Part 7

A great number of sympathetic inks may be obtained by means of reactions known to chemistry. For instance, write on paper with a colorless solution of sugar of lead; if the water that is used for the solution be pure, no trace of the writing will remain when it becomes dry. Now hold the paper over a jet of sulphureted hydrogen, and the characters will immediately appear on the paper, of an intense black color. The following recipes for inks of this kind are more simple: If writing be executed with a dilute solution of sulphate of iron, the invisible characters will appear of a beautiful blue, if the dry paper be brushed over with a pencil full of a solution of yellow prussiate of potash; or they will be black, if a solution of tannin be substituted for the prussiate. If the characters be written with a solution of sulphate of copper, they will at once turn blue on exposing to the vapors of ammonia. Another sympathetic ink is afforded by chloride of gold, which becomes of a reddish purple when acted upon by a salt of tin. A red sympathetic ink may be made in the following manner: Write with a very dilute solution of perchloride of iron--so dilute, indeed, that the writing will be invisible when dry. By holding the paper in the vapor arising from a long-necked glass flask containing sulphuric acid and a few drops of a solution of sulpho-cyanide of potassium, the characters will appear of a blood-red color, which will again disappear on submitting them to the vapors of caustic ammonia. This experiment can be repeated _ad infinitum_.

During the war in India, some years ago, important correspondence was carried on by the English by means of the use of rice water as a writing fluid. On the application of iodine the dispatches immediately appeared in blue characters.

Sympathetic inks which are developed under the influence of heat only are much easier to use than the foregoing. The liquids which possess such a property are very numerous. Almost every one perhaps knows that if writing be executed on paper with a clean quill pen dipped in onion or turnip juice, it becomes absolutely invisible when dry; and that when the paper is heated the writing at once makes its appearance in characters of a brown color. All albuminoid, mucilaginous, and saccharine vegetable juices make excellent sympathetic inks; we may cite, as among the best, the juices of lemon, orange, apple, and pear. A dilute solution of chloride of copper used for writing is invisible until the paper is heated, when the letters are seen of a beautiful yellow, disappearing again when the heat that developed them is removed. The salts of cobalt, as the acetate, nitrate, sulphate, and chloride, possess a like property. When a dilute solution of these salts is used as an ink, the writing, although invisible when dry, becomes blue when exposed to heat. The addition of chloride of iron, or of a salt of nickel, renders them green, and this opens the way for a very pretty experiment: If a winter landscape be drawn in India ink, and the sky be painted with a wash of cobalt alone, and the branches of the trees be clothed with leaves executed with a mixture of cobalt and nickel, and the snow-clad earth be washed over with the same mixture, a magic transformation at once takes place on the application of heat, the winter landscape changing to a summer scene.

There is a well known proprietary article sold in Paris under the name of _"Encre pour les Dames"_ (ink for ladies). Hager, in a recent scientific journal, states that this consists of an aqueous solution of iodide of starch, and is "specially intended for love letters." In four weeks characters written with it disappear, preventing all abuse of letters, and doing away with all documentary evidence of any kind in the hands of the recipient. The signers of bills of exchange who use this ink are of course freed from all obligations in the same length of time.

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NEW WIRE CLOTHING FOR BURRING CYLINDERS.

Heretofore two kinds of clothing for cylinders for treating fibrous material have been employed, one consisting of a set of serrated rings cut from sheet steel and secured to the periphery of the cylinder, and the other consisting of flat serrated iron wire. The serrated rings, of necessity, entail a great loss of material in their manufacture, and the iron wire clothing is so soft that it soon wears out or becomes dull, necessitating the reclothing or sharpening of the cylinder.

Our engraving represents a new form of steel wire clothing for such cylinders, which was recently patented by Mr. Frank P. Pendleton, of Philadelphia, Pa.

The improvement consists in notching or nicking the base of the teeth or back of the wire, so as to admit of bending the wire around the cylinders without breaking.

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PETROLEUM AND GOLD.

