what does blister mean from the following context
The whole text can be found here.A wood-fire is not a permanent thing. I got up every twenty minutes and renewed ours, and this gave Mrs. McWilliams the opportunity to shorten the times of giving the medicines by ten minutes, which was a great satisfaction to her. Now and then, between times, I reorganized the flax-seed poultices, and applied sinapisms and other sorts of blisters where unoccupied places could be found upon the child. Well, toward morning the wood gave out and my wife wanted me to go down cellar and get some more.
I think blaster would make more sense.
It makes sense now.