INVESTIGATION WITH A ROCK-SALT PRISM. 75 



pounds. The general absorption is somewhat different than the oils, 

 which indicates more bands not resolved with the small spectrometer. 



DODECANE. CuH28. (Fig. 64.) 



In addition to the small spectrometer examination, the large one was 

 used, with the result that four small bands were found between 4 and 

 6 fi. The other bands are much deeper because a film o.oi mm. was 

 used instead of a cell of 0.15 mm. thickness, as for the small spectro- 

 meter. This shows that the bands are sharp and narrow, and for this 

 reason are blotted out when using the thicker cell and the smaller dis- 

 persion. 



The bands at 3.43 fi and 6.86 /i are harmonic. 



OcTADEcvxENE. CisHse; Tetracosylene, CmHis. (Figs, yz and 74.) 

 These two compounds were also re-examined with the large spec- 

 trometer, but no new bands could be found between 4 and 5.5 {i. The 

 bands at 3.44 and 6.87 fi are harmonic, and have no indications of being 

 complex. A small band exists at 6.6 /n, where the curve is very asym- 

 metrical for the small spectrometer. 



It has just been noticed that dodecane (CiaHge) has several bands in 

 the region where these two compounds are transparent. It would have 

 been interesting to determine whether this is due to the difference in 

 structure of the two series of compounds. It seems quite probable that 

 this is due to structure, but time did not permit an examination of more 

 compounds, using the large spectrometer, in order to thoroughly estab- 

 lish this fact. 



MoNocHLORTRiDECANE, CisHkCI ; Monochlorheptadecane, CmH»CL (Fig. 7$.) 



The two chlorine compounds studied do not happen to be substitu- 

 tions in the distillates examined. However, since they have the same 

 maxima as all the disillates, it shows that the introduction of a chlorine 

 atom has little effect on those maxima. 



HYDROCARBO>f. CioHmS. (Fig. jS.) 



This product was obtained from the sludge of Ohio petroleum. Its 

 properties are unknown. The transmission curve is essentially the 

 same as that of the oils. It seems more transparent than the oils 

 beyond 1 1 /n. 



ASPHALTUM. (Fig. 44.) 



Asphaltum is a mixture of different hydrocarbons, part of which are 

 oxygenated. It is of variable composition. Two specimens were 

 examined. The film of varnish was first examined, after it had been 

 drying for several months. Thinking that some of the solvent might 



