THE PROGRESS OF SCIENCE IN MEXICO.

Mexico, the land of so many and such frequent revolutions, and the scene of such intestinal commotions and bitter strife through the whole period of her existence, from the Spanish conquest up to within a few years, is at present happily in a state of comparative peace and quiet; the laws are less disregarded, brigandage is gradually disappearing, more attention is being paid to the protection of life and property, and public education is in a prosperous condition. No greater evidence of this felicitous state of affairs could be afforded than that shown in the display of energy and zeal with which the present administration, aided by the foremost Mexican scientists, is carrying out an extended system of scientific explorations, investigations, and internal improvements; and the progress of which is being recorded in a valuable series of government publications; one of these—the Annals of the Minister of Public Works—being now before us. This volume, the third of the series, begins with an article by the able director of the National Meteorological Observatory, Sr. Mariano Barcena, calling attention, in the first place, to the great national importance, as well as necessity, of a well organized system of meteorological observations; (2) giving a description of the Mexican Observatory, its equipment, the questions it proposes to investigate, and the hours of observation; (3) an explanation, accompanied by charts, of the daily system of registration pursued at the observatory; and, finally, observations on the periodic phenomena of vegetation, and notes on the orography and geology of the valley of Mexico. Sr. A. Anquiano follows with a communication on the "Geographical Position of Chalco," prefacing the results of his labors by an able essay on the "Mexican Method" of determining the latitude of places, a "method" founded on an observation of the stars. It would be interesting to quote from this, but our limited space will not permit. The "Citlaltepetl Commission," consisting of the engineers, Srs. Plowes, Rodriguez, and Vigil, whose patriotic ardor induced the minister to commission them to explore "and be the first to plant the flag of Mexican science on the snow clad peak of Citlaltepetl," render their report of operations during the year 1877 in the form of an exceedingly interesting memoir. They ascertained the peak of the volcano Citlaltepetl (or Orizaba) to be 17,651 feet above the level of the sea, which is 292 feet more than Humboldt made it. After a somewhat exhaustive treatise on the "Telescope and its Amplifying Power," by Sr. Jimenez, we have a long and extremely interesting account of the Ancient Aqueduct of Zempoala, one of the most notable of existing monuments of the old Spanish rule. These aqueducts (for there were three) were projected and carried to a successful termination by an humble and ignorant Franciscan monk—the Friar Tembleque. The construction of these remarkable works, begun in 1554 and occupying a period of 17 years, was undertaken for the purpose of carrying water from Zempoala to Otumba (a distance of 27 miles), and was the occasion of a curious contract between the inhabitants of these two cities. It seems that Otumba, situated at a high elevation, needed water; Zempoala was blessed with water, but was sadly in need of spiritual advisers; the people of the former city, therefore, agreed to furnish a certain proportion of friars to minister to the religious wants of the parties of the second part, and the latter in return bound themselves to furnish water, and the labor and materials for the building of an aqueduct to lead it, to the parties of the first part. No tradition remains to state when these structures ceased to be used. The longest of the three extends across the valley of the Papelote, a distance of 2,960 feet, and consists of 68 arches, the highest of which has an altitude of 106 feet. Señor Salazar urges on the Minister of Public Works the importance of having these monuments of a past age repaired and restored, not alone for archaeological reasons, but because Otumba to-day is as greatly in need of running water as it was in that remote period when these viaducts were constructed. Señor Barcena follows with a description and colored plate of a plant (Gaudichaudia Enrico-Martinezii) new to the Mexican flora, and Sr. Federico Weidner with some "General Reflections on the Iron Industry of the Country." Succeeding the latter paper, an exhaustive article by the same writer gives us, from a geological point of view, the structure, as far as can be ascertained, of the "Cerro de Mercado" of Durango, which is said to be one vast mass of iron. The author after a thorough examination of this hill, last year, concludes that it is of eruptive or volcanic origin. This is contrary to the statements made in most published works, the authors of which probably derived their notions from the views expressed by Humboldt, who was of the opinion that this mass of iron was an immense aerolite. Sr. Weidner, however, concludes that the great traveler never visited the locality in person, but obtained his information from heresay. He shows that the hill is deficient in the chemical constituents of aerolites, namely, iron, nickel, and cobalt, in a native or malleable state; but, on the contrary, is made up in a great measure of crystalline magnetic iron, and various useful oxides of the same metal. By a careful estimate of the quantity of iron contained in that portion only of the Cerro which appears above the surface of the soil, the author obtains as a result the enormous sum of 507,000,000 pounds, and this reduced to a metallic state would yield 250,000,000 pounds of pure iron. The structure of this remarkable hill is made apparent to the reader by means of an excellent geological section, in colors, accompanying the text.

The volume closes with some notes by Sr. Barcena on the "Hydrographic System of the Hacienda of Cienega de Mata, and its application to one of the theories that explain Natural Fountains."

