Christmas chemistry: The science behind baubles

Professor Mark Lorch from the University of Hull explains the chemistry of Christmas decorations and the scientist who made these tree decorations possible.

A version of this article was originally published by The conversation (CC BY-ND 4.0)

If not for Baron Justus von LiebigChristmas can look and taste very different. Yet despite his contribution to everything from the bouillon cubes used in his sauce to the mirrors in your house, it is unlikely that you have heard of him.

The interests of the German chemist also extended to human nutrition. He became convinced that the juices coming out of cooked meat contained valuable nutritional compounds and encouraged cooks to burn the meat to seal in the juices. This turned out to be full bunkumBut 150 years later, holiday dinner chefs across the country follow his advice.

For much of the 19th century, Liebig was a giant of the scientific establishment with his fingers stuck in many cakes. He calculated the basic nutritional needs of plants and then developed the first fertilizer, for which he is known in scientific circles as the “father of fertilization”. This work eliminated reliance on animal manure to feed crops and paved the way for industrial agriculture, including piles of Brussels sprouts.

The obsession with meat juices also led him to create meat extracts in an attempt to provide a nutritious meat substitute. The extract turned out to be a pretty poor, and not particularly nutritious, alternative to meat, but Liebig Extract of Meat Company did. transform into Oxo, whose bouillon cubes find their way into so many Christmas sauces.

Mirrors and ornaments

However, Leibig’s most visible contribution to Christmas may well be hanging from his Christmas tree. Christmas trees have their roots It dates back to the Roman Saturn celebration of the winter solstices, a religious holiday involving drinking, singing and exchanging gifts, dedicated to the Roman god Saturn. Later, probably sometime in the 16th century, decorated trees were brought into homes and this German idea was popularized by Queen Victoria in the mid-19th century.

Some of the earliest reported glass tree decorations, dating back to the 16th century, were bead garlands produced by the Greiner family in Lauscha, Germany. Some 250 years later, the family was still making ornaments, and Hans Greiner became famous for his ornate glass nuts and fruits, decorated with mirrored internal surfaces.

At the time, mirrors were prohibitively expensive for most and were made by bonding a thin film of tin to glass with mercury. The process was extremely dangerous as it generated highly toxic mercury vapor, which could also leak from the mirror for decades to come. In fact, ancient mercury mirrors can be identified by mercury drops grouping at its base.

Around the same time that Hans Greiner was creating his trinkets, Liebig was developing much safer ways to make silver glassware for use in his laboratories. His method used silver nitrate, ammonia, and simple sugars. And it resulted in a fabulously smooth and crystalline silver metal film deposited on the glass.

It was soon adapted for use in other areas of science, including telescopic mirrors, and soon Greiner learned of the development and incorporated it into his ornaments. Eventually the process also led to mass-produced mirrors, which were cheap enough to make commonplace.

Shortly after Liebig developed his plating method, another German chemist modified the process. Bernhard Tollens, who turned the process into an analytical technique to identify particular chemical groups called aldehydes.

The Tollens technique has the rather beautiful side effect of quickly silvering the container in which it is transported. See a mirrored surface shape in your hands It’s a real treat, making it a favorite for chemistry lessons around the world.

The conversation
For Professor Mark Lorch

Mark Lorch is professor of science communication and chemistry at the University of Hull.

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