ABSORPTION SPECTRA AND CHKMICAL CONSTITUTION. 



165 



pared by the reduction of isonitrosoacetone in accordance with the 

 directions given by Gabriel and Pinkus.^ It boiled constantly at 154- 

 155° ("corr.) under atmospheric pressure. 



Scale of Oscillation Frequencies. 





0.2 



7^ }-i 



HI o 



3 "■ 



2 : 5-Dimethylprazine. 



A layer 25 mm. thick of a solution of dimethylpyraziue containing 

 1 mill.-mol. in 100 c.c. of absolute alcohol cuts off all rays beyond 

 ^ j\ 2994. On reducing the thickness of the layer to 10 mm. an absorp- 

 tion band makes its appearance, reaching from '/X 3064 to ^ jX 4321. 

 This band is very persistent, and is still traceable in a layer 1 mm. thick 

 of a solution containing 1 mill.-mol. of the substance dissolved in 500 c.c. 

 alcohol. The band of dimethylpyrazine is thus both wider and also more 

 persistent than that of pyridine. These results are shown on the curve 

 above. 



Ilexamethylene. — In the paper already referred to, an account was 

 also given of the absorption spectra of diketohexamethylene. Previous 

 investigations had shown that piperidine- and hexachlorobenzene ' 



' Her. 1893, 26, 220{;. - Hartley, Trans. Cliem. Soc., 1885, 47, G91, 



•' Hartlc}', Trans. Chcm. Soc, 1881, 39, 15;'. 



