Get the density of the material. Numerous free online sources are available for this information. For example, the densities of aluminum, salt and iron are about 2.7, 2.16 and 7.8 grams per milliliter, respectively.
Convert the mass in grams to volume in milliliters. Volume equals mass divided by density. For example, if the material is made of pure iron, then 159.6 grams equal about 20.46 milliliters (159.6 grams divided by 7.8 grams per milliliter).
Convert milliliters to liters. One liter equals 1,000 milliliter, which means one milliliter equals 0.001 liter. Therefore, 159.6 grams equal 20.46 milliliters or 0.02046 liter. (See Reference 1)