This Austrian stamp, issued in 1973, commemorates the 50th anniversary of Fritz Pregl receiving the Nobel Prize in Chemistry (1923). Pregl, an Austrian chemist, was honored for his pioneering work in microanalysis, which revolutionized organic chemistry by enabling precise measurements of very small samples. The deep blue portrait design captures his scholarly demeanor, surrounded by inscriptions marking the jubilee. This 4 Schilling issue is a valued collectible for those interested in science-themed and Nobel Prize commemorative stamps.