In taking leave of this subject we have to congratulate the Mexican Government not only for the valuable matter contained in its scientific publications, but also for the very excellent style in which the latter are being issued. The general make up of the volume before us leaves little to be desired; the arrangement of the types is extremely tasty, the imprint is clean, sharp, and clear, the paper good, the margins of the pages broad, and the illustrations exceedingly well executed. It is to be sincerely hoped that the present state of peace, which our sister republic is enjoying, will endure for numerous years to come; and that the scientific work begun under such happy auspices may go on uninterruptedly until the whole country shall have been thoroughly explored. For as yet, we know but comparatively little about the geology of Mexico, and a great deal is yet to be learned, too, about her natural productions.

Alum in Bread.—A Reply to Dr. Mott's Article in Scientific American of November 16, entitled "Deleterious Use of Alum in Baking Powder."

by w. p. clotworthy, baltimore, md.

On August 13, 1878, I obtained letters patent for the exclusive right to use exsiccated ammonia alum in baking powders. This fact I state that the public may know the reason that elicits this reply to the remarkable article on adulterations in baking powders, in the Scientific American of Nov. 16th, emanating from the pen of Henry A. Mott, Jr. I wish the Professor had been equally candid in stating his reasons for contributing the article. It is rare for a chemist to turn philanthropist without some consideration. The analysis of forty-two baking powders requires no little labor; twenty-one were examined at the expense of the government for the benefit of the Indian Department, the others, no doubt, at the expense and for the benefit of the Royal Baking Powder Company. I hope his services have been liberally requited. The public certainly owe him nothing for his labor or opinions. An excuse can be made for the prejudice existing against the use of alum in any form for baking purposes; it is an inheritance from a preceding age; but no apology can be offered for a practical chemist in this day, who labors to keep alive and foster a prejudice by the suppression of truths and facts. Professor Mott, in attempting to prove a fraud in food, has perpetrated a fraud in facts. That this opinion may not be unwarranted, I will state the facts about alum, which may be new to the public, but familiar to every chemist. Alum was formerly a compound of sulph. alumina and sulph. potash. In the past ten years nearly all manufacturers of alum have substituted sulph. ammonia for the sulph. potash; this change removes from alum a dangerous and objectionable ingredient, and adds a healthful one. Professor Mott recommends the use of ammonia in the form of a carbonate—carbonate of ammonia is one of the results in baking powder of the decomposition which takes place between alum and bicarbonate of soda; in the complete decomposition which takes place pure alumina is eliminated, highly recommended as an antacid. During the process of baking, alum is completely decomposed through the liberation of carbonic acid. Professor Mott must have known this, yet with this knowledge warns the public on the deleterious effect of alum in bread.

About the first of last October I determined to vindicate the use of exsiccated ammonia alum as a substitute for cream of tartar, and accordingly issued a circular to the trade; from this circular I now give the following extract, which enters minutely into the subject:

"To claim that an experience of 35 years in compounding medicines should entitle my opinion on chemicals and chemical compounds to a respectful consideration, is neither presumptuous nor unreasonable. With this simple introduction I now avow myself the originator and patentee of exsiccated ammonia alum baking powder. The use of exsiccated ammonia alum has been declared unhealthful by the advocates of other baking powders, and every manufacturer using it has been held up for public reprobation. This has been done by rival manufacturers, either through ignorance or malice; if from the former they are to be pitied, if from the latter they are contemptible. These opinions have been promulgated by kitchen chemists, whose circle of knowledge begins and ends with cream tartar and soda; and even of these articles they only know that cream tartar is in some way derived from grapes. In this circular I propose to state a few facts in relation to cream tartar and exsiccated alum, and the combinations they form with bicarbonate of soda, and allow you to form your own opinion of their respective merits. Crude tartar is the incrustation found in wine casks. It contains coloring matter and about 15 per cent. of lime. This article is purified and called the cream of tartar, but it is impossible to extract all the lime. Commercially pure cream tartar contains at least 5 per cent. of lime. When cream tartar is used in proportion of two parts to one of bicarbonate of soda, you will have an average of 3 to 4 per cent of lime. In using cream tartar and soda in baking, a chemical change commences as soon as water is added; the cream tartar unites with the soda, setting free the carbonic acid gas, which lightens the bread, and the residue is Rochelle salts. This is what you eat in your bread, the cream tartar and soda entirely disappearing in the process of baking, by forming this salt. Any doctor or chemist will confirm the above statement. When I undertook to manufacture baking powder, I labored to improve the quality and cheapen the cost. The first I accomplished by retaining the carbonic acid until heat was applied, the latter, by manufacturing a more economical acid than foreign cream tartar. After more than a thousand experiments covering a period of six months, I discovered by exsiccating ammonia alum I provided an article that would possess the necessary qualities. This article no more resembles the ordinary alum than charcoal resembles wood—it is light, porous, friable, and without taste. This article, under the influence of heat, combines with the soda and forms Glauber salts. In baking, the alum unites with the soda, just as cream tartar unites. In using the baking powder prepared according to my formula, you have in your bread Glauber instead of Rochelle salts. To your physician apply for his opinion of these salts; I will bow to his decision. Another false impression these zealous guardians of the public health have made is, that I used the exsiccated alum because it was cheap. The fact is that when I commenced its use it cost by the thousand pounds 12 per cent. more than the best cream tartar is worth to-day, and 33 per cent. more than average price of that article for the past year. I have since reduced the cost of manufacturing, and as I did so, correspondingly reduced the price of powder to the public. I regard the quantity of soda in cream tartar baking powders as very objectionable; they generally contain about 33 per cent. In my powder only 20 per cent. The prejudice in the public mind against alum, originated in the habit of the English bakers buying damaged flour, and by the addition of crude alum, made their bread in appearance equal to that made from best flour. Against this practice laws were enacted, not so much against the qualities of alum, as against its use in covering up a fraud in flour. This was the common potash alum and uncombined with any carbonated alkali, and it passed into the stomach unchanged. It is a trick—for it deserves no better name—of our rivals to show by chemical analysis that my powder contains alum, but are careful neither to state the kind nor the change it undergoes in baking. The manufacturer who knowingly misrepresents the goods of a rival, may well be doubted when he speaks of the quality of his own.

