This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Chelae Cancrorum Pharm. Lond. Crabs-claws: the black tips of the claws of the cancer marinus or common sea crab.
This testaceous matter, levigated into an impalpable powder, is made use of for absorbing acidities in the first passages, and makes the basis of the compound absorbent powders of the shops: to four parts of the prepared claws, the college of London joins one part of prepared red coral and one of chalk. All these three ingredients consist of the same calcareous earth: how far any of them is superiour, as a medicine, to the others, or any composition of them to any one of the three separately, does not appear. The distinguishing characters of this kind of earth are, its being convertible, by calcination with a strong fire, into quicklime; its not perfectly vitrefying with a moderate proportion of vitreous fluxes, but rendering the flux or glass opake and white; its being dis-soluble in all acids except the vitriolic, and precipitable by this last from the others.
(a) In notis ad Poterium, p. 483.
Linimentum camphorae Ph. Lond.
Ol. campho-rat. Ph. Ed.
Chelae canc. praeparatae Ph. Lond.
Pulv. e chelis cancr. comp. Ph. Lond.