The nineteenth century was a period of unprecedented economic development during which the emerging modern science of chemistry as applied to agriculture contributed to the ability to feed the growing populations of industrial nations. This was based on an understanding of the role of fertilizers—containing nitrogenFertilizersnitrogen, phosphorusFertilizersphosphorus, and potassium—as essentialFertilizerspotassium elements of life, and their availability from natural sources. In the case of the most important fertilizers, those containing nitrogenFertilizersnitrogen, concerns that the main natural source, the nitratesNitrates (sodium nitrate) imported to Europe and the US from South America, would be spent by the early twentieth century presented chemists with a great challenge: the fixing, with the aid of electricity, of the unreactive nitrogen from the atmosphere. This followed developments in academic and private laboratories and in certain seemingly unrelated sectors of the chemical industry.