The Horse Chestnut, and how it changed the world

In school logbooks from all over England, if you carefully look through the records for 1917 and 1918, you will find letters of thanks from the Director of Propellant Supplies for horse chestnuts gathered by schoolchildren and sent in to the local government offices.

Sadly, despite the many goey green images this manages to conjure up, there were no Chestnut Grenades used during the first world war.

In fact, according to Chemistry in Britain (February 1987), the Royal Society of Chemistry's monthly periodical (now superceded by the much trendier-named Chemistry world) and the Imperial War Museum in London, the horse chestnuts were a source of acetone, a solvent needed for the production of cordite, the exciting new 'smokeless powder' that changed firearms from battlefield smoke machines to the lean, mean widow-makers of 20th-century warfare.

65% guncotton, 30% nitroglycerine and 5% petroleum jelly, cordite had to be gelatinized before it could be packed into shells and small arms munitions, a process to which acetone was vital. However, when war broke out, there were only 3200 tons of acetone squirrelled away for military use. Previously, the only industrial method of producing acetone was the destructive distillation of wood, a market which the (rapidly decreasing) lush forests of North America pretty much had cornered. It was clear, however, that not enough acetone could be imported from the United States to meet Britain's wartime needs.

So the minister of munitions, David Lloyd George, appointed Chaim Weizmann, a chemist who had emigrated from mainland Europe in 1904, to solve the acetone problem. Weizmann had patented a process whereby acetone could be produced by fermentation of maize and potatoes, so the Poms started importing maize from the United States instead. The Germans, not being utter morons, launched a submarine offensive in the Pacific in 1916, and made intercontinental transport a serious problem. Stocks of maize, and of acetone, ran dangerously low.

So Weizmann, the enterprising and single-minded individual that he was, adapted his process so that horse chestnuts could be substituted, although they were far from ideal. A factory was built at King's Lynn in Norfolk specifically for processing chestnuts, and vast quantities of them were gathered by schoolchildren all over England. Of course, actually getting them to the factory was less straightforward - letters to The Times complained of huge bags of chestnuts sitting rotting at train stations.

Finally, in April 1918, the King's Lynn factory began making chestnut-derived acetone in earnest, enjoying a fruitful and pithy lifetime of 3 short months before being closed again in July 1918.

Our boy Lloyd George, however, was ever so grateful to Weizmann. When he was made Prime Minister he allowed Weizmann - a firm Zionist - free access to his foreign secretary, A. J. Balfour. Students of Palestinian history might recall the infamous Balfour Declaration, in which Mother England expressed complisance in "the establishment in Palestine of a national home for the Jewish people."

In fact, students of Palestinian history will probably have long ago recognised Chaim Weizmann as the first president of Israel, a position he held from 1948 until his death in 1952.

So remember, as Israel slowly conkers the Middle East: pretty and tempting they might be, but horse chestnuts really are a bitter, toxic fruit.