and strongly upon the hard parts than on the rest of the surface.*

Formerly, no man in Great Britain knew how to temper a sword in such a way that it would bend for the point to touch the heel and spring back again uninjured, except one Andrew Ferrara, who resided in the Highlands of Scotland. The demand which this man had for his swords was so great that he employed workmen to forge them, and spent all his own time in tempering them; and found it necessary, even in the day-time, to work in a dark cellar, that he might be better able to observe the progress of the heat, and that the darkness of his workshop might favour him in the nicety of the operation. Had this ingenious artist thought of a bath of oil, he might have heated this by means of a furnace underneath it, and by the use of a thermometer, to the exact point which he found necessary; though it is inconvenient to have to employ a thermometer for every distinct operation. Or, if he had been in possession of a proper bath of fusible metal, he would have attained the necessary certainty in his process, and need not have immured himself in a subterranean apart

ment.

The swords which were formerly in the highest repute, were made at Damascus in Syria. The method by which these were made, has long been lost; or perhaps it was never thoroughly known to Europeans; but it is supposed that they were formed by alternate layers of extremely thin plates of iron and steel bound together with iron-wire, and then firmly cemented together by welding. These weapons never broke, even in the hardest conflict, and yet they retained so powerful an edge, that the armour made like net-work with scales of iron, or with small iron rings, called coats of mail, was instantly divided under their force.

This manufactory at Damascus had formerly the greatest reputation throughout Europe and through a great part of Asia; but in the latter end of the fourteenth, or at the beginning of the fifteenth century, Timour Bec, usually called Tamerlane, on his conquest of Syria,t carried away all the best workers in steel from Damascus to Persia; and we know so little of Persia, that it may be difficult now to ascertain whether this peculiar manufactory is still carried on in that country or not.

* Nicholson's Quarto Journal, vol. iv. p. 131.

↑ Gibbon's History of the Decline and Fall of the Roman Empire, vol. xii. pages 21 and 45.

A writer in Nicholson's Journal, who had the opportunity of examining a real Damascus blade, which had cost the possessor twelve guineas at Constantinople, has thus described. it: "It had (says he) a dull grey or blueish appearance, was scarcely harder than common steel from the forge, was not easily bended, and when bended had no spring to recover its figure. Its back was smooth, as were also two narrow sloped surfaces which formed its edge under an angle of about 40 degrees; but its flat sides were every where covered with minute waving lines in masses in all directions, not crossing each other, and, for the most part running in the direction of its length. The lines were in general as fine as harpsichord wire, not extremely well defined nor continued; and their distinction from each other was effected by no perceptible indentation of the surface, but rather by the succession of parts differing in the degree of polish or brightness."

"I was informed," says the writer of the memoir, "that if any part of this blade were made smooth by grinding or whetting, the wavy appearance, called the water, could be again produced by means of lemon juice; and that its excellencies were, that it could be depended upon not to break; and that it would cut deeper into a soft substance, such as a pack of wool, or into flesh, than any other kind of sword blade."

66

"I infer therefore," adds the writer, "that the Damascus steel is in fact a mechanical mixture of steel and iron; that it is incapable of any considerable degree of hardness, and consequently is in no danger of breaking from its brittleness; that its tenacity is ensured not only from the admixture of iron, but likewise from the facility with which its soundness may be ascertained throughout, by the same process which exhibits the water or fibrous appearance; and, lastly, that the edge of a weapon formed of this material must be rough, on account of the different resistance which the two substances afford to the grindstone, in consequence of which it will operate as a saw, and more readily cut through yielding substances than such cutting tools as are formed of a more uniform substance."*

The conjectures of this writer respecting the methods by which these blades were manufactured at Damascus, and the account of the experiments which he himself undertook for the purpose of enabling him to imitate them, are extremely

"Nicholson's Quarto Journal, vol. i. pages 468–471.

interesting and instructive, so much so that I have no hesitation in recommending the whole paper to the perusal of all those who are curious in the manufacture of edge tools.

I would not have it understood that I wish to lay any claim to the merit of the discovery of metallic baths for the tempering of edge tools, because I know of two or three individuals who, for some particular articles, have for several years adopted this expedient; but I have reason to believe that the few cutlers who have been in the habit of tempering in a fluid bath, have always employed a thermometer; whereas the object of my experiments is to furnish a list of baths, either of which may be used with certainty, without employ. ing that instrument. Moreover, as the practice is very much confined, and few workmen, comparatively, have any idea that it would be possible to render such a method available, I was desirous of explaining its principles, and of furnishing a scale by which the manufacturer might acquire the means of tempering any instrument whatever, in such a manner as will render it entirely suitable to the purpose for which it is intended.

Another kind of edge tool remains to be described, which is made of cast-iron and afterwards converted into steel. The method of conducting this process was discovered by Mr S. Lucas of Sheffield, and he has obtained a patent for the invention.

