who came up with the law of conservation of mass
Conservation of mass The concept of mass conservation is widely used in many fields such as chemistry, mechanics, and fluid dynamics. Historically, mass conservation was discovered in chemical reactions by Antoine Lavoisier in the late 18th century, and was of crucial importance in the progress from alchemy to the modern natural science of chemistry.
First law of thermodynamics The first law of thermodynamics was developed empirically over about half a century. The first full statements of the law came in 1850 from Rudolf Clausius and from William Rankine; Rankine's statement is considered less distinct relative to Clausius'.[2] A main aspect of the struggle was to deal with the previously proposed caloric theory of heat.