also much used by chymists for procuring oxygen gas, which it gives out in great abundance, by the application of a red heat. What is the nature of tungsten?

Tungsten is a heavy metal, procured from a mineral found in Sweden, and from an ore called wolfram, found in our county of Cornwall, Germany, &c. but its properties are not much known, neither is it brought into any use here*. The same may be said of molybdenumt, uraniumt, titanium, tellurium, chromiums, columbium, and tantalium. It will therefore be proper to defer the consideration of these metals till their properties are further investigated.

Having gone through the greater part of this chapter on metals, endeavour to recapitulate the general properties of this class of bodies?

The metals are simple substances**, distinguishable from all other bodies by their lustre, by their great specific gravity, by their perfect opacity, and by their superior power of conducting electricity.

What are the obvious advantages which we derive from these bodies?

The metals are the great agents by which we are enabled to explore the bowels of the earth, and to examine the recesses of Nature; their uses are so multiplied, that they are become of the greatest importance in every occupation of life. They are the instruments of all our improvements, of civilization itself, and

Tungsten has been used in France for making vegetable lakes. Its oxide is insoluble in either of the three mineral acids, which is not the case with the oxide of any other metal. Though tungsten has been recommended as a proper basis for colours, it shows in some instances a strange fuga. cious disposition. Mr. Hume left a piece of zinc for some time in some of the triple açıdulous solution, generally called tungstic acid, and obtained a most brilliant blue solution: this was placed over the gentle heat of a lamp to evaporate, and soon lost all its colour. Phii, Mag. vol. xix. 29.

+ Molybdenum has been employed, I believe, in some processes of dyeing in Germany. As it may be procured in great plenty, it will probably some time hence come into general use here.

mica.

Uranium, combined with carbonic acid, is found in the common green

§ A beautiful green colour may be obtained from this metal useful for painting in oil or distemper, or for applying to porcelain. The metal was called chromium, because of its property of imparting colour to a variety of other bodies.

Columbium was discovered in a mineral sent from Massachusetts, in North America. See Mr. Hatchett's paper on this metal in the Philosophi cal Transactions for 18oz.

Tantalium was found in an ore from Swedish Lapland. Its characteristic is, that it is insoluble in all the acids.

**The ancient chymists supposed the metals were compound bod es. They were probably d t this by observing the pulverulent nature of the metallic oxides. Their undecompounded nature was first suspected by Mayo.

are even subservient in the progress of the human mind towards perfection*.

You can doubtless offer some reasons why one metal possesses such opposite and specific differences from another?

This variety is not to be attributed to chance, but must certainly be the effect of consummate wisdom and contrivance. These metals differ so much from each other in their degrees of hardness, lustre, colour, elasticity, fusibility, weight, malleability, ductility, and tenacity, that nature seems to have had in view all the possible necessities of man, to suit every purpose his ingenuity can invent or his wants require.

By what means are these bodies rendered so important to us?

We not only receive this great variety from the hand of Nature, but these metals are rendered infinitely valuable by various other properties + they possess. By their combustibility, their solubility in fluids, their combinations with phosphorus, sulphurs, and carbon, and by their union with each other, whereby com

The metals are seldom afforded by Nature otherwise than in a state of great impurity. It is to the use of the reasoning faculty that we owe the possession of any of them in a state fit for use. If we consider for a moment what would be the situation of the world if society were deprived of this class of bodies, we should then have some idea of the obligations we owe to the sciences of metallurgy and chymistry.

"Şerene philosophy,

Effusive source of evidence and truth!

Without thee, what were unenlighten'd man?
A savage roaming through the woods and wilds,
Rough clad, devoid of every finer aṛt

And elegance of life."

THOMSON.

The best information respecting the analysis of metallic ores may be had from Klaproth's Essays, to which I refer the reader.

† Much information on the nature of the metals may be collected from Mr. Hatchett's valuable paper on gold, in the Philosophical Transactions for 1803.

Some of the metals are so combustible that they will burn before they acquire a heat sufficient to fuse them. This is the case with iron and zinc. A thin shaving of zinc, as we before noticed, will burn if held in the flame of a candle, without melting. The combustion of iron in oxygen gas is an interesting and beautiful experiment. See an account of the method of managing it in the chapter on Combustion.

All the metals except platina and gold will unite with sulphur by fusion. But the natural sulphurets contain more sulphur than the artificial ones; they must therefore have been formed by Nature by different means to those we employ in forming these compounds.

Several of the metals have a very strong affinity for each other, as may be shown by experiment. Mercury will dissolve lead, bismuth, zinc, and other metals. If a piece of lead and a piece of bismuth, each alloyed with mercury, be melted together, they form when cold a solid metallic mass

pounds or alloys are formed extremely useful in a variety of arts, manufactures, and other requisites of life.

