The advance in chemistry for which he is most famous was the discovery of carbonic acid gas, and the first steps in the recognition of the various kinds of gases. Previous to his discovery chemists had no clear perception of a distinction between the various gases; they reckoned them all as air. Geber and other predecessors of Van Helmont had observed that certain vapours were incorporated in material bodies, and they regarded these as the spirits, or souls, of those bodies. Van Helmont was the first actually to separate and examine one of these vapours. He tracked this gas through many of the compounds in which it is combined or formed: he got it from limestone, from potashes, from burning coal, from certain natural mineral waters, and from the fermentation of bread, wine, and beer. He found that it could be compressed in wines and thus yield the sparkling beverages we know so well. He also observed that it extinguished flame, and asphyxiated animals. He alludes to other kinds of vapour, but does not precisely define them. The carbon dioxide he named “gas sylvestre.” This was the first use of the term gas. “Hunc spiritum, hactenus ignotum, novo nomine gas voco.” (I call this spirit, heretofore unknown, by the new name gas.) What suggested this name to him is not certain. Some have supposed that it was a modification of the Flemish, _geest_, spirit; by others it is traced to the verb _gaschen_, to boil, or ferment; and by many its derivation from chaos is assumed. His physiology was a modification of that of Paracelsus. An Archeus within ruled the organism with the assistance of sub-archei for different parts of the body. Ferments stirred these archei into activity. In this way the processes of digestion were accounted for. The vital spirit, a kind of gas, causes the pulsation of the arteries. The Soul of Man he assigned to the stomach. The exact locality of this important adjunct was a subject of keen discussion among the philosophers of that age. Van Helmont’s conclusive argument for the stomach as its habitation was the undoubted fact that trouble or bad news had the effect of destroying the appetite. GLAUBER John Rudolph Glauber, who was born at Carlstadt, in Germany, in 1603, contributed largely to pharmaceutical knowledge, and deserves to be remembered by his many investigations, and perhaps even more for the clear common sense which he brought to bear on his chemical work. For though he retained a confident belief in the dreams of alchemy, he does not appear to have let that belief interfere with his practical labour; and some of his processes were so well devised that they have hardly been altered from his day to ours.