formed will yield this present season 100| tons of hay—which is worth on the spot six dollars per ton. A large portion of this 1400 acres is heavily timbered with hard wood, and the soil is generally rich and good for farming purposes. The people of Troy tell me that the land would command on average from 5 to 10 dollars per acre af ter the wood shall have been cut off. Fourth. As it respects the water power of Missisqui river, which you were so anxious to have me examine, I will remark that there is, I am sure as much fall and power as was represented to you. The Missisque river, as I have observed, runs through your lands, and is a deep and rapid stream. The fall in it is so considerable that a number of dams can be thrown across it within the boundaries of your purchase on which many mills might be erected. The dam on which the iron mills, and near which the furnaces should be built is but a short distance from the mine which contains the ore. The river at this place is 150 feet wide and was from four to five feet deep when I was there. By building a dam ten feet high a fall of water of from 14 to 15 fect can be se |—a furnace which would be capable of run-pig iron that should be made, might be car- For preparing the ore for the fur- For the labor of five men 1 50 500 $14 00 The sum of 75 cents for raising a ton of ded in the belief that you will make a profitore and transporting it to the furnace is in-able investment by purchasing the premises deed small, but there are many persons now and working the mines as you have propoin Troy who are ready to contract to do it sed. And before closing this long, and perfor that small compensation. This fact haps tedious letter, I will suggest that shows how advantageously the ore is situ- should iron works be erected on the river ated for mining. At Franconia, and also on near the mine of ore, this spot would doubt. the west side of Lake Champlain, I under-less become the centre of business of the stand that it costs 7 and 8 dollars a ton to mine the ore, so deep in the earth is it inbedded. cured. This spot seems to be formed by town. At present there are two villages in Troy, situated at opposite extremities of the town. As is natural, there exists quite a rivalship between these two places in regard to business. Should the contemplated iron works ever be erected, it is the opinion of the people of Troy, that a new village would spring up near thein, which would becoms the principal village of the town, and would monopolise most of the business which is now transacted in the two present existing villages. But I will draw to a close, for I find I am becoming so much interested in the subject that I may lead you astray, by suggesting what may possibly take place provided you should go on in vour proposed undertaking, and yet I cannot close without expressing the hope that Fifth. In answer to your question whether you will persevere. I hope so, too, more "materials for building dams, mills and furNinth. There is, however, already, a for the public than any private benefit nace and also for smelting iron ore can be large quantity of pig iron used in Vermont, which would result from such an undertaobtained in abundance"-I will state that and I have no doubt but that every pound king. Millions of dollars are now sent out lumber can be obtained from your own pre- that could be made at the contemplated of the country to purchase iron, watch ought mises, and that bricks can be purchased works, would be sold at the furnace for and might be retained in the country, and near by for three dollars per thousand.- forty-five or fifty dollars the ton. For paid to our own citizens for converting into Charcoal, which is an important and necesnow there are many furnaces in the vi-iron the rich ore which now lays dormant sary article in the manufacture of iron, may cinity of the lake, and in the north and useless in our own soil. I hope the be obtained in any quantities in the imme.part of the State which work vast qua ti- ime will soon come when we shall make diate vicinity and at the very low price of ties of pig ron, and many more furnaces al the bar and railroad iron that may be three dollars for the hundred bushels-a would be erected provided the iron should demanded in our country. It is truly mornumber of persons were anxious to con-be made in Troy. The proprietors of the ifying that we should be dependent upon tract to furnish coal at this price. foreign countries for that which our own country can produce in abundance, and at a much less price, even, than it can be manufactured for in those countries. Excuse me from this digression, and believe me that I shall be happy if the contents of this letter shall be acceptable to you. furnaces now in operation, go to Montreal S.xth. To the question "what would it cost to build a damn, erect a furnace-a saw mill-and a power bellows"-I ascertained that a dam might be thrown across the stream at the place above named for 500 I will observe here, that while I was in dollars-and that a saw mill might be built Troy, a committee of gentlemen from St upon it for the like sum-a Mr. Willis Wil. Albans visited Troy, to ascertain if the liams, a mill-wright, offered to contract to iron works were to go into operation; and build both for the sum named-what a pow-in case they were to, they were authorised er bellows would cost I was unable to learn to make an arrangement by which all the Your friend and ob't. serv't. JAMES ANDERSON. P. S. Since the above was written Pig Iron has greatly advanced. POUGHKEEPSIE AND ITS IMPROVEMENTS. The following extract from the Boston Traveller gives but an imperfect idea of the present and prospective manufacturing op erations of Poughkeepsie. PENNSYLVANIA.