Air Products & Chemicals (NYSE:APD) is a supplier of hydrogen and helium and has built positions in growth markets such as semiconductor materials, refinery hydrogen, natural gas liquefaction, home healthcare and advanced coatings and adhesives.
Book: “Out of Thin Air: A History of Air Products and Chemicals, Inc., 1940-1990,” by Andrew J. Butrica, Praeger, NY, 1990. See the review posted on Motley Fool's Books--Non-fiction discussion board: 
Air Products is best known for its air separation technology producing nitrogen and oxygen and recovering trace components such as argon. Traditionally the company contracts with major customers to build large plants often on site to supply their requirement and then serves other customers out of that site.
In 2015, Air Products announced plans to spin off its specialty chemicals businesses under the name Versum Materials. The new company will have six divisions and sales of about $2B. The spinoff should be completed by September, 2016. This will leave Air Products as a pure play in the industrial gases business.