As one of the leading staples of American export, our petroleum wells have been more valuable than gold mines. A recent discovery by Mr. John Turnbridge, of Newark, N. J., indicates that in some cases petroleum wells may be in fact, as well as in effect, real gold mines. He says that while investigating the peculiar behavior of the hydrocarbons and their singular quality of separating the precious metals from aqueous solutions, assisted by constant application that furnished evidence of the force of chemical action which could be satisfactorily measured, there occurred to him the probability that analogous effects might be traced in the operations of nature; more particularly in certain geological formations peculiar to auriferous soils. These ideas, he asserts, have been singularly verified in subsequent research by the discovery of gold in many samples of crude petroleum, also in the sediment or refuse of the distillation of that substance. The attraction existing between the hydrocarbons and many elementary bodies ought to create no surprise, especially if reference is had to the reducing action of the hydrocarbons in contact with metallic solutions. The procedure in the examples above referred to consist in pouring crude petroleum on vegetable fiber or wood shavings and firing it, collecting the ashes and making the usual fire assay. The cupel disclosed a small pellet. After due examination with the appropriate test it was found to be pure gold. The distillery refuse when assayed gave $34.85 value per ton. It may be mentioned in the last case considerable molybdenum was present, a substance resembling plumbago. Mr. Turnbridge has no knowledge of the locality whence these samples of crude petroleum were originally obtained. He infers, however, that oil wells in the vicinity of auriferous deposits may yield a larger quantity of gold than from oil wells situated in carboniferous strata. There has been, he states, a practical application of this discovery for the recovery of gold, applied in cases where quicksilver has failed to be of service.

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REDUCTION OF NITRATE OF SILVER BY MEANS OF CHARCOAL.

A very simple method of reducing nitrate of silver, analagous to that some years ago mentioned by the late Mr. Hadow, is given in the _Archiv der Pharmacie_, by Mr. C. F. Chandler. If crystallized or fused nitrate of silver be placed upon glowing charcoal, combustion forthwith takes place, the silver remaining behind in a metallic form, while nitrous oxide and carbonic acid are freely given off. The nitrate of silver is fused by the heat developed by the reaction, and is imbibed through the pores of the charcoal; as every atom of consumed carbon is replaced by an atom of metallic silver, the original form and structure of the charcoal are preserved intact in pure silver. By proceeding in this manner it is possible to produce silver structures of any desired size, possessing in every way the original form of the wood. A crystal of nitrate of silver is in the first place put upon a piece of charcoal, and a blowpipe flame is then applied in the vicinity, in order to start the reaction in the first instance, and as soon as combustion commences crystal after crystal may be added as these, one after another, become consumed. The silver salt is liquefied, and penetrates into the charcoal, where it becomes reduced. Pieces of silver may in this way be prepared, of one or two ounces in weight, which exhibit all the markings and rings of the original wood to a most perfect and beautiful degree.

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NEW AGRICULTURAL INVENTIONS.

Mr. Charles E. Macarthy, of Forsyth, Ga., has patented an improved Horse Power, designed more particularly to be located beneath a gin house for ginning cotton, but applicable for all purposes for which a horse power is ordinarily employed.

An improved Corn Planter has been patented by Mr. Thomas A. Sammons, of Lewisburg, West Va. This corn planter is designed to plant the corn in straight rows both ways and at varying distances apart. It is constructed upon the general principle of a reciprocating slide, passing alternately beneath a hopper, and carrying a number of grains from beneath the same to a discharge outlet.

An improved machine for Cutting the Bands of Gavels or bundles of grain, and feeding the same to the cylinder of a thrasher, has been patented by Mr. James M. O'Neall, of Fort Worth, Texas.

An improved Sulky Breaking Plow has been patented by Mr. Edward T. Hunter, of Hallsville, Ill. This is an improved sulky attachment for breaking plows, which is so constructed as to receive any ordinary plow; it may be adjusted to cause the plow to work deeper or shallower in the ground, and will allow the plow to be turned to either side.

Mr. Osman C. Du Souchet, of Alexandria, Mo., has invented an improved Check Row Corn Planter and Drill, which is so constructed that its operating mechanism may be at all times under the control of the driver. It will plant the corn in accurate check row, and is easily controlled.

An improved Thrashing Machine has been patented by Mr. Peter Parrott, of Red Bud, Ill. This is an improvement in the class of thrashing machines having an attachment for removing dust from the space in front of the cylinder, and having pickers for loosening or shaking the grain from straw delivered from the cylinder.

