Tracts / written by Robert Boyle ; containing New experiments, touching the relation betwixt flame and air, and about explosions ; An hydrostatical discourse occasion'd by some objections of Dr. Henry More against some explications of new experiments made by the author of these tracts ; to which is annex't an hydrostatical letter, dilucidating an experiment about a way of weighing water in water ; New experiments of the positive or relative levity of bodies under water, of the air's spring on bodies under water, about the differing pressure of heavy solids and fluids.