摘要:

Discussion of conditions necessary for accuracy in weighing, and tests available to chemists. Sharpness and straightness are tested optically and mechanically. Formulae are given for arm ratio, alignment, and parallax (the departure of the edges from parallelism with each other), from which gravimetric methods are derived. Tolerances are suggested for use in specifications to control repairs and compare bids.

ISSN:0034-6748    

DOI:10.1063/1.1770369

出版商:AIP    

年代:1945

数据来源: AIP

摘要:

Mercury is allowed to flow through a narrow non‐conducting pipe provided with two pick‐up electrodes at the ends of a diameter. In the presence of a magnetic field an e.m.f. is induced in the moving mercury. The potential difference detected between the electrodes is due to the component of the local magnetic field perpendicular to the pipe axis and to the diameter along which the electrodes are located. The device permits the establishment of the direction of the local field without introduction of a ferromagnetic body which might distort it. The magnetic field intensity in a sharply localized region can be determined. The instrument gives a direct reading proportional to the magnetic field intensity and lends itself to the study of rapidly varying transient fields as well as of constant ones. Fields of less than one oersted can still be easily detected. The magnetic field can be measured absolutely. Two ways of propelling the mercury are described. One of them utilizes gravity, and in the other method electromagnetic forces exerted upon a liquid conductor in a magnetic field are used.

ISSN:0034-6748    

DOI:10.1063/1.1770370

出版商:AIP    

年代:1945

数据来源: AIP

摘要:

A new and simple instrument which can be employed automatically for the rapid and precise determination of x‐ray back‐reflection lattice spacings is described. The instrument is essentially a precision back‐reflection focusing camera containing a Geiger‐Mu¨ller counter, a pin‐hole collimator system, and a movable x‐ray disk baffle with a specially designed circular slit system. Once the instrument is calibrated, the lattice spacings are measured by the position of the slit system on disk which in itself is part of a simple micrometer measuring device. The instrument is capable of high precision and great rapidity in the measurement of lattice constants and their changes.

ISSN:0034-6748    

DOI:10.1063/1.1770371

出版商:AIP    

年代:1945

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1770372

出版商:AIP    

年代:1945

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1770373

出版商:AIP    

年代:1945

数据来源: AIP

摘要:

A CAPILLARY arc ion source for a 60‐inch cyclotron is described utilizing a direct‐current filament supply. This has permitted 80‐hour filament life with large deuteron beams. Stability of the arc and its operating conditions and construction are indicated.

ISSN:0034-6748    

DOI:10.1063/1.1770374

出版商:AIP    

年代:1945

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1770375

出版商:AIP    

年代:1945

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1770377

出版商:AIP    

年代:1945

数据来源: AIP