Antwerp invention perfected measurement of sugar content

Until 31 January, you can admire a selection of UAntwerp’s rich academic heritage in the Stadscampus library. The occasion is the university’s 20th anniversary and the retirement of driving force Marc Demolder. One of the showpieces is Julien De Puydt’s polarimeter, a unique piece of Antwerp design for measuring sugar content in sugar beets.  

 

From cane to beet 

 

At the Verhalenvertellers (Storytellers) exhibition, you can admire Julien De Puydt’s polarimeter. The polarimeter gave the sugar industry in our country a strong boost and put Antwerp on the map as an import and export port and sales centre for sugar. ‘Until 1800, cane sugar had come from the overseas territories,’ says Emeritus Professor of Pharmaceutical Sciences Hendrik Deelstra. ‘But the Napoleonic wars put a stop to this. As the economic blockades drove up the price of cane sugar, beet cultivation in our country emerged, especially in Hageland and Haspengouw.’ 

Chimiste départageur 

 

‘Determining the price of sugar beets based on their sugar content was a complex problem,’ Hendrik continues. ‘To balance the different interests of the beet growers, manufacturers and sellers, in 1879 a committee designated Julien De Puydt and Edmond Van Melckebeke as chimistes départageurs, independent experts that were to mediate between the three parties. Having previously worked as an engineer in sugar factories around Bergen, De Puydt had already spent five years in Antwerp as a sugar expert. Van Melckebeke had trained as a pharmacist and doctor of natural sciences, and owned a big research lab in Antwerp. He was also very active in the Société de Pharmacie d’Anvers, the oldest pharmacist association in Belgium.’ 

Model with three tubes 

 

In 1887, La Sucrerie belge (the journal of the Belgian sugar industry), published a call to debate the best commercial method to analyse the sugar content of sugar beets. ‘Until then, the sugar content had always been determined using rather inaccurate densitometers,’ Hendrik explains. ‘The polarimeter, an invention by François Arago that measures the angle of rotation of polarised light through an optically active substance, turned out to be much more accurate. As the device wasn’t commercially available yet, De Puydt designed his own polarimeter and had it manufactured around 1870 by the Berlin company Schmidt & Haensch. What sets De Puydt’s polarimeter apart from other models is its three tubes, which made quicker and comparative measurements possible. Using a polarimeter would end up being the internationally accepted method for the analysis of the sugar content of beets.’ 

Nominate a new object 

 

‘The specimen at the exhibition was used in Van Melckebeke’s laboratory for years,’ says Daniël Ermens, curator of the exhibition. ‘His great-grandson donated it to the SIWE support centre for industrial scientific heritage, which eventually passed it on to UAntwerp. It’s a nice example of scientific research in Antwerp in the period preceding the founding of the university. And we have nineteen other items with great backstories, including one of the first iron lungs, Karel Van Isacker’s Torpedo typewriter, a microfilm reader, one of the first kidney dialysis devices, a silver halo hat from Germany dating back to 1890, a llama skeleton, etcetera. This exhibition is our way of establishing a dialogue with the academic community and, by extension, with anyone who’s interested in heritage. And we invite every visitor to complete the story by nominating a 21st item in addition to the 20 items shown.’