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should say; and again it passes to hot irons to remain for hours, perhaps days. When it comes thence, for dressing combs, it is quilled, or that part to be cut into teeth made thinner than the rest. Next the teeth themselves are cut roughly, in a very ingenious manner, which we believe they call twinning. Formerly the interstices of the teeth were cut out by a thin saw, and of course the strip of horn made but one comb, the fragments being lost. Now, the piece makes two combs, the sides of the strip, which are left ridged in the quilling process, furnishing the two backs, and the teeth being between, which are formed by fastening the strip in a carriage, which is moved forward till it comes under a chisel, that with the precision of clock-work cuts out the two combs, the teeth of one lying between those of the other.

When the teeth have been cut the two combs are pulled apart and again replaced, and then go into cold irons to press and straighten. That being done, they go through several other processes. One man shapes the points of the teeth, another the sides of the teeth, and a third smooths the edges of the back— all being done with machines; and afterwards they are polished and packed up, and sent to markets as distant from this and from each other as the points whence the horns are received, though they should be collected from the four quarters of the globe and the islands of the seas.

MANUFACTURE OF HUNGARY LEATHER.

This valuable kind of leather, says the Shoe and Leather Reporter, is chiefly used, at present, for harness and similar purposes, though we think it probable that the same method of preparation might be advantageously employed for the production of leather adapted to more extensive purposes. This kind of leather can be prepared for market in three weeks in summer, and in about double that time in winter. This rapid tanning process consists in impregnating hides with alum, common salt, and animal oil. The leather may be made at all seasons of the year, since the injurious effects of temperature can easily be counteracted. This kind of leather differs much from that which is tanned and curried; as the latter is well known to consist, not of the gelatine of which the hide is composed, joined with the tannin in mechanical union, but of a third substance as distinct from both as water or air are distinct from the gases of which they are respectively composed. The Hungarian leather, on the contrary, consists of the origi nal fibrous tissue of the hides dried, contracted, and slightly changed in nature, but not converted into true leather. Another difference between the Hungarian tanned skins and ordinary leather consists in the fact that, on an average, the former loses one-half of their original weight. The methods of preparation of hides and skins for this Hungarian process are very similar to those usually employed in our tanneries. After unhairing, the hides are dressed with a solution of alum and salt, by which putrefaction is prevented and the hides are rendered stronger and more durable, while the salt mixed with the alum by keeping the fibers moist, renders the leather more supple. Six pounds of alum, three-and-ahalf pounds of salt, and about eight gallons of water are required for a hide weighing eighty pounds.

After being twice dressed with alum and well tramped upon by the bare feet of the workmen continually walking backwards and forwards over them, the skins are dried, and are then, by another process of tramping or rolling, prepared for tallowing. This process is conducted in a close room, containing a boiler about three-quarters full of tallow, which is heated until it melts, when the

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leather, which has been previously warmed, is thoroughly saturated—above three pounds being required for each hide. Calf-skins, however, though prepared in the same way, require less of the tanning materials-the average consumption for a dozen large skins being fourteen pounds of alum, seven pounds of salt, and thirteen pounds of tallow. After being thoroughly saturated with tallow, the leather is flamed, or exposed to heat, and is then thoroughly dried in the open air.

From Senegal Hungary is said to have borrowed this method in the fourteenth or fifteenth century, and towards the close of the sixteenth century it was introduced into other European countries. In France, especially, the manufacture flourished in COLBERT'S celebrated manufactory at St. Cloud. The only improvement of importance which has since been made in the original processes was introduced by CURANDEAU, who saved much time, labor, and expense by substituting sulphuric acid for alum. His method is, after preparing the skins in the usual manner, to immerse them for twenty-four hours in a lye composed of four pounds of sulphuric acid mixed with twenty pounds of salt, and twenty-five gallons of water, the same lye serving for several different lots of hides. Heavy ox hides are most frequently used, but other descriptions may, with advantage, be subjected to this Hungarian process.

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A writer in one of the German scientific magazines gives it as his opinion, founded on carefully conducted experiments, that the diamond is the product of condensed carbon, chrystalized from liquid carbonic acid. It is known that dia monds not rarely show cavities, in which, according to all appearances, a considerable pressure must have taken place. Supposing these cavities to contain some kind of gas, it is argued that there is no reason why this might not be carbonic acid under a high pressure; and this theory would furnish a ready explanation, it is thought, of the color-rings with black crossings observed around the cavities in diamonds, by supposing them to be caused in a similar manner as those of unevenly compressed glass. The carbonic acid then stands in the same relation to diamonds, as the mother lye, inclosed in a number of artificial and native crystals. That there are large quantities of carbonic acid under a high pressure in the body of our planet, is shown by the immense quantities escaping at varions localities.

REMAINS OF ANCIENT SALT WORKS IN THE SALINES OF ILLINOIS.

