dose

Manganism has been known about since the 19th century, when miners exposed to ores containing manganese[…]began to totter, slur their speech and behave like someone inebriated. The poisoning was irreversible, and soon ended in psychosis and death. Nowadays workers are exposed to far lower doses and manganism is rare.

I had then, as you remember, just returned to London after a lot of Indian Ocean, Pacific, China Seas - a regular dose of the East - six years or so, and I was loafing about, hindering you fellows in your work and invading your homes, just as though I had got a heavenly mission to civilise you.

It would be very expensive to cure a dose here, as well as unbelievably painful.