An improved Corn Planter has been patented by Mr. John H. Zarley, of Oakland, Ill. The object of this invention is to provide an efficient and cheaply constructed corn planter, which may be drawn forward by horses, but is arranged so that the seed valves may be operated by hand.

Messrs. Clayton M. Van Orman and James M. Hagenbaugh, of Athens, Mich., have patented an improved Grain Separator, in which the arrangement of the screens, feedboard, and blast of a fanning mill effect the thorough removal from the grain of all impurities. Only two screens are employed.

An improved Churning Apparatus has been patented by Messrs. William H. Foster and Isaac C. Roberts, of Louisburg, Kan. It is simple, inexpensive, convenient, and effective in operation. It will bring the butter very quickly, and at the same time gather it.

An improved Plow has been patented by Mr. Robert B. Mitchell, of Minneapolis, Kan. The object of this invention is to improve the construction of sod, stirring, and other plows, so that the cutter may be moved forward as it is worn or ground off. It prevents roots, grass, and other trash from gathering upon the share.

Messrs. John B. Martin and William T. Carothers, of Clarence, Mo., have patented an improved Hay Loader capable of placing hay upon stacks or ricks, or upon wagons. It is simple in its construction and effective in its operation.

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NAPHTHA AND BENZINE.

We have often been asked the difference between benzine and naphtha, many people wanting to know whether naphtha didn't include benzine, or whether it wasn't the same thing under a marketable name. A prominent refiner says that benzine is the first product that arises from the process of refining crude oil, and bears the same relation to naphtha that that distillate does to refined oil. In other words, benzine is crude naphtha. The reason it is not quotable under the name of benzine, therefore, is because it has to be reduced to naphtha before it is marketable in any extensive quantity.

The process that benzine is subject to, to produce naphtha, is not a separate business, but is carried on by the regular oil refiners in the same stills and retorts that the refined oil is produced. The benzine is treated with sulphuric acid, and the result is naphtha, which is in wide demand in Europe, especially in France, for the purpose of producing aniline dyes, while it is also put to many other purposes.

This demand is partially instrumental in keeping up its price, but its rapid evaporation also has a tendency in that direction, as any large seller of it has to take into consideration the depreciation that might take place by the time he sells it on that account, and for the same reason buyers give no more orders than immediate necessity requires.

All refiners, however, do not produce naphtha, but some of them sell the benzine, which is largely used for fuel purposes, for which it is much better than coal, as it is not only absolutely cheaper, but gives a steadier heat.--_Parker Daily_.

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For joining the porcelain heads to the metal spikes used for ornamental nails, the _Prakt. Maschinen Construct._, recommends the use of a thick paste made of a mixture of Portland cement and glue.

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TO INVENTORS.

An experience of more than thirty years, and the preparation of not less than one hundred thousand applications for patents at home and abroad, enable us to understand the laws and practice on both continents, and to possess unequaled facilities for procuring patents everywhere. In addition to our facilities for preparing drawings and specifications quickly, the applicant can rest assured that his case will be filed in the Patent Office without delay. Every application, in which the fees have been paid, is sent complete--including the model--to the Patent Office the same day the papers are signed at our office, or received by mail, so there is no delay in filing the case, a complaint we often hear from other sources. Another advantage to the inventor in securing his patent through the Scientific American Patent Agency, it insures a special notice of the invention in the SCIENTIFIC AMERICAN, which publication often opens negotiations for the sale of the patent or manufacture of the article. A synopsis of the patent laws in foreign countries may be found on another page, and persons contemplating the securing of patents abroad are invited to write to this office for prices, which have been reduced in accordance with the times, and our perfected facilities for conducting the business. Address MUNN & CO., office SCIENTIFIC AMERICAN.

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BUSINESS AND PERSONAL.

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_The Charge for Insertion under this head is One Dollar a line for each insertion; about eight words to a line. Advertisements must be received at publication office as early as Thursday morning to appear in next issue._

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Magic Lanterns and Stereopticons of all prices. Views illustrating every subject for public exhibitions. Profitable business for a man with a small capital. Also lanterns for college and home amusement. 74 page catalogue free. McAllister, Mf. Optician, 49 Nassau St., N. Y.

