If of glass, they are usually impressed in the mold; if of porcelain, they are painted on the ware before burning.
A tube with a foot, and with horizontal marks at varying hights to indicate quantity of contents.
An apparatus in which a solution is allowed to trickle over a large extent of surface, during which it is exposed to a current of air.
This is adopted in the salt-works of Montiers, in the Tarantaise, Switzerland, where brine having 1.83 percent of saline matter is condensed to such a degree of saturation as to be profitably evaporated by boiling.
It is trickled over fagots of thorns placed in frames, and acquires a density of 22 per cent.
Another plan is to let it trickle over suspended ropes upon which it crystallizes and is broken off. The ropes last twenty-five years; the fagots, seven years.
Vinegar is manufactured by exposing a large surface to oxidation in a similar man