possessing only a slight excess of alumine. One is slightly tinged red, and is colored by the oxyde of iron-the other is white, and with a due proportion of felspar and quartz, would no doubt furnish a beautiful porcelain. The felspar - sent by Mr. Woolford, with these clays, is, we think, too much tinged with the oxyde of iron to produce a white porcelain; but from a specimen of granite sent with them, which resembles the graphic granite of New York and the New England States, it is probable that felspar of a suitable quality will be found in the vicinity of the kaolin. The felspar is beautifully white, but the quartz, though found in its usual proportion, has not the regular distribution in layers most generally observed in graphic granite. This is the first specimen of graphite granite, properly so called, which I have seen from Missouri.

The other specimens marked "kaolin," approach more nearly the nature of pipe clay. The excess of alumine in these is too great to render them useful in the manufacture of porcelain, unless as is practised at Sevres, in France, they are submitted to frequent washings to deprive them of their alumine. Compared with a specimen of kaolin in my cabinet, from Limoges, in France, they are somewhat too tenacious-forming what is termed a long paste. In other respects they are nearly identical in physical properties.

The pipe clays sent with these kaolins are of the finest quality, and must, at some future day, prove highly valuable to the manufacturer of queensware, flint or stone ware, and other potteries.

We regard the discovery of these clays as being of immense importance to the manufacturing interests of the State; for, among the earthy minerals, none are more useful in supplying the wants, the convenience, and even the luxuries of life than the clays-essentially composed of two ingredients-silex and alumine in varying proportions. Yours very respectfully,

H. A. PROUT, M. D. Note. We will endeavor to notice more fully these specimens when we shall have made an analysis of them.

CONSUMPTION OF SMOKE.

¡Gentlemen:—In accordance with promise I resume the subject of Smoke-its Consumption and Prevention. In my last I gave you a rough description of C. Y. Williams' Argand Furnace for the prevention of smoke. The principle of its operation is the consumption of the volatile gases emitted from the fresh supplies of coal thrown into the furnace; at which time the gasses are too voluminous to be properly ignited in furnaces of the ordinary kind. The waste of fuel arising from this source, is owing to the want of a proper quantity of oxygen being admitted in the proper place. It is urged by some as an argument against such plans,' that the admission of the atmospheric air tends to cool the furnace, and conse quently prevents the object desired. Such arguments appear futile when we take into consideration the chemical properties of light, heat, &c.; for it is definitely!

ascertained, that to properly consume carbon, it requires ten volumes of oxygen to one of carbon. And when we examine the construction of our furnaces, it will appear evident that they do not admit this proportion of oxygen through the grate-bars when clear of clinkers; hence comes the volume of vitiating smoke from the smoke stacks. It is also demonstrated that oxygen will, (like carbon surrounded by oxygen,) burn brilliantly when surrounded by carbon. Thus you will perceive that by the peculiar construction of the Argand Furnace, the oxygen is admitted through the pierced tubes, (projecting up into the space between the boilers and their foundation,) with 1-4 inch holes, one inch apart; and those jets of oxygen being surrounded by the volumes of carbon as they escape. Brilliant lights are produced from each jet. These jets of flame producing their quantum of heat, the visible effects of this process is likened unto as many trees of fire as there are projecting tubes. Every careful experimental test of this furnace has given all, or more than its inventor claimed for it—a saving of twenty-five per cent!

There are other modes of consuming the volatile gases emitted from coal; amongst which is one known as Ivison's plan, which consists in throwing into the space between the fire and the boiler, a quantity of steam through a fan shaped jet. The theory of this plan is, that the oxygen of the steam combines with the carbon of the smoke, thereby producing combustion. The hydrogen of the steam burns of its own inflammable qualities. This plan answers very well so long as every thing keeps in good order; but the jet pipe is liable to be burnt, which frustrates the design. Now, to make a cheap application of this theory, let all our ash-pils be made so as to hold five or six inches of water, and the grate bars kept clear, so that when the clear, bright rays of the fire strike the water, and the hot ashes fall into it, the increased evaporation which takes place from these causes will make the fires burn more effectually than when the grate-bars are choked up with cinders, and the ash-pit filled with ashes. And do not let our firemen imagine to themselves that by keeping the ash-pit full of hot ashes they are thereby economizing fuel. It is very erroneous.

Another plan for the better combustion of coal, is one known by the title of Jukes' plan, which consists of moving grate-bars-which are in the form of an endless chain, moving on two rollers, at the rate of one inch per minute. One Toller is placed about eighteen inches in front of the fire doors; on this projecting part of the bars the fireman spreads his coal, the bars moving forward under the doors, (which are generally about three and a half inches higher than the bars,) thus leaving an even layer of coal. The bars moving forward bring the coal in contact with the hot fire; then it commences to emit its crude gas. These gases have then to pass over the whole of the burning fire, whereby they become. thoroughly burnt. The bars travel on and drop their ashes at the extremity of the pit; then passing over a gauge they are cleared of any cinders which may have accumulated during the burning of the coal.

If firemen would but study this, they might partially accomplish this object without endless grate-bars. Let the fireman, (when charging,) leave his coal in front of the fire. It will there coke; the fire behind it will burn the carbon in its"passage over it. Then, when properly coked, take his rake, break, and spread it back. Thus he will have a bright, red, and even fire, and the smoke will have but a narrow chance to escape.

M. F. P.

THE BOOT, SHOE AND LEATHER TRADE.

