BUNSEN, ROBERT WILHELM (1811-99). A distinguished German chemist. Be entered the University of Heidelberg and devoted himself to the study of geology, chemistry, and physics. He afterwards continued his studies in Paris. Berlin. and Vienna. After having held the post of professor in Cassel, ..Marburg. and Breslan, successively, lie was, in 1852, appointed to the chair of chemistry at the University of Heidel berg, where he remained until 1859, when he re tired franc active service. Bunsen's discoveries have formed important contributions to the progress of science in the latter part of the Nineteenth Century. llis discovery jointly with Kirehhotr, of the method of spectrum analysis, has led to the discovery of the alkali metals, czesi um and rubidium, and, more recently, of a num ber of other elements; with the aid of the spectroscope we are enabled further to analyze the fixed stars by analyzing the light we receive from them and ascertaining the lines character istic of the several elementary substances com posing the visible universe. Bunsen's flame tests (see ANALYSIS and FLAME) have formed another method in analytical chemistry, remarkable for its neatness and simplicity; the flame reactions are usually observed with the aid of the well known burner of Bunsen's invention, which furnished a smokeless, non-luminous flame of high temperature; the principle of the Bunsen burner is now extensively utilized in the house hold for cooking purposes. Bunsen also carried out a series of interesting researches on the double cyanides; and the cacodyl (q.v.) groups discovered by him soon after Wiihler and Liebig had discovered the benzoyl group, served to con firm the idea that the nature of an organic com pound depends upon the radicals of which it is composed—one of the fundamental principles of modern organic chemistry. Ile further de
vised a process for making the metal. magnesium on a large scale and showed how to obtain an exceedingly brilliant light by burning magne sium wire; discovered the fact that hydrated oxide of iron is an excellent antidote for arsenic poisoning. etc. Only a few of his more impor tant contributions to physical chemistry can be mentioned here. Ile investigated the absorption of gases by liquids at different temperatures and under different pressures; he showed that the melting temperature of substances which, unlike water, expand during the change from the solid to the liquid state, rises with increase of external pressure; he studied the chemical distribution of a given gas between two other gaseous sub stances, when exploded with a mixture containing an excess of either; invented the ice-calo•im eter, which is often indispensable in thermo chemical determinations: jointly with Roscoe, he adapted John W. Draper's a•tinometer for use in work of precision. and, by the use of the improved instrument, carried out, together with Roscoe, a series of important photo-chemical measure ments. He invented also the filte•-pump, a photometer, a galvanic cell which is extensively used in physical laboratories, and other useful apparatus. Among his publications may be mentioned: GaSOIlletrische Mcthoden (1857); Chemischc Analy.se (lurch Spektralbeobachtuny•n (jointly with Kirchhoff, 1861); and Elam men reaktionea (1880).