Pectolite, or as it is termed by the miners, "silky spar."--This mineral is quite abundant and in fine masses, not of the great beauty and size of those taken from the Erie Tunnel, but still of great uniqueness. The mineral is recognized by its peculiar appearance, as is shown in Fig. 6, where it may be seen that it is in groups of fine delicate fibers about an inch long, diverging from a point into fan-shaped groups. The fibers are very tightly packed together, as are also the groups; they are very tough individually, and have a hardness of 4, and a specific gravity of about 2.5. It gelatinizes on boiling with acid, and a fragment may be readily fused in the blowpipe flame, yielding a transparent globule. The appearance is the most striking characteristic, and at once distinguishes this mineral from any of the others occurring in this locality. Considerable quantities of pectolite may generally be found on the dump, but also in Shaft No. 1, and especially No. 2. The veins of it are difficult to distinguish from the calcite, as they are almost identical in color, and many of the calcite veins are partly of pectolite--in fact, every third or fourth vein will contain more or less of it. There is, however, a very fine vein of pectolite about twenty-five feet further east from the natrolite bed; it runs from the floor to ceiling, and is about two inches in thickness; some specimens of which I took from these were unusually unique in both size and appearance. It makes a very handsome specimen for the cabinet, and should be carefully trimmed to show the characteristics of the mineral.
Datholite.--This mineral has been found very frequently in the tunnel, it occurring in pockets in the softer trap near the chlorite, and also in the latter, generally at a depth of one hundred and fifty feet from the surface, and consequently near the ceiling of the tunnel. All that has been found of any great beauty has been in the western end of the Shaft No. 1 and the eastern of Shaft No. 2, where the trap is quite soft; here it is found nearly every day in greater or less quantity, and from this some may generally be found on the dump, or, in the vein of chlorite which I mentioned as a locality for the dogtooth spar, considerable may be obtained in it and on its western edge near the ceiling. A ladder about thirteen feet long is used for attending the lights, and may generally be borrowed, and access to the remainder of this pocket thus gained. Datholite is also very characteristic in appearance, and can only be confounded with some forms of calcite occurring near it. It occurs in small glassy, nearly globular crystals; they are generally not over three-sixteenths of an inch in diameter, and generally pure and perfectly transparent, having a hardness of a little over 5, and specific gravity of 3; as it generally occurs as a druse upon the trap, or an apopholite, calcite, etc., this is seldom attainable, however, and we have a very distinctive characteristic in another test: this is the blowpipe, under which it at first intumesces and then fuses to a transparent globule, and the flame, after playing upon it, is of a deep green color. Nitric acid must be used to boil it up with, and with it it may be readily gelatinized. This last test will seldom be necessary, however, and may be dispensed with if the hardness and blowpipe reactions may be ascertained.
Apopholite.--This beautiful mineral has been found in fair abundance at times in Shafts No. 1 and 2 in pockets, and seldom in place, most of it being taken from the loose stone at the mouth of the shaft, and it may generally be found on the dump. It is readily mistaken for calcite by the miners and those unskilled in mineralogy, but a drop of acid will quickly show the difference. The sizes of the crystals are very various, from an eighth of an inch long or thick, to, in one case, an inch and a half. The colors have been varied from white to nearly all tints, including pink, purple, blue, and green; the white variety is, however, the most abundant, and makes a handsome cabinet specimen. The crystals are generally packed together in a mass, but are frequently set apart as heavy druses of crystals having the form shown in Fig. 7. Sometimes, as in the former grouping, the crystals are without the pyramidal terminations, and are then right square prisms. The fracture being at perfect right angles, distinguishes it from calcite. Its hardness is generally fully 5, the specific gravity between 2.4 and 2.5; it is difficult to fuse before the blowpipe, but is finally fused into an opaque globule. Upon heating with nitric acid it partly dissolves, and the remainder becomes flaky and gelatinous. Apopholite, although quite rare, now may be bought from the men, or at least one of the engineers of Shaft No. 2's elevator, and generally at low terms.
