How did kieselguhr help turn nitroglycerin into dynamite?

Kieselguhr—a porous, siliceous diatomaceous earth—was instrumental in transforming nitroglycerin into dynamite by acting as an absorbent.

Because liquid nitroglycerin was notoriously dangerous to handle and difficult to use, Alfred Nobel discovered that this porous material could soak up large quantities of the explosive. This process resulted in a stable, solid product that was significantly safer to handle and easier to transport than nitroglycerin alone. Nobel’s original mixture, which he called Dynamite No. 1, consisted of 75 percent nitroglycerin and 25 percent kieselguhr.1

While kieselguhr provided the necessary physical stabilization, Nobel later realized it was an inert substance that detracted from the explosive's power by absorbing heat. Consequently, he eventually replaced it with active ingredients, such as wood pulp and sodium nitrate, to further improve the efficiency and strength of his dynamite formulations.1