Iron comes from Iron Ore via the Forge. Iron Ore can be found in Iron Nodes in the Stalactite layer and Lava layer. The ore has to be harvested with an Extractor, as the node itself cannot be pulled with Power Cells, it also cannot be placed. All Ores can be smelted into bars in a Forge for further processing.
It depends on the substance (water for example has 1000 grams to a liter, other substances have more grams or less grams to a liter depending on a property (called the density measured in grams / liter) of the substance.
Quick Answer. One liter is equal to 1,000 milliliters. In the metric system, the prefix milli- is used before basic units, such as liter, gram and meter, to indicate that the measurement is one-thousandth of that basic unit. Continue Reading.