§ 24 .] TOXIC ACTION AND CHEMICAL COMPOSITION. 31 
more or less pronounced narcotic action. The rule is that methyl is 
stronger than ethyl, but it does not always hold good ; ortho-amido- 
phenol is not in itself poisonous, blit when two hydrogens of the 
amidogen group are replaced by two methyls thus— 
HO 
HO 
nh 2 
N(CH 3 ) 2 
\y 
\/ 
the resulting body has a weak narcotic action. 
It would naturally be inferred that the replacement of the H in the 
hydroxyl by a third methyl would increase this narcotic action, but this 
is not so : on the other hand, if there are three ethyl groups in the same 
situation a decidedly narcotic body is produced. 
The influence of position of an alkyl in the aromatic bodies is well 
shown in ortho-, para-, and meta-derivatives. Thus the senior author 
proved some years ago that, with regard to germicidal properties, ortho- 
cresol was more powerful than meta- ; meta-cresol more powerful than 
para-. So again ortho-aceto-toluid is poisonous, causing acute nephritis ; 
meta-aceto-toluid has but feeble toxic actions, but is useful as an anti¬ 
pyretic ; and para-aceto-toluid is inactive. 
In the trioxybenzenes, in which there are three hydroxyls, the toxic 
action is greater when the hydroxyls are consecutive, as in pyrogallol, 
than when they are symmetrical, as in phloroglucin. 
OH 
OH 
OH 
/\ 
V 0H 
HO ^ OH 
Pyrogallol. 
Phloroglucin. 
The introduction of methyl into the complicated molecule of an 
alkaloid often gives curious results : thus methyl strychnine and methyl 
brucine instead of producing tetanus have an action 011 voluntary muscle 
like curare. 
Benzoyl-ecgonine has no local anaesthetic action, but the introduction 
of methyl into the molecule endows it with a power of deadening the 
sensation of the skin locally ; on the other hand, cocethyl produces no 
effect of this kind. 
Crum Brown and Fraser 1 have suggested that there is some relation 
between toxicity and the saturated and non-saturated condition of the 
molecule. 
Hinsberg and Treupel have studied the physiological effect of 
1 Journ. Anal, and Phys., ii. 224. 
