Volume 35 (1877) (426 pages)

Soe” Bee ea as Se ons ee ET ae ae ee A YS _ ceptible of otber applications. October 27, 1877.] MINING AND SCIENTIFIC PRESS 259 — = == : Koy WecHanicat ‘PRocress. The Cause of Blisters on Steel In tho process of making steel, whieh is so largely practised at Shetlield, bars of iron, usually of Swedish of Russian manufacture, are imbedded in chareoal powder, and kept heated to bright reduess during about a week or ten days, aceording to the degree of carbnrization desired. Carbon is therchy imparted to the iron, and ateelis tho product. The bars operated upon aro generally abont threo inelics broad and tlireefourtha of an inch thick. Ifow the carbon finds its way even to the eenter of such bars, is a questiou not yet satisfactorily solved, though it possesses high scientifie interest, and has been mueh discussed. At tho late mevting of the English Iron and Steel Instituto, a paper was real by Dr. Percy, the object of which was to communicate to tho Institute experimental evidenees as to the cause of the siugular phenom. enon which accompanies this process of convertiug iron into steel, viz., tho ovcureneo of blisterlike protuberances on the surfaces of the bars. This appearance is so characteristic and so constant, that the name of “‘blister-stcel” is applied to such bars. The protuberances are hellos, exactly like blisters, aud vary much, hoth in numbor and size; some are not larger than peas, whilo otbers may exceed au incb in dismeter, and they are always confined to the surface of tho bars, for there is a specimen of ‘‘blistersteel” in Dr. Percy’s collection, in which tbore is asingle blister as large as a small hen’s egg, protruding equally from each of tbe opposite surfaces of the har. Dr. Percy concluded that it had been conclusively proved that all bar iron manufactured by eharconl finery processes, or by puddling, must contain, intermixed, some of tbo slag, which results from tbe conversion of Pig-iron into malleable iron hy such processes, in which, let it be remembered, the malleabe iron is never actually melted. On a visit to the great steel works of Messrs. Firtb, at Sbeffield, in February last, Mr. Chas. Hi. Firth undertook at Dr. Percy’s suggestion, to settle the question whither hlistering would occur in the converting process in the case of a bar of iron which had heen actually melted and so freed from all intermixture of ferrous silicate or mnagnetic oxide of iron. The experiment, says Dr. Percy, ‘‘was accordingly made, and with good effect, of confirming, and, I think I might almost say, estahlishing the correctness of the explanation which I ventured to submit concerning tho cause of the formation of the blisters. On the 9th of last May, Mr. Firth informed me that be had melted Swedish bar iron, and cast it into a flat ingot, which be bad carburized in the converting furnace in the usual manuer; and, at the same time, he forwarded to me a piece broken from the ingot after conversion; this piece was about six inches long, three inebes hroad, and a little more than half an inch thick; it showed a fracture at each end, characteristic of converted steel, but there was not the sligbtest indication of a blister.” METHOD OF SHRINKING on TirEs.—The beating of tires by means of hot water instead of by direct contact with fire is brought forward tbrougb Englisb sonrces. It has thus far been applied to railroad work, but possibly it is susThe record of tbe late experiments is as follows: Tbe expansion of tires by bot water, though not elaimed to be new, is believed by tbe anthor to be much superior to the ordinary method of using fire. As applied on the Moscow-Nijni railway, an iron tank, one-fourth filled witb water, is fixed near a stationary boiler, a steam pipe from which is led tbrough it, capable of heating the water to 212° Fahr. Into this tbe tire is plunged by means of a portable crane, and after an immersion of from 10 to 15 minutes, is taken out and immediately placed on the wheel. Three men only are employed, who will fix from 12 to 14 tires in a day of 11 bours. The allowance for sbrinking (the difference between the diameter of the skeleton and that of the tire) is 0.75 millimeter to a meter. This is ascertained by gauges of great accuracy, and, if deviated from, tbe tire wall be either loose after cooling or too small to get on the wheel. When fire is used, the tire can never be heated equally or cooled equally in all parts, and, in consequence is sure to he more or less oval in form, which is not tbe case in bot water. Tbe above railway made a comparison between the two, tbe results of which are given. It appears that, during a six years’ trial of fire-shrunken tires, 37% ran loose and 5% were broken; while, during a three-years’ trial of water-shrunken tires, less than 1% ran loose and only a single tire was broken, The liability to breakage in the former (produced by the irregularity in form) is much insisted on by tbe author as being, of eourse, far more dangerous and costly than the mere loosening of the tire. River Bep Minixc.