Where are all the Oxalic Acid Poison Mysteries?

I was drawn to ask this very question when I was recently perusing Barzun and Taylor’s A Catalogue of Crime, in particular their review of Murder of a Chemist (1936) by Miles Burton. In this review is the following statement: ‘The poison is the oxalic acid so popular in the thirties.’ And my first response was: “Really?” Popularity often involves a large number of something, be it sales of an ice cream brand or the number of people who watched a given film during opening week. So, when Barzun and Taylor expressed their opinion, I would argue they were implying there were a lot of mysteries written in the 1930s which involved oxalic acid poisoning. Yet I could not think of that many, only two. Therefore, I naturally decided to do a bit of research and see if I could find this plethora of fictional poisonings. And this post is the result of that research.