摘要:

The ratio of the Larmour frequency of precession for hydrogen and fluorine, and for sodium and aluminum have been measured with an accuracy of one part in 105:These ratios are corrected for the atomic diamagnetism giving for, γ, thenucleargyromagnetic ratios:A brief description is given of the relevant equipment used in obtaining these measurements.

ISSN:1923-4287    

DOI:10.1139/cjr50a-031

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Using a new low temperature calorimeter, which is briefly described in the paper, the specific heats have been measured from 65° to 300°K. for the following salts: chromium sulphate (hydrated and anhydrous), chromium nitrate, cobalt nitrate, and nickel nitrate (hydrated). Hydrated chromium sulphate was found to have a transition of the second order at 195°K., while the specific heat of the anhydrous salt was quite regular. The hydrated nitrates all showed second order transitions in the neighborhood of 150°K. The entropy changes associated with these transitions have been estimated approximately, and vary from about 0.4 Rfor cobalt nitrate to 1.65 Rfor chromium nitrate, whereRis the gas constant. Pending further evidence, it is tentatively suggested that the transitions are due to the onset of partial rotation of the H2O groups in the crystals.

ISSN:1923-4287    

DOI:10.1139/cjr50a-032

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Equations have been derived for the frequency limits of the attenuation bands, the degree of attenuation, and the phase change of a specific type of filter which cannot be readily analyzed by the side branch method. The characteristics have been verified by measurements on experimental filters.

ISSN:1923-4287    

DOI:10.1139/cjr50a-033

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The quantities of water vapor passing through wood have been measured under the conditions of hydrodynamic flow and of kinetic diffusion. Air and oxygen pass through wood under hydrodynamic flow conditions in accordance with the Knudsen–Poiseuille law. Water vapor passes through wood under hydrodynamic flow conditions in much larger quantities than those predicted by the law. The rate of passage of water vapor under diffusion conditions follows the Fick diffusion law but with a diffusion coefficient that increases with relative humidity. The distinct features of the diffusion and hydrodynamic flow processes are pointed out. Porous, hygroscopic media permit the transfer of water vapor either by diffusion or by hydrodynamic flow, as determined by two distinct sets of conditions, while compact, hygroscopic media permit the transfer of water vapor by diffusion only, regardless of the external conditions.

ISSN:1923-4287    

DOI:10.1139/cjr50a-034

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

This paper describes a spectrophotometric method whereby instantaneous values of a variable flame temperature, in the particular case of nonluminous flames, may be determined and continuously recorded.This new technique, which depends upon the establishment of monochromatic black-body radiation conditions in the flame for a small region in the visible spectrum, involves the continuous measurement of radiation intensity in the above region, the intensity being, thereafter, correlated with the temperature of the flame.The problem of temperature measurement in the general case of nonluminous flames (flames which do not contain an appreciable amount of free carbon in the form of soot) is considered and a brief review of previous techniques employed for this purpose over the past 50 years is given. The basic theory and preliminary experimental justification of the present method are discussed.A description of the apparatus and the experimental arrangement used by the author in a specific application of the present method in the determination of the time variation of temperature in the exhaust flame of a pulse-jet engine is given. This includes details of a special type of spectrophotometer which employs a multiplier photocell as the radiation detecting and measuring element and, also, a "black-body" cavity constructed as a standard radiation source for the calibration of the former instrument. An original technique used to investigate the emissivity of flames colored by alkali metal vapors is described and its application to the present problem shown.Finally, the measurable temperature range of the present apparatus is considered together with the inherent limitations of the new method.

ISSN:1923-4287    

DOI:10.1139/cjr50a-035

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The fast neutrons produced by the triton bombardment of LiF, Li2CO3, LiOH∙H2O, LiOD, and LiOD∙D2O + D2O have been detected, and the thick target yields and their slowing down lengths in graphite measured. The tritons were produced by irradiating the compounds in the high thermal neutron flux of the thermal column of the NRX pile. The spatial distributions of the fast neutrons from the T + D and T + Li reactions were measured in the graphite with indium resonance detectors. The numbers of fast neutrons emitted per second were obtained by comparing the space integrals of the indium activity with that measured when a standard Ra-α-Be source of neutrons was in the position of the lithium compounds. The number of incident tritons was estimated from the measured flux of thermal neutrons at the lithium compound and the total capture cross section of the lithium. The thick target yields were thereby derived. The average cross sections for neutron production by 2.6 Mev. tritons are 1.5 × 10−24cm.2per atom of lithium and 0.41 × 10−24cm.2per atom of deuterium. The slowing down lengths in graphite of density 1.64 gm. per cc. are 19.2 and 23.4 cm. for the neutrons from the lithium and deuterium respectively. The smallness of the latter indicates that inelastic scattering of these 14 Mev. neutrons occurs in graph

ISSN:1923-4287    

DOI:10.1139/cjr50a-036

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The fundamental bases of the differential equation of diffusion are examined. From a dynamical equation defining the motion of the gas, an equation of continuity expressing the law of conservation of mass, and an equation of state giving the relation between concentration and pressure, the differential equations are derived for the interdiffusion of two gases, for the diffusion of vapors, and for the diffusion of gases and vapors through solids. For the diffusion of gases through adsorbing solids, the dynamical equation of the flow is obtained by equating the space derivative of the spreading pressure of the adsorbed film to a resistive force equal to the product of the coefficient of resistance and the velocity of the film. The differential equations derived on this assumption agree qualitatively with measurements for the diffusion of gases through metals when the adsorption can be represented by Langmuir's equation. When the adsorption follows the BET equation, qualitative agreement is found with the diffusion of water vapor through hygroscopic materials. It is also shown that Fick's law is not generally valid as the fundamental equation of diffusion.

ISSN:1923-4287    

DOI:10.1139/cjr50a-037

出版商:NRC Research Press    

年代:1950

数据来源: NRC