At the turn of the 19th to the 20th century, it became possible to break down air into its components and explore commercial applications. A range of previously unimaginable uses emerged. There is oxygen, which, in combination with acetylene, revolutionized metal processing, and nitrogen, which enabled the Haber-Bosch process for ammonia production and later also shock freezing and the manufacturing of electronic components. Today, the products of this invisible industry find applications in all sectors of manufacturing and beyond. This fascinating technical and commercial development is described for the first time in this book. The authors not only illustrate the history of an entire industry but also show that the most stable structures are those that derive their strength from air.