The son of an architect, Hofmann began studying law and languages but was increasingly drawn to chemistry, attracted by Liebig's teaching at Giessen. In 1841 Hofmann took his doctorate with a study of coal tar. He became Privatdozent at Bonn University in 1845, but later that year he was persuaded to take up the post of first Director of the Royal College of Chemistry in London, after tenure was guaranteed as a result of Prince Albert's influence. He remained there for twenty years until he was offered professorships in chemistry at Bonn and Berlin. He accepted the latter. Hofmann continued the method of teaching chemistry, based on laboratory instruction, developed by Liebig at Giessen, and extended it to England and Berlin. A steady stream of well-trained chemists issued forth from Hofmann's tuition, concerning themselves especially with experimental organic chemistry and the industrial applications of chemistry. In 1848 one of his students, C.B. Mansfield, devised the method of fractional distillation of coal tar, to separate pure benzene, xylene and toluene, thus laying the foundations of the coal-tar industry. In 1856 another student, W.H.Perkin, prepared the first synthetic dyestuff, aniline purple, heralding the great dyestuffs industry, in which several other of his students distinguished themselves. Although keenly interested in the chemistry of dyestuffs, Hofmann did not pursue their large-scale preparation, but he stressed the importance of scientific research for success on a commercial scale. Hofmann's stimulus in this direction flagged after his return to Germany, and this was a factor in the failure of British industry to follow up their initial advantage and allow it to pass to Germany. In 1862 Hofmann prepared a dye from a derivative of triphenylmethane, which he called rosaniline. From this he derived a series of beautiful colours, ranging from blue to violet, which he patented as 'Hofmann's violets' the following year.
b. 11 September 1854 American Union, New York, USA
d. 19 July 1923 Evanston, Illinois, USA
The American skyscraper was, in the 1870s and 1880s, very much the creation of what came to be known as the Chicago school of architecture. It was the most important American contribution to the urban architectural scene. At this time conditions were ripe for this type of office development, and in the big cities, notably Chicago and New York, steeply rising land values provided the incentive to build high; the structural means to do so had been triggered by the then low costs of making quality iron and steel. The skyscraper appeared after the invention of the passenger lift by Otis and the pioneer steel-frame work of Jenney. In 1875 Holabird was working in Jenney's office in Chicago. By 1883 he had set up in private practice, joined by another young architect, Martin Roche (1855-1927), and together they were responsible for the Tacoma Building (1887-9) in Chicago. In this structure the two front façades were entirely non-load-bearing and were carried by an internal steel skeleton; only the rear walls were load-bearing. The design of the building was not revolutionary (this had to wait for L.H.Sullivan) but was traditional in form. It was the possibility of being able to avoid load-bearing outer walls that enabled a building to rise above some nine storeys, and the thirteen-storeyed Tacoma Building pointed the way to the future development of the skyscraper. The firm of Holabird & Roche continued in the following decades in Chicago to design and construct further high-quality, although lower, commercial buildings such as those in South Michigan Avenue and the McClurg Building. However, they are best remembered for their contribution in engineering