The invention by Mr Lucas, of converting edge tools made of cast-iron into good steel, appears to be an important improvement. It consists in stratifying the cast articles, in cylindrical metallic vessels, with native oxide of iron pulverized, or sand containing oxide of iron, and then submitting the whole to a regular heat in a furnace built for the purpose. It is not necessary that the oxide employed should be a native oxide, any artificial oxide being equally effective; that kind which can be had cheapest is therefore generally preferred. The operation may be thus explained :

The cast-iron, of which this cutlery is made, is brittle in the first instance, like other cast-iron, in consequence of the carbon contained in it; but the great heat which it undergoes, aided by the pulverized oxide, separates the carbon: this uniting with the oxygen of the ground oxide of iron, is dissipated in the state either of carbonic oxide or carbonic acid gas, and the goods are then converted into a state very similar to that of good cast-steel cutlery.

To prevent misconception, it may be necessary to state,

that cast-iron which contains a large proportion of carbon is less brittle than that which is combined with a smaller quantity. It can also be filed and cut with a cold chisel, while the latter, although it may be more readily broken, effectually resists the action both of the chisel and the file. In conformity with these facts, small machinery made of common cast-iron may be softened merely by cementation with a carbonaceous substance, thereby augmenting its dose of carbon, and rendering it capable of being smoothed by the file.

I understand that the best pig-iron is always chosen for making the various articles of cutlery, while the poorest iron ore, if free from sulphur, may be pulverized and stratified with them to afford oxygen.

After several years' experience, Mr Thomas Lucas has been enabled to bring this process to such a state of perfection, that his cast cutlery will bear a polish* equally brilliant with the best cast-steel goods, as I can testify from my own observation; and will al-o take as fine an edge, so that some of the best judges of cutlery cannot distinguish the difference. When, however, the cast cutlery wares, which have been thus annealed, are submitted to the usual processes of hardening and tempering, they are apt to be more brittle than those edge tools which are made in the usual way with the best steel.

It has also been found that by varying the process, small pig-iron castings can be converted into good malleable iron: in consequence of this the Patentee now makes a great variety of small iron utensils by casting, which were formerly made only on the anvil of the blacksmith; and when he has converted the metal to the quality of soft malleable iron, these articles are found to be equally fit for a great variety of purposes, and can be afforded at a much lower rate than similar goods which have been modelled by hand, as heretofore. He has become so complete a master of this business, that he can convert cast-iron goods either into the state of wrought iron or steel at pleasure.

* Directions by Messrs. Stodart and Hume for preserving polished steel instruments from rust by means of an ethereal solution of gold, are given in Nicholson's Journal, vol. xi. p. 215. A paper by Mr Stodart on covering steel with platinum is printed in the same volume, p. 282. See also a paper on the same subject by Guyton Morveau in the Annales de Chimie, tome 77, p. 297.

ART. XXXVII.-On the Anhydrous Sulphurous Acid, and on its application to the Liquefaction of some other Elastic Fluids. By M. Bussy, of the School of Pharmacy. [Brewster's Jour.]

THIS very interesting paper was read at the Society of Pharmacy in Paris, on the 15th March 1824, and is published in the Journal de Pharmacie for April 1824. Independently of the value of this Memoir, it may be considered as confirming the experiments of Mr Hutton of Edinburgh, who succeeded in the year 1810, in freezing alcohol at the specific gravity of .798. As Mr Hutton did not publish his method, in consequence of his using it in his extensive manufactory of artificial salts, some doubt was entertained respecting his experiments; but those who had opportunities of knowing the talents and scientific resources of that gentleman, never doubted the reality of his results. These results, too, are described with a minuteness of detail which no sagacity could have anticipated; and we doubt not that the process of congelation discovered by M. Bussy, when brought to higher perfection, will either completely establish or overthrow the detailed results given by Mr Hutton.

M. Bussy's Memoir is so interesting, that we shall gratify our readers by a translation of the whole of it.

"Having been led, by researches in which I was engaged, to suppose that anhydrous sulphurous acid could be obtained liquid by a simple diminution of temperature, I made some experiments which confirmed this opinion. I had at first believed that a considerable reduction of temperature would be necessary, and I consequently collected the gas in very powerful frigorific mixtures; but I soon found that a mixture of two parts of ice with one of muriate of soda was sufficient to liquify completely the gas without losing the smallest quantity.

"The apparatus which I employed consisted of a matrass, in which I put equal parts of mercury and sulphuric acid. This mixture served to produce the gas, which first passes into a vessel surrounded with melting ice, in order to condense the greater part of the water which it might carry along with it. It afterwards passes into a long tube, filled with fragments of fused muriate of lime, and it finally passed into a small flask, surrounded with the cooling mixture, where it condenses itself into a liquid with the pressure of the atmosphere. "When obtained in this manner, the liquid sulphurous acid