Rosinger’s stirrer

Magnetic stirrers are pretty humdrum pieces of kit. Yet when a colleague took one to an art school a few weeks ago, the audience was so mesmerised by the tinkling flea that it took some time before they could focus on his talk.

In the 20th century, mixing reactions was increasingly a problem. Some chemists attached electric bells to the top of the flask to vibrate their flasks gently. If proper stirring was needed, they used a flail or paddle of glass or metal spun by a compressed air-turbine or electric motor (such as Emanuel Hershberg’s) clamped to the stand above the reaction. But those machines would be almost entirely swept away for routine reactions by the magnetic stirrer, the brainchild of Arthur Rosinger.

Rosinger was born in the Transylvanian town of Nagyvarad, also known as Oradea or Großwardein, the multiple names a reminder of the now-lost cultural mosaic that was much of Central Europe before the world wars. He later moved to Koloszvár (Cluj-Napoca) to study at the Royal Hungarian Franz Joszef University. His thesis was devoted to the study of the photosensitivity of bitumen, the basis of the earliest method of recording images. Rosinger would become something of an expert in colour photography. During his time in the lab he also devised a modified Soxhlet extractor with the delicate syphon, protected from breakage, inside the reservoir. He would gain a reputation as something of an inventor, although few traces of his early ideas remain.