When the Tin ore is contaminated with _Mundic_, that is, with _Arsenical_ and _Iron Pyrites_, it is first roasted in the _Burning House_, and then washed; by which means the Tin, which is heavy, is easily separated from the other ores, which are comparatively light. If any _Sulphuret of Copper_ be present, the same process is calculated to separate it, by thus converting it into a _Sulphate_,[108] as described at page 128. When the ore is dressed, the lord of the soil receives that portion which is his due, after which it is divided into as many _doles_ or shares, as there are adventurers; and these are measured out by barrows, an account of which is kept, in the manner of the old times, by a person who notches a stick. The manner of dressing and cleansing _Copper_ ore is nearly similar to that of Tin, except indeed that as it is raised in large masses, and is tolerably pure, it does not generally require _Stamping_, nor much washing. All these different processes furnish employment for a great number of women and children, and it is really interesting to see the dexterity and cheerfulness with which they pursue the occupation. There is, however, one practice which ought to be reformed--the burthen of the _Standard Barrow_ used in carrying Copper, and which is said to contain three hundred weight; in addition to which we must allow for the weight of the barrow itself, and that of the water held by the recently washed ore, so that it cannot be estimated at less than four hundred weight. This is an enormous burthen, which is borne by all descriptions of persons who are employed in dressing and weighing, and it has given rise to many evils. Those who work below have generally a wretched and emaciated appearance, although they seldom continue longer under ground than six hours in the twenty-four, but are relieved by a fresh corps. Pulmonary consumption may be said to be the disease to which they are more particularly liable. The names by which the Cornish mines are distinguished are usually invented by the first adventurers, and are often whimsical enough, the usual prefix, _Huel_, (always pronounced, and generally erroneously spelt, _Wheel_) signifies in the Cornish language _a hole_; while the specific name of the mine is taken from some trivial or accidental circumstance, thus _Dolcoath_ was the name of an old woman, _Dorothy Koath_, who lived upon the spot where the working of the mine commenced; _Huel Providence_ was so called from the accidental way in which it was discovered; and _Huel Boys_ from the lode having been first noticed by children who had been playing, and digging pits in imitation of shafts. By a rough calculation it may be stated that there are about 130 mines in the county, but the number is of course subject to variation; old workings being frequently given up, and new mines opened, or forsaken ones resumed.