—About 50 ancbors and an immense quantity of chain were raised from the hed of the St. Lawrence river, Quebec, recently. This nest of iron was the accumulation of years, and took the lifting barge about a month to effect the raising. Export Trade in American Manufactures. There receutly assembled in Philadelphia a body of men couneeted witb our mauufacturing interests, forming “‘s convention of the asso. eiated industries of the United States.” We kuow nothing of the association, except that the Western Manufacturer speaks in favor of it. We read that it devoted timo te devising ways and means for practically relieving our overcrowded markets, and paving tho way for a large production, and thus providing for tho employment of the bhoil santa of workingmen now idle, and sufferiug all the hardships of sueh a condition, A committeo was appoiuted to make investigatious in regard to foreign markete with a view to increasing our export trado, to place samples of American mauuinctures in all foreign markets, aud demonstrate their superiority over those of other nations, and also to learn and report the special kind and quslity of goods most in demand amoug nations with whom we have heretofore had little or uo trnde. This eommittce in a report already submitted, say: “Enough has already‘been dono to justify the present reference to it, and to show the need of some precautious, In the few months ofthe present year, the direct export of Philadelphia inanufactures in new articles, not sent in any quantity previously, is about two millions of dollars in value, and tbe indirect export hy way of New York\ much greater, so many being sent there for sbipment.” Among tbe classes of manufactures in which an export trade has been established, may be mentioned “‘wood-working machinery, bydraulic works, inclnding pumps, the bigher fornis of agricultural implements, house building and bridge building appliances, cotton and woolen machinery, cotton prints, bleached cottons, ginghams, and various forms of colored cottons, cotton mixed goods, worsted goods of various classes, gas meters and gas works, carriages and carriage equipments, leather, ladies’ snd children’s shoes, oil cloths, hats, caps and straw goods, drngs, paints, books, paper and stationery, scales Bea! balances, hardware and tools of every class, lawn mowers, etc.” ArniviciaL Biack Watxut. — A Belgian journal says a new process has been applied to tbe manufacture of artificial black walnut, by which ordinary wood has imparted to it the appearance of the most beautifnl specunens of walnut, adapted to the very finest cahinet work. The wood, first thoroughly dried and warmed, is coated once or twice with a liquid composed of one part by weight of extract of walnut peel, dissolved in six parts of soft water, by heating it to boiling, aud stirring. The wood thus treated is, when half dry, brushed with a solution of one part by weight of hichromate of le in five parts of boiliug water, and, after rying thoronghly, is ruhbed and polished. The color is thus said to be fixed in the wood toa depth of one or two liues, and, in the case of red beech or alder, for instance, the waluut appearance is most perfect. Fioorine Trtes or AsrHatr.—The London Building News states tbat at the Bavarian Industrial Museum may be seen a collection of square tiles of asphalt prepared by a new process, and intended for floorings. The tiles are ornamented with mosaic, in white china or colored glass, which may be arranged according to any design, The drawing to be reproduced is traced on a sheet of thick paper, which is afterward covered with the various fragments of china or glass, which will form the mosaic; a border is made to the sbeet, and boiling aspbalt poured upon it. After the whole is cooled, the paper is taken away with cold water, and the tile is finished. A flooring covered with such tiles hound together by a string of aspbalt appears to have been made bya single melting, and has a good appearance. It indelinitely resists damp, and is consequently useful in bathrooms, halls of houses and balconies. IMPROVEMENTS IN THE CAPITOL AT WASHINGton.—The American Architect says tbat the new ventilating and heating apparatns of the hall of the House of Representatives has proved to be a great success. ‘The new plan was introduced by Edward Clark, arcbitect of the Capitol, in accordance witb the report of the board of United States officers, convened atthe request of the Committee on Public Buildings in the last House. An appropriation of $33,000 was then made. The fresh air is now taken direct from the grounds of the capitol, through the terrace, and is tempered by the warm air in winter from tbe hot water coils, while in summer it is thrown iuto the building direct from the grounds. A series of ventilators to. carry off the foul air bave taken the place of some ornamental pendants in tbe ceiling. Svunsrvrure ror Link Morion.