INVESTIGATION WITH A ROCK-SALT PRISM. 49 



is double, and occurs at 7.0 /* and 7.3 fi. These two bands are to be 

 noticed with this same region for ethyl alcohol (fig. 38), where there is 

 but one flat band, which would, no doubt, be found complex, using a 

 larger dispersion. 



The 14^ band is also to be noticed, since it occurs in compounds 

 having CH3 and C2H5 groups, while the 12 /u, band is also found in many 

 compounds. 



Ethyl ether has been studied by Angstrom,^ both as a liquid and as a 

 gas. He found that the maximum at 3.45 /x. did not coincide for the 

 two states, the vapor being shifted by 4' toward the long wave-lengths. 

 He claims to have obtained this effect repeatedly, while no shifting was 

 observed by him for other compounds examined in the liquid and the 

 vapor state. In the present work the region of 345 fi for liquid ether 

 was explored at the same time that it was for the vapor. No such shift- 

 ing was observed, as will be noticed in fig. 18, where the curves (indi- 

 cated thus : A A A and x x x ) for liquid and vapor are seen to 

 coincide. The slight difference in the position of the maximum for this 

 day and that for the time of making the complete curve is due to the 

 resetting of the prism in the meantime. 



Ether belongs to the water type of compounds, i. e., the C2H5 takes 

 the place of an H atom in H2O, but it is not apparent in the curves. 



The bands at 7.3 \i and 7.8 yu, almost coincide with those of acetylene. 

 Beyond 7 /x three sets of bands, " triplets," have " constant differences " 

 of their wave numbers, which agree so closely as to lead to the sus- 

 picion that they belong to a spectral series. The two most marked sets 

 are: 



7.0 ,« -^ ^, 10. 14 /i -^ 



7.3 >^i=6o 10.77 ^^^=58 



7.8 >^2=9o „_g >r2=90 



I1.LUMINATING Gas. (Fig. 19.) 

 The sample used was taken directly from the pipes and examined. 

 It contains bands due to CH^, C.H,, C.Hio, CO, CO2, SO,, and HoS. 

 Ordinary analysis shows about 60 per cent of CH4, 6 per cent of CO, 

 2 per cent of CO2, and the remainder principally unsaturated hydro- 

 carbons. The curve is of interest in showing the presence of CO 

 and H2S. 



Oxygen. 

 (Cell, 5.7 cm. ; barom., 74.6 cm. ; temp. 23° ; fig. 20.) 



Made by heating KCIO3 -f MnO,, purified in KOH, and dried by 



passing through a glass tube containing absorbent cotton covered with 



P.O.. 



'Angstrom, loc. cit. 



