No. 4.

Smelting Iron.

57

holes, at least those of an inch or more ||important art, or in the various improvements across, are also covered in the same manner. which it is likely to lead to in other operaThe general method of laying down ve- tions. The following is a very brief outline neers is very simple, although to do this well of the manner in which the heated air is and correctly, requires, as every thing else || applied in some of the iron works where does, practice, attention, and patience. The this method of working the ore has been under side of the veneer, if previously introduced. smooth, must be scored by means of a toothing plane; but if cut by a circular saw, it generally acquires a sufficient tooth by that operation. The surface to be veneered is covered over with strong glue, and before it chills or gelatinizes, the veneer, previously prepared and cut to the shape required, is laid down upon it, care being taken in doing so, to enclose as little air as possible. When it has been pressed down to its proper bearing in every part, the compound piece is enclosed between two hot boards, secured at the edges by thumb screws, or, which is still better, is put into a press between two hot plates, where it remains till perfectly dry.

vent at the farther extremity. They may be considered, therefore, as placed on the floor of a long and reverberatory furnace, about six feet high, and nearly of the same breadth, being at the same time protected by fire bricks where they might be injured by the direct flame of the furnaces.

The air is blown by cylinder bellows in the usual manner, but before entering the smelting furnace it passes through pipes of cast iron heated to redness, which are altogether about thirty feet in length, and three feet in diameter. They are usually made in three or four pieces, joined together by apertures considerably less than three feet in diameter, and placed horizontally, or in whatever manner the local arrangements about the furnace may render most convenient. A brick arch is then thrown round the pipes, leaving a free space of about eight inches and upwards between it and them, and two or more furnaces constructed so as to heat the pipes in the archway, the flues The next process is to give a smooth sur-playing into it, and terminating in a common face to the veneer, which is effected by first filling up any holes by plugs of the same kind of wood cut to fit them, or by making a paste of fine saw dust and glue, and pressing it into the holes by hand, and then by the successive use of small planes, scrapers, files, glass-paper, Dutch rushes, and flish skin. Lastly, a varnish is added, which has the effect of bringing up the color and lustre of the wood, and protecting it from the action of the air. If the color of the wood is itself unexceptionable, the varnish should be as colorless as possible; but if a little mellowness or warmth is required, a varnish colored accordingly must be applied. The so called, French varnish, has, within the last few years almost entirely superseded the oil varnishes, as being more quickly applied, possessing more lustre and hardness, being less liable to be injured by any common liquid spilled upon it, and not requiring to be renewed or refreshed except at long intervals. It is made by dissolving lac in spirits of wine, and then shaking it up with olive oil to the consistence of an emulsion, in which state it must be used. It is fixed on the surface of the wood by means of a linen rubber, applied with a circular or spiral motion. Varley in Trans. Lond. Society Arts.

The iron ore is smelted according to this plan with a little more than half the coal necessary when the furnaces are worked with air in the usual manner; the small coal which is sold at an inferior price is found quite sufficient for heating the pipes.

It has also been ascertained, that there is no difficulty in smelting the iron ore with common coal instead of coke, and in some furnaces at present in use, no coke whatever is employed, so that it is probable the trouble and expense attending its preparation will be unnecessary. It is likewise in contemplation to endeavor to reduce the iron ore at once in the furnace, without any previous calcination, and the proprietors of some of the iron works seem to entertain little doubt that they will be successful in the attempt.

The great effect produced by the heated air in these furnaces must be attributed to the circumstance that, according to this plan, a higher temperature can be more easily excited and maintained, than when the blast is supplied with air at the ordinary temperature of the atmosphere. And the great saving of fuel we would presume, does not arise from a greater QUANTITY of heat being evolved from a given quantity of coke, or coal, in the one case than in the other, but from the greater INTENSITY of temperature that prevails when the heated air is employed, insuring the more steady and certain

58

Use of Alumina with Pigments.

