COMPARISON OF THE RESULTS FOR THE ZEEMAN EFFECT AND FOR PRESSURE 



DISPLACEMENT. 



A summary of the theories on the possible connection between magnetic separation and pressure 

 displacement is given on pp. 5-7. The data now at hand permit a considerable extension of the compari- 

 son made in my former paper {40). This is mainly in two directions. First, photographs of titanium arc 

 spectra under pressure made in this laboratory by Mr. H. G. Gale have materially added to pressure 

 measurements for this substance. Although this material has not yet been published by Mr. Gale, he 

 has kindly permitted me to use his values in this comparison. Second, spectra given by the electric 

 furnace under pressure have recently been obtained by me, and the preHminary results (63) bear on one 

 of the questions involved in the present discussion. 



In Tables 11 and 12 the values of the magnetic separations in the second column are taken directly 

 from Tables i and 2 respectively. These values of AX are for the H-components, the mean being taken 

 when there are two or more pairs. Numerous changes have been made as compared to the former paper 

 on this subject, due to better photographs being available. 



The measurements of pressure displacements expressed in Angstrom units are taken from the publi- 

 cations of Humphreys (41'-) and of Duffield (64) for the iron spectrum. For titanium, some measurements 

 are given by Humphreys, but most of the pressure values are from the photographs of Gale. The meas- 

 urements by Humphreys in the third column are for a pressure of 42 atmospheres, his other measurements, 

 for 69 and loi atmospheres, being for only a part of the lines. For the iron spectrum, the displacements 

 of Dufifield for 41 atmospheres are given in the fourth column. For titanium, the measurements of Gale 

 taken for 9 atmospheres total pressure were multiplied by 4.7 to bring them to the same order as those 

 of Humphreys, assuming a direct proportion between displacement and pressure. Occasionally a hne 

 was not obtained by these observers for the given pressures, in which case an approximate value was 

 deduced from the measurement for some other pressure and is accompanied by an interrogation point. 



T;\BLE II. Zeeman Separations and Pressure Displacements for Iron. 



56 