"Great stress is laid on the fact that cream tartar is a vegetable acid, the product of the grape, hence it must be healthy. They forget that cream tartar is not entirely vegetable, but principally second handed minerals. It is a compound of tartaric acid, potash, and lime; the last two are minerals, which the grape takes up from the earth, but redeposits them as crude tartar when fermentation converts the grape into wine. In 1807 Sir Humphry Davy from this crude tartar first made the metal potassium. Of lime it is unnecessary to speak. The potash and lime form the bulk of cream tartar. In ammonia alum there is no more mineral substance than in cream tartar. The chemistry of nature is wonderful. Vegetation lives on minerals—wheat, corn, potatoes, are all mineral compounds. Lime, soda, potash, magnesia, sulphur, iron, etc., are all found abundantly in water and grain, and all these minerals are essential in food."

Professor Mott has given the Royal Baking Powder the benefit of his indorsement; it may be all that he claims for it. But baking powders are now judged by constituent ingredients and chemical analysis; to this test I propose to bring the Royal. It is now in the hands of a competent chemist, and when the analysis is complete I will give the public the benefit of a comparison between that powder and the Patapsco. I will take Professor Mott's analysis of Patapsco, which, though not correct, I accept as such. The comparison will be made on the healthfulness of constituents in combination, and the chemical changes they undergo in baking. This is a progressive age. The people want facts, and they will form their own theories. Will the reader believe that in the reign of Henry VIII. of England, a citizen of London was executed for burning coal, which was then a capital offense? A pope about the same time issued a Bull excommunicating all Catholics who used tobacco, calling it the devil's weed. To-day coals still burn, and tobacco solaces millions of the civilized world. If the Royal Baking Powder Company (what a misnomer) possessed royal prerogatives, the advocates of exsiccated alum would fare no better than they did under the sumptuary laws of England. Professor Mott has fulminated ex cathedra his blast, but we survive. "Truth is a torch, the more 'tis shook it shines." Our strength is in the intelligence of the age.

Smith, Hanway & Co., Baltimore.

The College Quarterly says that experiments made at the Iowa Agricultural College show that the popular notion that the trunks of trees elongate is entirely erroneous. Tacks were driven into the trunks of various trees, and the distance between them accurately measured. At the end of the season they were found to have neither increased nor decreased their distances. In the experiment, tree trunks were selected of all ages, from one year up to five or six, and in no case was there any change whatever noticeable.

by berlin h. wright.

Penn Yan, N. Y., Saturday, December 14, 1878. The following calculations are adapted to the latitude of New York city, and are expressed in true or clock time, being for the date given in the caption when not otherwise stated:

PLANETS.

FIRST MAGNITUDE STARS, ETC.

MOON'S PLACE IN THE CONSTELLATIONS AT 7 P.M.

REMARKS.

The sun will attain his greatest southern declination and enter the constellation Sagittarius December 21, 5h. 45m. evening, at which time winter begins. Mars will be 5° north of the moon December 21, in the morning. Saturn will be 90° east of the sun December 18, passing the meridian at 6 o'clock in the evening. He is now advancing among the stars, and will soon be again upon the equinoctial colure. Uranus will be nearly 4° north of the moon December 15.

Under the name of sympathetic inks are designated certain liquids which, being used for writing, leave no visible traces on the paper, but which, through the agency of heat, or by the action of chemicals, are made to appear in various colors. The use of such means for secret correspondence is very ancient. Ovid, Pliny, and other Roman writers speak of an ink of this kind, which, however, was nothing more than fresh milk. It merely sufficed to dust powdered charcoal over the surface of the paper upon which characters had been traced with the colorless fluid, when the black powder adhered only to those places where the fatty matter of the milk had spread. Such a process, however, was merely mechanical, and the results very crude.

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.

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.

A very simple method of reducing nitrate of silver, analogous 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.

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.

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.

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.

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.

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.

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 ⅛ 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.