The weight of the molecule has an influence in the alcohols and acids of the fatty series; for instance, ethyl, propyl, butyl, and amyl alcohols show as they increase in carbon a regular increase in toxic power; the narcotic actions of sodium propionate, butyrate, and valerianate also increase with the rising carbon. Nitrogen in the triad condition in the amines is far less poisonous than in the pentad condition. Bamberger[34] distinguishes two classes of hydrogenised bases derived from α and β naphthylamine, by the terms “acylic” and “aromatic.” The acylic contains the four added hydrogens in the amidogen nucleus, the aromatic in the other nucleus, thus [34] _Ber._, xxii. 777-778. CH CNH₂ /\ /\ / \C/ \ CH | | | CH | | | CH | | | CH \ /C\ / \/ \/ CH CH α Naphthylamine. CH CH /\ /\ / \C/ \ CH | | | CNH₂ | | | CH | | | CH \ /C\ / \/ \/ CH CH β Naphthylamine. CH CH₂ /\ /\ / \C/ \ CH | | | CNH₃ | | | CH | | | CH₂ \ /C\ / \/ \/ CH CH₂ Acylic tetrahydro-α Naphthylamine. CH₂ CH /\ /\ / \C/ \ CH₂ | | | CNH₂ | | | CH₂ | | | CH \ /C\ / \/ \/ CH₂ CH Aromatic tetrahydro-β Naphthylamine. The acylic β tetrahydro-naphthylamine, the β tetrahydroethylnaphthylamine, and the β tetrahydromethylnaphthylamine all cause dilatation of the pupil and produce symptoms of excitation of the cervical sympathetic nerve; the other members of the group are inactive. § 24. The result of replacing hydrogen by alkyls in aromatic bodies has been studied by Schmiedeberg and others; replacing the hydrogen of the amidogen by ethyl or methyl, usually results in a body having a 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, but when two hydrogens of the amidogen group are replaced by two methyls thus-- HO /\ / \ | |NH₂ | | | | \ / \/ HO /\ / \ | |N(CH₃)₂ | | | | \ / \/ 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.