Phrenite.--This mineral is quite abundant in Shafts No. 1 and 2, in very small masses, incrustations, and even in small crystals. It occurs embedded in or incrusting the trap, and also with calcite and apopholite. The only sure place to find it is at the southwest side of an opening through the pile of drift rock under the trestle work of the tramway, between shaft No. 1 and the dump, and within a few feet of a number of wooden vats sunk into the ground seen just before descending the hills and near the edge. Here on a number of blocks of trap it may be found, a greenish white incrustation about as thick as a knife blade; it also may be found on the main dump, and is sometimes found in plates one-eighth of an inch thick, of a darker green color, upon calcite. Its easiest distinguishment from the other minerals of this locality, with which it might be confounded, is its great hardness of from 6 to 7. It is very fragile and brittle, however, and is never perfectly transparent, but quite opaque; its specific gravity is 2.9, and it is readily fused before the blowpipe after intumescing. It partly dissolves in acid without gelatinizing, leaving a flaky residue; it is a beautiful mineral when in masses or crystals of a dark green color, but the best place in the vicinity to secure specimens of this kind is, as I will detail hereafter, at Paterson, N. J.
Iron and Copper Pyrites.--Both of these common but frequently beautiful minerals occur in the tunnel and adjacent rocks in great abundance. The crystals are generally about one-fourth of an inch in diameter, and groups of these may be frequently obtained on the dump in the shafts, especially No. 1 and 2, and where the rock is being cleared away for the eastern entrance to the tunnel. They resemble each other very much; the iron pyrites, however, is in cubical forms and having the great hardness of from 6 to 7, while the copper pyrites, less abundant and in forms having triangles for bases, but having sometimes other forms and a hardness of but 3 to 4. Both are similar in aspect to a piece of brass, and cannot be mistaken for any other mineral. The form of the copper pyrites is shown in Fig. 8; the iron is, as before noted, in cubes, more or less modified.
Stilbite.--Small quantities of this beautiful mineral have been found in Shaft No. 2, in a small bed of but a few square feet in area, but quite thick and appearing much like natrolite. This bed was about one hundred feet east from Shaft No. 2, and in the center of the heading when it was at that point. It has been encountered since in small quantities, and it would do well to look out for it in the fresh tunneled portion after the date appended to this paper. It generally occurs in the form shown in Fig. 9, grouped very similarly to natrolite, and being right upon the rock or a thin bed of itself. The crystals are generally half an inch long, but often less. The modifications of the above form, which are frequent in this species, strike one forcibly of the resemblance they bear to a broad stone spear head on a diminutive scale, with a blunted edge; their hardness is about 4, specific gravity 2.2, the color generally a pearly white or grayish. After a long boiling with nitric acid it gelatinizes, but it foams up and fuses to a transparent glass before the blowpipe. A little stilbite may often be found on the dumps.
Laumoniteoccurs in very small quantities on calcite or apopholite, and can hardly be expected to be found on the trip; but as it might be found, I will detail some of its characteristics. Hardness 4, specific gravity 2.3; it generally occurs in small crystals, but more frequently in a crumbly, chalky mass, which it becomes upon exposure to the air. The crystals are generally transparent and frequently tinged yellow in color. It gelatinizes by boiling with acid, and after intumescing before the blowpipe, fuses to a frothy mass. To keep this mineral when in crystals from crumbling upon exposure it may be dipped in a thin mastic varnish or in a gum-arabic solution.
Heulandite.--This rare mineral has been found under the same conditions as laumonite in Shaft No. 2, but it is seldom to be met with, and then in small crystals. It is of a pure white color, sometimes transparent. It intumesces and readily fuses before the blowpipe, and dissolves in acid without gelatinizing. Hardness 4, specific gravity 2.2.
