Observations by Watson and Holmes.

Holmes’ inferences

Disciplinary Content

Mirrortown

The city refers to a mirror, which will be related at the end of the story to the mirror image of enantiomers.

“Left-hand gloves” and “right-hand gloves”

R and S enantiomers of the compound precipitated in wine (tartaric acid). These molecules are, like hands, non-superimposable mirror images in the plane.

Twin brothers

R and S enantiomers. In many cases, one of the two may be harmful to health (see the Annex)

“Liike two peas in a pod, but one had a bitter taste while the other was sweet.”

The racemic mixture, with both enantiomers: seemingly identical, but the subtlety of the spatial configuration of the substituents gives them different properties.

“his actions (Sydney’s) that embarrassed poor Marcus”

The racemic mixture that causes an unwanted effect (See the Annex for the case of thalidomide)

Marcus (good brother)

One of the two enantiomers, in this case, the one that has no harmful effect or the one that has a beneficial effect on health,, if we extrapolate it to the medical plane to be taught.

Sydney (irascible brother)

One of the two enantiomers, in this case, the one that has a harmful effect on health, if we extrapolate it to the medical plane to be taught.