Hydraulic fracturing, or “fracking,” is a technique used to break up rock deep underground in order to release the natural gas trapped inside it. The fluid injected into the rock is generally water-based, but the specific mixtures of chemicals dissolved in that water are generally a closely guarded secret. Using fluids to crack rocks is an old technique dating back over a hundred years, but modern techniques trace back to experiments in the 1940s by Floyd Farris and J.B. Clark, who worked for Stanolind Oil and Gas.