One of Edison's Lesser Known Inventions

 By Bruce Shawkey

Everyone remembers Thomas Edison for his invention of the light bulb. But in fact, Edison held patents for some 1,093 patents. One oof those was for a type of cement. Here is the story.

Edison invested in and developed a type of Portland cement, which he manufactured through his Edison Portland Cement Company. He improved the manufacturing process and explored many unusual applications for concrete made from his product, including entire houses and furniture. 

The origins of Edison's cement business

Edison entered the cement business after his attempt to mine low-grade iron ore proved unprofitable. His ore-crushing process produced large amounts of fine waste sand, which he discovered was an excellent aggregate for cement. He adapted his ore-milling machinery and, in 1899, founded the Edison Portland Cement Company in New Village, New Jersey. 

Innovations in manufacturing

Edison made several key improvements to cement manufacturing, most notably inventing the long rotary kiln. At 150 feet, his kilns were significantly longer than the 60- to 80-foot industry standard at the time and were more efficient. He licensed this technology to other manufacturers, helping to drive down costs across the industry and leading to a cement surplus. 

Unique applications for concrete

To generate new demand for his product, Edison promoted some ambitious and unconventional uses for concrete. 

Mass-produced concrete houses: In the early 1900s, Edison began experimenting with casting entire concrete homes in a single, continuous pour. His goal was to create affordable, durable, and fireproof housing for working-class families. While the process was technically sound—some of his concrete houses are still standing in New Jersey—the cost of the large, 2,300-piece cast-iron molds proved too expensive for widespread adoption.

Concrete furniture: He also patented and attempted to market concrete furniture, including bedroom sets and phonograph cabinets. This venture failed, as the furniture was impractical and unpopular with consumers. 

Legacy of the company

Despite the failures of some of his more unusual ideas, Edison's cement company played an important role in infrastructure development. 

Yankee Stadium: The Edison Portland Cement Company's most famous achievement was providing all the concrete for the construction of the original Yankee Stadium in 1922. The concrete was so durable that when the stadium was renovated in the 1970s, the original concrete walls were left in place.

Business failure: The company struggled financially for most of its existence and ultimately went bankrupt during the Great Depression, shortly after Edison's death in 1931. 

Edison had a net worth of $12 million at the time of his death on October 31st, 1931. The modern, inflation-adjusted equivalent of his net worth is $170 million. However, it should be noted that at various points in his life, Thomas Edison experienced extreme financial hardship. He was nearly bankrupt on a number of occasions during periods where his expenditures on inventions vastly outpaced the income from previous inventions. At one point, automotive tycoon Henry Ford was forced to write off a $750,000 debt owed by Edison.