I2O EMISSION SPECTRUM OF BURNING CARBON DISULPHIDE. 



present examination the lower part of the flame was examined. The 

 lamp consisted of a tin lubricating-oil can, the neck of which was 5 cm. 

 long, to prevent heating the CS 2 and thus avoid an explosion. Julius 

 (loc. cit.) examined the upper and the central parts of a CS 2 flame and 

 found that for the central region the maximum at 6.75 /x is more intense 

 than the one at 7.45 /A, while for the upper region the 7.45 p. band is the 

 more intense. This is to be expected, for the 6.75 p band is evidently 

 due to hot CS 2 . In the lower part of the flame the combustion is incom- 

 plete and hence the hot vapor ought to be more intense than nearer the 

 top. In the present examination the lower part of the flame was used, 

 and the ratio of the intensities of these two bands is still greater than 

 that found by Julius; here the ratio is 34 to 73, while Julius found a 

 ratio of 16 to 22 for the central part of the flame and a ratio of n to 8 

 for the top. 



The band at 7.4 /A is in common with the absorption band of SO 2 and 

 since Julius found this band also in burning sulphur, it no doubt belongs 

 to this gas. Then the interesting question arises, "Why is there no 

 emission band at 8. 7 /A?" The question must be left unanswered. It 

 is interesting to notice, however, that the 8.7 /* band is found in H,SO 4 , 

 and in sulphates, and appears to belong to the SO 4 ion, while another 

 band found in SO 2 gas at 10.37^ occurs in fuming H 2 SO 4 and has been 

 attributed to SO 3 by Pfund (loc. cit.). 



The bands at 2.7 and 4.35 //, are in common with the emission bands 

 of CO 2 and are no doubt due to the combustion of the lamp-wick. 

 This is one of the few examples of the emission of a heated gas during 

 the process of combustion. Water vapor and CO,, are other examples 

 studied by Rubens and Aschikinass, but in the emission of a flame 

 these are products of combustion. Kayser in his Spectroscopy very 

 aptly remarks that the emission band of methane (CH 4 ) at 3.3 ju has 

 never been observed in a flame. This is a very weak absorption band, 2 

 however, and might not appear, just as was found for the 4.6 p. band 

 of CS 2 . The 6.75 fj, band, which coincides with that of CS 2 , was 

 ascribed to COS by Julius, who records its maximum in wave-lengths 

 at 8.48^1. The 7.45 /A band of SO 2 was thought to be at 10.01 //,. The 

 emission spectra of H 2 O and CO 2 have been redetermined by others 

 and need not be mentioned here. It will be sufficient to add that for 

 CO, the maximum of emission depends upon the temperature. Whether 

 the SO, band at 7.45 ^ shifts with change in temperature has not yet 

 been determined. The only other emission band that needs correction 

 is that of HC1 at 3.68 /*. A more probable value is 4.05 p, which is close 

 to the HC1 band, found by Angstrom and Palmer 1 at 3.41 /x (cor- 

 rected = 3. 98). 



'Angstrom and Palmer : Ofversight Kongl. Vet. Akad., No. 6, p. 389, 1893. 



