Jean Timmermans University
of
Brussels
Brussels, Belgium Tronsloted by Ralph E. Oesper Universitv of Cincinnati Cincinnati, Ohio
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Walther Spring (1848-1911)
I n the century which roughly preceded the present era, Belgium produced three chemist,^ who acquired international fame, namely, Stas, Spring, aud Swarts. Stas, a native of Louvain, was trained primarily a t Paris under Dumasl who put his brilliant student on the path which he followed through most of his chemical career, t,he precise determination of atomic weights.' Spring and Swarts came later; the former was a student at Liege, the latter a t Ghent,, but they both went to Germany for their higher training. Spring's father was of Bavarian extraction. He was on the medical faculty a t Liege and later became Rector of that university. The son Walther held the chair
Wollher Spring
of general chemistry a t Liege for many years. He was a brilliant teacher and made a deep impressiou on his students, hut he attracted but few disciples because he became a misanthrope a t an early age and preferred to work alone in his laboratory. Because of his manual skill, he was able to carry out experiments which a t that time were technically too difficult for most chemists. Consequently, his scientific works were marked by great originality.2 From among his most remarkable accomplishments, note should be taken first of all of his investigations on the behavior of solids subjected to extreme pressures of the order of thousands of atmospheres per square centimeter, pressures which a t the end of the 19th century broke all records. I n this way he showed that it is possible for metals to diffuse into each other if placed in intimate contact a t ordinary
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temperatures and then pressed together. For example, copper and zinc form an intermediate region brass, a typical example of a solid solution. This was established a t a time when van't Hoff had not yet popularized this concept. If analogous experiments are conduct,ed ~ ~ i materials th stemming from silicious rocks for instance, hut without taking the precaution to remove the traces of air, humidity, or other impurities which separate the fragments being studied, a prolonged compression transforms the mass into au agglomerate of schist, whose leaflets are separated by t,hin layers of foreigu elements. Having thus discovered the mode of formatiou of certain typical rocks of the Ardennes region, Spring undertook a study of the waters of the Meuse River, which flows through the city of Liege. For more t,han a year he followed the flow day by day, noting the particularities which it presented. The water was sometimes green, sometimes blue, and sometimes hrown, and this succession of colors led him to the quest,ion, what is the color of pure water? To arrive a t the answer, it obviously became necessary to eliminate all traces of suspended matter. To obtain optically "empty" water, Spring used two procedures. I n the first he mixed equivalent amouuts of ammonium hydroxide solution with a solut,ion of aluminum chloride. The resulting colloidal hydrous alumina settled in time and carried down with it all of the suspended impurities. He assured himself of the optical purity of the water treated in this manner by passing a strong beam of light through the clarified water. Observed laterally, the beam was quite visihle in the surrounding air because of the illumination of the suspended particles (Tyndall's effect) but it was completely invisible in the liquid. He arrived a t t,he same result in his second procedure by a t t r a c h g the electrically charged particles toward the poles of an electromagnet. Such optically empty water is practically colorless, but if it is observed through a layer ten meters long, it is found to be bluish. This finding was later confirmed by studying the absorption spectrum, a technique which was not yet in use at the t,inie Spring carried out his investigation of this iut.eresting problem. He applied his clarification methods also t,o solutions of salts of the alkali and the alkaline earth metals. He found that the blue color remains intact; but if the salt hydrolyses, the solutions tend toward the green even though the salt itself is colorless. Finally, by
