Christian Friedrich Schönbein (18 October 1799 - 29 August 1868)


Christian Friedrich Schönbein in 1857
Christian Friedrich Schönbein in 1857
Image Source Wikipedia.org (German version)

Christian Friedrich Schönbein was born on 18 October 1799, in the family home at 2 Metzingen, Swabia (southern Germany) . His father was a dyer. He attended the Metzinger primary school and was just 13 when he was apprenticed to Metzger and Kaiser, a chemical and pharmaceutical firm at Böblingen where he worked thirteen hours a day. At first he suffered badly from home sickness but he persevered and soon became a practical chemist.

At 21 he underwent a chemistry exam, the only one he took in his life, and obtained a certificate from Dr Kielmeyer of Stuttgart that stated he had a good scientific and practical knowledge of chemistry. After a brief period of military conscription he moved to Dr JG Dingler's chemical products firm in Augsburg. Initially he was on fourteen days probation and if unsuitable would have been sent back "carriage paid". He clearly passed this probationary period and went on to receive board and lodging and an annual salary of between 200 to 300 florins.

He did not stay long with Dingler and was soon studying at the universities of Tübingen and Erlangen. At the latter he was a contemporary of the German chemist Justus von Liebig.

Sometime in 1826, Schönbein moved to The Cedars School, Epsom to teach mathematics and natural sciences. The school was run on Pestalozzi lines by the educational reformer, Rev. Charles Mayo.. He was paid £50 per year and provided with board, lodging and washing. Schönbein probably heard of the Epsom school from his friend Christian Friedrich Wurm who was already working there. Whilst working in Epsom Schönbein took the opportunity of visiting Scotland and London gleaning knowledge and making friends wherever he went. He developed lifelong friendships with scientists Michael Faraday, William Robert Grove and Thomas Graham.

In 1827 Schönbein left England to teach briefly in Paris and attend lectures at the Sorbonne. He met Gay-Lussac, Thénard, Biot, Dumas, Pouillett, and Brongniart. In November that year he returned to England for a short stay with a former Epsom colleague living at Stanmore, Middlesex. Whilst there he was invited to become a temporary professor of physics and chemistry at the University of Basel.

In 1832, after a lengthy period of settling in, which coincided with some local political disturbances during which Schönbein bore arms, he started publishing the first of over 364 scientific papers. By February 1834 the political situation was calmer and Schönbein was made a full professor. In July the following year he married Emilie Benz in Stuttgart with whom he had 4 daughters.

Schönbein is credited with four scientific advances:

Ozone

Schönbein noticed a distinctive odour in his laboratory whilst doing experiments on the electrolysis of water. He realised that the he had discovered a new element and coined the term 'ozone' from the Greek word 'ozein', meaning 'to smell'. Schönbein described his discoveries in publications in 1840, he later found that the smell of ozone was similar to that produced by the slow oxidation of white phosphorus and the ozone smell is the same as during a thunderstorm, indicating that ozone was in the atmosphere. Ozone is currently being used as a medical therapy and as a powerful disinfectant for water and sewage treatment.

Gun Cotton

Against his wife's wishes Schönbein occasionally experimented in the family laundry. Whilst his wife was away in 1845, he spilt a mixture of nitric and sulphuric acid which he mopped up with her cotton apron. He rinsed out the apron and hung it over the stove to dry, only to find that after a while the cloth spontaneously ignited and burned so quickly that it seemed to disappear with virtually no smoke or other by-products. He had accidentally discovered a way of producing guncotton (nitrocellulose). Schönbein recognized the possibilities as when ordinary gunpowder explodes it produces thick black smoke, which gives away the gunner's position, obscures their view of the battlefield, and produces quantities of by-products which clogs up the weapon. A crude version of nitrocellulose had been discovered in 1838 by Théophile Pelouze but he did not followed up his observations so Schönbein is widely regarded as the person who discovered guncotton. He patented his process and gave manufacturing rights to John Hall & Sons in Faversham. Unfortunately guncotton burns readily or explodes making its manufacture very dangerous and in July 1847 an explosion at the Faversham factory killed 21 workers. It took over 40 years to develop guncotton into a safe and useful mixture called cordite.

Collodion

Soluble guncotton is used in making collodion (also known as pyroxylin) which is just a solution of nitrocellulose in ether or acetone. Frenchman Louis Nicolas Menard discovered collodion but as it is based on Schönbein's process for gun cotton he must take some of the credit. During the Crimean war collodion was used for painting over a wound as a protective dressing as it dries to a thin clear film. Today it is used in lacquers, plastics, and artificial leathers and as a constituent of some 'new skin' type products.

Collodion was also used to bind light sensitive chemicals to glass photographic plates. Extra verses added to Lewis Carroll's poem "Hiawatha's Photographing" describe the process:
"..... First, a piece of glass he coated
With collodion, and plunged it
In a bath of lunar caustic
Carefully dissolved in water -
There he left it certain minutes.

Secondly, my Hiawatha
Made with cunning hand a mixture
Of the acid pyrro-gallic,
And of glacial-acetic,
And of alcohol and water
This developed all the picture.

Finally, he fixed each picture
With a saturate solution
Which was made of hyposulphite
Which, again, was made of soda. ...."
The collodion process had several advantages.
  • It was much more sensitive to light than the calotype process so reducing the exposure times from minutes to seconds.
  • Glass plates gave sharper images than with the calotype process.
  • It was much cheaper to produce photographic prints compared to the daguerreotype process.

When collodion is mixed with camphor it makes a bendable product called celluloid that was used as a base of early flexible photographic and cine films.

Fuel Cell

Schönbein discovered the principle of the fuel cell in 1838 but it was his Welsh friend Sir William Robert Grove who developed the first prototype using hydrogen and oxygen to create electricity in 1845. Development of fuel cells only took off over a hundred years later and currently much research is being carried out on their use in motor cars because they can produce power at very low pollutant levels. (Incidentally Grove, who by day was a solicitor, had acted for Schönbein as his English gun cotton patent lawyer).

Schönbein died on 29 August 1868 whilst traveling back from Baden but his scientific legacy lives on.

Major Sources:
Nature No.1596 Vol. 62 (31 May 1900)
A Dictionary of Scientists (OUP 1999)
Wikipedia
http://www.rleggat.com/photohistory/history/collodio.htm
http://people.virginia.edu/~ds8s/carroll/hia.html#EXTRA
Encyclopaedia Britannia



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Victor Yarsley
Victor Yarsley