Empirical formulas for the capacity of level roof gutters have been determined, and data have been obtained on flow in sloping gutters. Metallurgical Information. The staff of the metallurgical division has prepared for the American Society for Steel Treating an elementary treatise on the heat treatment of steel. The exceedingly_large demand for this publication has clearly shown its usefulness. It has been adopted as a textbook in a number of institutions, including the graduate school of the United States Naval Academy.

At the request of the American Iron and Steel Institute a survey of the steel requirements of the aircraft industry has been made. The results were reported to that institute.

Publications.-Principles of the Heat Treatment of Steel, by the Metallurgical Staff, Bureau of Standards, published by American Society for Steel Treating. Steel Requirements of the Aircraft Industry, H. J. French, Amer. Iron and Steel Institute, Yearbook, 1928.

PAPER

Official Testing Methods.-Cooperation in the development of the official paper-testing methods of the Technical Association of the Pulp and Paper Industry has been continued, the chief of the paper section being chairman of the association's paper-testing committee. Methods for testing gloss and opacity were completed and adopted by the association, and a revised edition of the association's Paper Testing Methods was published during the year. The work was assisted by tests and investigations carried out at the bureau. These included: (1) Water-resistance and grease-resistance tests, (2) fiber analysis by the dot method; (3) a study of methods that have been proposed for determining acidity, formaldehyde, and starch; and (4) the development of a method for bulk determination. Samples for analysis by the dot method were sent to various laboratories for the purpose of obtaining data indicative of the concordance that should be expected.

Publication.-Paper Testing Methods, published by Technical Association of the Pulp and Paper Industry.

Measurement of Bulk.-In a study of the methods and apparatus for determining the bulk of paper, it was found that the amount of pressure used is of primary importance. A simple apparatus for controlling this factor was devised. From tests on 11 types of paper it was found possible to specify procedures that will insure substantial agreement between the indications of instruments of various types. A report of the work has been published.

It is recommended that bulk be expressed as (1) bulking thickness, or thickness of a 100-sheet pack; and (2) specific bulk, or the ratio of bulking thickness to ream weight.

Folding Tester.-A_supplementary publication on the Schopper type of folding tester has been prepared. In it an adaptation of the bell-crank lever device to the measurement of the friction of the rollers between which the paper is folded is described and a procedure for periodic inspection and adjustment of the tester is suggested. Sheathing Paper. The research on sheathing papers, made at the request of the National Lumber Manufacturers Association, has been completed. In this work, 36 samples of building papers ranging from ordinary wrapping paper to papers treated with asphalt or paraffin, and made by 14 different manufacturers, were examined.

In addition to the usual strength tests, the papers were tested for water resistance and for air permeability. There was a wide difference in all of these properties. It was concluded (1) that thickness is relatively unimportant, (2) that strength is of signiffcance chiefly in handling the paper during erection, (3) that water resistance and impermeability to air are of prime importance in making a wall weatherproof, and (4) that most commercial papers are capable of performing this function (weatherproofing) sufficiently well.

Fiber Wall Board. A report on the development of a Federal specification for fiber wall board has been prepared for publication. It contains (1) a review of the previous research by Clark and Conley, (2) a detailed account of the experimental work on which the expansion and the flexural strength tests are based, (3) the results of tests of various kinds of commercial boards, and (4) the specification itself.

Roofing Felts.-A study of the effect of using various diluents, including waste paper and sawdust, in the manufacture of roofing felts indicates that relatively large amounts of substitute materials can be used to admixture with waste textile materials without causing difficulty in the manufacturing processes or apparent decrease in the weather-resisting properties of the finished roofing. The results have been prepared for publication.

Rayon. Rag-paper manufacturers are interested in the paper-making quality of rayon, as it occurs frequently in the rags used for making high-grade papers. Six samples of rayon, representing the various products on the market, were treated in the same manner as the rags used for making fine papers, and test sheets were made from the product. The results indicate that this material after passing through the usual paper-making process has no paper-making value and may even be injurious to paper containing it.

Postage Stamps. In cooperation with the Bureau of Engraving and Printing, the processes involved in manufacturing postage stamps is being studied, one complete printing, gumming, and drying unit being used for the purpose. Control of temperature and increased circulation of air in the drying section have a beneficial effect on the strength of the stamps and on their adhesion. A device for controlling the tension of the paper, which is printed wet, has been found to minimize the distortion, and thus to facilitate the perforation. The heavily waxed paper previously used as interleaving sheets in postagestamp books has been found to have an adverse effect on the adhesion of the stamps, and a different type of paper has now been adopted. Stamp-affixing devices have been found to be very efficient when kept in proper working condition. A revolving drum which simulates the service stresses to which stamps are subjected has been devised for testing their adhesion.

The Uses of Glue in the Paper Industry. A handbook of the above title, written by their research associate, G. K. Hamill, and recently published by the Glue Research Corporation (1457 Broadway, New York, N. Y.), contains a summery of the information gathered during an investigation of the uses of glue in the paper industry. The investigation was carried out by the bureau in cooperation with the National Association of Glue Manufacturers.

Publication.-Uses of Glue in the Paper Industry, G. K. Hamill, published by Glue Research Corporation.

88079-30-12

PROTECTIVE COATINGS

Nickel Deposition. From a comparative study of the colorimetric and the electrometric methods for measuring the pH, or acidity, of nickel-plating solutions, the necessary corrections for bringing colorimetric readings into agreement with the standard pH, as defined by the hydrogen electrode, have been determined.

Health Hazards in Chromium Plating.-In cooperation with the United States Public Health Service, a study has been made of the effects of chromic acid spray upon the health of the operators. The maximum permissible content of chromic acid in the air in factories, and the methods and degree of ventilation that suffice to eliminate the hazards have been specified.