-BY 8. W. ROBERTS, PRINCIPAL ASSISTANT ENGINEER. The commencement of the construction f the Allegheny Portage Railroad, was auA recent visit to that delightful and flour-Pennsylvania, passed the 21st of March, horised by an act of the Legislature of ishing village, has given us a high opinion 831. Previous to that time, surveys of the of the enterprise and public spirit of many | Allegheny Mountain had been made by sevof its inhabitants. They have laid out new eral eminent engineers; and these surveys Jad thrown much light on the topography streets and public squares, and erected many new and elegant buildings, both for pri- was to pass. of the country through which the Railroad vate and public purposes, which do them Sylvester Welch, Esq. was appointed much credit. The schools and seminaries principal engineer of the work, y the board are of a high order, and their numbers of Canal Commissioners; and he organised are rapidly increasing, which will insure a his locating party, and had the tents pitched near Lilley's Mill, at the head of the mounlarge accession to the population of the ain branch of the Conemaugh, on the 12th place for purposes of education. day of April, 1831. AN ACCOUNT OF THE PORTAGE RAILROAD,|| listance of 10,1 miles. There are five in OVER THE ALLEGHENY MOUNTAIN, IN clined planes on each side of the mountain, arying in inclination from 4° 9′ to 5° 51', or from 725 feet to 10,25 feet elevation, to 100 feet base; they are numbered eastwardly, the one nearest Johnstown being rise or fall of each "level" or grade line, No. 1, that nearest Hallidaysburg, No. 10. The following table shows the length, and and of each inclined plane. The shrewd forecaste of the intelligent and wealthy citizens of Poughkeepsie is The locating party at the beginning, coneer; Solomon W. Roberts, principal assissisted of-Sylvester Welch, principal engitant engineer; Patrick Griffin, surveyor, and evinced, as well in matters of business as The following extract from the Boston Traveller refers to one who would do credit to any age, or country. We shall refer again, and more particularly to Gen. Harvey's operations, as soon as we can find leisure to examine his machines now in operation and in course of construction. The line was commenced at the head of the valley of that stream to Johnstown, a the Little Conemaugh, and continued down distance of 21 miles, where it connects with the western division of the Pennsylvania Canal. The western end of the Railroad was located on the 14th of May. In the month corps as principal assistant engineer, and of May, Mr. W. Milnor Roberts joined the traced the line from the turnpike crossing, near the summit of the mountain, to Lilley's Mill, a distance of five miles. ty-six and two-thirds miles in length, were Rise. 150.00 101.46 feet Length. 4.13 miles 13.06 miles 189.59 1760.43 feet 132.40 1.49 miles 14.50 Level No. 1. from Johnstown to plane No. 1.. "Long level," ascending, 1607.74 feet 1.90 miles 2.56 miles long, at the head and foot of each plane, is A part of the railway, generally 300 feet made exactly level. The planes are all straight in plan and also in profile, excepting that the angles of elevation at the lower ends are rounded off by curves. There are some minor variations in the grades on the "levels," made to suit the ground, which are omitted in the preceding table. From the lengths and heights given above, the average grade of each "level" may be obtained correctly. The grading and masonry of the twentysix miles thus located, were contracted for at Ebensburg, on the 25th of May, and the work was commenced by clearing a track, which consisted of heavy spruce or hemlock 120 feet wide, through the forest,-most of timber. The location of the line from the turnpike crossing, near the summit, at Blair's Gap, eastward to Hallidaysburg, a distance of tea miles and two-thirds, was immediately proceeded with. This part of Poughkeepsie, June, 1833. the work was let to contractors on the 29th "The extensive silk factory, owned by a of July, 1931; and thus the grading and company with a capital of $250,000, is commasonry of the whole Railroad, being thirpleted, and nearly ready to commence operations. Gen. Harvey, a skilful machinist, and the inventor of some half score of "Yankee contrivances," has got up a screw company, with a capital of $200,000, which promises not a little toward the future pros pects of the place. The screws are made by the machinery of Gen. H.'s invention, and with astonishing facility-the whole being accomplished by three rapid applications of the machinery. The first cuts the screw from the wire, and forms the head; the se-opened as a public highway; the State furcond forms the groove and finishes the head; and the third makes the screw, and