In birds, this stalk consists entirely of blood-vessels, which in the adult enclose no terminal vesicle, and fuse with the membranous linings of the skull.
Sometimes linings of enamelled iron or other material are employed, which when worn can be replaced at a far lower cost than that of a new still.
The fusion process is preferably carried out in crucible furnaces; shaft furnaces are unsatisfactory on account of the disintegrating action of the molten bismuth on the furnace linings.
For shaft linings steel rings of H or channel section supported by intermediate struts are also used, and cross-bearers or buntons of steel joists and rail guides are now generally substituted for wood.
The town formerly had a considerable manufacture of serges and shalloons, or light woollen linings, so called from Chalons-sur-Marne, France.
