Scientific American, Vol. XXXIX. No. 6. [New Series.], August 10, 1878, by Various, is part of the HackerNoon Books Series. You can jump to any chapter in this book . NOTES AND QUERIES here NOTES AND QUERIES (1) H. P. says: Please inform me of some recipe for removing superfluous hair. A. Make a strong solution of sulphuret of barium into a paste with powdered starch. Apply immediately after being mixed and allow to remain for ten or fifteen minutes. See also p. 107 (8), vol. 38, and p. 25, current volume. (2) M. A. C. writes: I would like to know how to dissolve bleached shellac, to make it a cement for stone. A. Dissolve it by digestion in 3 or 4 parts of strong alcohol, or by the aid of ¼ its weight of borax in about 4 volumes of boiling water. (3) A. K. asks: 1. In rating substances as to hardness, diamond being No. 10, how do aluminum, osmium, iridium and steel as used in steel pens, number, also common and tempered glass? A. Aluminum about 3, iridosmine 6.5 to 7, steel 5.5 to 6, glass 5 to 5.5. 2. Can glass 1/32 inch in thickness be ground to angles of 15 per cent or less, and points as fine as pins, without difficulty, and how? A. No. (4) D. C. S., asks for a good recipe for cleaning and polishing dirty and tarnished brass. A. Dip for a short time in strong hot aqueous solution of caustic alkali, rinse in water, dip for a few moments in nitric acid diluted with an equal volume of water, rinse again, and finish with whiting. (5) C. J. H. asks for the simplest way of producing a coating of the magnetic or black oxide of iron on iron plates 3 feet x 6 feet. I think it is called the Barff process. A. See pp. 1041 Scientific American Supplement, and 232, vol. 36, and 4, vol. 37, of the Scientific American. How can I make tissue paper impervious to air and water, and yet strong enough to confine gas? A. You may pass the fabric through a solution of about 1 part caoutchouc in 35 parts of carbonic disulphide, exposing it then to the air until the solvent has evaporated. (6) J. H. J. asks how to use hyposulphite (?) of soda to neutralize chloride of lime in cotton and linen goods after bleaching the same. A. After washing from it the large excess of the hypochlorite, the fabric is passed slowly through a solution containing about 10 per cent of the hyposulphite, and then again thoroughly washed in clean water. (7) Columbus asks for a recipe for making ink to rule faint lines, such as he is now writing on. He wants it to rule unit columns in books. A. Dissolve in a small quantity of warm water 20 parts of Prussian blue by the aid of 3 parts of potassium ferrocyanide, and dilute the solution with thin gum water until the proper degree of color is obtained. (8) A. I. B. asks: Can I add anything to Arnold's writing fluid which will cause it to give a good free copy in my letter book? A. Try a little sugar. (9) R. & C. ask for information in regard to the process of printing copies of drawings made on transparent materials, by using chemically prepared paper and exposing to the sunlight. A. It is based on the fact that an acid in the presence of potassium dichromate strikes a blackish-green color when brought in contact with aniline. The paper is prepared by floating it on a bath of aqueous solution of potassium dichromate and a trace of phosphoric acid, and then drying it in the dark. Aniline is dissolved in a little alcohol, and the mixed vapors allowed to come into contact with the sensitive paper that has been exposed to strong sunlight beneath the drawing, when the portions not changed by the sunlight assume the dark color mentioned. All that is requisite is that the paper or cloth original should be fairly penetrable by the light. A piece of paper sensitized as indicated, a sheet of glass to place over the drawing, and a box in which to place the exposed print to the aniline vapor are the only necessary plant. (10) P. Y. P. writes: 1. To find the number of acres in a farm of valley and hillside land, is it by measuring the general contour of the land, allowing its actual surface, or by measuring and allowing only the imaginary face of the plane of it? A. The latter is the correct method. 2. Can more grain, say rye, be raised on a farm of valley and hillside land, as described above, than on a farm having a flat surface, the area of which is equal to the plane of the former, all other things supposed to be equal? A. No. (11) Inventor asks: 1. Can you tell me of a book on sound boards? A. We do not know of a book especially devoted to the subject. 2. Also the best kind of wood to make them out of? A. Spruce. (12) F. C. A. writes: I wish to construct a bar electro-magnet to go in a cylinder 1 inch in diameter and 1 inch long. 1. What size ought the core to be? What number of wire shall I use, and what number of Léclanché cells shall I use (not to exceed twelve) to obtain the greatest possible attractive power, distance 1/10 of an inch? A. Make the core 3/8 inch, wind it with No. 24 silk covered wire. Use 6 or 8 cells. 2. In the same space, could a horseshoe magnet be used, with a gain of power over the bar magnet? A. A cylindrical magnet, which is substantially the same as a horseshoe, might be substituted with advantage for the bar magnet. (13) W. C. H. writes: In turning a tapering shaft in an engine lathe, will the tool if raised above the centers of the lathe turn the taper true from end to end, , neither concave nor convex, the taper to be made by sliding the tail center the required distance? A. The taper will be concave. i. e. (14) H. E. H. asks how to make lime light. A. The lime light is made by directing the jet of an oxyhydrogen blowpipe against a cylinder of lime. The blowpipe is contrived to take the proper proportion of oxygen and hydrogen gas, and the lime is placed in the reducing focus of the jet. (15) L. F. asks: 1. How many Daniell's or Smee's cells would it require to produce the same effect as 50 Bunsen cells? A. About 100. 