 This industry was so lucrative that it led to overpopulation in the Western Isles of Scotland, and one estimate is that 100,000 people were occupied with "kelping" during the summer months.In the same period, soda ash ("la soude de Narbonne") was produced in quantity from glasswort proper around Narbonne, France.The commercialization of the Leblanc process for synthesizing sodium carbonate (from salt, limestone, and sulfuric acid) brought an end to the era of farming for soda ash in the first half of the 19th century.