner of projection." But 'Elias never came again; so my wife, who was curious in the art whereof the worthy man had discoursed, teased me to make the experiment with the little spark of bounty the artist had left me; so I melted half an ounce of lead, upon which my wife put the said medicine. It hissed and bubbled, and in a quarter of an hour the mass of lead was transmuted into fine gold, at which we were exceedingly amazed. I took it to the goldsmith, who judged it most excellent, and willingly offered me fifty florins for each ounce.Brand's Manual of Chemistry.

SUBSTITUTE FOR COCHINEAL.

IN the steppes of the Ukraine there grows in great quantities a plant, named polygonum minus, which is gathered at the end of July; it is torn up by the roots, which contain a species of maggot, or insect, of an oval shape, and which hardens by being exposed to the air.

They are put into a certain quantity of water, with the addition of a little alum; and this water becomes, after a short time, of a most beautiful scarlet colour. The Cossack women, who sell it to the Russian merchants, dye their thread with it, and likewise use it to paint themselves. The Polish Jews and the Armenians sell a great deal of it to the Turks, who use it to dye their silks, to make morocco leather, and to dye the tails and manes of their horses; they even dye their own hair, their beards, and their nails with it. They call this maggot coceus polonicus. According to an experiment made at Moscow, a pound of these maggots, which costs a rouble, produces as much colour as half a pound of cochineal,

TO PROCURE OXYGEN GAS, AND BURN STEEL. OXYGEN gas, called also vital air, is one of the constituent parts of the atmosphere; and though, if breathed entirely pure, it causes a hurried and laborious respiration, it is nevertheless essential to life. Atmospheric air supports life from the oxygen it contains. Oxygen also supports combustion; with some few exceptions, its presence is necessary to combustion, and, in general, other substances only aid combustion from the quantity of oxygen they contain. It is also one of the constituent parts of water, and has been named, though perhaps erroneously, from a supposition that it was the acidifying principle. It gives sourness to many compounds, but not to all; it is a colourless elastic fluid, like common air, though somewhat heavier than it, and has neither smell nor taste; it is one of the substances the young chemist is earliest made acquainted with, and with which, from its very great importance, he continues most familiar; it may be produced in several ways. We shall give a description of two.

To obtain it in the greatest purity, put two or three drachms of chlorate of potash, also called oxymuriate of potash, into a glass retort, A, capable of holding about two ounces of water, and apply to it the heat of a spirit lamp, B. The first portions of air which arise must be rejected on account of their being mixed with the atmospheric air of the vessel; but when the salt is completely melted, oxygen gas rises in abundance,

Or this gas may be obtained by putting black oxide of manganese coarsely powdered into the retort, A; pour upon it a sufficient quantity of sulphuric acid to form a liquid paste, and then apply the heat of the lamp, and oxygen gas rises abundantly.

To collect this gas, take a common earthenware bason, C, and place across it a board of four or five inches wide, and about three quarters of an inch thick, having a slit wide enough to pass the bottle, D, through, terminating in a hole, so that the bottle will stand upright. The bason is to be filled with water, and the bottle full of water is to be placed inverted in the hole. This is done by immersing the bottle in the bason, and then placing it upright, without allowing the mouth of the bottle to be ever out of the water. When the bottle is thus placed, and the atmospheric air has been expelled from the retort, carry its mouth through the water into the mouth of the bottle; the oxygen gas rises in bubbles to the top of the bottle and gradually displaces the water. The bottle then appears empty, but is, in fact, full of oxygen gas. If it is required to fill more bottles than one, a regular pneumatic apparatus is necessary, which will be hereafter described. In the mean time, having one bottle full, let us proceed to burn steel wire in it, one of the most brilliant experiments of chemistry, and which has been displayed to numerous bodies of admiring spectators.