—The master mechanic of the Midland railroad sbops at Norjvich, Conn., is reported to bave invented a substitute for the ‘‘link motion,” which employs but one eccentric, and accomplishes all which that famous method of working valves does without its complication, and with the expenditure of less power. The link motion is in itself so perfect, so simple and so admirably adapted to the uses to which it is put, whether upon the locomotive or mariue engine, tbat it is almost impossihle to eredit the statement in regard to this invention. Although so nearly perfect, the link motion is still susceptible of very material improvement, and it is quite probable that in time it may be greatly molitiea witb advantage. ra ey BcIENTIFIC P RoGRESS. The Value of Science to Artisans. At tbe annual meeting of the Birmingham and Midland Iustitute, Euglaud, the chairinan, Mr, J. Thackeray Bunce, in the course of his address spoke at some length ou whist wo may term the commercial valuc of seientifie knowledge, or on tho value of thnt kiud of informa. tion to those engaged in manufactures aud industrial pursuits of all kinds. We quote the following emiuently true paragraphs: ‘‘By a study of science at this time, we do not mean study in its highest and best sense, s search after knowledge for its own sake, but that amount of study which is undertaken for the advantago it gives in competition witb other niauufacturers or professionals, and with other uations. Asa nation we must he workers, producers; we csnnot afford to wauder about tbe by-ways of learning for the mere pleasure of gaining knowledge; we must, or the great majority of us must, tread the broad roads already graded and laid out by previous workers, pieking up all the information we can, and storing it . 4 in orderly fashion in our mental wallets for use by snd by. Others among us—a gradually increasing number—will strike out paths for themselves across untrodden fields, and seek for new treasures with more or less success, We cannot all make rescarches and experiments, nor are we all fitted forthe work; but we can all learn sometbing of what is known already, and so prepare ourselves to take advantage of and utilize the discoveries of scientific investigators. Every artisan in the kingdom can, if be will, make himself acquainted with the principles on which the practices with whicb he is familiar are based, aud there is uo industry in the eonntry which would not be benefited by such knowledge on the part of its workers, In a few years now a considerable portion of our workers will be men who are more or less well grounded in theory; they are receiving a technical education, and when they enter the ranks of the industrial army they must, in tbe natural order of things, occupy prominent places. Even now Whitworth’s scholars, at present a comparatively small numher, make their way readily to the frout, and in competition with mere rule-ofthumb men gain an easy victory. Optical Characters of Minerals, A new method of studying characters of minerals was lately described hy Mr. Sorby, F. R. S., in a paper read before the British Association. Theautbor first descrihed the princibles on which the method depended, and that the great difference between the appearance seen with the naked eye and the microscopeis due to the object glass being able to collect divergent rays. Iu looking with alow magnifying power at a small circular hole seen through a section of a crystal, very different phenomena present themselves, according to its optical characters. If double refraction only one well-defined circular hole can be seen. If the mineral possess douhle refraction and only one optic axis, like calcite, two images of the hole are seen. If tbe section be cut perpendicular to tbe axis, two circular holes are seeu drectly superimposed, but at two differeut foci, If the section be in tbe plane of cleaverage, two widely-divided images are visible, the one due to the ordinary ray being circular and the other due to the ordinary ray being distorted and drawn out in two opporite plains at two differeat foci. When the section is cut parallel to tbe axis, this image due to tbe extraordinary ray is still more elongated, but the images are directly superimposed. We tbus at once learn that the mineral bas double refraction, bas an optic axis, and also what is the direction in whicb the section is cut. In tbe case of crystals like Arragonite, wbicb bave two optic axis, there is no ordinary ray, and at the fucal points we see tbe circular bole is drawn out in opposite planes into crosses. The cbaracter of these crosses depends upon the direction of the section, but tbe fact of the crosses being seen at once proves the mineral bas two optic axis. Some facts are better observed if, instead of a circular bole, we examine through the crystalline plate a grating witb two systems of lines at right angles to one another. We then obtain what tbe author calls unifocal or bifocal images, according to the system of crystallization. Crystals with donble refaction bave only one unifocal image; crystals having one optic axis have one unifocal aud bifocal image; whereas crystals having two optic axis give two bifocal images. The definition of unifocal is independent of the position of the lines; whereas in the case of bifocalimages the lines are distinctly visible only when they are parallel or perpendicular to a particular axis of tbe crystal and, spread out, become ohscure and disappear when rotated to a different azimutb, Tbe above-named general characters differ so much in different minerals that they furnish a most valuable means for their identification. J Tue Equation or Erxor.