The few other minerals occurring in the tunnel are so extremly rare as not to be met with by any other than an expert, and it is impossible to detail the localities, as they generally occur as minute druses or incrustations upon other minerals with which they may be confounded, and have been removed as soon as discovered. The minerals referred to are analcime, chabazite, Thompsonite, and finally, the mineral which I first found in this formation, Hayesine, which is extremely rare, and of which I only obtained sufficient to cover a square inch. The particulars in regard to its locality, etc., maybe found in theAmerican Journal of Sciencesfor June, page 458. I will now sum up the characteristics of these several minerals of this locality in the table:
-------------------------------------------------------------------------------| | | | | |Name. | H. |Sp.|Action of |Action of |Color.|Appearance.| |Gr.|Blowpipe. |hot acid. | |----------+-----+---+-----------------+-----------------+------+---------------| | | | | |Calcite | 3 |2.6|Infusible, |Soluble with |White |Like Fig.| | |but glows |effervescence | |3 and 4.| | | | | |Natrolite | 5 |2.2|Readily fused |Forms a jelly | do. |Like Fig 5.| | |to clear globule | | || | | | | |Pectolite | 4 |2.5| do. | do. do. | do. |Divergent| | | | | |fibers, Fig. 6.| | | | | |Datholite | 5 |3.0|Intumesces, fused|Forms a jelly |Color-|Small, nearly| | |to clear globule,| |less |spherical, etc.| | |gives green flame| |white || | | | | |Apopholite| 5 |2.5|Difficult, fused |Partly soluble |Tinted|Like Fig. 7.| | |to opaque globule|in nitric acid | || | | | | |Phrenite | 6 |2.9|Intomesces, fused|Partly soluble |Green-|In tables and|to 7 | |to clear globule |in nitric acid, |ish |incrustations.| | | |leaving flakes | || | | | | |Iron | 6 |5.0|Burns and yields | |Brass |Cubical.pyrites |to 7 | |a black globule, | | || | |decrepitates | | || | | | | |Copper | 3 |4.2| do. do. | | do. |Tetrahedronal.pyrites |to 4 | | | | || | | | | |Stilbite | 4 |2.2|Intumesces and |Difficult; jelly |White |Like Fig. 8.| | |fuses readily |on long boiling | || | | |with nitric acid.| || | | | | |Laumonite | 4 |2.3|Intumesces and |Readily | do. |Generally|to 0 | |fuses to frothy |gelatinizes | |chalky.| | |mass | | || | | | | |Heulandite| 4 |2.2|Intumesces and |Soluble, no | do. |In right| | |readily fuses |jelly | |rhomboidal| | | | | |prisms.| | | | | |-------------------------------------------------------------------------------
To Distinguish the Minerals together the one from the other.--Calcite by effervescing on placing a drop of acid upon it. Natrolite resembles stilbite, but may be distinguished by gelatinizing readily with hydrochloric acid and by not intumescing when heated before the blowpipe; from the other minerals by the form of the crystals and their setting, also the locality in the tunnel in which it was found.
Pectolite sometimes resembles some of the others, but may be readily distinguished by itstoughlong fibers, not brittle like natrolite. Datholite may generally be distinguished by the form of its crystals and their glassy appearance, with great hardness, and by tingeing the flame from the blowpipe of a true green color. Apopholite is distinguished from calcite, as noticed under that species, and from the others by its form, difficult fusibility, and part solubility.
Phrenite is characterized by its hardness, greenish color, occurrence, and action of acid. Iron pyrites is always known by its brassy metallic aspect and great hardness. Copper pyrites, by its aspect from the other minerals, and from iron pyrites by its inferior hardness and less gravity.
Stilbite is characterized by its form, difficult gelatinizing, and intumescence before the blowpipe; from natrolite as mentioned under that species.
Laumonite is known by its generally chalky appearance and a probable failure in finding it.
Heulandite is distinguished from stilbite by its crystals and perfect solubility; from apopholite by form of crystals.
In the next part of this paper I will commence with Staten Island.
July 1, 1882. (To be continued.)
The author has endeavored to ascertain what agents are able to destroy the spores of bacilli, how they behave toward the microphytes most easily destroyed, such as the moulds, ferments, and micrococci, and if they suffice at least to arrest the development of these organisms in liquids favorable to their multiplication. His results with phenol, thymol, and salicylic acid have been unfavorable. Sulphurous acid and zinc chloride also failed to destroy all the germs of infection. Chlorine, bromine, and mercuric chloride gave the best results; solutions of mercuric chloride, nitrate, or sulphate diluted to 1 part in 1,000 destroy spores in ten minutes.--R. Koch.
[Footnote: Read January 10th. 1882.]
The question has been asked, "What is the chemically scientific definition of crystallization?" Now as the study of crystallization and its effect upon matter, physically as well as chemically, will be of interest, considering the subject matter for discussion, I shall not only endeavor to answer the question, as I understand it, but try to treat it somewhat technologically.
Having this object in view, I have prepared or brought about the conditions necessary to the formation of a few crystals of various chemical substances, which for various reasons, such as lack of time and bad weather, are not as perfect as could be desired, but will perhaps subserve the purpose for which they were designed. I think you will agree with me that they are beautiful, if they are imperfect, and I can assure you that the pleasure of watching their formation fully repays one for the trouble, if for no other reason than the mere gratification of the senses. From the earliest times and by all races of men, the crystal has been admired and imitated, or improved by cutting and polishing into faces of various substances. I have also procured specimens of steel and iron which show the effect of crystallization, which was produced (perhaps) under known conditions, so that the conclusions which we arrive at from their study will have a fair chance of being logical, at least, and perhaps of some practical value.
