—Mr. John Boyns, of Penzance, schoolmaster, had a narrow escape from poison last week.   He had been accustomed to take a small quantity of laudanum for spasms in the stomach, and sent to a chemist for his accustomed dose.  From some mistake, either on his part or on that of the dispenser, pure instead of diluted laudanum was sent him, and he swallowed 500 instead of 15 drops.   He  felt  a pain in the throat and started for his doctor's residence immediately. An emetic was given and smart exercise taken,  We believe Mr. Boyns has since entirely recovered from his unpleasant predicament.