From the Report of J. Lawrence Smith, United States Commibsioner to Paris Exposition.Fmnace for Burning Pyrites.—There .is nothing specially new in the present construction of furnaces used for burning pyrites, but as these are scarcely used in America, but per - haps can be with advantage, it is well to refer to them here. At first fuel was mixed with the pyrites to keep up the combustion, but this was soon abandoned, and it is foun; that pyrites in burning furnishes all the heat necessary to continue the combustion. The beds of pyrites are made quite thick ; at Javelle, France, they are made over three feet thick, and the doors of tile 'urn ace are luted. The combustion goes on very slowly, so that forty-eight hours art- required for the upper layer of the pyrites to descend to the grate bars. In this way most complete combustion is procured, and hardly two or three per cent of sulphur remain , in the residue. However, to accomplish th is complete combustion, the pyrites must be in lumps ; but as the pyrites if obtained about 10 per cent of it is more or less pulverized, constituting one of the annoyances in this method of making Sulphuric acid. Various methods and furnaces are in use for the combustion of this fine pyrites, and they accomplish the result more or less perfectly. The furnace of Sfence, used almost universally at Manchester, is probably the best for this purpose. This furnace is a very long one, from forty to fi fty feet long by six feet wide, and inclined about fifteen inches downwards. The floor of the furnace is of large flat tiles, and is heated from below by a lateral furnace three or four feet in advance of - the lowest part. The fine pyrites is introduced by an opening in the top of the furnace, and is spread by means Of rakes introduced through a lateral door only opened during the raking, and when it is necessary, by skillful movement, to push forward the pyrites to the lower part the furnace. After being allowed to cool, it is drawn out of the furnace, at the front part, through an opening that supplies the requisite quantity of air by adjustment. The roasting lasts about twenty-fo ur hours—the furnace having twelve doors on the side, and two hours being al'owed to the pyrites between each door before it is pushed forward. It is said that the fine pyrites can be made to give up all but two or thre 3 per cent of its sulphur, .. result not far from what is realized with that in lumps ; and when it is remembered that this fine pyrites bears a less price than that in lumps, th se results a re certainly of vast importance to the large factories. Kuhlmann, in his process, mixes the fine pyrites with clay, and makes small balls or cakes, that, after drying, are used in the same furnace in which he burns the lump pyrites. Five per cent of clay is sufficient to mix with the fine pyrites to form the little balls, and they can be made at a cost of about forty cents a tun in France. The furnace that Michael Perret has introduood for burning fine pyrites in several establishments in France is highly Spoken of Instead of using the long furnace of Spence, he divides the turnace int) a number of shelves, with large fire tiles, six centimeters thick and ten centimeters apart, and so placed in the masonry that the hot air and gases proceeding directly from the pyrites in lump, burning in the ordinary furnace, circulate back and forth (ascendin g all the time) over these shelves, on which the fine pyrites is spread to a depth of three centimeters. We may have ten or more of these shelves, until the furnace becomes inconveniently high, The operation lasts thirty-six hours, and each furnace can bum one tun of fine pyrites. This system is said to require •one per cent more of niter in the subsequent operations. Purnace of Gerstenlioffer.—We cannot omit giving a passing notice of the furnace of Gerstenhoffer, of Freiberg, which is employed by the Vieille Montagne Company, of is filled into one compartment, and the solution of tartaric France, and also at Swansea, in Wales. At the last-named place it is used for desulphurizing copper ores containing 30 per cent of sulphur, and Irom which they are now collecting the sulphurous acid and making sulphuric acid. The furnace is composed of a quadrangular tower eighty centimeters square and six meters high, closed at the top, except a long, narrow opening extending from one side to the other. Above this opening is placed a hopper of the same length, provided with two feel rollers at the bottom, the movement of which feeds the furnace w t'l pulverized pyrites. This pyrites, as it enters the furnace, falls on a triangular prism or oross-bar of brick fastened horizontally to the walls of the furnace, with its base uppermost. The powder gradually accumulates on this horizontal face, so as to make a pile with a triangular secti m, the base of which covers the face of the prism. After a short while the pyrites falls ov. r on each side of the prism in two thi n sheets, which, n descending, meet.with two oth!lJ' prisms below so placed 'IS to intercept it and cause it to accumulate again, and afterwards to fall over in four sheets, and so- on. By successive lescents over as many as twenty prisms \he pyrites is nought thoroughly in contact with the heat and air of the furnace, and by the time it reaches the bottom there is not more than four or five per cent of sulphur left in it. By openings, clos d by movable stoppers in the side of the furnace, the process of oxidation of the pyrites can be seen, and tl1e influx of air can be regul ated. Utilizing- the Residue from the Pyrites Furnace.