Chemistry and Physics. 577 



a Pt Pt-Rh thermocouple. The quartz tube was provided with 

 a lateral tube of 3 mm or 4 mm bore in which the solid tellurium was 

 placed, and after this apparatus had been evacuated to a pressure 

 of o - l mra orless, the side tube was sealed off in an oxyhydrogen flame. 

 The pressure of the vapor was varied by sending currents of differ- 

 ent strengths through a nickel wire wound around the side tube. 

 The temperature of the coolest part of this tube was determined, 

 since the pressure inside the main tube depended upon it. After 

 the furnace and lateral tube had been regulated to their respective 

 temperatures, the light from the positive pole of a carbon arc was 

 passed through the vapor and focussed on the slit of a small con- 

 cave grating spectrograph. The absorption spectrum was exam- 

 ined for the interval A 2400 to A 7000, and for temperatures varying 

 between about 500° C. and 1350° C. In one series of experiments 

 the pressure was kept constant and the temperature varied, while 

 in another series a known mass of tellurium was placed in a quartz 

 tube and the absorption spectrum photographed at different 

 temperatures. 



The results of this investigation are summarized by the author 

 in the following words : " 1. The bands in the absorption spec- 

 trum of tellurium extend from A 3900 to about A 6000. In addition 

 to a band spectrum the vapor gives a general selective absorption. 

 The absorption spectrum of tellurium is similar to that of selen- 

 ium, but compared with the spectrum of the latter is displaced 

 toward the red. 2. For small pressures absorption bands are first 

 photographed in the extreme violet (A 3900), and as the pressure 

 increases, absorption bands are also photographed in regions of 

 greater wave-length. At pressures sufficient to show the presence 

 of bands in the region A 5300 — A 6000, there is complete absorp- 

 tion in the violet and blue. 3. When the pressure of the vapor 

 is low, the absorption bands in the region A 3900 — A 4500 dimin- 

 ish in intensity with increase of temperature until they almost 

 disappear at 1200° C. This result may be explained on the 

 hypothesis that the absorption bands are due to complex mole- 

 cules, which are present in tellurium vapor at low temperatures. 

 These molecules are completely dissociated at high temperatures 

 and hence the absorption bands are not visible. 4. The absorp- 

 tion spectra of a constant mass (0 - 002 gm.) of tellurium vapor at 

 1000° C. and 1350° C. do not show any difference. Both spectra 

 show the presence of bands between A 5300 and A 6000 and a con- 

 tinuous absorption from A 5300 to A 3500. The intensities of the 

 bands are not affected by a change Of temperature from 1000° C. 

 to 1350° C From the experimental results it is impossible to 

 determine whether these bands are due to diatomic molecules or 

 more complex ones." — Astrophys. Jour., vol. xxxvi, October, 1912, 

 p. 228. h. s. u. 



Am. Jour. Sci. — Fourth Series, Vol. XXXIV, No. 204.— December, 1912. 



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