but- Also butyro-.
Four-carbon chains of atoms.
[The first element of English butryic, from Latin butyrum, butter.]
The first chemical compound named from this Latin source was butyric acid, C3H7COOH, a colourless organic acid, so named because it was found in rancid butter. Names for other four-carbon compounds have since been created, such as the hydrocarbons butane, butadiene, and butylene, and the organic alcohol butanol. The adjective is butyl, in reference to the radical C4H9—, as in butyl rubber and in butyl acetate, an important solvent in lacquers.
The longer form butyro- is now relatively uncommon, but appears, for example, in butyrophenone, one of a small group of tranquillizers used to relive symptoms of serious psychiatric disorders. A butyrometer is an instrument for estimating the percentage of butter-fat in milk.