Chapman Valves and Hydrants received the highest award at Mass. Mechanics Fair. Chapman Valve Manuf. Co., Boston, Mass.

Wanted, cheap.--2d hand Lathe Chuck to swing 17 in. Iron sheave. Penfield Block Works, Lockport, N. Y.

To Manufacturers.--Messrs. Bignall & Ostrander, 806-808 N. 2d St., St. Louis, Mo., have added to their present establishment a Machinery Department, from whence the wants of the Western machine-using public will be supplied. Manufacturers will do well to correspond with them.

On actual test the Eaton Sulky Plow is ahead. Manufacturers wanted to build them. Territory for sale. Address E. C. Eaton, Pinckneyville, Ill.

Sir Henry Halford says Vanity Fair Smoking Tobacco has no equal. Received highest award at Paris, 1878.

Wanted.--Tools for the manufacture of Wagon Axles and Springs. Address Box 66, Lambertville, N. J.

For Sale.--Norwalk Engine, 16 x 42; little used; excellent order; very cheap. Address Box 106, Meriden, Ct.

H. W. Johns' Asbestos Liquid Paints contain no water. They are the best and most economical paints in the world for general purposes, and for wood and iron structures exposed to severe tests of climatic changes, saltwater atmosphere, etc. They are 50 per cent more durable than the best white lead and linseed oil.

1,000 2d hand machines for sale. Send stamp for descriptive price list. Forsaith & Co., Manchester, N. H.

Florey & Smith, San Francisco, make a specialty of introducing useful inventions in the Pacific States.

J. C. Hoadley, Consulting Engineer and Mechanical and Scientific Expert, Lawrence, Mass.

Nickel Plating.--Wenzel's Patent Perforated Carbon Box Anode for holding Grain Nickel. A. C. Wenzel, 114 Center St., New York City.

Bolt Forging Machine & Power Hammers a specialty. Send for circulars. Forsaith & Co., Manchester, N. H.

For Sale.--A 6 x 6 Upright Yacht Engine, 6 H.P. Wm. F. Codd, Nantucket, Mass.

For Solid Wrought Iron Beams, etc., see advertisement. Address Union Iron Mills, Pittsburgh, Pa., for lithograph, etc.

The Lawrence Engine is the best. See ad. page 381.

Sheet Metal Presses, Ferracute Co., Bridgeton, N. J.

The only Engine in the market attached to boiler having cold bearings. F. F. & A. B. Landis, Lancaster, Pa.

Brush Electric Light.--20 lights from one machine. Latest & best light. Telegraph Supply Co., Cleveland, O.

The Lathes, Planers, Drills, and other Tools, new and second-hand, of the Wood & Light Machine Company, Worcester, are to be sold out very low by the George Place Machinery Agency, 121 Chambers St., New York.

For the best advertising at lowest prices in Scientific, Mechanical, and other Newspapers, write to E. N. Freshman & Bros., Advertising Agents, 186 W. 4th St., Cin., O.

For Town and Village use, comb'd Hand Fire Engine & Hose Carriage, $350. Forsaith & Co., Manchester, N. H.

Manufacturers of Improved Goods who desire to build up a lucrative foreign trade, will do well to insert a well displayed advertisement in the SCIENTIFIC AMERICAN Export Edition. This paper has a very large foreign circulation.

Brick Presses for Fire and Red Brick. Factory, 309 S. 5th St., Philadelphia, Pa. S. P. Miller & Son.

Punching Presses, Drop Hammers, and Dies for working Metals, etc. The Stiles & Parker Press Co., Middletown, Conn.

Hydraulic Presses and Jacks, new and second hand. Lathes and Machinery for Polishing and Buffing Metals. E. Lyon & Co., 470 Grand St., N. Y.

Nickel Plating.--A white deposit guaranteed by using our material. Condit, Hanson & Van Winkle, Newark, N. J. English Agency, 18 Caroline St., Birmingham.

H. Prentiss & Co., 14 Dey St., N. Y., Manufs. Taps, Dies, Screw Plates, Reamers, etc. Send for list.

Diamond Engineer, J. Dickinson, 64 Nassau St., N. Y.

