T278. Effect of Twist on the Physical Properties of a McGowan, Charles W. Schoffstall, and A. A. Mercier This investigation was made to determine the most suitable twist to use in making the yarn to be used in the Pima post office bag investigation. Data were obtained on the relation of the twist to the breaking strength, diameter of the yarn, yarn count, contraction, and angle of twist. While the data were not sufficiently extensive to attempt to fix definite formula for these relations, it is thought that the tabular and graphical relation studied in this investigation will be useful for the cotton manufacture. The most suitable twist for the yarn to be used in the Pima mail bags was found to be about 12 turns per inch. (Feb. 11, 1925.) 11 pp. Price, 10 cents. T279. Testing of Fire-Clay Brick with Special Reference to Their Use in Coal-Fired Boiler Settings.... ...R. F. Geller Fire-clay brick, representative of the product as manufactured in the United States, were obtained through the cooperation of Stone & Webster, together with a report of a field survey covering the service rendered by fire-clay refractories in boiler settings. The refractories were subjected to heat and load tests in the laboratory, were analyzed chemically, and several were examined petrographically. The data presented in the field survey were correlated and the combined results of laboratory test and service tests were compared. As a result of this work the qualifications of high-grade refractories for coal-fired boiler settings are believed to have been established. (Feb. 13, 1925.) 43 pp. Price, 20 cents. T280. Reclamation of Gasoline Used in Dry Cleaning. ... ....C. C. Hubbard This paper outlines and discusses briefly the processes that have been used for the "purification" and recovery of gasoline used in dry cleaning. Results are reported of laboratory and plant experiments and of large scale plant tests. A "settling and decanting" process is recommended, using activated carbon and an aqueous solution of trisodium phosphate. (Mar. 31, 1925.) 13 pp. Price, 5 cents. T281. Malleability and Metallography of Nickel.... .P. D. Merica and R. G. Waltenberg In the manufacture of rolled, forged, and sand-cast products, of nickel and nickel alloys, rather unusual metallurgical treatments of the molten metal are resorted to in order that the resulting castings may be malleable in the hammer shop or mill. This investigation has shown that the reason for these special treatments lies in the presence in these alloys of a very small amount of sulphur, the detrimental effects of which are eliminated by the treatment of the molten metal with manganese and magnesium. The structural mechanism of the effect of these treatments is demonstrated and the high temperature chemical reactions involved are indicated. This work was done under an industrial fellowship maintained at the Bureau of Standards by The International Nickel Co. (Apr. 2, 1925.) 32 pp. Price, 10 cents. T282. Technology of Cotton Machinery. Part I. Cal culations on Pickers.... .A. A. Mercier Paper consists of calculations on pickers, the machines used in the first processes of cotton manufacturing. The calculations are important because they cover the fundamental data on these machines. These data consist of the r. p. m. of certain moving parts, ratio of one part to another, production resulting when using certain speeds and ratios of speeds, and amount of beating given the cotton. The calculations allow for a wide range of speeds, various size pulleys, and different changes in the weight of the product. They were prepared for the purpose of eliminating waste of time in determining the pulleys and gears to be used to obtain required speeds, drafts, production, and amount of beating, as well as to give information which can not be had without searching through books or by correspondence. By chart or table, organizations are quickly formed and are most valuable where frequent changes are made. (Apr. 2, 1925.) 30 pp. Price, 10 cents. T283. Effect of Tire Resistance on Fuel Consumption... ...W. L. Holt and P. L. Wormeley Technologic Paper No. 240 data were given showing the rolling resistance found in various pneumatic tires. These have been compiled, together with similar tests of balloon tires, to show in a concise form the maximum and minimum resistance which may be expected in various types and sizes of pneumatic tires. The values for tire resistance have been compared with other resistances which the fuel used by an automobile is required to overcome, and conclusions drawn as to what extent the total fuel consumption of an automobile can be influenced by the tires. (Apr. 6, 1925.) 11 pp. Price, 5 cents. T284. A Study of the Seasonal Variation of Radio- .J. L. Preston and E. L. Hall In measurements of radio-frequency properties of laminated phenolic insulating materials, the results of which are published in Bureau of Standards Technologic Paper No. 216, some samples were found to exhibit changes in these properties with time. This led to a more systematic study of a limited number of samples. Incidentally, data on the variation of phase difference with frequency were also secured. From observations made on 13 samples over a period of one year, it was found that the radiofrequency phase difference had a definite seasonal variation. In general, the phase difference returned to its original value after a year's cyclic changes. (Apr. 10, 1925.) 10 pp. Price, 5 cents. T285. Release of Internal Stress in Brass Tubing.. R. J. Anderson and E. G. Fahlman Results are given on the effect of low-temperature heat treatment on the release of stress and on the physical properties of cold-worked leaded brass tubing. The object was to investigate the possibilities of effecting stress release in cold-worked brass tubing by heating at moderate temperatures without accompanying loss in hardness and strength. It is shown that brass tubing which has been reduced in area by cold working in the range 17 to 56 per cent can be heated over a fairly wide time-temperature range without loss in hardness or tensile strength, but with substantially complete release of internal stress. For the material worked with it was found that heating for two to three hours at 325° C. was suitable. (May 14, 1925.) 