turns out a highly polished and beautiful article-far superior to the English screws made by hand. It is expected that this establishment will manufacture not less than twenty thousand gross per week, and give steady employment to 300 hands. I saw in the same establishment a machine for coining money, made for the government mint; the model of a saw for felling trees, invented for the express benefit of a "down east" company of speculators; a machine for turning out horse shoes, perfect, with The Portage Railroad consists of eleven branches of the Conemaugh, each of 40 feet only one speedy operation; and a large "levels" or grade lines, and ten inclined span, and one over a branch of the Juniata number of machines for weaving stock planes. The ascent from Johnstown to the at Hallidaysburg, having two arches of 33 frames, were in the "full tide of successful summit is 11715 feet in a distance of feet span, which vary 35 degrees from a operation," all productions of Gen. Harvey's 26,5 miles; and the descent from the sum-right angle with their abutments. There tertile genius.' mit to Hallidaysburg is 1398, feet in a is a tunnel through a spur of the Allegheny On the 18th of March, 1834, the road was The embankments were made 25 feet wide on the top, and the bed of the road in excavations is 25 feet wide, with large side duiches. Where the lines follows the bed of the Conemaugh, it is protected by substantial slope wall. As the railroad is generally constructed along the steep slopes of hills, often of a clayey soil, and as it crosses many small streams, great care in drainage was necessary. Sixty-eight culverts of masonry laid in mortar, the sum of the spans of which is 494 feet, pass under the aishing power on the inclined planes only railroad, besides 85 drains of dry masonry, and it continued in use until the 31st of De- of from 2 to 3 feet span. There are four ceiber, when the navigation of the canals viaducts of hammer-dressed sand-stone, to of Pennsylvania, which this road connects, carry the line over streams. The first and was closed for the season. The Railway largest is over the Conemaugh at the was again opened on the 20th of March, horse shoe bend," about eight miles from 1835; shortly after which, the scond track Johnstown. This magnificent viaduet has of edge rails was completed. On the 11th a single semicircular arch of 80 feet span, of May, the State began to furnish the whole and the top of the masonry is 70 feet above motive power, locomotive engines being the surface of the water. The whole cost used on the "long level;" and this continof this work was $54,562 24 cts., and by ued until about the middle of December. building it, a lateral bend of about 2 miles when the canals were closed by ice. FUL ARTS, BEING THE SUBSTANCE OF CHEMISTRY. V. at the head of inclined plane No. 1, about was $118,883 36. The aggregate cost of APPLICATIONS OF CHEMISTRY TO THE USEfour miles from Johastown, near which the all works done and materials furnished un Conemaugh makes a bead of two miles der contracts for the first track of railway and a half. This tunnel is 901 feet long, was $130,716 59 cis. For the second and 20 feet wide by 19 feet high within the track there were imported 16,976 bars of arch. It is arched for 150 feet in length aedge rails, each 18 feet long, which we ghed each end, and the entrances are finished of 1803 tons, 14 ewt. gross, and cost at Philawith ornamental faca les of cut stone. The delphia $37,494 80 cts., or $48 5 cts. per ton. whole cost of the tunnel, including arching. The aggregate cost of all work done, and was $37,498 85 cts. The edge rail-used on materials furnished under contracts for the the Allegheny Portage, are parallel" rails second track of railway was $362,987 05 cts. CARBON, HYDROGEN AND THEIR of rolled iron, weighing about 40 pounds Aggregate cost of work done and materials per lineal yard. They are supported by furnished under contracts for building ten cast iron chairs, which weigh on an aver- stationary engines and machinery at the are about 13 pounds each. The rail is se-inclined planes, houses, sheds, dwelling. cured in every chair by one iron wedge.-houses for enginemen, wells, water-pipes The stone blocks which support the chairs, and ropes, first set, was $151,923 30 cts. contain three and a half cubic feet each. GENERAL STATEMENT OF THE COST OF THE and they are imbedded in broken stone, at PORTAGE RAILROAD. 151,923 30 $472,162 59 37,779 25 21,049 59 41,335 66 $1,634,357 69 COMPOUNDS. 4. MANUFACTURE OF COKE. a distance of three feet from centre to cen- Cost of Grading, 210,724 66 14,857 66 do. do. in tunnel at $1 47. The viaducts and culverts, and the skew. bridge for carrying the turnpike over in. clined plane No. 6, contain 23,368 perches masonry, and their total cost was $116,402 64 cts. For the first track and the Four locomotive engines have been used upon the "long level" but the expenses of them belong to another account. About fifty thousand tons of freight, and this road during the season of 1935. This Twenty thousand pissengers passed over is but a beginning of the vast trade destined to take this route, which was nearly an un. trodden wilderness five years ago. The State of Pennsylvania has reason to be heated, and the excess of hydrogen uniting proud of her public improvements, and the with a part of the carbon, escapes in the Allegheny Portage Railroad is one of the gaseous form; by the formation and eɛmost important links in that great chain cape of gas, the coke is rendered light and which connects Philadelphia with Pitts-porous. The second variety fuses also, hurg. The above statements were derived from official docu ents in the Railroad office at Johnstown, and consequently may be depended upon. Johnstown, January 1, 1836. PRINTING FOR THE BLIND.