ACHARD, CARL FRANZ, a Prussian chemist, born at Berlin, in 1754, who is chiefly known now by his process for extracting sugar from beet-root, in which Margraff had before detected its existence. In 1800 the French Institute voted him thanks for his paper, but considered his process of little value; until it was taken up by Napoleon in 1812, and tried at Rambouillet; since which it has been extensively carried on in France; but it is doubtful if it can ever compete with the produce of the sugar-cane, in a free market, though the sugar manufactured from it is very white, and belongs to the same kind of sugar as that from the sugar-cane. His other works are physico-chemical experiments on the adhesion of different bodies. Achard died in 1821.