314 



INFRA-RED EMISSION SPECTRA. 



pressure, the current being 0.02 ampere. The results are shown in 

 fio-ure 146, which will be discussed in connection with CO, and it will be 

 sufficient to add that the gas was first put into a pipette of phosphorus 

 to remove the oxygen which was present. Starting with a sample of 

 this gas at i mm. pressure, and adding oxygen until the pressure was 

 3.7 mm., no change could be detected in intensity of the 4.75 /* band 

 which would indicate that if the band be due to CO then the CO2 is 

 already dissociated when starting. Occasionally a dark ring or dark 

 patches would appear on the inside of the constricted portion of the 

 vacuum-tube. It would suddenly disappear and then reappear else- 

 where. Whether it was due to carbon in tube, or to the dissociation of 

 CO2, remains undetermined. 



Warburg's work (loc. cit.) shows that the temperature of the axis 

 of the tube is much higher for nitrogen than for hydrogen, so that 

 traces of CO, in nitrogen ought to become the hotter. It was noticed 

 that the 4.75 ix band occurring as an impurity was most intense in nitro- 

 gen, which, if the same amount of COo was present in each gas, would 

 indicate that N was the hotter. 



Carbon Monoxide (CO). 



The CO was made by heating oxalic acid (CoH^Oo) and concen- 

 trated H2SO4 and passed through a KOH solution into a pipette of 

 KOH. The generating flask Vv^as then replaced by a mercury gas 



Fig. 145. 



pipette and a tube of P2O5 on glass wool, and the gas was washed 

 back and forth through the P2O5 for a long time. This sample showed no 

 water vapor lines at low pressures. The emission curves of CO are given 



