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.
You may have seen my post from last year of my backyard progress, if you did then you understand why I dislike ivy so much. Itâs for this reason that I loved this tip from Barbara for how to kill poison ivy! * Combine 1 gallon white vinegar with 1 cup salt and 2 TBSP blue dawn dish soap.