Dr. DAVIS has received a letter from Mr. SELLERS, a scientific gentleman in charge of some of the Salines in Illinois, and has discovered various articles sunken in the earth, which were used at some long past period by people unknown in making salt from the same springs which are now recently brought into use. The letter contains descriptions of utensils and instruments found, particularly fragments of the largest ancient earthen jars ever discovered in our country. It also gives a description of the process which must have been pursued by the un. known manufacturers in procuring salt from the waters. Such discoveries, with the intelligent and interesting conclusions to which the writer was led by the facts, add new inducements to the labors of investigators.

BARKS FOR TANNING.

The following is a very useful and interesting summary of the different barks used in tanning :

There are four species of oak barks chiefly used in tanning. The first is the Spanish oak, which thrives in Maryland, Delaware, and Virginia, and in all the States south of 41° N. In the Atlantic States this species is most abundant, and in Georgia and the Carolinas it is known by the name of "red oak." Its bark, which is thick, black, and deeply furrowed, is preferred for coarse leather, which it makes more pliable and of a better color. Hemlock bark is often with advantage mixed with it. In the Southern States, the Spanish oak grows to the height of eighty feet, having a trunk four or five feet in diameter; while in some of the Northern States it does not exceed thirty feet in height, with a diameter of five or six inches.

The common red oak grows abundantly in Canada and in the Northern States,⚫ especially in the southern half of New York, in New Jersey, in northern Pennsylvania, and along the ridge of the Alleghanies. Its bark is very generally employed, though inferior in several respects to some other kinds. This tree grows to the height of seventy or eighty feet, and has a diameter of three or four feet. The rock-chestnut oak is seldom found in the Southern States, but abounds in elevated districts having a broken, rocky surface. On some of the Alleghany Mountains it constitutes nine-tenths of the forest growth. Hence the name "rock oak," by which it is known on the banks of the Hudson and on the shores of Lake Champlain. It has received in Pennsylvania, Maryland, and Virginia the name of "chestnut oak." Its bark is thick, hard, and deeply furrowed, and differs from other barks in that the epidermis or outer layer contains a large proportion of tannin, which is usually in other kinds confined chiefly to the under layers. In Pennsylvania and New York it abounds, but only the bark of the small branches and young trees is used in tanning.

The quercitron or black oak grows throughout the States, below the latitude of 43° Ñ.. and in the more elevated sections of Georgia and the Carolinas. Its bark is not very thick, but is bitter, deeply furrowed, and of a deep brown or black color. It also imparts a yellow color to the ooze; and leather tanned with it is apt to give a yellow tinge to the stockings. This inconvenience, however, may be obviated by an inexpensive chemical process. Quercitron bark is much used, as it is abundant, cheap, and rich in tannin. This tree often attains a height of ninety feet, and a diameter of four or five feet.

Besides these four kinds are others less known. The white oak chiefly grows in Florida, and to the south of 46° N. Its bark is preferred for leather for saddles, and similar purposes. The scarlet oak is found as far north as latitude 43° N.; its bark is very thick. The gray oak in Maine, New Hampshire, and Vermont; and the live oak is never found more than twenty miles inland; its bark being black, hard, thick, and replete with tannin. Other kinds of oak bark are occasionally used, but not to any great extent in the United States.

Most of the sole leather in our country is tanned with the bark of the hemlock tree, which is unknown in the Old World. The common British oak grows in almost every country in Europe, and is the chief agent used in tanning. It some times reaches a height of one hundred feet, and the trunk grows occasionally to fifteen feet or more in circumference. This majestic tree will stand hundreds of years, and when at a distance from other trees, it spreads its gnarled branches so that its head is often broader than its height. The foliage resembles that of the white oak of this country. In northern Russia, and in some parts of France, the bark of a shrub called the Kermes oak is used in tanning. This shrub grows to the height of three to five feet, and bears some resemblance to a small holly tree. The bark of the root is rich in tannin, and is said to produce a very superior quality of thick, durable, impervious sole leather.

In early spring, the opening leaves indicate that the sap is circulating the most actively, and it is found that the bark then contains nearly one-third more tannin than in autumn, consequently in this country, the proper time for barking trees

will vary, according to latitude and other circumstances, from the end of April to the beginning of July. Wet seasons and damp localities are prejudicial to the bark, and lessen its tanning power. The bark of southern oaks and of such as grow in high elevated positions is more rich in tannin than that of low and badly drained, damp, and shady locations. In hemlock bark the inner layer contains about 8 per cent of tannin, the middle part about 5 per cent, and the outer part about 3 per cent.

STRENGTH OF GLASS.

