Humans, as hopelessly insatiable consumers, have relied on horses to create antivenom and chicken eggs to make vaccines. But scientific progress in recent decades means we’re almost at the point where we can chemically synthesize the molecules we need to make life-saving products—without having to ruffle any feathers. Niko McCarty and Xander Balwit offer a fascinating, accessible survey of the history of our chemical needs and the science behind chemical synthesis.
In ancient times, the Phoenicians – and the Greeks and Romans after them – made Tyrian purple dye in the world’s first chemical industry. They began by carefully extracting hypobranchial glands (which produce various compounds, including colorful pigments) from the inner roof of the snails’ shells and letting them ferment in an airtight container. From here, they would either purify the mixture and dry it for use as a pigment or employ the fermented glands directly on fabric. In this latter process, it was crucial to monitor the pH, otherwise the cloth would be at risk of felting, or clumping together, in overly alkaline solutions. Careful management of exposure to sun and air was similarly essential, so that the mixture could oxidize enough to develop the desired purple shade, but not so much that it turned blue.
At the height of production, so many snails were killed to make dye that a heap of discarded shells in the ancient city of Sidon was said to have ‘created a mountain 40 meters high’. But when Constantinople fell to the Ottoman Empire in 1453, the knowledge required to make Tyrian purple vanished for the next 550 years.
Two popular theories explain how the knowledge was lost. The first suggests that when the Byzantine Empire fell, the Catholic Church – whose cardinals wore garments dyed with Tyrian purple – lost access to its large dye factories and were forced to transition to cheaper red garments, thus diminishing demand for the dye.
