18. The stagnating air of the hold of a ship.
19. Bilge water.
20. Water that had long been confined in hogsheads at sea.
21. Stagnating rain water.
22. The stagnating air of close cellars.
23. The matters which usually stagnate in the gutters, common sewers, docks, and alleys of cities, and in the sinks of kitchens. A citizen of Philadelphia, who had a sink in his kitchen, lost a number of cats and dogs by convulsions. At length one of his servants was affected with the same disease. This led him to investigate the cause of it. He soon traced it to his sink. By altering its construction, so as to prevent the escape of noxious air from it, he destroyed its unwholesome quality, so that all his domestics lived in good health in his kitchen-afterwards.
24. Air emitted by agitating foul and stagnating water. Dr. Franklin was once infected with an intermitting fever from this cause.
25. A duck pond. The children of a family in this city were observed, for several successive years, to be affected with a bilious remitting fever. The physician of the family, Dr. Phineas Bond, observing no other persons to be affected with the same fever in the neighbourhood, suspected that it arose from some local cause. He examined the yard belonging to the house, where he found an offensive duck pond. The pond was filled with earth, and the family were afterwards free from an annual bilious fever.