A series of interesting experiments has recently been made in England, in regard to the tenacity, strength, &c., of glass. The experiments upon the direct tenacity of glass made by tearing specimens asunder, were less satisfactory or reliable than others; and it is stated that more reliance is to be placed upon the ⚫ tenacity deduced from the experiments on the resistance of globes to bursting, than upon the tenacity obtained directly by tearing specimens asunder. The latter method gave the following mean results of tenacity per square inch, in pounds :-Flint glass, 2,413; green glass, 2,896; crown glass, 2,916. The experiments in regard to the resistance of glass to crushing, were made upon small cylinders and cubes of glass crushed between parallel steel surfaces by means of a lever. The cylinders were cut of the required length from rods drawn to the required diameter, when molten and then annealed, in this way retaining the exterior and first coated skin of glass. The cubes were cut from much larger portions, and were, in consequence, probably in a less perfect condition as regards annealing. The specimens were crushed almost to powder by the violence of the concussion; it appeared, however, that the fracture occurred in vertical planes, splitting up the specimen in all directions. Cracks were noticed to form some time before the specimen finally gave way; then these rapidly increased in number, splitting the glass into innumerable prisms, which finally bent or broke, and the specimen was destroyed. The mean resistance to crushing of the flint glass, was, in pounds, 13,190; of green glass, 20,206; of crown glass, 21,867.

HEAT OF DIFFERENT WOODS.

The following is set down as the relative heating values of different kinds of American wood:- Shellbark hickory, being taken as the highest standard, 100; pig-nut-hickory, 95; white-oak, 84; white-ash, 77; dog-wood, 75; scrub-oak, 73; white-hazel, 72; apple-tree, 70; red-oak, 69; white beech, 65; black-walnut, 66; black-birch, 62; yellow-oak, 60; hard-maple, 59; white-elm, 58; redcedar, 50; wild-cherry, 55; yellow-pine, 54; chestnut, 52; yellow-poplar, 52; butternut, 52; white-birch, 49; white-pine, 42.

Some woods are softer and lighter than others, the hard and heavier having their fibers more densely packed together. But the same species of wood may vary in density according to the conditions of its growth. Those woods which grow in forests, or in rich wet grounds, are less consolidated than such as stand in open fields, or grow slowly upon dry, barren soils. There are two stages in the burning of the wood. In the first, the heat comes chiefly from flame; in the second, from red hot coals. Soft woods are much more active in the first stage than the hard, and hard woods more active in the second stage than soft. The soft woods burn with a voluminous flame, and leave but little coal, while hard woods produce less flame and a larger mass of coal.

SORGHO DYE.

A. WINTER, of Austria, has discovered a carmine-coloring matter in most parts of the Chinese sorgho, especially in the expressed stem, and has obtained a patent in Austria, Baden, and other States. The process is as follows :-The sorgho is pressed in the usual manner, and the empty cane piled up under cover in regular heaps, several feet high, and the fermentation which immediately sets in is so directed by more or less access of air as to prevent it from becoming putrid. After two weeks the whole mass is of a reddish brown or red color, when the fermentation is interrupted by drying. When dry, the mass is ground sufficiently fine for the extraction of the coloring matter. It is covered in the proper vessels with cold soft water, and allowed to stand for twelve hours; but little of the pigment dissolves during that time. It is then drained and afterwards treated with a weak caustic soda or potash lye until this no longer extracts anything. This solution is carefully neutralized with sulphuric acid, thus precipitating the coloring matter in red flakes, which, after settling, is washed with water, collected on filters, and dried. This color dissolves in alcohol, alkaline lyes, dilute acids, &c., and is employed for the dying of silks and woolens with the common tin mordants. The colors produced from it are said to be unchanged by light or by washing with warm soap-suds.

IRON WORKS IN THE UNITED STATES.

From a table compiled by the American Iron Association, exhibiting the number of iron works, idle and in operation, in the United States, it appears that there are furnaces, rolling mills, or forges in twenty-five of the States of the Union, leaving but eight States destitute of iron works; these are Mississippi, Louisiana, Florida, Texas, Iowa, Minnesota, California, and Oregon, all upon the boundary or frontier. The following are the totals :

Working..
Abandoned..

In all......

Rolling

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Forges. mills. 389

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These produce annually about 840,000 tons of iron, the value of which, in an ordinary year, is fifty millions of dollars. Of this amount, the portion expended for labor alone is $35,000,000.

ARIZONA SILVER.

The St. Louis Democrat of a late date remarks:- -We had the pleasure last evening of a visit from Hon. SYLVESTER MOWRY, lately elected delegate to Congress from Arizona. Lieut. MowRY arrived by the last overland stage, and is en route for Washington city. He brings with him about forty-six pounds of silver from that territory. It consists of various specimens, from the moulded plates to the common sample, as are found in Arizona-pure silver, after the mercury is expelled, reduced by amalgamation; silver reduced by melting and run in sand moulds; silver and copper ore, and a large quantity of rough silver ore from the mountains in the Rio Grande valley, twelve miles from the river, near the celebrated Stevenson mine. The whole region promises a rich yield. The ores are principally argentiferous galena, and reduced to a pure plate at a very small cost.

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