—Tbe Iron Age notes that by numerous experiments it has been proved that one who observes and records an occurrence always gives a result which differs from the exact truth. Even where the observer has heen trained and skilled in ohserving events like those in the most accurate experiments, the rule is tbesame. He records tbe time too early or too late. The error appears in each experiment, aud always to tbe same amount. If the record was too late in one, it invariably was too Iste. This babitnal difference between the time as noted by an observer and the actual time of tbe bappening of the occurrence is what has beeu termed the absolute persoual equation of tbat observer, It represents the amount of error which he will always make. It has been found to differ with different persons for the same class of events. It also differs in the ssme persons for events of different classes. The time required to observo and record the happening of a sudden and unexpected spark, for instance, is always greater than that required in the ease of the expected appearance of a lettor or figure thrown upon a screen. The equation also differs according as tbo faets are observed by the use of one of the senses or snother. The time required for some of the seuses to eonvey intelligence to ns is far greater than that required by others. Foop anp Resrrrarion.—The Chemical News gives an outline of some researehes on the eonsumption of oxygen and the excretion of carbonic acid in man, by Dr. Speck. The author has exsmined the cbanges produced in the respiratory process by the use of fatty food, of coffee, uinine, aleobol and water, and by the inspiration of air respectively rich in carhonie acid, poor in oxygen, and rich in oxygen. His chief conclusions are: Ist. With au increased proportiou of hydrogen in diet the amount of tbe air inspired and expired decreases. Nutriments, such as sugar, which contain little bydrogen in comparison with their oxygen, inyolve more exertion of the respiratory organs than such as are rich in hydrogen, like the fats. 2d. The more carhon predominates in the food ‘in proportion to hydrogen tbe more air is exhaled in proportion to tbat inbaled. 3d. The more carbon increases in the diet in proportion to hydrogen, the more carhonic acid is evolved and the more oxygen is taken up; the riober the diet in hydrogen tbe less oxygen is required. An atmospbere containing five or six per cent. of carbonic acid could he breathed for some minutes without oppression. At 11.5] per cent. great exertion was needed to breathe for one minute. At 7.2 per cent. all tbe carbonic acid produced in tbe hody is retained in tbe blood, and 11.2 per cent. a great part of that also which is inhaled. Tron on Bone,—We read tbat tbe town of Hazleton, Pa., has been excited during the past few days by what was, and by some is still, supposed to he portions of a gigantic fossil skeleton of some hitherto unknown monster. A piece shown to Prof. Leslie was decided by that gentleman to be iron ore. Notwithstanding the opinion of so high an authority, there are some who still contend that a veritable skeleton has been discovered. The formation of the picces tbat have been preserved are certainly very peculiar, one piece in particular bearing a very striking resemhlance to vertebra, showing joints and protuberances at regular distances, and unlike the most fantastic geological formation ever seen, As Prof. Leslie was ohliged to form his opinion from a single piece that had been sent him for examination, it was determined to bave the largest and most peculiar parts suhjected to a further test. Accordingly, Prof, Prime, of Lafayette college, examined the supposed fossil remains. He was wable to decide what they were, and by bis advice they were sent to Philadelphia for the inspection of Prof, Leidy. IncompustIBLe WritING Parer.—Twwo Spanish gentlemen, of Salamanca, have just obtained a patent in Spain for making writing paper incombustible. A number of experiments bave been made with the process, and the results are said to bave been very satisfactory. The paper will not hurn, no matter what may he the intensity of tbe beat applied. A singlesbeet submitted to the direct action of a flame will carhonize, but does not take fire. If a roll of prepared paper is placed inthe bottest fire the outside leaves will carbouize and the edges for a short depth, but tbe interior remains unaltered, the writing or printing being perfectly legible. Its cheapness especially recommends it for public documents, archives, ete., whicb migbt be desirahle to preserve. Papers already written or printed upon may undergo tbe process without injury. The patentees expect to make an arrangement witb tbe government to apply tbe process in the manufacture of tbe paper used by it for public business, which can be done at a very trifling expense. Notes on Puanrs.—The scientific writer for the Independent recently noted a remark of Nature tbat a variety ‘‘under cultivation” was no guide, and took occasion to say that ‘‘cultivation” in tbe discussion of these biological questions had little meaning. Since tbat remark tbe distinguished morphologist, Dr. Maxwell T. Masters, has publisbed a paper on variations in primroses, in wbicb he says that “cultivation” is not the cause of variation in this well-known genus, as be finds variations common among them in a wild state. This, we believe, is the experience of any botanist in any family, as well as in primroses, A singular rbytbmical motion has been discovered by Rodier, of Bordeaux, in a water-plant (Ceratophyllum demersum), The axis curves to one side and to the otber every four bours. It was clearly ascertained that light made no difference in the act. Last year similar motion was noticed in Ziatris, in our own country, and it may he more common in plants than is generally supposed.