By what other means does Nature render these bodies subservient to our wants, and capable of ministering to our comfort and gratification? Nature has furnished us with acids, whereby the most refractory metals may be dissolved and purified, and rendered fit for a variety of purposes to which they could not otherwise be applied; and by combining them with oxygen we can invest them with new properties, and are enabled to employ them to promote the progress of the fine arts, by imitating the masterpieces of creation, in the production of artificial salt, spars, and gems, of every colour and of every shadet.

How does oxygen produce these changes in metals?

Different metals acquire different colours by their union with oxygen, and the same metal attains a different hue, according to the portion of oxygen combined with it; so that this wonderful substance seems destined not only to render us the most important services, but to embellish the works of creation, by the beautiful tints which it imparts to almost all subjects, whether of the animal, vegetable, or mineral kingdom.

You seem to think that the changes which metals undergo by their absorption of oxygen are the most surprising phenomena of nature:can you recollect some other properties of oxygen, to serve as a comparison, and to elucidate its importance ?

but from their affinity for mercury they have acquired so much fusibility that they will melt by the heat of boiling water. See note, page 221.

*The alchymists were in search of an universal solvent of all metals; but, as Mr. Davy has remarked, if such a solvent really existed, nothing would be so much dreaded by modern chymists. It would prevent the analysis of every mineral into which it entered, and would be like the fabled water of the Styx, which petrified every thing it touched. How different are the views of the scientific chymist to those of the ancient adepts, who concealed their knowledge with the greatest care, and appear to have had no other view but to surprise a gaping multitude!

+ If phosphoric acid be united with silex by fusion, artificial precious stones may be prepared with the compound, which may be coloured to imitate any particular kind, by one or other of the metallic oxides.

The oxide of iron is an eminent example of this change of colour. No less than seven distinct colours, besides a great variety of shades, are observed in minerals containing iron; and to the iron in most cases is the colour to be ascribed.

White in the somnite.

Black in the obsidian.

Green in the euclase.

Blue in the lazulite.

Red in the garnet and ruby.

Yellow in the topaz.

Brown in the tourmaline.

When I consider, in addition to its multiform effects upon metals*, that no animal can exist; no acid can be formed; no kind of combustion whatever can take place; nor even the most insignificant vegetable perform its proper functions, without the agency of this most astonishing substance, I cannot but exclaim-We want no further proofs to demonstrate, that the organization of the world has been effected by superlative wisdom and consummate goodness-attributes belonging to HIM only, who has thus supplied our wants, and administered to our comforts, and even to our luxuries. Other instances might be enumerated in which oxygen is indispensably necessary: its importance is, however, too eminently conspicuous to be overlooked in the formation of water; every atom of which, whether we consider the ocean, lakes, rivers, and fountains, that pervade every corner of this material world, or the vapours of its atmosphere, all is made up of three-fourths of this single simple substance,

OXYGEN.

*It is no unusual thing for the votaries of chymistry to call it a fascinating science. That it is the most useful of all sciences cannot be denied; nor can there be the least doubt that it has a strong tendency to enchant those who devote their attention to it. It serves as a powerful stimulus to youth, by Occupying their time so satisfactorily to themselves, and rendering all low and unworthy pursuits truly detestable. But amidst the great variety of subjects which this science embraces, the changes which the metals undergo by their absorption of oxygen are perhaps more eminently calculated than any other of its departments, to give a relish for chymical pursuits, and to engage the young mind in the unremitted examination of the works of creation.

"The philosophic youth,

TO NATURE's voice attends, from month to month,
And day to day, through the revolving year;
Admiring, sees her in her every shape;
Feels all her sweet emotions at his heart;

While TRUTH, divinely breaking on his mind,
Elates his being, and unfolds his powers."

THOMSON

CHA

CHAPTER XI.

OF OXIDES.

WHAT is an oxide?

Any one or more of the simple substances, when united to a less quantity of oxygen than what is necessary to form an acid, is called an oxide.

What substances are capable of forming oxides?

The mineral, the animal, and the vegetable kingdoms, all furnish matters which are convertible into oxides by their union with oxygen*.

What minerals are convertible into oxides?

The metals are all capable of forming oxidest: so is sulphur, which is a peculiar substance, often found in combination with metals.

In what do metals become united to oxygen?

way

The oxides appear to range themselves into two classes. There are oxides which are permanently such, so long as they retain the oxygen which enters into their formation; and there are others which seem to possess only a kind of intermediate state between combustibles and acids, being convertible into acids by a further portion of oxygen. This will appear as we proceed.

+ According to the old theory, metals were supposed to be oxidized by the loss of phlogiston; and when these oxides were reduced to a metallie state, it was imagined that they recovered their phlogiston from the carbonaceous matter employed in their reduction. Those persons who have not been in the habit of reading the works of the older chymists may understand them by attending to the following particulars: In most cases, all that is necessary is to substitute the word oxygen for phlogiston, with a slight inversion of the language. For the effects which they attributed to the combination of phlogiston appear to be due to the extrication of oxygen; and what they supposed to be owing to the loss of phlogiston were really occasioned by the absorption of oxygen.