Originally, exactly as much as a volume of water equal to the cube of the hundredth part of the metre, at the temperature of melting ice. I don't find that terribly helpful. Not many did. That's why, in 1889, the mass of the kilogram was redefined as being equal to the IPK.
Boiling water is also an effective poison ivy killer. If the area where you will be killing poison ivy has no other plants you wish to keep, pour boiling water over the poison ivy plant. Boiling water will kill any part of a plant that it comes in contact with, so be careful using this around desirable plants.
17 Home Remedies for Poison Ivy. Contact with poison ivy, poison oak, or poison sumac often goes hand-in-hand with camping and other outdoor activities. Outdoor enthusiasts by the tentful have had to cut trips short after an unfortunate encounter with one of this threesome. The problem stems from the plant's colorless oil called urushiol.