-We are happy but the quantity of gas formed is not sufficient to render the coke porous, it is therefore compact and massive. The third variety does not fuse, and the escape of the vapor of water reduces the inass to the form of powder. the last that of least value. Coal of the first class increases in volume when it is coked; the other two varinecessary turn-outs, including a double to inform our readers that the British So-eties yield coke in less volume than the track upon the inclined planes, there were eiety for embossing and circulating the au- coal employed. In their uses in the arts, delivered 509,11 stone blocks, each contain-thorised version of the Bible for the use of the first furnishes the most valuable coke; ing 3 cubic feet, cost $27,072 15 cts.; and the blind have received the munificent grant 505,901 feet lineal of 6 by 8 inch timber of 1001. from the British and Foreign Bible 239,397 feet of 10 by 10 inch, and 2342 feet of 12 by 12 inch timber, of white oak and pine, which cost $47,184 50 cts. The work done under the contracts for "laying" railway on the first track, including fur. nishing broken stone, amounted to $135,776 26 cts. All of the iron rails were imported from Great Britain, by Messrs. A. & G. Ralston, Philadelphia, and also a part of the chairs, spikes, and wedges for the first track. The total cost of British iron at Philadelphia imported for the first track, Society "towards printing the Scriptures Coke may be prepared in iron cylinders or retorts, but this is only done when the volatile products are to be collected; this method will therefore be described when we treat of the preparation of gas for illumination. Treated in this way, cannel coal yields about 50 per cent. of coke, and that of Newcastle as much as 80 per cent. When the distillation is performed at a low temperature, the weight of coke is increased, but its volume and porosity are cease. ces. These holes serve for the introduction of tapering spars. The spars of the lowermost layer are passed through the holes in the sides and ends, at right angles to the respective direction of these surfaces, and at the angles where the spars meet each other, vertical spars are set up. The second range of spars is inclined to the sides in such manner as to meet the vertical spars; and the third layer has the same di rection as the first. diminished. It is therefore advantageous, ||ney the coal is piled in a heap, whose ra- the plank, and in the vertical plane of the when the volatile matters are not the prin-dius is about 6 feet greater than the outer upper edge of the sides. Each side is also cipal object, to effect the decomposition of radius of the chimney. This heap is com- pierced with three ranges of holes, having the coal by a sudden and high heat. posed of alternate layers of large and small the same arrangement in quincunx as Preparation. When coal is rich in hy-coal, the lowermost layer being of pieces of those of the ends, and at the same distandrogen, it may be readily coked in heaps he largest size. The surface of the heap is resembling the pits used in preparing char-covered with ashes or refuse coke, and fire coal. The coal must be in pieces having is applied by throwing burning fuel into not less than three or four inches in each he chimney. Wet ashes are kept on hand dimension. The heaps are conical, having to close any cracks which may occur a base 15 feet in diameter, and a height of the cover of the heap. Dense smoke flows about 30 inches. The heap may be best from the chimney, and is followed by a blue covered with straw, on which is laid a flame; as soon as this appears, the top of layer of inoist earth, the straw being so ap- the chimney must be closed by a plate of plied that the earth cannot enter into the cast iron and the combustion will speedily spaces between the pieces of coal. But as the use of straw is expensive, it is more The coal of Pittsburgh, Pa., as far as usual to cover the large coal for about the we can learn, must resemble in quality the The fine coal is prepared by mixing it height of a foot from the ground with smal-coal employed by Wilkinson, for although into a paste with water, by means of a ler pieces, and the outside with coal-dust; far removed in character from anthracite, it hoe. It is then thrown into the case, and the top of the heap is covered with the re has not hitherto been converted into coke well rammed upon the lower range of spars, fuse coke which is left in the form of pow. by the use of the mode first described. We until a bed has been formed to receive the der, in handling that obtained in previous cannot but express our belief that the meth-second range of spars. This latter range