Fire analysis in the eighteenth century: Herman Boerhaave and scepticism about the elements.

In the eighteenth century, many chemists asserted that chemical operations could not decompose a substance into its natural, constituent elements or principles. One such chemist was Herman Boerhaave (1668-1738), who claimed, following the work of Robert Boyle and Joan Baptista van Helmont, that examples of these alleged analyses were, in fact, not reductions of a body into elements, but rather the rearrangement of its particles by the fire. Since we cannot observe the shape and arrangement of particles directly, he reasoned, any claim regarding the elemental status of a substance was purely speculative and inadmissible in his chemistry. As a result, Boerhaave devised a system of chemistry which, in effect, accepted no elemental substances and which focused on understanding how the chemist's 'instruments,' including fire and chemical menstrua, effected changes in matter. I conclude by showing how Boerhaave's conclusion had ramifications for later developments in chemistry, especially those of the French Stahlians and of Antione Lavoisier.

Measuring Fire: Herman Boerhaave and the Introduction of Thermometry into Chemistry.

This essay examines Herman Boerhaave's work with the instrument maker, Daniel Gabriel Fahrenheit, on integrating the thermometer into the practice of eighteenth-century chemistry. Boerhaave utilized the thermometer to generate empirical evidence for the existence and actions of his instrument, "fire," by incorporating the instrument into pedagogical demonstrations, chemical research on heat, and, finally, the performing of operations. I examine how the use of the thermometer altered the chemists' traditional approach to heat, based on skilled sense perception and experiential judgment, and suggest that the threat to traditional practice posed by the instrument explains some of the resistance to it among some chemists in the mid-eighteenth century.