It is then oxidized to anthraquinone by means of sodium dichromate and sulphuric acid in leaden vats, steam heated so that the mixture can be brought to the boil.
In the process employed at the Worcester Works in the Transvaal, the liquors, containing about 150 grains of gold per ton and from 0.08 to o 01% of cyanide, are treated in rectangular vats in which is placed a series of iron and leaden plates at intervals of 1 in.
In 1701, New York, seeking another claim, obtained from the Iroquois a grant to the king of England of this territory which they claimed to have conquered but from which they had subsequently been expelled, and this grant was confirmed in 1726 and again in 1744 About 1730 English traders from Pennsylvania and Virginia began to visit the eastern and southern parts of the territory and the crisis approached as a French Canadian expedition under Celeron de Bienville took formal possession of the upper Ohio Valley by planting leaden plates at the mouths of the principal streams. This was in 1749 and in the same year George II.
From 1776 to 1780 two depots for military stores and a workshop for the Continental army were maintained, and the leaden statue of George III., erected in Bowling Green, New York City, in 1770, and torn down by citizens on the 9th of July 1776, was cut up and taken to Litchfield, where, in the house (still standing) of Oliver Wolcott it was melted into bullets for the American army by Wolcott's daughter and sister.