Technikatörténeti szemle 19. (1992)

KÖNYVISMERTETÉS - Papers of the First „MINERALKONTOR” International Conference on the History of Chemistry and Chemical Industry (Veszprém, 12-16 August, 1991)

The DU In 1940 Beckman and his colleagues began work on what became the DU spectrophotometer (1). Beckman saw that the DC-amplifier successfully employed in the pH meter could also be used with vacuum-tube photocells. Obtaining a LTV or visible spectrum was still a very tedious process requiring special photographic plates and time-consuming calibration for wavelength and intensity. Visible spectra at least could be matched visually against standards but it was becoming clear that much information about molecules was hidden just beyond the visible in the ultraviolet. At first pH meters were part of the spectrophotometer system, reading the electrical output. But more efficient ways of doing that were soon developed and the DU (D because it was the fourth promising system) was offered to the public a year later, in 1941. And with the DU — such as with instruments involving mass spectroscopy and nuclear magnetic resonance — whole new research fields were opened up, supporting Derek de Solla Price's contention that instruments often initiate rather than simply serve scientific fields. The old world: Spectroscopy before the DU As the war in Europe intensified during 1941, pivotal events in the history of ultraviolet spectroscopy were unfolding at two neighboring academic institutions in Cambridge, Massachusetts. In April of that year Robert Burns Woodward of Harvard published his now classic paper on ..Structure and the Absorption Spectra of alpha, beta-Unsaturated Ketones" (2). Known for his prodigious reading of the chemical literature, Woodward (Figure 2) had sifted through the experimental data of more than forty publications dating back to 1914 to arrive at a correlation between molecular structure and ultraviolet absorption that would have considerable impact on how synthetic organic chemists determined the structure of molecules. The identification of unsaturation in a molecule as the structural feature that was responsible for its color was first made in 1868. By 1940 the absorption spectra of many compounds had been determined with laborious and often timeconsuming methods, and many attempts had been made to equate the results with structural features. Woodward initially focused on the alpha-beta unsaturated carbonyl character of steroidal ketones, and was able to show that „The use of a variety of solvents for the (previous) determinations... resulted in a general diffuseness of the published values". The empirical rules which he then formulated ..rigidly correlated with the extent of substitution of the carbon-carbon double bond... and the determination of (the ultraviolet absorption maximum threw) a very considerable light upon the structure of the compound." In the burgeoning field of steroid chemistry alone this result was particularly significant. Organic chemists might not have responded readily to Woodward's powerful tool if it were not for the Ninth Summer Conference on Spectroscopy and its Applications, held at MTT just three months after Woodward's work was publicly unveiled. Speaking for co-authors Howard Cary and Arnold Beckman, who were unable to attend because of wartime travel restrictions, Edward Patterson of the Arthur H. Thomas Company in Philadelphia described „A Quartz Photoelect-