Source: Found while doing research relating to the death by gas of Private Michael Welsh, 53173. News clipping attached refers to a soldier that led to the discovery of this soldier. Though listed in the Nominal Roll, he was missed.
Family Search: When Joseph Mason was born on 26 April 1883, in Eston, Yorkshire, England, United Kingdom, his father, John Mason, was 32 and his mother, Catherine Sarah Mason, was 28. He married Ethel Marie Hogg on 4 January 1919. They were the parents of at least 1 daughter. He immigrated to Canada in 1913 and lived in St. Thomas, Elgin, Ontario, Canada in 1921. He registered for military service in 1914. In 1914, at the age of 31, his occupation is listed as railway employee. He died on 7 July 1959, in St. Thomas, Ontario, Canada, at the age of 76, and was buried in Elmdale Memorial Park Cemetery, St. Thomas, Elgin, Ontario, Canada.
History of the 18th Battalion CEF, "The Fighting Eighteenth" 