Soe” Bee ea as Se ons ee ET ae ae ee A YS _ ceptible of otber applications. October 27, 1877.] MINING AND SCIENTIFIC PRESS 259 — = == : Koy WecHanicat ‘PRocress. The Cause of Blisters on Steel In tho process of making steel, whieh is so largely practised at Shetlield, bars of iron, usually of Swedish of Russian manufacture, are imbedded in chareoal powder, and kept heated to bright reduess during about a week or ten days, aceording to the degree of carbnrization desired. Carbon is therchy imparted to the iron, and ateelis tho product. The bars operated upon aro generally abont threo inelics broad and tlireefourtha of an inch thick. Ifow the carbon finds its way even to the eenter of such bars, is a questiou not yet satisfactorily solved, though it possesses high scientifie interest, and has been mueh discussed. At tho late mevting of the English Iron and Steel Instituto, a paper was real by Dr. Percy, the object of which was to communicate to tho Institute experimental evidenees as to the cause of the siugular phenom. enon which accompanies this process of convertiug iron into steel, viz., tho ovcureneo of blisterlike protuberances on the surfaces of the bars. This appearance is so characteristic and so constant, that the name of “‘blister-stcel” is applied to such bars. The protuberances are hellos, exactly like blisters, aud vary much, hoth in numbor and size; some are not larger than peas, whilo otbers may exceed au incb in dismeter, and they are always confined to the surface of tho bars, for there is a specimen of ‘‘blistersteel” in Dr. Percy’s collection, in which tbore is asingle blister as large as a small hen’s egg, protruding equally from each of tbe opposite surfaces of the har. Dr. Percy concluded that it had been conclusively proved that all bar iron manufactured by eharconl finery processes, or by puddling, must contain, intermixed, some of tbo slag, which results from tbe conversion of Pig-iron into malleable iron hy such processes, in which, let it be remembered, the malleabe iron is never actually melted. On a visit to the great steel works of Messrs. Firtb, at Sbeffield, in February last, Mr. Chas. Hi. Firth undertook at Dr. Percy’s suggestion, to settle the question whither hlistering would occur in the converting process in the case of a bar of iron which had heen actually melted and so freed from all intermixture of ferrous silicate or mnagnetic oxide of iron. The experiment, says Dr. Percy, ‘‘was accordingly made, and with good effect, of confirming, and, I think I might almost say, estahlishing the correctness of the explanation which I ventured to submit concerning tho cause of the formation of the blisters. On the 9th of last May, Mr. Firth informed me that be had melted Swedish bar iron, and cast it into a flat ingot, which be bad carburized in the converting furnace in the usual manuer; and, at the same time, he forwarded to me a piece broken from the ingot after conversion; this piece was about six inches long, three inebes hroad, and a little more than half an inch thick; it showed a fracture at each end, characteristic of converted steel, but there was not the sligbtest indication of a blister.” METHOD OF SHRINKING on TirEs.—The beating of tires by means of hot water instead of by direct contact with fire is brought forward tbrougb Englisb sonrces. It has thus far been applied to railroad work, but possibly it is susThe record of tbe late experiments is as follows: Tbe expansion of tires by bot water, though not elaimed to be new, is believed by tbe anthor to be much superior to the ordinary method of using fire. As applied on the Moscow-Nijni railway, an iron tank, one-fourth filled witb water, is fixed near a stationary boiler, a steam pipe from which is led tbrough it, capable of heating the water to 212° Fahr. Into this tbe tire is plunged by means of a portable crane, and after an immersion of from 10 to 15 minutes, is taken out and immediately placed on the wheel. Three men only are employed, who will fix from 12 to 14 tires in a day of 11 bours. The allowance for sbrinking (the difference between the diameter of the skeleton and that of the tire) is 0.75 millimeter to a meter. This is ascertained by gauges of great accuracy, and, if deviated from, tbe tire wall be either loose after cooling or too small to get on the wheel. When fire is used, the tire can never be heated equally or cooled equally in all parts, and, in consequence is sure to he more or less oval in form, which is not tbe case in bot water. Tbe above railway made a comparison between the two, tbe results of which are given. It appears that, during a six years’ trial of fire-shrunken tires, 37% ran loose and 5% were broken; while, during a three-years’ trial of water-shrunken tires, less than 1% ran loose and only a single tire was broken, The liability to breakage in the former (produced by the irregularity in form) is much insisted on by tbe author as being, of eourse, far more dangerous and costly than the mere loosening of the tire. River Bep Minixc.