usually employed; it also diminishes the labour of making it, and affords a solid, in place of an inserted, collar; besides which, the lathe is found, by experience, to run a much longer time without requiring to be fresh oiled, than

when the steel collar was used.

Mr. Tyler has also mounted his lathe upon a cast-iron stand, instead of upon the table and nests of drawers, as shown in our plate; holes being made in the frame for the pivots of the treadle and the crank-axle to turn in; the lathe is thus better adapted to the usual run of work than when fitted up in the originally expensive manner.

LXX. On the genuine East Indian Wootz Ore, Iron, and Steel, imported from India by J. M. HEATH, Esq. By the EDITOR.

THE Editor having lately been kindly favoured by Mr. Heath with specimens of this ore, and of articles made of the cast-steel produced from it, and likewise with many particulars concerning these highly interesting subjects, he hastens to communicate them for the benefit of his readers.

The ore is a black magnetic oxide of iron, nearly of the nature of the long celebrated oregrund, or Swedish iron ore, from which our best cast-steel iron is, or properly speaking ought, to be made, only richer. It is a peroxide and protoxide of iron, frequently found in the form of regular octahedrons, and exceedingly rich in iron, and requiring no other addition to the silica generally accompanying it than limestone, to serve as a flux in its reduction to the metallic state.

The natives break the ore into coarse grains, and clean it perfectly, and smelt it in small furnaces, of the height of four feet, somewhat in the nature of our cupola furnaces, and, of course, with charcoal for fuel. They form the iron into bars of an inch broad, and half an inch thick, and cut it across nearly through, into squares fit for putting

into their skittle-shaped melting pots, in order to convert it into cast-steel at once, by putting into the pots with it the wood of the cassia auriculata, or the tree which affords the catechu, employed in medicine as an astringent, and consisting of tannin. The pots; then being perfectly closed at their mouths with clay, are placed in small furnaces, the heat of which is excited by the goat-skin bellows usually employed by the natives; and they are continued therein until the conversion and fusion of the iron into caststeel is at once effected.

The masses of steel possess the well known form of the cakes of wootz formerly imported into this country, and upon which so many experiments have been made by Sir Thomas Frankland, and by others, under the auspices of the late Sir Joseph Banks. It is made from a particular ore only, and not from masses of iron collected indiscriminately all over India, as has been stated by mistake.

Mr. Heath has imported a considerable quantity of the ore into this country, and has had it assayed by that experienced metallurgist, David Mushet, Esq., who has produced beautiful buttons of the reduced iron from it, by the addition of limestone only, and has ascertained the great richness of the ore. He has likewise had it analysed by Mr. Richard Phillips, and had its state of purity from admixture with other metals, and its perfect freedom from the presence of pyrites, phosphorus, arsenic, or the other injurious matters which commonly debase iron ores, correctly ascertained. He has also had iron made from the ore in the large way in this country, and has had it proved in a great variety of ways. Twisted gun-barrels have been made of it by Mr. Fullard, of Clerkenwell, a great test of its goodness; it has also been drawn into the finest wire; he had it rolled into hoop-iron; and also tried by a chain cable maker, when a cylindrical bolt, seven-eighths of an inch thick, was torn asunder by a power equal to seventeen tons and three quarters; he has had thick bars of it bent, until they tore asunder with a fibrous appearance, equal to

that of the very best and justly celebrated Welsh iron; and, in fact, has proved its excellence in a great variety of other ways.

Finally, he has had the iron converted into blister-steel, and that melted into cast-steel, by the principal refiners in this country, and had the steel tilted into bars, rolled into sheets, and made into razors (the goodness of which the Editor can speak to from having used them); and also into pen-knives, fine scissars (the forging the rings in the bows of which latter articles alone sufficiently proves the perfect malleability of the steel), and a great variety of other articles; so that nothing now is wanting but the increased employment of it in this country, as a substitute, produced in one of our own colonies, for the Swedish steel-iron, now, in consequence of the very great demand for it, not to be obtained but at very high prices.

