primary butyl alcoholsecondary butyl alcoholtertiary butyl alcohol several isomeric forms are known: primary butyl alcohol, 1-butanol, propylcarbinol, the butyl alcohol of fermentation; isobutyl alcohol, isopropylcarbinol, 2-methyl-1-propanol, which is narcotic in high concentrations; secondary butyl alcohol, ethylmethylcarbinol, 2-butanol; and tertiary butyl alcohol, trimethylcarbinol, 2-methyl-2-propanol, a denaturant for ethanol.