—About 50 ancbors and an immense quantity of chain were raised from the hed of the St. Lawrence river, Quebec, recently. This nest of iron was the accumulation of years, and took the lifting barge about a month to effect the raising. Export Trade in American Manufactures. There receutly assembled in Philadelphia a body of men couneeted witb our mauufacturing interests, forming “‘s convention of the asso. eiated industries of the United States.” We kuow nothing of the association, except that the Western Manufacturer speaks in favor of it. We read that it devoted timo te devising ways and means for practically relieving our overcrowded markets, and paving tho way for a large production, and thus providing for tho employment of the bhoil santa of workingmen now idle, and sufferiug all the hardships of sueh a condition, A committeo was appoiuted to make investigatious in regard to foreign markete with a view to increasing our export trado, to place samples of American mauuinctures in all foreign markets, aud demonstrate their superiority over those of other nations, and also to learn and report the special kind and quslity of goods most in demand amoug nations with whom we have heretofore had little or uo trnde. This eommittce in a report already submitted, say: “Enough has already‘been dono to justify the present reference to it, and to show the need of some precautious, In the few months ofthe present year, the direct export of Philadelphia inanufactures in new articles, not sent in any quantity previously, is about two millions of dollars in value, and tbe indirect export hy way of New York\ much greater, so many being sent there for sbipment.” Among tbe classes of manufactures in which an export trade has been established, may be mentioned “‘wood-working machinery, bydraulic works, inclnding pumps, the bigher fornis of agricultural implements, house building and bridge building appliances, cotton and woolen machinery, cotton prints, bleached cottons, ginghams, and various forms of colored cottons, cotton mixed goods, worsted goods of various classes, gas meters and gas works, carriages and carriage equipments, leather, ladies’ snd children’s shoes, oil cloths, hats, caps and straw goods, drngs, paints, books, paper and stationery, scales Bea! balances, hardware and tools of every class, lawn mowers, etc.” ArniviciaL Biack Watxut. — A Belgian journal says a new process has been applied to tbe manufacture of artificial black walnut, by which ordinary wood has imparted to it the appearance of the most beautifnl specunens of walnut, adapted to the very finest cahinet work. The wood, first thoroughly dried and warmed, is coated once or twice with a liquid composed of one part by weight of extract of walnut peel, dissolved in six parts of soft water, by heating it to boiling, aud stirring. The wood thus treated is, when half dry, brushed with a solution of one part by weight of hichromate of le in five parts of boiliug water, and, after rying thoronghly, is ruhbed and polished. The color is thus said to be fixed in the wood toa depth of one or two liues, and, in the case of red beech or alder, for instance, the waluut appearance is most perfect. Fioorine Trtes or AsrHatr.—The London Building News states tbat at the Bavarian Industrial Museum may be seen a collection of square tiles of asphalt prepared by a new process, and intended for floorings. The tiles are ornamented with mosaic, in white china or colored glass, which may be arranged according to any design, The drawing to be reproduced is traced on a sheet of thick paper, which is afterward covered with the various fragments of china or glass, which will form the mosaic; a border is made to the sbeet, and boiling aspbalt poured upon it. After the whole is cooled, the paper is taken away with cold water, and the tile is finished. A flooring covered with such tiles hound together by a string of aspbalt appears to have been made bya single melting, and has a good appearance. It indelinitely resists damp, and is consequently useful in bathrooms, halls of houses and balconies. IMPROVEMENTS IN THE CAPITOL AT WASHINGton.—The American Architect says tbat the new ventilating and heating apparatns of the hall of the House of Representatives has proved to be a great success. ‘The new plan was introduced by Edward Clark, arcbitect of the Capitol, in accordance witb the report of the board of United States officers, convened atthe request of the Committee on Public Buildings in the last House. An appropriation of $33,000 was then made. The fresh air is now taken direct from the grounds of the capitol, through the terrace, and is tempered by the warm air in winter from tbe hot water coils, while in summer it is thrown iuto the building direct from the grounds. A series of ventilators to. carry off the foul air bave taken the place of some ornamental pendants in tbe ceiling. Svunsrvrure ror Link Morion.—The master mechanic of the Midland railroad sbops at Norjvich, Conn., is reported to bave invented a substitute for the ‘‘link motion,” which employs but one eccentric, and accomplishes all which that famous method of working valves does without its complication, and with the expenditure of less power. The link motion is in itself so perfect, so simple and so admirably adapted to the uses to which it is put, whether upon the locomotive or mariue engine, tbat it is almost impossihle to eredit the statement in regard to this invention. Although so nearly perfect, the

