50 INFRA-RED ABSORPTION SPECTRA. 



This gas is of considerable interest, because it enters into so many 

 compounds. It shows two large shallow bands at 3.2 ju, and 4.7 ju,, 

 respectively. They are only 4 per cent in depth. It appeared that this 

 might be due to impurities, but repeated attempts to remove them failed 

 to change the intensity. After passing the gas back and forth through 

 a tube of P2O5, from one gas pipette to another, the bands still existed. 

 The oxygen was then placed for three days in an absorption pipette 

 containing concentrated H2SO4, but, as will be noticed in curve b, the 

 bands still remain, showing that their presence is not due to water vapor. 



One sample was not washed in KOH, and then showed the CI band 

 at 4.3 fi. Angstrom^ found this band at 4.28 ju, for pure chlorine. It 

 is interesting to note that Dewar, and also Olzewski, found several 

 absorption bands of liquid oxygen in the visible spectrum. 



Hydrogen and Bromine. 

 (Cell, 6.3 cm.) 

 Generated from c. p. Zn -j- HCl, washed in HoSO^, and dried in P2O5. 

 The hydrogen gas showed no absorption bands. Paschen^ examined 

 hydrogen and nitrogen, but, after repeated measurements, failed to find 

 any absorption bands. 



The vapor of bromine showed no bands. The cell was lined with 

 paraffin to prevent the bromine from attacking the glue. 



Carbon Monoxide (CO). 

 (Cell, 5.7 cm. ; barom., 73.2 cm.; temp., 23° ; fig. 21.) 



Made by heating oxalic acid (C2H4O2) and concentrated H2SO4. 

 This forms CO + COo + H2O. The CO, was absorbed by passing the 

 gas through KOH solution, after which the CO was dried in P2O5. 



As will be noticed in curve a (fig. 21), there was still some COo pres- 

 ent, as shown by the maxima at 2.75 fx and 4.3 ft. After washing the 

 gas back and forth for half an hour, in a burette of KOH, and drying 

 in PjOg the CO2 was entirely removed, as shown by curve b. 



The maxima of CO occur at 2.4 /x and 4.59 /a. Angstrom^ found 

 these maxima at 2.48 fx and 4.52 [i. 



The absorption spectrum of CO was examined to 14 ^u, but no max- 

 ima were found. 



As shown by Angstrom, the fact that the CO band occurs at 4.59 ju, 

 and the CO2 at 4.29 /x invalidates the assumption that molecular weight 

 has a great influence on absorption. 



^Angstrom & Palmer : Ofversigt Kongl. Vet. Akad., No. 6, p. 389, 1893. 

 ^Paschen : Ann. der Physik, 53, p. 334, 1894. 

 ^Angstrom, loc. cit. 