Mr. Heath had the iron also made into blister-steel, by cementation with charcoal in the usual manner, and which proved excellent in that state; as likewise into shear-steel, from which a great variety of articles, such as table-knives, &c. have been made.

Mr. Heath has also had an alloy of wootz and silver made by J. Thompson, Esq., of the London Company's steel works at Chelsea. He put together silver and steel in the proportion of one-four hundredth part of the former metal, but the result of the fusion proved, that it only imbibed one-five hundredth part of the silver, the remainder having separated entirely, and, in fact, had caused a divi sion in the internal parts of the bar drawn out of the ingot; the silver appearing in the different fractures of its native white colour, and in a lamellated form.

The Editor has, at the request of Mr. Turrell, his engraver, put a specimen of Mr. Heath's wootz into his hands, with a view of having gravers' etching-needles, and dry-points, made of it, and thus testing its goodness in the use of those delicate articles. He has also given him a spe

cimen of the above-mentioned alloy of wootz and silver, to prove in a similar manner.

The pen-knife has now been in constant use by the Editor for nearly three months, and its edge still retains its pristine goodness.

LXXI.-On a method of making Cements for Terraces and Floors, and employing melted pitch to render them impermeable to water, and secure from the attacks of Frost. By CASSIMIR PUYMAURIN.

I SHALL not speak of the nature of the different lime cements hitherto known, as they have been fully described by various authors. I shall only observe, that a cement ought to be hard, solid, and impermeable to water. To obtain a hard and solid cement it has been necessary to employ different bodies, which, by their aggregation with lime dissolved in water, speedily absorb the superabundant moisture, and furnish to the particles of lime diffused throughout the cement the carbonic acid necessary for rendering it solid, and transforming it again into calcareous earth.

Vitrified lava, natural and artificial pozzolana, the scoria of furnaces, pounded bricks, bone-ashes, &c. have been the chief bases of all the cements hitherto made, and they have been obtained more or less solid. Cements composed in this manner have been attended with perfect success in the southern parts of Europe, little exposed to rain; they do not absorb the exterior moisture, and the frost has not power to dilate their pores, or to destroy their aggregation.

The cements of Italy, Africa, Spain, and other warm countries, unite all those qualities which can there be desired; but in our rainy countries, exposed also to very severe frosts, cements ought to possess a more essential quality than mere hardness or solidity, that is to say, impermeability. Cements composed of porous bodies cannot

1

possess this quality, they being hard, and having the greatest solidity during summer; but the rains of autumn gradually penetrate to their interior parts, and reduce to powder that mass which a little before had the appearance of the greatest hardness.

The inventors of the most celebrated cements have seen their experiments fail, because they neglected this essential quality of impermeability. The interposition of a fatty body was long ago employed. Pliny and Vitruvius recommend the thick part of oil, and also oil itself; but these bodies employed alone can never answer the intended purpose. Oil forms with the lime of the cement a saponaceous body, soluble in water, and the thick part of oil contains a very large quantity of mucilage, which water dis-" solves and carries off.

To preserve the bottoms of cisterns, and to render them impermeable to water, resinous bodies have been employed, and particularly liquid pitch or tar. I have contrived that my cement should be covered with boiling pitch, as this resinous body penetrates its pores, and renders it impermeable to water. One inconvenience, however, appeared in the use of pitch, which was its property of becoming soft during the heat of summer. This inconvenience I remedied by sprinkling the pitch over with powder of lime; the lime combines with the pitch, and forms upon the cement an exterior stratum of a new cement, resembling the famous cement of the Romans, called maltha.

All the merit of my process consists, therefore, in having been the first to employ a resinous body, capable of penetrating and preserving cements, by filling up their pores, and thus rendering them impermeable to, and consequently insoluble in, water.

I shall here give the method which I generally employ in making my cements, but I must first observe, that there cannot be one general method of composing cements, as limestone and sand are not every where of the same qualities. The reader, therefore, must examine into the nature