operations. The heap being finished, a od of Wilkinson would be found sufficient being placed, more coal is thrown in and few lighted coals are dropped into an open- for the purpose and that by its aid the man- rammed, until the height of the third range ing of six or eight inches in depth left in ufacture of iron from the ores might be in of spars has been reached, and this being the top; the space is then filled up with troduced into that city, which at present introduced, the rest of the case is filled in fragments of coal, and when the combus-receives almost all the pig iron used in its the same manner. tion has fairly commenced, the whole is extensive foundries and forges, from the covered with earth or refuse coke. The opposite side of the Alleghany range of rest of the process is much the same as mountains. that of preparing charcoal, but is easier, as coal when in mass will not continue to burn after the gaseous matter has escaped, unless new surfaces be exposed to air. In order to lessen the expense of the wood employed, the heap may be built in successive portions, each ten or twelve This method has also been introduced, feet in length, and when one portion has with some modifications in Staffordshire, been finished, the planks and spars are where the coal is of better quality. Here removed to enclose and form passages in the coarser coal is placed in contact with a second portion. The spars form coniIn heaps of greater diameter and height the chimney, and the finer at the outside cal passages in the mass, by which air than we have described, the combustion of the heap, the whole being covered with may be admitted during the combustion. would be too slow at first to form a porous ashes or refuse coke, leaving a few open- When the heap has thus been completed coke, and so rapid at the end as to rendering for the admission of air. As soon as and covered with ashes and refuse coke, it difficult to extinguish. Yet so large is the coke is finished, water is poured on the all the wood is removed, and the heap is the quantity of coke which is required in heap to extinguish the combustion. Int on fire by igniting mall heaps of some instances, and particularly in the his way the product of coke is raised from coarse coal upon each of the openings manufacture of iron, that heaps of so small || 40 to 50 per cent. left in the upper surface by withdrawing a size would be attended with inconven- All the methods of which we have spo- the vertical spars. It has been found that ience. The shape of the heap is therefore ken require that the coal should be princi- in pyramidal heaps, about part of changed in such case from a cone to a long pally of that size which is of most value the coal to be coked is required for this prisin. The breadth of this must not ex- for other purposes, namely in coarse frag purpose; but in small conical heaps, ceed 15 feet, nor its height 3 feet, but its ments. Much however of all good coal is where a single vertical spar will suffice length may be unlimited. This prisin reduced to dust in its extraction from the no more than will be used. must be set on fire in the mode we have mines, and in the handling it must under The attention of the workmen must be mentioned at several points on its upper go. This, in most parts of England, is to-directed not only to close the cracks edge. In this way not only may a greater tally lost, and it has even been necessary to which may appear in the cover, but to quantity of coke be prepared at a single burn it in heaps in order to get rid of it.-keep the passages left by the spars open operation, but the time is shortened, the In France, where coal is more scarce, and by means of iron rods. The completion conical heaps requiring three or four days for consequen ly of more value, it has become of the process is known by the cessation their conversion into coke, while the prisms an important object, that none but such re of the flame. Water is then introd ced are finished in 24 hours. fuse coal should be converted into coke, to the lower passages, whose steam in The product is usually about 40 per and the coarser pieces left to be employed passing through the incandescent heap is cent., but some coals, that of Virginia for for other purposes. This object has been decomposed, and furnishes hydrogen instance, yield 50 per cent. If a coal, in successfully accomplished in the neighbor which escapes in flame. The heap is consequence of its containing but little hy-hood of St. Etienne. then covered closely with earth, and left drogen, does not burn freely, it cannot be The heap in which the coal is burnt may until it cools. converted into coke in this way. Such a have the form either of a truncated cone or coal was found in Yorkshire, (England,) in oblong truncated pyramid. The latter association with minerals which would form is the most easily constructed, and render the manufacture of iron profitable. described. A case of plank is formed, havIn order to apply it to this purpose, an ining the desired figure, say a base of 50 or telligent manufacturer (Wilkinson) imagined the application of a chimney, for the purpose of obtaining a more powerful draught. This chimney is conical in form, about a yard in height, and as much