Visual Evidence

An unusual relic offers a fuller picture of a chemist’s life and work.

By Andrew Mangravite | April 28, 2016
Walter Snelling Photograhpic Experiment

One of chemist Walter Snelling’s many photographic experiments.

Science History Institute

Walter O. Snelling, the man generally credited as the “father of propane,” could be described more accurately as a leading expert in the field of military ordnance. Snelling’s papers contain exhaustive files on explosives of all types, covering every aspect of their manufacture and use. But certain archival collections by their size and complexity cease to function as single-topic sources and instead become encyclopedic reference collections. The Papers of Walter O. Snelling make up such a collection, one that offers a grand overview of the state of industrial chemistry in the United States from the 1920s through the mid-1950s.

Snelling was director of research for the Trojan Powder Company from 1917 until his retirement in 1954. From this position very little in the area of industrial chemistry, from manufacture of air-conditioning units to the processing of frozen orange-juice concentrate, escaped his notice—and he kept files on all of it!

Snelling was also a freelance inventor, the holder of 179 patents, and a man of fiercely held opinions. He had been a “star” at the U.S. Bureau of Mines for his development of underwater explosives that greatly eased construction of the Panama Canal. He also had been made wealthy from a high-pressure, high-temperature oil-cracking process and other innovations he developed and later sold to Standard Oil and the company now named Texaco. But success and wealth couldn’t calm a man his son Charles later labeled a “bully.” When Snelling believed a snack-food manufacturer was violating one of his patents on the degreasing of fried potato chips, several feet of legal documents now in our archives were the result. Convinced that a rival explosives manufacturer was contravening U.S. neutrality laws by selling explosives to warring powers, he pursued the company for years. Perhaps much of this bulldog tendency resulted from a belief that the U.S. Patent Office and his superiors at the Bureau of Mines had tried to rob him of credit for his oil-cracking process, instead favoring the claims of his bureau colleague W. F. Rittman.

Propane, what Snelling is best known for today, was another source of discontent. Although he devised the method to capture and liquefy the gas, his company never saw a profit. Ultimately, he sold his patent rights to Frank Phillips in 1914. “My father later complained to Frank, ‘You’re making a billion dollars on my invention and you paid me $50,000. You should have paid me much more,’ ” Charles Snelling recounted to a propane industry magazine in 2012. “Frank said, ‘Doc, I shouldn’t have paid you anything. I didn’t make any money on this until after the patents expired.’ ”

This defeat perhaps led Snelling back to pyrotechnics and military ordnance, the field in which he had scored his first great success and in which he later scored a rather odd photographic achievement. During World War II, Snelling was Trojan’s representative at the Plum Brook Ordnance Works in Sandusky, Ohio. There, a routine investigation into the effects of exposing TNT to sunlight late in 1942 led to a startling discovery—that TNT could be used in photography! More precisely, TNT could be used as a substitute for silver salts in coating photographic paper.

Snelling made detailed observations of TNT’s photosensitive properties and experimented by photographing Major Lewis K. Kallmyer, commanding officer of the works, using his TNT-treated paper to develop the image. The result looks very much like a sepia-toned print. Although Snelling was usually quick to secure patents for his various discoveries, he seemed to regard this work as a mere sideshow to his more immediate wartime concerns.

For all you amateur photographers, here is Snelling’s formula, as recounted in a 1956 letter to a colleague:

Start with a solution of 10 parts of TNT, 10 parts resorcinol, and 80 parts acetone. Dip filter paper into this solution, allow the acetone to evaporate in a dark room, and when dry the paper is ready for exposure.