— 114 — 
of the melting point 123°, 84° to 86^, 96° to 98° and 64° to 72^; 
Dihydrocarvone and carvenone also react with nitric acid, with for- 
mation of nitro -pro ducts. Isomerisation of the ketones did not occur 
in the above reactions. 
Camphor. In his last (VIII) communication on recent experi- 
ments with campho-carbonic acid, Briihl^) summarises the results of 
his entire work on this subject. Camphor 
shows in many of its derivatives the tendency to the formation of 
enol-forms. With camphor itself, and its alkyl derivatives, the ketone- 
form only occurs, but with the acid derivatives, and especially with 
campho-carbonic acid and substances allied thereto, the occurrence of 
both forms has been observed; thus, the acids and their esters react 
in non-dissociating solvents, such as ether and benzene, as keto acids 
(or esters), and in hydrolysed media (water, alcohol) as enol-bodies. 
The alkylised esters again occur only in ketone form. The nitrile of 
methyl camphocarbonic acid, the methylcyanocamphor of Haller and 
Minguin, takes both forms simultaneously. The substitution of the 
labile hydrogen atom of camphocarbonic acid, or of the two methylene 
hydrogen atoms of camphor, by organic acid radicals, increases the 
tendency to produce enolised forms; in almost all cases compounds 
are formed of the formula 
/C — COOR 
C . O . Ac. 
Pulegone. By saturating a strongly cooled solution of pulegone 
in petroleum ether with vapours of nitric oxide, or with nitrous vapours 
(from starch and nitric acid), P. Genvresse^) succeeded in producing 
a nitrosite of pulegone. The oily reaction -product which volatilises 
with difficulty with steam, becomes solid after a week, and can be 
obtained, by repeated recrystallisation from alcohol, in the form of a 
colourless compound with a silky lustre, of the melting point 68° 
to 69°. A solution of the substance in chloroform deflects the polarised 
light 23° 13' to the right (at 23°). The fact that a solution of this ^ 
body in benzene or chloroform does not discolour bromine, proves 
that the NgOg -group has become attached to the double-linking. With 
phenol and sulphuric acid, the nitrosite shows Liebermann's nitroso- 
reaction. 
^) Berliner Berichte 36 (1903), 4292. 
2) Compt. rend. 137 (1903), 494. 
