Scientists often talk informally of 鈥渂eauty鈥 in ideas, experiments and theories - but what do they mean by it? My recent book with Chinese science photographers Yan Liang and Wenting Zhu offered one answer. Titled 鈥淭he Beauty of Chemistry鈥, it presented astonishing photos of chemical processes, many based on the videos Yan and Wenting have made for their 鈥淓nvisioning Chemistry鈥 project, which has received international acclaim. I argue that chemistry excels in its sensual allure: its colours, textures, patterns, even smells, speak immediately to the senses and are often what draw chemists to study their subject. All the same, I argue, scientific notions of beauty are complicated and not always compatible with the way the word is used in art and aesthetics.