VOL. I.

action of the charcoal on the calcined iron- || happened to see, so far as we could judge stone, less or none being exhausted without from bare inspection, appeared excellent. an adequate return, i. e. consumed at an inferior temperature, without affecting the ore

Edinburgh New Philos. Journal.

designed for the Pallet.

BY A. A. HAYES, ROXBURY LABORATORY.

in contact with it. It is possible, however, On the use of Alumina with Pigments that the absolute quantity of heat evolved may differ according to the temperature at which an inflammable substance is consumed, though no precise experiments have been made to determine this.

ments with oil, the artist is often perplexed In preparing his paints, by levigating pigby the diversities which they exhibit after If we consider the quantity of air required this operation. Some pigments present a for the combustion of common inflammable chemical combination with the oil, while matter, we shall be better able to appreciate others can be suspended in it only by conthe important effects which must arise from siderable labor, and soon separate when left the use of heated air. Let us suppose that at rest. These differences can be rendered coke alone is used in the smelting furnace, of trifling importance, by employing such a and that carbonic oxide is the sole product substance as will retain those compounds of the combustion in that part of the furnace which possess no attraction for the oil, in a where the blast takes effect upon the fuel, state of uniform suspension, and whose acthen, even according to this calculation, tion will be in some respects analagous to every six parts by weight of charcoal re- that of the gum used in inks and water quire no less than thirty-six of atmospheric colors. The property which the hydrate, or air for their combustion, this quantity con- carbonate, of alumina possesses, of mixing taining only eight parts of oxygen. Ac- freely with oil so as to form a transparent, cordingly, though the air may be so thin and consistent and almost colorless compound, attenuated that we are apt to overlook its admirably fits it for this purpose. At the cooling influence, every portion of combus-request of Mr. Rembrandt Peale, I prepared tible matter mixes with six times its weight some pigments by mixing them with alumina of cold air, (air at natural temperatures,) all while moist. When ground with oil, he of which must be heated to a certain extent found them to possess all the most valuable at the expense of the fuel already in a state properties of the best colors. The tendency of combustion, before it can give out any to separate from the oil, and the disagreeable heat by its action on the inflammable matter property, which some colors possess, of beof the coal. If, again, carbonic acid be the coming more fluid when an attempt to preproduct of the combustion when the heat is serve them is made by immersing the pallet more powerful, twice as much air, (seventy-in water, disappear, after they have been two parts,) will be necessary for every six of charcoal, or each portion will require twelve times its weight of air. The first effect of the introduction of this large quantity of cold air, must be to diminish the actual temperature of the furnace, however much it may add to it immediately afterwards as it is consumed. If, then, the air be heated before it passes to the furnace, its For printing from blocks, as in the manutemperature must be higher than when air facture of ornamental floor-cloths, it is deis supplied in the usual manner, just in pro-sirable to increase the fluidity of the paint, portion to the degree of heat previously communicated to it.

ground with a small portion of alumina. The artist has it in his power, thus, to increase or diminish the fluidity of his paints, and to render them uniform. Some pigments become valuable as glazing colors, as the Prussiate of copper, (Hatchette's Brown.) Vermilion and Naples Yellow, acquire new properties.

so as to prevent the dropping of small threadlike parts on the work, without causing it to spread. This may be accomplished, by adding a small quantity of whiting to the pigload his blocks with paint, and consequently ment while grinding; the artisan can then give a thick coating to the print.

The high temperature of the furnace not only enables the iron ore to be melted with less fuel than would otherwise be necessary but by effecting a complete separation of the scoriæ from the melted iron, may contribute also to produce a purer and more perfect pig iron; as it is possible, however, that under these circumstances the iron may receive a larger impregnation of the bases of the earths which are decomposed in a small quantity during this operation, the quality of the product demands the most careful examination. The specimens weit the better.

Silliman's Journal.

There are some things which every one ought to know; there are other things which need only to be known by particular persons: and there is a knowledge, concerning which it may be said that the less any man has of

Colors used in Painting.

|| Venetian red, and Spanish brown, are natural productions, or native ochres.

