[L.; = dead head.]
† 1. A death’s head, a skull. Obs.
1658. R. Franck, North. Mem. (1821), 153. Fancying … he lived now in his grave, and every object a Caput Mortuum.
2. Alch. and Chem. The residuum remaining after the distillation or sublimation of any substance, ‘good for nothing but to be flung away, all vertue being extracted’ (Willis, 1681).
1641. French, Distill., i. (1651), 4. Adde the Caput Mortuum, of Vitriall, or Aqua fortis.
1662. R. Mathew, Unl. Alch., § 89. 153. Take out the Retort with the Capud.
1741. Compl. Fam. Piece, I. i. 80. Take … the Caput Mortuum of the Scull of a Man 1 Dram.
1794. R. J. Sulivan, View Nat., I. 135. Earth, or … caput mortuum … is the last element of all bodies which can be no farther altered by any art whatsoever.
3. fig. Worthless residue.
a. 1711. Ken, Edmund, Poet. Wks. 1721, II. 138. His youthful Heat and Strength for Sin engage, God has the Caput Mortuum of his Age.
1812. Examiner, 4 Oct., 633/2. The caput mortuum of the Addington administration.
1876. A. M. Fairbairn, in Contemp. Rev., June, 124. The Pietists and High Lutherans hailed it [Strauss’ ‘Life of Jesus’] as the caput mortuum of the speculative and critical school.