Take a bit of steel wire, from nine to twelve inches in length, and

about 1-20th of an inch in diameter; coil it tightly round a bit of stick, half an inch in diameter, and then withdraw the stick: this will bend the wire in a spiral form. Fix one end of it into a cork, which fits the mouth of the jar or bottle in which the oxygen gas is contained, so that it may hang down when introduced into the bottle, and be kept firm by the cork, as in the figure, E, at the other end of the wire attach a little charcoal, or thread dipped in sulphur; light the thread or the charcoal, and plunge the wire quickly into the bottle; it will instantly take fire, and throw out in all directions a number of brilliant sparks. The burning will appear in a dark room dazling like the sun, and be, for those who have never witnessed such an experiment, inconceivably splendid. If the wire be moved with a sudden jerk during the burning, so as to throw a melted globule against the side of the glass, it will melt its way through, or lodge itself in the substance of the glass. If instead of the bottle we use a bell-glass, completely open at one end, having a mouth to which a cork is adapted at the other, and which is filled in the manner above described, but when full is removed, by a common saucer or porcelain vessel being placed beneath the open end, then the globules of the metal falling through the water on to the saucer will fuse the glazing, and fix themselves so firmly that they cannot be separated without scraping off the glazing. It is hence necessary, when performing the experiment on a small scale, to cover the bottom of the glass with sand to prevent the red hot globules from cracking it.

CHEMISTRY AS A SCIENCE.

Art. I.

INTRODUCTION.

WE shall not be far wrong, we believe, in supposing that some of our readers may be totally unacquainted with the science of Chemistry, and that we shall meet their views by putting an outline

of this science within their reach, in a cheap and periodical form. Without pretending, however, to draw up a whole system of Chemistry, though we shall be far from merely copying what others may have written on the subject, we shall under the present title present our readers, in a series of articles, with a short and familiar view of Chemistry as a science. While the more advanced students will find in other parts of the work information suited to their wants and their taste, the papers under the present title are intended for those persons who are beginning the study.

Every body must have observed that most of the substances around us are in a perpetual state of change, and that many of these substances act upon and destroy one another. Thus iron rusts, and is, at length, unless protected from the air, quite wasted away and destroyed; and even the hardest wood moulds and decays, so that in a few years it falls into dust and disappears from our view. Thus also wood is instantly destroyed by a few drops of vitriol; and the weakest acid corrodes iron. Now, it is a settled principle, confirmed by many observations, that substances which, like the iron and the wood, change their characteristics and appearance, are not utterly lost or annihilated: the fact is, that they are converted into some other things. The great agents in producing these changes are water and air.* What we drink, and what we breathe, therefore, while they are to us so apparently harm

* We may here observe, for the satisfaction of scientific readers, that we do not include fire or caloric among these active agents, because, as must be known to them, there are among the best informed chemists differences of opinion, whether caloric be a separate substance, or only a property of all matter. If the the latter, it would be as improper to informer, we are wrong in omitting it; if clude it, as to include wind, which all philosophers know to be merely a movement-synonymous with a property-of

air.

less, so really beneficial, and even so necessary to our health and our existence, are also the causes of those numerous changes which are constantly going on before our eyes, and which are called decay and destruction. That the same principles which warm every being into life also bring on decay and destruction, is a fact which we shall often have occasion to advert to and illustrate: we only briefly allude to it now in mentioning those numerous changes which are going on in every thing around. The whole surface of the globe, in fact, the whole universe is perpetually and periodically changing; but all these changes take place without the annihilation of any portion of matter.

Some of these changes are accompanied by a perceptible motion; thus the waters of the ocean daily rise and fall: others are not so accompanied; thus the state of iron and wood is gradually altered, and nothing but the familiarity of the alterations keeps us from wondering at their cause. It is the object of mechanical philosophy to explain those alterations which are accompanied by perceptible motion; and it is the object of Chemistry, by ascertaining the peculiar properties of all bodies, to explain those which are not. This is what gives dignity and interest to the science. As long as Chemistry was a mere art, confined to producing a few results, of use only to a few practical Chemists, it was of no more general interest, however useful, than the art of house-building or shoe-making; but now, in addition to its utility as an art, it endeavours to explain most of the alterations, unaccompanied by perceptible motion, which take place in all the substances of the globe.