Terra de Sienna, is also a native ochre, imported from Italy, of a yellow color originally, but when moderately calcined, becomes an orange red, though not very bright. Carmine is prepared from cochineal, by means of alum, and other chemical agents.

Lake is procured from cochineal, brazil wood, or scarlet rags, by boiling the color out by means of pearlash, and afterwards precipitating it on some earthy body, as chalk, cuttle-fish bone, &c.

Rose pink is prepared in nearly the same manner, only the base being principally chalk, and the colouring obtained from Brazil or Campeachy wood.

Red ochre is a native earth, principally from Oxfordshire; but what is commonly used is calcined, and made red from the common yellow ochre.

Ultramarine is prepared from lapis lazuli, a beautiful blue stone, found in various parts of the world; it is calcined, and undergoes a very tedious process.

11

VOL. I.

The French appear to have effected a great improvement in candles by separating the crystalizable portion of tallow, the stearine, from its other constituents, and rejecting the latter in the composition of their bougies. But stearine itself is a compound of stearic acid and glycerine, and it is the former only which is wanted in the preparation of the most perfect bougies.

To accomplish this most perfect depuration, the stearine is converted into soap, with lime, and this soap is then decomposed by dilute sulphuric acid, forming an insoluble precipitate of sulphate of lime, and leaving the crystallizable stearic acid free.

The saponification of the stearine with lime, is aided by a high temperature, (140° cent. 284 Far.) which produces a corresVerditer is obtained by adding chalk or ponding pressure on the liquid, and by suitawhiting to a solution of copper in aqua fortis.ble agitation. The stearic acid, when sepaCommon verditer is made from the sulphate rated, is thoroughly washed by hot water of copper, or blue-stone. Verditer has been and steam, and then set aside to crystallize sometimes called Sander's blue, from igno- in tinned vessels. rance of the meaning of the_term cendres bleus, or blue ashes, which the French call it. Indigo is extracted from a plant, which is cultivated for the purpose in the East Indies, &c. Dissolved in sulphuric acid, and diluted, it forms Scott's Liquid Blue, so much used for coloring silks and other articles.

Prussian Blue. Iron is the basis of this fine pigment, called, from the place where it was first discovered, Berlin or Prussian blue. This color was accidentally discovered about the beginning of the last century, by a chemist of Berlin, who having successively thrown upon the ground several liquors from his laboratory, was much surprised to see it suddenly stained with a beautiful blue color. Recollecting what liquors he had thrown out, and observing the same effects from a similar mixture, he afterwards prepared it for the use of the painters. The process of manufacturing Prussian blue, is by calcining a quantity of vegetable alkali or potash, with twice its weight of dried bullock's blood, until it be reduced to a perfect coal. This coal is boiled in water, the lixivium decanted, and poured into a solution of one part of sulphate of iron, (green copperas) to six of alum, the lixivium and the solution both hot. The mixture will then acquire a very pale blue color, and deposit as pale a precipitate. On adding more and more of a fresh solution of copperas, the color becomes deeper and deeper. In order to separate the

The cakes thus obtained are broken up, put into sacks, and subjected to the gradual action of a hydraulic press. The greater part of the oleic acid is thus forced out, with a variable portion of the solid acid which it carries with it, depending on the tempera

ture.

The material thus obtained is still more completely purged by a cold pressure in other hydraulic presses, not less powerful, but arranged horizontally. This leaves the solid matter of a splendid pearly white, exempt from odor, but not yet sufficiently purified. It is melted again in water, sharpened with sulphuric acid, washed, and cast into moulds, when it becomes a crystalline mass, and is fit for the preparation of stearine candles.

The strong tendency to crystallization presented a formidable difficulty in the moulding of the candles. In the earlier manufactory of the improved candles this difficulty was overcome only by adding twenty-five to thirty-three per cent. of wax, to the purified stearic acid. This added greatly to the cost.

An attempt was made at improvement by adding about a thousandth part of arsenious acid, in powder, to the stearic acid. This pretty effectually cut the crystals, (as the workmen termed it,) but the process was objectionable, diffusing a disagreeable odor in apartments where many of the lights were burning.