link motion is still susceptible of very material improvement, and it is quite probable that in time it may be greatly molitiea witb advantage. ra ey BcIENTIFIC P RoGRESS. The Value of Science to Artisans. At tbe annual meeting of the Birmingham and Midland Iustitute, Euglaud, the chairinan, Mr, J. Thackeray Bunce, in the course of his address spoke at some length ou whist wo may term the commercial valuc of seientifie knowledge, or on tho value of thnt kiud of informa. tion to those engaged in manufactures aud industrial pursuits of all kinds. We quote the following emiuently true paragraphs: ‘‘By a study of science at this time, we do not mean study in its highest and best sense, s search after knowledge for its own sake, but that amount of study which is undertaken for the advantago it gives in competition witb other niauufacturers or professionals, and with other uations. Asa nation we must he workers, producers; we csnnot afford to wauder about tbe by-ways of learning for the mere pleasure of gaining knowledge; we must, or the great majority of us must, tread the broad roads already graded and laid out by previous workers, pieking up all the information we can, and storing it . 4 in orderly fashion in our mental wallets for use by snd by. Others among us—a gradually increasing number—will strike out paths for themselves across untrodden fields, and seek for new treasures with more or less success, We cannot all make rescarches and experiments, nor are we all fitted forthe work; but we can all learn sometbing of what is known already, and so prepare ourselves to take advantage of and utilize the discoveries of scientific investigators. Every artisan in the kingdom can, if be will, make himself acquainted with the principles on which the practices with whicb he is familiar are based, aud there is uo industry in the eonntry which would not be benefited by such knowledge on the part of its workers, In a few years now a considerable portion of our workers will be men who are more or less well grounded in theory; they are receiving a technical education, and when they enter the ranks of the industrial army they must, in tbe natural order of things, occupy prominent places. Even now Whitworth’s scholars, at present a comparatively small numher, make their way readily to the frout, and in competition with mere rule-ofthumb men gain an easy victory. Optical Characters of Minerals, A new method of studying characters of minerals was lately described hy Mr. Sorby, F. R. S., in a paper read before the British Association. Theautbor first descrihed the princibles on which the method depended, and that the great difference between the appearance seen with the naked eye and the microscopeis due to the object glass being able to collect divergent rays. Iu looking with alow magnifying power at a small circular hole seen through a section of a crystal, very different phenomena present themselves, according to its optical characters. If double refraction only one well-defined circular hole can be seen. If the mineral possess douhle refraction and only one optic axis, like calcite, two images of the hole are seen. If tbe section be cut perpendicular to tbe axis, two circular holes are seeu drectly superimposed, but at two differeut foci, If the section be in tbe plane of cleaverage, two widely-divided images are visible, the one due to the ordinary ray being circular and the other due to the ordinary ray being distorted and drawn out in two opporite plains at two differeat foci. When the section is cut parallel to tbe axis, this image due to tbe extraordinary ray is still more elongated, but the images are directly superimposed. We tbus at once learn that the mineral bas double refraction, bas an optic axis, and also what is the direction in whicb the section is cut. In tbe case of crystals like Arragonite, wbicb bave two optic axis, there is no ordinary ray, and at the fucal points we see tbe circular bole is drawn out in opposite planes into crosses. The cbaracter of these crosses depends upon the direction of the section, but tbe fact of the crosses being seen at once proves the mineral bas two optic axis. Some facts are better observed if, instead of a circular bole, we examine through the crystalline plate a grating witb two systems of lines at right angles to one another. We then obtain what tbe author calls unifocal or bifocal images, according to the system of crystallization. Crystals with donble refaction bave only one unifocal image; crystals having one optic axis have one unifocal aud bifocal image; whereas crystals having two optic axis give two bifocal images. The definition of unifocal is independent of the position of the lines; whereas in the case of bifocalimages the lines are distinctly visible only when they are parallel or perpendicular to a particular axis of tbe crystal and, spread out, become ohscure and disappear when rotated to a different azimutb, Tbe above-named general characters differ so much in different minerals that they furnish a most valuable means for their identification. J Tue Equation or Erxor.