Publication.-Health Hazards in Chromium Plating, J. J. Bloomfield and William B.um, Reprint No. 1245 from the Public Health Reports, 1928.

Accelerated Weathering Tests for Nonmetallic Coatings. A study of the weather decay of organic protective coatings by means of accelerated tests that simulate weather effects has been continued. A simple cycle of light and rain is sufficient for testing most of these materials, and numerous data on a variety of coatings are being accumulated by that method, But, a quantitative method for determining the breakdown point of an organic protective coating on metal is needed for the evaluation of the relative durability of such coatings. Such a method has already been described, and a simpler apparatus has since been devised for determining the breakdown point.

Publication.-Unreliability of Visual Inspection of Exposure Tests of Paint, P. H. Walker and E. F. Hickson, Ind. and Engrg. Chem., 20, p. 997, October,

1928.

RADIO

Standards of Frequency. The accuracy of the bureau's frequency standards has been considerably improved. The most recent intercomparisons made between the bureau's standards and those of the Naval Research Laboratory and of the Bell Telephone Laboratories show that the three laboratories agree within 1 part in 100,000.

Several piezo oscillators developed by various laboratories have been studied. A number of their valuable features were incorporated in two piezo oscillators designed and constructed by the bureau, in which special attention was paid to temperature control and to the mounting of the quartz plate. In recent tests, the relative variations of these two oscillators were found to be less than 5 parts per million. A primary frequency standard of special design has been ordered from the Bell Telephone Laboratories (Inc.), and is under construction in their shops. Auxiliary apparatus which will be necessary for automatic operation of this standard has been developed and its construction begun. This standard is guaranteed to have no error greater than 1 part per million, and is expected to be less than that.

Special piezo oscillators sent to the bureau by the General Electric Co., the Westinghouse Electric & Manufacturing Co., and the Naval Research Laboratory have been compared at regular intervals. The inconstancy of these oscillators, as submitted, was about 5 parts per 100,000. By changing the temperature control on two of them the variations were decreased to 1 part in 100,000.

A theoretical and experimental study of the operation of the quartz plate in a piezo oscillator has been made for the purpose of securing fundamental data that will permit the best possible use of piezoelectric phenomena in the preparation of very accurate frequency standards.

The accuracy with which piezo oscillators used by broadcasting stations can be tested has been increased about tenfold by the use of a method, developed at the bureau, that gives a calibration directly in terms of a standard, temperature-controlled piezo oscillator, a frequency meter being used only for identifying the order of the harmonics.

Publication. A System for Frequency Measurements Based on a Single Frequency, E. L. Hall, Proceed. Inst. of Radio Engineers, 17, p. 272, February, 1929. Transmission of Standard Frequencies.-Standard frequency signals, covering the range 125 to 7,300 kilocycles, have been sent once each month on advertised schedules. The frequency was based on a temperature controlled, piezo oscillator, and the inaccuracy of setting seldom exceeded 5 parts per 100,000. The transmitters used for sending these signals have been reconstructed so as to permit still closer frequency setting and control, and to give greater output.

Radio Field Intensity.-An accurately constructed condenser antenna has been installed on the south bank of the Potomac River, and used as a source of radiation of which the field intensity can be measured by means of field intensity sets installed at Hains Point, approximately 3,200 meters distant. This transmission being entirely over water, it is possible to calculate the field intensity that corresponds to the dimensions of the antenna and the strength of the current. This gives a check on the value indicated by the field intensity set. The simple field intensity sets developed by the bureau were shown to have an apparent error which increases with the frequency. In an attempt to reduce this error, a study was made of simple methods of attenuation, including a radio-frequency transformer. While some improvement was obtained, there is still an apparent error of more than 15 per cent at the higher frequencies. A field intensity set, designed by the Bell Telephone Laboratories, was purchased, and measurements made to check its calibration. This set was found to show a discrepancy similar to that found in the bureau's set.

RAILROAD-TRACK SCALES

Commercial-Track Scales.-The track scale testing equipments of the bureau have been operated in 23 States, and a total of 726 commercial-track scales of which 434 were owned by railroads, 288 by industries, 4 by Federal Government agencies, and 1 by a municipality, have been tested. It was found practical to adjust 54 of these scales so as to improve their accurracy, and to correct faulty mechanical conditions in 12 others. The results of the tests are detailed in the table below. Of the scales tested, 71.8 per cent were within the tolerances usually allowed; the average error for all the scales tested was 0.20 per cent of the applied load. In each case, there is a slight improvement over the conditions of previous years.

Grain-Weighing Track Scales.-Included in the preceding table are 97 scales that are used for weighing grain, and are therefore subject to a special tolerance, fixed for scales in this service by Interstate Commerce Commission docket No. 9009. Of these scales only 43, or 44.3 per cent, were correct within this special tolerance. The average error for all these scales was 0.15 per cent. The experience of the bureau indicates that the design and construction of the majority of these scales are such that they are not adapted for maintaining the tolerance required, even though frequently repaired and adjusted.

Master Track Scale Depot. This station, located at Clearing, Ill., and put into operation in May, 1928, has functioned throughout the year, and 44 track scale test cars have been weighed and adjusted to standard weight value. As a corollary to this work, 27 track scale test cars were weighed in the field by substituting them against the standard weights of the track scale testing equipments, utilizing commercial track scales. While this test is necessarily inferior to weighing the car on a master scale, the service is at times of great value; it is furnished when for any reason the transportation of the test car to a master scale is not practical or when the wheel base of the car is longer than the rail length of the master scales in use. During the year the personnel and records of the track scale section were moved to the depot, and the work of the section will hereafter be concentrated there.