48 INFRA-RED ABSORPTION SPECTRA. 



drying in P2O5 the gas was passed into a U-ttibe placed in a freezing 

 mixture of common salt and ice. 



Butane liquefies at 1°, while its isomer liquefies at — 17°. The attempt 

 to liquefy it was not very successful, and the gas collected may have 

 contained the isomer as well as other impurities. 



The transmission minima of ethane (C^Hq) at 2.36/* and 3.39/* and 

 6.85 fi are shifted to 2.4 fx., 3.42 fi, and 6.89 fi, respectively. Beyond 7 fx 

 there are a number of bands which occur as impurities, the most con- 

 spicuous of which are the two at 7.8 ju, and 14 /*, due to ether, and the 

 10.5 ju, band in ethylene. The bands at 8.3 /* and 8.9 ju.(diff. = 0.60 /x) 

 find their counterpart in methyl ether, where they are shifted to 8.58 /a 

 and 9.16 /A (difif.=o.58/A), respectively, and in ethyl ether, where the 

 bands are shifted to 8.75 ju, and 9.25 fi (diff,=o.50/u,), respectively. 



Methyl Ether. (CH3)20. 

 (Cell, 5.7 cm. ; barom., 76 cm.; temp., 22° ; fig. 17.) 

 Prepared^ by heating 1.3 parts of alcohol and 2 parts of sulphuric 

 acid to 140° and washed in KOH to absorb the SOg, and then dried in 



A study of this gas is of interest in connection with ethyl alcohol, 

 with which it is isomeric. A more striking illustration of the effect 

 upon absorption of the arrangement of the atom in the molecule has 

 not been found, except perhaps for the sulphocyanates and mustard oils. 

 From lOjtt to ii/t alcohol (fig. 38) shows transparency, and beyond 

 13 ju, there is complete opacity, while, for methyl ether, the very oppo- 

 site effect was found. Beyond 8 fi the pressure of the ether had to be 

 reduced to 10 cm. of mercury. 



The only apparent impurity band to be noticed is that of butane at 

 5.7 /x. The bands at 2.5 ju, and 3.45 /x and 10.55 /* ^^^ shifted to longer 

 wave-lengths, as compared with those of butane. The 6.9 n band is 

 harmonic with the one at 3.45 fi. This compound, like all the gases, is 

 conspicuous for the great depth of its absorption bands. Curve b is 

 for a pressure of 10 cm. 



Ethyl Ether. (C2H5)20. 

 (Cell, 5.7 cm. ; barom., 74.9 cm.; temp., 24"; fig. 18.) 



For studying this vapor some of the anhydrous liquid was placed in 

 the absorption cell, which evaporated, thus giving a saturated vapor. 

 Frequent opening of the stop-cock kept it at about atmospheric pressure. 



Like the methyl ether, it has very deep bands, which are shifted as 

 compared with the two preceding gases. The 4.75 /x band of methyl 

 ether occurs at 5.15 /a in ethyl ether. The 6.9 /x band of the former 



^Erlenmeyer & Kirchbaumer: Berichte d. Deutsch. Chem. Gesellschaft, 7, 699, 1874. 



