These are aldehydes in which the distinctively aldehyde hydrogen has been replaced by a radical. They thus bear a relation to aldehydes similar to that of ethers to alcohols.

Alcohol, R - O - H

Aldehyde,

Ether, R - O - R

Ketone,

They may also be regarded as compounds of carbonyl with two radicals, instead of with one radical and H as in aldehydes, or one radical and hydroxyl like the acids of this series.

Hypnone.1 - Phenyl-methyl-acetone, or acetophenone, C6H5 (CO)(CH3).

Characters. - Below 60° or 70° it forms white needles, but above these temperatures it occurs as a liquid with a powerful ell of bitter almonds and orange. Preparation. - By oxiding ethyl-benzene by chromic acid in presence of (cetic acid, or by distilling a mixture of acetate and benzoate of calcium. Dose. - .05- .015 gm. Administration. - It is mixed with gelatine and enclosed in gelatine capsules.

Action. - It is a powerful hypnotic, and may be used instead of chloral or paraldehyde. It appears to be free from danger.

Uses. - To produce sleep. It is said to be especially useful in alcoholism.

Inconvenience. - It causes an unpleasant smell of acetone in the breath which annoys patients.

1This name has been given by its introducers, Dujardin-Beaumetz and Bardet.