—This residue, notwithstanding the little sulphur remaining in it, is ised in the high furnace, mixed with ores for the production if iron. Mr. Bell, near Newcastle, and Perret in his operations, has shown that by the addition of a little common salt ,n the desulphurizing process, iron of a good quality can be nade from this material. When this waste product from ;;he manufacture of sulphuric acid becomes useful in a remunerative industry, another great impulse is given to the production of this. acid from pyrites. The< Use of Fluxes la tne Reduction ot Iron Ores. The principle upon which the use of all earthy fluxes is based, is, that, practically, no earth is fusible alone ; argillaceous and silicious earths together are infusible, so with 1 rgi l 'aceous and magnesian—so with silicious magnesian, but, when calcareous earth, lime, or limestone, is added to any mixture of the other two, all will combine and run into glass, vhich will become thin, with the same heat, according to the skill in proporti on and treatment. M. D'Arctt, a French chemist, made this experiment: He put into three crucibles, respectively, a ball o'f clay, a quartzose, or silicious sandstone ball, and a limestone or chalk ball, and exposed them to heat so great that the chalk ball fused slightly, where it had touched the sides )f the crucible. They were unmelted. He tl-en mixed them, md, in the same fire, they ran into a thin and transparent Kirwan found that argillaceous and magnesian, argillaceous and silicious, and silicious and magnesian earths would !lot melt in any proportion, but that silicious and calcareous earth s, argillaceous and 'calcareous, by very strong heat, would vitrify, but not perfectly. When the earth s are calcareous, argillaceous and magnesian, it requires a double proportion of the calcareous to make a glass. No g1ass can be made if the clay earth, or magnesian predominate. It has been found that the calcareous earth, argillaceous and silicious earths, or calcareous, magnesian, and silicious can be brought into perfect fusion, if the calcareous somewhat predominate. With a strong heat, argillaceous, silicious, and magnesian earths may form a glass without lime, and this ;s the only combination he tried that would thus produce glass without lime. The metallic oxides (iron, of course, included) aided the fusion. Note, that, common clay sometimes contains one half, or more, of its weight of sand intimately mixed. If clay predominate in the iron ore the flux indicated is limestone, and if the iron be, on the contrary, mixed with limestone, the proper flux is not limestone, but olay. Herein consists much of the practical knowledge in mixing ores so that they may flux one another, which are with diffi culty fluxed alone. Hence the I ecessity of a knowledge of the composition of ores to prevent the loss of fuel, of time, and of iron, by the iron becoming entangled in the scoria, or in a thick unyielding slag.—OBborn's Metallurgy of Iron. Chemical .Fire Engines. state;! that the principle of extinguishing fires by the use of water saturated with carbonic acid, has recently been extended by a Glasgow firm to engines, which can be worked either by manual or steam power, in such a way that the component parts required for the generation of the gas are forced separately into a vessel within which they mix, and pass beneath the self-created pressure through the hose and nozzles in connection with the machine. The apparatus comprises a wheeled carriage, the body of which is in the form of a tank made with sheet iron fixed upon angle- iron frames, and which is divided into three compartments. Pumps are fitted into the compartments, and are arranged to be actuated by a beam, on a rocking shaft which is provided with the usual levers for the application of manual power. The pumps may, however, be worked by a portable steam engine, as in existing steam fire engines. The commnnica- tions with the pumps are so arranged that they may draw from the tank compartments, by openings, in which case the liquids used are filled into those compartments, that is, the solution of carbonate of soda or other suitable carbonate acid is fiUed into the o'ther compartment. Or the openings may bg closed and the liquids may be drawn from other tanks or vessels by means of hose coupled to the ends of the pipes projecting out through the back ol the carriage for the purpose. Air vessels, for equalizing the flow of the liquids are applied to the suction pipes. The delivery pipes from the pumps lead into Ijo strong tessel in the front bompart- ment, and in connection with this vessel there is a single delivery pipej upon the projecting end of which the hose is to be coupled for leading the gas and water to the fire. A vessel receives the two liquids delivered by the pumps, and these liquids act upon each other in the vessel or generator, as it may be termed, and generate or set free the carbonic acid of the carbonate employed. This carbonic acid passes off along with the liquid and is by the hose directed Upon the fire, against which it is thus in a most effectual manner made to exHcise its well-known extinguishin g power. The arrangement of the various parts of the apparatus may be modified, and will depend more or less on the power intended to be developed. Thus the chemical liquids employed may form only a part of the liquid employed by the engine, water from any ordinary source being also pumped into the generator or delivery pipe either by separate