"Organic compounds exist in which a hydrogen atom, joined to the carbon, acquires acid properties as a result of the proximity of certain functional groupings."

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Thus, it comes to pass, that a certain room in a certain old hall, where a certain bad lord, baronet, knight, or gentleman, shot himself, has certain planks in the floor from which the blood will not be taken out. You may scrape and scrape, as the present owner has done, or plane and plane, as his father did, or scrub and scrub, as his grandfather did, or burn and burn with strong acids, as his great-grandfather did, but, there the blood will still be - no redder and no paler - no more and no less - always just the same.

— Charles Dickens