Energy content of biofuel (J/kg) or equivalent units. Energy density is the amount of energy stored in a fuel per unit volume, expressed in SI units as joule per litre (J/L) or equivalent units. The table below includes entries for popular substances already used for their energy, or being discussed for such use. The second column shows specific energy, the energy content in megajoules per unit of mass in kilograms, useful in understanding the energy that can be extracted from the fuel. The third column in the table lists energy density, the energy content per liter of volume, which is useful for understanding the
Socialism: Utopian and Scientific Socialism: Utopian and Scientific Socialism: Utopian and Scientific is a short book first published in 1880 by German-born socialist Friedrich Engels. The work was primarily extracted from a longer polemic work published in 1876, "Anti-Dühring." It first appeared in the French language. The title "Socialism: Utopian and Scientific" was adopted for the first English edition in — the tenth language in which the book appeared. Intended as a popularization of Marxist ideas for a working class readership, the book was one of the fundamental publications of the international socialist movement during the late 19th and early 20th centuries, selling tens