pumps or by the same pumps ; separate suction pipes being used in the latter case with valves or cocks to re^^ ate the quantities of chemical liquids drawn in along with the simple water. Or, on the other hand, the two chemical liquids m ay be forced into the generator by separate and distinct pumping engines arranged upon the same or separate carriages. The experiments which have been conducted with this machine show that it possesses in an extended form the merits of the smaller apparatus. The water and carbonic acid gas co mbined produce a far greater effect upon a fire than an equal bulk of unmixed water—an important consideration, for it happens not unfrilquently that the means used for the extinction of fires are productive of as much d. mage as the fires themselves. A series of trials will shortly be conducted with the new chemical engines, and we shall then be able to ascertain the advantages they will actually offer over ordinary engines. Damp Walls. ” Our attention,” says the Mechanics' Magazine,” has of' late been called to the question of rendering the walls of buildings impervious to moisture. We have received letters upon the subject from correspondents who ask us to point out a remedy for the evil. We, therefore, gladly take the opportunity of making known to our readers that there is a remedy, at once simple and efficacious. This is a process invented by Mr. Frederick Ransome, and which is being successfully carried out in practice by the Patent Stone Company, 'East Greenwich. It consists in the employment of colorless mineral solutions which possess the property of forming an insoluble and indestructible mineral precipitate when applied to bui l dings. The deposit takes place not only on the surface of the material t", which it is applied, but enters the body of the substance. The application of the solution in no way alters the color of the material, a perfectly natural appearance being preserved in the building. The effect is permanent, neither atmospheric nor saline influences in the least degree affecting the indurating material. It not only renders the building water-proof, but it further most effectually indurates and preserves from decay the stone or bricks treated with it. . This process has recently been applied to sevtral buildings which are stated to have been untenantable, previously to the application, on account of exposure to a wind- driven rain. Paper now hangs well on the walls from which it formerly drooped in festoons and tatters, while dryness and a cleanly appearance have taken tlJe place of dampness and mildew. This process of rendering buildings impervious to wet is comparatively inexpensive, therefore no one need l onger to suffer from that source of discomfort and danger to health —damp walls. Narrow Gage Railway. The Portmadoc and Festiniog Railway, Wales, is now at tracting much attention from railroad men. This is a little line in North Wales, which was originally constructed for the purpose of acting as a tramway for slate and stone from the hills of Merion ethshire to the sea shore. It is now being used as a regular goods and passenger line. The chief peculiarity in its construction is that the gage is only two feet broad. Hence, though the line runs through a very difficult country, the expenses of construction and working are so small that the traffic yields the enormous revenue of thirty per cent. The reason is simple enough. It is because the proportion between the dead weight and paying weight is so much less than upon other rail ways. The engine and tender upon this line weigh about ten tuns, against forty tuns upon the wider gage of other lines. Instead of a first class carriage weighing seven and a half tun s, to carry thirty-two passengers, and representing nearly five cwt. of dead weight for each passenger, the carriages on the Festiniog weigh only th:rty cwt. for twelve passengers, or two and a half cwt. for each person carried. Effect of Steam Heat on Hay.—A correspondent from Rancocas, N. J., favors us with a specimen of hay wrappin g which had been' on a steam pipe for nine years ; 1 he pipe carrying steam at fifty-five lbs. The specimen is of a chocolate brown and very friable ; but it burns no more readily than well dried fresh hay, although its appearance would seem to indicate great combustibility. We should have less fear of its ignition than of pine wood similarly carbonized. © 1869 SCIENTIFIC AMERICAN, INC308 Jcit [November 13, 1869. In^rovecl Implement Cor Opining Cans. The want ''of a perffectly efficient, handy, and light tool for opening tin cans containing fruits, vegotables, etc., has been long felt. The practice of preserving fruits, meats, etc., in thismanner has become general, and something of this kind is needed in almost every house. The engraving tells its own tale. The instrument consists of two small levers, A and B, pivoted together at C. The pivot, C, is bent at right angles, “and made sharp to act as a center punch. Two blades, D and E, are held by clips and set screws to these levers, one blade being set at right angles to the other, These blades are adj ustable to different diameters of cans. In use the instrument is seized with both hands in the manner shown in the engraving-, the center, C, is first punched vertically through the top of the can. The handles are then brought to a horizontal position, and the blade, E, is thrust through the tin, making a radial cut, shown at F. The center, C, and the blade, E, now hold the can from turning, while the lever, A, is made to perform