68 INFRA-RED ABSORPTION SPECTRA. 



the enormous band at 4.78 fx is an insignificant line at 4.68 jw in the sul- 

 phocyanate, while just the reverse is true of the 10.2 fx. band. 



Ethyl Sulphocyanate. CaHs— S— C=N. (Fig. 52.) 



The substitution of an ethyl for a methyl group has left the regions 

 at 3.4 fi and 4.68 fi of methylsulphocyanate undisturbed. Elsewhere the 

 spectrum is entirely rearranged, just as was noticed in changing from 

 CH3I to C0H5I. The band at 7.93 fx is new, and is not found in the 

 following isomeric compound. 



Ethyl Mustard Oil (Ethyl Isosulphocyanate). GHb — N=C=S. (Fig. 52.) 



The effect of structure is just as marked as in methyl mustard oil. 

 In changing to the ethyl the 3.4 //, and 4.78 ^ bands have not shifted. 

 New bands occur at 7.53 fx and 8.98 fi. The 4.78 fx band is as strong as 

 ever. No new bands were found at 3 /^ when examined with the large 

 spectrometer. 



Allyl Mustard Oil. CsHs— N=rC=S. (Fig. 53.) 



The large spectrometer was used to examine this compound, and 

 consequently the exploration could not be extended beyond S fx. The 

 results were as anticipated. A large band occurs at 4.8 /*, just as in the 

 other mustard oils. The region at 7 /* and 7,53 fx is the same as in ethyl 

 mustard oil. The 1.70 yu, and 3.4 /a bands are harmonic and are to be 

 found in all compounds containing CHg-groups. The curve at 6.8 fi is 

 very asymmetrical, and no doubt that band is obliterated by the one at 

 7 fx. The 4.8 jx band is double, with maxima at 4.5 p. and 4.85 /*. For 

 the other mustard oils examined with the large spectrometer, this band 

 was too opaque to determine the number of separate lines in it. The 

 absence of a band at 3 /a is to be noticed, since it occurs in several com- 

 pounds in which the N atom is differently bonded. 



Phenyl Mustard Oil. CbHo— 'N— C— S. (Fig. 54.) 



This benzene derivative has the chemical characteristics of the mus- 

 tard oils. It remains to be seen what relations it has in transmitting 

 infra-red radiation. 



The first thing to be noticed is its greater opacity than benzene, so 

 that for the first cell used (0.18 mm.) it became practically opaque at 

 4.9 /A. This is one of the few substances investigated which does not 

 have a deep band in the region of from 3.3 fx to 3.6 fx and then become 

 more transparent at 4 fx. Instead of this the curve continues to drop 

 from 2.5 IX to ^ fi, with only one break at 4.8 fx, which band is to be 

 found in the mustard oils. 



