] I can vouch for the continued usage of "phlogiston" even today: my French-Canadian in-laws, in northern Quebec, refer to rubbing creams like Ben-Gay as "anti-phlogistine" .

Thanks for putting me onto the right track. I've just done a google search, and found a couple of hundred references for `antiphlogistine'

It's a hot poultice, or, as your in-laws say, a rubbing cream. It's a trademarked brand - indeed, there's even been a law case about it (see link below).

It seems to be especially popular among French speakers, if the proportion of web pages is anything to go by. Ironic, in view of the Priestley-Lavoisier thing.