Editing Leiden (section)

=== 19th and 20th centuries ===

On 12 January 1807, a [[Leiden gunpowder disaster|catastrophe]] struck the city when a boat loaded with {{cvt|17400|kg|0|abbr=off}} of gunpowder blew up in the middle of Leiden. 151 people were killed, over 2,000 were injured and some 220 homes were destroyed. King [[Louis Bonaparte]] personally visited the city to provide assistance to the victims. Although located in the centre of the city, the area destroyed remained empty for many years. In 1886 the space was turned into a public park, the Van der Werff park.<ref>{{Cite web |url=http://www.amazing-holland.nl/assets/leiden-english.pdf |title=Leiden |website=Amazing Holland |access-date=31 December 2018 |archive-date=31 December 2018 |archive-url=https://web.archive.org/web/20181231092354/http://www.amazing-holland.nl/assets/leiden-english.pdf |url-status=live }}</ref>

In 1842, the railroad from Leiden to [[Haarlem]] was inaugurated and one year later the railway to [[The Hague]] (Den Haag) was completed, resulting in some social and economic improvement. Perhaps the most important piece of Dutch history contributed by Leiden was the [[Constitution of the Netherlands]]. [[Johan Rudolf Thorbecke]] (1798–1872) wrote the Dutch Constitution in April 1848 in his house at Garenmarkt 9 in Leiden.

Leiden's reputation as the "city of books" continued through the 19th century with the establishment of publishing dynasties by [[Evert Jan Brill]] and [[Albertus Willem Sijthoff]].<ref name="BN-History">{{cite web |url=http://www.b-n.nl/new_index.php?page=history |title=History: Leiden, city of books |publisher=Burgersdijk & Niermans |access-date=29 August 2010 |archive-url=https://web.archive.org/web/20101017011232/http://www.b-n.nl/new_index.php?page=history |archive-date=17 October 2010 |url-status=dead}}</ref> Sijthoff, who rose to prominence in the trade of translated books, wrote a letter in 1899 to [[Wilhelmina of the Netherlands|Queen Wilhelmina]] regarding his opposition to becoming a signatory to the [[Berne Convention for the Protection of Literary and Artistic Works]]. He felt that international copyright restrictions would stifle the Dutch publishing industry.<ref name="Publishers-Circular-1899">{{cite web |url=https://books.google.com/books?id=IGtNAAAAYAAJ&q=Albertus+Willem+Sijthoff&pg=PA597 |title=The Netherlands and the Berne Convention |page=597 |work=The Publishers' circular and booksellers' record of British and foreign literature, Vol. 71 |publisher=Sampson Low, Marston & Co. |access-date=29 August 2010 |year=1899 |archive-date=18 April 2021 |archive-url=https://web.archive.org/web/20210418074653/https://books.google.com/books?id=IGtNAAAAYAAJ&q=Albertus+Willem+Sijthoff&pg=PA597 |url-status=live }}</ref>

Leiden began to expand beyond its 17th-century moats around 1896 and the number of citizens surpassed 50,000 in 1900. After 1920, new industries were established in the city, such as the [[canning]] and metal industries. During [[World War II]], Leiden was hit hard by Allied bombardments. The areas surrounding the railway station and Marewijk were almost completely destroyed.

The University of Leiden has been the site of many discoveries, including [[Snell's law]] (by [[Willebrord Snellius]]), and
the [[Leyden jar]], a capacitor made from a glass jar, invented in Leiden by [[Pieter van Musschenbroek]] in 1746. Another development was in [[cryogenics]]: [[Heike Kamerlingh Onnes]] (1913 [[Nobel Prize in Physics]]) liquefied [[helium]] for the first time (1908) and later managed to reach a temperature of less than one degree above the [[absolute zero|absolute minimum]]. [[Albert Einstein]] also spent some time at Leiden University during his early to middle career.