readily, with formation of hydrocarbon, than the secondary compounds, 
which are partly again obtained without change. 
Kondakow and Schindelmeiser have made a more detailed 
examination of the menthyl bromide, formed by the action of phosphorus 
pentabromide or concentrated hydrobromic acid on menthol, and find 
the above statement confirmed. Of much interest is the observation, 
that the menthene which is formed from tertiary menthyl bromide, 
cannot be completely converted by Reychler's process (by the action 
of trichloro-acetic acid) into tertiary menthol. The small portion of 
the hydrocarbon which remains unattacked has a somewhat different 
odour, and also boils higher, than the ordinary menthene; it is possible 
that it represents a pseudo-menthene. 
Aldehydes. 
Citronellal. If citron ellal oxime is mixed at a much reduced 
temperature with several times its weight of about 50 per cent, sulphuric 
acid, the mixture which is at first clear, becomes cloudy (as F. Mahla^) 
observed) when left standing for several hours, and the acid liquid 
now contains a base CgH^^ON, which is formed from the oxime 
by formation of a ring with, simultaneous displacement of one atom 
of hydrogen: 
C Hg C 
c 
HCH 
HON:HC 
H,C 
CH. 
H 
HON-HC 
H^C 
C 
CH 
CH, 
CH, 
CH 
CH 
CH 
ca 
The citronellal oxime has consequently changed into a zl^^9)-oxamino- 
3 -menthene. If sodium nitrite is allowed to act on this base in the 
presence of oxalic acid in aqueous solution, the one atom of hydrogen 
of the NH • OH-group is replaced by NO, and a nitroso-oxamino- 
menthene is obtained as a crystallised compound melting at 52°. 
Under the influence of heat or dilute acids this compound is readily 
decomposed with liberation of nitrous oxide NgO, by which there is 
^) Berliner Berichte 36 (1903), 484. 