No. 4.

Education of Mechanics.

61

The great argument made use of, and which is thought to contain so much of truth, is, the old #nock-down argument—'want of time.' This is an error. Every mechanical profession may be better obtained and more thoroughly understood by spending a portion of the time in a well directed, scientific course of study than otherwise. Besides, even admitting that it could not, it is not true that there is not time. Witness the many hours and days occupied in things of less moment-aye, worse than unoccupied. Let us look back, and review the past-what says the long line of years which some of us have trodden? Do we not discover that much, very much might have been accomplished? We cannot recall the past, but we may better appropriate the present and expected future. This we can do, and we

M. de Milly now employs a more simple process, exempt from all reproach, and which requires only five hundredth parts of wax. It consists in disturbing the crystallization by a rapid transition from the liquid to the solid state, effected by dipping the moulds momentarily in water, of about the temperature of congelation, of the purified material, and then pouring in the melted substance at a temperature but little higher than the melting point. This ingenious management secures to this fine improvement all the success that could be hoped for. The manufacture has become greatly extended; the|| wholesale price has been lowered from 2 fr. 25 c. to 1 fr. 75 c. and the retail price from 2 fr. 50 c. to 2 francs the metrical pound, while at the same time the quality of the article is much improved. A steam generator is used in De Milly's factory for heating,||can tell to our children and apprentices of and in most of the mechanical operations, the mistakes we have made, and show them and about eighty people, men, women and by our example that we feel it. children are employed in it.-Bull. d'Encour. Mars, 1836.

Without this mental training, and desire for investigation, we shall constantly be under the necessity of borrowing our opinions from others-receiving their dogmas as truth, without the ability to judge of its character,

rendering ourselves the machines of the cunning-the dupes of knaves and the slaves of aspirants!

We deny, now and forever, that the pursuits of the laboring man disqualifies him from becoming well informed and intelligent. It is alone his business.

From the Mechanic and Farmer. Education of Mechanics. There never was a time when it became more important for mechanics to take hold in earnest to advance themselves in education-to study earnestly, deeply and perseveringly-than the present. There is a disposition to turn all good learning to account --to apply it to the common uses and purposes of life. It is a subject of vast im- Look at what mechanics have done-and portance that mechanics, farmers and work- say, may not the same be done again? Wilingmen should be thoroughly impressed, liam Shakspeare was bred a wool-comberthat they should enter into the spirit of the Brinley was a mill-wright-Richard Arktimes, and manfully strive with a bold and wright was a barber-I. Watts was an indetermined zeal to become masters in science.strument maker-Benj. Franklin a printerIt has too long been thought sufficient for a Robert Sherman a shoemaker-Nathl. Green mechanic to read, write and spell, with a blacksmith-John Chandler a blacksmith enough knowledge of arithmetic to add up-and we might quote a long list of worthies accounts. Let us away with such mean who have risen by the force of their own ideas, and set out with a determination to merits-by attending to their own education, know something more, to be constantly toil- to fill important offices, and to bless and ening in some intellectual pursuit. A knowledge lighten, and cheer mankind. of Geometry, Chemistry and Mechanics, and There is a luminous halo surrounding their connection with the arts, is almost, if these benefactors of their race which is not altogether indispensable. These philo-pointing us, to arise-shake off the apathy sophic studies teach men to think, and when with which we are clothed, and improve the they begin to think rationally and philo- faculties which heaven has bestowed. sophically they will then proceed on, limited We would not say, that we shall see a only by health or the means in their power. sudden and instantaneous ripening of earth We learn much of these sciences prac-into heaven. But we do say that we may tically, by observing the operations of others, all be better prepared for the duties of life, who perhaps have learned it in the same and that it is important for us all

way. This is not sufficient. We should study to know the cause-the why and the wherefore. This can only be done by seizing upon the treasures which are so liberally

"In mutual, well beseeming ranks
To march one way."

The reason why many people know com

scattered over the field of science, and which ||paratively nothing, is because they never opens in abundance before us.

can bear to be told any thing.