Found at the place from whence they take their name in the county of Derby, where there are a great number of warm springs, which, according to Dr. Short, acquire their heat by passing through a bed of lime, and what he calls croil atone. The water of the bath, and all the other tepid springs, is exceedingly clear, has no steam except in cold weather, and does not throw up bubbles: it is about a drachm in the pint lighter than common water.

A gallon of this water contains about thirty-seven or thirty-eight grains of solid matter, twelve or thirteen grains of which are sea salt, with vitriolated magnesia, the rest calcareous earth, which after calcination, contained some particles attracted by the loadstone. This water seems, therefore, to be a light chalybeate of a tepid temperature, containing but a small portion of solid matter, and is used in the diseases for which Bristol waters have been recommended; externally for the gout, rheumatism, and other complaints, where a tepid bath has been found serviceable. It is drunk from one to four or five pints in the day. Matracium. See Curcurbita. Matres. The two membranes of the brain, the ia and dura mater, supposed to be the origin of all the other membranes. (See Dura mater.) In botany, the artcmisia is the mater herbarum; in chemistry quicksilver is the mater metallorum.