The history of this manufacture is a striking illustration of the boundless ingenuity of man, and of the multifarious wants of civilized life. If we look abroad (says a writer on this subject) on the instruments of husbandry, on the implements of most of the mechanic trades, on the structure of a vast multitude of engines and machines; or if we look at our own clothing-shoes, boots, gloves, caps, &c.; or at the furniture in our houses, the books on our shelves, the harness of our horses, and even the substance of our carriages, what a multitude of instances and forms of this manufacture, wrought out by human ingenuity, meet our eye! What an aptitude has this single material for the relief of our necessities, and the supply of conveniences, in every state and stage of life! Civilized society would suffer immense inconvenience and discomfort from the loss of this one article.

It is a curious, but true reflection, that, though the workers of the article, particularly shoemakers, have generally been ranked low in society, and even among their fellow mechanics, yet from that craft have sprung many of the most distinguished ornaments of our race-scholars, poets, philosophers, patriots, whose fame is immortal.

The aggregate annual amount expended in the boot, shoe, and leather business of this country, nearly reaches the total value of the cotton crop of the United States. As regards the amount of capital and number of hands employed, says the Troy Whig, the shoe business is said to take precedence of any other branch of manufactures carried on in America, producing commodities to the value of $50,000,000 and giving employment to between 100,000 and 200,000 operatives, men and women.

The statistics of productive industry in Massachusetts for 1846 show that there were made, during the year, the following amount of boots and shoes:

All this immense quantity of boots and shoes is made by the hand, no machinery being employed except for the manufacture of lasts and pegs. It is said that vast as the supply is, the market is never over-stocked. The twenty millions of pairs made every year in Massachusetts, are not sufficient for the western market, and we learn, from the Rochester American, that western dealers are compelled to leave their orders ahead, or go without the articles. Many dealers west of the lakes found the market so limited this fall, that they were unable to get their usual supply.

The Canada tariff of 1846 placed a duty on the American articles at so high a rate, that it amounts to prohibition. The Yankees, however, were not to be outdone by its operation. Messrs. Brown & Childs, of Montreal, have opened an extensive manufactory there, and employ some 400 workmen from Massachusetts. They are now supplying the dealers in the upper and lower provinces.

The Mercantile Times furnishes a statement of the same manufacture in England; from which it appears that the total amount of leather tanned, tawed, dressed, and curried, is estimated at 50,000,000 lbs., which, at 1s. 8d. per lb., is £4,166,000 as the value of the leather only. Supposing the value of the leather to amount to one-third the value of the articles produced from it, that would show a result of about twelve millions and a half.

The number of hands employed in all the various branches, from the tanner to the finisher of the finest manufacture of leather, is estimated at 275,000; while the wages paid amount to about £7,000,000 sterling, or nearly $34,000,000. Scotland is not included in this estimate.

STAFFORD'S PATENT PROCESS OF PRESERVING BREADSTUFFS. Several notices of this invention have appeared in the eastern papers, all of them speaking highly of the invention. We have deferred any extended notice of it, until its merits should be to some extent tested. Messrs. E W. Andrews & Co. of the Empire mills in this town, have had one of the machines in operation upon corn meal, for about one year. About 1500 barrels of this meal, manufactured last spring, was shipped to Europe. It not only performed the voyage of the lakes, canals and rivers of our own country, but after remaining during some of the hottest months in store, it was sold in Liverpool, for from 3s. to 3s. 6d. sterling, per barrel more than the current quotations of the market for corn meal. The enhanced price is understood to have been realized in consequence of the superiority of this process for expelling the moisture, over all others; meal prepared by this process being devoid of any other taste or smell than that which pertains to the natural meal. Heretofore it has been deemed necessary to destroy the germinating principle of grain, to enable it to withstand the vicissitudes of climate, and hence the parched, ill-flavored meal that is usually sent abroad, being divested of much of its nutrition, is rendered entirely unfit for the use of man. Mr. Stafford's theory is, that without the presence of moisture nothing in nature can change. Upon this theory is his machine made to operate. It is simplicity itself. A cylinder armed with flanches on the exterior, is made to revolve in a troughthe inclinations of the cylinder and trough moves the substance to be dried gradually to the opposite side from which it was received. The interior of the cylinder is heated by steam. By this simple process Mr. Stafford is enabled to obtain all that is requisite for preserving grain, flour, meal, &c., for an indefinite time. The heat is uniform, the motion of the article drying is constant, and the ventilation perfect.

So far as we are able to judge of this invention from the tests already made of its utility, we are inclined to regard it of very great importance, particularly to the grain-growing regions of the west. The amount saved to the Government would be large if they would supply the ships of the navy with flour and meal sufficient for a long voyage, with a perfect assurance that they would remain good for any length of time. So of whale ships, &c. Mr. Stafford richly deserves not only the large pecuniary benefit which is already made sure to him, but also the grat-itude of the world.

The Cleveland Herald says: Flour from Ohio wheat, dried by Mr. Stafford's process, loses 8 per cent. of its weight. This fact has been recently tested at Elyria. When, therefore, dried flour is exported the miller will save transportation upon 16 pounds of water to each barrel, the consumer paying at the same rate for 196 pounds of dried flour that he would for 212 pounds of undried. The consumer, then, has the certainty of purchasing and having flour always sweet and fresh, instead of running the risk of buying flour which is stale, musty, or sour.-[Elyria (Ohio) Courier.