When we examine inanimate nature we find two grand divisions of matter,fluidandsolid. These two divisions may be subdivided into, the former gaseous and liquid, the latter amorphous and crystalline; but whether one or the other of these divisions be considered, their ultimate and common division will be the ATOM. By the atom we understand that portion of matter which admits of no further division, which, though as inconceivable for minuteness as space is for extent, has still definite weight, form, and volume; which under favorable circumstances, has that power or force called cohesion, the intensity of which constitutes strength of material, which every engineer is supposed to understand, but which lies far beyond the powers of the human mind for comprehension or analysis. When we apply a magnet to a mass of iron filings, we observe the particles arrange themselves in regular order, having considerable strength in one direction, and very little or none in any other. Now, although we understand very little about the force which holds these particles in position, we do know that it is actual force applied from without and maintained at the expense of some of the known sources of force. But the force or power or property of cohesion seems to be a quality stored within the atom itself, in many cases similar to magnetism, having powerful attraction in some directions and very little or none in others. A crystal of mica, for instance, or gypsum may be divided to any degree of thinness, but is very difficult to even break. This property of crystals is termed cleavage. Cohesion and crystallization are affected variously by various circumstances, such as heat or its absence, motion or its absence, etc. In fact, almost every phenomenon of nature within the range of ordinary temperatures has effects which may be favorable to the crystallization of some substances, and at the same time unfavorable to others; so it will be seen that it is impossible to lay down any rule for it except for named substances, like substances requiring like conditions, to bring its atoms into that state of equilibrium where crystallization can occur. If we examine crystals carefully we find, not only that nature has here provided geometric forms of marvelous beauty and exactness, with faces of polish and quoins of acuteness equal to the work of the most skillful lapidist, "but that in whatever manner or under whatever circumstances a crystal may have been formed, whether in the laboratory of the chemist or the workshop of nature, in the bodies of animals or the tissues of plants, up in the sky or in the depths of the earth, whether so rapidly that we may literally see its growth, or by the slow aggregation of its molecules during perhaps thousands of years, we always find that the arrangement of the faces is subject to fixed and definite laws." We find also that a crystal is always finished and has its form as perfectly developed when it is the minutest point discernible by the microscope as when it has attained its ultimate growth. I might add parenthetically that crystals are sometimes of immense size, one at Milan of quartz being 3 feet 3 inches long and 5 feet 6 inches in circumference, and is estimated to weigh over 800 pounds; and a gigantic beryl at Grafton, N. H., is over 4 feet in length and 32 inches in diameter, and weighs not less than 5,000 pounds; but the most perfect specimens are of small size, as some accident is sure to overtake the larger ones before they acquire their growth, to interfere with their symmetry or transparency. This you will see abundantly illustrated by the examples which I have prepared, as also the constancy of the angles of like faces. Chemically speaking, the crystal is always a perfect chemical body, and can never be a mechanical mixture. This fact has been of great value to the science of chemistry in developing the atomic theory, which has demonstrated that a body can only exist chemically combined when a definite number of atoms of each element is present, and that there is no certainty of such proportions existing except in the crystal. I hold before you a crystal of common alum. Its chemical symbol would be Al2O3,3SO3+KO,SO3+24H2O. If we knew its weight and wished to know its ultimate component parts, we could calculate them more readily than we could acquire that knowledge by any other means. But the elements of this quantity of uncrystallized alum could not be computed. Then we may define crystallization to be the operation of nature wherein the chemical atoms or molecules of a substance have sufficient polarized force to arrange themselves about a central attracting point in definite geometrical forms.
Fresenius defines it thus: "Every operation, or process, whereby bodies are made to pass from the fluid to the solid state, and to assumecertain fixed,mathematically definable, regular forms." It would be folly for me to attempt to criticise Fresenius, but I give you both definitions, and you can take your choice. The definition of Fresenius, however, will not suit our present purpose, because the crystallization of wrought iron occurs, or seems to,afterthe iron has acquired asolid state.
