( 462 ) 
that the nitration of the methyl ester differs somewhat from that 
of the acid. Whilst the negativeness of the benzene nucleus is 
increased by the chlorine, that of the side chain is diminished by 
the introduction of methyl. 
It is also known in the chemistry of aromatic substances that 
the groups in the ortho-position exercise a greater influence on each 
other than others and it has been shown that this influence depends 
not so much on their nature as on their position, so that the same 
phenomenon, such as the counteracting or preventing of a reaction 
of one of the groups by the other, may be caused both by a 
negative and a positive one; phenomena of this kind, so-called 
sterical obstacles, might occur here and should not be lost sight of. 
A score of unknown compounds wanted for, or produced during 
the research and which also had to be made in different ways for 
the purpose of identification are described in the dissertation. 
Looking at the results obtained, it is first of all shown that the 
nitrating process (with hydrogen nitrate at zero) gave with the free 
chloro-benzoic acids results not greatly differing from those obtained 
by other methods. The chief products were at all events the same 
but it has not been ascertained whether their relative amount was 
the same. Ortho-chlorobenzoic acid gave a second mono-nitroderi- 
vative which has not been further investigated, but not a di-nitro- 
derivative such as obtained by HUBNER on gently warming with 
fuming nitric acid. 
The methyl esters yielded as chief product the esters of the same 
nitro-acids which were obtained from the free acids; the bye-products 
and their propertions have not been further investigated and no 
mention is made of the influence of temperature on the nitration. 
The results obtained in the nitration of amides and methylamides 
at zero agree with those obtained by TAVERNE with benzamide, 
phenylacetamide, phenylpropionamide and their methylderivatives in 
so far as the position occupied by the nitro-group is the same as 
in the chief product of nitration of the free acids. But TAVERNE 
obtained from benzamide only the m-nitroderivative, whilst benzoic 
acid yielded both the m- and o-derivatives; from phenylacetamide 
and phenylpropionamide only the p-derivative was obtained whilst 
the acids gave both the p- and o-compounds just as the methyl and 
dimethylamides. 
The time required for complete nitration seems to differ greatly. 
It seems as if the amides and methyl-amides are nitrated less rapidly 
than the corresponding acids and that there exists even a difference 
between the derivatives of the three isomeric chloro-benzoic acids. 
