BUNSEN, ROBERT WILHELM VON (1811-1899), German chemist, was born at Göttingen on the 31st of March 1811, his father, Christian Bunsen, being chief librarian and professor of modern philology at the university. He himself entered the university in 1828, and in 1834 became Privat-docent. In 1836 he became teacher of chemistry at the Polytechnic School of Cassel, and in 1839 took up the appointment of professor of chemistry at Marburg, where he remained till 1851. In 1852, after a brief period in Breslau, he was appointed to the chair of chemistry at Heidelberg, where he spent the rest of his life, in spite of an urgent invitation to migrate to Berlin as successor to E. Mitscherlich. He retired from active work in 1889, and died at Heidelberg on the 16th of August 1899. The first research by which attention was drawn to Bunsen's abilities was concerned with the cacodyl compounds (see Arsenic), though he had already, in 1834, discovered the virtues of freshly precipitated hydrated ferric oxide as an antidote to arsenical poisoning. It was begun in 1837 at Cassel, and during the six years he spent upon it he not only lost the sight of one eye through an explosion, but nearly killed himself by arsenical poisoning. It represents almost his only excursion into organic chemistry, and apart from its accuracy and completeness it is of historical interest in the development of that branch of the science as being the forerunner of the fruitful investigations on the organo-metallic compounds subsequently carried out by his English pupil, Edward Frankland. Simultaneously with his work on cacodyl, he was studying the composition of the gases given off from blast furnaces. He showed that in German furnaces nearly half the heat yielded by the fuel was being allowed to escape with the waste gases, and when he came to England, and in conjunction with Lyon Playfair investigated the conditions obtaining in English furnaces, he found the waste to amount to over 80%. These researches marked a stage in the application of scientific principles to the manufacture of iron, and they led also to the elaboration of Bunsen's famous methods of measuring gaseous volumes, &c., which form the subject of the only book he ever published (Gasometrische Methoden, 1857). In 1841 he invented the carbon-zinc electric cell which is known by his name, and which conducted him to several important achievements. He first employed it to produce the electric arc, and showed that from 44 cells a light equal to 1171.3 candles could be obtained with the consumption of one pound of zinc per hour. To measure this light he designed in 1844 another instrument, which in various modifications has come into extensive use—the grease-spot photometer. In 1852 he began to carry out electrolytical decompositions by the aid of the battery. By means of a very ingenious arrangement he obtained magnesium for the first time in the metallic state, and studied its chemical and physical properties, among other things demonstrating the brilliance and high actinic qualities of the flame it gives when burnt in air. From 1855 to 1863 he published with Roscoe a series of investigations on photochemical measurements, which W. Ostwald has called the "classical example for all future researches in physical chemistry." Perhaps the best known of the contrivances which the world owes to him is the "Bunsen burner" which he devised in 1855 when a simple means of burning ordinary coal gas with a hot smokeless flame was required for the new laboratory at Heidelberg. Other appliances invented by him were the ice-calorimeter (1870), the vapour calorimeter (1887), and the filter pump (1868), which was worked out in the course of a research on the separation of the platinum metals. Mention must also be made of another piece of work of a rather different character. Travelling was one of his favourite relaxations, and in 1846 he paid a visit to Iceland. There he investigated the phenomena of the geysers, the composition of the gases coming off from the fumaroles, their action on the rocks with which they came into contact, &c., and on his observations was founded a noteworthy contribution to geological theory. But the most far-reaching of his achievements was the elaboration, about 1859, jointly with G.R. Kirchhoff, of spectrum analysis, which has put a new weapon of extraordinary power into the hands both of chemists and astronomers. It led Bunsen himself almost immediately to the isolation of two new elements of the alkali group, caesium and rubidium. Having noticed some unknown lines in the spectra of certain salts he was examining, he set to work to obtain the substance or substances to which these were due. To this end he evaporated large quantities of the Dürkheim mineral water, and it says much both for his perseverance and powers of manipulation that he dealt with 40 tons of the water to get about 17 grammes of the mixed chlorides of the two substances, and that with about one-third of that quantity of caesium chloride was able to prepare the most important compounds of the element and determine their characteristics, even making goniometrical measurements of their crystals.
Bunsen founded no school of chemistry; that is to say, no body of chemical doctrine is associated with his name. Indeed, he took little or no part in discussions of points of theory, and, although he was conversant with the trend of the chemical thought of his day, he preferred to spend his energies in the collection of experimental data. One fact, he used to say, properly proved is worth all the theories that can be invented. But as a teacher of chemistry he was almost without rival, and his success is sufficiently attested by the scores of pupils who flocked from every part of the globe to study under him, and by the number of those pupils who afterwards made their mark in the chemical world. The secret of this success lay largely in the fact that he never delegated his work to assistants, but was constantly present with his pupils in the laboratory, assisting each with personal direction and advice. He was also one of the first to appreciate the value of practical work to the student, and he instituted a regular practical course at Marburg so far back as 1840. Though alive to the importance of applied science, he considered truth alone to be the end of scientific research, and the example he set his pupils was one of single-hearted devotion to the advancement of knowledge.