a complete revolution, carrying with it the blade, D, and cutting out the top in a remarkably neat manner. There is no liability of the can's turning, as in the case with many instruments made for this purpose, and thus a great annoyance is completely obviated. Patented through the Scientific American Patent Agency, Oct. 19, 1869, by W. M. Bleak- ley, whom address for further information at Verplank, N. Y Steam on Common Roads, In England, steam begins to be used on the common roads. A gentleman writes to the Times stating that he has received a visit in the dead of the night from Jl, friend, who with four members of his family arrived in a steam wagonette. The reason for selecting that unearthly time for the visit was the existence of a law forbidding the use of steam carriages on the public thoroughfares except between the hours of ten at ni ght and six in the morning, also limiting them to a speed of two miles an hour, and requiring them to be preceded by a man sixty yards in advance bearing a red flag. The writer suggests that these precautions are unnecessary, and that steam locomotives should be allowed the use of the roads at all hours, with no other precaution than a limitation of speed to twelve miles an hour. On this the Pall Mall Gazette remarks: ” If steam wagonettes are coming into general use, we earnestly hope that there may be some modification of the law referred to, but only for the sake of the visited. We are all delighted to receive morning visits from our friends, but there are cases in which we should be more delighted to be let alone, and we tremble to think what will be the effect of a host of visitors arriving in the early hours of the morningln steam wa^nettes at the rate of two miles an hour, preceded by heralds with red flags. Whynot transfer these restrictions from steam carriages to wagons, which are the cause of most of our street accidents? It would be an admirable plan to limit the speed of these vehicles and insist on their being preceded by a signal of danger," Tbe New York and Brooklyn! [Bridge. The contract for building the caisson or foundation work of the bridge on the Brooklyn side has been awarded to the firm of Webb&B^l, of Greenpoint. The cost, with the necessary timbers, isto be about $200,000. The work is to be commenced immediately undal' the general superintendence of Mr William C. Kingsley, of the firm of Kingsley&Keeney. The central part of the tower on the Brooklyn side will be located at the upper slip of the Fulton Ferry. All the woodwork of the old docks and piers will be torn up, and every thing removed to low water tide. The bottom of the river will then be excavated to a depth of 22 feet below high tide, until a level area is obtained for the reception of the caisson. The dimensions of the caisson, the space to be thus cleared and leveled, is 170 feet long by 102 feet extending out into the river toward New York. The 102 feet front of the caisson, facing that city, will be on a level with the bulk head line'as established by the Harbor Commissioners. The maSs of large boulders with whi!lh the bottom of the river is believed to abound will be removed by blasting, and the pieces removed by powerful dredging machines. Experiments which have been made on the quicksand bed of the East River, while excavating a dry dock, prove its bearing power to be ten tuns per square foot. By'Mr. Roebling's plan, it is proposed to rest upon this bed a weight of only four tuns per square foot. The weight of each tower is to be somewhat over 75,000 tuns. To distribute this vast weight so that no part of the pressure on the base shall be over four tuns per foot, it has been decided that the area of the foundation shall be 170 feet long by 102 feet broad. This area will be composed of huge timbers resting on the sand, and bearing the masonry work of the tower upon it. The timber will be 30 feet thick, and this vast mass of 20 feet by 170 by 102 will be securely bolted into one solid frame, so that the weight of the tower above can never deflect in the slightest degree at any point. The caisson, when launched, will draw 17 feet of water. It will be 170 feet long, 102 feet wide, and 15 feet deep, with a top five feet thick, and sides of a thickness tapering from 9 feet at the top to a foot below. The time required to build it will be about four months. As soon as it has been set afloat it will sink to within eighteen inches of tha surface of thfe water and when the proper time arrives it will be towed down to the ferry and placed in position ready for being submerged. This is to be accomplished by building on the top of the caisson successive layers of timber and concrete to a hight of 20 feet. The weight of the caisson with this 20 feet of timber and cement above the “ air chamber,” will be 11,000 tuns. The material excavated is hoisted from the “ air chamber” through two water shafts by means of dredges, and as it is raised the caisson sinks, being uniformly undermined round the four edges and throughout its whole extent. As the caisson thus gradually sinks the mason work, inclosed in a coffer dam, is in progress on the top of the timber, thus adding the necessary weight. Access is had to this “ air chamber” by means of two air shafts three feet in diameter. The depth to which it will be probably necessary to go into the BLEAKLEY'S CAN OPENER. bed of the river, will be about 55 feet belowhigh watermark, so that all the timber of the foundation will be inclosed in the sand and other material through which an excavation has been made.