Iron, as you all know, is known to the arts in three forms: cast or crude, steel, and wrought or malleable. Cast iron varies much in chemical composition, being a mixture of iron and carbon chiefly, as constant factors, with which silicium in small quantities (from 1 to 5 per cent.), phosphorus, sulphur, and sometimes manganese (e.g. spiegeleisen) and various other elements are combined. All of these have some effect upon the crystalline structure of the mass, but whatever crystallization takes place occurs at the moment of solidification, or between that and a red heat, and varies much, according to the time occupied in cooling, as to its composition. My own experience leads me to think that a cast iron having about 3 per cent. of carbon, a small per centage of phosphorus, say about ½ of 1 per cent., and very small quantities of silicium, the less the better, and traces of manganese (the two latter substancesslaggingout almost entirely during the process of remelting for casting), makes a metal best adapted to the general use of the founder. Such proportions will make a soft, even grained, dark gray iron, whose crystals are small and bright, and whose fracture will be uneven and sharp to the touch. The phosphorus in this instance gives the metal liquidity at a low temperature, but does not seem to influence the crystallization to any appreciable extent. The two elements to be avoided by the founder are silicium and sulphur. These give to iron a peculiar crystalline appearance easily recognized by an experienced person. Silicium seems to obliterate the sparkling brilliancy of the crystalline faces of good iron, and replace them with very fine dull ones only discernible with a lens, and the iron breaks more like stoneware than metal, while sulphur in appreciable quantities gives a striated crystalline texture similar to chilled iron, and very brittle. Phosphorus in very large quantities acts similarly. The form of the crystal in cast iron is the octahedron, so that right angles with sharp corners should be avoided as much as possible in castings, as the most likely position for a crystal to take would be with its faces along the line of the angle. Steel, to be of any value as such,mustbe made of the purest material. Phosphorus and sulphurmustnot exist, except in the most minute quantities, or the metal is worthless. If either of these substances be present in a bar of steel, its structure will be coarse, crystalline and weak. The reason of this is unknown, but probably their presence reduces the power of cohesion; and, that being reduced, gives the molecules of steel greater freedom to arrange themselves in conformity with their polarity, and this in its turn again weakens the mass by the tendency of the crystals to cleavage in certain directions. Carbon is a constant element in steel, as it is in cast iron, but is frequently replaced by chromium, titanium, etc., or is said to be, though it is not quite clear to me how it can be so if steel is a chemical compound. However this may be, we know that a piece of good soft steel breaks with a fine crystalline fracture, and the same piece hardened when broken shows either an amorphous structure or one very finely crystalline, which would indicate that the crystals had been broken up by the action of heat, and that they had not had sufficient time to return to their original position on account of the sudden cooling. The tendency of the molecules of steel after hardening to assume their natural position when cold seems to be very great, for we have often seen large pieces of steel burst asunder after hardening, though lying untouched, and sometimes with such force as to hurl the fragments to some distance. If a piece of steel be subjected to a bright yellow or white heat its nature is entirely changed, and the workman says it is burnt. Though this is not actually a fact, it does well enough to express that condition of the metal. Steel cannot be burnt unless some portion of it has been oxidized. The carbon would of course be attacked first, its affinity for oxygen being greatest; but we find nothing wanting in a piece of burnt steel. It can, by careful heating, hammering and hardening, be returned to its former excellence. Then what change has taken place? I should say that two modifications have been made, one physical, the other chemical. The change chemically is that of a chemical compound to a mixture of carbon and iron, so that in a chemical sense it resembles cast iron. The change physically is that of crystallization, being due partly to chemical change and partly to the effect of heat. I have procured a specimen of steel showing beautifully the effect of overheating. The specimen is labeled No. 1, and is a piece of Park Brothers' steel (one of the best brands made in America). It has been heated at one end to proper heat for hardening, and at the other is what is technically called "burnt." It has been broken at intervals of about 1½ inches, showing the transition from amorphous or proper hardening to highly crystalline or "burnt." Malleable or wrought iron is or should be pure iron. Of course in practice it is seldom such, but generally nearly so, being usually 98, 99, or even more per cent. It is exceedingly prone to crystallization, the purer varieties being as much subject to it as others, except those contaminated with phosphorus, which affects it similarly with steel, and makes it very weak to cross and tensile strains. I have never estimated the quantity present in any except one specimen, a bar of 1½ round, which literally fell to