The substance, known in commercial language by the name of _White Lead_, has received at different times, very various appellations, in consequence of the fluctuating opinions which have prevailed respecting its composition. Thus it has been successively styled a _sub-acetate_, an _oxide_, and a _sub-carbonate_; of which the last is unquestionably the correct name. In the large way it is prepared by exposing sheets of metallic lead to the fumes of vinegar. The sub-carbonate so produced appears as a white, brittle, and scaly substance, on the surface of the lead; which is scraped off, and afterwards ground in mills fitted for the purpose. Formerly, it was ground dry, and the workmen suffered severely from the operation; it is now ground in water, and the sub-carbonate is afterwards dried in earthen pans placed in stoves, heated by means of flues; still, however, persons employed in grinding white lead, as well as painters[375] who are constantly using it, occasionally suffer severely, from the want of cleanliness in not washing their hands before eating, by which some of the white lead is introduced into the stomach with their food. LITHARGE. _Semi-vitrified Oxide of Lead._ This is a yellow protoxide of lead, which has been melted, and left to crystallize by cooling. It is in the form of small reddish, or yellowish scales, which are brilliant and vitrified. Its character is so peculiar that it cannot easily be mistaken. It is employed for various purposes in the arts, and is the saturnine preparation more usually selected for the purpose of removing acidity from wines, as above related. When treated with a muriatic salt, and submitted to a high temperature, a _muriate of lead_ is produced, of a bright yellow colour, the brilliancy of which may be much heightened by grinding it as usual with oil. In this state it forms the pigment known by the name of _Turner’s yellow_, or _patent yellow_.[376] It is very poisonous. RED LEAD. _Minium._