It has been already stated that there is no annihilation; there must be therefore some things which are changed or altered. Formerly it was supposed that all these alterations were effected in four elementary substances, viz. fire, earth, water, and air; and so powerful has been the influence of

this supposition, which originated many centuries ago with the ancient Egyptians or Greeks, that it now forms a part of the popular belief throughout Europe. The four elements are frequently talked of, and were not long ago taught as the bases of some sciences. It is the business of the Chemist to ascertain, if he can, what are the actual elementary bodies of which every one of the different objects of the globe are composed. Some are submitted to the action of fire, others to that of powerful solvents; some are exposed to the action of water, and others are submitted to clectricity; and by all these, and various other means, he endeavours to discover the different simple or elementary substances which undergo all these changes. When, by all the means which he can invent, he cannot change or decompose one substance into two others, it is called a simple substance, or an element. In the language of Chemistry, therefore, the term elements signifies those bodies which the CHEMIST has not been able by his art to decompose. Unfortunately for the chemistry of the ancient world, and the theory of four elements, they have all been decomposed by the art of modern chemists. We shall hereafter point out their composition; to do it now would draw us aside from our principal subject. In place of them, modern Chemists are at present acquainted with, according to some writers, fiftyseven, and according to others, fiftytwo different substances, which they have not yet been able to change or decompose. It is, however, remarkable, that few or none of these substances are ever found in a natural state; and they are nearly all of them the produce of the chemist's art. All the substances and things of the globe, whether animals, minerals, vegetables, or airs, (gases), which have hitherto been subjected to chemical examination, and there are perhaps very few unexamined, are found to consist of one or several of these elementary bodies. They are like

the letters of the alphabet, with which we put together all our words, and of them is this whole world of wonders composed. Nay, there is good reason to believe, as the science of Chemistry, which is yet in its infancy, advances to perfection, that this list of elementary substances will be decreased. To decompose them is one great object of the scientific Chemist's ambition; and we trust many of our readers, when they have acquired a knowledge of the science, as it now exists, will turn their attention to its improvement.

There are two modes in which a knowledge of these elementary substances may be conveyed to the student of chemistry. The first is, to show him, by going through an analysis of every known substance, of what elements it consists; the other is simply to bring these elements before him in succession. The former would, in fact, be making him do what others have done for him; the other is applying to his immediate instruction the discoveries and knowledge of others. We prefer the latter as more simple, and shall, in our next Article, proceed to describe the substances which, never having been yet decomposed, are considered as elementary or simple substances.

TESTS FOR ARSENIC. The use which is sometimes made of this substance to destroy life, makes a knowledge of the means of detecting its presence of great practical utility. The substance sold under the name of arsenic in the shops, is called arsenious acid, or white oxide of arsenic, by chemists the former name being, at present, more in use than the latter. The term arsenic is applied by chemists to a metallic substance obtained from arsenious acid, and which they consider to be a distinct metal. With its properties we have now nothing to do, as this paper is to be devoted to the virulent poison, called arsenic in the shops, and arsenious acid by the chemists.

It is a white brittle substance,

has a sharp acrid taste, which at last leaves an impression of sweetness and a very peculiar smell, somewhat like that of garlic. When the arsenious acid is thrown on red hot coals, it evaporates in white fumes, and this peculiar smell is then very perceptible. It is rather more than three and a half times as heavy as water; and though it may be suspended in this fluid by agitation, it soon subsides if the agitation is put a stop to. Boiling water will dissolve a quantity about equal in weight to the fourteenth part of the water. Cold water only dissolves about one tenth part as much as boiling water. Other authorities say it is soluble in thirteen times its weight of boiling, and eighty times its weight of cold water. Water in which arsenious acid has been dissolved, reddens litmus paper, as well as the most sensible of the blue vegetable colours, but it turns the syrup of violets green. If lime water be added in sufficient quantity to the solution of arsenious acid, a fine white precipitate, which is arsenite of lime, is perceptible. Sulphuretted hydrogen gas and hydrosulphuretted water precipitate a golden yellow sulphuret of arsenic: and by this test a portion of arsenious acid in water, not greater than a hundred thousandth part of the whole, may be detected. If this yellow sulphuret be dried on a filter, and heated in a glass tube with a bit of caustic potash, it will, in a few minutes, be decomposed: sulphuret of potash will remain at the bottom, and metallic arsenic, of a bright steel lustre, which sublimes, will be found coating the sides of the tube. Nitrate of silver is decomposed by arsenious acid, and an arsenite of silver, of a very peculiar yellow colour, is precipitated. To prevent this precipitate being dissolved by nitric acid, which is very often present, a small quantity of ammonia is added; and even this, if too much is added, is also likely to re-dissolve the silver precipitate.

To ascertain if arsenious acid has been administered, the first