<P> Practical attempts to improve the refining of ores and their extraction to smelt metals were an important source of information for early chemists in the 16th century, among them Georg Agricola (1494--1555), who published his great work De re metallica in 1556 . His work describes the highly developed and complex processes of mining metal ores, metal extraction and metallurgy of the time . His approach removed the mysticism associated with the subject, creating the practical base upon which others could build . </P> <P> English chemist Robert Boyle (1627--1691) is considered to have refined the modern scientific method for alchemy and to have separated chemistry further from alchemy . Although his research clearly has its roots in the alchemical tradition, Boyle is largely regarded today as the first modern chemist, and therefore one of the founders of modern chemistry, and one of the pioneers of modern experimental scientific method . Although Boyle was not the original discover, he is best known for Boyle's law, which he presented in 1662: the law describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system . </P> <P> Boyle is also credited for his landmark publication The Sceptical Chymist in 1661, which is seen as a cornerstone book in the field of chemistry . In the work, Boyle presents his hypothesis that every phenomenon was the result of collisions of particles in motion . Boyle appealed to chemists to experiment and asserted that experiments denied the limiting of chemical elements to only the classic four: earth, fire, air, and water . He also pleaded that chemistry should cease to be subservient to medicine or to alchemy, and rise to the status of a science . Importantly, he advocated a rigorous approach to scientific experiment: he believed all theories must be tested experimentally before being regarded as true . The work contains some of the earliest modern ideas of atoms, molecules, and chemical reaction, and marks the beginning of the history of modern chemistry . </P> <Dl> <Dt> Optics </Dt> </Dl>

What sources of knowledge were most central to the scientific revolution