New work now began to press upon Dumas; his energy and his administrative powers were demanded by the State. Elected a member of the National Assembly in 1848, he was soon called by the President of the Republic to office as Minister of Agriculture and Commerce. He was made a senator under the second empire. He entered the municipal council of Paris about 1854, and was soon elected to the presidency. Under his presidency the great scheme for providing Paris with spring-water carried by aqueducts and tunnels was successfully accomplished; many improvements were made in the drainage of the city; the cost of gas was decreased, while the quality was improved, the constancy of the supply insured, and the appliances for burning the gas in the streets were altered and rendered more effective. Nominated to succeed Pelouze as Master of the Mint in 1868, Dumas held this honourable and important position only until the Franco-German war of 1870. Since that date he has relinquished political life; but as Permanent Secretary of the Academy Dumas now fills the foremost place in all affairs connected with science, whether pure or applied, in the French capital. In the work of these two chemists, Liebig and Dumas, we find admirable illustrations of the scientific method of examining natural appearances. In the broad general views which they both take of the phenomena to be studied, and the patient and persevering working out of details, we have shown us the combination of powers which are generally found in separate individuals. Dumas has always insisted on the need of comparing properties and reactions of groups of bodies, before any just knowledge can be gained as to the position of a single substance in the series studied by the chemist. It has been his aim as a teacher, we are assured by his friend, Professor Hofmann, never to present to his students "an isolated phenomenon, or a notion not logically linked with others." To him each chemical compound is one in a series which connects it directly with many other similar compounds, and indirectly with other more or less dissimilar compounds. Amid the overwhelming mass of facts which threaten nowadays to bury the science of chemistry, and crush the life out of it by their weight, Dumas tracks his way by the aid of general principles; but these principles are themselves generalized from the facts, and are not the offspring of his own fancy.