GUILLAUME

See also:

• FRANCOIS (1558-1614)

FRANCOIS

See also:

• GUILLAUME FRANCOIS ROUELLE (1703–1770)

ROUELLE (1703–1770)  , French chemist, was born in 1703 at Mathieu, near Caen . He started as an apothecary, but in 1942 he was appointed experimental demonstrator of chemistry at the Jardin du Roi in Paris, where he was especially influential and popular as a teacher, numbering Lavoisier and J . L . Proust among his pupils . Many stories are told of the vivacity and enthusiasm with which he lectured, of the absent-mindedness which sometimes led him, forgetting that his pupils could not hear what he was saying, to continue his explanations while he was out of the classroom looking for some piece of apparatus, and of the vigorous tirades, generally culminating in the epithet " plagiaire," in which he used to indulge against men with whom he disagreed (Hofer, Hist. de la chimie, ii . 378) . His most important achievement was to define " salts "—a term formerly used in the most loose and indeterminate way—as the compounds formed by the union of acids and bases, and further to distinguish between neutral, basic and acid salts . Other subjects on which he published papers were the inflammation of turpentine and other essential oils by nitric acid, and the methods of embalmment practised by the Egyptians . He died at Passy on the 3rd of August 1770 . He is known as Rouelle the elder, to distinguish him from his younger brother and assistant, HILAIRE MARIN (1718–1779), who, on his resignation In 1768, succeeded him as demonstrator at the Jardin du Roi .