2. Is the diaphragm equally necessary in Bunsen's, Smee's and Daniell's cells, or can it be omitted in any one of them easier than in the others, and why so? A. The diaphragm or porous cell is required in Daniell's and Bunsen's batteries, but is not used in Smee's. The porous cell is used only in two fluid batteries; its object is to allow the current to pass, but to prevent the mixture of the two liquids. 3. Is the thickness of the zinc of any importance? A. Only that the thicker zinc lasts longer. 4. Which is the cheapest way to produce electric sparks and to charge a Leyden jar, and what will be the expense? A. By means of a frictional electrical machine. The machines cost from $10 upward. (16) R. C. K. writes: I am an engineer by trade; have been at it 9 years. Am out of a position at present and want to learn mechanical draughting. How long would it take me to become a good draughtsman by taking a special course at some university? And with my knowledge of engineering and draughting, would my services be likely to be in fair demand? A. If you are familiar with mechanical operations, you might become a good draughtsman by close application under a competent instructor for one or two years. At present there are many excellent draughtsmen looking for positions. (17) G. B. M. asks for the cause of the ribs or ridges on the surface of a piece of timber which has passed through a planing machine. A. They are frequently due to the intermittent motion of the feed. (18) A. F. writes: Having a small quantity of gold and gold plated things, I would like to know the simplest way to melt it. A. Put it in a small crucible with a little borax and melt in a common kitchen fire. (19) J. H. S., writes: I have three drawings each 21 x 30 inches, which I wish to mount upon cloth like a map, placing them end to end so as to make one whole sheet 90 inches long. The drawings are upon heavy Whatman paper. A. You should stretch wet canvas or factory cloth upon a frame, and while it is still damp apply paste to the backs of the drawings and lay them smoothly on the stretched cloth. When the paste becomes thoroughly dry cut the cloth from the stretching frame and paste a tape binding around the edges. (20) P. M. asks: What is the difference between the inner and outer rails of a 10° curve 100 yards in length, gauge 4 feet 8 inches? A. If this 100 yards is measured on the center of the curve, whose radius in feet is R, the length of the inner rail is R - 2-1/3 ———— x 100, R and of the outer rail R + 2-1/3 ———— x 100. R (21) W. B. K. asks how to make a shoe dressing for ladies' shoes. A. Soft water, 1 gallon; extract of logwood, 6 ozs.; dissolve at a temperature of about 120° Fah. Soft water, 1 gallon; borax, 6 ozs.; shellac, 1-1/2 oz.; boil until dissolved. Potassium dichromate, 3/8 oz.; hot water, 1/2 pint; dissolve, and add all together. It is preferred to add 3 ozs. of strong aqua ammonia to the liquid before bottling. (22) J. D. asks: What chemicals can be put into water to increase its efficiency in extinguishing fire? A. Carbonic acid; sodium carbonate. (23) H. P. writes: Please give me the advantages and disadvantages of substituting a galvanized iron tube 18 inches in diameter and 20 feet high for a wood tank, 5 feet wide and 6 deep, as a container of water in a dwelling house in the country. Would the narrower body of water keep fresh or sweet longer, etc.? Also the thickness of iron necessary to safety, and the number of gallons of water this tube would hold. A. The advantages are in favor of the wooden tank; zinc lined vessels (galvanized) are unsuitable for reservoirs for potable water. See p. 369, vol. 36, Scientific American. 0.3 inch iron would be stout enough. A pipe of the dimensions specified would contain about 327 gallons when full. (24) F. L. M. asks: 1. What is the process by which wire is given a copper finish? A. Clean the wire by pickling it for a short time in very dilute sulphuric acid and scouring with sand if necessary. Then pass the clean wire through a strong bath of copper sulphate dissolved in water. 2. Can wire be thus finished and also annealed? If so, how? A. The wire should be annealed first. 3. What other finish can be put on iron wire (annealed), and by what process? A. Zinc—by passing the clean wire through molten zinc covered with sal ammoniac; tin—by drawing the wire through a bath of molten tin covered with tallow. Minerals, Etc.—Specimens have been received from the following correspondents, and examined, with the results stated: J. H. McF.—A fine quality of kaolin.—F. C. H.—The floury powder consists chiefly, if not altogether, of calcium carbonate.—C. L. G.—They are all silicious limestones. We cannot judge fairly of their value for building purposes from the powders sent.—D. K.—Ferruginous earth or marl.—A. E.—It is a partially decomposed feldspar. The white powder is for the most part an impure, silicious, kaolin.—E. H.—It consists chiefly of basic carbonate and hydrated oxide of lead—poisonous.—J. B. V.—It is a fair quality of pipe clay—impure silicate of alumina—probably worth about $2 per ton in New York. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Various (2013). Scientific American, Vol. XXXIX. No. 6. [New Series.], August 10, 1878. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/19406/pg19406-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at www.gutenberg.org https://www.gutenberg.org/policy/license.html

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