ISO BELL SYSTEM TECIIXICAL JOURNAL 



" The Vapor Pressures of Rochelle Sail, the Hydrates of Soiiiiim and 

 Potassium Tartrates and Their Saturated Solutions."' H. H. Lowry 

 and S. O. Moriian. The vapor pressures were determined by a static 

 meth(Kl at several temperatures between 15° and 40°. Tempera- 

 tures were controlled to ±0.1° and the pressures read to ±0.1 mm. 

 The measurements on the saturated solution of Rochelle salt show 

 that the solid phase in such a solution is unstable above 40°, in agree- 

 ment with other investigators. 



Minimal Length Arc Characteristics.^ H. E. Ives. This paper is a 

 stu(i\' of the electrical discharges which occur between opening con- 

 tacts. It is found that the discharge occurring when currents below 

 a certain \alue are broken are atmospheric sparks corresponding to a 

 definite breakdown voltage, which in the case of air is about 300 volts. 

 Above a critical value of current, which is different for every material, 

 the discharge is an arc, in which the voltage corresponding to the 

 discharge varies with current. Spectograms taken in the two regions 

 show only the air spark spectrum for all materials below the critical 

 current and the arc spectra of the materials above the critical current. 

 The characteristic equations of the arcs caused by the opening con- 

 tacts are deri\-ecl and are used to obtain expressions for the cinrent 

 \s. time relations at the opening contact. 



The Dependence of the Loudness of a Complex Sound Upon the Energy 

 in the Various Frequency Regions of the Sound.'' H. Fletcher and 

 I . (". STEiNBERfi. Two complex sounds were studied, one with a con- 

 tinuous energy frec|uency spectrum corresponding to connected speech, 

 the other a test tone ha\ing discrete frequency components. B>' 

 means of filters the energy was removed from all frequencies either 

 above or below a certain frequency, and the resulting decrease in 

 loudness was measured b>- attenuating the original soimd without 

 distortion imtil equal in loudness to the filtered sound. Taking the 

 average results for six observers, this decrease was found to depend 

 on the absolute values of the loudness. For a loudness of 22 units 

 alxne threshold, each frequency region contributes to loudness in 

 proportion to the energy in that region weighted according to the 

 threshold energy for that frequency. For a loudness above 30 units, 

 however, this is no longer true, because of the non-linear character of 

 the response of the ear. B\' assuming each frequency region con- 

 tributes in proportion to a fractional power of the weighted energy 

 of that region, values of the total loudness in agreenu'til with ob- 



'Joiir. Am. Cliciii. Soc, \ol. 4.S, pp.' 2192-2196, 1924. 



•Journal of the Franklin Institute, \'ol. 198, pp. +37-474, 1924. 



' Physical Kcvicw, \dI. 24, page 306, 1924. 



