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Classic kit: Allihn condenser


Classic Kit
Allihn condensers are still in use today

© GLASSCO LABS
One seldom sees grown-ups in public blowing bubbles. It just isn't done. But if the adult is accompanied by a child then any inhibition they might have had is removed and bubbles, rightly, become the source of giggles and laughter. After all, is there any more delightful toy than an evanescent, seemingly weightless, and multicoloured bubble?

For a time, though, bubbles were not just toys, but the object of serious investigation. Everyone who was anyone worked on them. Think Faraday, Young, Rayleigh. Joseph Plateau, the Belgian physicist who first discovered the persistence of our vision that is essential to the illusion that is cinema, spent many years playing with bubbles and formulated a series of empirical rules that govern their behaviour. 

Nowadays, bubbles and foams are everywhere in our lives, from the insulation in our houses and the padding in our shoes, to the froth on our cappuccino, but apart from the odd clown and entertainer there is only one profession that is paid by the bubble: glassblowing. Few chemists today ever get a chance to blow glass, but open any textbook on glassblowing and you'll read that one of the first hurdles is mastering the art of blowing glass bubbles - a crucial step for making round bottom flasks and any circular openings that make way for junctions and connexions. A classic exercise for an apprentice is to blow a series of identical and equally spaced bubbles along the length of a piece of tubing, a job that takes breath control, steady hands and patience. Fittingly, this fundamental stage in the education of a glassblower is enshrined in a device, the Allihn condenser.

Felix Richard Allihn is a mysterious figure who left a trail of useful contributions, but almost no personal details. He was born in Germany around 1854 and may have been the son of the prolific philosopher Friederich Heinrich Theodor Allihn (1811-1885). Felix may have studied in nearby Leipzig but what little evidence there is, is at best circumstantial. He would later publish a paper on sugars with Paul Degener, an organic chemist who had obtained his doctorate in Leipzig in 1879 with Hermann Kolbe's right hand man and cousin Ernst von Meyer. Kolbe, the irascible but charismatic professor of organic chemistry in Leipzig, would regularly vent spleen at those with new-fangled ideas, like the ring structure of benzene, at odds with his own. In spite of this quixotic conservatism, and what seems to have been a vile temper, over 1000 students went through his labs. Was Allihn among them?

Classic Kit
In the late 1870s Allihn wrote a couple of papers in organic chemistry, and in 1879 he was inducted into the German Chemical Society. He appears in the journal Berichte  as assistant at the Institute of Agricultural Physiology in Lindenau, a village to the east of Leipzig. And in 1882 Allihn published a gravimetric method for the determination of reducing sugars that was widely adopted. The work seems to have been carried out in Leipzig, but this time from Ostwald's physical chemistry labs. 

But by the end of the decade his research days were over. He moved to Berlin where he now worked for the leading instrument maker Warmbrunn, Quilitz & Co. developing apparatus. There was an improved Bunsen burner, a filter with a fritted Hirsch funnel and a bulbous suction flask.  

But there was also a condenser for use in analytical extractions utilising the newly invented Soxhlet extractor (see Chemistry World, September 2007, p77). His concern in the paper announcing the device was that a conventional straight-walled Liebig-type condenser (see Chemistry World, September 2009, p69) was ineffective for low boiling solvents like ether. Allihn's solution was simple - to increase the internal surface area by decorating the inner tube with a series of spherical bubbles to maximise the thermal contact with the cooling water. It was a cheap modification that improved the performance of the condenser substantially. Allihn noted at the end of the paper that the device was obtainable from Warmbrunn, Quilitz & Co., the firm of which he eventually became a director. The condenser would remain in its catalogues until the company vanished around the time of the second world war.  

Allihn's last papers are devoted to a peculiar shift in calibration that mercury thermometers made of Jena glass would undergo if left undisturbed for long periods.  

Allihn died on 29 September 1915, his passing briefly noted in Berichte. In his condenser, however, his bubbles remain forever suspended, as if in a reliquary of glass. The next time you sip champagne, think bubbles. Think Allihn. 

Andrea Sella is a lecturer in inorganic chemistry at University College London, UK 

References

F Allihn, Fresenius Z. Anal. Chem., 1886, 25, 36