diameter at botton; the diameter at top is two feet; it is built of brick, the lower courses of which are laid in such manner as to leave openings. Around this chim 60 feet in length by 4 feet in breadth, a The planks which form the ends of the In this way coal which would other. wise be lost, yields 50 per cent. of coke of excellent quality. When coal of the first variety (with the exception of cannel coal) is dis tilled in close vessels it yields from 70 to 80 per cent. of coke, by the combustion of about ten per cent. of coal. As the best of the methods we have yet described vields no more than 50 per cent., and the most common of them no more than 40, there is obviously a very great waste. In the neighborhood of coal mines this is more than compensated by the simplicity und facility of this process. But at Ire. conical with a single opening in the cen- with a series of three necked bottles.From this roof a cone of sheet iron The opposite end of the cylinder to that is suspended by a pulley, and nearly fills where the tube issues is closed by a dish, up the area of the chamber; this cone which has no opening in it. The bones as also an opening in the centre. The are broken to pieces and freed from the fat nterior of the chamber, and the lower by boiling. They are placed in the cylin surface of this cone are covered with ders and kept at a red heat for thirty-six coarse woollen coth or with sheep skins. hours; at the end of this time they are taUpon these the soot settles, and may ken out, and shut up in close vessels to pre. when the combustion is over, be separa-vent combustion, until the charcoal is cold. The charcoal is then stamped into coarse powder, and finally ground between millstones into fine meal. distance from mines a more economic A very fine black is made by treating naces. oil. 6. ANIMAL CHARCOAL. If it is to be used as a paint, it is again ground with water, and then dried in earthen moulds. Another form of animal charcoal which was formerly lost, is that left in the preparation of Prussian blue. this manufacture blood is calcined with potash, and the charcoal is obtained by washing off the alkali. In APPLICATION OF ANIMAL CHARCOAL TO THE DISCHARGE OF VEGETABLE COLORS. The action of charcoal in discharging colors seems to be owing to the same cause as its power of condensing gasses; of one of which it takes up 90 times its own bulk. The action in this case is due to a mechan. ical attraction, and to this we may ascribe its powers of retaining the coloring matter of liquids filtered through it. Animal charcoal, upon this theory, owes its superior effect to its greater degree of division; this minute separation of its parts is evident from the fact, that the actual carbonaceous matter in calcined bones does not exceed AUTHORITY.-DUMAS, Chimic appliquee aux Arts. ten per cent. and is yet sufficient to give History. In the preceding section we its intense black color to the remaining mass have mentioned the original mode in which of phosphate and carbonate of lime. Pits as used in preparing charcoal have ivory-black was prepared. For that me- that obtained in the manufacture of Prusnot been found well adapted to the pre-thod, the calcination of fragments of ivory sian blue the division is still more minute, paration of the charcoal of turf. The in close vessels was substituted, and it was as it is in fact a chemical precipitate from little that has been made of good quality speedily found that an article little inferior the blood employed, it has for this reason was prepared in iron cylinders, but as this was to be obtained from bones. Still, so a still more powerful effect. In conseis too expensive for manufacturing pur long as the sole use to which either was ap-quence of this divisibility a larger surface poses, it appears probable that if it should plicable was in the art of painting, this ob- is provided by which the attraction may be ever be necessary to carbonise turf on a servation was of little value. At the end exerted. large scale it will be done in kilns like of the last century, however, it was discothose described under the head of char-vered that carbon, in any form, had the coal. Metiers. 5. LAMP-BLACK. AUTHORITY-Encycolpedie Methodique-Arts at Lamp.black derives its name from its having been originally obtained by collecting the soot of lamps. This method is still used in some cases. Linen wicks are immersed in linseed oil and lighted; the smoke is received in a copper vessel on which the soot is deposited. What is called ivory black was made at first by receiving the smoke of similar wicks upon plates of ivory. coal. In The liquids which best evince the pow ers of charcoal in discharging colors, are the solution of indigo in sulphuric acid and molasses. The relative powers of different forms of charcoal on these solutions are exhibited in the following table, the power of that obtained from bones, without further preparation being taken as the unit. Indigo. Molasses. property of discharging the colors, taste and At present lamp-black is manufactured ་ 3. 1.00 2.00 1.90 In order to render the above table useful it is to be stated that a given quantity of alcined bones will discolor the solution of one thousandth part of its weight of indigo, |
