 In his early years, Matignon studied heat of combustion for major gaseous hydrocarbons and standard enthalpy of formation for ethanol, formic acid, acetic acid and various sugars.He extended this work to a family of 70 urea derivatives and formulated several thermochemical rules, for example, that the replacement of hydrogen attached to nitrogen by an alkyl radical increases the heat of combustion more than when the replacement is carried out at a carbon atom.This led to such practical conclusions as nitric esters are more powerful explosives than nitro-derivatives.