Solid Emery Vulcanite Wheels--The Solid Original Emery Wheel--other kinds imitations and inferior. Caution.--Our name is stamped in full on all our best Standard Belting, Packing, and Hose. Buy that only. The best is the cheapest. New York Belting and Packing Company, 37 and 38 Park Row, N. Y.

Presses, Dies, and Tools for working Sheet Metals, etc. Fruit and other Can Tools. Bliss & Williams, Brooklyn, N. Y., and Paris Exposition, 1878.

The Cameron Steam Pump mounted in Phosphor Bronze is an indestructible machine. See advertisement.

Wheel Press, Cotton Press, Pipe Line, and Test Mercury Gauges. T. Shaw, 915 Ridge Ave., Philadelphia, Pa.

The SCIENTIFIC AMERICAN Export Edition is published monthly, about the 15th of each month. Every number comprises most of the plates of the four preceding weekly numbers of the SCIENTIFIC AMERICAN, with other appropriate contents, business announcements etc. It forms a large and splendid periodical of nearly one hundred quarto pages, each number illustrated with about one hundred engravings. It is a complete record of American progress in the arts.

Special Planers for Jointing and Surfacing, Band and Scroll Saws, Universal Wood-workers, etc., manufactured by Bentel, Margedant & Co., Hamilton, Ohio.

Boston Blower Co., Boston, Mass. Blowers, Exhaust Fans, Hot Blast Apparatus. All parts interchangeable material and workmanship warranted the best. Write for particulars.

We make steel castings from ¼ to 10,000 lbs. weight 3 times as strong as cast iron. 12,000 Crank Shafts of this steel now running and proved superior to wrought iron. Circulars and price, list free. Address Chester Steel Castings Co., Evelina St., Philadelphia, Pa.

Machine Cut Brass Gear Wheels for Models, etc. (new list). Models, experimental work, and machine work generally. D. Gilbert & Son, 212 Chester St., Phila., Pa.

Elevators, Freight and Passenger, Shafting, Pulley and Hangers. L. S. Graves & Son, Rochester, N. Y.

Holly System of Water Supply and Fire Protection for Cities and Villages, is fully described in SCIENTIFIC AMERICAN SUPPLEMENT, No. 140.

Howard Patent Safety Elevators. Howard Iron Works Buffalo, N. Y.

Mellen, Williams & Co., 57 Kilby St., Boston, Mass. Wiegand Sectional Steam Boiler. Ætna Rocking Grate Bar.

North's Lathe Dog. 347 N. 4th St., Philadelphia, Pa.

Self-feeding upright Drilling Machine of superior construction. Drills holes from 1/8 to ¾ in. diameter Pratt & Whitney Co., Manufs., Hartford, Conn.

Wm. Sellers & Co., Phila., have introduced a new Injector, worked by a single motion of a lever.

For Shafts, Pulleys, or Hangers, call and see stock kept at 79 Liberty St. Wm. Sellers & Co.

The Turbine Wheel made by Risdon & Co., Mt. Holly N. J., gave the best results at Centennial test.

Wheels and Pinions, heavy and light, remarkably strong and durable. Especially suited for sugar mills and similar work. Pittsburgh Steel Casting Company, Pittsburgh, Pa.

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NOTES AND QUERIES [illus.]

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(1) Detroit asks whether a boat propelled with a force of 3 miles an hour on still water will with the same propelling force run 6 miles an hour in a current running 3 miles an hour? A. We think so.

(2) J. C. R asks: Which was the first railroad built in the United States? That is, a regular, incorporated road, connecting two points, and conveying passengers, freight, etc. A. We believe that the road now known as the Baltimore and Ohio Railroad was the first in the United States chartered for carrying on a general transportation business.

(3) J. R. E. asks how to make an ordinary sunshade for a telescope when placed, and what kind of glass it is composed of. A. Any very dark glass will answer, providing it is perfectly plane. It should be placed between the eye and eyepiece.

(4) W. H. G. S. writes: I wish to give a blue color to screw heads, wire and steel. What shall I use? A. Heat them in a sand bath, or apply shellac or copal varnish, to which a little Prussian blue has been added.