That first article says, "...the carbonic acid and nitrogenous compounds generated in diminutive quantities in the electric arc produce no sensible deleterious effects upon plants [inclosed] in the same space."
I'm trying to figure out what sort of light that was. Couldn't be incandescent, could it?
The article is from 1880, the same year Edison did his incandescent light bulb thing. His light bulb was a bulb, enclosed in a vacuum, not something that would emit 'carbonic acid and nitrogenous compounds' into its environment.
The article mentions an electric arc. Edison's bulb was not an arc, it was a carbon filament.
An exposed electric arc is super dangerous and takes a lot of energy to keep going.
Were those old people growing with incandescent light? Article says artificial and natural light gave about the same results.