31 pp. Price, 15 cents. T286. Comparative Durability of Chrome and Vegetable R. C. Bowker and M. N. V. Geib An investigation to determine primarily the comparative wearing qualities of vegetable and chrome tanned sole leathers. Comparative tests were made between vegetable and natural chrome, vegetable and filled chrome, and between natural chrome and filled chrome. Includes a general discussion of the comparative properties of the two leathers, description of the leathers tested, methods used and the results of wear, chemical, and T287. A Hot-Wire Anemometer for Measuring Air Flow through Engine Radiators.. Carl G. F. Zobel and L. B. Carroll In connection with various tests on airplane radiators, a portable instrument for the rapid measurement of average air flow over appreciable areas was required. For this purpose, a hot-wire anemometer was constructed which derives its power from a small storage battery. The only electrical measuring instruments required are a voltmeter and an ammeter. The operation, calibration, sources of error, and application of the anemometer offered difficulties which are discussed and analyzed. Line drawings assist in presenting many of the results. It was found that the anemometer could be used to measure free air flow within 3 per cent of the true values if power values of heat dissipation were adjusted for a fixed temperature head. (June 18, 1925.) 10 pp. Price, 5 cents. T288. Comparative Cold-Rolling Tests of Open-Hearth Steel Strip (Deep Drawing Stock) and Electrolytic Iron Strip... . John R. Freeman, jr., and R. D. France A series of tests has been carried out to determine the relative coldrolling properties of electrolytic iron as compared with open-hearth steel especially adapted for deep-drawing operations. Representative lots of the two types of material were cold-rolled under identical conditions in order to determine any difference in behavior in the rolls. The material was rolled under both mild and very severe rolling practice. No evidence developed indicating any marked difference between the two types of material. The following tests were made on samples representing each step in the rolling: Hardness, Erichsen, tensile, and bend tests. In general, the tests indicate that electrolytic iron would be slightly superior to specially selected commercial open-hearth deep drawing stock. (June 24, 1925.) 17 pp. Price, 10 cents. T289. Comparative Slow Bend and Impact Notched Bar Tests on Some Metals.. S. N. Petrenko Comparative impact and slow bend notched bar tests were made on some nonferrous alloys and on some steels in order to determine whether the slowbend test may be used as a substitute for, or as a useful addition to, the impact test. The effect of the shape notch on the impact and on the slowbend values was also studied. The slow-bend test gives lower values than the impact for nonferrous alloys and higher than the impact for steels. The slow-bend method gives results which are, in general, similar to the impacttest results, but it is less responsive to the variations in the notched-bar properties. The slow-bend test gives some values which are related to the tensile strength. It is, however, less convenient for the ordinary routine practice than the impact test. The notched-bar test and, particularly, the notched-bar impact test is very sensitive in showing up the directional differences in the properties of rolled metals caused by their fibrous structure and may be more conveniently used for this purpose than other tests. This refers to the specimens cut in the direction of rolling. (June 27, 1925.) 32 pp. Price, 20 cents. 54168-25-11 CIRCULARS [All Circulars are subject to revision to keep the subject matter current. Inserted in this list of publications is a supplement giving the latest data concerning the latest editions of the Circulars. For example, the supplement gives for each Circular the Circular number, the latest edition number, date, number of pages, and price. The supplement also gives any modification required in the descriptive abstract for revised editions of Circulars. For publications in following list that are out of print, see the supplement to this Circular.] CI. (Now in preparation. Will cover the organization, functions, and work of the Bureau.) C2. Measurements of Length and Area, Including Thermal Expansion. Gives the regulations under which length and area measuring apparatus, such as engineers' tapes, yard and meter standards, end standards, machine-shop gages, precision screws, and calipers are tested by the Bureau, shipping directions, schedule of fees, etc. The fundamental standards of length are described, the inter-relationship of the various units of length is given, and the methods of comparisons of length standards are outlined. C3. Design and Test of Standards of Mass. Contains general information on the fundamental standards of mass; a classification of weights into groups according to use (industrial or scientific); tolerances, and specifications for the construction of weights in each class; a discussion of the several methods of testing and adjusting weights; tables and formulas for correction of weighings for the buoyancy of the air, etc. The regulations governing the testing of weights by the Bureau of Standards and a schedule of fees for such testing are included. C4. Verification of Standards of Capacity. Gives shipping directions and a schedule of fees for metal capacity measures tested by the Bureau of Standards. C5. Testing of Clinical Thermometers. The edition of July 16, 1917, is considerably revised to announce new regulations, effective July 1, 1917, governing the certification of clinical thermometers. Past practice was to issue certificate in the form of a table of corrections at four points, 96°, 100°, 104°, and 108° F; the new certificate will be issued only for thermometers correct within 0.1° F at normal and 0.2° F at 104 and will contain the statement that the thermometer is correct within these tolerances. The Circular contains a full description of the method of testing clinical thermometers and considerable matter of general interest concerning these instruments. C6. Fees for Electric, Magnetic, and Photometric Testing. States the kinds of tests performed and gives the fees established by the Bureau for tests of electric, magnetic, and photometric standards, measuring instruments, and materials. It supersedes the schedules of fees given in older editions of the various circulars upon these subjects, editions of which have been published since 1913 without the lists of fees. The fundamental units used as the basis of measurement are summarized. Specific instructions are given as to arranging for tests and shipping apparatus. C7. Pyrometer Testing and Heat Measurements. Information is given concerning the high-temperature scale, including a list of melting and boiling points suitable for calibration of pyrometers. Descriptions, precautions in use, and the methods of calibration of the various types of pyrometers are given, including thermoelectric, electrical resistance, optical, and radiation instruments. There is also given a list of the tests in heat measurements that the Bureau is equipped to carry out. |