Document containing principle and supplementary papers presented at the Fourth International Symposium on the Chemistry of Cement, as well as discussions of those papers by members of the Symposium. Index begins on page 551.

From Synopsis: "This paper deals mainly with cement paste in terms of its porosity, internal surface area, interaction between solid substance and evaporable water and related properties."

From Introduction: "This Monograph has as its purpose the compilation and analysis of the extensive radio refractive index data available within the Central Radio Propagation Laboratory of the National Bureau of Standards. This will be accomplished by presenting both tabulations of basic data for specific locations and charts for interpolation to any location."

"The definition of color, as a characteristics of light, and the basic principles of its measurement are given. The reduction of spectrophotometric data to three chromaticity coordinates by means of the three-function CIE standard observer system for colorimetry is described. Various methods of direct colorimetry, and visual and photoelectric methods of colorimetry by differences from material standards are treated" (p. 1).

Report discussing the selection, specifications, and use of signal-light colors. It discusses the nature of the problem, and the mathematical representation, recognition, production, control, and use of such colors. The characteristics of different types of chromaticity boundaries and the purpose and effect of the requirement for similarity of chromaticity characteristics are given special consideration. The treatment is varied according to the intended use. The discussion of the control of colors and the section on the use of colors are nontechnical, whereas the section on the production of signal colors is designed for the colorimetrist who is faced with the problem of selecting limit filters or drafting a specification.

Report compiling the melting points of 70 metal oxides published prior to January 1963. Both the original melting point and the equivalent value based on the International Practical Temperature Scale of 1948 are presented. Included in the survey is information on pertinent experimental details such as the method of temperature measurement, purity, furnace type, and environmental conditions.

Report discussing the VLF, ELF propagation in the earth-ionosphere waveguide emphasizing the total field found by summing all modes which contribute appreciably. Solutions are given and calculations are made for a homogeneous isotropic ionosphere, a homogeneous ionosphere with a constant radial magnetic field imposed, and an ionosphere with a magnetic field of arbitrary dip angle.

Report issued by the Bureau of Standards over studies on the importance of conductive flooring in hospitals. Types of conductive flooring are compared, and tested. The methods and results are presented, and discussed. This report includes tables, illustrations, and photographs.

Report presenting a table of corrected optical pyrometer readings which enables optical pyrometer users to convert observed temperature immediately to the true temperature, if the effective emissivity of the material being observed is known. The table gives observed temperatures from 1,000 to 3,000ºK in increments of 5 degrees, from 3,000 to 5,000ºK in increments of 10 degrees, from 5,000 to 10,000ºK in increments of 50 degrees, and from 10,000 to 39,900ºK in increments of 100 degrees. For these, true temperatures are tabulated for 49 emissivities ranging from 0.02 to 0.98 in increments of 0.02.

From Introduction: "In this paper are presented the results obtained to date from the inspections of steel pilings. The investigation will be continued by additional inspections of pilings in other parts if the country in order to cover a wider range of soil environments."

From Scope of Investigation: "The work reported here is part of a continuing program concerning the long-term volume changes in concretes made from lightweight and normal-weight aggregates. The creep, drying-shrinkage, and strength data presented are for concretes made with 24 expanded shale lightweight aggregates and 5 natural, normal-weight aggregates. These aggregates were from widely separated geographical locations and were to be representative samples of aggregates being used in the production of structural concretes."

Report presenting graphs of the change in input impedance of electrically short dipole antennas in the presence of an isotropic and homogeneous ground which considers four types of antennas: horizontal and vertical, electric and magnetic dipoles. Curves of the change in both the input resistance and reactance are shown for a wide range of values of the frequency, antenna height above the ground, and electromagnetic ground constants.

From Abstract: "This report describes the use of an air-filled aluminum-alloy ionization chamber to determine the energy transported by a bremsstrahlung beam with maximum photon energy in the range 6 to 170 Mev. This report can be used to construct a replica chamber to determine its absolute calibration between 6 and 170 Mev under a variety of experimental conditions."

From Introduction: "An improved high-temperature gage was needed, and in an attempt to fill this need an investigation was initiated in February 1954 in the Enameled Metals Laboratory at the National Bureau of Standards. The present Monograph constitutes a final summary on this program."

From Introduction: "The present report describes the condition of all of the porcelain enamels after exposure for 3 yr."

Report issued by the National Bureau of Standards over studies conducted on the effects of mortar on the strength of masonry. Materials, methods, and results are presented and discussed. This report includes tables, illustrations, and photographs.

Report discussing the transient magnetic behavior of a paramagnetic substance, after an initial disturbance, considered theoretically for a variety of situations in which the lattice temperature rises as a result of energy flow from the magnetic (electron spin) system. Next, the opposite extreme is considered - that in which the resonant and remaining modes are totally uncoupled. Finally, there is a consideration of the case of spins coupled only to the resonant phonons, which in turn are coupled to a constant temperature bath, whether this be the helium or the remaining modes.

From Introduction: "The object of this research was to identify and study some of the factors involved in premature failures and to relate the pertinent factors to roof performance."

From Introduction: "Following the guidelines established by this committee, several commercially developed precision connectors have appeared on the market which have led to the wide use of the precision coaxial lines as immittance standards. This paper has been prepared to alleviate this situation by providing graphs from which the electrical parameters of the lines may be determined rapidly and accurately."

From Abstract: "This document is the final report of research carried on in the Electron Physics Section of the National Bureau of Standards during the period from February 1, 1955 to March 1962 in developing an electron optical method for the visualization of low-pressure gas flow."

From Introduction: "The purpose of the paper is to discuss the assumptions and the reasoning by which the calculations described in the Engineering Manual were derived from the data in [1]. The relevant curves from [1] are given in Appendix A and the technical charts from the Engineering Manual are given in appendix B."

From Introduction: "The purpose of this report is to present an analysis of time variations in: (1) the phase (relative to a stable phase reference) if a 9414 Mc/s signal transmitted over this path, referred to hereafter as single-path phase data; (2) the phase observed at one receiving antenna relative to that observed at an adjacent antenna, referred to as phase difference data; (3) atmospheric refractivity as recorded by a microwave refractometer located at the Haleakala terminal; (4) the wind velocity at both ends of the path, and (5) surface atmospheric refractivity measured at 5 stations located on or near the path."

From introduction: "The goal of the work was to provide lists of the principal lines of the elements generally observed under ordinary conditions in arc spectra, together with their relative intensities on a true scale of relative energy."

From Abstract: "The results of an investigation of lightweight, precast cellular concrete planks are given. Fire tests were made of two floor and five roof specimens made up of these planks. Variables, included density of the cellular concrete, thickness and span of the planks, reinforcement, and cover for the latter."