pieces when dropped across a block of iron. It had 1.32 per cent. of phosphorus and was very crystalline, though the crystals were not very large. Iron which has been, when first made, quite fibrous, when subjected to a series of shocks for a greater or less period, according to their intensity, when subjected to intense currents of electricity, or when subjected to high temperatures, or has by mechanical force been pushed together, or, as it is called, upset, becomes extremely crystalline. Under all of these circumstances it is subjected to one physical phenomenon, that of motion. It would seem that if a bar of iron were struck, the blow would shake the whole mass, and consequently the relative position of the particles remain unchanged, but this is not the case. When the blow is struck it takes an appreciable length of time for the effect to be communicated to the other end so as to be heard, if the distance is great. This shows that a small force is communicated from particle to particle independently along the whole mass, and that each atom actually moves independently of its neighbor. Then, if there be any attraction at the time tending to arrange it differently, it will conform to it. So much for theory with regard to this important matter. It looks well on paper, but do the facts of the case correspond? If practically demonstrated and systematically executed, experiments fail to corroborate the theory, and if, furthermore, we find there is no necessity for the theory, we naturally conclude that it is all wrong, or, at least, imperfectly understood. Now there is one other quality imparted to iron by successive shocks, which, I think, is independent of crystallization, and this quality is hardness and consequent brittleness. One noticeable feature about this also is, that as "absolute cohesion" or tensile strength diminishes, "relative cohesion" or strength to resist crushing increases. Specimens Nos. 2, 3, and 4 are pieces of Swedish iron, probably from the celebrated mines of Dannemora. Nos. 2 and 3 are parts of the same bolt, which, after some months' use on a "heading machine" in a bolt and nut works, where it was subjected to numerous and violent shocks, (perhaps 50,000 or 60,000 per day), it broke short off, as you see in No 2, showing a highly crystalline fracture. To test whether this structure continued through the bolt, I had it nicked by a blacksmith's cold chisel and broken. The specimen shows that it is still stronger at that point than at the point where it is actually broken, but the resulting fracture shows the same crystalline appearance. I next had specimen No. 4 cut from a fresh bar of iron which had never been used for anything. It also shows a crystalline fracture, indicating that this peculiarity had existed in the iron of both from the beginning.
I next took specimen No. 3 and subjected it to a careful annealing, taking perhaps two hours in the operation. Although it is a 1-1/8 bolt and has V threads cut upon it we were unable to break it, although bent cold through an arc of 90°, and probably would have doubled upon itself if we had had the means to have forced it. Now what does this show? Have the crystals been obliterated by the process of annealing, or has only their cleavage been destroyed, so that when they break, instead of showing brilliant, sparkling faces, they are drawn into a fibrous looking mass? The latter seems to be the most plausible theory, to which I admit objections may be raised. For my own part, I am inclined to the belief that the crystal exists in all iron which is finished above a bright red heat, and that between that and black heat they are formed and have whatever characteristics circumstances may confer upon them, modified by the action of agencies heretofore mentioned.
A catalogue, containing brief notices of many important scientific papers heretofore published in the SUPPLEMENT, may be had gratis at this office.
Terms of Subscription, $5 a Year.
Sent by mail, postage prepaid, to subscribers in any part of the United States or Canada. Six dollars a year, sent, prepaid, to any foreign country.
All the back numbers of THE SUPPLEMENT, from the commencement, January 1, 1876, can be had. Price, 10 cents each.
All the back volumes of THE SUPPLEMENT can likewise be supplied. Two volumes are issued yearly. Price of each volume, $2.50, stitched in paper, or $3.50, bound in stiff covers.
COMBINED RATES--One copy of SCIENTIFIC AMERICAN and one copy of SCIENTIFIC AMERICAN SUPPLEMENT, one year, postpaid, $7.00.
A liberal discount to booksellers, news agents, and canvassers.
MUNN & CO., Publishers,
261 Broadway, New York, N. Y.
In connection with theScientific American, Messrs. MUNN & Co. are Solicitors of American and Foreign Patents, have had 35 years' experience, and now have the largest establishment in the world. Patents are obtained on the best terms.
A special notice is made in theScientific Americanof all Inventions patented through this Agency, with the name and residence of the Patentee. By the immense circulation thus given, public attention is directed to the merits of the new patent, and sales or introduction often easily effected.
Any person who has made a new discovery or invention can ascertain, free of charge, whether a patent can probably be obtained, by writing to MUNN & Co.
We also send free our Hand Book about the Patent Laws, Patents, Caveats. Trade Marks, their costs, and how procured, with hints for procuring advances on inventions. Address
MUNN & CO., 261 Broadway, New York.
Branch Office, cor. F and 7th Sts., Washington, D. C.