ISSN:0034-6748    

DOI:10.1063/1.1749097

出版商:AIP    

年代:1933

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1749098

出版商:AIP    

年代:1933

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1749099

出版商:AIP    

年代:1933

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1749100

出版商:AIP    

年代:1933

数据来源: AIP

摘要:

The dispersion data for rocksalt originally determined by Paschen are corrected to 25°C with the use of temperature coefficients derived from the measurements of Liebreich. Values of the angle of minimum deviation of a 60° prism and the prism table angles from the sodiumDlines for a spectrometer with the Wadsworth mounting of a 60° prism and plane mirror are calculated for 25°C. Tables are given with which corrections may be easily made for temperatures other than 25°C and for prism angles between 59 and 61°.

ISSN:0034-6748    

DOI:10.1063/1.1749101

出版商:AIP    

年代:1933

数据来源: AIP

摘要:

The apparatus described was developed to make possible a determination of thermal critical temperatures and the temperatures at which allotropic modifications take place, etc.; such determination to be accurate enough to be the basis for investigating the constitution and for determining or modifying heat treating practices for alloys now being investigated at the Michigan College of Mining and Technology. The assembly has been found satisfactory because of its flexibility and degree of accuracy and because of the ease with which it is operated, the arduous task of constant observation by a laboratory technician not being required as in the case of most similar apparatus. In addition, the apparatus is flexible and can be used for investigating other properties such as resistivity and thermoenergy. The records are made automatically and are sharp and easily read and interpreted. The important parts of the apparatus are standard, easily obtained and readily assembled; this constitutes an additional and important advantage.

ISSN:0034-6748    

DOI:10.1063/1.1749102

出版商:AIP    

年代:1933

数据来源: AIP

摘要:

This article reviews the various methods previously used to initiate the discharge in commercial types of gaseous conduction arcs and details a recently developed method with the use of a copper oxide rectifier to supply direct current for the starting of alternating‐current arcs.

ISSN:0034-6748    

DOI:10.1063/1.1749103

出版商:AIP    

年代:1933

数据来源: AIP

摘要:

For the removal of radon from liquids, simplified apparatus, including a special reflux condenser, free from carry‐over difficulties, is described. For the measurement of small quantities of radon or thoron, cylindrical ionization chambers, with moisture proof insulation, together with a removable head, evacuated, bifilar electrometer are described. The importance of constancy of the background ionization due to cosmic and local radiation is emphasized, and precautions are described which insure a highly constant background in the present type of apparatus.

ISSN:0034-6748    

DOI:10.1063/1.1749104

出版商:AIP    

年代:1933

数据来源: AIP

摘要:

New principles for removing radon from rocks and for measuring minute quantities of radon are presented. Powdered rock specimens are boiled without flux by direct heating in an evacuated, graphite‐resistance furnace. The duration of heating is 2½ minutes, which is to be compared with about one hour for the quickest of former methods. The gases from the melt are led to the ionization chamber through an electrostatic ion‐trap. A small insulation drying device in the ionization chamber protects the amber from water vapor. The natural observational limit for measurements of small quantities of radon is defined as the point at which the average ionization from the radon just equals the probable statistical variation in the background ionization due to cosmic and local radiation, and an apparatus is described which permits measuring radon down to this limit. A string electrometer measures only the difference in ionization in two identical ionization chambers, both of which contain the same background gases, but only one of which contains the radon to be measured. A systematic study of the percentage of the total radon removed from biotite granite as a function of (a) temperature, (b) duration of heating, (c) fineness of sample grains, showed that temperature is the only important factor, and that 1800°C effects complete radon removal.

ISSN:0034-6748    

DOI:10.1063/1.1749105

出版商:AIP    

年代:1933

数据来源: AIP

摘要:

A simple method of measuring the refractive indices of transparent liquids is described, in which a watch‐glass serves to give the liquid the form of a plano‐convex lens. The image of the maker's trademark on an incandescent lamp is focussed by means of the liquid lens on a movable screen. The screen is supported on an optical bench mounted vertically. By using the image equation, 1/a+1/b=(n−1)(1/R), the refractive index,n,may be determined. A Wallace type G color filter is employed to give results comparable with the values ofndetermined with Na light. Results are given for distilled water, toluene, benzene and carbon tetrachloride. The greatest source of error lies in the vibration of liquids of low viscosity, which introduces difficulties in focussing.

ISSN:0034-6748    

DOI:10.1063/1.1749106

出版商:AIP    

年代:1933

数据来源: AIP