See Sir Henry Roscoe's "Bunsen Memorial Lecture," Trans. Chem. Soc., 1900, which is reprinted (in German) with other obituary notices in an edition of Bunsen's collected works published by Ostwald and Bodenstein in 3 vols. at Leipzig in 1904.
BUNTER, the name applied by English geologists to the lower stage or subdivision of the Triassic rocks in the United Kingdom. The name has been adapted from the German Buntsandstein, Der bunte Sandstein, for it was in Germany that this continental type of Triassic deposit was first carefully studied. In France, the Bunter is known as the Grès bigarré. In northern and central Germany, in the Harz, Thuringia and Hesse, the Bunter is usually conformable with the underlying Permian formation; in the south-west and west, however, it transgresses on to older rocks, on to Coal Measures near Saarbruck, and upon the crystalline schists of Odenwald and the Black Forest.
The German subdivisions of the Bunter are as follows:—(1) Upper Buntsandstein, or Röt, mottled red and green marls and clays with occasional beds of shale, sandstone, gypsum, rocksalt and dolomite. In Hesse and Thuringia, a quartzitic sandstone prevails in the lower part. The "Rhizocorallium Dolomite" (R. Jenense, probably a sponge) of the latter district contains the only Bunter fauna of any importance. In Lorraine and the Eifel and Saar districts there are micaceous clays and sandstones with plant remains—the Voltzia sandstone. The lower beds in the Black Forest, Vosges, Odenwald and Lorraine very generally contain strings of dolomite and carnelian—the so-called "Carneol bank." (2) Middle Buntsandstein-Hauptbuntsandstein (900 ft.), the bulk
of this subdivision is made up of weakly-cemented, coarse-grained sandstones, oblique lamination is very prevalent, and occasional conglomeratic beds make their appearance. The uppermost bed is usually fine-grained and bears the footprints of Cheirotherium. In the Vosges district, this subdivision of the Bunter is called the Grès des Vosges, or the Grès principal, which comprises: (i.) red micaceous and argillaceous sandstone; (ii.) the conglomérat principal; and (iii.) Grès bigarré principal (=grès des Vosges, properly so-called). (3) Lower Buntsandstein, fine-grained clayey and micaceous sandstones, red-grey, yellow, white and mottled. The cement of the sandstones is often felspathic; for this reason they yield useful porcelain clays in the Thuringerwald. Clay galls are common in the sandstones of some districts, and in the neighbourhood of the Harz an oolitic calcareous sandstone, Rogenstein, occurs. In eastern Hesse, the lowest beds are crumbly, shaly clays, Brockelschiefern.
The following are the subdivisions usually adopted in England:—(1) Upper Mottled Sandstone, red variegated sandstones, soft and generally free from pebbles. (2) Bunter Pebble Beds, harder red and brown sandstones with quartzose pebbles, very abundant in some places. (3) Lower Mottled Sandstone, very similar to the upper division. The Bunter beds occupy a large area in the midland counties where they form dry, healthy ground of moderate elevation (Cannock Chase, Trentham, Sherwood Forest, Sutton Coldfield, &c.). Southward they may be followed through west Somerset to the cliffs of Budleigh Salterton in Devon; while northward they pass through north Staffordshire, Cheshire and Lancashire to the Vale of Eden and St Bees, reappearing in Elgin and Arran. A deposit of these rocks lies in the Vale of Clwyd and probably flanks the eastern side of the Pennine Hills, although here it is not so readily differentiated from the Keuper beds. The English Bunter rests with a slight unconformity upon the older formations. It is generally absent in the south-eastern counties, but thickens rapidly in the opposite direction, as is shown by the following table:—
|
Lancashire and W. Cheshire. | Staffordshire. |
Leicestershire and Warwickshire. |
| (1) 500 ft. | 50-200 ft. | Absent |
| (2) 500-750 ft. | 100-300 ft. | 0-100 ft. |
| (3) 200-500 ft. | 0-100 ft. | Absent |
The material forming the Bunter beds of England came probably from the north-west, but in Devonshire there are indications which point to an additional source.
In the Alpine region, most of the Trias differs markedly from that of England and northern Germany, being of distinctly marine origin; here the Bunter is represented by the Werfen beds (from Werfen in Salzburg) in the northern Alps, a series of red and greenish-grey micaceous shales with gypsum, rock salt and limestones in the upper part; while in the southern Alps (S. Tirol) there is an upper series of red clays, the Campil beds, and a lower series of thin sandstones, the Seis beds. Mojsisovics von Mojsvar has pointed out that the Alpine Bunter belongs to the single zone of Natica costata and Tirolites cassianus.