—Tbe Iron Age notes that by numerous experiments it has been proved that one who observes and records an occurrence always gives a result which differs from the exact truth. Even where the observer has heen trained and skilled in ohserving events like those in the most accurate experiments, the rule is tbesame. He records tbe time too early or too late. The error appears in each experiment, aud always to tbe same amount. If the record was too late in one, it invariably was too Iste. This babitnal difference between the time as noted by an observer and the actual time of tbe bappening of the occurrence is what has beeu termed the absolute persoual equation of tbat observer, It represents the amount of error which he will always make. It has been found to differ with different persons for the same class of events. It also differs in the ssme persons for events of different classes. The time required to observo and record the happening of a sudden and unexpected spark, for instance, is always greater than that required in the ease of the expected appearance of a lettor or figure thrown upon a screen. The equation also differs according as tbo faets are observed by the use of one of the senses or snother. The time required for some of the seuses to eonvey intelligence to ns is far greater than that required by others. Foop anp Resrrrarion.—The Chemical News gives an outline of some researehes on the eonsumption of oxygen and the excretion of carbonic acid in man, by Dr. Speck. The author has exsmined the cbanges produced in the respiratory process by the use of fatty food, of coffee, uinine, aleobol and water, and by the inspiration of air respectively rich in carhonie acid, poor in oxygen, and rich in oxygen. His chief conclusions are: Ist. With au increased proportiou of hydrogen in diet the amount of tbe air inspired and expired decreases. Nutriments, such as sugar, which contain little bydrogen in comparison with their oxygen, inyolve more exertion of the respiratory organs than such as are rich in hydrogen, like the fats. 2d. The more carhon predominates in the food ‘in proportion to hydrogen tbe more air is exhaled in proportion to tbat inbaled. 3d. The more carbon increases in the diet in proportion to hydrogen, the more carhonic acid is evolved and the more oxygen is taken up; the riober the diet in hydrogen tbe less oxygen is required. An atmospbere containing five or six per cent. of carbonic acid could he breathed for some minutes without oppression. At 11.5] per cent. great exertion was needed to breathe for one minute. At 7.2 per cent. all tbe carbonic acid produced in tbe hody is retained in tbe blood, and 11.2 per cent. a great part of that also which is inhaled. Tron on Bone,—We read tbat tbe town of Hazleton, Pa., has been excited during the past few days by what was, and by some is still, supposed to he portions of a gigantic fossil skeleton of some hitherto unknown monster. A piece shown to Prof. Leslie was decided by that gentleman to be iron ore. Notwithstanding the opinion of so high an authority, there are some who still contend that a veritable skeleton has been discovered. The formation of the picces tbat have been preserved are certainly very peculiar, one piece in particular bearing a very striking resemhlance to vertebra, showing joints and protuberances at regular distances, and unlike the most fantastic geological formation ever seen, As Prof. Leslie was ohliged to form his opinion from a single piece that had been sent him for examination, it was determined to bave the largest and most peculiar parts suhjected to a further test. Accordingly, Prof, Prime, of Lafayette college, examined the supposed fossil remains. He was wable to decide what they were, and by bis advice they were sent to Philadelphia for the inspection of Prof, Leidy. IncompustIBLe WritING Parer.—Twwo Spanish gentlemen, of Salamanca, have just obtained a patent in Spain for making writing paper incombustible. A number of experiments bave been made with the process, and the results are said to bave been very satisfactory. The paper will not hurn, no matter what may he the intensity of tbe beat applied. A singlesbeet submitted to the direct action of a flame will carhonize, but does not take fire. If a roll of prepared paper is placed inthe bottest fire the outside leaves will carbouize and the edges for a short depth, but tbe interior remains unaltered, the writing or printing being perfectly legible. Its cheapness especially recommends it for public documents, archives, ete., whicb migbt be desirahle to preserve. Papers already written or printed upon may undergo tbe process without injury. The patentees expect to make an arrangement witb tbe government to apply tbe process in the manufacture of tbe paper used by it for public business, which can be done at a very trifling expense. Notes on Puanrs.—The scientific writer for the Independent recently noted a remark of Nature tbat a variety ‘‘under cultivation” was no guide, and took occasion to say that ‘‘cultivation” in tbe discussion of these biological questions had little meaning. Since tbat remark tbe distinguished morphologist, Dr. Maxwell T. Masters, has publisbed a paper on variations in primroses, in wbicb he says that “cultivation” is not the cause of variation in this well-known genus, as be finds variations common among them in a wild state. This, we believe, is the experience of any botanist in any family, as well as in primroses, A singular rbytbmical motion has been discovered by Rodier, of Bordeaux, in a water-plant (Ceratophyllum demersum), The axis curves to one side and to the otber every four bours. It was clearly ascertained that light made no difference in the act. Last year similar motion was noticed in Ziatris, in our own country, and it may he more common in plants than is generally supposed.