214 Prof, W. R. Dunstan. On the Occurrence of [June 6, 



methyl indole. It remained to determine whether it corresponded 

 with any of the known isomeric methyl indoles. These are Pr-1 

 methyl indole, which is liquid above —20° C. ; Pr-2 methyl indole 

 (methyl ketole), which melts at 59° 0. ; Pr-3 methyl indole (skatole), 

 which melts at 93—94° C. (Nencki), 95° C. (E. Fischer), and Bz-3 

 methyl indole, which melts at 58° C* 



A crystalline specimen of the methyl indole was prepared from the 

 picrate by distilling it with dilute ammonia. The distillate was 

 extracted with ether, and the residue left by the evaporation of the 

 ethereal solution was crystallised from water. These crystals were 

 observed to melt at 93'5° C, and were, therefore, identical with Pr-3 

 methyl indole, the skatole of Brieger. To completely confirm this 

 conclusion a synthesis of skatole was made from propylidene-phenyl- 

 hydrazide, and the properties of the synthetical skatole were found 

 to be identical with those of the skatole from Geltis reticulosa. It 

 was not possible with so small a quantity of material to estimate 

 the amount of skatole contained in the wood, but it is extremely 

 small, and is certainly considerably less than 1 per cent. 



Conflicting statements exist with reference to the odour of skatole. 

 The skatole from Geltis reticulosa undoubtedly possesses a strong faecal 

 smell. Yon Baeyer has stated that when pure, skatole has no faecal 

 odour, while Brieger, Emil Fischer, and others assert that it has. 

 Some curious facts were observed during the course of this investiga- 

 tion which may throw some light on the cause of this divergence of 

 opinion. It was noticed that the faecal smell is most marked when 

 the substance is present in minute quantities. When larger quantities 

 of the substance are smelt the odour appears to be penetrating, but 

 more aromatic than faecal. It also seems that after repeatedly 

 smelling the substance the nose becomes insensitive to the effect of 

 minute quantities and fails to recognize the faecal odour. 



It may be useful to refer here to the delicacy of the various 

 reactions for skatole and indole, since it is often important to 

 recognise the presence of very small quantities of these substances in 

 pathological fluids. The formation of the white insoluble nitroso- 

 derivative from skatole by the action of nitrous acid cannot be 



* The nomenclature followed is that proposed by Emil Fischer, the isomerides in 

 which the substitution occurs in the pyrrole nucleus of indole being distinguished as 

 Pr-derivatives, and those in which substitution takes place in the benzene nucleus 

 as Bz-derivatives. The hydrogen atoms of the two nuclei are numbered in accord- 

 ance with the following plan — 



CH 



HC^^CH 

 ! Bz Pr I 



HC \v^/ CH 



