ISSN:0034-6748    

DOI:10.1063/1.1751947

出版商:AIP    

年代:1935

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751948

出版商:AIP    

年代:1935

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751949

出版商:AIP    

年代:1935

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751950

出版商:AIP    

年代:1935

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751951

出版商:AIP    

年代:1935

数据来源: AIP

摘要:

The radium content of ordinary materials is determined by removing and measuring the radon which is in equilibrium with the radium. I. Generalization of the direct fusion furnace method now permits the rapid and complete deemanation ofanysolid by direct boiling at 2000°C. II. Improved boiling apparatus for the removal of radon from liquids avoids loss of traces of radon by absorption. III. Gaseous samples, at atmospheric pressure, may be examined directly for radon. IV. Double ionization chambers, coupled to a high sensitivity string electrometer, permit observations on very feeble sources. Statistical fluctuations in the emission of contamination alpha‐rays from the ionization chamber walls impose a natural observational limit of 7.2×10−14(n)−½curies of radon, when the ionization currents are observed fornhours. V. Photographic recording of the ionization current, with hourly automatic recalibration of the electrometer at three arbitrary potentials, makes possible long runs and higher precision, particularly for weak sources. VI. Induction, null‐induction and ionization methods for the measurement of the electrostatic capacity of ionization chamber systems are described. VII. Caution is given against a spurious ionization, of unknown origin, occasionally observed in connection with radon tests. VIII. The flow method for the measurement of thoron is shown to be more applicable to liquid samples than to solids. Under normal operating conditions the emanating power of liquid samples is about 0.6. IX. Mean values of the radium content of certain classes of rocks, sea waters and organisms are given.

ISSN:0034-6748    

DOI:10.1063/1.1751952

出版商:AIP    

年代:1935

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751942

出版商:AIP    

年代:1935

数据来源: AIP

摘要:

A number of balanced, single‐tube, direct‐current amplifier circuits are compared, which are applicable to the four‐element, low grid‐current vacuum tube. The balance equations are stated for the most generally useful circuit, and magnitudes of the tube characteristics involved are given for the Western Electric No. D‐96475 Tube. Experimentally determined values of circuit constants observed under balance conditions are also given. The stability of the circuit is discussed, and a convenient procedure for obtaining a balance by experimental methods is suggested.

ISSN:0034-6748    

DOI:10.1063/1.1751943

出版商:AIP    

年代:1935

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751944

出版商:AIP    

年代:1935

数据来源: AIP

摘要:

A photoelectric densitometer is described which makes use of the remote cut‐off characteristic of a 58 type thermionic tube to give a meter reading which is very nearly proportional to density. Commercial alternating current is utilized throughout, resulting in a convenient and portable type of instrument. A method is described by which it can also be used to measure the blackness of opaque objects.

ISSN:0034-6748    

DOI:10.1063/1.1751945

出版商:AIP    

年代:1935

数据来源: AIP